DE69309194T2 - Unit of work, method of assembling this unit and image forming apparatus - Google Patents

Description

The present invention relates to: an electrophotographic process cartridge; a combination of such a cartridge and an image forming apparatus such as a laser beam printer, an LED printer, an electrophotographic copying machine, a facsimile machine, a word processor; and a method for producing process cartridges.

For many years, imaging devices have been available that contain replaceable process cartridges containing developer (or toner) and other devices that require periodic replacement. When the developer runs out or when one of the other devices fails to work properly, the user can easily replace the cartridge with a new one. In this way, maintenance of the device is made easy.

The present invention relates in more detail to a process cartridge comprising a housing containing a container for a developer, a rotatable photosensitive drum, a driven gear coaxial with the drum and loading, developing and cleaning devices cooperating with the drum, the housing having a first opening for the passage of light to the drum to produce a latent image thereon and a second opening for transferring developed images from the drum to a transfer material, said cartridge being adapted to be removably inserted in a direction transverse to the axis of the drum into an image forming apparatus having an arrangement for guiding the cartridge to an operative position in the apparatus and for storing the cartridge in this operative position in which said driven gear is provided with a drive gear of the device, said drum being mounted in said housing at its front portion with respect to the direction of insertion, outwardly projecting guide means being arranged on said housing on opposite sides of said front portion to cooperate with said arrangement which causes the cartridge to be guided, and a rear portion of said housing with respect to the direction of insertion being designed to be gripped by an operator to insert and remove the cartridge from the device. US-A-5 115 272 and patent application JP-A-04-70767 disclose such a cartridge.

Although not described in JP-A-04-70767, the casing of a process cartridge may be formed of a plurality of casing members or frames which are bonded together. For reasons of strength, a relatively expensive material such as polyphenylene ether or polyphenylene oxide may be selected for one of the casing members which supports, for example, the photosensitive drum, but for reasons of cost, a relatively low-strength material such as polystyrene resin may be selected for another of the casing members which contains, for example, the developer material.

A preferred method of joining at least two of the housing parts together will use ultrasonic welding. However, welding of polyphenylene ether or oxide and polystyrene resin is not particularly reliable.

More recently, the need to recycle used process cartridges has been recognized. If the housing parts cannot be immediately reused, they are crushed and remolded. However, if two housing parts made of polyphylene ether or oxide and polystyrene resin are welded together, they must either be separated before being remolded separately, or the The re-molded object may be a mixture of two different materials.

The case of the process cartridge of the present invention comprises front, middle and rear cases, wherein the rear case forms the developing container, the middle case forms a support for the developing device, and the front case forms a support for the photosensitive drum and includes a container for excess toner removed from the photosensitive drum; the front, middle and rear cases are formed of the same resin material; and the excess toner container includes internal ribs to reinforce the front case.

In this way, an inexpensive, low-strength material (such as polystyrene resin) can be used for the housing parts, and yet the reinforcing ribs of the front housing part can not only provide sufficient mechanical strength to enable the front housing part to properly support the photosensitive drum, but also to restrict the unintentional movement of the toner in the used or waste toner container to reduce the risk of leakage.

In the case where the rear and middle housing parts are welded together, the use of the same material composition for these two housing parts enables a reliable welding to be achieved. Furthermore, there is no need to separate these two housing parts when they are to be crushed and re-formed.

Specific embodiments of this invention will now be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a sectional side view of an image forming apparatus in which a process cartridge is mounted;

Fig. 2 is a perspective view of the image forming apparatus;

Fig. 3 is a longitudinal section of the process cartridge;

Fig. 4 is a perspective view of the process cartridge;

Fig. 5 is a partial view showing a left guide member;

Fig. 6 is a partial view showing a right guide member;

Fig. 7 is an exploded view of the process cartridge showing its housing parts;

Fig. 8A is a longitudinal sectional view of a photosensitive drum and Fig. 8B is a cross sectional view of the photosensitive drum ;

Fig. 9 is a perspective view of a conductive member contacting a metal shaft;

Fig. 10 is a diagram showing a loading roller and bearings therefor;

Fig. 11 is an exploded perspective view showing an overlapping relationship between a coating plate and toner leakage preventing seals;

Fig. 12 is a diagram showing a positional relationship between a developing blade and the toner leakage preventing seals and the coating plate;

Fig. 13A is a sectional view taken along the line A - A in Fig. 11 and Fig. 13B is a sectional view taken along the line B - B in Fig. 11;

Figs. 14A and 14B are views showing a case where a mold plate is bent;

Fig. 15 is an enlarged sectional view showing a state where a sharp rib is inserted into a developing blade;

Fig. 16 is a sectional view showing a state where an adhesive for an antenna wire has buckled;

Fig. 17A is a diagram showing a state where the adhesive is bulged by inserting the antenna wire, Fig. 17B is a diagram showing a state where the bulged adhesive is uniformed, and Fig. 17C is a diagram showing a state where a gasket is attached;

Fig. 18A is a diagram showing an unbent antenna wire, and Fig. 18B is a diagram showing the antenna wire which is bent;

Fig. 19 is a perspective view of a cartridge showing a state where a cover sheet is pulled obliquely;

Fig. 20 is a diagram showing a relationship between the cover sheet and the toner leakage preventing seal when the cover sheet is pulled obliquely;

Fig. 21 is a perspective view showing a state where a tear-preventing film is attached to the toner leakage preventing seal in spaced relation to an edge of the toner leakage preventing seal;

Fig. 22 is a diagram showing various dimensions of a photosensitive drum, a developing sleeve and a charging roller;

Fig. 23 is a diagram showing various dimensions of the charging roller;

Fig. 24 is a plan view showing toner passage preventing seals and shielding members arranged at both ends of a cleaning blade;

Fig. 25 is a perspective view showing the toner leakage preventing seal and the shielding members arranged at the end of the cleaning blade;

Fig. 26 is an explanatory view to illustrate a method of attaching the toner leakage preventing seal to the end of the cleaning blade;

Fig. 27 is a diagram showing a method of molding a developer housing part;

Fig. 28 is a diagram showing a method of molding a cleaning housing part;

Fig. 29 is a diagram showing a process for joining a toner housing part and a developer housing part by ultrasonic welding;

Fig. 30 is a diagram showing positioning pins and fitting holes formed on the toner housing part and the developer housing part in the width direction thereof;

Fig. 31 is a perspective view showing a plurality of fitting holes formed on the toner housing part in a longitudinal direction thereof and corresponding to positioning pins on the developer housing part;

Fig. 32A is a diagram showing a state where a toner-developer housing set rests on a mounting plate, while Fig. 32B is a diagram showing a state where the cleaning housing part rests on a mounting plate;

Fig. 33 is a diagram showing assembling steps by which the toner-developer housing set is assembled by an automatic machine;

Fig. 34 is a diagram showing assembly steps by which the cleaning housing part is assembled by means of an automatic machine;

Figs. 35 and 36 are views showing a construction or arrangement whereby the photosensitive drum does not come into contact with a table when the cleaning case member rests on the table;

Fig. 37 is a diagram showing a construction whereby a developing sleeve does not come into contact with a table when the toner-developer housing assembly rests on a table;

Fig. 38 is a partial exploded perspective view showing a method of connecting the toner-developer housing assembly and the cleaning housing part by connecting members;

Fig. 39A is a perspective view showing a state wherein the connecting members are attached while the

Fig. 39B is a sectional view showing a state where the links are connected;

Fig. 40 is a partial perspective view showing a left end face of a process cartridge;

Fig. 41 is a sectional side view showing a state in which the process cartridge is mounted on the image forming apparatus;

Figs. 42 to 45 are enlarged partial sectional views showing a state in which the process cartridge is mounted on the image forming apparatus;

Fig. 46 is an enlarged partial sectional view showing a state where the process cartridge is dismounted from the image forming apparatus;

Fig. 47 is a perspective view showing a mechanism for opening and closing a laser shutter;

Fig. 48 is a diagram showing a grippable part on which transverse ribs are formed;

Fig. 49 is a perspective view showing a state in which the grippable part of the process cartridge is gripped by hand;

Fig. 50 is a perspective view showing a grippable member in which a recess is formed;

Fig. 51 is a perspective view showing a grippable part on which a projection is formed;

Fig. 52 is a partial perspective view showing the arrangement of various contacts provided on a process cartridge;

Fig. 53 is a plan view showing the arrangement of various contacts provided on an image forming apparatus;

Fig. 54 is a sectional view showing a relationship between the contacts and the contact pins;

Fig. 55 is a detection circuit for detecting a remaining toner amount;

Fig. 56 is a diagram showing a relationship between a toner amount and a toner remaining amount detection voltage;

Fig. 57 is a circuit according to an embodiment wherein cartridge mounting is detected by an inverter;

Fig. 58 is a circuit according to an embodiment, wherein cartridge mounting is detected by a digital signal ;

Fig. 59 is a functional block diagram of a controller ;

Fig. 60 is an exploded perspective view of a cleaning housing part showing the internal structure thereof;

Figs. 61 and 62 are diagrams showing a bearing for a charging roller according to another embodiment;

Fig. 63 is a perspective view of a bearing for a loading roller according to another embodiment;

Fig. 64 is a diagram showing a mechanism according to another embodiment for preventing the deformation of a contact member;

Fig. 65 is a diagram showing a mechanism for preventing deformation of a contact element according to another embodiment;

Fig. 66 is an illustration of an embodiment wherein a second rib is sharpened on a developer housing part;

Fig. 67A is an explanatory diagram showing a state where an antenna wire is bent into a semicircular shape, while Fig. 67B is an explanatory diagram showing a state where the antenna wire is bent into a trapezoidal shape;

Fig. 68 is a diagram showing an embodiment in which a cutout is formed in a developer housing part and displacement of an antenna wire is prevented by inserting the antenna wire into the cutout;

Fig. 69 is a diagram showing an embodiment in which a round hole is formed in a developer housing part and displacement of an antenna wire is prevented by inserting the antenna wire into the round hole.

First, a process cartridge and an image forming apparatus using such a process cartridge according to a first embodiment will be described with reference to the accompanying drawings.

tions. [General description of a process cartridge and an image forming device on which this process cartridge is mounted] :

The overall construction of an image forming apparatus will be described first. Fig. 1 is a sectional view of a laser beam printer in which a process cartridge according to an aspect of this invention is mounted, Fig. 2 is a perspective view of the laser beam printer, Fig. 3 is a sectional view of the process cartridge, while Fig. 4 is a perspective view of the process cartridge.

As shown in Fig. 1, the image forming apparatus A is constructed so that a latent image is formed on a photosensitive drum (which is an example of an image bearing member) by causing imaging light from an optical system 1 to be irradiated onto the drum in response to image information, and the latent image is developed by a developer (hereinafter referred to as "toner") to form a toner image. In synchronization with the formation of the toner image, a recording medium 2 is conveyed to an image forming station of a process cartridge B by a conveying device 3, and in the image forming station, the toner image formed on the photosensitive drum is transferred to the recording medium 2 by means of a transfer device 4. Then, the recording medium is transferred to a Fixing device 5, where the transferred toner image is fixed to the recording medium 2. The recording medium is then conveyed to a discharge station 6.

As shown in Fig. 3, in the process cartridge B which is the image forming station, the rotating photosensitive drum (which is an example of an image bearing member) 7 is uniformly charged by a charger 8. The latent image is formed on the photosensitive drum 7 by irradiating the imaging light from the optical system 1 through an exposure region 9, and then the latent image is developed by a developing device 10 to make the image visible as a toner image. The toner image is then transferred to the recording medium 2. On the other hand, after the transfer operation, the residual toner remaining on the photosensitive drum 7 is removed by a cleaning device 11.

It is to be noted that the process cartridge B comprises a toner housing part 12 as a first housing part containing a toner container, a developer housing part 13 as a second housing part containing a developing cylinder, and a cleaning housing part 14 as a third housing part containing the photosensitive drum 7 and the cleaning device 11, etc. In Fig. 2, reference numeral isa denotes an operation panel on which a setting key for the number of copies, a density setting key, a test copy key, a lamp for informing the exchange of the cartridge, which will be discussed later, and the like are provided.

Various components of the image forming apparatus A and the process cartridge B mounted thereon are explained in detail below.

[Image forming device] :

First, the various components of the image forming device A, ie the optical system, the conveyor, the transfer device, the fixing device and the cartridge holding device are described in this order.

(Optical system):

The optical system 1 serves to make the imaging light incident on the photosensitive drum 7 in accordance with the image information supplied from an external device, etc. As shown in Fig. 1, the optical system comprises an optical unit 1a in which a polygon mirror 1b, a scanning motor 1c, a focusing lens 1d, a deflection mirror 1e and a laser diode 1f are housed and which is arranged within a frame 15 of the apparatus A.

When an image signal is output from an external device such as a computer, a word processor, and the like (see the host 62 in Fig. 59), the laser diode if emits the light in response to the image signal, and the light is supplied to the polygon mirror 1b as imaging light. The polygon mirror 1b is rotated by the scanning motor ic at a high speed, and the imaging light reflected by the polygon mirror 1b is made incident on the photosensitive drum 7 via the focusing lens ld and the reflecting mirror le, thereby selectively exposing the surface of the photosensitive drum 7 to form a latent image corresponding to the image information on the photosensitive drum 7.

(Recording media conveyor):

The conveyor device 3 for transporting or conveying the recording medium (eg an OHP film, a thin film or the like) 2 is explained below. The conveyor device 3 according to the embodiment shown allows both manual sheet feeding and cassette sheet feeding. As shown in Fig. 1, in the manual sheet feeding, one or more recording media 2 are placed on a sheet supply tray 3a, whereupon the image forming operation is initiated. As a result, the recording medium 2 is fed from the sheet supply tray 3a into the image forming apparatus by the rotation of a peel roller 3b. Incidentally, the recording mediums, which are placed as a plurality of recording mediums 2 on the sheet supply tray 3a, are separated by a pair of separating rollers 3c1, 3c2, and the separated recording medium is transported until a leading edge of the recording medium abuts against a nip between a pair of aligning rollers 3d1, 3d2. The aligning roller pair 3d1, 3d2 is rotated in response to the image forming operation to feed the recording medium 2 to an image forming station. Further, after image formation, the recording medium 2 is conveyed to the fixing device, and then it is discharged to the discharge section 6 by a pair of intermediate discharge rollers 3e and a pair of discharge rollers 3f1, 3f2. Guide members 39 are arranged between the fixing device 5 and the intermediate discharge rollers and between the intermediate discharge rollers and the discharge roller pair to guide the recording medium 2.

The sheet supply tray 3a has an inner member 3a1 and an outer member 3a2. In an inoperative state, the inner member 3a1 is housed in the outer member 3a2, and the outer member 3a2 forms, as shown in Fig. 2, a part of the frame 15 of the device.

On the other hand, for the cassette sheet feed, as shown in Fig.1, a receiving part for a cassette 3h is provided in a lower portion within the frame 15. When the manual sheet feed is not effected, the recording media 2 in the cassette 3h mounted in the receiving part are fed one by one from the top to the alignment roller pair 3d1, 3d2 by the rotational movement of a peeling body 3i and a feed roller 3j. On a downstream side of the alignment roller pair 3d1, 3d2, the recording media in the same way as in the manual sheet feed. Incidentally, a sensor 3k serves to detect the presence/absence of the recording medium 2 in the cassette 3h.

(Transfer facility):

The transfer device 4 serves to transfer the toner image formed on the photosensitive drum 7 to the recording medium 2, and comprises, as shown in Fig. 1, a transfer roller 4. More specifically, the recording medium 2 is pressed against the photosensitive drum 7 of the process cartridge B mounted on a holder (described later) by the transfer roller 4, and by applying a voltage of the polarity opposite to that of the toner image formed on the photosensitive drum 7 to the transfer roller 4 (in the illustrated embodiment, by effecting the constant current control with a DC voltage of about 1000 V), the toner image on the photosensitive drum 7 is transferred to the recording medium 2.

(Fixing device)

The fixing device 5 serves to fix the toner image transferred to the recording medium 2 by applying the voltage to the transfer roller 4. As shown in Fig. 1, the fixing device comprises a rotating drive roller 5a and a rotating fixing roller 5b having a heating element 5c therein, which is pressed against the rotating drive roller 5a. More specifically, as the recording medium 2, onto which the toner image has been transferred in the image forming station, passes between the drive roller 5a and the fixing roller 5b, it is subjected to a pressure due to the counterpressure between the rollers 5a, 5b and a heat due to the heating of the fixing roller 5b, so that the transferred toner image is fixed to the recording medium 2.

(Cartridge holding device):

The cartridge holding device for mounting the process cartridge B is provided in the image forming apparatus A. After an openable/closable cover 16 is opened, the installation or removal of the process cartridge B is effected. In detail, the openable/closable cover 16 is pivotally mounted on an upper part of the frame via hinges 16a. On the other hand, as shown in Figs. 5 and 6, a left guide member 17 and a right guide member 18 are mounted on the inner side walls. The guide members 17, 18 have first guide pieces 17a and 18a inclined forward and downward, and second guide pieces 17b and 18b arranged above the first guide pieces. The guide pieces 17a, 17b and 18a, 18b are arranged in a left-right symmetry. Supporting parts 17c, 18c (which will be described later) for supporting drum bearings of the process cartridge B are formed at ends of the first guide pieces 17a, 18a, respectively, and intermediate step parts 17b1 and 18b1 are formed at the second guide pieces 17b, 18b, respectively.

Further, the left guide member 17 has a cartridge swing movement regulating guide 17d arranged above the second guide piece 17b. The right guide member 18 is provided with a shutter cam control part 18d for opening and closing a drum shutter 35 of the process cartridge B, and the cam control part 18d is arranged above the second guide member 18b.

In addition, pressure elements 19 are mounted above the pivoting movement regulating guide 17d and the shutter cam control part 18d, these pressure elements serving to press the mounted process cartridge B downward via torsion coil springs 19a. Furthermore, stop pieces 20 for positioning the process cartridge B are arranged on front sides (front sides in a cartridge insertion direction) of the left and right guide members 17, 18.

After the swing cover 16 is opened, the process cartridge B can be mounted inside the image forming apparatus while being guided by the first and second guide pieces 17a, 18a and 17b, 18b of the left and right guide members 17, 18. The mounting procedure for the process cartridge will be explained after the construction of the process cartridge is described.

[Process Cartridge]:

Various components of the process cartridge B, which is to be mounted in the image forming device A, are described below.

The process cartridge B contains an image-bearing component and at least one process functional element. The process functional element can be, for example, a charging device for charging a surface of the image-bearing component, a developing device for developing a latent image produced on the image-bearing component to produce a toner image, a cleaning device for removing residual toner remaining on the image-bearing component, and the like. As shown in Fig. 3, the process cartridge B according to the illustrated embodiment includes a charger 8, an exposure section 9, a developing device 10 for carrying out a developing process with toner, and a cleaning device 11 which are arranged around an electrophotographic photosensitive drum 7 as an image bearing member and which are enclosed in a case comprising a toner housing part 12, a developer housing part 13 and a cleaning housing part 14 to form a unit which can be detachably mounted as a process cartridge B on the frame 15 of the image forming apparatus.

The various components of the process cartridge B, namely the photosensitive drum 7, the charger 8, the exposure area 9, the developing device 10 and the cleaning device 11, are described in detail in this order.

(Photosensitive drum):

The photosensitive drum 7 according to the exemplary embodiment comprises a cylindrical drum base 7a made of aluminum and an organic photosensitive layer 7b coated on an outer peripheral surface of the drum base. As shown in Fig. 7, when the photosensitive drum 7 is attached to the cleaning case part 14 and a driving force of a driving motor 71 (see Fig. 59) of the image forming apparatus is transmitted to a helical gear 7c (5. Fig. 8A) fixed to a longitudinal end of the photosensitive drum 7, the drum 7 is rotated in a direction indicated by the arrow in Fig. 1 in accordance with the image forming operation.

Incidentally, as shown in the longitudinal section of Fig. 8A, the photosensitive drum 7 is rotatably supported by the cleaning case 14 by inserting a boss 7d1 of the gear flange 7d attached to one longitudinal end of the photosensitive drum into a bearing portion 14a of the case 14, by installing a metal shaft 21 (made of iron in the illustrated embodiment) into a hole in a resin helical gear 7c attached to the other end of the drum, and by firmly attaching the shaft 21 to the case 14. Further, the shaft 21 has an integrally formed shaft shank 21a and flange 21b, and is attached to the case 14 by fastening the flange 21b to the case 14 via screws 21c. Furthermore, the wheel flange 7d comprises a spur gear and serves to transmit the rotational force of the photosensitive drum 7 rotated by means of the helical gear 7c, which receives the driving force from the image forming device, to the transfer roller 4 so that the latter is rotated.

Furthermore, the metal shaft 21 is a conductive member, and another conductive member 22 (made of bronze phosphide in the exemplary embodiment) is arranged to engage an inner surface of the aluminum drum base 7a of the photosensitive drum at the end thereof into which the metal shaft 21 is inserted, so that contact is made with the conductive member 22 when the metal shaft 21 is inserted. Consequently, the photosensitive drum 7 is grounded to the image forming apparatus through the conductive member 22 and the metal shaft 21 as will be described later, that is, the conductive member 22 is, as shown in Fig. 9, attached to and fixed by projections 7c2 formed on an end surface of the flange portion 7c1 of the helical gear 7c, and has a hole or opening 22a into which the metal shaft 21 is to be inserted. In addition, a contact piece 22b having spring properties is also provided so as to project into the opening 22a. When the metal shaft 21 is inserted into the opening, it comes into contact with the contact piece 22b while exerting pressure thereon. In addition, the conductive member 22 is provided with two-pointed pawl parts 22c projecting in the left and right directions so that when the flange portion 7c1 is inserted into the photosensitive drum 7, the pawl parts 22c come into contact with the inner surface of the photosensitive drum 7.

In the image forming operation, the photosensitive drum 7 is rotated and the surface of the photosensitive drum 7 is uniformly charged by applying the DC and AC voltages to the charging roller 8 in an overlapping manner. Note that in order to uniformly charge the surface of the photosensitive drum 7, in this case, it is preferable that the DC and AC voltages are applied to the charging roller 8 in the overlapping manner and the frequency of the AC voltage is increased. However, if the frequency of the AC voltage exceeds about 200 Hz, there is a risk that a so-called "charging noise" due to the vibration of the photosensitive drum 7 and the charging roller 8 is increased.

Specifically, when the AC voltage is applied to the charging roller 8, an electrostatic attractive force is generated between the photosensitive drum 7 and the charging roller 8, and the attractive force is strong at the maximum and minimum values of the AC voltage, whereby the charging roller 8 is attracted toward the photosensitive drum 7 with elastic deformation. On the other hand, the attractive force is relatively weak at the middle value of the AC voltage, with the result that the charging roller 8 tends to separate from the photosensitive drum by the restoring force based on the elastic deformation. Consequently, the photosensitive drum and the charging roller 8 are vibrated at the frequency twice the frequency of the applied AC voltage. Furthermore, when the charging roller 8 is attracted to the photosensitive drum 7, the rotations of the roller and the drum are braked, so that the vibrations due to the sliding movement caused by the adhesion (like when a wet glass is rubbed with a finger) are generated; these vibrations cause the charging noise.

Therefore, according to the illustrated embodiment, in order to reduce the vibration of the photosensitive drum 7, as shown by the sectional views in Figs. 8A and 8B, a filler 7e formed of a rigid body or an elastic body is arranged in the photosensitive drum 7 at a central portion in the longitudinal direction thereof. The material of the filler 7e may be metal, e.g., aluminum or brass, or a ceramic material, e.g., cement or gypsum, or rubber, e.g., natural rubber, or the like. The material of the filler may be appropriately selected among them in consideration of productivity, workability, and the effects of mass and cost. Incidentally, in the exemplary embodiment, the filler 7e is made of aluminum having a mass of about 120 grams.

The shape or configuration of the filler 7e may be a solid cylinder or a hollow cylinder (in the illustrated embodiment, the filler is formed as a solid cylinder as shown in Fig. 8B). For example, the filler 7e having an outer diameter smaller by about 100 µm than an inner diameter of the photosensitive drum 7 is inserted into the hollow drum base 7a, the filler is attached to the photosensitive drum, that is, the gap between the drum base 7a and the filler 7e is kept at 100 µm at the maximum, and an adhesive (e.g., of the cyanoacrylate group, of the epoxy resin group, or the like) is applied to an outer surface of the filler or the inner surface of the drum base 7a so that the filler 7e is adhesively bonded to the inner surface of the drum base 7a.

As mentioned above, by providing the filler 7e in the photosensitive drum 7, the photosensitive drum 7 is stably rotated so that the vibrations due to the rotation of the photosensitive drum 7 during the image forming operation are suppressed. As a result, even if the frequency of the AC voltage applied to the charging roller 8 is increased, it is possible to suppress the charging noise.

(Charging device)

The charging device 8 serves to charge the surface of the photosensitive drum 7. In the exemplary embodiment, a charging method of the so-called contact type disclosed in Japanese Patent Laid-Open No. 63-149669 is used. In detail, as shown in Fig. 10, the charging roller 8 is rotatably mounted on the cleaning case part 14. The charging roller 8 comprises a metal roller shaft 8a, an elastic conductive layer around the roller shaft, an elastic high-resistance layer around the conductive layer, and a thin protective layer around the high-resistance layer. The elastic conductive layer is made of an elastic Rubber layer such as EPDM or NBR in which carbon powder is dispersed, and functions to direct the bias voltage toward the roller shaft 8a. Further, the elastic high-resistance layer is made of urethane rubber in which a small amount of conductive fine powder (e.g., carbon powder) is dispersed, and functions to prevent the abrupt reduction of the bias voltage by limiting the leakage current to the photosensitive drum 7 even when the charging roller having a high conductivity such as a pinhole is disposed in opposition to the photosensitive drum 7. Further, the thin protective layer is made of N-methyl-methoxyl nylon, and functions to prevent the deterioration of the surface of the photosensitive drum 7 when the plastic material of the elastic conductive layer and/or the elastic high-resistance layer comes into contact with the photosensitive layer.

The roller shaft 8a is attached to the housing part 14 via bearings 23 and 24 which are slightly displaceable towards the photosensitive drum 7, the bearings being loaded towards the photosensitive drum 7 by springs 25, so that the charging roller 8 is in contact with the photosensitive drum 7.

In the image forming operation, the charging roller 8 is rotated by the rotation of the photosensitive drum 7 while the DC and AC voltages are applied to the charging roller 8 in the overlapping manner as mentioned above so that the surface of the photosensitive drum 7 is uniformly charged. For this purpose, a metal contact member 26 having a spring property is engaged with one end of the metal roller shaft 8a, thereby enabling the voltage from the image forming apparatus to be applied to the charging roller 8.

Further, a regulating member 14b for suppressing the deformation of the contact member 26 is formed on the cleaning case part 14, so that even if any force directed to the left in Fig. 10 acts on the roller shaft 8a resulting from the falling of the process cartridge B or the like, the contact member 26 is prevented from plastically deforming by keeping the contact member 26 in abutment against the regulating member 14b. Further, since the regulating member 14b restricts the axial movement (to the left in Fig. 10) of the charging roller 8, the charging roller 8 is always held on the photosensitive drum 7.

On the other hand, the positioning of the other end of the loading roller 8 is effected by the bearing 24, i.e., the bearing 24 has, as shown in Fig. 10, a hook-shaped abutment part 24a formed integrally therewith. By abutting the other end of the roller shaft 8a of the loading roller 8 against the abutment part 24a, the axial movement of the loading roller 8 to the right (in Fig. 10) is restricted. The bearing 24 is made of polyacetal (POM), which has a good wear protection property and offers good sliding ability with respect to the metal roller shaft 8a.

As mentioned above, the two ends of the roller shaft 8a are abutted against the wear-protection bearing 24 and the contact element 26 to limit the axial movement of the charging roller 8, thereby preventing the charging roller 8 from contacting the housing part 14. If the axial movement of the charging roller 8 were to be limited by abutting the ends of the roller shaft 8a directly against the housing part 14, the housing part 14 would have to be made of a material that has good wear-protection properties with respect to the metal roller shaft 8a, e.g. polyphenylene oxide resin (PPO). In contrast, if the roller shaft 8a does not directly contact the housing part 14, as in the illustrated embodiment, it is not necessary to increase the wear-protection capability of the housing part 14. Thus, in the exemplary embodiment the housing part 14 can be made of polystyrene resin (PS) instead of PPO, which is cheaper, thereby reducing the manufacturing cost of the process cartridge B.

Incidentally, the material of the bearing 24 is not limited to polyacetal, but may be another material, e.g., nylon, as long as the material has the high wear protection ability with respect to the metal roller shaft 8a.

According to the illustrated embodiment, the voltage applied to the charge roller 8 to charge the photosensitive drum 7 has an AC component Vpp of about 1800 V and a DC component VDC1 of about -670 V, and the constant current control is carried out.

(Exposure part):

The exposure part or the exposure area 9 serves to form an electrostatic latent image on the photosensitive drum 7 uniformly charged by the charging roller 8 by causing the imaging light from the optical system 1 to be incident on the photosensitive drum. As shown in the perspective view of Fig. 4, the exposure part is formed by an opening area 9 formed in an upper surface between the developing housing part 13 and the cleaning housing part 14 and through which the imaging light passes. In other words, by providing a rectangular recess 9a in an upper surface 13r of the developing housing part 13 and by arranging an upper wall part 14n of the cleaning housing part 14 to cover a part of the recess 9a, the exposure area 9 is formed.

(Development facility):

The developing device 10 is explained below. The developing device serves to process the photosensitive drum 7 by the aforementioned exposure to make visible by toner to form a toner image. It is to be noted that although the image forming apparatus A may use both magnetic toner and non-magnetic toner, in the illustrated embodiment, an example is shown in which a process cartridge B containing magnetic toner as a one-component magnetic developer is mounted on the image forming apparatus.

The magnetic toner used in the development process uses polystyrene resin as the binding resin and preferably uses styrene/acrylic resin. Coloring material that can be added to the magnetic toner can be ordinary carbon black, copper phthalocyanine, finely divided antimony or the like.

Further, magnetic fine particles contained in the magnetic toner may be made of a material that can be magnetized in a magnetic field, which may be ferromagnetic metal powder, e.g. iron, cobalt, nickel, or an alloy or composition, e.g. magnetite or ferrite.

As shown by the sectional view in Fig. 3, the developing device 10 for forming the toner image with the magnetic toner has a toner container 10a for containing the toner, and a toner feeder 10b for feeding out the toner is arranged in the toner container 10a, the feeder being rotated in a direction indicated by the arrow. By using the fed-out toner and rotating a developing sleeve 10d having a magnet 10c therein, a thin toner layer is formed on the developing sleeve. When the toner layer is formed on the developing sleeve 10d, the triboelectric charging capacity sufficient for developing the electrostatic latent image on the photosensitive drum 7 can be obtained due to the friction between the toner and the developing sleeve 10d. Further, a developing blade 10e for regulating a thickness of the toner layer is provided so as to abut against the surface of the developing cylinder 10d.

In the exemplary embodiment, as the developing bias voltage, the AC component Vpp of about 1600 V and the DC component VDC2 of about -550 V are applied. Incidentally, when a value (VDC1. - VDC2) becomes larger than -50 V (becomes larger toward the plus side) in a relationship between the DC component VDC2 of this developing bias voltage and the DC component VDC1 of the aforementioned charging bias voltage, there is a risk that the fogging occurs.

The toner container 10a and the toner supply member 10b are formed in the toner housing part 12; whereas the developing cylinder 10d and the developing blade 10e are attached to the developer housing part 13. Stopper parts in the longitudinal direction of the housing parts 12 and 13 are connected to each other by ultrasonic welding so that these housing parts are integrally united.

The developing sleeve 10d on which the toner layer is formed and the photosensitive drum 7 are positioned so as to be spaced apart from each other by a small gap (about 250 µm). To this end, in the exemplary embodiment, as shown in the exploded perspective view of Fig. 11, abutment rings 10f each having an outer diameter larger than an outer diameter of the developing sleeve 10d by an amount corresponding to the above-mentioned gap are arranged near both axial ends of the developing sleeve 10d and outside a toner forming surface on the developing sleeve, these abutment rings abutting against the photosensitive drum 7 outside a latent image surface thereon.

Further, a gear (helical gear) 10g is fixed to one axial end of the developing sleeve 10d so that the gear 10g can be rotated together with the developing sleeve 10d. When the developer housing part 13 is adhesively connected to the cleaning housing part 14, the gear 10g meshes with the helical gear 7c of the photosensitive drum 7 so that the developing sleeve 10d can be rotated by the rotation of the photosensitive drum 7. In addition, the gear 10g meshes with a gear (not shown) connected to the toner supply member 10b so that the rotational force of the photosensitive drum 7 is transmitted to the toner supply member 10b.

With this arrangement, in the image forming process, by the rotation of the toner supply member 10b, the toner in the toner container 10a is supplied to the developing sleeve 10d so that the toner layer having a constant thickness is formed by the developing blade 10e on the developing sleeve 10d, and then the toner on the developing sleeve is transferred to the electrostatic latent image formed on the photosensitive drum 7. Incidentally, the formation of the toner layer on the developing sleeve 10d is effected by supplying the toner only to a carbon printing surface of the developing sleeve 10d and selecting a relationship between (a) the area of the photosensitive layer on the photosensitive drum 7 along its longitudinal direction (axial direction) and (b) the charging area influenced by the charging roller 8 and (c) the toner layer forming area (developing area) on the developing sleeve 10d so as to become (a) > (b) > (c).

The toner in the toner container 10a must also be prevented from leaking out between the developing cylinder 10d and the developer housing part 13. For this purpose, in the embodiment shown, as shown in Fig. 11, elastic seals 10h are provided to prevent toner leakage. at both end portions in the longitudinal direction of an opening 13a formed in the developer housing part 13 and through which the toner is supplied to the developing sleeve 10d, and further an elastic toner spreader plate 10i is mounted along a lower edge of the opening 13a to come into contact with the entire length of the developing sleeve 10d.

Here, a thickness of each toner leakage preventing seal 10h is equal to a thickness of a step portion formed on a lower edge 130 of the developer housing portion 13, so that when the toner leakage preventing seals 10h are adhered to the developer housing portion 13, upper surfaces of the seals 10h become flush with the lower edge 130. The coating plate 10i is adhered to an upper surface of the lower edge portion 130 by a double-sided adhesive tape (not shown). A length (in the longitudinal direction) of the coating plate 10i is longer than a length (in the longitudinal direction) of the opening 13a, and both end portions 2C of the coating plate in the longitudinal direction overlap with the toner leakage preventing seals 10h, while a free edge (in the width direction) of the coating plate is pressed against the peripheral surface of the developing cylinder 10 along its length with an appropriate pressing force.

The overlapping relationship between the coating plate and the toner leakage preventing seals will now be fully described. As shown in Fig. 12, since the thickness of the developing blade 10e is about 1.3 mm, the two end portions in the longitudinal direction of the developing blade 10e and the toner leakage preventing seals 10h cannot be arranged to overlap each other, with the result that a small gap 10k is caused between the end of the developing blade and each toner leakage preventing seal. The toner leakage preventing seals 10h are overlapped with the coating plate 10i in areas axially outside the gaps 10k.

When the toner layer is formed on the developing cylinder 10d, the toner tm passing through the gaps 10k is adhered to the developing cylinder 10d in a bulging state. However, since there are no toner leakage preventing seals 10h in the circulation areas of the toner tm, the toner tm is collected toward the toner container 10a by the coating plate 10i, so that the toner is prevented from leaking out of the cartridge.

Further, Fig. 13A shows a section along the line A-A in Fig. 11, while Fig. 13B shows a section along the line B-B in Fig. 11. From Fig. 13A, it can be seen that the toner leakage preventing seals 10h and the coating plate 10i are closely abutted with each other without being bent at the overlapped portions, and they become parallel to each other. If the coating plate 10i is bent and not in close contact with the toner leakage preventing seals 10h as shown in Figs. 14A and 14B, there is a risk that the toner will leak through if there is a gap between the seals and the plate. However, in the illustrated embodiment, since the coating plate 10i is not bent and is in close contact with the toner leakage preventing seals 10h, the leakage of the toner can be prevented.

Furthermore, in the illustrated embodiment, an abutment angle between the free edge portion of the coating plate 10i and the peripheral surface of the developing sleeve 10d is determined by the upper surfaces of the toner leakage preventing seals 10h, and there is no dispersion in the accuracy of the upper surfaces of the toner leakage preventing seals. Thus, there is substantially no dispersion in the initial setting accuracy of the abutment angle. In addition, since the coating plate 10i is used in the straight state, it is difficult for the abutment angle of the coating plate 10i to change over a long period of time. Thus, the toner stored in the toner container 10a Toner is difficult to escape between the coating plate 10i and the developing cylinder 10d.

Incidentally, regarding the leakage of toner, there is a danger that the toner leaks out between the developing blade 10e and the developing housing part 13. In order to avoid this, in the illustrated embodiment, as shown by the sectional views of Figs. 3 and 15, three longitudinal ribs 13b, 13c and 13d are formed on a part of the developing housing part 13 against which the developing blade 10e is abutted, so that the first and second ribs 13b, 13c abut against the developing blade 10e, while the third rib 13d is abutted against a blade fixing member 10j, e.g., a metal plate for attaching the developing blade 10e. Furthermore, a free edge of the second rib 13c which presses against the developing blade 10e is sharpened so that when the first rib 13b abuts against the developing blade 10e and the third rib 13d abuts against the blade fixing member 10j, the sharpened edge of the second rib 13c penetrates into the developing blade which is made of rubber with a thickness of about 1.3 mm.

Further, the sharpened edge of the second rib 13c is curved so that a longitudinally central part of the edge convexly projects slightly further than the two end portions of the edge. Now, when the developing blade 10e is attached to the developing housing part 13, since parts of the blade attachment member 10j near the two ends in the longitudinal direction are fixed by screws, the longitudinally central portion of the developing blade attached to the blade attachment member 10j can be bent. However, according to the above arrangement, even if the central portion of the blade is bent, since the edge of the second rib 13c is curved so that the central portion projects further than the two end portions (in a process cartridge capable of recording an image on an A4-size sheet, a projection of 10.1 - 0.5 mm is preferable), the rib 13c can be securely made to penetrate into the developing blade 10e along its entire longitudinal edge. Consequently, there is no gap between the developing housing part 13 and the blade 10e, thus preventing leakage of the toner between the blade and the developing housing part 13.

When a gap is caused between the second rib 13c and the developing blade 10e and the toner passes therebetween, since the third rib 13d abuts against the blade fixing member 10j, the leakage of the toner is prevented by the third rib. In particular, since the abutment area between the second rib 13c and the developing blade 10e is offset (i.e., not aligned) with respect to the abutment area between the third rib 13d and the blade fixing member 10j by an amount corresponding to the thickness of the developing blade 10e, it is difficult for the toner to leak out of the cartridge through both the abutment area between the second rib 13c and the developing blade 10e and the abutment area between the third rib 13d and the blade fixing member 10j.

In the developing device 10 according to the explained embodiment, a toner remaining amount detecting mechanism is further provided for detecting the toner remaining in the toner container 10a. As shown in Figs. 11 and 15, this mechanism comprises a metallic antenna wire 27 arranged in a connecting portion between the toner housing part 12 and the developer housing part 13 and in a toner passage from the toner container 10a to the developing sleeve 10d. By making the antenna wire 27 act as a first electrode and the developing sleeve 10d act as a second electrode, the voltage is applied between the first and second electrodes. In this case, if there is any toner between the electrodes, the electrostatic capacity therebetween will be increased; on the other hand, if there is no toner between the electrodes, the electrostatic capacity will be decreased.

Accordingly, by detecting the change in the electrostatic capacity by means of a control part 60 (5. Fig.59), it is possible to detect the amount of toner remaining. By comparing an electrical signal representative of the electrostatic capacity with a predetermined reference value, it is possible to detect a "zero toner" state. When the "zero toner" state is detected by the control part 60, for example, a lamp (as an alarm for replacing the process cartridge) is lit to inform an operator of the need to replace the process cartridge B. Incidentally, a concrete circuit for detecting the amount of toner remaining will be described later.

As for the connecting portion between the toner housing part 12 and the developer housing part 13, since the connecting portion in the lengthwise direction is welded, the toner cannot leak through this connecting portion. However, the connecting portions in the widthwise direction cannot be welded because, as shown in Fig. 11, an opening 12e formed in the toner housing part 12 is sealed by a cover film 28 to prevent the leakage of the toner into the toner container 10a of the process cartridge B, with a free end of the cover film 28 exposed to the outside through the connecting portion in the widthwise direction (between the housing parts 12 and 13), so that in operation, the operator can pull out the free end of the cover film 28 to expose the opening 12e. Therefore, in order to prevent leakage of the toner through the widthwise connecting portions between the toner housing part 12 and the developer housing part 13, toner leakage preventing seals 29 are arranged at the widthwise connecting portions.

However, because the voltage is applied to the antenna wire or conductor 27 as mentioned above, one end of the antenna conductor 27 must be extended outward through the connection area between the housing parts 12 and 13, and a contact piece 27a is formed at this end of the antenna conductor. The antenna conductor 27 for this purpose projects outward through the widthwise connected portion (between the toner housing part 12 and the developer housing part 13) where the toner leakage preventing seal 29 is adhered. In order to attach the antenna conductor 27 in this manner, as shown in Fig. 16, a recess 13e is formed in the developer housing part 13 at the connecting portion thereof, an adhesive 30, e.g. silicon, is applied to the surface of the recess 13e, and then the antenna conductor 27 is adhered to the developer housing part 13 by inserting the antenna conductor into the recess. As shown in Fig. 16, when the antenna conductor is inserted into the recess 13e, the adhesive applied to the surface of the recess 13e is squeezed out of the recess and bulges. If the adhesive 30 is cured in the bulged state, even if the toner leakage preventing seal 29 is adhered to the housing part 13, the seal 29 cannot be fully brought into close contact with the developing housing part 13, so that a gap is often generated. Although this gap 31 is small, since the toner includes fine particles, there is a risk that the toner leaks through the gap 31.

To avoid this, in the exemplary embodiment, as shown in Fig. 17A, after the antenna conductor 27 is inserted into the recess 13e having the adhesive 30 therein, the adhesive bulging out from the recess 13e is flattened or evened out along and on the antenna conductor 27 (while completely covering the antenna conductor 27) by a rod member or the like, as shown in Fig. 17B. Then, as shown in Fig. 17C, once the toner leakage preventing seal 29 is adhered to the housing part 13, the seal 29 can be brought into close contact with the surface (to be bonded) of the developer housing part 13 without any gap so that leakage of toner is completely prevented. Incidentally, when the bulged adhesive 30 is flattened as shown in Fig. 17B, new adhesive may be added to make the adhesive uniform and completely cover the antenna conductor 27.

The contact piece 27a of the antenna conductor 27 is also exposed to the outside. Therefore, there is a danger that the exposed part of the antenna conductor 27 is accidentally hit against any object by the operator during handling of the process cartridge B. Since the toner leakage preventing seal 29 is made of urethane foam with a thickness of about 4 mm and is elastic, when the exposed part of the antenna conductor 27 is hit against any object, there is a danger that, as shown in Fig. 18A, the antenna conductor 27 is displaced away from the developer housing 13. Also, in this case, a small gap 32 is created between the housing part 13 and the antenna conductor 27, resulting in toner leakage. To avoid this, in the exemplary embodiment, as shown in Fig. 18B, a bend 27b in an L-shape directed from the developer housing part 13 to the toner housing part 12 is formed on the antenna conductor 27 disposed in the connecting portion between the toner housing part 12 and the developer housing part 13. Since the gasket 29 having a thickness of about 4 mm is compressed to about 1 mm at this bend 27b, the elastic deformation does not occur. Consequently, when the impact acts on the exposed part of the antenna conductor as mentioned above, the antenna conductor 27 does not displace from the recess 13e of the developer housing part 13. Since the gap shown in Fig. 18A is not generated, the danger of the toner leakage can be avoided.

(Toner leakage prevention seal):

The toner leakage preventing seal 29 will be described below. The toner leakage preventing seals 29 are adhered to the two longitudinal end portions of the opening 12e of the toner housing part 12 by double-sided adhesive tapes. As shown in Fig. 11, on the upper surface of the toner leakage preventing seal 29, which is located on a side where the operator pulls out the cover sheet 28, a tear-preventing sheet 29a having a width smaller than a width of the seal 29 and a thickness of about 0.01 - 1 mm is adhered.

The reason why the tear-preventing film 29a is provided is as follows. Namely, in operation, the operator must pull out the cover film 28 by hand to expose the opening 12e of the process cartridge B. In this case, there is no problem if the operator pulls the cover film 28 in a film pulling-out direction (corresponding to the longitudinal direction of the opening 12e). However, as shown in Fig. 19, if the cover film is pulled out in an oblique direction with respect to the film pulling-out direction at an angle α, the cover film 28 can be pulled out in an oblique direction with respect to the film pulling-out direction. is pulled, as shown in Fig. 20, the width of the cover film 28 is reduced or wrinkled by contracting the film in one direction (upward direction in Fig. 20) with the result that the wrinkles of the film are rubbed against the toner leakage preventing seal 29, whereby a part (hatched area) of the seal 29 is often torn off. When the toner leakage preventing seal 29 is torn off or broken off, the toner leaks through the broken off part of the seal, so that the operator's hand is soiled or falling off into the image forming apparatus often occurs, whereby the recording medium carrying the record is smeared.

However, if, as in the embodiment shown, the tear-preventing film 29a is attached to the toner-preventing seal 29, past which the cover film 28 is pulled out, when the wrinkles are generated during the pulling out of the cover sheet, the seal 29 is prevented from being torn off because the tear-preventing sheet 29a protects the seal 29. Consequently, regardless of the direction along which the operator pulls out the cover sheet 28, the leakage of the toner can be prevented.

Furthermore, by providing the tear-preventing film 29a across the width of the seal 29 on one side of the opening 12e, the toner adhering to the film 28 while the cover film 28 is being pulled out is scraped off by the tear-preventing film 29a, thereby eliminating the possibility of the operator's hand being contaminated by the pulled-out film 28.

Incidentally, when the toner housing part 12 and the developer housing part 13 are welded together, since the toner leakage preventing seal 29 and the tear-out preventing film 29a are firmly clamped and held between the housing parts 12 and 13 at their longitudinal ends (upper and lower ends in Fig. 11), the film 29a is not moved away from the seal 29. The tear-out preventing film 29a is preferably made of a material which is strong against rubbing against the cover film 28, for example, polyethylene terephthalate or high-density polyethylene.

Further, when the tear-preventing film 29a having the width smaller than the width of the toner leakage-preventing seal 29 is adhered to the seal 29, as shown in Fig. 21, the adhesion position of the film 29a is located away from an edge 29b of the toner leakage-preventing seal 29 in the film pulling-out direction by a distance U. By doing so, while the cover film 28 is pulled out, the toner adhering to the film is more effectively scraped off by the edge 29b.

If the distance is set to about 5 mm or less, the tear-preventing effect of the toner leakage preventing seal 29 is not deteriorated during the pulling out of the cover film 28.

Incidentally, the tear-preventing film 29a may have a width not less than the width of the toner leakage-preventing seal 29 as mentioned above, so that the film is adhered to the entire surface of the seal 29.

(Various dimensions of the photosensitive drum and the like): With reference to Figs. 22 and 23, various dimensions of the photosensitive drum 7, the charge roller 8 and the developing sleeve 10d according to the illustrated embodiment and the positional relationship between these components will be explained below. However, the present invention is not limited to this example, but other dimensions and positional relationships can be appropriately applied.

(1) Number of teeth of the helical gear 7c 32;

(2) Diameter (D1) of the helical gear approximately 31.85 mm;

(3) Width (W1) of the helical gear 7c approximately 9.8 mm;

(4) Number of teeth on the wheel flange 7d 43;

(5) Diameter (D2) of the wheel flange 7d approximately 32 mm;

(6) Width (W2) of the wheel flange 7d approximately 5.6 mm;

(7) Length (L1) of the photosensitive drum 7: approximately 254 mm;

(8) Length (L2) of the photosensitive coated area on the photosensitive drum 7: about 250 mm;

(9) Diameter (D3) of the photosensitive drum 7 approximately 30 mm;

(10) Diameter (D4) of the metal shaft 21 of the photosensitive drum 7 about 10 mm;

(11) Length (L3) of the developing cylinder 10d approximately 246 mm;

(12) Length (L4) of the carbon printing surface on the developing cylinder 10d approximately 216 mm;

(13) Diameter (D5) of the developing cylinder 10d approximately 16 mm;

(14) Outside diameter (D6) of the counter bearing rings 10f approximately 16.5 mm;

(15) Length (L5) of the counter bearing rings 10f approximately 12 mm;

(16) Length (L6) of the counter bearing rings 10f approximately 9 mm;

(17) Outside diameter (D7) of the drum contact part of a counter bearing ring 10f approximately 16.7 mm;

(18) Thickness (E1) of the drum contact part of a counter bearing ring 10f approximately 0.3 mm;

(19) Width (W3) of the drum contact part of a counter bearing ring 10f approximately 4 mm;

(20) Number of teeth of the developer gear 10g 17;

(21) Diameter (D8) of the developer gear 10g approximately 18.1 mm;

(22) Width (W4) of developer gear 10g approximately 8.3 mm;

(23) Length (L7) of the charging bias contact element 49 approximately 7 mm;

(24) Width (WS) of the charging bias contact element 49 approximately 7.8 mm;

(25) Length (L8) of the development bias: contact element 48 about 6 mm;

(26) Width (W6) of development bias contact element 48 approximately 9.4 mm;

(27) Diameter (Dg) of the contact piece 27a of the antenna conductor 27 approximately 2 mm;

(28) Width (W7) of the contact piece 27a of the antenna conductor 27 approximately 15.5 mm;

(29) Length (L8) of the charging roller 8 approximately 25i mm;

(30) Length (L9) of the loading part (rubber part) of the loading roller 8 approximately 225 mm;

(31) Diameter (D10) of the charging roller 8 approximately 12 mm;

(32) Length (L10) of the roller shaft 8a approximately 12 mm;

(33) Diameter (Dli) of the roller shaft 8a approximately 6 mm.

Incidentally, the helical gear 7c and the developing gear 10g are helical gears, so that when the gear 7c is subjected to the driving force from the image forming apparatus, the photosensitive drum 7 mounted with play is subjected to the thrust force directed toward the gear 7c. Thus, the photosensitive drum 7 is displaced by the thrust force in the thrust direction with the result that the photosensitive drum abuts against the cleaning case part 14, thus the photosensitive drum is positioned in the direction of travel.

(Cleaning device):

The cleaning device 11 serves to remove the toner remaining on the photosensitive drum 7 after the toner image on the photosensitive drum 7 is transferred to the recording medium 2 by the transfer device 4. As shown in Fig. 3, the cleaning device 11 comprises a cleaning blade 11a which is in contact with the surface of the photosensitive drum 7 and is capable of scraping off the toner remaining on the drum 7, a discharge plate 11b arranged under the blade 11a to receive the scraped off toner and which is in contact with the surface of the photosensitive drum 7, and a waste toner container 11c to collect the received waste toner. Incidentally, the discharge plate 11b is slightly in contact with the surface of the photosensitive drum 7 so as to allow the passage of the excess toner past the photosensitive drum 7 and to discharge the toner removed from the photosensitive drum 7 by the blade 11a in a direction away from the surface of the photosensitive drum 7 (i.e., toward the excess toner container 11c).

Similarly to the developing blade 10e, the cleaning blade 11a is made of rubber material and the like and is bonded by a double-sided adhesive tape to a blade fixing member 11d which is attached by screws to the cleaning case part 14. Furthermore, the drain plate 11b is bonded to a drain plate bonding surface (an edge portion) 11c1 of the waste toner container 11c by means of a double-sided adhesive tape.

It is now necessary to prevent the excess toner collected in the excess toner container 11c from escaping between both longitudinal ends of the cleaning blade 11a and the opposite cleaning housing part 14. For this purpose, However, if the toner leakage preventing seals are not fully in close contact with the cleaning blade 11a, there is a risk that the toner leaks through a gap between the seal and the blade. Similarly, if the toner leakage preventing seals are not in close contact with the drain plate bonding surface 11d of the waste toner container 11c, there is a risk that the toner leaks through a gap between the seal and the bonding surface.

To prevent this, in the illustrated embodiment, as shown in Fig. 24, toner leakage preventing seals 11e are provided at both longitudinal ends of the cleaning blade 11a. The areas where the seals 11e are provided will be described in detail later. As shown in Figs. 24 and 25, the seals 11e are bonded to the two end portions of the waste toner container 11c, while the two longitudinal end portions of the cleaning blade 11a are bonded to the seals 11e. In addition, shielding members 11c3 are formed on an upper surface 11c2 of the waste toner container 11c to come into contact with inner surfaces of the corresponding seals 11e.

A method of attaching the toner leakage preventing seals 11e will now be explained. First, the cleaning blade 11a is attached to the cleaning case part 14, and then the seals 11e are attached in such a manner that edges S2 of the seals come into close contact with the two longitudinal edges S1 of the cleaning blade 11a, as shown in Fig. 26. In this case, if the width L1 of the seal 11e is larger than a distance L0 between the discharge plate bonding surface 11d and the cleaning blade 11a, a gap is generated between the lower edge T1 of the seal 11e and the discharge plate bonding surface 11d, causing leakage of toner. To prevent this, in the illustrated embodiment, embodiment, the distance L0 is set larger than the width L1 (L0 > L1) within the allowable tolerance, and the gasket ile is given a compression value X. In this case, the gasket ile must be adhered to the discharge plate bonding surface 11d while the lower edge T1 of the gasket is pressed against a hatched area T2 of the bonding surface; however, since the shielding members 11c3 are provided in the illustrated embodiment, the excess toner is prevented from leaking out during sliding transversely along the discharge plate bonding surface. Thus, it is possible to make the compression value X of the gasket ile substantially zero within the allowable tolerance.

(Housing parts or frames):

Next, the casing parts constituting the casing of the process cartridge B will be explained. As shown in Fig. 7, the casing of the process cartridge B is constituted by the toner casing part 12, the developer casing part 13 and the cleaner casing part 14. The toner casing part 12 and the developer casing part 13 are welded together as one piece to form a toner-developer casing set C. This toner-developer casing set C is joined to the cleaner casing part 14 in a manner described later to form the casing of the process cartridge B. Incidentally, the casing parts 12, 13 and 14 according to the exemplary embodiment are made of polystyrene resin by injection molding. When the casing members 12, 13 and 14 are made of a material having the charging characteristic close to that of the toner component, even if the toner is rubbed against the casing members during the image forming process, the abnormal charge due to the triboelectric charge is not generated, thereby preventing the deterioration in the image quality.

In this regard, in the illustrated embodiment, because as shown in the following Table 1 (literature "Surface Polymer and Electrostatics" Surface Film Molecule Design series 5 published by Japan Surface Science Associates, written by Yuji Murata), the polystyrene which is the material for the casing parts and the styrene/acrylic resin which is the toner component are both of the same styrene group and have the similar charging characteristic that does not generate abnormal charging even if the toner is rubbed against the casing parts. Incidentally, "styrene group" means a base material containing styrene at 60% or more. Table 1 (charging system)

As shown in Fig. 7, the toner container 10a and the toner supply member 10b are arranged in the toner housing part 12. Furthermore, as shown in Figs. 3 and 4, a plurality of elongated transverse ribs 12d are formed on an outer surface of the toner housing part 12, and these ribs form a grippable part. The widths of the ribs 12d formed on the outer surface of the toner housing part 12 are gradually changed to form the R-profile configuration as a whole. Since the operator can easily grip the toner housing part 12 without slipping when the process cartridge B is mounted or dismounted with respect to the image forming apparatus A, the operability for mounting and dismounting is thus improved.

Further, as shown in Fig. 7, the developing sleeve 10d and the developing blade 10e are provided on the developing housing part 13. Although, as shown in Fig. 11, the developing blade 10e is mounted in the housing part 13 by attaching the two end portions of the blade attachment member 10j to which the blade is bonded by screws, in the exemplary embodiment, before the attachment by screws, the blade attachment member 10j is positioned with respect to the developing housing part 13. For this purpose, positioning pins 13g are formed straight on a blade attachment surface 13f of the developing housing part 13, while holes formed in the blade attachment member 10j are fitted to the positioning pins 13g so that the attachment member 10j is positioned with respect to the housing part 13. Moreover, as shown in Figs. 7 and 11, positioning pins 13i are formed on an interface 13h of the developer housing part 13 to be connected to the toner housing part 12 (these positioning pins are arranged at the two longitudinal end portions of the developer housing part 13 as shown in Fig. 11), and these positioning pins are inserted into fitting holes 12c formed in the toner housing part 12, thereby defining the connection position between the developer housing part 13 and the toner housing part 12.

As shown in Fig. 27, in the exemplary embodiment, the construction is such that the blade attachment surface 13f and the joint interface surface 13h of the developer housing member 13 are parallel to each other. Thus, in the case of molding the developer housing member 13 by injection molding, since the positioning pins 13g for positioning the blade and the positioning pins 13i for positioning the toner housing member are parallel to each other, after the molding, merely by separating the mold halves 33 from each other in the left and right directions, the molded housing member can be separated from the mold halves without difficulty.

Furthermore, as shown in Fig. 7, the photosensitive drum 7, the charging roller 8, the cleaning blade 11a, the drain plate 11b and the waste toner container 11c of the cleaning device 11 are provided on the cleaning housing part 14. Incidentally, when the cleaning blade 11a is attached to the cleaning housing part, similarly to the attachment of the developing blade 10e mentioned above, both longitudinal end portions of a blade attachment member 11d to which the cleaning blade is adhered are attached to the housing part 14 by screws. Before being attached by the screws, however, the blade attachment member 11d is positioned with respect to the housing part 14. For this purpose, as shown in Fig. 28, positioning pins 14d are formed straight on a blade mounting surface 14c of the housing part 14, and holes (not shown) formed in the blade mounting member 11d are fitted onto the pins 14d so that the mounting member 11d is brought into the correct position with respect to the cleaning housing part 14. In this case, the construction is such that the blade mounting surface 14c is at right angles to a mold separation direction (indicated by arrows in Fig. 28) for mold halves 34. With this arrangement, since the direction of the projecting positioning pins 14d formed on the blade mounting surface 14c coincides with the mold separation direction for the mold halves 34, the construction of the mold halves 34 can be facilitated.

The drum shutter 35 shown in Fig. 3 is pivotally mounted on the cleaning housing part 14. The drum shutter 35 serves to open and close an opening through which the photosensitive drum 7 faces the transfer roller 4. As will be described later, the drum shutter is automatically opened as soon as the process cartridge B is mounted on the image forming apparatus A, and is automatically closed as soon as the process cartridge is dismounted from the image forming apparatus A.

(Welding between the toner and developer housing parts):

The welding between the toner housing part 12 and the developer housing part 13 will now be explained. The housing parts 12 and 13 are bonded to each other by ultrasonic welding. After the opening 12e of the toner housing part 12 is closed by the cover film 28, as shown in Fig. 29, the toner housing part 12 is inserted into a recessed part 75a of a receiving tool 75, and then a separable cover film pulling handle 12f formed integrally on the housing part 12 is bent downward. Then, the developer housing part 13 is superimposed on the toner housing part 12, after which the developer housing part 13 is subjected to the pressure of a pressing tool (holding tool) 76 from above. In this state, when the ultrasonic waves are applied to the toner housing part 12 and the developer housing part 13, ribs 13s (Fig. 7) formed on the connecting surface 13h of the toner housing part 12 are welded so that the housing parts 12 and 13 are connected to each other.

It is to be noted that when the ultrasonic waves are applied to the housing parts, the housing parts 12 and 13 tend to deform in their width direction (shown by arrows J in Fig. 29). However, in the embodiment explained, since longitudinal ribs 13t are provided on the developer housing part 13 as shown in Fig. 11, and because the blade fixing member 10j made of a metal plate is attached to the developer housing part, the developer housing part has sufficient strength to resist deformation. Moreover, because the toner housing part 12 has no reinforcing rib, the toner housing part has moderate strength and is generally liable to deformation. However, in the exemplary embodiment, as shown in Figs. 7 and 11, bent portions 12g are formed on the toner housing part 12 at both longitudinal edges thereof (upper and lower edges along the longitudinal direction of the opening 12e). A distance between the bent portions 12g is substantially equal to the width dimension L13 of the connecting interface 13h of the developer housing part 13 so that the interface 13h of the developer housing part 13 can be inserted between the bent portions 12g.

When the housing parts 12 and 13 are joined together by ultrasonic welding, the intermediate surface 13h of the developer housing part 13 is fitted between the angles 12g of the toner housing part 12, and the positioning pins 13i of the developer housing part 13 are fitted into the fitting holes 12c of the toner housing part 12. Therefore, the toner housing part 12 is hardly deformed by the vibrations generated during the ultrasonic welding process, so that deviation between the housing parts 12 and 13 is prevented. Namely, because the intermediate surface 13h of the developer housing part 13 is inserted between the bends 12g formed on the toner housing part 12 along the upper and lower edges thereof, even when the up-down vibrations are applied in the width direction of the toner housing part 12, the movement of the toner housing part 12 is controlled by the developer housing part 13, thus preventing the deformation of the toner housing part 12 and the deviation between the housing parts 12 and 13.

Because in the illustrated embodiment, when the housing parts 12 and 13 are welded together, all the housing parts are made of the same material (polystyrene resin), the welding and connection strength between the housing parts 12 and 13 is extremely increased.

Although, as mentioned above, an example was discussed for the embodiment explained, in which the positioning pins 13i of the developer housing part 13 are arranged only on one longitudinal edge of the developer housing part 13, such positioning pins 13i can also be designed on both longitudinal edges of the developer housing part 13. In this case, it is possible to prevent the deformation of the toner housing part 12 and the developer housing part 13 even more reliably during the welding process and to prevent the deviation between the housing parts 12 and 13 even more clearly.

If a plurality of positioning pins (not visible) of the developer housing part 13 and the fitting holes 12c (into which the pins are inserted) of the toner housing part 12 are arranged side by side in the longitudinal direction of the housing parts, as shown in Fig. 31, the deformation of the housing parts 12 and 13 and the deviation between the housing parts can be prevented more significantly. By doing so, the above-mentioned bends 12g arranged on the two broad side edges of the toner housing part 12 can be omitted.

(Design to facilitate assembly of the process cartridge)

In assembling the process cartridge B, the toner supply member 10b is mounted on the toner housing part 12, the opening 12e of the toner container 10a containing the toner is closed by the cover film 28, and the antenna conductor 27 is attached. Then, the developer housing part 13 is welded to the toner housing part 12. Then, the developing cylinder 10d and the like are mounted on the developer housing part 13. In this case, the toner-developer housing set C comprising the one-piece developer housing part 13 and the toner housing part 12 is securely placed on the mounting plate, and the various parts are mounted on the housing set C (see Fig. 33). As shown in Fig. 32A, in the illustrated embodiment, a fitting hole 12a is formed in the toner housing part 12 at a predetermined position, while a bottom 12b of the toner housing part 12 is made flat. Thus, by inserting a bracket 36a formed on the mounting plate 36 into the fitting hole 12a, the toner housing part 12 can be fixed without difficulty, thereby facilitating the assembly of the components such as the developing sleeve bd, the developing blade 10e and the like, resulting in an improvement in the operability of the assembly.

Similarly, the components such as the cleaning blade 11a and the like are assembled to the cleaning case 14. As shown in Fig. 32B, in the exemplary embodiment, a bottom of the cleaning case 14 is made flat, and a fitting hole 14e is formed in the bottom of the cleaning case. Accordingly, when the components such as the blade 11a and the like are assembled to the cleaning case 14, by inserting a mounting projection 37a formed on the mounting plate 37 into the fitting hole 14e, the cleaning case 14 can be easily fixed, thereby facilitating the assembly of the components such as the cleaning blade 11a and the like, resulting in an increase in the workability for assembly.

The automatic assembly will now be explained with reference to the accompanying drawings. First, regarding the assembly of the toner-developer housing set C, as shown in Fig. 33 with respect to the mounting plate 36 which is displaced in a direction indicated by the arrow by means of transport rollers 36b, in a step 1, the fitting hole 12a of the toner housing part 12 is set on the upstanding support 36a of the mounting plate 36, in a step 2, the developing blade 10e is mounted, and in a step 3, the developing blade 10e is fixed by screws. Then, in a step 4, the developing cylinder 10d is mounted, in a step 5, the developing cylinder 10d is fixed, and in a step 6, the toner-developer housing set C is picked up to bring it to a next operation. Moreover, after the toner-developer housing set C is accommodated, the mounting plate 36 is returned through a lower auxiliary line, after which step 1 is repeated again.

As mentioned above, by providing the fitting part (for insertion into the mounting plate 36) in the toner case part 12, it is possible to omit a clamping step for clamping the toner case part, thereby facilitating the assembly of the toner case part 12.

Regarding the assembly of the cleaning housing part 14 with respect to the mounting plate 37 which slides in a direction indicated by the arrow in Fig. 34 over transport rollers 37b, as shown in Fig. 34, in a step 1 the fitting hole 14e of the cleaning housing part 14 is placed on the mounting lug 37a of the mounting plate 37, in a step 2 the deflection plate 11b is glued, in a step 3 the cleaning blade 11a is mounted, and in a step 4 the cleaning blade 11a is fastened by screws. Furthermore, in a step 5 the photosensitive drum 7 is mounted, and in a step 6 the photosensitive drum is fixed. Finally, in a In step 7, the assembled cleaning housing part 14 is picked up to move it to the next step. After the cleaning housing part 14 has been picked up, the mounting plate 37 is then returned via a lower auxiliary line, whereupon step 1 is repeated again.

Thus, by providing the fitting part (for insertion into the mounting plate 37) in the cleaning housing part 14, similar to the toner-developer housing set C, it is possible to omit a clamping step for clamping the cleaning housing part 14, thereby facilitating the assembly of the cleaning housing part 14. Incidentally, as shown in Fig. 4, the cleaning housing part 14 is provided with holding recesses 140 which are gripped by the assembly machine in order to move the cleaning housing part between the stations during the automatic assembly process.

It should be noted that the assembly of the toner and cleaning housing parts 12 and 14, respectively, can be accomplished by means other than the automatic assembly machines. In simple assembly lines in which the housing parts are assembled manually using simple tools, for example, the work efficiency can be increased by using the assembly plates 36 and 37.

After the various components have been attached to the toner-developer housing set C, which comprises the toner housing part 12 and the developer housing part 13 as a unit, and to the cleaning housing part 14, the toner-developer housing set C is connected to the cleaning housing part 14. In this regard, the housings are often placed on a table. Before the toner-developer housing set C is combined with the cleaning housing part 14, the photosensitive drum 7 attached to the cleaning housing part 14 and the developer cylinder 10d attached to the developer housing part 13 are exposed to the outside. In this respect, there is a risk that these components come into contact with the table, whereby the components may be damaged. In particular, the photosensitive drum 7 is an extremely important component for carrying out the image forming process, and if the surface of the drum is damaged more or less, the image will be distorted or deteriorated, thereby deteriorating the image quality. Therefore, when the case to which the photosensitive drum 7 is attached or the case to which the developing sleeve 10d is attached is placed on the table in the assembling process etc., care must be taken during processing not to bring the photosensitive drum 7 or the developing sleeve 10d into contact with the table.

In the illustrated embodiment, as shown in Fig. 35, projecting parts 14f are formed on edges of an open end of the cleaning case part 14 to which the photosensitive drum 7 is assembled. The photosensitive drum 7 is arranged so that it is positioned inward (toward the cleaning case part 14) from a line connecting the free ends of the projecting parts 14f. With this arrangement, as shown in Figs. 35 and 36, when the cleaning case part 14 rests on the table, the projecting parts 14f come into contact with the table while the photosensitive drum 7 does not contact the table, thereby preventing damage to the surface of the photosensitive drum 7.

In a similar manner, as shown in Fig. 37, projecting parts 13j are formed on edges of an open end of the toner-developer housing assembly C to which the developing sleeve 10d is assembled. The developing sleeve 10d is arranged so that it is positioned inward (toward the developing housing part 13) from a line connecting the free ends of the projecting parts 13j. With this arrangement, when the developing housing part 13, which is integrally connected with the toner housing part 12, rests on the table, the projecting parts 13j come into contact with the table in system and the developing cylinder 10d does not touch the table.

In this way, since the developing sleeve 10d or the photosensitive drum 7 does not come into contact with the table even if the developer housing part 13 or the cleaning housing part 14 rests on the table, the accidental damage to the photosensitive drum 7 and the like can be prevented, thereby improving the assembly work. After the various components are mounted on the toner housing part 12, the developer housing part 13 and the cleaning housing part 14 in this way, the developer housing part 13 is connected to the cleaning housing part 14 to assemble the process cartridge B. The connection between the housing parts 13 and 14 is effected by connecting members 38 shown in Fig. 38. The connection between the housing parts 13 and 14 will now be explained.

According to Fig. 38, the connecting member 38 comprises a base part 38a having a threaded hole 38b through which a screw 39 is screwed, a vertical pin 38c and a spring holding part 38d, the parts 38c and 38d being arranged on either side of the threaded hole 38b. The vertical pin 38c projects downward from the base part 38a to prevent a connecting pin 13m (described later) of the developer housing part 13 from falling out. The spring holding part 38d is arranged parallel to the vertical pin 38c and is provided at its free end with a spring 38e which projects further downward than the vertical pin 38c. Cantilever arms 13k are provided at both longitudinal ends of the developer housing part 13, and the connecting pin 13m projects sideways from each cantilever arm 13k. Furthermore, a spring receiving recess 13n is formed in an upper surface of each cantilever arm 13k.

On the other hand, connecting grooves 14g, into which the connecting pins 13m are inserted, are provided in the cleaning housing part 14. A fastening part 14h is formed on each of the connecting grooves 14g. The fastening part 14h has a fitting opening 14i into which the vertical pin 38c of the connecting member 38, an internally threaded portion 14j into which the screw 39 is screwed, and a through hole 14k through which the spring 38e extends.

In order to connect the toner-developer housing set C and the cleaning housing part 14, as shown in Figs. 39A and 39B, the connecting pins 13m of the developer housing part 13 are deeply inserted into the corresponding connecting grooves 14g of the cleaning housing part 14, and then the connecting members 38 are firmly attached to the fastening members 14h. In other words, each vertical pin 38c of the connecting member 38 is inserted into the opening 14i, the spring 38e is passed through the through hole 14k and then compressed against the spring receiving recess 13n of the developer housing part 13. In this state, the screw 39 is screwed into the threaded hole 38b and fastened to the female thread portion 14j.

In this way, the toner-developer housing set C and the cleaning housing part 14 are connected to each other for relative pivotal movement around the connecting pins 13m, thereby completing the assembly of the process cartridge B. In a state where the housing parts 13 and 14 are connected to each other, the abutment rings 10f are abutted against the outer peripheral surface of the photosensitive drum 7, thereby determining the positions of the photosensitive drum 7 and the developing sleeve 10d. Further, by the urging forces of the compressed springs 38e, the developing sleeve 10d is pressed toward the photosensitive drum 7 (incidentally, in the exemplary embodiment, the urging force of the spring 38e is set to be about 2 kg to apply a force of about 1 kg to the developing sleeve 10d). Furthermore, when the toner-developer housing set C is connected to the cleaning housing part 14, the helical gear 7c provided at the end of the photosensitive drum 7 engages with the gear 10g provided at the end of the developing cylinder 10d.

In the connection structure between the toner-developer housing set C and the cleaning housing part 14 according to the exemplary embodiment, since the toner-developer housing set C can be mounted in a direction of the connection grooves 149, the connection pins 13m can be extended outward (these can be extended inward). Thus, the housing parts 13 and 14 can be positioned with respect to the longitudinal direction (thrust direction), thereby eliminating the need to provide thrust stoppers.

Furthermore, since the connecting members 38 are inserted and fixed from above, the toner-developer housing set C can be subjected to pressure at the same time as the connecting members 38 are fixed. In this regard, conventionally, after the toner-developer housing set was connected to the cleaning housing part, it was necessary to hook a tension spring to the housing parts in order to urge the housing parts toward each other, but this resulted in a space for arranging the tension spring being required and the operation for hooking the spring being troublesome. However, according to the exemplary embodiment, it is possible to eliminate the arrangement of such a tension spring and to save the installation space for the tension spring. Furthermore, when the housing parts are separated from one another by loosening the screws 39, the compression forces of the compressed springs 38e are eliminated, which enables the housing parts to be disassembled very easily due to the lack of thrust stops.

(Cartridge holder construction)

The structure for mounting the process cartridge B on the image forming device A is explained below.

As shown in Figs. 5 and 6 and mentioned above, the left guide member 17 with the first and second guide pieces 17a, 17b and the right guide member 18 with the first and second guide pieces 18a, 18b are formed on the frame 15 of the image forming apparatus. According to these guide members In Fig. 40 (which shows the left side surface of the cartridge) and in Fig. 4 (which shows the right side surface of the process cartridge B), the bearing part 14a and the shaft 21 (which are guided along the first guide pieces 17a, 18a) protrude from the left and right side surfaces of the cleaning housing part 14 of the process cartridge B essentially in left-right symmetry. Furthermore, projecting ribs 40 to be guided along the second guide pieces 17b and 18b are arranged above the bearing part 14a and the shaft 21 in left-right symmetry.

Furthermore, on the upper surface of the cleaning case 14, at both longitudinal ends thereof, pressure surfaces 41 are formed, which are subjected to pressure by pressure elements 19 attached to the frame 15 of the image forming apparatus. Furthermore, positioning recesses 42 are provided for receiving the stoppers 20 (see Fig. 5) and for positioning the stoppers. In addition, an auxiliary rib 43 protrudes from the right side surface of the cleaning case 14 above the protruding rib 40, as shown in Fig. 4. Furthermore, a pivoting member 35a for opening and closing the drum shutter 35 is provided. The pivoting member 35a is pivoted in response to the mounting and dismounting movement of the process cartridge B, whereby the drum shutter 35, which is connected to the pivoting member 35a, is opened and closed. The opening and closing of the drum shutter 35 will be described in detail later.

The assembly and disassembly of the process cartridge B with respect to the image forming apparatus A will now be explained with reference to Figs. 41 to 46. Since the left and right sides of the process cartridge B are guided in a similar manner by the left and right guide members 17, 18, only the right guide member 18 will be described for the sake of clarity and simplification of the explanation.

After the openable/closable cover 16 of the apparatus frame 15 of the image forming apparatus is opened, first, as shown in Fig. 41, the shaft 21 of the process cartridge B is placed on the first guide piece 18a while the protruding rib 40 is placed on the second guide piece 18b. Then, as shown in Fig. 42, the shaft 21 and the protruding rib 40 are slid along the guide pieces 18a, 18b to insert the process cartridge into the apparatus frame 15. As a result, the pressing surface 41 of the process cartridge B is subjected to pressure by the pressing members 19 of the frame 15, whereby the process cartridge B is inserted into the frame while being pressed against the second guide piece 18b.

Then, as shown in Fig. 43, when the projecting rib 40 extends beyond the second guide piece 18b, the process cartridge B is slightly rotated counterclockwise by the urging forces of the urging members 19, whereby the shaft 21 abuts against the first guide piece 18a. When the process cartridge B is further inserted, as shown in Fig. 44, the process cartridge B is further rotated counterclockwise with the result that the stoppers 20 of the frame 15 abut against the positioning recesses 42 of the process cartridge B. Thereafter, when the operator releases the process cartridge, the shaft 21 of the process cartridge B falls into the support part 18c by its own weight, as shown in Fig. 45. In this case, the stoppers 20 are fully engaged by the positioning recesses 42, with the result that the process cartridge B is mounted in the frame 15 of the image forming apparatus while being subjected to pressure by the pressure elements 19. Furthermore, in this case, the helical gear 7c of the photosensitive drum 7 engages with the drive gear (5. Fig.6) in the frame 15, thereby enabling the transmission of the driving force. Moreover, when the process cartridge B is mounted, the pressure forces of the pressure elements 19 against the process cartridge B are reduced by the lowering movement of the cartridge. B is relieved. Thus, the operator who has mounted the process cartridge B perceives the "snap" impression to easily recognize the fact that the process cartridge B has been positioned in the mounting position.

Incidentally, the stoppers 20 of the apparatus frame 15 and the positioning recesses 42 of the process cartridge B are arranged so that the abutment surfaces 20a, 42a thereof are substantially parallel to each other. Thus, the stoppers can be mounted on the frame in such a manner that the abutment surfaces 20a are substantially horizontal. Therefore, the design of the stoppers and the mounting of the stoppers on the frame 15 can be simplified or facilitated with the result that the dimensional error is unlikely to occur. Accordingly, it is a simple matter to correctly mount the process cartridge B on the frame 15 of the image forming apparatus.

Incidentally, a roller 19b is attached to each pressure element 19 so that the sliding resistance when the process cartridge B is slid while the pressure is applied to the pressure surfaces 41 by the pressure elements 19 is minimized. Further, although in the exemplary embodiment the pressure surfaces 41 of the process cartridge B, which are pressed by the rollers 19b, are formed into a flat configuration, these pressure surfaces may be formed into a ridged configuration to reduce the contact area, thereby further reducing the sliding resistance.

As is clear from the sectional view of Fig. 1 and the perspective view of Fig. 4, the upper part of the process cartridge B is made substantially flat, with the flat surface of the process cartridge being substantially parallel to the cartridge mounting direction. Thus, the cartridge receiving space in the frame 15 of the image forming apparatus can be can be minimized, while the space in the process cartridge B (e.g. spaces for the toner container 10a and the waste toner container 11c) can be used efficiently.

On the other hand, when the process cartridge B is removed, as shown in Fig. 46, the process cartridge B is slightly rotated in the counterclockwise direction (indicated by arrow a) so as to allow the projecting rib 40 to slip over the step portion 18b1 of the second guide piece 18b with the result that the process cartridge can be removed by pulling it out as it is. Incidentally, if the process cartridge B is excessively rotated in the counterclockwise direction, the auxiliary rib 43 (see Fig. 4) is abutted against the shutter cam control member 18d (while, with respect to the left guide member 17, the protruding rib 40 is abutted against the cartridge swing movement regulating guide 17d (see Fig. 5)), so that the counterclockwise rotation of the process cartridge is controlled. Furthermore, when the process cartridge is mounted, the auxiliary rib 43 provided on the right side of the process cartridge is inserted between the second guide piece 18b and the shutter cam control member 18d, while the protruding rib 40 provided on the left side of the cartridge is inserted between the second guide piece 17b and the swing movement regulating guide 17d. In this way, the movement paths when the process cartridge B is mounted and dismounted are further controlled, so that the mounting and dismounting of the process cartridge B is carried out more smoothly.

(Drum shutter opening/closing construction):

The drum shutter 35 is opened and closed depending on the mounting and dismounting movement of the process cartridge. The opening/closing operation of the drum shutter will now be explained.

As shown in Fig. 4, the drum shutter has the link arm 35b pivotally mounted around a shaft 35c, and the pivot member 35a is pivotally attached to the shaft 35c for movement together with the link arm 35b. Thus, when the pivot member 35a is pivoted, the link arm 35b is also pivoted, thereby opening and closing the drum shutter 35. Furthermore, a link pin 35d projects from the link arm 35b. By abutting the pivot member 35a and the link pin 35d with the shutter cam control part 18d, the drum shutter 35 is opened and closed. The opening and closing of the drum shutter is described in connection with the mounting of the process cartridge B in the image forming apparatus with reference to Figs. 41 to 45.

As shown in Figs. 41 to 45, the shutter cam control part 18d provided on the right guide member 18 has a first cam control surface 18d1 on which the link arm 35a abuts and a second cam control surface 18d2 on which the 2C link pin 35d abuts. An inclination angle of the first cam control surface 18d1 is substantially equal to that of the second guide piece 18b which guides the projecting rib 40 of the process cartridge B, and an inclination angle of the second cam control surface 18d2 is larger than that of the first cam control surface 18d1.

When the process cartridge B is inserted and pushed, as shown in Fig. 41, the pivot member 35a comes into contact with the first cam surface 18d1 of the shutter cam control part 18d, whereby, as shown in Fig. 42, the pivot member 35a is rotated about the shaft 35c. As a result, the link arm 35b is rotated to open the drum shutter; however, in this case, the drum shutter is not fully opened but remains in a so-called half-open state. When the cartridge B is further pushed in, as shown in Fig. 43, the rotation of the link arm 35b causes the release between the pivot member 35a and the first cam control surface 18d1 and at the same time the contact between the link pin 35d and the second cam control part 18d2. As soon as the assembly of the process cartridge B is completed, as shown in Fig. 45, the drum shutter 35 is completely opened so that the recording medium 2 transported under the cartridge is not obstructed by the drum shutter.

When the process cartridge B is pulled out from the state shown in Fig. 45 to remove the process cartridge B from the image forming apparatus A, the link pin 35d and then the pivot member 35a are brought into contact with the shutter cam control member 18d in an order opposite to the above-mentioned order by a spring force of a torsion coil spring 35e (5. Fig. 4) fixedly attached to the link arm 35b, so that the drum shutter door 35 is closed.

The above-mentioned drum shutter 35 serves to protect the photosensitive drum 7. In the exemplary embodiment, in addition to the drum shutter 35, the laser shutter member 46 (Fig. 1) is provided in the image forming apparatus A. The laser shutter member is a laser beam path blocking device for preventing laser light emitted from the optical system 1 to the photosensitive drum 7 from exiting the optical unit 1a (of the image forming apparatus) in an inoperative state of the apparatus.

(Laser beam path blocking device):

The construction of the laser beam path blocking device will now be explained. As shown in Fig. 47, the optical unit 1a is provided with an opening 1a1 through which the laser light is made incident on the photosensitive drum 7, and the laser shutter member 46 is formed of a metal plate bent so as to cover the opening 1a1. That is, the laser shutter member 46 comprises a shutter piece formed of the bent metal plate 46a and a pivoting member 46b arranged on the left side of the closure piece and formed integrally therewith. The laser closure member 46 is pivotably mounted on the frame 15 of the image generating device via shafts 46c.

Furthermore, in the vicinity of the left guide member 17, a guide arm 47 is pivotably mounted about a shaft 47a in order to guide the process cartridge B. The guide arm 47 has a free end piece which can come into contact with the pivoting member 46b of the laser shutter member 46 and is arranged in such a way that it abuts against the end face of the process cartridge B when the cartridge B is mounted in the frame 15 of the device.

With this arrangement, when the process cartridge B is installed while being guided by the left and right guide members 17, 18, an opening/closing member of the cartridge 8 presses against the link arm 47 in a direction indicated by arrow a in Fig. 47. As a result, the free end of the link arm 47 presses against the pivot member 46b of the laser shutter member 46, thereby rotating the shutter member 46a in a direction indicated by arrow b. Consequently, the opening 1a1 of the optical unit 1a is opened, allowing the laser light to be irradiated onto the photosensitive drum 7.

Furthermore, the shutter member 46 is constantly urged in a direction to close the opening 1a1 by a tension force of a tension spring 47b attached to the pivot member 46b of the laser shutter member 46. When the operator removes the process cartridge B from the image forming device A, the laser shutter member 46 automatically closes the opening 1a1 by the spring force of the spring 47b because the pressure force of the link arm 47 is removed.

Accordingly, except for the case where the process cartridge 8 is mounted in the image forming apparatus to enable the image forming operation, the laser light is prevented from being incident from the optical unit 1a onto the photosensitive drum and the like. Furthermore, since the pivot member 46b and the link arm 47 for opening and closing the laser shutter member 46 are arranged near the left guide member 17 and opposite to the right guide member 18, the space for installing these components can be effectively utilized. Consequently, the efficient utilization of space can be achieved and thus the apparatus can be made small-sized. Incidentally, in the exemplary embodiment, as shown in Fig. 48, the position where the projection 14m abuts against the link arm 47 is spaced from the side face of the cartridge by a distance Y1 of about 5 - 6 mm.

(Displacement of the tangible part):

When the operator mounts the process cartridge B in the image forming apparatus A, as shown in Fig. 48, the projection 14m (acting as an opening member) provided on the left shoulder portion (in the longitudinal or thrust direction) of the process cartridge B displaces the link arm 47 (for opening and closing the laser shutter member 46) provided on the frame of the apparatus. At substantially the same time, the metal shaft 21 (having a diameter X1 of about 10 mm and a protrusion value X2 of about 5 mm) projecting from the right side of the process cartridge B and acting as a drum grounding contact comes into contact with a grounding contact member (an electrical contact) 51 having a spring property and provided on the frame of the apparatus. Furthermore, the pivoting member 35a provided on the right side of the cartridge 8 abuts against the shutter cam control part 18d of the frame in order to open the drum shutter flap 35.

Consequently, when the cartridge B is mounted, the longitudinal left side of the cartridge B is subjected to a load that opposes the urging force of the spring 47b to open the laser shutter 46. On the other hand, the right side of the process cartridge B is subjected to a load for deforming the contact member 51 having the spring property due to the contact between the metal shaft 21 and the ground contact member 51 and a load for resisting the urging force of the torsion spring 35e to open the drum shutter 35. In the explained example, among the above loads, the load for opening the drum shutter 35 is the largest. As a result, the cartridge, when inserted, is subjected to the load that is displaced from a longitudinal center C2 of the cartridge B.

Thus, in the illustrated embodiment, as shown in Fig. 48, the ribs 12d are arranged so that the longitudinal center C11 of the ribs (which form the grippable part of the cartridge B) is offset from the longitudinal center C2 of the process cartridge B to a side on which the pivot member 35a of the drum shutter 35 and the metal shaft (conductive member) 21 are provided. In other words, in the exemplary embodiment, the longitudinal center C11 of the ribs 12d is offset from the center C2 of the longitudinal extension L11 (about 300 mm) of the process cartridge B by about 10 mm (the longitudinal center C11 of the ribs 12d is offset from a center of a recording medium conveying path when the process cartridge B is mounted in the image forming apparatus A by about 10 mm or it is shifted from a longitudinal center of the photosensitive drum 7 of the process cartridge B by about 10 mm).

With this arrangement, when the cartridge B is installed in the image forming apparatus A, as shown in Fig. 49, the operator grasps the right side from the longitudinal center C2 of the cartridge B, that is, a side on which the pivot member 35a of the drum shutter 35 is provided, to insert the cartridge into the apparatus body. in the longitudinal direction of the cartridge B, the side on which the pivot member 35a is located is subjected to a force slightly larger than that on the other side. Due to the displacement of the force, the load for opening and closing the drum shutter 35 is cancelled, whereby the cartridge B as a whole can be smoothly inserted into the image forming apparatus A without any play. Furthermore, since the ribs 12d are arranged parallel to the photosensitive drum 7 mounted in the longitudinal direction of the cartridge B, when the cartridge is inserted while gripping the ribs 12d, the longitudinal direction of the cartridge can be easily maintained perpendicular to the cartridge insertion direction, so that any play at the two longitudinal ends of the cartridge during the insertion thereof is easily eliminated.

Incidentally, although the grippable part may be formed by the ribs i2d as shown in Fig. 48, it may be formed by a recess 73 formed in the housing as shown in Fig. 50 or by a projection or ridge 74 formed on the housing as shown in Fig. 51. That is, the grippable part may have any configuration as long as the operator can comfortably grasp it.

Furthermore, although in the illustrated embodiment, an example has been explained in which the grippable part is arranged offset to the side where the pivoting member 35a of the drum shutter 35 and the metal shaft 21 are provided, the present invention is not limited to this example. If the urging force of the spring 47b of the laser shutter member 46 is strong and if the load counteracting the urging force of the coil spring 35e is stronger than the load counteracting the urging force of the spring 47b and the load for deforming the contact member 51, for example, the grippable part is arranged offset to a side where the projection 14m is provided.

In this way, the grippable part is displaced to a side on which the housing is subjected to the greater mounting resistance generated due to the abutment between the components of the image forming apparatus and the housing when the process cartridge is mounted in the image forming apparatus.

(Explanation of electrical contacts):

The electrical connection between various components when the process cartridge B is mounted on the image forming device is explained below.

When the process cartridge B is mounted on the image forming apparatus A, various contact members provided on the process cartridge 8 are brought into contact with various contact members provided in the frame 15 of the image forming apparatus, so that the process cartridge B is electrically connected to the image forming apparatus. As shown in Fig. 52, the contact piece 27a (made of stainless steel in the illustrated embodiment) as the conductive member provided at the end of the antenna conductor 27 for detecting the amount of toner remaining is exposed from the lower part of the developer housing part 13, while on the other hand, the development bias contact member 48 (made of stainless steel in the illustrated embodiment) as the conductive member for applying the development bias to the developer cylinder 10d is also exposed. Further, the charging bias contact member 49 (made of stainless steel in the illustrated embodiment) as the conductive member for applying the charging bias to the charging roller 8 is exposed from the lower part of the cleaning case part 14. Specifically, with respect to the photosensitive drum 7, the contact piece 27a of the antenna conductor 27 and the developing bias contact member 48 are arranged on one side, while the charging bias contact member 49 is arranged on the other side. Incidentally, the charging bias contact member 49 is formed integrally with the contact member 26 (Fig. 10).

Corresponding to these contacts, as shown in Fig. 53, with respect to the transfer roller 4, an antenna line contact member 50a with which the contact piece 27a of the antenna line 27 comes into contact when the process cartridge B is mounted and a developing bias contact pin 50b with which the developing bias contact member 48 comes into contact are arranged on one side in the recording medium conveying direction, while a charging bias contact pin 50c with which the charging bias contact member 49 comes into contact is arranged on the other side. Incidentally, as shown in Fig. 54, the contact pins 50b and 50c are attached to respective holding caps 50d so that they cannot slip out of the holding caps and protrude from the holding caps. The contact pins are biased upward by springs 50f and electrically connected by means of the springs 50f to the circuit pattern on an electrical substrate 50e to which the holding caps 50d are attached. Furthermore, of the contact elements 48 and 49 with which the contact pins 50b and 50c abut, the charging bias contact element 49 is formed in a curved shape having straight parts and a curved part connecting the straight parts so that the curvature is present on one side of the hinge 16a (Fig. 1) of the openable/closeable cover 16. Thus, when this lid 16 is closed around the hinge 16a in a direction indicated by the arrow c (Fig. 54) after the process cartridge B is mounted, the charging bias contact member 49, which is nearest to the hinge 16a and has the minimum radius of rotation, can be brought into contact with the contact pin 50c smoothly and effectively.

Furthermore, the shaft 21 supporting one end of the photosensitive drum 7 is made of metal, and the photosensitive drum 7 is grounded via the metal shaft 21. For this purpose, as shown in Figs. 6 and 48, a grounding contact member 51 comprising a leaf spring, which is grounded via a chassis of the frame 15 and the like, is provided on the guide piece 18a of the right guide member 18, on which the shaft 21 is arranged when the process cartridge B is mounted, and in the mounted state of the cartridge, the shaft 21 is in contact with the grounding contact member 51.

Referring to Fig. 22 and Fig. 52, the arrangement of the electrical contacts will now be explained. As shown in Fig. 22, the contacts 48, 49 are arranged on the side of the photosensitive drum 7 opposite to the side on which the helical gear 7c is provided, and the other side (on which the helical gear 7c is provided) of the photosensitive drum 7 is provided with the metal shaft 21 as the drum grounding contact. In a direction perpendicular to the longitudinal direction of the photosensitive drum 7, i.e., in the recording medium conveying direction, the developing bias contact member 48 is arranged on one side of the drum (side facing the developing device 10), while the charging bias contact member 49 is arranged on the other side (side facing the cleaning device 11). The metal shaft 21 as the drum grounding contact protrudes from the housing part 14 and is positioned on a rotation axis line of the photosensitive drum 7.

Furthermore, the developing bias contact element 48 and the charging bias contact element 49 are arranged along a line with respect to the longitudinal direction of the photosensitive drum 7 and are arranged on both sides of the gear flange (spur gear) 7d and the photosensitive drum 7. In addition, the contact elements 48, 49 are positioned inward of the outer end face of the gear flange 7d in the longitudinal direction of the photosensitive drum 7. By this arrangement, it is possible to reduce the longitudinal dimension of the process cartridge 8 and thus to make the process cartridge smaller.

In addition, as mentioned above, the charging bias contact element 49 is curved outward, that is, the contact member 49 has the straight part which becomes a leading part when the process cartridge is mounted and is curved from the straight part. With this arrangement, when the process cartridge B is mounted in the image forming apparatus A, even if the deviation in the abutment angle occurs between the charging bias contact member 49 and the charging bias contact pin 50c of the image forming apparatus, this deviation can be absorbed so that the charging bias contact member 49 abuts against the charging bias contact pin 50c securely and effectively. Although the charging bias contact member 49 is arranged forward when the process cartridge B is mounted in the image forming apparatus A, the contact member 49 and the contact pin 50c are not damaged during the cartridge mounting process.

Furthermore, the contact piece 27a of the antenna conductor 27, in order to detect the amount of toner remaining in the container 10a of the developing device 10, is arranged on the same side as the developing bias contact element 48 with respect to the longitudinal direction of the photosensitive drum 7 and is further spaced than this contact element 48 on one side of the drum 7 (towards the developing device 10) from this drum 7.

Since the above-mentioned arrangement of the contacts separates the charging bias contact member 49 from the metal shaft 21 as the grounding contact, there is no danger of ungrounded capacitance between the contacts, so that the charging voltage is stabilized to avoid the charge discrepancy. Namely, if the drum grounding contact is arranged close to other contacts, the ungrounded capacitance is generated between the wiring and contacts arranged around the drum grounding contact and these other contacts, with the result that the AC voltages used for developing, charging and toner remaining amount detection do not function properly. In particular, Because the constant current control is effected, in the case of the charging roller which is in contact with the photosensitive drum 7 to charge it, if the AC voltage fluctuates due to the disordered capacitance, there is a risk that the image is deteriorated. In contrast, by arranging the contacts as in the illustrated embodiment, the ungrounded capacitance can be eliminated, thereby maintaining the AC voltage stable or normal, thereby eliminating the charge discrepancy.

Furthermore, since the developing bias contact member 48 and the charging bias contact member 49 are arranged on both sides with respect to the photosensitive drum 7, the electrical interference between these contacts can be avoided.

In view of the above, in the present embodiment, when assembling the process cartridge B, the metal shaft 21 which projects outwardly with respect to the axial direction of the drum 7 and supports the photosensitive drum 7 is mounted in the cleaning case part 14, while the contact member 49 for charging bias is mounted on the opposite side of the metal shaft 21 with respect to the axial direction of the drum. Further, the contact member 48 for developing bias is mounted on the toner-developer case set C which supports the developing device. This contact member 48 is arranged in the axial direction of the photosensitive drum 7 when the cleaning case part 14 and the toner-developer case set C are connected to each other. Thereafter, the housing part 14 and the housing set C are combined to assemble the process cartridge 8.

(Toner remaining amount detection and cartridge insertion detection circuits):

The following describes the determination of the remaining toner quantity and the determination of the process cartridge capacity in this apparatus. As mentioned above, in this apparatus, the amount of toner remaining in the process cartridge B is detected based on the change in electrostatic capacity between the antenna conductor 27 provided on the cartridge and the developing sleeve 10d. For this purpose, a circuit shown in Fig. 55 is provided.

In the circuit shown in Fig. 55, the developing cylinder 10d and the antenna conductor 27 are equivalent capacitances. A high voltage power source HV applies a rectangular wave alternating voltage (Vpp = about 1600 V) to the developing cylinder bd. The high voltage from the high voltage power source HV has the rectangular rising edge and the rectangular falling edge, and it is detected as the differential waveform ANT by the electrostatic capacitance between the developing cylinder 10d and the antenna conductor 27 and the resistors R1, R2. Incidentally, a diode D1 is a clamp diode with the minus output. The derived waveform ANT is voltage-divided by the resistors R1, R2 and rectified in its peak value and converted into a direct current signal by a first extremum holding circuit, which comprises an operational amplifier OA1, a diode D2 and a capacitor C1. A resistor R3 is used to discharge the capacitor C1.

The electrostatic capacitance between the developing cylinder 10d and the antenna conductor 27 depends on an amount of toner present between the developing cylinder 10d and the antenna conductor 27, that is, since when the toner is present between the two conductors, the dielectric constant between the conductors becomes larger, the electrostatic capacitance between the conductors is increased. Accordingly, when the amount of toner is reduced, because the dielectric constant between the conductors becomes smaller and the electrostatic capacitance also becomes smaller, the voltage detected by the first extremum holding circuit is lowered since the amount of toner is reduced.

On the other hand, the output from the high voltage power source HV is supplied to the developing cylinder 10d and also to a differential circuit consisting of a standard capacitor C2, a resistor R4, a resistor R5 (regulating resistor) and a resistor R6. A diode D3 is a clamp diode having the minus output. The derived waveform detected by the regulating resistor R5 is converted into a DC signal by a second peak hold circuit comprising an operational amplifier OA2, a diode D4, a capacitor C3 and a discharge resistor R7. The regulating resistor R5 is adjusted so that the output from the second peak hold circuit becomes a desired reference value (about 2.7 V in the illustrated embodiment).

The output (potential of capacitor C1T value corresponding to the remaining toner amount) of the first extremum holding circuit and the output (potential of capacitor C3T reference value) of the second extremum holding circuit are compared by a comparator C01, from which a signal representative of the remaining toner amount is output. Accordingly, when the adequate amount of toner remains between the developing cylinder 10d and the antenna conductor 27, the potential of the capacitor C1 is higher than the potential of the capacitor C3, and the output of the comparator C01 becomes high. When the amount of toner between the developing cylinder 10d and the antenna conductor 27 is reduced, the potential of the capacitor C1 is reduced. If the potential of the capacitor C1 is lowered below the potential of the capacitor C3, the output of the comparator becomes low. Therefore, it is possible to determine the remaining toner amount based on the output of the comparator C01.

In the embodiment in question, it is also determined whether the process cartridge B is mounted in the image forming apparatus A or not. Namely, in the circuit shown in Fig. 55, when the potential of the capacitor C1 is less than a reference potential E (about 1 V in the illustrated embodiment), the output of a comparator CO2 assumes the low level, thereby judging that the process cartridge B is not mounted in the image forming apparatus A.

For example, when the power source is turned on, the controller for the image forming apparatus outputs the alternating current of the rectangular wave form from the high voltage source HV to the developing cylinder 10d. However, if the process cartridge B is not mounted in the image forming apparatus, since the photosensitive drum 7, the developing cylinder 10d and the antenna conductor 27 are not present in the circuit of Fig. 55, the signal is not input to the operational amplifier 0A1. In this case, therefore, the potential of the capacitor C1 becomes zero. Thus, by setting the reference potential E to the plus voltage with a certain margin from the zero level and to the potential lower than the potential of the capacitor C1 when the toner in the cartridge is used up, it is possible to detect the presence/absence of the process cartridge B.

A voltage relationship between the detection level for the presence of the remaining toner and the detection level for the presence of the mounted cartridge is shown in Fig. 56. A detection reference voltage (potential of the capacitor C3) for the presence/absence of the remaining toner may be set to an alarm level in Fig. 56 to inform the amount of toner insufficient to perform recording. Incidentally, in the illustrated embodiment, the reference voltage is set by adjusting the variable resistor R5 (at the time of manufacture) to the electrostatic capacity (about 7.5 pF) corresponding to the case where the toner of about 20 grams is present between the developing sleeve 10d and the antenna conductor 27. Further, the detection reference voltage The presence/absence of the mounted cartridge can be obtained by dividing the voltage of the power source by a resistor/resistors.

Although in the circuit of Fig. 55 the comparator CO2 was used to detect the presence/absence of the mounted cartridge, inverters IN1, IN2 having the appropriate slice level may be used instead of this comparator as shown by a circuit in Fig. 57. In this case too, it is necessary to adjust the detection voltage level from the antenna conductor 27 through the resistors R1, R2, R4, R5 and R6 so that the outputs of the inverters IN1, IN2 do not assume the low levels when there is no toner in the cartridge.

Furthermore, regarding the detection of the presence/absence of the mounted cartridge, if, as shown in Fig. 58, the output of the capacitor C1 is supplied to the controller via a buffer amplifier BA and the A/D conversion is effected, the detection becomes more reliable.

(Control part):

Next, the control system of the image forming apparatus A will be briefly described with reference to a functional block diagram shown in Fig. 59.

In Fig. 59, a control part 60 for controlling the entire image forming apparatus includes a CPU such as a microcomputer, a ROM for storing a control program for the CPU and various data, and a RAM used as a work area for the CPU and capable of temporarily storing various data.

The control part 60 receives signals from a sensor set 61 including a sheet jam sensor and the like. Furthermore, the control part receives a signal from a toner remaining amount detecting device 61a which detects the toner remaining amount in the cartridge based on the change in the electrostatic capacity between the developing cylinder 10d and the antenna conductor 27. Furthermore, an image signal is input to the control part 62 from a host 62 such as a computer, a word processor or the like.

Based on this information, the control part 60 controls various processes such as exposure 63, charging 64 (charging roller 8 and the like), developing 65 (developing cylinder 10d and the like), transferring 66 (transfer roller 4 and the like) and fixing 67 (fixing roller 5b and the like), and transporting 68 of the recording medium (alignment rollers 3d1, 3d2, discharge rollers 3f1, 3f2 and the like). In addition, the control part controls the drive of a main drive motor 71 via a counter 70 in order to count the number of pulses to be applied by the control part to a driver circuit 69.

Furthermore, in the illustrated embodiment, the control part 60 receives a signal representative of "zero toner" which is generated as a result of the toner remaining amount detection, and triggers the alarm 72 for the replacement of the process cartridge (for example, by turning on a lamp or a buzzer).

(Image generation process):

The following describes the image forming operation that is performed after the process cartridge B is mounted in the image forming apparatus A.

When the recording medium 2 is mounted on the sheet supply tray 3a shown in Fig. 1 and the mounting of the recording medium is detected by a sensor (not shown) or when the cassette 3h containing the recording medium 2 is inserted and the copy start button is pressed, the peel roller 3b or 3i starts to rotate and the separating roller pair 3c1, 3c2 and the alignment roller pair 3d1, 3d2 are rotated to 2 to the image forming station. In strict accordance with the feeding timing of the pair of alignment rollers 3d1, 3d2, the photosensitive drum 7 is rotated in the direction indicated by the arrow shown in Fig. 1, and by applying the charging bias to the charging roller 8, the surface of the photosensitive drum 7 is uniformly charged. Then, the laser light corresponding to the image signal is made incident on the photosensitive drum 7 from the optical system 1 through the exposure region 9, so that a latent image is formed on the drum in accordance with the illumination.

Simultaneously with the formation of the latent image, the developing device 10 of the process cartridge B is operated to rotate the toner supply member 10b, thereby feeding the toner in the toner container 10a to the developing cylinder 10d so that the toner layer is formed on the cylinder 10d. By applying the voltage having the same polarity and the same potential as the charge polarity of the photosensitive drum 7 to the developing cylinder 10d, the latent image on the photosensitive drum 7 is made visible as the toner image. The recording medium 2 is passed between the photosensitive drum 7 and the transfer roller 4, and by applying the voltage having the polarity opposite to that of the toner to the transfer roller 4, the toner image on the photosensitive drum 7 is transferred to the recording medium 2. After the transfer operation, the photosensitive drum 7 is further rotated in the direction indicated by the arrow in Fig. 1, whereby the residual toner remaining on the photosensitive drum 7 is scraped off by the cleaning blade ha, and the scraped toner is collected in the waste toner container 11c.

On the other hand, the recording medium 2 onto which the toner image has been transferred is fed to the fixing device 5, where the toner image is fixed to the recording medium by heat and pressure. 2. Then, the recording medium 2 is discharged onto the discharge section 6 by the discharge rollers 3e, 3f1, 3f2. Incidentally, as to the fixing means, while heat fixing was used in the embodiment explained, any other fixing means, eg pressure fixing type, may be used.

(Recycling of the process cartridge):

Next, the recycling of the process cartridge according to the above-described embodiment will be described. In the past, when the toner in the process cartridge was used up, the process cartridge was discarded. Thus, reusable parts such as rollers were also discarded together with the process cartridge. However, recently, in view of protecting the environment on earth, various electrical and electronic equipment is not discarded as usual, but such equipment is recycled (remanufactured or reused) from the viewpoint of saving resources, saving energy and reducing dust.

Thus, in the process cartridge according to the illustrated embodiment, since such parts as the charging elements, developing elements or cleaning elements each have a long life, they can still be used after the toner in the cartridge is used up. Therefore, recently, the cartridges in which the toner has been used up have been collected and the reusable parts have been recycled.

The procedure for recycling the process cartridge is now described. This procedure for recycling the process cartridge includes the following steps:

(1) Collect, (2) Sort, (3) Disassemble, (4) Select, (5) Clean, (6) Inspect, and (7) Reassemble. These steps are explained in detail below.

(1) Collect:

The used process cartridges are collected in a collection center with the assistance of consumers and maintenance personnel.

(2) Sort:

The used process cartridges collected in various collection centers are transported to a cartridge recycling company. The collected cartridges are sorted based on their respective types.

(3) Decomposition:

The sorted process cartridges are disassembled to remove parts.

(4) Selection:

The retrieved parts are inspected to select or sort them into reusable parts and non-reusable parts that have been damaged or have expired.

(5) Cleaning:

Only the parts that passed the selection process are cleaned so that they can be reused as new parts.

(6) Testing:

After cleaning, the parts are checked to see whether they can satisfactorily restore their functions and be used again.

(7) Reassembly:

A new process cartridge is reassembled using the parts that have passed the inspection. In the recycling, the charging roller 8, the developing cylinder 10d and the like are reused in their reassembly, while the casing parts 12, 13, 14 are crushed to recover their material. If the casing parts 12, 13, 14 are made of different materials, these casings are crushed together. then the different materials are mixed, thereby deteriorating the mechanical property of the material being recovered. Therefore, each of the casing members 12, 13 and 14 must be crushed separately or independently. However, in the above-mentioned case, since the toner casing member is welded to the developer casing member, these casing members must be separated from each other by a cutting process, which makes the recycling process cumbersome. However, in contrast to this, according to the exemplary embodiment as mentioned above, since the toner casing member 12, the developer casing member 13 and the cleaner casing member 14 are made of the same material (polystyrene resin), even if these casing members 12, 13 and 14 are crushed together to obtain pellets, the mechanical property of the material is not deteriorated, thereby improving the recycling process.

Furthermore, in the illustrated embodiment, since the polystyrene resin which is the material for the casing members is the same material as the toner component (both are of the styrene group), even if the casing members are crushed in a state where the cleaning of the used cartridge is incomplete and the toner still adheres to the casing members, the mechanical property of the material is not deteriorated unlike the case where the different materials are mixed.

However, the cleaning case member 14 must have the mechanical strength sufficient to support the photosensitive drum 7 and the like. However, if, as in the illustrated embodiment, the cleaning case member 14 is formed of polystyrene resin, which is the same material such as that of the toner-developer housing set C, the mechanical strength of the cleaning housing member is weaker than that of a cleaning housing member made of polyphenylene oxide (PPO) or polyphenylene ether (PPE). In this respect, as shown in Fig. 60, the cleaning housing member 14 in the exemplary embodiment is provided with an upper wall piece 14n (Figs. 4, 7 and 47 - 51) to cover an upper part of the photosensitive drum 7 between the two side walls 14p (of the housing member 14) supporting the rotary shaft of the photosensitive drum 7, thereby reinforcing the side walls 14p.

Furthermore, in the waste toner container 11c, partition walls 14q are provided to divide the interior of this container 11c into a plurality of chambers, and reinforcing ribs 14r are formed on the walls of each chamber on that side so that the cleaning case member is stiffened. Incidentally, the partition walls 14q restrict the accidental longitudinal movement of the toner contained in the waste toner container 11c, thereby preventing the waste toner from leaking out of the waste toner container 11c. By stiffening the cleaning case member 14 as mentioned above, even if the cleaning case member 14 is made of the same material (polystyrene resin) as that of the toner-developer case set C, the sufficient mechanical strength can be obtained.

[Other embodiments]

Further embodiments of various parts of the above-mentioned process cartridge and the above-mentioned image forming apparatus will be explained below.

(Charging device)

Although in the above-mentioned embodiment, an example has been described in which the axial displacement movement of the loading roller 8 is regulated by abutting one end of the roller shaft 8a against the abutment part 24a of the bearing 24 , as another embodiment, as shown in Figs. 61 and 62, one end of the roller shaft 8a may be supported by a bearing 52 having a cylindrical bore 52a. With this arrangement, when the roller shaft 8a is thrust in a direction indicated by the arrow in Fig. 61, an end surface of the roller shaft 8a is brought into abutment against a bottom surface 52b of the bore 52a, thereby positioning the roller shaft. Accordingly, this arrangement can achieve the same advantage as that of the previous embodiment. Incidentally, the bearing 52 is preferably formed of a material having good sliding property with metal, e.g., polyacetal, similar to the bearing 24 in the previous embodiment.

Further, as shown in Fig. 63, a side cutout 52c may be formed in the bearing 52, and the roller shaft 8a is forcibly inserted into the bearing with elastic deformation of the cutout 52c. With this arrangement, the ability to assemble the charging roller 8 is improved. Furthermore, if the cutout 52c is oriented to face downward upon mounting of the process cartridge B, even if a small amount of machining chips remains in the cylindrical bore 52a, since such machining chips fall out through the cutout 52c and are removed from the bore 52a, it is possible to stably rotate the roller shaft 8a in the bore 52a.

Furthermore, although in the above-mentioned embodiments, an example has been explained in which one end of the roller shaft 8a is supported by the bearing 24 or the bearing 52, the rotary shaft of the developing sleeve 10d and the like may be supported by the bearing 24 or 52.

Furthermore, in the first embodiment, the regulating member 14b was provided to prevent the plastic deformation of the contact member 26 when the roller shaft 8a was displaced; as another embodiment, as shown in Fig. 64 a rib 53 as a regulating member is provided on the cleaning case part 14 and the contact member 26 is fixed to the rib 53 by caulking under heat or the like. With this arrangement, even if the charging roller 8 is subjected to a force P shown by the arrow in Fig. 64, the contact member 26 is pressed against the rib 53, thereby preventing further deformation of the contact member. Thus, in operation, even if the cartridge B falls during its transportation, generating the force P, it is possible to prevent damage to the contact member 26.

Further, as shown in Fig. 65, a buffer 54 made of rubber or the like may be attached to a side surface of the rib 53 by a double-sided adhesive tape so that the buffer is interposed between the rib 53 and the contact member 26. With this arrangement, even if the charging roller 8 is subjected to a force shown by the arrow P, the plastic deformation of the contact member 26 can be prevented by means of the buffer 54. If the end portion of the contact member 26 is not brought into contact in parallel with an end surface of the rotating roller shaft 8a, the contact member 26 is brought into contact eccentrically with the end surface of the roller shaft 8a, thereby causing vibration and/or noise. However, in this embodiment, since the buffer 54 is provided, the vibration can be suppressed, thereby preventing the generation of noise.

(Development facility):

Although in the above-mentioned first embodiment, the three ribs 13b, 13c, 13d were formed on the developing housing part 13 and the sharply tapered end of the second rib 13c was pressed into the developing blade 10e as shown in Fig. 15, the end of the second rib need not necessarily be wedge-shaped and, for example, as shown in Fig. 66, this end of the second rib 13c may be sharpened in an arrowhead shape, wherein the Free end of the rib 13c can be pressed strongly against the developer blade 10e.

Further, in the first embodiment, as shown in Fig. 18, the bent portion 27b was formed in the antenna conductor 27 so that the antenna conductor 27 would not slip out of the recess 13e of the developing housing part 13 when an impact is applied to the exposed portion of the antenna conductor 27. However, the configuration of the bent portion 27b is not limited to that shown in Fig. 18, but may be semicircular as shown in Fig. 67A or trapezoidal as shown in Fig. 67B.

In order to prevent the antenna conductor 27 from coming out, furthermore, in addition to the arrangement of the bent portion 27b, a cutout 13p as shown in Fig. 68 may be formed in the developer housing part 13 and the antenna conductor 27 may be passed through the cutout 13p. With this arrangement, even if the antenna conductor 27 is subjected to an external force as indicated by the arrow in Fig. 68, the antenna conductor 27 does not come out of the developer housing part 13, so that the generation of a space or gap between the developer housing part and the toner leakage preventing seals 29 is prevented.

Furthermore, instead of the cutout 13p, as shown in Fig. 69, a round hole 13q having a diameter that allows the antenna conductor 27 to pass through may be formed in the developer housing part 13 and the antenna conductor 27 may be passed through the cylindrical hole 13q. Similarly to the cutout 13p, with this arrangement, even if the antenna conductor is subjected to an external force indicated by the arrow in Fig. 69, the antenna conductor 27 will not come out of the developer housing part 13.

Furthermore, although in the first embodiment the positioning of the developing cylinder 10d in its rotation direction is not As explained above, this positioning may be effected by abutting one end of the rotary shaft of the developing cylinder against a bearing member similar to the charging roller 8, and the bearing member may be cylindrical as shown in Figs. 61 to 63. Moreover, when not only the developing cylinder 10d but also non-magnetic toner is used, the toner layer on the developing cylinder 10d is formed by an applicator roller. In this case, the applicator roller may be positioned by abutting one end of a roller shaft of the applicator roller against a bearing member having the same construction as mentioned above.

(cleaning device)

Although, as shown in Figs. 12, 13A and 13B, in the above-mentioned embodiment, an example was described in which the coating plate 10i is overlapped with the toner leakage preventing seals 10h, the arrangement shown in Figs. 12, 13A and 13B may be considered based on the relationship between the cleaning means (cleaning blade 11a, drain plate 11b, toner leakage preventing seals 11e) and the photosensitive drum 7. In other words, the drain plate 11b may be overlapped with the toner leakage preventing seals 11e outside the two longitudinal ends of the cleaning blade 11a (see Fig. 24).

(Further remarks):

The process cartridge according to the present invention can be suitably applied to form not only a single-color image as mentioned above, but also a multi-color image (e.g., two-color image, three-color image or full-color image) by providing a plurality of developing devices.

Furthermore, as a development method, a conventional two-component magnetic brush development method, a cascade development method, a touch-down development method or a cloud development method can be used.

In addition, although a so-called contact charging type was adopted as the charging means in the first embodiment, a conventional charging arrangement in which three walls formed of tungsten wires are enclosed by a metal screen such as aluminum, and positive or negative ions generated by applying a high voltage to the tungsten wires are transferred to the photosensitive drum 7 to thereby uniformly charge the surface of the photosensitive drum 7 may be adopted.

The loading device may be of the blade type (loading blade type), cushion type, block type, rod type or wire type in addition to the above-mentioned roller type.

Furthermore, the cleaning device for removing the residual toner remaining on the image-bearing component, e.g. the photosensitive drum 7, can be formed by a blade, a fur brush and/or a magnetic brush.

Furthermore, regarding the image bearing member as a photosensitive body, for example, an organic semiconductor (OPC), amorphous silicon (A-Si), selenium (Se), zinc oxide (ZnO) or cadmium sulfide (CdS) may be used, and the shape of the image bearing member is not limited to the drum but may be a belt.

The process cartridge B further comprises an electrophotographic photosensitive body as an image-bearing member and at least one process functional member. Consequently, the process cartridge may integrally contain an image-bearing member and a charging device as a unit which can be detachably mounted in an image forming apparatus, or it may integrally include therein an image bearing member and a developing device as a unit which can be detachably mounted in an image forming apparatus, or it may integrally include therein an image bearing member and a cleaning device as a unit which can be detachably mounted in an image forming apparatus, or it may integrally include therein an image bearing member and two or more process function members as a unit which can be detachably mounted on an image forming apparatus such as the above.

In other words, the process cartridge integrates therein an electrophotographic photosensitive body and a charger, a developing device or a cleaning device as a unit which can be removably mounted in the image forming apparatus, or integrates therein an electrophotographic photosensitive body and at least one of a charger, a developing device and a cleaning device as a unit which can be removably mounted in an image forming apparatus, or integrates therein an electrophotographic photosensitive body and at least one of a charger, a developing device and a cleaning device as a unit which can be removably mounted in an image forming apparatus.

Furthermore, although the laser beam printer was explained as the image forming apparatus in the above-mentioned embodiments, the present invention is not limited to the laser beam printer, but can be applied to other image forming apparatuses such as an LED printer, an electrophotographic copying machine, a facsimile system or a word processor.

As mentioned above, according to this invention, since the case members constituting the case of the process cartridge are formed of the same material, the welding between the case members can be effected in a positive and strong manner.

Furthermore, since the casing parts are formed of the same material as the material of the toner, even if the casing parts to which the toner adheres are crushed, the mechanical property of the material is not deteriorated in recycling, unlike the case where different materials are mixed. Accordingly, it is not necessary to separate the casing parts independently in recycling, and the cleaning operation can be facilitated.

In addition, since the casing members are formed of a material having a charging property similar to that of the developer, even if the developer is rubbed against the casing members during the image forming process, the abnormal charging does not occur, thus obtaining a high quality image.

According to the present invention, as stated above, since the casing members for forming the casing of the process cartridge are made of the same material, the casing members can be securely and firmly welded together.

Furthermore, since the casing members are formed of the same material as that of the developer carrier, even if the casing member to which developer adheres is crushed, the mechanical property of the crushed material is not deteriorated unlike the mixture of different materials. Accordingly, in the recycling process, it is not necessary to separate the casing members from each other and it is possible to facilitate the cleaning process.

Furthermore, by forming the housing members and the developer from materials having the same charging property, even if the developer is rubbed against the housing member during the developing process, there is no fear of the charging abnormality occurring, so that the image of high quality is obtained.

Claims (14)

1. An electrophotographic process cartridge comprising: a housing containing a container (10a) for a developer, a rotatable photosensitive drum (7), a driven gear (7c) coaxial with the drum, and charging, developing and cleaning means (8, 10, 11) cooperating with the drum, the housing having a first opening for the passage of light to the drum to form a latent image thereon and a second opening for transferring developed images from the drum to a transfer material, the cartridge being adapted to be removably inserted in a direction transverse to the axis of the drum into an image forming apparatus having an arrangement (17, 18) for guiding the cartridge to an operative position in the apparatus and supporting the cartridge in the operative position, the driven gear being operative with the drive gear of the apparatus in the meshing engagement, the drum being mounted in the housing at its front portion with respect to the direction of insertion, outwardly projecting guide means (21, 40, 43) being arranged on the housing on opposite sides of the front portion to cooperate with the arrangement for effecting the guiding of the cartridge, and a rear portion (12d; 73; 74) of the housing with respect to the direction of insertion being constructed such that it can be gripped by an operator to insert and remove the cartridge from the device; wherein the housing has a front, middle and rear housing frame (14, 13, 12), wherein the rear housing frame (12) forms the developer container (10a), the middle housing frame forms a frame for the developing device (10) and the front Housing frame forms a frame for the photosensitive drum (7) and contains a container (llc) for used toner which is remote from the photosensitive drum; wherein the front, middle and rear housing frames are formed of the same synthetic resin material; and wherein the used toner container (llc) comprises inner ribs (14q, 14r in Fig. 60) for reinforcing the front housing frame. 2. Cartridge according to claim 1, wherein the synthetic resin material of the case frame is polystyrene resin. 3. Cartridge according to claim 1 or 2, wherein the developer container contains developer material. 4. A cartridge according to claim 3, wherein the developer material and the material of the housing frames are so close to each other in the triboelectric sequences that no abnormal charging occurs when the developer material rubs against the housing frame. 5. Cartridge according to claim 3 or 4, wherein the developer material comprises magnetic particles with a binding material of styrene-acrylic resin. 6. Cartridge according to one of the preceding claims, wherein the rear and middle housing frames are ultrasonically welded together. 7. A cartridge according to any preceding claim, wherein the front and middle housing frames are connected together for tilting movement with respect to each other. 8. A cartridge according to any preceding claim, wherein the front housing frame has a pair of side wall portions (14p) supporting the drum and an upper wall portion (14n) extending between the side wall portions above the drum. 9. A cartridge according to any preceding claim, wherein the inner ribs comprise partition wall portions (14q) dividing the used toner container into a plurality of chambers and additional ribs (14r) reinforcing each chamber. 10. A combination of an electrophotographic image forming apparatus and a cartridge according to any one of the preceding claims. 11. A combination according to claim 10, wherein the device is in the form of a copier, a laser beam printer, an LED printer, a facsimile receiver or a word processor. 12. A method for producing process cartridges, comprising the following steps: Disassembling a plurality of used cartridges according to any one of claims 1 to 9 into component parts; Cleaning at least some of the component parts; and Assembling process cartridges using at least some of the cleaned parts. 13. The method of claim 12, further comprising the step of selecting some of the component parts for direct reuse, the parts being cleaned in the cleaning step. 14. A method according to claim 12 or 13, further comprising the steps of selecting some of the component parts for indirect reuse and breaking and recasting those component parts.