JP2000227707A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device constituted so that visible image processing is prevented from being interrupted by precisely deriving a developing unit whose residual quantity of developer is reduced. SOLUTION: A developing device 5 used for the visual image processing of a latent image formed on a latent image carrier 2 by an electrophotographic system is equipped with the plural developing units 5Y so that the residual quantity of developer in the units 5Y is detected. Besides, the developing device 5 is provided with a driving source (motor) for successively making the units 5Y face the carrier 2. By the driving source, the units 5Y are moved every time that an image is formed on the prescribed number of sheets regardless of an image forming mode so as to make the unit 5Y being the object whose residual quantity of developer is detected face the carrier 2 by being different from that before it is moved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a developing apparatus for processing an electrostatic latent image formed on a latent image carrier by an electrophotographic method into a visible image. The present invention relates to a structure for detecting a remaining amount of a developer in a developing unit.

[0002]

2. Description of the Related Art In general, an image forming apparatus using an electrophotographic method, such as a copying machine or a printer, uses a photosensitive member constituting a latent image carrier. In electrophotography,
After the photoreceptor is uniformly charged, light is written using laser light or the like, a latent image corresponding to the original is formed, the latent image is processed with a developer, and then the visible image is transferred. An image is obtained by transferring the image to paper or the like.

In recent years, color image forming apparatuses for forming images of not only a single color but also a plurality of colors including a full color have been proposed and put into practical use. In a color image forming apparatus, a latent image is formed on a photoreceptor by reflected light obtained by performing color separation of reflected light from a document, and in a printer, irradiation images corresponding to color information form latent images. The visible image is processed with a developer of a color that is complementary to the color-separated reflected light or irradiation light, and the process of primary transferring the visible image to the intermediate transfer member is repeated. The corresponding visible images are collectively transferred to a transfer paper or the like by a secondary transfer process.

As one of the structures of a developing device used for visible image processing in a color image forming apparatus, a developing unit containing developers of different colors at regular intervals along a circumferential direction of a rotating body is arranged. There is a configuration in which each developing unit faces the photoconductor by intermittently rotating the rotator to perform visible image processing of a latent image by using developers of different colors.

The developing unit may use a one-component developer composed of only a magnetic or non-magnetic toner. In this case, the developing unit is carried on a developing sleeve arranged opposite to the photosensitive member. The one-component developer is thinned and supported by a blade or the like.

In a developing device provided in a color image forming apparatus, an image is formed by supplying a developer with one of developing units arranged side by side in a circumferential direction facing a photoreceptor. When image formation is not performed, that is, during non-image formation, the developing unit is not opposed to the photoconductor, thereby preventing the photoconductor from being stained. For this reason, the developing device is maintained in a standby state in which the developing unit does not face the photoconductor until image formation is restarted during non-image formation.

[0007]

SUMMARY OF THE INVENTION
When the contained developer is consumed and becomes less than a predetermined amount, an abnormal image is generated due to insufficient image density or the like. Therefore, it is necessary to monitor the remaining amount of the developer in the developing unit. There is a configuration in which the remaining amount of the developer in the developing unit is disposed in the vicinity of the developing device, for example, by using an optical detection unit to determine the presence or absence of the developer based on the light transmission state. When the developer remaining amount detection is performed for the configuration in which the developing units are arranged side by side in the circumferential direction, among the developing units sequentially rotating in the circumferential direction, the developing unit located at the lowest position detects the developer remaining amount. Be eligible. This is because the developer in the developing unit located at the lowermost position is easily concentrated at a predetermined location by gravity, that is, at the lower part in the developing unit. This is because it can be determined that most of the agent is at a position corresponding to the optical detection means.

However, when the remaining amount of the developer is detected for the developing unit located at the lowest position, there are the following problems. In a developing device, visible image processing may be continuously performed using a developer of a specific color. When the developing unit continues to face the photoconductor, the developing unit positioned at the lowest position is targeted. The remaining amount of the developer may be detected. For this reason, despite the fact that there is a developing unit in which the remaining amount of the developer is smaller than the lowest developing unit due to continuous consumption, the remaining amount of the developer is not more than the predetermined amount. It is not possible to accurately determine the developing unit in which the developing unit is performing continuous visible image processing.

SUMMARY OF THE INVENTION In view of the above-described problems relating to the conventional image forming apparatus, particularly the problem of detecting the remaining amount of developer in a developing unit, the present invention is directed to accurately determining a developing unit having a small remaining amount of developer. An object of the present invention is to provide an image forming apparatus having a configuration capable of preventing image processing from being interrupted.

[0010]

According to the first aspect of the present invention,
A developing device used for visible image processing of a latent image formed on a latent image carrier by an electrophotographic method is provided with a plurality of developing units and configured to detect a remaining amount of the developer in the developing unit. In the image forming apparatus, the developing device includes a driving source for sequentially causing the developing unit to face the latent image carrier, and the driving source is configured to perform a predetermined number of image forming operations regardless of an image forming mode. Then, the developing unit is moved so that the developing unit to be subjected to the remaining amount detection of the developer is made different from that before the movement to correspond.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the developing device is a rotary type developing device in which the developing units are arranged side by side in a circumferential direction. The present invention is characterized in that a developing unit different from that before the rotation is opposed to the configuration in which the developing unit is rotated to detect the remaining amount of the developer every time an image is formed.

The invention described in claim 3 is the first or second invention.
In the image forming apparatus described above, the rotation of the driving source is controlled by a control unit, and the control unit is configured such that an image formation number detection unit for detecting the number of image formation and a developer remaining amount detection unit are connected to an input side, and an output is provided. The drive source is connected to the side, and after a predetermined number of image formations are completed by the image formation number detection means, the drive source is driven to terminate the predetermined number of image formations with respect to the developer remaining amount detection means. The remaining amount of the developer is detected by the developer remaining amount detecting means by positioning a different developing unit.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the developer remaining amount detecting means is a space where a developer is interposed on an inner surface of a developer replenishing member provided in the developing unit. And a pair of light transmitting means arranged and arranged outside the developing unit so as to face the light transmitting means and emit and receive the remaining amount detection light to the light transmitting means. And an optical sensor.

According to a fifth aspect of the present invention, in the image forming apparatus of the fourth aspect, the optical sensor is located at a position where a state in which the developer in the developing replenishing means is accumulated downward by gravity is obtained. The light transmission means in the unit is arranged as a target.

According to a sixth aspect of the present invention, in the image forming apparatus of the fourth aspect, a cleaning member that can move forward and backward is disposed between the opposing surfaces of the light transmitting means,
When entering between the opposing surfaces, a configuration is provided for cleaning the opposing surfaces, respectively.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a main configuration of a color image forming apparatus which is one of the image forming apparatuses according to the present embodiment. In FIG. 1, a color image forming apparatus 1
Is provided with a photoreceptor 2 as a latent image carrier in a housing. The photoreceptor 2 is formed in a belt shape (hereinafter, referred to as a photoreceptor belt) wrapped around a pair of pulleys 2A and 2B, and moves in the direction indicated by the arrow as each pulley 2A and 2B rotates clockwise as indicated by the arrow. I do. In FIG. 2, a roller 2C disposed inside the photosensitive belt 2 is a tension roller.

Around the photoreceptor belt 2, a charging device 3, an optical writing device 4, a developing device 5, a transfer device 6, and a cleaning device 7 for performing electrophotography along the moving direction are arranged. I have. The developing device 5
Has a configuration in which developing units accommodating developers for a plurality of colors are arranged along the circumferential direction, as will be described later. The agent is supplied. Transfer device 6
Is a transfer belt 6 which is wound around a pair of rollers 6A and 6B and moves in the same direction at a position facing the photoreceptor belt 2.
C, and a bias device 6D for setting a transfer bias is disposed at a position facing the photoreceptor belt 2. In FIG. 1, reference numeral 6E denotes a cleaning device for removing the developer remaining on the transfer belt 6C in the transfer device 6.

In the vicinity of the transfer device 6, the collective transfer device 9 is disposed on the roller 6A side in such a manner as to face a surface of the transfer belt 6C opposite to the surface facing the photoreceptor belt 2 among the expanded surfaces of the transfer belt 6C.
Is arranged.

The batch transfer device 9 is constituted by a bias device that batch-transfers a full-color image superimposedly transferred onto the transfer belt 6C onto a recording medium such as a transfer sheet fed from the sheet feeding device 8.

The paper feeding device 8 includes a paper feeding cassette 8A for accommodating a recording medium such as transfer paper, a feeding roller 8B for feeding out the recording medium from the paper feeding cassette 8A, a conveying roller 8B1, and a registration roller 8B2. Have. In this embodiment, a part of the housing of the color image forming apparatus 1 (for convenience, indicated by reference numeral 1A) is provided as an openable and closable cover, and a manual paper feed tray 1B is provided therein. A conveyance path switching claw 8B3 for setting a conveyance path between the recording medium from the sheet feeding tray 8A and the recording medium from the manual sheet feeding tray 1B is provided in front of the registration roller 8B2. The route can be switched to be guided to the collective transfer device 9.

A fixing device 10 for fixing an image transferred on a recording medium is provided behind the collective transfer device 9. The fixing device 10 includes a heating roller 10A having a built-in heater and a heating roller 10A. A pressure roller 10 </ b> B is provided in contact with and in opposition to the pressure roller 10 </ b> B.

The recording medium fixed by the fixing device 10 is discharged onto a discharge tray 12 by a discharge roller 11. In FIG. 1, reference numeral 10C denotes
Fig. 3 shows an oil application device for preventing transfer of a developer.

In the color image forming apparatus using the photoreceptor belt 2, when the electrostatic latent images of each color are processed into a visible image by the developing device 5, the visible images are sequentially transferred to the transfer belt 6 C of the transfer device 6. A full-color image is formed by superimposed transfer, and the full-color image is collectively transferred to a recording medium.

The developing device 5 includes four developing units containing yellow, magenta, cyan, and black developers having a complementary color relationship with the color separated along the circumferential direction. The unit constitutes a rotary developing device capable of supplying a developer of a color corresponding to an electrostatic latent image formed on the photosensitive belt 2 opposite the photosensitive belt 2. The developing units included in the rotary developing device 5 have the same configuration, and details thereof are shown in FIG. FIG. 2 shows a state in which one of the developing units faces the photoreceptor belt 2 to perform visible image processing. In FIG. 2, the developing unit (for convenience, a developing unit containing a yellow developer is shown). 5Y has a configuration using a non-magnetic one-component developer. That is, the developing unit 5Y is provided with the developing sleeve 5Y1 whose part of the peripheral surface is exposed from the opening formed in part of the casing. The rotation direction of the developing sleeve 5Y1 is set such that the developing sleeve 5Y1 moves in the same direction at a position facing the photosensitive belt 2 at a predetermined peripheral speed ratio. A supply roller 5Y2 for supplying the developer is in contact with the developing sleeve 5Y1.
The supply roller 5Y2 is a roller made of an elastic body such as foamed polyurethane, and has a rotation direction in which the supply roller 5Y2 moves in the same direction at the contact position with a predetermined peripheral speed ratio with the developing sleeve 5Y1.

A housing space 5Y3 for housing the developer is provided in a part of the developing unit 5Y.
Between the supply roller 5Y2 and the supply roller 5Y2,
A flicker member 5Y4 that is pressed against the peripheral surface with a predetermined bite amount and a shielding member 5Y5 that is disposed between the flicker member 5Y4 and the housing space 5Y3 are provided. The flicker member 5Y4 frictionally charges the developer from the storage space 5Y3 while being carried on the surface of the supply roller 5Y2, and supplies the developer with the supply roller 5Y3.
2 is a member that regulates the amount of developer carried, and is configured to rotate in a rotation direction that moves in the same direction at a pressure contact position with the supply roller 5Y2.

The shielding member 5Y5 is a blade member for preventing the developer from flowing directly from the storage space 5Y3 toward the developing sleeve 5Y1, and the developer in the storage space 5Y3 is supplied between the supply roller 5Y2 and the flicker member 5Y4. Only to be introduced. For this reason, the flicker member 5Y4
The developer is carried on the developing sleeve 5Y1 in a state where the shortage of the charge amount generated in the developer reaching the developing sleeve 5Y1 without passing through the developing sleeve 5Y1 is eliminated.

The developer in the accommodating space 5Y3 reduces the bulk density between the particles due to air entering between the particles due to the inertia when the rotary developing device 5 rotates, so-called adhesive force between the particles. Has the property of increasing the fluidity by being weakened, exhibits fluidity like a liquid, and can flow out of the storage space 5Y3. For this reason, as shown in FIG. 2, when the opening of the storage space 5Y3 faces downward, that is, when the shielding member 5Y5 is located below the storage space 5Y3, the shielding member 5Y5 directs the toner to the developing sleeve 5Y1. Flow is regulated, and the developer flowing out of the storage space 5Y3 is pumped up by the rotation direction of the supply roller 5Y2. The amount of the developer drawn up by the supply roller 5Y2 is regulated by the cooperation of the supply roller 5Y2 and the flicker member 5Y4, and the required charge amount when the developer is carried on the development sleeve 5Y1 is friction. Set by charging.

The developing unit 5Y includes a developing sleeve 5Y.
A thinning blade 5Y6 is provided in contact with the peripheral surface at a position before facing the photoreceptor belt 2 in one rotation direction. The thinning blade 5Y6 is a member for regulating the developer carried on the developing sleeve 5Y1 into a thin layer having a uniform thickness, and is a thin plate having a spring property such as a stainless steel plate or an elastic material such as urethane rubber. Are supported in a cantilever shape.

In the developing unit 5Y, when the developing sleeve 5Y1 is disposed at a position facing the photoreceptor belt 2 by the rotation of the developing device 5, the developer flows out of the accommodating space 5Y3 and flickers when it is pumped up by the supply roller 5Y2. The amount of toner carried on the supply roller 5Y2 is regulated by the member 5Y4, and is supplied to the developing sleeve 5Y1 after being triboelectrically charged. The developer carried on the developing sleeve 5Y1 is defined as a thin layer having a uniform thickness by the thinning blade 5Y6, and is supplied to the electrostatic latent image on the photosensitive belt 2 by contact or non-contact.

Each of the developing sleeves including the developing sleeve 5Y1 is mounted on a rotatable developing unit supporting member 5F provided in the image forming apparatus, as shown in FIG. The developing unit supporting member 5F has a length that can accommodate the developing unit, has an end plate 5F2 having an opening 5F1 into which each developing unit can be inserted, at one end in the longitudinal direction, and a motor (not shown) serving as a rotational drive source. Gear 5G, which is a power transmission mechanism, is provided at the other end in the longitudinal direction. The end plate 5F2 and the gear 5G are arranged along the direction in which the developing units are juxtaposed, and are connected to each longitudinal end of a partition wall 5F3 that partitions the mounting portion of each developer unit. Although FIG. 3 shows only a developing unit for yellow developer denoted by reference numeral 5Y, each of the cyan, magenta, and black developing units (not shown) is a developing unit support member similarly to the developing unit 5Y. 5F can be inserted and removed through the opening 5F1.

The developing unit supporting member 5F is driven by a motor (not shown) as a driving source for transmitting a driving force to the gear 5G. Are driven to rotate in a state in which they do not face the photosensitive belt 2 and in a state in which the developing sleeve faces the photosensitive belt 2. FIG. 4 shows the arrangement of each developing unit at the home position of the developing device 5. In FIG. 4, in the rotating direction of the developing device 5 (the direction of the arrow in the drawing), the developing unit 5Y containing the yellow developer performs image formation. Sometimes, the positional relationship between the developing units is determined so as to face the photoreceptor belt 2 first. Therefore, when the developing device 5 is set at the home position, the developing sleeve 5Y1 of the developing unit 5Y containing the yellow developer and the developing unit 5Y in the rotation direction of the developing device 5 are located at the rearmost position. The intermediate position of the developing unit 5B containing the black developer and the developing sleeve 5B1 faces the photoreceptor belt 2.

At the time of image formation, the developing unit (developing unit indicated by reference numeral 5Y) is moved from the home position shown in FIG. 4 so that the developing sleeve in the developing unit faces the photosensitive belt 2 as shown in FIG. Be tilted.

In FIGS. 3 and 4, reference numerals 5YT, 5C
The members denoted by T, 5MT, and 5BT indicate developer replenishment tanks that communicate with the storage spaces 5Y3, 5C3, 5M3, and 5B3 of each of the developing units. The developer replenishment tanks (represented by reference numeral 5YT for convenience) Use)
As shown in FIG. 3, is connected to one end in the longitudinal direction of the developing unit 5Y. Although FIG. 3 shows only the developing unit 5Y containing the yellow developer, other developing units are similarly provided with a developer replenishing tank. Developer replenishment tank 5Y
In T, 5CT, 5MT, and 5BT, a developer storage space 5 is provided.
Y3, 5C3, 5M3, and 5B3 are provided to take in the developer in conjunction with the rotation of the developing unit. FIG. 6 shows a process of rotating the developing unit for image formation from a state where the developing device 5 is located at the home position. The internal structure of the developer replenishing tank in FIG. is there. In FIG. 6, the description will be made with reference to the developer replenishment tank indicated by reference numeral 5YT, but the other developer replenishment tanks have the same configuration. FIG. 6A shows a state in which the developing device 5 is located at the home position. In FIG. 6A, a weir extending from a part of the wall of the storage space 5Y3 is provided inside the developer replenishing tank 5YT. A plate 5YT1 is provided. The weir plate 5YT1 has a funnel-shaped wall that converges toward the accommodation space 5Y3. When the developing device 5 is located at the home position, the upper part of the space 5YT2 which is blocked by the weir plate 5YT1 and communicates with the housing space 5Y3 is opened, so that the developer accumulated in the space 5YT2 is removed. It flows into the storage space 5Y3 due to its own fluidity.

When the developing unit 5Y is rotated from the home position to face the photosensitive belt 2, FIG.
As shown in (B), the developer received by the weir plate 5YT1 does not flow down due to the inclination of the weir plate 5YT1 and can flow into the storage space 5Y3 by the action of gravity. The developer spilled from 5YT1 accumulates on the inner surface of the lower peripheral wall of the developer replenishing tank 5YT. When the developing unit 5Y is located at the lowest position,
As shown in FIG. 6C, most of the spilled developer accumulates on the inner surface of the lower peripheral wall of the developer replenishing tank 5YT, and when the developer rotates upward from the lowest position, the development is performed by the weir plate 5YT1 as shown in FIG. The agent is pumped up to the state shown in FIG.

The inside of the developer replenishing tanks 5YT, 5CT, 5MT and 5BT having a structure capable of flowing the developer contained therein into the containing space is provided for detecting the remaining amount of the developer. A configuration is provided. FIGS. 5, 7, and 8 are diagrams showing a configuration for detecting the remaining amount of the developer. In FIG. 5, the configuration for detecting the remaining amount is the developer replenishment tanks 5YT, 5CT, 5MT,
Light transmitting means 20Y, 20 provided inside 5BT
C, 20M, 20B and developer replenishment tanks 5YT, 5C
And an optical sensor 21 disposed outside the rotation trajectory of the T, 5MT, and 5BT.

Light transmitting means 20Y, 20C, 20M, 20
B, as shown in FIG. 7, is constituted by a pair of pentaprisms provided at spaced positions to form a space (for convenience, denoted by reference numeral S) in which the developer is interposed (in FIG. 7, Reference numeral 20Y is used for convenience).

The base of the light transmitting means 20Y is a window 5YT3 formed on the peripheral wall of the developer replenishing tank 5YT (see FIG. 8).
And are positioned and mounted opposite to each other.

The optical sensor 21 is, as shown in FIG. 5, a developing unit located at the lowest position where the developer can be gathered downward by gravity. In FIG. 5, the developing unit 5B
And a light emitting unit 21A that emits detection light toward one of the light transmitting units 20Y and a light transmitting unit 20Y, as shown in FIG. 7A. A light receiving unit 21B for receiving light from the other side.

As shown in FIG. 7, the light transmitting means 20Y can detect the remaining amount of the developer according to the state of light transmission in the space S where the developer intervenes.
As shown in (A), when light from the light emitting unit 21A of the optical sensor 21 is received by the light receiving unit 21B via the light transmitting unit 20Y, it means that the remaining amount of the developer is equal to or less than a predetermined amount. The detection signal is output to the control unit 22 described later. As shown in FIG. 7B, when light cannot be transmitted between the light transmitting means 20A, the developer is present in the space S. In this case, the optical sensor 2
No signal is output from 1 to the control unit 22.

The control unit 22 controls the rotation of the developing unit supporting member 5F as well as a function of notifying the user of the result of detecting the remaining amount of the developer. FIG.
FIG. 3 is a block diagram for explaining a configuration of the control unit 22. In the figure, a main part of a control unit 22 is constituted by a microcomputer, and an I / O (not shown)
An image forming number detecting unit 23 and an optical sensor 2 as a developer remaining amount detecting unit on an input side via an O interface
1 is connected to the output side, and a motor 24, which is a drive source for rotationally driving the gear 5G of the developing unit support member 5F, is connected via a drive unit (not shown).

As the image formation number detecting means 23, a resettable counter capable of counting the number of image formation is used in addition to a counter for counting the number of recordings designated by the user.

The control unit 22 includes an image forming number detecting unit 23.
When the number of times of image formation counted by
Irrespective of the image forming mode, a developing unit different from the developing unit which has been positioned at the lowest position is moved to the lowest position so that the light transmitting means in the developer replenishment tank and the optical sensor 21 are opposed to each other. In other words, when a full-color image is formed, since each developing unit rotates sequentially, when the developer replenishment tank of the developing unit is positioned at the lowest position during the rotation, the optical sensor 21 detects the remaining amount of the developer, If no developer remains in the developer replenishment tank located at the lowest position, a warning process for insufficient remaining amount is performed at that time. When the number of image formations reaches a predetermined number during image formation, each developing unit is forcibly rotated at the time when the image formation is completed at that time, and is replaced with the developing unit located at the lowest position. Locate different developing units. In particular, it is intended that when the predetermined number is reached, the developing unit still facing the photoreceptor belt 2 is forcibly rotated and moved to the lowest position. In other words, when the visible image processing is continuously performed by the same developing unit, when the developing unit is forcibly moved to the lowest position when the number of image formation reaches a predetermined number, the developing The remaining amount is detected by the light transmitting means and the optical sensor 21 in the developer replenishing tank of the unit.

Since the present embodiment has the above configuration,
The operation will be described with reference to a flowchart illustrating the operation of the control unit 22, as shown in FIG. In FIG. 10, when image formation is being performed, the developing unit in the lowest developing unit is positioned by the developer replenishment tank of the lowest developing unit facing the optical sensor 21 during the rotation of each developing unit. The remaining amount of the developer in the developer supply tank is detected. That is, as shown in FIG.
The remaining amount of the developer is detected based on the light transmission state corresponding to the amount of the developer in the space S located between the opposing surfaces of the light transmitting means 20Y, 20C, 20M, and 20B, and whether the remaining amount is insufficient is determined. Is determined (ST1). In the determination in this case,
The presence or absence of a signal from the optical sensor 21 is determined, and when the signal from the optical sensor 21 is output, it is determined that the remaining amount is insufficient and a warning is issued (ST2).

On the other hand, if the remaining amount is not insufficient in the determination in step ST2, the number of image formations is determined (S2).
T3). When the number of image formations reaches a predetermined number (N), even if the number of image formations specified by the user is in the middle,
When the visible image processing is completed by the developing unit facing the photoreceptor belt 2, the developing unit is forcibly rotated (ST4). The rotation amount in this case is at least a rotation amount capable of moving the developing unit facing the photoreceptor belt 2 to the lowest position when the predetermined number is reached. Light transmitting means in the replenishment tank (reference numerals 20Y, 20C,
20M or 20B) and the optical sensor 21 can detect the remaining amount.

In the case where the latent image on the photosensitive belt 2 is continuously processed by the developing unit facing the photosensitive belt 2 when the predetermined number of image formations is completed, In some cases, the remaining amount of the developer in the developing unit may be smaller than the remaining amount of the developer in the developing unit that was previously at the lowest position. Instead of the developing unit, the developing unit facing the photoreceptor belt 2 at the end of the predetermined number of image formations moves to the lowest position. This makes it possible to identify a developing unit whose remaining amount of the developer is low.

The remaining amount of the developer in the developing unit moved to the lowest position by driving the motor 24 in step ST4 is detected (ST5), and a warning is issued if the developer is insufficient (ST2).

If there is no shortage of developer in step ST5, the number of image formations corresponding to the predetermined number of times that is the reference for the processing in step ST4 is reset (ST5).
6). The reset in this case is not the reset of the number of image formations designated by the user, but the number of image formations previously set in the control unit 22 as a reference for forcibly driving the motor 24 regardless of the image formation mode, that is, , The number of image forming processes to be repeatedly performed is initialized (“0”).
To). Therefore, not only when the predetermined number is reached within the specified number of image formations, but also when the predetermined number of images is not reached within the specified number of image formations, the designation at the time of the next image formation is executed. If the number reaches the predetermined number including the number, the process shown in step ST4 is executed.

In this embodiment, a structure for improving the accuracy of the detection of the remaining amount of the developer is provided. That is, as shown in FIG. 5 and FIG.
0, this means is shown in FIG.
C, 20M, and 20B) are provided with cleaning means 25 that can advance and retreat into the space S located between the opposing surfaces. The cleaning means 25 is a swinging member whose base is pivotally supported by a stationary member 26 provided on the peripheral wall of the developer replenishing tank, as shown in FIG. 11A, and as shown in FIG. A weight 25A and a cleaning member 25B are provided at the base. An elastic body such as urethane foam is used for the cleaning member 25B,
By moving in the space S, the opposing surface of the light transmitting means 20 can be contacted and wiped.

The cleaning means 25 utilizes the fact that the weight 25A swings according to gravity, as shown in FIG.
The cleaning member 25 </ b> B at the base enters the space S to clean the opposing surface of the light transmitting unit 20. That is, in FIG. 5, in the developing units 5Y and 5C, the cleaning member 25B at the base enters the space S by hanging down or swinging counterclockwise due to the rotational moment generated in the weight 25A, and the developing unit 5
In M and 5B, the cleaning member 25B at the base retreats from the space S by hanging down or swinging counterclockwise due to the rotational moment. As a result, the facing surface of the light transmitting means 20 is cleaned when the developing device 5 rotates,
The developer adhering to the opposing surface can be removed to optimize the light transmission state.

[0051]

According to the first to third aspects of the present invention, since the developing unit provided in the developing device is rotated and moved every time a predetermined number of images are formed, the developing unit opposed to the developer remaining amount detecting means is provided. Is changed every time a predetermined number of images are formed. As a result, the developing unit containing the continuously consumed developer is also detected as the unit for detecting the remaining amount of the developer every time a predetermined number of images are formed. It is possible to accurately detect the remaining amount even when performing visible image processing. As a result, even when the developing unit in which the amount of the developer is most remarkably reduced is used for the visible image processing, the remaining amount of the developer in the developing unit can be detected. Therefore, it is possible to prevent the image formation from being interrupted when the developing unit is not replaced.

According to the inventions described in claims 4 to 6, as a configuration for detecting the remaining amount of the developer, the developer is separated by a gravity between the light transmitting means provided on the developing sleeve side and each of the developing sleeves. By using an optical sensor arranged for the developing sleeve at a position where a state where it can accumulate below can be obtained, there is no need to provide an optical sensor for each developing sleeve, and the remaining amount of developer can be accurately measured with a simple configuration. Can be detected. In particular, since the opposing surfaces of the light transmitting means are cleaned, it is possible to prevent the developer from adhering to the opposing surfaces and to accurately detect the remaining amount. As a result, it is possible to accurately determine the developing unit in which the remaining amount of the developer is insufficient.
It is possible to prevent image formation from being interrupted when the remaining amount of the developing unit is not detected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a main part of an image forming apparatus according to an example for describing an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a configuration of a developing unit provided in a developing device used in the image forming apparatus shown in FIG.

FIG. 3 is a perspective view of a main part for describing a support structure of a developing unit used in the image forming apparatus shown in FIG.

FIG. 4 is a schematic side view illustrating one embodiment of a developing unit supported by the support structure shown in FIG. 3;

FIG. 5 is a schematic side view for explaining another embodiment of the developing unit supported by the support structure shown in FIG. 3;

6 is a view for explaining an internal structure of a developer replenishment tank attached to the developing unit shown in FIG. 3,
(A) shows a special state in which the developing device is at the home position, and (B) to (D) show states in which the developer carrier successively faces the latent image carrier.

FIGS. 7A and 7B are schematic diagrams for explaining a configuration for detecting a remaining amount of a developer in the developing unit shown in FIG. 2, wherein FIG. Each state shows that the agent is not short.

FIG. 8 is a perspective view showing a developing unit provided with the detection configuration shown in FIG. 7;

9 is a block diagram for explaining a configuration of a control unit used for controlling the rotation of the developing unit shown in FIG.

FIG. 10 is a flowchart for explaining the operation of the control unit shown in FIG. 9;

11 is a perspective view for explaining a cleaning structure used in the configuration for detecting the remaining amount of the developer shown in FIG. 7;
(A) shows one embodiment, and (B) shows another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Color image forming apparatus which is one of image forming apparatuses 1C Side wall 1D Opening 1D1 Lower side 1D2 Vertical side 1D3 Curved side 2 Photoconductor belt which is a latent image carrier 3 Charging device 4 Optical writing device 5 Developing device 5Y, 5C, 5M, 5B Developing unit 5Y1, 5C1, 5M1, 5B1 Developing sleeve 5YT, 5CT, 5MT, 5BT Developer replenishing tank 5F Developing unit support member 20Y, 20C, 20M, 20B Light transmitting means 21 Optical sensor 22 Control unit 23 Image forming number Detection means 24 Motor as drive source 25 Cleaning means 25A Weight 25B Cleaning member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA41 DD02 DE02 DE07 DE09 DE10 EA04 EB04 2H077 AC04 AD02 AD06 AD13 AD18 AE02 BA01 BA09 BA10 DA15 DA22 DA35 DA64 DA83 DA93 DB02 DB10 DB15 EA11 GA13

Claims (6)

[Claims] A developing device used for visible image processing of a latent image formed on a latent image carrier by an electrophotographic method is provided with a plurality of developing units, and a developer remaining amount in the developing unit is detected. An image forming apparatus having a configuration in which the developing unit is provided with a driving source for sequentially causing the developing unit to face the latent image carrier, wherein the driving source is a predetermined driving source regardless of an image forming mode. An image forming apparatus, wherein the developing unit is moved every time image formation is performed, and a developing unit to be a developer remaining amount detection target is made different from that before the movement to correspond to the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein said developing device is a rotary developing device in which said developing units are juxtaposed in a circumferential direction, and said rotary drive source is provided for each predetermined number of image formations. An image forming apparatus characterized in that a developing unit different from that before rotation is opposed to a configuration in which the developing unit is rotated to detect the remaining amount of the developer. 3. An image forming apparatus according to claim 1, wherein said drive source is rotationally controlled by a control unit, said control unit comprising: an image formation number detecting means for detecting the number of image formation; Means is connected to the input side, and the drive source is connected to the output side. After a predetermined number of image formations are completed by the image formation number detection means, the drive source is driven to drive the developer remaining amount detection means to the developer remaining amount detection means. On the other hand, an image forming apparatus characterized in that a developing unit different from the end of the predetermined number of image formations is positioned and the remaining amount of the developer is detected by the developer remaining amount detecting means. 4. The image forming apparatus according to claim 3, wherein said developer remaining amount detecting means is arranged with a space interposed between a developer and an inner surface of a developer replenishing member provided in said developing unit. A pair of light transmitting means, and disposed opposite the light transmitting means outside the developing unit,
An image forming apparatus, comprising: an optical sensor capable of emitting and receiving remaining amount detection light to and from the light transmitting means. 5. An image forming apparatus according to claim 4, wherein said optical sensor is arranged so that said light transmitting means in said developing unit is positioned at a position where said developer in said developing replenishing means can accumulate downward by gravity. An image forming apparatus characterized in that the image forming apparatus is arranged for an object. 6. The image forming apparatus according to claim 4, wherein a cleaning member which can move forward and backward between the opposing surfaces of the light transmitting means is disposed between the opposing surfaces. An image forming apparatus is provided with a structure for cleaning the opposing surfaces.