JP4348935B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming technique such as a printer, a copying machine, and a facsimile machine, and more particularly to an image forming technique that employs wet development as a developing method.
[0002]
[Prior art]
Conventionally, a charged photosensitive member is exposed by an exposure unit to form an electrostatic latent image on the photosensitive member, and toner is attached to the photosensitive member by a developing unit to visualize the electrostatic latent image to form a toner image. An electrophotographic image forming apparatus that has been formed and transferred a toner image onto a transfer sheet to obtain a predetermined image has been put into practical use. Here, as a developing method of the developing means, a wet developing method using a developer in which toner is dispersed in a liquid carrier is known. This wet development system has the advantages that the average particle diameter of the toner is as small as 0.1 to 2 μm, so that a high-resolution image can be obtained, and a uniform image can be obtained because of the high fluidity of the liquid. ing. In an image forming apparatus employing such a wet development method, cleaning is performed to remove a developer remaining on the surface of an image carrier (photosensitive body or intermediate transfer medium) after transfer by a cleaning device (for example, Patent Documents). 1). This apparatus includes a cleaning roller in which a cleaning surface having a recess moves with respect to the surface of the image carrier, and cleans residual developer on the image carrier using contact pressure between the cleaning surface and the image carrier. It is.
[0003]
[Patent Document 1]
JP 2002-6709 A (paragraph [0036], FIG. 4)
[0004]
[Problems to be solved by the invention]
By the way, in the apparatus described in the above-mentioned conventional patent document 1, when a configuration is adopted in which the cleaning roller is pressed against the image carrier with a constant pressure in order to ensure the contact pressure between the cleaning roller and the image carrier. In other words, once the cleaning roller is deformed due to deterioration with the passage of time, the deformation further proceeds. When the cleaning roller is deformed, the nip width formed by the cleaning roller and the image carrier changes. When the nip width increases, the cleaning roller and the image carrier are worn, so that it is impossible to ensure good durability. On the other hand, when the nip width decreases, the cleaning performance deteriorates.
[0005]
The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus and method that can ensure good durability and prevent deterioration in cleaning performance.
[0010]
[Means for Solving the Problems]
To achieve the above SL is provided an image forming apparatus according to the present invention is to carry an electrostatic latent image on the surface, the first conveying while carrying the toner image the electrostatic latent image is visualized The toner image is formed by supplying a latent image carrier that can be conveyed in a direction and a developer having a toner concentration of about 5 to 40% by weight dispersed in a liquid carrier to the latent image carrier. Developing means, an intermediate transfer medium that can be conveyed in the second conveyance direction while carrying a toner image, and a toner image on the latent image carrier are primarily transferred to the intermediate transfer medium at a predetermined primary transfer position. A primary transfer means and a toner image transported in the second transport direction from the primary transfer position on the intermediate transfer medium toward the predetermined secondary transfer position to the recording medium at the secondary transfer position. Secondary transfer means for transferring and the primary transfer position Serial on the latent image bearing member at a downstream side of the first conveying direction, the peripheral surface thereof is fixed so as to abut, and is provided rotatable about a rotation axis about perpendicular to the first conveying direction, the circumferential surface A latent image carrier cleaning roller having a coating layer formed of a synthetic resin or a synthetic rubber, and a peripheral surface of the intermediate transfer medium that is in contact with the intermediate transfer medium downstream of the secondary transfer position in the second transport direction. A cleaning roller for an intermediate transfer medium, fixed so as to be in contact with and rotatable around a rotation axis perpendicular to the second transport direction, and a coating layer on the peripheral surface thereof formed of synthetic resin or synthetic rubber ; The latent image carrier cleaning roller is driven to rotate in a direction in which a surface of the latent image carrier cleaning roller contacting the latent image carrier moves in a direction opposite to the first transport direction. For chestnut First driving means for removing the residual developer on the latent image carrier after the primary transfer by the ning roller, and a surface of the cleaning roller for the intermediate transfer medium that contacts the intermediate transfer medium is in the second transport direction. A second driving unit configured to rotate the intermediate transfer medium cleaning roller in a direction to move in the opposite direction, and to remove residual developer on the intermediate transfer medium after the secondary transfer by the intermediate transfer medium cleaning roller; It is characterized by having prepared.
[0011]
According to this configuration, the toner image in which the electrostatic latent image is visualized by the developer having a toner concentration of about 5 to 40% by weight is conveyed in the first conveyance direction while being held on the latent image carrier. Primary transfer is performed on the intermediate transfer medium at the primary transfer position. The toner image transferred to the intermediate transfer medium is transported in the second transport direction and secondarily transferred to the recording medium at the secondary transfer position. Then, the cleaning is performed in such a direction that the peripheral surface of the latent image carrier cleaning roller that contacts the latent image carrier downstream of the primary transfer position in the first conveyance direction moves in the direction opposite to the first conveyance direction. The roller is driven to rotate, and the residual developer on the latent image carrier after the primary transfer is removed by the latent image carrier cleaning roller. Further, the cleaning roller is arranged in such a direction that the peripheral surface of the intermediate transfer medium cleaning roller that contacts the intermediate transfer medium downstream of the second transfer position in the second transport direction moves in a direction opposite to the second transport direction. Driven by rotation, residual developer on the intermediate transfer medium after the secondary transfer is removed by the intermediate transfer medium cleaning roller.
[0012]
Here, the cleaning roller for the latent image carrier is fixed so that its peripheral surface comes into contact with the latent image carrier, and the cleaning roller for the latent image carrier is pressed against the latent image carrier with a constant pressure. Since the configuration is not adopted, deformation of the latent image carrier cleaning roller is prevented in advance. Similarly, the cleaning roller for the intermediate transfer medium is fixed so that its peripheral surface comes into contact with the intermediate transfer medium, and a configuration is adopted in which the intermediate transfer medium cleaning roller is pressed against the intermediate transfer medium with a constant pressure. Therefore, deformation of the cleaning roller for the intermediate transfer medium is prevented in advance. As a result, the nip width formed by the latent image carrier and the latent image carrier cleaning roller and the nip width formed by the intermediate transfer medium and the intermediate transfer medium cleaning roller do not vary. As a result, it is possible to ensure good durability performance and prevent deterioration in cleaning performance.
[0013]
In addition, a first voltage applying unit that applies an AC bias voltage between the latent image carrier cleaning roller and the latent image carrier is provided. Accordingly , since the force in the contact / separation direction with respect to the latent image carrier acts on the charged toner in the residual developer, the adhesion force of the toner to the latent image carrier can be reduced, thereby improving the cleaning performance for the toner. Can be improved. Further, the latent image carrier can be neutralized by the AC bias voltage applied by the first voltage applying means. Accordingly, it is not necessary to separately provide a static eliminating unit which is essential when the electrostatic latent image is repeatedly formed on the latent image carrier, and the apparatus configuration can be simplified and downsized.
[0014]
Further, there is provided a second voltage applying means for applying an AC bias voltage between the intermediate transfer medium cleaning roller and the intermediate transfer medium . Accordingly , since the force in the contact / separation direction with respect to the intermediate transfer medium acts on the charged toner in the residual developer, the adhesion force of the toner to the intermediate transfer medium can be reduced, thereby improving the cleaning performance for the toner. be able to.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an internal configuration of a printer which is an embodiment of an image forming apparatus according to the present invention, and FIG. 2 is a block diagram showing an electrical configuration of the printer. This printer is a wet development type image forming apparatus that forms a single color image using a developer containing black (K) toner, and a print command signal including an image signal is sent from an external device such as a host computer to the main control unit. 100, the engine control unit 110 controls each part of the engine unit 1 in accordance with a control signal from the main control unit 100, and conveys it from the paper feed cassette 3 disposed in the lower part of the apparatus main body 2. An image corresponding to the image signal is printed out on transfer paper, copy paper, and paper (hereinafter referred to as “recording medium”) 4.
[0019]
The engine unit 1 includes a photoreceptor unit 10, an exposure unit 20, a developing unit 30, a transfer unit 40, a cleaning unit 50, and the like. Among these units, the photoreceptor unit 10 includes a photoreceptor 11 and a charging unit 12. The developing unit 30 includes a developing roller 31 and the like. Further, the transfer unit 40 includes an intermediate transfer roller 41 and the like. Further, the cleaning unit 50 includes a cleaning roller 51, a cleaning blade 52, and the like.
[0020]
In the photoconductor unit 10, the photoconductor 11 is provided so as to be rotatable in an arrow direction 15 in FIG. 1 (clockwise direction in the drawing). A charging unit 12, a developing roller 31, an intermediate transfer roller 41, a cleaning roller 51, and a cleaning blade 52 are disposed around the photoconductor 11 along the rotation direction 15. Further, a surface area between the charging unit 12 and the developing roller 31 is an irradiation area of the light beam 21 from the exposure unit 20. In this embodiment, the charging unit 12 includes a charging roller, and a charging bias is applied from the charging bias generation unit 111 to uniformly charge the outer peripheral surface of the photoconductor 11 to a predetermined surface potential Vd (for example, Vd = DC + 600 V). It has a function as a charging means.
[0021]
A light beam 21 formed by, for example, a laser is irradiated from the exposure unit 20 toward the outer peripheral surface of the photoconductor 11 uniformly charged by the charging unit 12. The exposure unit 20 exposes the photosensitive member 11 with a light beam 21 in accordance with a control command given from the exposure control unit 112, and forms an electrostatic latent image corresponding to an image signal on the photosensitive member 11. It has a function as an exposure means. For example, when a print command signal including an image signal is given from an external device such as a host computer to the CPU 101 of the main control unit 100 via the interface 102, the CPU 113 controls the exposure control unit in response to a command from the CPU 101 of the main control unit 100. A control signal corresponding to the image signal is output to 112 at a predetermined timing. Then, in response to a control command from the exposure control unit 112, the light beam 21 is irradiated from the exposure unit 20 to the photoconductor 11, and an electrostatic latent image corresponding to the image signal is formed on the photoconductor 11.
[0022]
The electrostatic latent image formed in this way is visualized by toner supplied from the developing roller 31 of the developing unit 30. The developing unit 30 includes, in addition to the developing roller 31, a tank 33 that stores the developing solution 32, a coating roller 34 that pumps up the developing solution 32 stored in the tank 33 and applies the developing solution 31 to the developing roller 31 at the coating position 34a. A regulating blade 35 that uniformly regulates the thickness of the upper developer layer, a cleaning blade 36 that removes the developer remaining on the developing roller 31 after supplying the toner to the photosensitive member 11, and a memory 37 (FIG. 2) described later. I have. The developing roller 31 rotates at a circumferential speed substantially equal to that of the photoconductor 11 in the direction of following the photoconductor 11 (counterclockwise in FIG. 1). The application roller 34 rotates in the same direction as the developing roller 31 (counterclockwise in the figure) at a peripheral speed of about twice.
[0023]
In the present embodiment, the developer 32 is a toner composed of a color pigment, an adhesive such as an epoxy resin that adheres the color pigment, a charge control agent that gives a predetermined charge to the toner, a dispersant that uniformly disperses the color pigment, and the like. Is dispersed in a liquid carrier. In this embodiment, for example, silicone oil such as polydimethylsiloxane oil is used as the liquid carrier, the toner concentration is 5 to 40% by weight, and the low-concentration developer (toner concentration is 1 to 2) often used in the wet development system. The concentration is higher than (% by weight). The type of the liquid carrier is not limited to silicone oil, and the viscosity of the developer 32 is determined by the liquid carrier to be used, each material constituting the toner, the toner concentration, etc. In this embodiment, For example, the viscosity is 100 to 10000 mPa · s, preferably 50 to 6000 mPa · s.
[0024]
In this embodiment, the distance between the photoconductor 11 and the developing roller 31 (development gap = thickness of the developer layer) is set to, for example, 5 to 40 μm, and the development nip width (the developer layer is the photoconductor 11 and the developing roller 31). In this embodiment, the distance in the circumferential direction in contact with both is set to 5 mm, for example. In the case of the low-concentration developer described above, a development gap of 100 to 200 μm is required to increase the amount of toner, and in this embodiment using a high-concentration developer, the development gap can be shortened. Accordingly, the moving distance of the toner moving in the developer by electrophoresis is shortened, and a higher electric field is generated even when the same developing bias is applied, so that the developing efficiency can be improved and the developing can be performed at a high speed. It will be possible.
[0025]
In the developing unit 30 having such a configuration, the developer 32 stored in the tank 33 is pumped up by the application roller 34, and the thickness of the developer layer on the application roller 34 is uniformly regulated by the regulation blade 35. The developing solution 32 adheres to the surface of the developing roller 31 and is conveyed to the developing position 16 facing the photosensitive member 11 as the developing roller 31 rotates. For example, the toner in the developer is positively charged by the action of a charge control agent or the like.
[0026]
Then, a developing solution carried on the developing roller 31 at the developing position 16 is supplied from the developing roller 31 and adheres to the photosensitive member 11, and a developing bias Vb (for example, Vb) applied to the developing roller 31 from the developing bias generator 114. = DC + 400V), the toner moves in the developing solution from the developing roller 31 to the photoconductor 11, and the electrostatic latent image is visualized. Further, the developer remaining on the developing roller 31 without adhering to the photoconductor 11 is scraped off by the cleaning blade 36 and returns to the tank 33 by its own weight.
[0027]
The toner image formed on the photoconductor 11 as described above is conveyed to a primary transfer position 44 facing the intermediate transfer roller 41 as the photoconductor 11 rotates. The intermediate transfer roller 41 rotates in a direction (counterclockwise in FIG. 1) 46 that follows the photosensitive member 11 at a peripheral speed substantially equal to that of the photosensitive member 11, and a primary transfer bias (for example, DC) from the transfer bias generator 115. When −400 V) is applied, the toner image on the photoconductor 11 is primarily transferred to the intermediate transfer roller 41. Residual charges and residual developer on the photoreceptor 11 after the primary transfer are removed by the cleaning roller 51 and the cleaning blade 52. The cleaning roller 51 will be described in detail later.
[0028]
A secondary transfer roller 42 is disposed opposite to an appropriate position of the intermediate transfer roller 41 (vertically below the intermediate transfer roller 41 in FIG. 1), and the primary transfer toner image primarily transferred to the intermediate transfer roller 41 is the intermediate transfer roller. As the roller 41 rotates, the toner is conveyed to a secondary transfer position 45 facing the secondary transfer roller 42. On the other hand, the recording medium 4 accommodated in the paper feed cassette 3 is conveyed to the secondary transfer position 45 by a conveyance drive unit (not shown) in synchronization with the conveyance of the primary transfer toner image. The secondary transfer roller 42 rotates at a peripheral speed equal to that of the intermediate transfer roller 41 in a direction (clockwise in FIG. 1) following the intermediate transfer roller 41, and the secondary transfer bias ( For example, when −100 μA) is applied under constant current control, the toner image on the intermediate transfer roller 41 is secondarily transferred to the recording medium 4. The residual developer on the intermediate transfer roller 41 after the secondary transfer is removed by the cleaning roller 43 and the cleaning blade 46. The cleaning roller 43 will be described in detail later.
[0029]
The recording medium 4 on which the toner image is secondarily transferred in this way is conveyed along a predetermined transfer paper conveyance path 5 (indicated by a one-dot chain line in FIG. 1), and the toner image is fixed by the fixing unit 6. It is discharged to the discharge tray provided in the. Further, an operation display panel 7 including a liquid crystal display and a touch panel, for example, is disposed on the upper surface of the apparatus main body 2, and accepts operation instructions from the user and displays predetermined information to notify the user.
[0030]
Thus, in this embodiment, the photosensitive member 11 corresponds to the “latent image carrier” of the invention, the developing unit 30 corresponds to the “developing unit” of the invention, and the intermediate transfer roller 41 corresponds to “ The transfer bias generator 115 corresponds to the “intermediate transfer medium”, the “primary transfer unit” of the present invention, and the secondary transfer roller 42 and the transfer bias generator 115 correspond to the “secondary transfer unit” of the present invention. To do.
[0031]
In FIG. 2, the main control unit 100 includes an image memory 103 for storing an image signal given from an external device via an interface 102, and the CPU 101 receives a print command signal including the image signal from the external device. When it is received via the interface 102, it is converted into job data in a format suitable for the operation instruction of the engine unit 1 and sent to the engine control unit 110.
[0032]
The memory 116 of the engine control unit 110 includes a ROM that stores a control program for the CPU 113 including preset fixed data, a RAM that temporarily stores control data for the engine unit 1, calculation results by the CPU 113, and the like. The CPU 113 stores data relating to the image signal sent from the external device via the CPU 101 in the memory 116.
[0033]
The memory 37 of the developing unit 30 stores data relating to the manufacturing lot, usage history, built-in toner characteristics, remaining amount of the developer 32, toner density, and the like. The memory 37 is electrically connected to the communication unit 38, and the communication unit 38 is attached to the tank 33, for example. When the developing unit 30 is attached to the apparatus main body 2, the communication unit 38 is arranged to face the communication unit 117 of the engine control unit 110 within a predetermined distance, for example, within 10 mm. Data can be transmitted and received in a non-contact state by wireless communication. As a result, the CPU 113 manages various information such as consumables management related to the developing unit 30.
[0034]
In this embodiment, data transmission / reception is performed in a non-contact manner using electromagnetic means such as wireless communication. For example, a connector is provided in each of the apparatus main body 2 and the developing unit 30, and the apparatus main body 2 is provided with a connector. When the developing unit 30 is mounted, data transmission and reception may be performed by mechanically fitting both connectors. The memory 37 is preferably a non-volatile memory that can store the data even when the power is off or the developing unit 30 is detached from the apparatus main body 2. Examples of the non-volatile memory include a flash memory. EEPROM, ferroelectric memory, or the like can be used.
[0035]
FIG. 3 is a diagram showing the cleaning roller 51 and the photoconductor 11. As shown in FIG. 1, the cleaning roller 51 is fixed to the apparatus main body 2 so that its peripheral surface comes into contact with the photoconductor 11 on the downstream side in the rotation direction 15 with respect to the primary transfer position 44, and rotates. It is provided so as to be rotatable around a rotation axis orthogonal to the direction 15. When the roller drive motor 53 (FIG. 2) is rotationally driven by the motor drive unit 118 (FIG. 2), the cleaning roller 51 has a predetermined direction in the direction opposite to the direction in which the photoreceptor 11 is driven (clockwise in FIG. 1). It rotates at the peripheral speed S1. Accordingly, the cleaning roller 51 removes the developer remaining on the surface of the photoconductor 11 from the photoconductor 11 after the completion of the primary transfer.
[0036]
As shown in FIG. 3, an AC bias generator 119 is connected between the cleaning roller 51 and the photoconductor 11. When the AC bias generator 119 is driven by a control signal from the CPU 113, an AC bias is applied between the cleaning roller 51 and the photoconductor 11. By this AC bias, the force in the contact / separation direction with respect to the photoconductor 11 alternately acts on the charged toner in the residual developer on the photoconductor 11, so that the adhesion force of the toner to the photoconductor 11 can be reduced. Thus, the toner can be reliably removed from the photoconductor 11 by the cleaning roller 51.
[0037]
As shown in FIG. 3, the nip width formed by the cleaning roller 51 and the photoreceptor 11 is set to L1. If the nip width L1 is small, the desired cleaning performance cannot be obtained. If the nip width L1 is excessive, the durability of the cleaning roller 51 and the photosensitive member 11 deteriorates and the durability performance is lowered. The nip width L1 can be set to an appropriate value by selecting a material having an appropriate rigidity from a synthetic resin or a synthetic rubber as a material for forming the peripheral surface (coating layer) of the cleaning roller 51.
[0038]
As shown in FIG. 1, a cleaning blade 54 is in contact with the cleaning roller 51, and the developer removed from the photoconductor 11 by the cleaning roller 51 is scraped off from the cleaning roller 51 by the cleaning blade 54. For example, it is collected in a waste liquid tank (not shown).
[0039]
FIG. 4 is a view showing the cleaning roller 43 and the intermediate transfer roller 41. As shown in FIG. 1, the cleaning roller 43 is fixed to the apparatus main body 2 so that its peripheral surface comes into contact with the intermediate transfer roller 41 on the downstream side in the rotation direction 46 with respect to the secondary transfer position 44, and It is provided so as to be rotatable around a rotation axis orthogonal to the rotation direction 46. When the roller drive motor 48 (FIG. 2) is rotationally driven by the motor drive unit 120 (FIG. 2), the cleaning roller 43 rotates in a direction opposite to the direction in which the intermediate transfer roller 41 is driven (counterclockwise in FIG. 1). It rotates at a predetermined peripheral speed S2. As a result, the cleaning roller 43 removes the developer remaining on the surface of the intermediate transfer roller 41 from the intermediate transfer roller 41 after the end of the secondary transfer.
[0040]
As shown in FIG. 4, an AC bias generator 121 is connected between the cleaning roller 43 and the intermediate transfer roller 41. When the AC bias generator 121 is driven by a control signal from the CPU 113, an AC bias is applied between the cleaning roller 43 and the intermediate transfer roller 41. By this AC bias, force in the contact / separation direction with respect to the intermediate transfer roller 41 alternately acts on the charged toner in the residual developer on the intermediate transfer roller 41, so that the adhesion force of the toner to the intermediate transfer roller 41 can be reduced. Thus, the toner can be reliably removed from the intermediate transfer roller 41 by the cleaning roller 43.
[0041]
As shown in FIG. 4, the nip width formed by the cleaning roller 43 and the intermediate transfer roller 41 is set to L2. As described above, if the nip width L2 is small, the desired cleaning performance cannot be obtained. If the nip width L2 is excessive, the durability of the cleaning roller 43 and the intermediate transfer roller 41 deteriorates. Has been. The nip width L2 can be set to an appropriate value by selecting a material having an appropriate rigidity from a synthetic resin or a synthetic rubber as a material for forming the peripheral surface (coating layer) of the cleaning roller 43.
[0042]
As shown in FIG. 1, a cleaning blade 49 is in contact with the cleaning roller 43, and the developer removed from the intermediate transfer roller 41 by the cleaning roller 43 is scraped off from the cleaning roller 43 by the cleaning blade 49. For example, it is collected in a waste liquid tank (not shown).
[0043]
Thus, in this embodiment, the cleaning roller 51 corresponds to the “latent image carrier cleaning roller” of the present invention, and the roller drive motor 53 and the motor drive unit 118 correspond to “first drive means” of the present invention. The AC bias generator 119 corresponds to the “first voltage applying unit” of the present invention, the cleaning roller 43 corresponds to the “cleaning roller for intermediate transfer medium” of the present invention, and the roller driving motor 48 and the motor driving unit 120. Corresponds to the “second driving means” of the present invention, and the AC bias generator 121 corresponds to the “second voltage applying means” of the present invention.
[0044]
Next, the cleaning performance of the cleaning roller 51 and the cleaning roller 43 will be described. The nip widths L1 and L2 by the rollers 51 and 43 are set to L1> L2. Since the cleaning performance can be improved with a larger nip width, the cleaning roller 51 can obtain higher cleaning performance than the cleaning roller 43 by setting L1> L2.
[0045]
Further, the circumferential speeds S1 and S2 of the cleaning rollers 51 and 43 are set to S1> S2. As described above, the peripheral speed of the photoconductor 11 and the peripheral speed of the intermediate transfer roller 41 are set to substantially the same speed. Accordingly, when S1> S2, the relative speed between the cleaning roller 51 and the photoconductor 11 is greater than the relative speed between the cleaning roller 43 and the intermediate transfer roller 41. Since the cleaning performance can be improved when the relative speed is larger, the cleaning performance of the cleaning roller 51 can be higher than that of the cleaning roller 43 by setting S1> S2.
[0046]
Here, the developer decreases with each transfer. Therefore, it is considered that there is more developer remaining on the photoconductor 11 after the primary transfer than the developer remaining on the intermediate transfer roller 41 after the secondary transfer. That is, the cleaning roller 51 requires higher cleaning performance than the cleaning roller 43. Therefore, by setting L1> L2 and S1> S2, appropriate cleaning performance can be ensured for the cleaning roller 43 and the cleaning roller 51, respectively.
[0047]
As described above, according to the present embodiment, the peripheral surface of the cleaning roller 51 contacts the photoconductor 11 on the downstream side in the rotational direction 15 from the primary transfer position 44 and contacts the photoconductor 11 of the cleaning roller 51. Since the cleaning roller 51 is rotationally driven by the roller drive motor 53 in such a direction that the contact surface moves in the direction opposite to the rotational direction 15 of the photoconductor 11, the residual developer on the photoconductor 11 after the primary transfer is surely obtained. Can be removed.
[0048]
In this case, the cleaning roller 51 is fixed to the apparatus main body 2 so that the peripheral surface thereof is in contact with the photosensitive member 11, and the configuration in which the cleaning roller 51 is pressed against the photosensitive member 11 with a constant pressure is not employed. The deformation of the cleaning roller 51 can be prevented in advance. As a result, it is possible to ensure good durability performance and prevent deterioration in cleaning performance.
[0049]
In addition, according to the present embodiment, the AC bias is applied between the cleaning roller 51 and the photoconductor 11 by the AC bias generator 119, so that the adhesion force of the toner to the photoconductor 11 can be reduced. Thus, the toner can be removed efficiently. Further, since the charge removal of the photoconductor 11 can be performed by applying this AC bias, it is not necessary to separately provide a charge removal means such as an LED, and the apparatus configuration can be simplified and the apparatus main body can be downsized.
[0050]
Further, according to the present embodiment, the circumferential surface of the cleaning roller 43 contacts the intermediate transfer roller 41 on the downstream side in the rotation direction 46 from the secondary transfer position 45, and the surface of the cleaning roller 43 that contacts the intermediate transfer roller 41. Since the cleaning roller 43 is rotationally driven by the roller drive motor 48 in the direction in which the toner moves in the direction opposite to the rotational direction 46 of the intermediate transfer roller 41, the residual developer on the intermediate transfer roller 41 after the secondary transfer is surely obtained. Can be removed.
[0051]
In this case, the cleaning roller 43 is fixed to the apparatus main body 2 so that the peripheral surface thereof is in contact with the intermediate transfer roller 41, and a configuration in which the cleaning roller 43 is pressed against the intermediate transfer roller 41 with a constant pressure is not employed. Therefore, it is possible to prevent the cleaning roller 43 from being deformed. As a result, it is possible to ensure good durability performance and prevent deterioration in cleaning performance.
[0052]
Further, according to the present embodiment, the AC bias is applied between the cleaning roller 43 and the intermediate transfer roller 41 by the AC bias generator 121, so that the adhesion force of the toner to the intermediate transfer roller 41 is reduced. As a result, the toner can be efficiently removed.
[0053]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the spirit thereof. Although the cleaning roller 51 is provided, the present invention is not limited to this, and a plurality of cleaning rollers arranged side by side in the rotation direction 15 may be provided. Similarly, in the above-described embodiment, the single cleaning roller 43 is provided. However, the present invention is not limited to this, and a plurality of cleaning rollers arranged side by side in the rotation direction 46 may be provided.
[0054]
In the above embodiment, the cleaning blade 52 is provided. However, when the residual developer can be completely removed by the cleaning roller 51, the cleaning blade 52 may be omitted. Similarly, the cleaning blade 47 is provided in the above embodiment, but the cleaning blade 47 may be omitted when the residual developer can be completely removed by the cleaning roller 43.
[0055]
In the above embodiment, both the cleaning roller 51 and the cleaning roller 43 are provided. However, the present invention is not limited to this. For example, only the cleaning roller 51 may be provided. In this embodiment, the photoconductor 11 corresponds to the “image carrier” of the present invention, the transfer bias generator 115 corresponds to the “transfer means” of the present invention, and the cleaning roller 51 corresponds to the “cleaning roller” of the present invention. The roller drive motor 53 and the motor drive unit 118 correspond to the “drive unit” of the present invention, and the AC bias generation unit 119 corresponds to the “voltage application unit” of the present invention. At this time, the intermediate transfer roller 41 corresponds to the transfer medium.
[0056]
Conversely, a configuration including only the cleaning roller 43 may be employed. In this embodiment, the intermediate transfer roller 41 corresponds to the “image carrier” of the present invention, the secondary transfer roller 42 and the transfer bias generator 115 correspond to “transfer means” of the present invention, and the cleaning roller 43 corresponds to the present invention. The roller driving motor 48 and the motor driving unit 120 correspond to the “driving unit” of the present invention, and the AC bias generating unit 121 corresponds to the “voltage applying unit” of the present invention. At this time, the recording medium 4 corresponds to the transfer medium.
[0057]
In the above-described embodiment, the intermediate transfer roller 41 is provided, and the toner image on the photoconductor 11 is primarily transferred to the intermediate transfer roller 41 at the primary transfer position 44 and then is transferred by the secondary transfer roller 42 at the secondary transfer position 45. However, the present invention is not limited to this. For example, the intermediate transfer roller 41 is omitted and the secondary transfer roller 42 is disposed at the primary transfer position 44 so that the toner image on the photoconductor 11 is directly transferred. It may be configured to transfer to the recording medium 4. In this embodiment, the photoconductor 11 corresponds to the “image carrier” of the present invention, and the transfer bias generator 115 and the secondary transfer roller 42 correspond to “transfer means” of the present invention. At this time, the recording medium 4 corresponds to the transfer medium.
[0058]
In the above embodiment, a printer that prints an image supplied from an external device such as a host computer on transfer paper is described. However, the present invention is not limited to this, and includes a copying machine, a facsimile machine, and the like. The present invention can be applied to a general electrophotographic image forming apparatus. In the above-described embodiment, the present invention is applied to an image forming apparatus for monochrome printing. However, the application target of the present invention is not limited to this, and the present invention can also be applied to a color image forming apparatus. .
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an internal configuration of a printer according to an embodiment of the invention.
FIG. 2 is a block diagram showing an electrical configuration of the printer.
FIG. 3 is a view showing a cleaning roller and a photoreceptor.
FIG. 4 is a diagram illustrating a cleaning roller and an intermediate transfer roller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Photosensitive body (image carrier, latent image carrier), 20 ... Developing unit (developing means), 41 ... Intermediate transfer roller (image carrier, intermediate transfer medium), 42 ... Secondary transfer roller (transfer means, 2) (Next transfer means), 43, 51 ... cleaning roller, 48 ... roller drive motor (drive means, second drive means), 53 ... roller drive motor (drive means, first drive means), 113 ... CPU, 115 ... transfer bias Generation unit (transfer unit, primary transfer unit, secondary transfer unit), 118 ... motor drive unit (drive unit, first drive unit), 119 ... AC bias generation unit (voltage application unit, first voltage application unit), 120... Motor driving section (driving means, second driving means) 121... AC bias generating section (voltage applying means, second voltage applying means)

Claims (2)

A latent image bearing member capable of carrying the electrostatic latent image on the surface and carrying the toner image in which the electrostatic latent image is visualized while carrying the toner image;
Developing means for forming the toner image by dispersing a toner in a liquid carrier and supplying a developer having a toner concentration of about 5 to 40% by weight to the latent image carrier;
An intermediate transfer medium capable of being conveyed in the second conveying direction while carrying a toner image;
Primary transfer means for primarily transferring a toner image on the latent image carrier to the intermediate transfer medium at a predetermined primary transfer position;
Secondary transfer means for secondary transfer of the toner image transported in the second transport direction from the primary transfer position on the intermediate transfer medium toward the predetermined secondary transfer position to the recording medium at the secondary transfer position When,
The peripheral surface of the latent image carrier is fixed to the latent image carrier downstream of the primary transfer position in the first transport direction, and rotates around a rotation axis orthogonal to the first transport direction. A latent image carrier cleaning roller provided freely and having a coating layer on its peripheral surface made of synthetic resin or synthetic rubber ;
The peripheral surface of the intermediate transfer medium is fixed to the secondary transfer position on the downstream side in the second transport direction so that its peripheral surface is in contact with the secondary transfer position, and is rotatable around a rotation axis perpendicular to the second transport direction. A cleaning roller for an intermediate transfer medium, the covering layer of which is formed of synthetic resin or synthetic rubber ,
The latent image carrier cleaning roller is driven to rotate in a direction in which a surface of the latent image carrier cleaning roller contacting the latent image carrier moves in a direction opposite to the first transport direction. First driving means for removing residual developer on the latent image carrier after the primary transfer by a cleaning roller;
The intermediate transfer medium cleaning roller is rotationally driven in a direction in which the surface of the intermediate transfer medium cleaning roller that contacts the intermediate transfer medium moves in a direction opposite to the second transport direction. Second driving means for removing residual developer on the intermediate transfer medium after secondary transfer ;
First voltage applying means for applying an AC bias voltage between the latent image carrier cleaning roller and the latent image carrier;
A second voltage applying means for applying an AC bias voltage between the intermediate transfer medium cleaning roller and the intermediate transfer medium;
A first cleaning blade that contacts the latent image carrier cleaning roller and removes the developer on the latent image carrier cleaning roller;
An image forming apparatus comprising: a second cleaning blade that contacts the intermediate transfer medium cleaning roller and removes the developer on the intermediate transfer medium cleaning roller . Further comprising a waste tank,
The developer removed from the latent image carrier cleaning roller by the first cleaning blade is collected in the waste liquid tank;
The image forming apparatus according to claim 1 , wherein the developer removed from the intermediate transfer medium cleaning roller by the second cleaning blade is collected in the waste liquid tank .

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