JP2001022166A - Image forming device - Google Patents

Abstract

(57) Abstract: An image forming apparatus capable of preventing the influence of cleaning of a charging member by a cleaning member from affecting patch control even when performing patch control. When a patch control (37) is performed by a CPU (38), a motor (22) is driven immediately before the patch control (37) to bring a cleaning member into contact with a charging member, and then the motor (22) is stopped and a motor (36) is driven. Cleaning is performed. Therefore, after the charging member is cleaned, the patch control 37 is performed, so that at the time of the patch control, the surface of the charging member has already been cleaned of foreign matter such as toner. Then, in this state, the image density adjustment is performed by the patch control 37 and the cleaning of the charging member is not performed thereafter, so that a stable and good image quality is maintained until the cleaning operation immediately before the next patch control 27 is performed. Will be kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms an image by charging a photosensitive member by bringing a charging member such as a charging roller into contact with the photosensitive member and forming an electrostatic latent image on the charged photosensitive member. The present invention belongs to the technical field of an image forming apparatus, and particularly to the technical field of an image forming apparatus configured to perform cleaning of a charging member by a cleaning member and patch control for correcting shading of an image.

[0002]

2. Description of the Related Art An image forming apparatus such as an electrostatic copying machine or a printer is provided with a charging device for charging a photosensitive member, and corona charging has been widely used as a charging device. However, since the corona charging generates ozone and nitrogen oxides and adheres to the surface of the photoreceptor, there is a problem that an image defect is caused.

A contact charging system in which a charging member made of, for example, urethane rubber or the like to which a voltage is applied is brought into contact with the photosensitive member to charge the photosensitive member is proposed in Japanese Patent Laid-Open No. 63-149668. Have been. According to the contact charging method, the problem caused by the corona charging described above is solved. However, in the contact charging method, since the charging member is in contact with the photoreceptor, foreign substances such as toner on the photoreceptor slipped from the cleaning device and toner scattered from the developing device adhere to the surface of the charging member. For this reason, charging failure of the photoconductor is caused, and image deterioration occurs.

[0004] For this reason, various image forming apparatuses provided with a cleaning member for removing foreign substances such as toner adhered to the surface of the charging member have been conventionally proposed. When the cleaning member of such an image forming apparatus is constantly in contact with the charging member, the surface of the charging member is damaged and charging failure occurs. The cleaning member is brought into contact with the charging member only when cleaning the charging member, and is set to be separated from the charging member when not cleaning the charging member. In this case, the cleaning of the charging member is generally performed periodically during the non-printing operation. For example, JP-A-7-128954 discloses that cleaning of a charging member is performed every predetermined number of image formations.
Japanese Patent Application Laid-Open No. 7-128957 discloses that cleaning of a charging member is performed at predetermined time intervals.

[0005] Even if foreign matter such as toner adheres to the charging member, the above-mentioned image deterioration does not occur, and the density of the output image may change. In this case, the change in the image density is corrected by adjusting the image density without cleaning the charging member by the cleaning member. As this correction, patch control (in this case, adjusting a charging bias, a developing bias, and the like) is used. In patch control, for example, as disclosed in Japanese Patent Publication No. 7-115991, originally, in an image forming apparatus, the shading of an image may change due to a change in its use environment or a length of operation time. This is performed to correct this change in image density.

[0006]

However, when the change in image density caused by the attachment of foreign matter such as toner to the charging member is performed by such patch control,
If the cleaning operation of the charging member is performed after the patch control is performed, the density of the image may be changed even though the image density is adjusted by the patch control.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent the influence of cleaning of a charging member by a cleaning member from affecting patch control even when performing patch control. It is an object of the present invention to provide an image forming apparatus which can perform the following.

[0008]

In order to solve this problem, the present invention provides a photosensitive member on which an electrostatic latent image is formed, a charging member that contacts the photosensitive member and charges the photosensitive member, A cleaning member provided to be detachable from the charging member and cleaning the charging member, wherein the charging member is rotated by rotating the charging member in a state where the cleaning member is in contact with the charging member. In the image forming apparatus, the cleaning member is separated from the charging member except at the time of cleaning the charging member, and the charging member is controlled. At the time of cleaning, it is configured to come into contact with the charging member, and at least immediately before performing the patch control,
The cleaning device is provided with control means for controlling the cleaning member so as to clean the charging member by bringing the cleaning member into contact with the charging member.

[0009]

In the image forming apparatus of the present invention thus constructed, when the patch is controlled by the control means, the cleaning member is brought into contact with the charging member immediately before the patch control to clean the charging member. Become like Therefore, since the patch control is performed after the charging member is cleaned, at the time of the patch control, the surface of the charging member has already been removed from the dirt due to foreign substances such as toner. In this state, the image density adjustment is performed by the patch control, and the cleaning of the charging member is not performed thereafter, so that stable and good image quality is maintained until the cleaning operation immediately before the next patch control is performed. Will be

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view schematically showing a full-color intermediate transfer type image forming apparatus to which an example of an embodiment of the image forming apparatus of the present invention is applied. As shown in FIG. 1, an image forming apparatus 1 of this example includes a photoconductor (hereinafter, also referred to as OPC) 2, a charging device 3, an exposure device 4, a developing device 5, an intermediate transfer device 6, and a cleaning device 7.
And a transfer device (not shown) for transferring the intermediate transfer image transferred to the transfer belt 6a of the intermediate transfer device 6 to a transfer material such as transfer paper, and a fixing device for fixing the transfer image transferred to the transfer material. It has.

The charging device 3, the exposing device 4, the developing device 5, the intermediate transfer device 6, and the cleaning device 7 are disposed around the OPC 2 in the same order as in the conventional image forming apparatus, clockwise in FIG. I have. And OPC2,
The charging device 3, the developing device 5, and the cleaning device 7 are accommodated in one process cartridge 8 (in FIG. 1, the process cartridge 8 is schematically shown).

As shown in detail in FIG. 2, in the image forming apparatus 1 of this embodiment, the OPC 2 is accommodated in a process cartridge 8, and is rotatably supported by a frame 8a of the process cartridge 8. I have. Similarly, the charging device 3 is also accommodated in the process cartridge 8. The charging device 3 includes a charging member 9 such as a charging roller rotatably supported by a frame 8 a to contact the OPC 2 and charge the OPC 2, and a cleaning member 1 for cleaning the surface of the charging member 9.
0, a holding member 11 that is provided movably in the up, down, left and right directions and holds the cleaning member 10, a support table 12 that supports the holding member 11 fixed to the process cartridge frame 8a, and the holding member 11 and the support. A pair of a pair of members that are located between the base 12 and are contracted at predetermined intervals in the longitudinal direction of the holding member 11 and constantly urge the cleaning member 9 through the holding member 11 in a direction in which the cleaning member 9 is separated from the charging member 9. Driving means 15 for driving the holding member 11 to contact or separate the springs 13 and 14 and the cleaning member 10 with respect to the charging member 9 is provided.

On the lower surface of the holding member 11 facing the support 12, a pair of projections 16, 17 are provided at predetermined intervals in the longitudinal direction of the holding member 11 and protrude toward the support 12. . Both lower surfaces 16a, 17a of these protruding portions 16, 17 are flat surfaces, and the right side surfaces 16b, 17b in these figures are both gently inclined surfaces inclined downward to the left at the same inclination angle. ing. Similarly, on the upper surface of the support base 12 facing the holding member 11, a pair of protrusions 18, 19 are similarly arranged in the longitudinal direction of the support base 12 at the same predetermined interval as the distance between the pair of protrusions 16, 17. And projecting toward the holding member 11. These protruding portions 18 and 19 have the same cross-sectional shape as the cross-sectional shape in the longitudinal direction of the protruding portions 16 and 17 in the left-right opposite direction, and therefore, both of the upper surfaces 18a and 19a are flat surfaces. In addition, in these figures, the left side surfaces 18b and 19b are both gently inclined surfaces inclined downward to the left with the same inclination angle as the inclination angles of the right side surfaces 16b and 17b. At this time, the pair of springs 13 and 14 are also contracted between the holding member 11 and the support base 12 at substantially the same inclination as the inclination of the right side surfaces 16b and 17b and the left side surfaces 18b and 19b.

The holding member 11 is located between a contact position where the cleaning member 10 contacts the charging member 9 as shown in FIG. 2 and a separation position where the cleaning member 10 is separated from the charging member 9 as shown in FIG. Can be moved. In the contact position, the upper surfaces 18a, 19a of the protrusions 18, 19 of the support base 12
And the lower surfaces 16a and 17a of the protruding portions 16 and 17 of the holding member 11 are placed thereon, and the holding member 11 is stably supported by the support base 12. Thus, the holding member 11 makes the cleaning member 10 contact the charging member 9 stably and reliably. Also,
At the separated position, the right sides 16b, 17b of the projections 16, 17 of the holding member 11 are both placed on the inclined surfaces of the left sides 18b, 19b of the projections 18, 19 of the support base 12. The holding member 11 is supported on the support base 12 in a substantially stable state. In this separated position, the lower surfaces 16a, 17a of the protruding portions 16, 17 of the holding member 11 are supported on the floor surface 12a of the support base 12 with the right side surfaces 16b, 17b contacting the left side surfaces 18b, 19b. It can also be done. These holding members 1
1, the support base 12, and the springs 13 and 14 constitute a separating / contacting means 20 for bringing the cleaning member 10 into contact with or away from the charging member 9.

In the image forming apparatus of this embodiment, the spring 1
Although each of the pairs 3 and 14 and the projections 16 and 17; 18 and 19 is provided, any one or more of them can be provided in an arbitrary number. In that case, it is desirable that the pressure of the cleaning member 10 against the charging member 9 be as uniform as possible in the axial direction of the charging member 9. Also,
Both the protrusions 16 and 17 of the holding member 11 and the protrusions 18 and 19 of the support base 12 are provided with inclined surfaces, and these inclined surfaces are provided on one of the holding member 11 and the support base 12. You can also.

As shown in FIG. 4, a driving means 15 for driving the holding member 11 includes a housing 21 fixed to the process cartridge frame 8a, a motor 22 housed in the housing 21, and a rotation of the motor 22. A first gear 23 attached to the shaft 22a, a driving force transmission shaft 24 rotatably provided in the housing 21, and a driving force transmission shaft 24 attached to the left end in the drawing of the driving force transmission shaft 24 so as to mesh with the first gear 23; The second gear 25 having a diameter larger than that of the first gear 23, a male screw portion 26 provided on the opposite side of the second gear 25 of the driving force transmission shaft 24, and the housing 21 so as to be non-rotatable and axially movable. A connecting portion 27b provided through the housing 21 and having a female screw portion 27a screwed to the male screw portion 26 and connected to the left end of the holding member 11
And a connecting member 27 having Although not specifically shown, the connecting portion 27b of the connecting member 27 and the left end of the holding member 11 are connected by a well-known structure so as to be relatively movable only in the vertical direction in the figure. Note that the male screw portion 26 may be provided on the connecting member 27 side, and the female screw portion 27a may be provided on the driving force transmission shaft 24 side.

In the state shown in the figure, the connecting member 27 is located at the most advanced position from the housing 21. At the advanced position of the connecting member 27, the holding member 11 and the cleaning member 10 are set to the contact positions shown in FIG. . When the motor 22 is driven in the pulling direction of the connecting member 27, the rotation of the motor 22 is reduced by the first and second gears 23 and 25 and transmitted to the male screw portion 26, and the male screw portion 26 rotates. The connecting member 27 is drawn into the housing 21. The pulling-in of the connecting member 27 causes the holding member 11
Moves to the left, and the lower surfaces 16a, 17a of the protrusions 16, 17 of the holding member 11 are disengaged from the upper surfaces 18a, 19a of the protrusions 18, 19 of the support base 12. Then, the holding member 11
It is pulled downward, that is, toward the support base 12 by the spring force of the pair of springs 13 and 14. At this time, the holding member 11 is configured such that the inclined surfaces of the right side surfaces 16 b and 17 b of the protrusions 16 and 17 are
8 and 19, they move leftward and downward while being contacted and guided by the inclined surfaces of the left side surfaces 18b and 19b. As a result, the cleaning member 10 moves axially and obliquely downward with respect to the charging member 9 and separates from the charging member 9. Connecting member 2
When the set member 7 is retracted by a predetermined amount, the motor 22 is stopped, and the connecting member 27 is in the retracted position. In the retracted position of the connecting member 27, the holding member 11 and the cleaning member 10 are set to the separated positions shown in FIG. Has become.

Further, in order to set the connecting member 27 from the retracted position to the advanced position, if the motor 22 is driven to rotate in the reverse direction, the connecting member 27 advances from the housing 21 and the holding member 11 moves rightward. . At this time, the holding member 11
The inclined surfaces of the right side surfaces 16b and 17b of the protrusions 16 and 17 move upward and rightward while being guided by the inclined surfaces of the left side surfaces 18b and 19b of the protrusions 18 and 19. When the connecting member 27 advances to the maximum, the motor 22 is stopped, and the connecting member 27 is at the advanced position shown in FIG. 2, and at this advanced position of the connecting member 27, the holding member 11 and the cleaning member 10 are at the contact positions shown in FIG. It is to be set.

Next, control of cleaning of the charging member 9 by the cleaning member 10 will be described. FIG. 5 shows the cleaning member 1.
FIG. 9 is a control block diagram of cleaning by zero. As shown in FIG. 5, in the image forming apparatus 1 of this example, the cleaning member 10
And a motor 36 for driving the charging member 3 are both a central processing unit (hereinafter, referred to as a central processing unit).
(Also referred to as a CPU) 38. Also, this C
The PU 38 performs the same patch control 37 of image density adjustment as in the related art.

The CPU 38 normally operates the motor 2 with the cleaning member 10 shown in FIG.
2 is stopped, and when the charging operation is not performed, the motor 36 is stopped. The cleaning of the charging member 3 is performed when the charging member 3 does not perform the charging operation. When cleaning the charging member 3 with both the motors 22 and 36 stopped, the CPU 38
First, the motor 22 is driven to set the cleaning member 10 to the contact position as described above, and then the motor 22 is stopped. Therefore, when the cleaning member 10 comes into contact with the charging member 3, the charging member 3 is stopped. Next, the CPU 38
Drives the motor 36 to rotate the charging member 3. Thus, the charging member 3 is cleaned by the cleaning member 10. When the motor 36 is driven for a predetermined time to complete the cleaning of the charging member 3, the CPU 38 stops the motor 36,
After the cleaning member 10 is separated from the charging member 9 by driving the motor 22 in the reverse direction, the cleaning member 10 is set to the separated position as described above, and then the motor 22 is stopped and the charging member 3 is stopped.
Cleaning ends.

By the way, when the cleaning operation of the charging member 9 is performed after the patch control is performed and the density of the image is adjusted as described above, the density of the image is reduced even though the density is adjusted. It may change. Therefore,
In the image forming apparatus 1 of this example, the CPU 38 causes the cleaning member 10 to contact the charging member 9 and cleans the charging member 9 by the cleaning member 10 immediately before performing the patch control 37 as described above. I have.

The developing device 5 includes yellow, magenta, cyan, and black developing devices 28, 29, 30, and 31, similarly to the developing device of the conventional full-color image forming apparatus. Containers 28, 29, 30, 31 are OPC
Are arranged along the outer circumference of the. In this case, the arrangement order of the developing units 28, 29, 30, 31 for each color is not limited to the above-mentioned order, but is arbitrarily set. In the following description, for convenience of description, the order of the above-described colors, that is, yellow, magenta, cyan, and black, in order of each developing unit 28,
It is assumed that 29, 30, 31 are provided.

The cleaning device 7 also includes a cleaner housing 32 and a cleaning blade 33 as in the conventional full-color image forming apparatus. In that case, the cleaner housing 32 is formed integrally with the frame 8a of the process cartridge 8 as shown. The cleaner housing 32 may be formed separately from the frame 8a and attached to the frame 8a.

As described above, in the image forming apparatus 1 of this embodiment, the OPC 2, the charging member 9, and the cleaning member 1 for the charging member 9 are provided.
0, a separating unit 20 for separating the cleaning member 10 from the charging member 9, a driving unit 15 for driving the separating unit 20, the developing device 5, and the cleaning device 7 are housed in one process cartridge 8. (Note that it is not shown that the developing device 5 and the cleaning device 7 are housed in the process cartridge 8, but they are also housed in the process cartridge 8 in this example in the same manner as in the related art.) . Reference numerals 34 and 35 shown in FIGS. 2 and 3 are conductive wires for electrically connecting the motor 22 to a power supply on the image forming apparatus main body side.

The operation of the thus configured image forming apparatus 1 of this embodiment will be described. First, at normal times, the cleaning member 10 is set at the separated position shown in FIG. 3 and is separated from the charging member 9. In forming an image, the surface of the OPC 2 is charged by the charging member 9 in the same manner as a conventional general image forming apparatus, and then the image is exposed as an electrostatic latent image on the charged portion of the OPC 2 by the exposure device 4. . And this OPC
The electrostatic latent images on 2 are sequentially developed by yellow, magenta, cyan, and black developing units 28, 29, 30, and 31, and are visualized. At this time, the density of the developed image is measured, and the density is adjusted by patch control according to the measurement result. Further, the developed image on the OPC 2 is primary-transferred to the intermediate transfer device 6 and sent to a transfer device (not shown). After color matching is performed by this transfer device and transferred to a transfer material (not shown), fixing is performed. By fixing by a device (not shown), a desired image can be obtained on the transfer material.

After the developed image is transferred to the transfer material, the residual toner remaining on the OPC 2 is removed by the cleaning blade 33 of the cleaning device 7 and stored in the cleaner housing 32. Thus, the image forming apparatus 1 completes the image formation, and after the OPC 2 is neutralized, the OPC 2 is charged again by the charging member 9 for the next image formation, and the same image forming process is performed thereafter.

After the transfer, the residual toner remaining on the OPC 2 is
2 and is accommodated in the cleaner housing 32, but a part thereof is not removed, but passes through the cleaning blade 33 and moves toward the charging member 9, and adheres to the charging member 9. Become like Further, the toner scattered from the developing device during the image formation for a predetermined period may adhere to the charging member 9, or the scattered dust and dust around the photoconductor 2 may adhere to the charging member 9. . For this reason, in the image forming apparatus 1 of this example, the cleaning process is periodically performed, and the foreign material attached to the charging member 9 is removed by the cleaning member 10.

In this cleaning step, first, the motor 22 is driven in a predetermined rotation direction, and the cleaning member 1 is driven as described above.
0 is set to the contact position shown in FIG. In this state, the charging member 9 is rotated, and the foreign material attached to the charging member 9 is removed by the cleaning member 10.
The foreign matter removed by the cleaning member 10 is stored in the cleaner housing 32 in the process cartridge 8 or is contained in the process cartridge 8.
When a storage unit is provided separately from the storage unit 2, the storage unit is stored in the storage unit. When the charging member 9 is rotated for a predetermined time, the charging member 9 is stopped, and then the motor 22 is driven in the reverse rotation direction again, and the cleaning member 10 is set to the separated position shown in FIG.
Thereby, the cleaning member 10 is separated from the charging member 9,
The cleaning process ends.

As described above, according to the image forming apparatus 1 of this embodiment, since the patch control is performed after the charging member 9 is cleaned, the surface of the charging member 9 such as toner is Dirt from foreign matter has already been removed. Therefore, in this state, the image density is adjusted without being affected by the cleaning of the charging member 9 by the patch control, and the charging member 9 is not cleaned thereafter.
Until the cleaning operation immediately before performing the next patch control, stable and good image quality can be maintained.

In the image forming apparatus 1 of the above-described example, the present invention is described as being applied to a full-color image forming apparatus. However, the present invention is not limited to this. The present invention can be applied to any image forming apparatus as long as the image forming apparatus includes at least a charging member for charging the photoreceptor and a cleaning member for the charging member.

[0031]

As is apparent from the above description, according to the image forming apparatus of the present invention, the cleaning member is brought into contact with the charging member immediately before performing the patch control to clean the charging member. Therefore, when performing image density adjustment by the patch control, the charging member is not cleaned, and stable and good image quality can be maintained until the cleaning operation immediately before the next patch control is performed.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a full-color intermediate transfer type image forming apparatus to which an example of an embodiment of the image forming apparatus of the present invention is applied.

FIG. 2 is used in the image forming apparatus shown in FIG.
FIG. 3 is a diagram illustrating a photoconductor, a charging member, a cleaning member, and a driving unit housed in a process cartridge, and illustrates a state where the cleaning member is in contact with the charging member.

FIG. 3 is used in the image forming apparatus shown in FIG.
FIG. 3 is a diagram illustrating a photoconductor, a charging member, a cleaning member, and a driving unit housed in a process cartridge, and illustrates a state where the cleaning member is separated from the charging member.

4 is used in the image forming apparatus shown in FIG.
FIG. 4 is a diagram illustrating a driving unit of a cleaning member.

FIG. 5 is a control block diagram of cleaning of a cleaning member used in the image forming apparatus shown in FIG.

[Description of Signs] 1 ... Image forming apparatus, 2 ... Photoconductor (OPC), 3 ... Charging device, 4 ... Exposure device, 5 ... Developing device, 6 ... Intermediate transfer device,
7 cleaning device, 8 process cartridge, 8
a: frame of process cartridge 8, 9: charging member, 1
0: cleaning member, 11: holding member, 12: support base, 13,
14 ... spring, 15 ... drive means, 16, 17, 18, 19 ...
Projecting portion, 20: separating / contacting means, 21: housing, 22: motor for performing the separating / contacting operation of the cleaning member 10, 23: first gear,
Reference numeral 24: driving force transmission shaft, 25: second gear, 26: male screw portion, 27: connecting member, 36: motor for driving the charging member 3, 37: patch control, 38: central processing unit (CPU)

Continued on the front page (72) Inventor Yujiro Nomura 3-3-5 Yamato, Suwa-shi, Nagano Seiko-Epson F Company Term (Reference) 2H003 AA12 BB11 CC05 EE11 2H027 EC03 ED03 ED30 EE02 EE04 EF06 HB01 HB16 HB19

Claims (1)

[Claims] 1. A photoconductor on which an electrostatic latent image is formed, a charging member that contacts the photoconductor and charges the photoconductor, and a charging member that is provided so as to be capable of separating from and contacting the charging member. A cleaning member for cleaning, the cleaning member being rotated by rotating the charging member in a state where the cleaning member is in contact with the charging member, and performing image density adjustment by patch control. In the image forming apparatus, the cleaning member is separated from the charging member except when cleaning the charging member, and is in contact with the charging member when cleaning the charging member. At least immediately before performing the patch control, a control unit that controls the cleaning member so that the cleaning member is brought into contact with the charging member to clean the charging member is provided. An image forming apparatus.