JP2003140449A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that prevents the surface of a charging roller from being excessively worn or damaged, sufficiently cleans the surface of the charging roller, and prevents deterioration of image quality resulting from charging failure and ununiform charging, by controlling cleaning conditions for the surface of the charging roller in accordance with image forming conditions which determine the degree to which the surface of the charging roller is soiled with toner, added agent, etc. SOLUTION: In the image forming apparatus having a charging member for charging the surface of an image carrier while rotating in contact with the surface of the image carrier and a separable/contactable cleaning member for cleaning the surface of the charging member, a control means is provided for controlling so that the rotating speed of the charging member during a cleaning operation differs from that used in an image forming operation.

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 such as a copying machine, a printer, or a facsimile, which is capable of forming a full-color or black-and-white image using an electrophotographic method, and more specifically, a charging member. The present invention relates to an image forming apparatus having an improved cleaning operation for cleaning.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer adopting this type of electrophotographic system, the surface of an image carrier such as a photosensitive drum is uniformly charged to a predetermined potential. The image is exposed to form an electrostatic latent image on the surface of the image carrier, and the electrostatic latent image is developed with toner to visualize the electrostatic latent image on the image carrier. An image is formed on the recording medium by forming a toner image, transferring the toner image to a recording medium such as paper, and fixing the toner image.

Further, in the image forming apparatus such as the copying machine or the printer, in order to form a full color image at a high speed, yellow (Y), magenta (M), cyan (C), A plurality of image forming units that form an image of a predetermined color such as black (K) are arranged in parallel with each other, and toner images of different colors formed by the plurality of image forming units are formed on the intermediate transfer belt. Various so-called tandem-type full-color image forming apparatuses configured to perform secondary transfer collectively from the intermediate transfer belt onto the recording medium after multiple primary transfers have been proposed, and the present applicant has already proposed the product. It is also being converted.

In such an image forming apparatus, a charging device for charging the image carrier by uniformly applying an electric charge to the surface of the image carrier carrying the toner image, or a primary device on the intermediate transfer belt. In order to collectively secondarily transfer the transferred toner images onto the recording medium, a transfer charging device that applies a transfer electric field to the intermediate transfer belt is used. As these charging devices, there are known two types of charging systems, a non-contact charging system such as a scorotron or a corotron using a corona discharge, and a contact charging system using a charging roller or the like using a discharge in a minute gap. There is.

In a charging device using corona discharge, a high voltage is applied to a wire stretched so as to face the surface of an image carrier to which a charge is to be applied, so that a corona is generated between the image carrier and the wire. A discharge is generated and a predetermined charge is applied to the image carrier. Although this type of charger is excellent in charging uniformity, a large amount of discharge products such as ozone and NOx are required, so that a processing device is required, which increases the size and cost of the image forming apparatus. It has the drawback of being easy to invite. Further, dust in the air, toner, discharge products, fuser oil, and the like stain the electrode wires, resulting in uneven charging, which may cause image defects.

Therefore, in recent years, instead of the corona discharge method, a contact charging type charging device has been widely used in which a charging member is directly brought into contact with an image carrier to charge the image bearing member. In this contact charging method, a roller-shaped charging member having semiconductivity is arranged so as to contact the surface of the image bearing member, and a voltage is applied to the charging member so that in the minute voids on the image bearing member at the contact site. By generating a discharge, electric charges are applied to the image carrier. In this method, since corona discharge is not used, the amount of ozone generated is extremely small, and since the charging member is in contact with the image carrier, it is suitable for reducing the size and weight of the apparatus.

However, in such a contact type charging device, since the charging member is brought into contact with the image carrier, dirt such as toner, discharge products, dust in the air, and paper dust is easily attached to the charging member. If such dirt adheres, abnormal discharge or unstable discharge occurs, and there is a problem that image quality defects such as fog are likely to occur. The non-uniform charging due to the adhesion of dirt becomes particularly noticeable when a DC voltage is applied, and the image quality defect due to the non-uniform charging may be a fatal problem particularly for an image forming apparatus for high image quality.

Therefore, as an image forming apparatus which solves the above-mentioned problems and enables extremely stable and uniform charging without causing image quality defects for a long period of time, Japanese Patent Laid-Open No. 7-
The one disclosed in the publication 128956 has already been proposed.

The image forming apparatus according to Japanese Patent Laid-Open No. 7-128956 described above includes a rotating photoconductor, a charging member that contacts the photoconductor and charges the photoconductor while rotating, and the photoconductor of the charging member. In an image forming apparatus provided with a cleaning member for cleaning a surface that comes into contact with a body, the cleaning member is normally held in a state of being separated from the surface of the charging member, and the charging is performed at predetermined timing intervals. The cleaning member moving means for contacting the surface of the member for a certain period of time is provided.

To explain further, the above-mentioned Japanese Patent Laid-Open No. 7-1289.
In the image forming apparatus according to Japanese Patent Publication No. 56, as shown in FIG. 29, a cleaning member 102 formed in a felt shape or a brush shape is provided at the tip of an arm 100 supported swingably around a fulcrum 101. At the same time, by driving the arm 100 by a contacting / separating mechanism 105 including a solenoid 103 and a spring 104, the cleaning member 102 provided at the tip of the arm 100 is
Charging roller 10 for charging the surface of the photoconductor drum 106
It is configured to be brought into contact with and separated from the surface of 7. The contacting / separating mechanism may be a combination of a link mechanism and a cam.

[0011]

However, the above-mentioned prior art has the following problems. That is, in the case of the image forming apparatus according to Japanese Unexamined Patent Application Publication No. 7-128956, as shown in FIG. 29, regardless of the rotation speed of the photosensitive drum 206, the amount of image formation, and the like,
Cleaning member 1 formed in a felt shape or a brush shape
02 at a predetermined timing by the contact / separation mechanism 105,
By contacting the surface of the charging roller 107, the surface of the charging roller 207 is cleaned. Therefore, in the case of the above-mentioned image forming apparatus, there is a problem that the charging roller 107 is rotated too fast during cleaning, so that the surface of the charging roller 107 is excessively worn or scratched.

Further, in the case of the above image forming apparatus, since the surface of the charging roller 107 is cleaned at a predetermined timing even when a large number of high density images are formed,
There is a problem in that the cleaning of the charging roller 107 becomes insufficient and the surface of the charging roller 107 is contaminated, resulting in poor charging and deterioration of image quality due to uneven charging.

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to determine the degree to which the surface of the charging roller is contaminated by toner, external additives, and the like. By controlling the conditions for cleaning the surface of the charging roller according to the image forming conditions, the surface of the charging roller is not excessively worn or scratched, and the surface of the charging roller is sufficiently cleaned, An object of the present invention is to provide an image forming apparatus capable of preventing deterioration of image quality caused by poor charging or uneven charging.

[0014]

In order to solve the above-mentioned problems, the invention described in claim 1 is a charging member for charging the surface of an image carrier while rotating in contact with the surface of the image carrier. And an image forming apparatus including a contactable / separable cleaning member that cleans the surface of the charging member, including a control unit that controls the rotation speed of the charging member during the cleaning operation to be different from that during image formation. An image forming apparatus characterized by the above.

Here, as the "image carrier", for example,
It goes without saying that a toner image directly formed on a photoconductor drum or the like that carries the toner image is included, but the "image carrier" is not limited to the photoconductor drum and the The toner image is transferred from the drum and includes an intermediate transfer member carrying the toner image.

Further, in the invention described in claim 2, the charging member which contacts the surface of the image carrier to rotate and charges the surface of the image carrier, and the contact and separation for cleaning the surface of the charging member. An image forming apparatus comprising a cleaning member capable of cleaning is provided with a control means for varying a cleaning time by the cleaning member according to a process speed.

Further, in the invention described in claim 3, the charging member for contacting the surface of the image bearing member to charge the surface of the image bearing member while rotating, and the contact / separation for cleaning the surface of the charging member. In an image forming apparatus provided with a cleaning member capable of controlling, a rotation speed of a charging member during a cleaning operation is controlled to be different from that during image formation, and a cleaning time by the cleaning member is controlled according to a process speed. An image forming apparatus including means.

Furthermore, the invention described in claim 4 is
The image forming apparatus according to any one of claims 1 to 3, wherein the rotation speed of the charging member during the cleaning operation is variable.

According to a fifth aspect of the invention, in the image forming apparatus according to any one of the first to third aspects, there is provided a use time detecting means for detecting a use time of the charging member, and the use time is The image forming apparatus is characterized in that the cleaning condition is controlled according to the detection result of the detection unit.

Further, the invention described in claim 6 is the image forming apparatus according to any one of claims 1 to 3.
In the image forming apparatus, the rotational speeds of the image carrier and the charging member are controlled to be increased during the cleaning operation.

The invention described in claim 7 is the image forming apparatus according to any one of claims 1 to 3.
In the image forming apparatus, the speed at which the cleaning member is brought into contact with the surface of the charging member is variable during the cleaning operation.

Further, the invention described in claim 8 is the image forming apparatus according to any one of claims 1 to 3, wherein the pressing force applied when the cleaning member is brought into contact with the surface of the charging member is a process. The image forming apparatus is characterized by being variable according to the speed.

Furthermore, the invention described in claim 9 is
The image forming apparatus according to claim 1, wherein the pressing force when the cleaning member is brought into contact with the surface of the charging member is variable according to the number of pixels on which the image is formed. A characteristic image forming apparatus.

Furthermore, in the invention described in claim 10, in the image forming apparatus according to any one of claims 1 to 3, the pressing force when the cleaning member is brought into contact with the surface of the charging member is accumulated. The image forming apparatus is characterized in that it can be changed according to the number of formed images.

According to the invention described in claim 11, in the image forming apparatus according to any one of claims 1 to 3, the pressing force when the cleaning member is brought into contact with the surface of the charging member is accumulated. The image forming apparatus is characterized in that it can be changed according to the number of rotations of the image carrier.

Further, the invention described in claim 12 is
The image forming apparatus according to any one of claims 1 to 3, wherein the contacting / separating operation is performed a plurality of times during one cleaning cycle.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to the twelfth aspect, the cleaning operation different from other cleaning operations is performed at least once. is there.

Furthermore, the invention described in claim 14 is characterized in that, in the image forming apparatus according to claim 12, a cleaning operation having an operating torque different from that of other cleaning operations is performed at least once. The image forming apparatus.

According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the contacting / separating operation is performed once or a plurality of times during one cleaning cycle. , An image characterized in that the cleaning member is constantly moving

Further, in the invention described in Item 16, in the image forming apparatus according to any one of Items 1 to 3, when the cleaning member is separated from the charging member, at least one round of the charging member is performed. In the image forming apparatus, the cleaning member is in contact with the charging member.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1-1 FIG. 2 shows a tandem type digital color printer as an image forming apparatus according to Embodiment 1-1 of the present invention. FIG. 3 shows Embodiment 1-1 of the present invention.
2 shows a tandem type digital color copying machine as an image forming apparatus according to the present invention.

2 and 3, reference numeral 1 denotes a main body of a tandem type digital color printer and copying machine. In the case of a digital color copying machine, as shown in FIG. , An automatic document feeder (ADF) 3 for automatically feeding the originals 2 one by one
And the document 2 conveyed by the automatic document conveying device 3
A document reading device 4 for reading the image is provided. The document reading device 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 into a full rate mirror 7 and half rate mirrors 8 and 9.
And a CCD through a reduction optical system including the imaging lens 10.
Scanning exposure is performed on the image reading element 11 including the above, and the color material reflected light image of the original 2 is read by the image reading element 11 at a predetermined dot density (for example, 16 dots / mm).

The color material reflected light image of the document 2 read by the document reading device 4 is, for example, three-color document reflectance data of red (R), green (G), and blue (B) (each 8 bits). As IPS (Image Processing)
System) 12, and in this IPS 12,
Shading correction for reflectance data of original 2
Predetermined image processing such as positional deviation correction, lightness / color space conversion, gamma correction, frame erasing, and color / movement editing is performed. The IPS 12 is also designed to perform predetermined image processing on image data sent from a personal computer or the like.

The image data subjected to the predetermined image processing by the IPS 12 as described above is also subjected to the same IPS 12 as yellow (Y), magenta (M), cyan (C), black (K) (each 8 bits). 4 color original reproduction color material gradation data, and as described below, image forming units 13Y and 13M for yellow (Y), magenta (M), cyan (C), and black (K), respectively. 13C, 13K
ROS (Raser Output Scanne)
r) 14 and sent as ROS1 as the image exposure device
In 4, the image exposure by the laser beam LB is performed according to the document reproduction color material gradation data of a predetermined color.

By the way, in the image forming apparatus according to this embodiment, a plurality of image forming units for forming toner images of different colors are arranged in parallel, and the plurality of image forming units are arranged over the plurality of image forming units. A belt-shaped intermediate transfer member to which the toner images of the respective colors formed by the image forming units are transferred is arranged, and an image is written on the image carrier of each image forming unit below the plurality of image forming units. The image writing means for performing is arranged.

Further, in this embodiment, the transfer medium on which the toner image is transferred from the belt-shaped intermediate transfer member is conveyed from the lower side to the upper side in the vertical direction and transferred from the belt-shaped intermediate transfer member. Secondary transfer means for transferring the toner image onto the medium is provided on the side of the intermediate transfer belt.

Further, in this embodiment, an image forming unit for forming a black toner image is arranged on the most downstream side in the moving direction of the belt-shaped intermediate transfer member among the plurality of image forming units. Is configured.

That is, inside the tandem type digital color printer and copying machine main body 1, as shown in FIGS. 1, 2 and 3, yellow (Y), magenta (M), cyan (C), Four black (K) image forming units 13Y, 13M, 13C, and 13K are arranged in parallel in the horizontal direction at regular intervals.

These four image forming units 13Y,
All of 13M, 13C, and 13K have the same structure, and are roughly classified into a predetermined speed (for example, 200 mm / se).
Photoreceptor drum 1 as an image carrier that is rotationally driven in c)
5, a charging roll 16 as a charging device for uniformly charging the surface of the photosensitive drum 15, and the photosensitive drum 1
The ROS 14 as an image exposing means for exposing an image corresponding to a predetermined color on the surface of 5 to form an electrostatic latent image, and the electrostatic latent image formed on the photoconductor drum 15 with a toner of a predetermined color. A developing device 17 as a developing means for developing and a cleaning device 18 for cleaning the surface of the photosensitive drum 15 are included. These photosensitive drums 15 and the image forming members arranged around the photosensitive drums 15 are integrally formed as a unit, and are separately replaceable from the printer and the copying machine main body 1.

The ROS 14 has four image forming units 13Y, 13M, 13 as shown in FIGS.
C and 13K are configured in common, and four semiconductor lasers (not shown) are modulated according to the original reproduction color material gradation data of each color, and the laser light LB- is emitted from these semiconductor lasers.
It is configured to emit Y, LB-M, LB-C, and LB-K according to the gradation data. The above ROS1
Of course, 4 may be individually configured for each of the plurality of image forming units. Laser light LB emitted from the semiconductor laser
-Y, LB-M, LB-C, and LB-K are not shown f
The polygon mirror 19 is irradiated with light through the −θ lens and is deflected and scanned by the polygon mirror 19. Laser light LB deflected and scanned by the polygon mirror 19
-Y, LB-M, LB-C, and LB-K are provided on the photosensitive drum 1 via an imaging lens (not shown) and a plurality of mirrors.
Scanning exposure is performed obliquely from below to the exposure point on 5.

As shown in FIG. 2, the ROS 14 scans and exposes an image on the photosensitive drum 15 from below. Therefore, the ROS 14 has four image forming units 13Y, 13M, There is a risk that toner or the like will fall from the developing devices 17 of 13C and 13K and be contaminated. Therefore, the ROS 14 is hermetically sealed by the frame 20 having a rectangular parallelepiped shape, and the four laser beams LB are provided above the frame 20.
-Y, LB-M, LB-C, and LB-K are exposed on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K, so that a transparent glass window 21Y as a shield member, 21M, 21C, and 21K are provided.

From the IPS 12, yellow (Y),
Image data of each color is sequentially output to the ROS 14 provided in common to the image forming units 13Y, 13M, 13C, and 13K of each color of magenta (M), cyan (C), and black (K). Laser light LB-Y, LB-M, LB-C, LB-K emitted according to data
Is scanned and exposed on the surface of the corresponding photoconductor drum 15,
An electrostatic latent image is formed. The electrostatic latent images formed on the photosensitive drum 15 are the developing devices 17Y, 17M, 17C, 1
7K, toner images of yellow (Y), magenta (M), cyan (C), and black (K) are developed.

The image forming units 13Y, 13M,
The toner images of yellow (Y), magenta (M), cyan (C), and black (K), which are sequentially formed on the photoconductor drums 15 of 13C and 13K, are formed in the respective image forming units 13.
Four primary transfer rolls 26Y and 26 are provided on the intermediate transfer belt (belt-shaped intermediate transfer member) 25 of the transfer unit 22 arranged above Y, 13M, 13C, and 13K.
Multiple transcription by M, 26C and 26K. These primary transfer rolls 26Y, 26M, 26C and 26K are
The image forming units 13Y, 13M, 13C, and 13K are arranged on the back surface side of the intermediate transfer belt 25 corresponding to the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K. In this embodiment, a roll adjusted to a desired volume resistance value is used. A transfer bias power source (not shown) is connected to the primary transfer rolls 26Y, 26M, 26C, and 26K, and a transfer bias having a polarity opposite to the predetermined toner polarity (positive polarity in this embodiment) is predetermined. Is applied at the timing of.

Further, as shown in FIG. 2, the intermediate transfer belt 25 is wound around a drive roll 27, a tension roll 24, and a backup roll 28 with a constant tension, and has a constant speed (not shown). By a drive roll 27 that is rotated by a dedicated drive motor having excellent properties, it is circularly driven at a predetermined speed in the arrow direction. In FIG. 1, the intermediate transfer belt 25 includes a drive roll 27 and a tension roll 2.
4a and the backup roll 28, as well as the case of being supported by four rolls including the idler roll 24b. The intermediate transfer belt 25 is, for example, a belt material (rubber or resin) that does not cause charge-up.
The one whose resistance is adjusted is used.

Yellow (Y), magenta (M), cyan (C), which are transferred in multiple layers on the intermediate transfer belt 25,
As shown in FIG. 2, the toner image of each color of black (K) is used as a recording medium by a pressure contact force and an electric field by a secondary transfer roll 29 which is in pressure contact with a backup roll 28 arranged on the side surface of the intermediate transfer belt 25. The recording paper 30 secondarily transferred onto the recording paper 30 and having the toner images of the respective colors transferred thereto is conveyed to the fixing device 31 located above. The secondary transfer roll 29 is in pressure contact with the side of the backup roll 28, and secondarily transfers the toner image of each color onto the recording paper 30 that is conveyed from the lower side to the upper side in the vertical direction. . Then, the recording paper 30 on which the toner images of the respective colors have been transferred is subjected to a fixing process by heat and pressure by a fixing device 31, and then discharged onto a discharge tray 33 provided on the upper portion of the main body 1 by a discharge roll 32. It

As shown in FIGS. 2 and 3, the recording paper 30 is of a predetermined size from the paper feeding device 34 disposed inside the main body 1 of the apparatus, and is separated and conveyed by the najar roll 35 and the paper. The feed roll 36 for paper feeds the paper one by one in a separated state to the registration roll 38 provided in the paper feed path 37, and stops. The conveyance path 37 of the fed recording paper 30 is directed vertically upward. Recording paper 30 supplied from the paper supply device 34
Is sent to the secondary transfer position of the intermediate transfer belt 35 by the registration roll 38 which rotates at a predetermined timing.

In the above digital color printer and copying machine, when making a double-sided copy such as full color, the recording paper 30 having the image fixed on one side is not directly discharged onto the discharge tray 33 by the discharge roll 32. Then, the conveyance direction is switched by a switching gate (not shown), and the sheet is conveyed to the double-sided conveyance unit 40 via the roller pair 39 for conveying the sheet. Then, in the double-sided transport unit 40, a pair of transport rollers (not shown) provided along the transport path 41 transports the recording paper 30 to the registration roll 38 again with the front and back sides thereof reversed.
This time, the image is transferred and fixed on the back surface of the recording paper 30, and then discharged onto the discharge tray 33.

2 and 3, 44Y, 44M, 44
C and 44K denote toner cartridges that supply toner of a predetermined color to the developing devices 17 for the respective colors of yellow (Y), magenta (M), cyan (C), and black (K).

FIG. 4 shows each image forming unit of the digital color printer and the copying machine.

The four image forming units 13Y, 13M and 13 for yellow, magenta, cyan and black are formed.
As shown in FIG. 4, all of C and 13K have the same structure, and these four image forming units 13Y and
In 13M, 13C, and 13K, as described above, the yellow, magenta, cyan, and black toner images are sequentially formed at predetermined timings. The image forming units 13Y, 13M,
13C and 13K are the photosensitive drums 15 as described above.
The surfaces of these photosensitive drums 15 are uniformly charged by the charging roll 16 for charging. Then, the surface of the photoconductor drum 15 emits the laser beam LB for image formation emitted from the ROS 14 according to the image data.
Is scanned and exposed to form an electrostatic latent image corresponding to each color. The laser beam LB that is scanned and exposed on the photoconductor drum 15 is set so as to be exposed from an obliquely lower side slightly to the right of the photoconductor drum 15. The electrostatic latent image formed on the photosensitive drum 15 is the developing device 1 of each image forming unit 13Y, 13M, 13C, 13K.
No. 7 developing roller 17a develops visible toner images with yellow, magenta, cyan, and black toners, respectively, and these visible toner images are transferred onto the intermediate transfer belt 25 by charging the primary transfer roller 26. Transferred in multiple layers in sequence.

The surface of the photosensitive drum 15 after the toner image transfer step is completed is cleaned by the cleaning device 18 to remove residual toner and the like, and the surface is prepared for the next image forming process. The cleaning device 18 includes a cleaning blade 42, and the cleaning blade 42 removes residual toner and the like on the photosensitive drum 15. Also, as shown in FIGS. 2 and 3, the surface of the intermediate transfer belt 25 after the toner image transfer process is completed is cleaned by a cleaning device 43 to remove residual toner, paper dust, and the like, and the next image forming process is performed. Prepare for The cleaning device 43 includes a cleaning brush 43a and a cleaning blade 43b. The cleaning brush 43a and the blade 4 are provided.
2, the residual toner, paper dust, etc. on the intermediate transfer belt 25 are removed.

By the way, in this embodiment, a charging member for contacting the surface of the image bearing member to charge the surface of the image bearing member while rotating, and a cleaning member capable of contact and separation for cleaning the surface of the charging member. In the image forming apparatus including the above, the control unit that controls the rotation speed of the charging member during the cleaning operation to be different from that during the image formation is configured.

Further, in this embodiment, the rotation speed of the charging member during the cleaning operation is variable.

That is, as shown in FIG. 5, the charging device 50 according to this embodiment is a charging roller that contacts the surface of the photosensitive drum 15 and charges the surface of the photosensitive drum 15 to a predetermined potential. 16 and a housing member 51 that substantially covers one side surface and the lower end surface of the charging roller 16. As shown in FIG. 6, the housing member 51 includes a side wall portion 52 that covers one side surface of the charging roller 16,
A bearing portion 53 that is integrally provided at both ends in the longitudinal direction of the side wall portion 52 and that rotatably supports the metal shaft member 16a of the charging roller 16 and a bottom wall portion that covers the lower end surface of the charging roller 16 are provided. The cleaning member 54 also serves as a cleaning member. A bearing member 55 that rotatably supports the metallic shaft member 16a of the charging roller 16 is attached to the bearing portion 53 so as to be movable in a direction in which the photosensitive drum 15 is brought into contact with and separated from the bearing member 53. Further, the bearing member 55 is urged by a coil spring 56 attached to the bearing portion 53 in a direction of approaching the photosensitive drum 15.

As shown in FIG. 7, the cleaning member 54 has a flat plate portion 57 located below the charging roller 16.
And a side wall portion 58 that stands upright from the left end of the flat plate portion 57, and a cleaning brush 59 is provided on the substantially mountain-shaped upper surface 57a of the flat plate portion 57, as shown in FIG. It is fixed by means such as adhesion with double-sided tape. The cleaning member 54 is similar to that shown in FIG.
As shown in FIG. 8, the cleaning member 54 is attached to the bearing portion 53 of the housing member 51 so as to be rotatable around the shaft portion 60, and the cleaning member 54 has a stopper 60a provided in a part thereof. By engaging the bearing portion 53, as shown in FIG. 6, the bearing portion 53 is configured to stop in a state substantially orthogonal to the side wall portion 52. Further, the cleaning member 54, as shown in FIG.
In the state of being rotated in the counterclockwise direction, the tip end portion 54a in the width direction comes into contact with the stopper 61 provided at the lower end portion of the inner surface of the side wall portion 52 to stop.

Further, in the tandem type digital color printer and copying machine main body 1, as shown in FIGS. 1 and 10, the cleaning member 54 is rotated to be provided on the cleaning member 54. A contact / separation unit 62 for contacting or separating the cleaning brush 59, which constitutes a part, with or on the surface of the charging roller 16 at a predetermined timing.

As shown in FIGS. 1 and 12, the contacting / separating means 62 includes yellow, magenta, cyan and black image forming units 13Y, 13M, 13C and 13K.
In addition, a cam-shaped member 63 is provided below the housing member 51 of the charging device 50, and drives the cleaning member 54 in a direction of moving the cleaning member 54 toward and away from the surface of the charging roller 16. This cam-shaped member 63 is, as shown in FIG.
A shaft portion 64 formed into an elongated rod shape having a substantially circular cross section, a narrow flat plate portion 65 integrally formed on the upper surface of the shaft portion 64 along the longitudinal direction, and a double-sided tape on the flat plate portion 65. And a Mylar film (trade name) 66 which is a thin synthetic resin film-like member as an elastic member fixed by adhesion or the like. The Mylar film (trade name) 66 has a thickness of 125 μ, for example.
m is used. The Mylar film (trade name) 66 having different thicknesses is used, so that the Mylar film 66 is elastically deformed, so that a pressing force for bringing the cleaning brush 59 into contact with the surface of the charging roller 16 is applied. It can be adjusted.

The cam-shaped member 63 is shown in FIG. 14 and FIG.
, The image forming units 13Y, 13M, 1
A frame member 67 made of synthetic resin disposed below 3C and 13K is rotatably mounted around both ends of the shaft portion 64, and is provided at one end portion of the cam member 63 in the axial direction. The arm portion 68 is configured to be rotated in the arrow direction. Then, as shown in FIG. 11, the cam-shaped member 63 pushes the back surface of the cleaning member 54 by the mylar film 66 by rotating the cam-shaped member 63 by the arm portion 68, as described later. By rotating the cleaning member 54 counterclockwise in FIG. 11, the cleaning brush 59 provided on the cleaning member 54 is brought into contact with the surface of the charging roller 16. The mylar film 66 is used for the cleaning member 5
In order to prevent the cleaning member 54 from rotating insufficiently when the cleaning member 54 is rotated (especially in the central portion in the longitudinal direction), the rear surface of the cleaning member 54 has a central portion. As shown in FIG. 11, a plurality of ribs 69 are provided so as to project.

In addition, as shown in FIGS. 12 and 14 to 16, the main body 1 of the digital color printer and the copying machine includes yellow (Y), magenta (M), cyan (C), and black (K). Image forming units 13Y and 1 for each color
Image exposure device (ROS14) for 3M, 13C, 13K
A shutter member 70 that opens and closes the optical path is provided. This shutter member 70, as shown in FIG.
A frame member 67 made of synthetic resin disposed below each of the image forming units 13Y, 13M, 13C, and 13K is rotatably attached about a shaft portion 71 shown in FIG. It is configured to be opened / closed in the direction of the arrow by an arm member 72 formed of a plate-like elastic member made of synthetic resin or the like provided at one end of the. Further, the shutter member 70 is normally urged in the clockwise direction (closing direction) by an urging member 73 formed of a coil spring or the like, as shown in FIG.
With the film-like member 74 attached to the tip of the shutter member 70 in contact with the housing of the developing device 17, the optical path of the image exposure device 14 is blocked, and dust such as toner falling from above causes the image exposure device 14 to fall. It is designed to prevent the adherence to 14.

Further, as shown in FIGS. 1, 11 and 12, the main body 1 of the digital color printer and the copying machine includes yellow (Y), magenta (M), cyan (C) and black (K). Image forming units 13Y and 1 for each color
3M, 13C, 13K, contact and separation means 6 on the front side thereof
Two drive mechanisms 74 are provided.

As shown in FIGS. 1, 11 and 12, the drive mechanism 74 includes image forming units 13Y, 13M, and
A drive motor 75 including a pulse motor or the like as a drive source is provided on the front side of 13C and 13K and on the side of the black image forming unit 13K. The drive gear 76 of the drive motor 75 includes a two-stage reduction gear 7
A fan-shaped gear 80 integrally provided on the lower end portion of the arm member 79 is meshed with each other via 7, 78. The arm member 79 is swingable in the direction of the arrow by rotating the drive motor 75 by a predetermined amount.

Further, at the tip of the arm member 79,
As shown in FIG. 12 and the like, an operating rod 81 made of sheet metal formed in a bent state into a predetermined shape is connected. As shown in FIGS. 16 and 17, the operating rod 81 has a horizontal plate portion 83 connected to the arm member 79 by the first cutout portion 82 and a state in which the horizontal rod portion 83 is inclined obliquely downward. A short inclined plate portion 84 provided,
The connecting plate portion 8 horizontally provided at the end of the inclined plate portion 84.
5 and a short operating plate portion 86 provided in a state of being inclined obliquely upward from the connecting plate portion 85 as one set,
The three image forming units are continuously formed. Further, each horizontal plate portion 8 of the operating rod 81
A second cutout portion 87 for driving the shutter member 70 is formed at a predetermined position in the third member 3. As shown in FIG. 1 and the like, the arm member 79 is configured to directly push the arm portion 68 of the cam-like member 63 provided in the black (K) image forming unit 13K by the protrusion 79a. ing.

As shown in FIG. 16 and the like, the operating rod 81 has a second notch portion provided in each horizontal plate portion 83 in a state where the operating rod 81 has moved to the left in the figure by a predetermined amount. By the edge of 87, the shutter member 70 is rotated counterclockwise through the plate member 72 for operation provided at the end portion of the shutter member 70 to open the exposure section. . In addition, the operating rod 8
As shown in FIG. 16 and the like, when the actuating rod 81 moves rightward in the figure by a predetermined amount, the shutter member 70 is provided with an edge of the second cutout portion 87 provided in each horizontal plate portion 83. Plate-like member 7 for operation provided at the end of the
2 is released, and the shutter member 70 is
It is rotated clockwise by the biasing force of the spring 73 to close the exposure section.

Further, as shown in FIG. 16 and the like, when the operating rod 81 moves further rightward in the figure by a predetermined amount, the operating plate portion 86 causes the operating plate portion 86 to move in the cam-shaped member 63.
The arm portion 68 provided at the axial end portion of is pushed to rotate the cam-shaped member 63 in the counterclockwise direction by a predetermined amount. Therefore, the cam-shaped member 63
With the mylar film 66 of, as shown in FIG.
The cleaning member 54 of the charging roller 16 is rotated,
A cleaning brush 59 provided on the cleaning member 54 contacts the surface of the charging roller 16.

By the way, in this embodiment, as described above, the rotation speed of the charging member during the cleaning operation is
It is configured so as to include a control unit that controls the image formation process to be different from that during image formation.

Further, in this embodiment, the rotation speed of the charging member during the cleaning operation is variable.

FIG. 1 is a block diagram showing the control unit of the printer and the copying machine according to the first embodiment together with the image forming unit.

In FIG. 1, reference numeral 600 is a control circuit as a control means including a CPU for controlling the operation of the image forming apparatus, and 610 is the number of pixels (pixel number) of the image formed by the image forming apparatus. A counter circuit 620 for counting the number of rotations of the photosensitive drum 15, and a cleaning circuit 630 for cleaning each time the count value of the counter circuit 61 reaches a predetermined value. Drive motor 75 for driving the member 45
Is operated to bring the cleaning member 54 into contact with and separate from the surface of the charging roll 16 for a certain time, and 640 is a process speed variable circuit for varying the process speed.

Here, for the sake of convenience, the counting circuit 610 for counting the number of pixels of the image formed by the image forming apparatus based on the image data has been described as one circuit, but the counting circuit 610 is controlled by the control circuit. Of course, it may be constituted by a software counter executed by the circuit 600. In this case, the count value of the software counter executed by the control circuit 600 is stored in a storage circuit such as a RAM (not shown) at any time. Then, every time an image is formed by the image forming apparatus, the count value of the number of pixels of the image is integrated as the count value of the software counter. Further, the photoconductor rotation number counting circuit 630 may be similarly configured. ,

In the case of the tandem type digital color printer and the copying machine according to the present embodiment having the above-mentioned constitutions, the degree to which the surface of the charging roller is contaminated with the toner or the external additive is determined as follows. By controlling the conditions for cleaning the surface of the charging roller according to the image forming conditions, the surface of the charging roller is not excessively worn or scratched, and the surface of the charging roller is sufficiently cleaned. It is possible to prevent deterioration of image quality due to poor charging or uneven charging.

That is, in the case of the tandem type digital color printer and the copying machine according to this embodiment,
As shown in FIGS. 2 to 4, each image forming unit 13
Yellow (Y), magenta (M), cyan (C), and black (K) toner images are sequentially formed by Y, 13M, 13C, and 13K in accordance with the image data. , 13M, 1
The toner images of yellow (Y), magenta (M), cyan (C), and black (K) formed by 3C and 13K are primary-transferred on the intermediate transfer belt 35 in multiple layers, and then the recording paper 30 Secondly transferred onto the recording sheet 3
The toner images of the respective colors are fixed on the image forming unit 0 to form a full-color image or a single-color image.

At this time, in the image forming apparatus, as shown in FIG. 18A, for example, when a monochrome monochromatic image is formed, the photosensitive drum 15K is rotationally driven at a process speed of 194 mm / sec. At the same time, the charging roller 16 is driven to rotate while being in contact with the surface of the photosensitive drum 15, and at a predetermined timing prior to the printing operation, the cleaning brush 59 of the cleaning member 54.
Is brought into contact with the surface of the charging roller 16 to clean the surface of the charging roller 16. At that time, as shown in FIG. 18B, the cleaning brush 59 is brought into contact with the surface of the charging roller 16 by further rotating the drive motor 75 in the closing direction with the shutter member 70 closed. . At this time, even if the process speed at the time of image formation is set to 194 mm / sec as shown in FIG. 18A, the process speed variable circuit 640 is used during the cleaning operation. The process speed is set to 104 mm / sec, which is slower than that during image formation. As a result, the photoconductor drum 15K is rotationally driven at a process speed of 104 mm / sec, and the charging roller 16 is also driven to rotate while being in contact with the surface of the photoconductor drum 15K.
It is rotationally driven at mm / sec.

As described above, in the first embodiment, during the cleaning operation, the process speed changing circuit 640 changes the process speed to 104 mm / sec, which is slower than that during image formation. As in the case of driven rotation at a high process speed, the relative speed difference between the cleaning brush member 54 and the cleaning brush 59 becomes too large, and the abrasion of the surface of the charging roller 16 is promoted, or scratches are generated. Can be prevented. Further, since the charging roller 16 is rotated at a speed sufficient for cleaning, the surface of the charging roller 16 is sufficiently cleaned to prevent deterioration of image quality due to poor charging or uneven charging. be able to.

In the above first embodiment, for example,
The explanation has been given for the case of changing the process speed during cleaning operation to a slower speed than that during image formation when forming a monochrome monochrome image.However, when forming a full-color image, the process speed during cleaning operation can be changed. ,
The speed may be changed to be slower than that during image formation.

Embodiment 1-2 In this Embodiment 1-2, a control means for varying the cleaning time by the cleaning member according to the process speed is provided.

That is, in this Embodiment 1-2, as shown in FIG. 19, when the process speed is 194 mm / sec, the cleaning time T is set to 33.6 sec and the process speed is changed by the process speed variable circuit 640. Is 104 mm / sec, the cleaning time T can be halved to 16.8 sec, and when the process speed is 52 mm / sec, the cleaning time T can be further halved to 8.4 sec. It is configured to do.

Here, the process speed is 194
In the case of mm / sec, when forming a monochrome monochrome image, when the process speed is 104 mm / sec, when forming a full color image on plain paper, when the process speed is 52 mm / sec, These are set when forming a full-color image on an OHP sheet or thick paper.

As described above, by varying the cleaning time by the cleaning member 54 according to the process speed, the process speed is 194 mm / sec.
In the case of such a high speed, the photosensitive drum 15K and the charging roller 16 are also rotationally driven at a high rotational speed, so that the amount of the toner image developed on the photosensitive drum 15K also increases.
Since the amount of toner and external additives that adhere to the surfaces of the photoconductor drum 15K and the charging roller 16 also increases accordingly, the cleaning time increases as the process speed increases, depending on the process speed. By setting, it is possible to sufficiently clean the surface of the charging roller 16 and prevent deterioration of image quality due to poor charging or uneven charging.

As described in Embodiment 1-1, if the cleaning operation is performed at the same process speed when the process speed is as high as 194 mm / sec, the abrasion of the surface of the charging roller 16 is accelerated. It is desirable that the process speed changing circuit 640 changes the process speed to a speed slower than that at the time of image formation during the cleaning operation because there is a risk of damage or damage.

Second Embodiment FIG. 20 shows a second embodiment of the present invention. The same parts as those in the first embodiment will be designated by the same reference numerals. The rotational speed of the charging member during the cleaning operation is variable.

That is, in the second embodiment, FIG.
As shown in, the charging roller 16 is not pressed against the surface of the photosensitive drum 15 and is not driven to rotate by frictional force, but the charging roller 16 is rotationally driven by an original driving source (not shown), or The rotation speed of the charging roller 16 during the cleaning operation can be varied in two stages (plural stages), for example, by providing two sets (plural sets) of transmission gears for transmitting the driving force and switching by a clutch. Has become.

In the second embodiment, for example, when the process speed is 104 mm / sec, the charging roller 16 is rotationally driven at 90 mm / sec or 120 mm / sec. The charging roller 16 is decelerated to 90 mm / sec and rotationally driven, or 120 m
Whether or not the rotational speed is increased to m / sec may be appropriately set in consideration of the state in which the charging roller 16 is contaminated. The process speed is 194 mm / sec
Also in the case of or 52 mm / sec, the rotation speed of the charging roller 16 may be decelerated or increased to be rotationally driven.

By making the rotation speed of the charging roller variable during the cleaning operation as described above, a sufficient cleaning effect can be obtained on the charging roller during the cleaning operation, and further, the abrasion of the surface of the charging roller 16 can be promoted. It can be rotated at a speed that can prevent the occurrence of scratches and scratches.

The other structure and operation are the same as those in the first embodiment, and the description thereof will be omitted.

Embodiment 3 FIG. 21 shows Embodiment 3 of the present invention. The same parts as those in Embodiment 1 are designated by the same reference numerals and explained. A use time detecting means for detecting a use time of the charging member is provided, and the cleaning condition is controlled according to a detection result of the use time detecting means.

That is, in the third embodiment, FIG.
As shown in FIG. 6, the cumulative number of printed sheets is counted by a printed sheet number counting circuit as a used time detecting means for detecting the used time of the charging member.
When the number of sheets reaches 00, the cleaning condition is, for example, a cleaning time of 8.4 sec, and when the cumulative number of printed sheets reaches 5,000, the cleaning condition is, for example, double the cleaning time 16. 8s
It is configured to switch to ec.

The cleaning time may be linearly increased each time the cumulative number of prints increases by 2,500, or when the cumulative number of prints exceeds a predetermined value, the cleaning time is increased at a higher rate. May be set to increase.

The other structure and operation are the same as those of the first embodiment, and therefore the description thereof is omitted.

Fourth Embodiment FIG. 22 shows a fourth embodiment of the present invention. The same parts as those of the first embodiment will be designated by the same reference numerals. During the cleaning operation, the rotational speeds of the image carrier and the charging member are controlled to be increased.

That is, in the fourth embodiment, as shown in FIG.
As shown in FIG. 1, unlike the first embodiment, the photosensitive drum 15 is set at a process speed of 104 mm /
When the charging roller 16 is driven to rotate at the same process speed, the photosensitive drum 15 is rotated at a process speed of 194 mm /
It is configured to be rotationally driven in sec, and the charging roller 16 is quickly driven to rotate at the same process speed.

As described above, by controlling the rotational speeds of the photoconductor drum 15 and the charging roller 16 to be increased during the cleaning operation, the cleaning property of the cleaning brush can be improved during the cleaning operation, and the charging can be performed. By sufficiently cleaning the surface of the roller 16, it is possible to reliably prevent the deterioration of the image quality due to the charging failure or the uneven charging.

Incidentally, simply during the cleaning operation,
If the rotational speeds of the photoconductor drum 15 and the charging roller 16 are controlled to be increased, the abrasion of the surface of the charging roller 16 may be promoted, and scratches may occur. Can be set shorter,
Only after the cumulative number of prints reaches a predetermined value, the rotational speeds of the photosensitive drum 15 and the charging roller 16 may be controlled to be increased during the cleaning operation.

The other structure and operation are the same as those of the first embodiment, and therefore the description thereof is omitted.

Fifth Embodiment FIG. 23 shows a fifth embodiment of the present invention. The same parts as those in the first embodiment will be designated by the same reference numerals and will be described. During the cleaning operation, the speed at which the cleaning member is brought into contact with the surface of the charging member is variable.

That is, in this fifth embodiment, FIG.
1, the drive motor is rotationally driven to rotate the cleaning member 54 in the counterclockwise direction in FIG. 1, and the cleaning brush 59 provided on the cleaning member 54 is brought into contact with the surface of the charging roller 16. When the cleaning brush 59 is moved to the charging roller 16 side instead of rotating the driving motor 75 including a pulse motor at a constant speed, the driving motor is rotated at a relatively high speed. When the cleaning brush 59 is driven to come into contact with the surface of the charging roller 16 and a predetermined contact state is achieved, the driving speed is gradually changed to be slow, and the cleaning brush 59 is brought into contact with the surface of the charging roller 16 by a predetermined amount. It is configured to stop when it comes into contact.

As described above, during the cleaning operation, the speed at which the cleaning brush 59 is brought into contact with the surface of the charging roller 16 is variable, and the cleaning brush 59 is set to be gradually slowed down so that the cleaning brush 59 can be charged. Since the rotation speed of the drive motor 75 gradually decreases until it comes into contact with the surface of the drive motor to reach a predetermined contact state, the rotation torque of the drive motor 75 can be increased correspondingly, and the cleaning brush 59 can be used. The contact state of the drive motor 7 can be realized in a short time in total and with a relatively weak force of the drive motor 75.
5 can be miniaturized, and sufficient cleaning performance can be ensured, and the cost can be reduced accordingly.

The other structure and operation are the same as those in the first embodiment, and the description thereof will be omitted.

Embodiment 6-1 FIG. 24 shows a sixth embodiment of the present invention. The same parts as those of the first embodiment will be designated by the same reference numerals and will be described below. In No. 6, the pressing force when the cleaning member is brought into contact with the surface of the charging member is made variable according to the process speed.

That is, in this Embodiment 6-1, as shown in FIG. 24, the pressing force for bringing the cleaning member 54 into contact with the surface of the charging roller 16 is 1 when the process speed is 52 mm / sec. 0.0 kgf, 1.3 kg when the process speed is 104 mm / sec
It is configured to be variable according to the process speed, such as 1.5 kgf when the process speed is 194 mm / sec.

As described above, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is variable according to the process speed, so that the process speed is 52 mm / sec. When the speed is slow, the surface of the charging roller 16 is less contaminated. Therefore, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is set weak, and the process speed is 104 mm / sec or 194 mm / sec. Since the dirt on the surface of the charging roller gradually increases as the speed becomes relatively faster, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is set to be stronger accordingly. It is sufficient to prevent abrasion of the surface of the charging roller 16 and prevent scratches from occurring. It is possible to obtain the cleaning properties.

As a means for varying the pressing force when the cleaning member 545 is brought into contact with the surface of the charging roller 16, the drive time of the drive motor 75 for driving the cleaning member 54 is controlled, and the mylar film 66 is controlled. Means for changing the amount of elastic deformation of

Embodiment 6-2 FIG. 25 shows an embodiment 6-2 of the present invention. The same parts as those of the embodiment 1 will be designated by the same reference numerals and will be described below. 6-2, the pressing force when the cleaning member is brought into contact with the surface of the charging member is
It is configured to be variable according to the number of pixels on which an image is formed.

That is, in this Embodiment 6-2, as shown in FIG. 25, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is determined by the number of pixels (number of pixels) on which image formation is performed. ) Is 1.0k up to 100k
gf, 1.3kgf up to 300k pixels,
It is configured to be variable according to the number of pixels on which an image is formed, such as 1.5 kgf up to 500 k.

As described above, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is made variable according to the number of pixels on which the image is formed, and thus the number of pixels on which the image is formed. If there are few,
Since the surface of the charging roller 16 is also less contaminated, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is set weak, and the surface of the charging roller 16 becomes dirty as the number of pixels on which the image is formed increases. Therefore, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is set to be strong accordingly, so that the charging roller 16
Sufficient cleaning properties can be obtained while preventing abrasion of the surface and preventing scratches.

Embodiment 6-3 FIG. 26 shows an embodiment 6-3 of the present invention. The same parts as those of the embodiment 1 will be designated by the same reference numerals and will be described below. In the form 6-3, the pressing force when the cleaning member is brought into contact with the surface of the charging member is
It is configured to be variable according to the cumulative number of image formations.

That is, in this Embodiment 6-3, as shown in FIG. 26, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is 1 when the number of image formations (print volume PV) is 1. Up to 1,000 sheets are 1.
0 kgf, print volume PV up to 2,500 sheets 1.3 kgf, print volume PV 5,0
It is configured to be variable in accordance with the number of image forming sheets, such as 1.5 kgf up to 00 sheets.

As described above, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is made variable according to the accumulated number of image formations. Since the surface of the roller 16 is less contaminated, the pressing force for bringing the cleaning member 54 into contact with the surface of the charging roller 16 is set to be weak, and as the number of accumulated image formations increases, the charging roller 1
Since the surface of the charging roller 16 gradually becomes dirty, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is set to be strong accordingly, so that the abrasion of the surface of the charging roller 16 is promoted. It is possible to obtain sufficient cleaning property while preventing the occurrence of scratches and scratches.

Embodiment 6-4 FIG. 27 shows an embodiment 6-4 of the present invention. The same parts as those of the embodiment 1 are designated by the same reference numerals and explained. In Embodiment 6-4, the pressing force when the cleaning member is brought into contact with the surface of the charging member is
It is configured to be variable according to the accumulated number of rotations of the image carrier.

That is, in this Embodiment 6-4, as shown in FIG. 27, the pressing force at the time when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is the cumulative number of rotations of the photosensitive drum 15. 1.0kgf up to 10k,
When the accumulated number of rotations of the photosensitive drum 15 is up to 25k, 1.
3 kgf, the accumulated number of rotations of the photosensitive drum is 1.5 kgf up to 50 k, and is variable according to the accumulated number of rotations of the photosensitive drum 15.

As described above, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is made variable in accordance with the accumulated number of rotations of the photosensitive drum 15, so that the accumulated photosensitive drums. When the rotation speed of 15 is small, the surface of the charging roller 16 is also less contaminated. Therefore, the pressing force when the cleaning member 54 is brought into contact with the surface of the charging roller 16 is set to be weak, and the accumulated photosensitive drum 1
As the number of rotations of 5 increases, the dirt on the surface of the charging roller gradually increases. Therefore, the pressing force for bringing the cleaning member 54 into contact with the surface of the charging roller 16 should be set to be stronger accordingly. As a result, it is possible to obtain sufficient cleaning properties while preventing abrasion of the surface of the charging roller 16 and preventing scratches and the like from occurring.

The other structure and operation are the same as those in the first embodiment, and the description thereof will be omitted.

Seventh Embodiment FIG. 28 shows a seventh embodiment of the present invention. The same parts as those of the first embodiment will be designated by the same reference numerals and will be described. Then, the operation of bringing the cleaning member into and out of contact is different from that in the above embodiment.

That is, in the embodiment shown in FIG. 28A, the contacting / separating operation is performed a plurality of times during one cleaning cycle.

With this configuration, the cleaning brush 5 can be used during one cleaning cycle.
The cleaning efficiency can be improved as compared with the case where 9 is kept in contact with the surface of the charging roller 16.

In the embodiment shown in FIG. 28B, the cleaning operation different from other cleaning operations is performed at least once.

Here, the cleaning operation different from the other cleaning operations is, for example, the cleaning brush 59.
Means an operation in which the time of contact with the surface of the charging roller 16 is different.

In the embodiment shown in FIG. 28C, a cleaning operation different from other cleaning operations means a cleaning operation having an operating torque different from that of other cleaning operations at least once.

Further, in the embodiment shown in FIG. 28 (d), the cleaning member is always moved while performing the contacting / separating operation once or plural times during one cleaning cycle. .

Furthermore, in the embodiment shown in FIG. 28E, when the cleaning member is separated from the charging member, the cleaning member comes into contact with the charging member for at least one round of the charging member. It is configured to

The other structure and operation are the same as those of the first embodiment, and the description thereof will be omitted.

[0122]

As described above, according to the present invention,
Depending on the image forming conditions that determine the extent to which the surface of the charging roller is contaminated with toner, external additives, etc., by controlling the conditions for cleaning the surface of the charging roller, the surface of the charging roller is excessively worn, It is possible to provide an image forming apparatus that is not scratched and that is capable of sufficiently cleaning the surface of the charging roller and preventing deterioration of image quality due to poor charging or uneven charging.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing essential parts of a digital color printer and a copying machine as an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a digital color printer as an image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a digital color copying machine as an image forming apparatus to which the sheet feeding device according to the first embodiment of the present invention is applied.

FIG. 4 is a configuration diagram showing an image forming unit of the image forming apparatus according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing a charging roll of the image forming apparatus according to the first embodiment of the present invention.

FIG. 6 is a perspective view showing a housing of a charging roll of the image forming apparatus according to the first embodiment of the present invention.

FIG. 7 is a perspective view showing a cleaning member of the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 8 is a perspective view showing a cleaning member of the image forming apparatus according to the first embodiment of the present invention.

FIG. 9 is a perspective view showing a housing of a charging roll of the image forming apparatus according to the first embodiment of the present invention.

FIG. 10 is a perspective view showing a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 11 is a front view showing a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 12 is a perspective view showing a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 13 is a perspective view showing a cam-shaped member of the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 14 is a perspective view showing a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 15 is a perspective view showing a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 16 is a perspective view showing a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 17 is a perspective view showing an operating rod.

FIG. 18 is a timing chart showing an operation of the image forming apparatus according to the embodiment 1-1 of the present invention.

FIG. 19 is a graph showing an operation of the image forming apparatus according to the embodiment 1-2 of the present invention.

FIG. 20 is a configuration diagram showing an image forming apparatus according to a second embodiment of the present invention.

FIG. 21 is an explanatory diagram showing an operation of the image forming apparatus according to the third embodiment of the present invention.

FIG. 22 is a timing chart showing an operation of the image forming apparatus according to the fourth embodiment of the present invention.

FIG. 23 is an explanatory diagram showing the operation of the image forming apparatus according to the fifth embodiment of the present invention.

FIG. 24 is a graph showing an operation of the image forming apparatus according to the embodiment 6-1 of the present invention.

FIG. 25 is a graph showing an operation of the image forming apparatus according to Embodiment 6-2 of the present invention.

FIG. 26 is a graph showing an operation of the image forming apparatus according to Embodiment 6-3 of the present invention.

FIG. 27 is a graph showing the operation of the image forming apparatus according to Embodiment 6-4 of the present invention.

FIG. 28 is a timing chart showing the operation of the image forming apparatus according to the seventh embodiment of the present invention.

FIG. 29 is a block diagram showing a conventional image forming apparatus.

[Explanation of symbols]

1: Digital color printer body, 13Y, 13M,
13C and 13K: image forming units of yellow (Y), magenta (M), cyan (C), and black (K), 1
4: ROS, 15: photoconductor drum, 16: charging roller, 54: cleaning member, 59: cleaning brush, 62: contacting / separating means, 63: cam member, 66: thin synthetic resin film as elastic member Member, 600:
Control circuit, 630: contact / separation circuit, 640: variable process speed circuit.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masanori Kato             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. (72) Inventor Tomokazu Kurita             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. F term (reference) 2H200 FA09 GA12 GA23 GA34 HA01                       HA28 HB12 LA06 LA18 LA20                       LA24 LB02 LB09 LB12 LB39                       LB40 PA10 PA11 PA12 PA14                       PB14 PB33 PB35

Claims (16)

[Claims] 1. An image forming apparatus comprising: a charging member that charges the surface of the image bearing member while rotating while contacting with the surface of the image bearing member; An image forming apparatus, comprising: a control unit that controls a rotation speed of a charging member during a cleaning operation to be different from that during image formation. 2. An image forming apparatus comprising: a charging member for charging the surface of the image carrier while rotating while contacting with the surface of the image carrier; and a contactable / separable cleaning member for cleaning the surface of the charging member. An image forming apparatus, comprising: a control unit that varies a cleaning time by the cleaning member according to a process speed. 3. An image forming apparatus comprising: a charging member that charges the surface of the image bearing member while rotating while contacting with the surface of the image bearing member; In the apparatus, the rotation speed of the charging member at the time of cleaning operation is controlled to be different from that at the time of image formation, and the cleaning time by the cleaning member is varied according to the process speed. Forming equipment. 4. The image forming apparatus according to claim 1, wherein the rotational speed of the charging member during the cleaning operation is variable. 5. The image forming apparatus according to claim 1, further comprising a usage time detection unit that detects a usage time of the charging member, and performs cleaning according to a detection result of the usage time detection unit. An image forming apparatus characterized by controlling conditions. 6. The image forming apparatus according to claim 1, wherein the rotational speed of the image carrier and the charging member is controlled to be increased during a cleaning operation. apparatus. 7. The image forming apparatus according to claim 1, wherein the speed at which the cleaning member is brought into contact with the surface of the charging member is variable during the cleaning operation. Image forming apparatus. 8. The image forming apparatus according to claim 1, wherein the pressing force for bringing the cleaning member into contact with the surface of the charging member is variable according to the process speed. A characteristic image forming apparatus. 9. The image forming apparatus according to claim 1, wherein the pressing force for bringing the cleaning member into contact with the surface of the charging member is variable according to the number of pixels on which image formation is performed. An image forming apparatus characterized in that it is possible. 10. The image forming apparatus according to claim 1, wherein the pressing force when the cleaning member is brought into contact with the surface of the charging member can be changed according to the number of accumulated image formations. An image forming apparatus characterized by the above. 11. The image forming apparatus according to claim 1, wherein the pressing force when the cleaning member is brought into contact with the surface of the charging member depends on the accumulated number of rotations of the image carrier. An image forming apparatus which is variable. 12. The image forming apparatus according to claim 1, wherein the contacting / separating operation is performed a plurality of times during one cleaning cycle. 13. The image forming apparatus according to claim 12, wherein a cleaning operation different from other cleaning operations is performed at least once. 14. The image forming apparatus according to claim 12, wherein a cleaning operation having an operation torque different from that of other cleaning operations is performed at least once. 15. The image forming apparatus according to claim 1, wherein the cleaning member is always moving while performing one or more contacting / separating operations during one cleaning cycle. A characteristic image forming apparatus. 16. The image forming apparatus according to claim 1, wherein when the cleaning member is separated from the charging member, the cleaning member serves as the charging member for at least one round of the charging member. An image forming apparatus characterized by being in contact.