JP2008298883A - Image forming apparatus, image holder, and image holder unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect the surface of a photoreceptor from external light with a simple configuration. <P>SOLUTION: An image forming apparatus (U) includes: cleaners (CLy-CLk) for cleaning image holders (Py-Pk) by removing shading layers (1, 4, 11, 21) of the surface of the image holders (Py-Pk) covering an exposure face exposed to the outside by the shading layers (1, 4, 11, 21) comprising a shading material (3); development units (GY-GK, Gy-Gk) for developing latent images on visual images formed by latent image forming apparatuses (ROSy-ROSk) on the surface of the image holders (Py-Pk) charged with charging units (CCy-CCk, CRy-CRk) for charging the surface of the image holders (Py-Pk) removing the shading layers (1, 4, 11, 21); and transfer units (T1y-T1k) for transferring the visual images of the image holders (Py-Pk) on a medium. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image carrier that holds a toner image on the surface and an image forming apparatus that includes an image carrier unit.

In a conventional electrophotographic image forming apparatus, a photoreceptor is generally used as an image carrier. The photosensitive member has a photosensitive layer on the surface, and when the photosensitive member is irradiated with light, charges are generated and transported. Therefore, when the photosensitive member is exposed to external light, light fatigue may occur in the portion exposed to the external light, and an image omission or density difference may occur in the printed image. In addition, since the photoconductor deteriorates with time due to discharge by a charger or transfer device or surface wear by a cleaner, the image carrier unit is often configured to be detachable and replaceable. Light fatigue due to exposure of the photoreceptor to light is also a problem. Further, when the cover of the image forming apparatus is opened due to a paper jam, toner cartridge replacement or developing device replacement, the internal photoreceptor surface may be exposed to light.
In order to cope with these problems, techniques described in Patent Documents 1 and 2 are known as techniques for providing a cover for preventing the photosensitive member from being exposed to light.

(J01) Technology described in Patent Document 1 (Japanese Patent Laid-Open No. 8-30076) In Patent Document 1, a cover (46) is provided so as to cover the optical device (22) that exposes the photosensitive drum (1). The shutter (52) that can be opened and closed of the second slit (50) through which the reflected light from the document D provided on the cover (46) enters is controlled to be opened and closed except during image formation. A technique for preventing light from entering the device (22) is described. In the technique described in Patent Document 1, since the shutter (52) is opened during the image forming operation, the second slit (50) is opened, and the reflected light from the exposed original D is passed to the photoreceptor (20) side. In addition, since the shutter (52) is shielded at the end of the image forming operation, the light incident on the optical device (22) is shielded to protect the surface of the photoreceptor (20) from external light.
(J02) Technology described in Patent Document 2 (Japanese Patent Laid-Open No. 4-172486) In Patent Document 2, the photosensitive drum (1) is protected by a film sheet (B-1) formed of a flexible sheet. A technique for shading is known. In the technique disclosed in Patent Document 2, when the process cartridge (B) having the photosensitive drum (1) is mounted in the image forming apparatus, the photosensitive drum (1) is opened on the film sheet (B-1). The film sheet (B-1) is moved to an open position where it can be used, and when the process cartridge (B) is not mounted in the image forming apparatus, the photosensitive drum (1) is protected from external light and can be shielded from light. The photosensitive drum (1) is protected from external light.

Further, as a technique for correcting the parameter relating to image formation in accordance with the deterioration of the surface of the photoreceptor, the technique of Patent Document 3 is described as a technique for dealing with the above problem.
(J03) Technology described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2000-347545) Patent Document 3 describes that the exposure unit (3) is provided during one rotation of the photosensitive member (1) immediately after power-on or during standby. The surface potential of the photoconductor (1) is measured by blinking, and the charging unit 2 is applied so that the measurement result is within the range of the reference value unless the measurement result is within the range of the reference value that allows normal image formation. A technique for correcting image forming parameters such as voltage and output of laser light from the exposure unit (3) is described.

JP-A-8-30076 ("0008" to "0013", "0033" to "0034", FIG. 3) JP-A-4-172486 ("0010" to "0012", "0028" to "0032") JP 2000-347545 A ("0019" to "0020", "0043" to "0054")

(Problems of conventional technology)
However, in Patent Documents 1 and 2, since a light shielding member such as a cover (46) and a shutter member is provided, the number of parts to be used increases, and there is a problem that the configuration becomes complicated.
In Patent Document 3, since there is no device or means for shielding the surface of the photoconductor from outside light, it is easily exposed to outside light, and the potential sensor (8) and the control for controlling the potential sensor (8) are controlled. Since a device or the like is required, there is a problem that the number of parts to be used increases and the configuration becomes complicated. In Patent Document 3, the image forming parameters are corrected so that normal image formation can be performed when the surface of the photoconductor is deteriorated.

In view of the above circumstances, the present invention has the following description (O01) as a technical problem.
(O01) To protect the surface of the photoreceptor from external light with a simple configuration.

Next, the present invention that solves the above problems will be described. However, in order to easily understand the correspondence between the constituent elements of the present invention and the constituent elements of the embodiments described later, it is implemented immediately after the constituent elements of the present invention. The reference numerals of the constituent elements in the example are enclosed in parentheses ().
The reason why the present invention is described in correspondence with the reference numerals of the embodiments described later is to facilitate understanding of the present invention, and does not limit the scope of the present invention to the embodiments.

(First invention)
In order to solve the above problems, the image forming apparatus (U) of the first invention is
An image carrier (Py to Pk) whose exposed surface exposed to the outside is covered by a light shielding layer (1, 4, 11, 21) made of a light shielding material (3);
A cleaner (CLy to CLk) for removing the light shielding layer (1, 4, 11, 21) on the surface of the image carrier (Py to Pk) and cleaning the image carrier (Py to Pk);
A charger (CCy to CCk, CRy to CRk) for charging the surface of the image carrier (Py to Pk) from which the light shielding layer (1, 4, 11, 21) has been removed;
A latent image forming device (ROSy to ROSK) that forms a latent image on the surface of the image carrier (Py to Pk) charged by the chargers (CCy to CCk, CRy to CRk);
Developing units (GY to GK, Gy to Gk) for developing a latent image on the surface of the image carrier (Py to Pk) into a visible image;
A transfer unit (T1y to T1k) for transferring a visible image on the surface of the image carrier (Py to Pk) to a medium;
It is provided with.

(Operation of the first invention)
In the image forming apparatus (U) of the first invention having the above-described configuration, the cleaners (CLy to CLk) are externally provided by the light shielding layers (1, 4, 11, 21) constituted by the light shielding material (3). The light-shielding layer (1, 4, 11, 21) on the surface of the image carrier (Py to Pk) covered with the exposed exposed surface is removed to clean the image carrier (Py to Pk). The latent image forming apparatuses (ROSy to ROSK) are chargers (CCy to CCk, CRy to CRk) for charging the surface of the image carrier (Py to Pk) from which the light shielding layers (1, 4, 11, 21) are removed. A latent image is formed on the surface of the image holding member (Py to Pk) charged in step S2. Developing units (GY to GK, Gy to Gk) develop the latent image on the surface of the image carrier (Py to Pk) into a visible image. The transfer units (T1y to T1k) transfer the visible image on the surface of the image carrier (Py to Pk) to a medium.
Therefore, in the image forming apparatus (U) of the first invention, the surface of the image carrier (Py to Pk) is protected from external light from the exposed surface exposed to the outside by the light shielding layers (1, 4, 11, 21). Therefore, it is not necessary to provide a light shielding member such as a shutter or a potential sensor as in the prior art, and the configuration can be simplified. Further, image formation can be performed after the light shielding layers (1, 4, 11, 21) are removed from the surface of the image carrier (Py-Pk) by the cleaners (CLy-CLk).

(First Embodiment 1)
The image forming apparatus (U) according to the first aspect of the present invention is the first aspect of the present invention.
A light shielding layer formation start discriminating means (C4a) for discriminating whether or not to start the formation of the light shielding layer (1, 4, 11, 21);
Controlling the image carrier (Py to Pk), the charger (CCy to CCk, CRy to CRk), the latent image forming device (ROSy to ROSK) and the developing unit (GY to GK, Gy to Gk) The surface of the image carrier (Py to Pk) is charged, and the surface of the charged image carrier (Py to Pk) is shaded by the latent image forming device (ROSy to ROSK) (1, 4, 11, 21). ) Forming a latent image of the forming image, and forming the light-shielding layer (1, 4, 11, 21) by visualizing the latent image with the developing units (GY to GK, Gy to Gk); A light-shielding layer formation control unit (1) which covers the exposed surface of the surface of the image carrier (Py to Pk) exposed to the outside when the inside of the image forming apparatus (U) is opened with the light-shielding layer (1, 4, 11, 21). C4)
It is provided with.

(Operation of Form 1 of the First Invention)
In the image forming apparatus (U) according to the first aspect of the first invention having the above-described configuration, the light shielding layer formation start determining means (C4a) determines whether or not to start the formation of the light shielding layers (1, 4, 11, 21). Is determined. The light shielding layer formation control means (C4) includes the image carrier (Py to Pk), the chargers (CCy to CCk, CRy to CRk), the latent image forming device (ROSy to ROSK), and the developing unit (GY). To GK, Gy to Gk) to charge the surface of the image carrier (Py to Pk), and the latent image forming device (ROSy to ROSK) on the charged surface of the image carrier (Py to Pk). To form a latent image of an image for forming a light shielding layer, and the latent image is visualized by the developing units (GY to GK, Gy to Gk) to form a light shielding layer (1, 4, 11, 21). The exposed surface of the surface of the image carrier (Py to Pk) exposed to the outside when the inside of the image forming apparatus (U) is opened is covered with the light shielding layer (1, 4, 11, 21).
Therefore, in the image forming apparatus (U) according to the first aspect of the present invention, when the input of the formation of the light shielding layers (1, 4, 11, 21) is instructed, the image forming apparatus (U) is externally opened when the inside of the image forming apparatus (U) is opened. The exposed surface of the surface of the image carrier (Py to Pk) that is exposed and may be exposed to light can be covered with a light shielding layer (1, 4, 11, 21).

(First Embodiment 2)
The image forming apparatus (U) according to the second aspect of the present invention is the first aspect of the first aspect of the present invention.
The surface set from the surface facing the developing units (GY to GK, Gy to Gk) to the surface facing the cleaning units (CLy to CLk) along the rotation direction of the image carrier (Py to Pk). An exposed surface that is set above the image carrier (Py to Pk) in the direction of gravity;
The light shielding layer formation control means (C4) for rotating the image carrier (Py to Pk) in the same rotational direction as in the image forming operation to form the light shielding layers (11, 21);
It is provided with.

(Operation of the second aspect of the first invention)
In the image forming apparatus (U) according to the second aspect of the first invention having the above-described configuration, the light shielding layer formation control means (C4) is arranged such that the image from the surface facing the developing units (GY to GK, Gy to Gk). It is the exposed surface set up to the surface facing the cleaners (CLy to CLk) along the rotation direction of the holder (Py to Pk), and the image holder (Py to Pk) in the direction of gravity. The light-shielding layers (11, 21) are formed on the exposed surface set on the upper side by rotating the image carrier (Py to Pk) in the same rotational direction as in the image forming operation.
Therefore, in the image forming apparatus (U) according to the second aspect of the first invention, the exposed surface set in the upper portion of the image carrier (Py to Pk) is protected in the direction of gravity that is often irradiated with external light. can do.

(Embodiment 3 of the first invention)
An image forming apparatus (U) according to a third aspect of the present invention is the first aspect of the first aspect of the present invention.
The surface set from the surface facing the cleaning device (CLy to CLk) to the surface facing the developing device (GY to GK, Gy to Gk) along the rotation direction of the image carrier (Py to Pk). An exposed surface that is set above the image carrier (Py to Pk) in the direction of gravity;
After the image carrier (Py to Pk) is rotated in the same rotation direction as in the image forming operation to form the light shielding layer (1, 4), the light shielding layer (1, 4) corresponds to the exposed surface. The light-shielding layer formation control means (C4) for rotating the image carrier (Py to Pk) in the direction opposite to that during the image forming operation until it moves to a position;
It is provided with.

(Operation of the third aspect of the first invention)
In the image forming apparatus (U) according to the third aspect of the present invention, the light shielding layer formation control means (C4) rotates the image carrier (Py to Pk) in the same rotational direction as that during the image forming operation, thereby blocking the light shielding. After forming the layer (1, 4), the light shielding layer (1, 4) is developed from the surface facing the cleaner (CLy to CLk) along the rotation direction of the image carrier (Py to Pk). Corresponding to the exposed surface set up to the surface facing the containers (GY to GK, Gy to Gk) and set above the image carrier (Py to Pk) in the direction of gravity. The image carrier (Py to Pk) is rotated in the direction opposite to that in the image forming operation until it moves to the position.
Therefore, the light shielding layer (1, 4) is moved to the exposed surface set in the upper portion of the image carrier (Py to Pk) in the direction of gravity, which is often irradiated with external light, and from the external light. The exposed surface can be protected.

(First aspect 4)
An image forming apparatus (U) according to a fourth aspect of the first invention is any one of the first to third aspects of the first invention.
The light-shielding layer formation control means (C4) for forming a latent image of the light-shielding layer forming image (1, 11) composed of a high density image by the latent image forming device (ROSy to ROSK);
It is provided with.
(Operation of the fourth aspect of the first invention)
In the image forming apparatus (U) according to the fourth aspect of the present invention, the light shielding layer formation control means (C4) is used for forming the light shielding layer composed of high density images by the latent image forming apparatuses (ROSi to ROSK). In order to form a latent image of the image (1, 11), the light shielding layer (1, 11, 21) can be formed without adding a new device to the conventional image forming apparatus (U).

(First embodiment 5)
An image forming apparatus (U) according to a fifth aspect of the first invention is any one of the first to third aspects of the first invention.
By the latent image forming devices (ROSy to ROSK), the image for forming the light shielding layer is lower as the density of the edge of the light shielding layer (21) is closer to the end along the rotation direction of the image carrier (Py to Pk). The light shielding layer formation control means (C4) for forming (1, 11),
It is provided with.
(Operation of the fifth aspect of the first invention)
In the image forming apparatus (U) according to the fifth aspect of the first invention, the light shielding layer formation control means (C4) rotates the image carrier (Py to Pk) by the latent image forming apparatuses (ROSi to ROSK). The light shielding layer forming image (1, 11) is formed such that the density of the end portion of the light shielding layer (21) decreases along the line. Therefore, it is possible to reliably shield light at a high density portion away from the end portion while suppressing the occurrence of the boundary line of the density difference in the printed image.

(First Embodiment 6)
An image forming apparatus (U) according to a sixth aspect of the first invention is the first invention,
The light-shielding layer (4) formed by spraying a liquid light-shielding material (3) in which toner is dispersed in a liquid as the light-shielding material (3) on the surface of the image carrier (Py to Pk);
It is provided with.
(Operation of the sixth aspect of the first invention)
In the image forming apparatus (U) according to the sixth aspect of the present invention, the light shielding layer (4) includes a liquid light shielding material (3) in which toner is dispersed in a liquid as the light shielding material (3). The surface of the image carrier (Py to Pk) can be protected from the external light by forming by spraying on the (Py to Pk) surface.

(First embodiment 7)
An image forming apparatus (U) according to a seventh aspect of the first invention is any one of the first invention and the first to sixth aspects of the first invention.
The cleaning device (CLy) having a cleaning member in contact with the image carrier (Py to Pk) and performing lubrication between the cleaning member and the image carrier (Py to Pk) by the collected light shielding material ~ CLk),
It is provided with.
(Operation of the first aspect 7)
In the image forming apparatus (U) according to the seventh aspect of the first invention, the cleaners (CLy to CLk) have a cleaning member that contacts the image carrier (Py to Pk), and the collected light shielding material Since lubrication between the cleaning member and the image carrier (Py to Pk) is performed, friction generated between the cleaning member and the surface of the image carrier (Py to Pk) is reduced, and the cleaning member and It can be prevented that the frictional force between the surfaces of the image holding bodies (Py to Pk) becomes excessive and the cleaning member is turned or chipped.

(Embodiment 8 of the first invention)
An image forming apparatus (U) according to a eighth aspect of the first invention is the image forming apparatus (U) according to any one of the first invention and the first to seventh aspects.
The light shielding layer (1, 4, 11, 21) having an area of 50% or more based on the total surface area of the image carrier (Py to Pk);
It is provided with.
(Operation of the eighth aspect of the first invention)
In the image forming apparatus (U) according to the eighth aspect of the present invention, the light shielding layer (1, 4, 11, 21) has an area of 50% or more with respect to the total surface area of the image carrier (Py to Pk). Can be protected.

(Second invention)
The image carrier (Py to Pk) of the second invention is externally provided by a light shielding layer (1, 4, 11, 21) made of a light shielding material that can be removed by a cleaner (CLy to CLk) that cleans the surface. The exposed exposed surface is covered.

(Operation of the second invention)
The image carrier (Py to Pk) of the second invention having the above-described configuration is a light shielding layer (1, 4, 11, 21) composed of a light shielding material that can be removed by a cleaner (CLy to CLk) that cleans the surface. ) Can protect the exposed surface exposed to the outside. Further, after removing the light shielding layer (1, 4, 11, 21) from the surface of the image carrier (Py to Pk) with a cleaner (CLy to CLk), the image carrier (Py to Pk) An image can be formed.

(Third invention)
The image carrier unit (Uy to Uk) of the third invention is
An image carrier (Py to Pk) in which an exposed surface exposed to the outside is covered with a light shielding layer (1, 4, 11, 21) made of a light shielding material;
A cleaner (CLy to CLk) for removing the light shielding layer (1, 4, 11, 21) on the surface of the image carrier (Py to Pk) and cleaning the image carrier (Py to Pk);
It is provided with.

(Operation of the third invention)
In the image carrier unit (Uy to Uk) of the third invention having the above-described configuration, the cleaners (CLy to CLk) are externally provided by the light shielding layers (1, 4, 11, 21) made of a light shielding material. The exposed exposed surface can be protected. After cleaning the image carrier (Py to Pk) by removing the light shielding layer (1, 4, 11, 21) from the surface of the image carrier (Py to Pk) with a cleaner (CLy to CLk) An image can be formed on the image carrier (Py to Pk).

The above-described present invention has the following effect (E01).
(E01) The surface of the photoreceptor can be protected from external light with a simple configuration.

Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention.
In FIG. 1, an image forming apparatus U includes a user interface UI as an example of an operation unit, an image input apparatus U1 as an example of an image information input apparatus, a paper feeding apparatus U2, an image forming apparatus main body U3, and a paper processing apparatus U4. Have.

The user interface UI has a copy start key, a copy number setting key, an input key such as a numeric keypad, and a display UI1.
The image input device U1 includes an automatic document feeder and an image scanner as an example of an image reading device. In FIG. 1, an image input apparatus U1 reads a document (not shown), converts it into image information, and inputs it to the image forming apparatus body U3.
The sheet feeding device U2 takes out the sheet feeding trays TR1 to TR4 as an example of a plurality of sheet feeding units, and the recording sheet S as an example of a medium accommodated in each of the sheet feeding trays TR1 to TR4, and the image forming apparatus body U3. A sheet feeding path SH1 and the like for conveying the sheet.

In FIG. 1, an image forming apparatus main body U3 includes an image recording unit that records an image on a recording sheet S conveyed from the sheet feeding device U2, a toner dispenser device U3a, a sheet conveyance path SH2, a sheet discharge path SH3, a sheet reversal. A path SH4, a paper circulation path SH6, and the like. The image recording unit will be described later.
The image forming apparatus main body U3 includes a control unit C, a laser drive circuit D as an example of a latent image writing device drive circuit controlled by the control unit C, and a power supply circuit E controlled by the control unit C. Etc. The laser drive circuit D whose operation is controlled by the control unit C is a laser corresponding to image information of Y (yellow), M (magenta), C (cyan), and K (black) input from the image input device U1. The drive signal is output to the latent image forming apparatuses ROSy, ROSm, ROSc, and ROSk of each color at a predetermined timing.
Below each of the latent image forming apparatuses ROSy, ROSm, ROSc, and ROSk of the respective colors, a drawing position where the drawing member U3b for the image forming unit is drawn to the front of the image forming apparatus main body U3 by a pair of left and right guide members R1 and R1. And a mounting position mounted in the image forming apparatus main body U3.

FIG. 2 is an explanatory view of a visible image forming apparatus having an image carrier unit and a developing device.
1 and 2, a black image carrier unit UK includes a photosensitive drum Pk as an example of an image carrier, a charger CCk, and a cleaner (cleaner) CLk as an example of an image carrier cleaner. Have. The other color (Y, M, C) image carrier units UY, UM, UC are also charged with photoreceptor drums Py, Pm, Pc, chargers CCy, CCm, CCc, cleaner CLy, as an example of a discharger. CLm, CLc. In Example 1, the K photosensitive drum Pk, which is frequently used and has a lot of surface wear, is configured to have a larger diameter than the photosensitive drums Py, Pm, and Pc of other colors, and is capable of high-speed rotation. Long life has been achieved.
The toner image forming members (UY + GY), (UM + GM), (UC + GC) are constituted by the developing units GY, GM, GC, GK having the image carrier units UY, UM, UC, UK and the developing roll R0 (see FIG. 2). , (UK + GK). The image forming unit drawing member U3b (see FIG. 1) is detachably mounted with the image carrier units UY, UM, UC, UK and developing units GY, GM, GC, GK.

  In FIG. 1, photosensitive drums Py, Pm, Pc, and Pk are uniformly charged by chargers CCy, CCm, CCc, and CCk, respectively, and then output from the latent image forming devices ROSy, ROSm, ROSc, and ROSk. An electrostatic latent image is formed on the surface of the laser beam Ly, Lm, Lc, Lk as an example of the latent image writing light. The electrostatic latent images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are Y (yellow), M (magenta), C (cyan), and K (black) colors by developing units GY, GM, GC, and GK. The toner image is developed.

The toner images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are transferred onto an intermediate transfer belt B as an example of an intermediate transfer member by primary transfer rolls T1y, T1m, T1c, and T1k as an example of a primary transfer unit. The images are sequentially superimposed and transferred, and a multicolor image, so-called color image, is formed on the intermediate transfer belt B. The color image formed on the intermediate transfer belt B is conveyed to the secondary transfer area (image recording position) Q4.
In the case of only black image data, only the K (black) photosensitive drum Pk and the developing device GK are used, and only a black toner image is formed.
After the primary transfer, residual toner on the surface of the photosensitive drums Py, Pm, Pc, and Pk is cleaned by the photosensitive drum cleaners CLy, CLm, CLc, and CLk.

Below the image forming unit drawing member U3b, there is a space between the drawing position where the intermediate transfer member drawing member U3c is drawn to the front of the image forming apparatus body U3 and the mounting position where the image forming apparatus body U3 is mounted. It is supported so that it can move. The intermediate transfer member pull-out member U3c allows the belt module BM as an example of an intermediate transfer device to come into contact with the lower surface of the photosensitive drums Py, Pm, Pc, and Pk and to move down from the lower surface. It is supported so that it can move up and down.
The belt module BM includes the intermediate transfer belt B, a belt support roll (Rd, Rt, Rw, Rf, T2a) as an example of an intermediate transfer member support member, and the primary transfer rolls T1y, T1m, T1c, T1k. And have. The belt support roll (Rd, Rt, Rw, Rf, T2a) includes a belt drive roll Rd as an example of an intermediate transfer member drive member, a tension roll Rt as an example of a tension applying member, and a walking roll as an example of a meandering prevention member. Rw, a plurality of idler rolls Rf as an example of a driven member, and a backup roll T2a as an example of a secondary transfer counter member. The intermediate transfer belt B is supported by the belt support rolls (Rd, Rt, Rw, Rf, T2a) so as to be rotatable in the arrow Ya direction.

A secondary transfer unit Ut is disposed below the backup roll T2a. A secondary transfer roll T2b as an example of a secondary transfer member of the secondary transfer unit Ut is disposed so as to be separated from and contactable with the backup roll T2a with the intermediate transfer belt B interposed therebetween. The secondary transfer roll T2b is A secondary transfer region Q4 is formed by the region in pressure contact with the intermediate transfer belt B. Further, a contact roll T2c as an example of a voltage application contact member is in contact with the backup roll T2a, and a secondary transfer device T2 is constituted by the rolls T2a to T2c.
A secondary transfer voltage having the same polarity as the charging polarity of the toner is applied to the contact roll T2c from the power supply circuit controlled by the control unit C at a predetermined timing.

A sheet conveyance path SH2 is disposed below the belt module BM. The recording sheet S fed from the sheet feeding path SH1 of the sheet feeding device U2 is conveyed to the sheet conveying path SH2, and a toner image is transferred to the secondary transfer region Q4 by a registration roll Rr as an example of a sheet feeding timing adjusting member. At the same time, it is conveyed to the secondary transfer region Q4 through the medium guide member SGr and the pre-transfer medium guide member SG2.
The medium guiding member SGr is fixed to the image forming apparatus main body U3 together with the registration roll Rr.
The toner image on the intermediate transfer belt B is transferred to the recording paper S by the secondary transfer device T2 when passing through the secondary transfer region Q4. In the case of a full-color image, the toner images primarily transferred onto the surface of the intermediate transfer belt B are secondarily transferred onto the recording paper S all at once.

The intermediate transfer belt B after the secondary transfer is cleaned, that is, cleaned by a belt cleaner CLB as an example of an intermediate transfer body cleaner. The secondary transfer roll T2b and the belt cleaner CLB are supported so as to be separated from and in contact with the intermediate transfer belt B.
A transfer device (T1 + B + T2 + CLB) for transferring the image on the surface of the photosensitive drums Py to Pk onto the recording paper S by the primary transfer rolls T1y, T1m, T1c, T1k, the intermediate transfer belt B, the secondary transfer device T2, the belt cleaner CLB, and the like. ) Is configured.

The recording sheet S on which the toner image is secondarily transferred is conveyed to the fixing device F through a post-transfer medium guide member SG2 and a sheet conveyance belt BH as an example of a medium medium member before fixing. The fixing device F has a heating roll Fh as an example of a heat fixing member and a pressure roll Fp as an example of a pressure fixing member, and is fixed by a region where the heating roll Fh and the pressure roll Fp are in pressure contact with each other. Region Q5 is formed.
The toner image on the recording paper S is heated and fixed by the fixing device F when passing through the fixing region Q5. A transport path switching member GT1 is provided on the downstream side of the fixing device F. The transport path switching member GT1 selectively selects the recording sheet S transported through the sheet transport path SH2 and heated and fixed in the fixing region Q5 to either the sheet discharge path SH3 or the sheet reversing path SH4 side of the sheet processing apparatus U4. Switch to. The sheet S conveyed to the sheet discharge path SH3 is conveyed to the sheet conveyance path SH5 of the sheet processing apparatus U4.

  A curl correction device U4a is disposed in the middle of the sheet conveyance path SH5, and a switching gate G4 as an example of a conveyance path switching member is disposed in the sheet conveyance path SH5. The switching gate G4 causes the first curl correction member h1 or the second curl correction member h2 to move the recording sheet S conveyed from the sheet conveyance path SH3 of the image forming apparatus main body U3 according to the direction of curving, so-called curl. Transport to either side of The recording paper S conveyed to the first curl correction member h1 or the second curl correction member h2 is curled when passing. The recording sheet S with the curl corrected is in a so-called face-up state in which the image fixing surface of the sheet faces upward from a discharge roll Rh as an example of a discharge member to a discharge tray TH1 as an example of a discharge unit of the paper processing device U4. It is discharged at.

The sheet S conveyed to the sheet reversing path SH4 side of the image forming apparatus main body U3 by the conveyance path switching member GT1 passes through the conveyance direction regulating member constituted by an elastic thin film member, so-called mylar gate GT2. Then, the sheet is conveyed to the sheet reversing path SH4 of the image forming apparatus main body U3.
A sheet circulation path SH6 and a sheet reversing path SH7 are connected to the downstream end of the sheet reversing path SH4 of the image forming apparatus body U3, and a mylar gate GT3 is also disposed at the connecting portion. The sheet conveyed through the switching gate GT1 to the sheet conveying path SH4 is conveyed to the sheet reversing path SH7 side of the sheet processing apparatus U4 through the mylar gate GT3. When performing duplex printing, the recording paper S that has been transported through the paper reversing path SH4 passes through the Mylar gate GT3 as it is, is transported to the paper reversing path SH7, and then transported in the opposite direction. When switched back, the transport direction is regulated by the mylar gate GT3, and the recording sheet S that has been switched back is transported to the paper circulation path SH6. The recording sheet S conveyed to the sheet circulation path SH6 is retransmitted to the transfer area Q4 through the sheet feeding path SH1.

On the other hand, when the recording paper S conveyed on the paper reversing path SH4 is switched back after the trailing edge of the recording paper S passes through the Mylar gate GT2 and before passing through the Mylar gate GT3, the Mylar gate GT2 causes the recording paper S The transport direction is regulated, and the recording paper S is transported to the paper transport path SH5 with the front and back sides reversed. The recording sheet S whose front and back sides are reversed is subjected to curl correction by the curl correction member U4a, and then the image fixing surface of the sheet S faces downward in the sheet discharge tray TH1 of the sheet processing apparatus U4, so-called face-down state. Can be discharged.
A sheet transport path SH is constituted by the elements indicated by the symbols SH1 to SH7. Further, the sheet conveying device SU is constituted by the elements indicated by the symbols SH, Ra, Rr, Rh, SGr, SG1, SG2, BH, GT1 to GT3.

(Description of control unit)
FIG. 3 is a block diagram of the control unit of the image forming apparatus according to the first exemplary embodiment of the present invention.
In FIG. 3, the controller C stores I / O (input / output interface) that performs input / output of signals to / from the outside and adjustment of input / output signal levels, programs and data for performing necessary processing, and the like. ROM (read-only memory), RAM (random access memory) for temporarily storing necessary data, CPU (central processing unit) that performs processing according to the program stored in the ROM, clock oscillator, etc. Various functions can be realized by executing a program stored in the ROM.

(Signal input element connected to the controller C)
The controller C receives an output signal from the next signal output element UI (user interface) or the like.
UI: User Interface The user interface UI includes a display unit UI1, a start key UI2, a photoconductor light shielding process start key UI3, and the like.

(Controlled element connected to controller C)
The controller C outputs a control signal for the next controlled element.
IPS: Image Processing System The image processing system IPS converts the read image signal input from the CCD into a digital image write signal and outputs it to the laser drive signal output circuit DL.
DL: Laser Drive Circuit The laser drive circuit DL outputs laser drive signals to ROSy to ROSK (latent image forming apparatus) in accordance with the input image writing signal. In response to the laser drive signal, laser beams Ly to Lk emitted from laser diodes (not shown) of ROSy to ROSK (latent image forming apparatuses) scan the surfaces of the photoreceptors Py to Pk, and the photosensitive An electrostatic latent image is formed on the surfaces of the bodies Py to Pk.

D1: Main motor drive circuit The main motor drive circuit D1 drives the main motor M1, thereby developing rollers R0, R0, R0, R0 of the developing unit G, photoconductors Py to Pk, chargers CCy to CCk, 1 The secondary transfer rolls T1y to T1k, the secondary transfer roll T2b, the heating roll Fh of the fixing device F, the intermediate transfer belt B, and the like are driven to rotate.

E: Power supply circuit The power supply circuit E includes development bias power supply circuits E1y to E1k and charging power supply circuits E2y to E2.
k, transfer power supply circuits E3y to E3k, E3t, and fixing power supply circuits E4y to E4k.
E1y to E1k: Power supply circuit for developing bias The power supply circuits for developing bias E1y to E1k apply a developing bias to the developing roll R0 of the developing devices GY to GK.
E2y to E2k: Charging power supply circuit The charging power supply circuit E2 applies a charging bias to the charging rolls CCy to CCk.
E3y to E3k, E3t: transfer power supply circuit The transfer power supply circuits E3y to E3k, E3t apply a transfer bias to the transfer rolls T1y to T1k and T2b.
E4y to E4k: Fixing power supply circuit The fixing power supply circuits E4y to E4k supply heating power to the heating roll Fh.

(Function of the controller C)
The controller C has a program (function realization means) that realizes a function of executing a process according to an output signal from each signal output element and outputting a control signal to each control element. Next, a program (function realization means) for realizing various functions of the controller C will be described.
C1: Main motor rotation control means The main motor rotation control means C1 controls the operation of the main motor drive circuit D1, and the photosensitive members Py to Pk, the developing devices GY to GK, the fixing device F, the intermediate transfer belt B, etc. Control the rotation.
C2: Power supply circuit control means The power supply circuit control means C2 includes the following means C2a to C2d, and controls the power supply circuit E to control the development bias, charging bias, transfer bias, and heater of the heating roll Fh. Control on-off etc.

C2a: Development Bias Control Unit The development bias control unit C2a controls the operation of the development bias power supply circuits E1y to E1k and applies a development bias to the development roll R0 of the development units GY to GK.
C2b: Charging Bias Control Unit The charging bias control unit C2b controls the charging bias applied to the chargers CCy to CCk by controlling the operation of the charging bias power supply circuits E2y to E2k.
C2c: Transfer Bias Control Unit The transfer bias control unit C2c controls the operation of the transfer power supply circuits E3y to E3k, E3t and applies a transfer bias to be applied to the primary transfer rolls T1y to T1k and the secondary transfer roll T2b. .
C2d: Fixing power supply control means The fixing power supply control means C2d controls the operations of the fixing power supply circuits E4y to E4k to control the heaters of the heating roll Fh on and off.

C3: Latent image forming means The latent image forming means C3 controls the outputs of the laser beams Ly to Lk irradiated from the latent image forming devices ROSy to ROSK to the photosensitive bodies Py to Pk via the laser driving circuit DL, and performs photosensitivity. A latent image is formed on the surfaces of the bodies Py to Pk.
C4: Photoconductor light shielding treatment control means (light shielding layer formation control means)
The photoconductor light shielding process control means C4 includes a start key input detection means C4a, a light shielding agent application control means C4b, a light shielding position movement control means C4c, and a photoconductor light shielding process rotation time storage means C4d. The main motor rotation control means C1, A control signal is input to the power supply circuit control means C2 and the latent image forming means C3 to control the light shielding process for applying a light shielding agent to the surfaces of the photoreceptors Py to Pk.
C4a: Start key input determination means (light shielding layer formation start determination means)
The start key input determining means C4a determines whether or not an input signal from the image carrier light shielding process start key UI3 of the user interface UI has been received.
C4b: Light-shielding agent application control means The light-shielding agent application control means C4b applies bias to the developing devices GY to GK, the chargers CCy to CCk, the primary transfer rolls T1y to T1k, and the secondary transfer roll T2b at the time of photoconductor light shielding processing. A control signal for controlling the on / off control of the laser beam and the output of the laser beams Ly to Lk of the latent image forming devices ROSy to ROSK is output to the power supply circuit control unit C2 and the latent image forming unit C3. A developer as a light shielding agent is applied to the surfaces of the photoreceptors Py to Pk. The light-shielding agent application control unit of Example 1 forms high-density images, so-called solid images, on the surfaces of the photoreceptors Py to Pk with the laser beams Ly to Lk.

C4c: Light-shielding position movement control means The light-shielding position movement control means C4c moves the surface of the photoconductors Py to Pk coated with a light-shielding agent to a position where it may be exposed to light and needs to be shielded. The rotational positions of the photoreceptors Py to Pk are controlled. The light shielding position movement control unit C4c according to the first exemplary embodiment outputs a control signal for rotating the photoconductors Py to Pk in the reverse direction during the light shielding process to the main motor rotation control unit C1, so that the photoconductors Py to Pk are output. Control the rotational position of the surface.
C4d: Rotation time storage means during photoconductor light shielding process Rotation time storage means C4d during photoconductor light shielding process includes forward rotation time storage means C4d1 and reverse rotation time storage means C4d2, and stores the light on the surfaces of the photoreceptors Py to Pk. The control times t1 and t2 for applying the light-shielding agent to the surface that may be exposed are stored.
C4d1: Forward rotation time storage means The forward rotation time storage means C4d1 stores the forward rotation time t1 during which the photoreceptors Py to Pk are forwardly rotated during the photosensitive member light shielding process. In the normal rotation time storage unit of Example 1, the positive rotation time t1 is set to a time during which a light-blocking solid image is formed in an area corresponding to 60% of the surface of the photoreceptors Py to Pk in the circumferential direction. .
C4d2: Reverse rotation time storage means The reverse rotation time storage means C4d2 stores a reverse rotation time t2 for rotating the photoconductors Py to Pk in reverse during the photoconductor light shielding process. In the reverse rotation time storage unit of the first embodiment, in the first rotation time, in the reverse rotation time t2, the application portion of the solid image for shading on the surface of the photoconductors Py to Pk may be irradiated with light from above. A time for reverse rotation is set in order to move from the cleaners CLy to CLk to the portion between the developing rolls R0 on the surface of a certain photoreceptor Py to Pk.

TM1: Forward rotation time measuring timer The forward rotation time measuring timer TM1 measures the forward rotation time t1 of the photoconductors Py to Pk stored in the forward rotation time storage means C4d1.
TM2: Reverse rotation time measuring timer The reverse rotation time measuring timer TM2 measures the reverse rotation time t2 of the photoconductors Py to Pk stored in the reverse rotation time storage means C4d2.

(Description of Flowchart of Photoreceptor Shading Process of Example 1)
FIG. 4 is a flowchart of the photoconductor light shielding process according to the first exemplary embodiment.
The processing of each ST (step) in the flowchart of FIG. 4 is performed according to a program stored in the ROM or hard disk of the controller C. This process is executed in a multitasking manner in parallel with other various processes of the image forming apparatus U.
The flowchart shown in FIG. 4 is started when the image forming apparatus U is turned on.

In ST1 of FIG. 4, it is determined whether or not the image carrier light shielding process start key UI6 is selected. If no (N), ST1 is repeatedly executed, and if yes (Y), the process proceeds to ST2.
In ST2, the following processes (1) to (5) are executed, and the process proceeds to ST3.
(1) The main motor M1 is driven to rotate the photoreceptors Py to Pk in the forward direction.
(2) The charging bias of the chargers CCy to CCk is applied to charge the surfaces of the photoreceptors Py to Pk.
(3) The developing biases of the developing units GY to GK are applied to develop toner on the surfaces of the photoreceptors Py to Pk. In Example 1, the primary transfer bias is applied to the primary transfer devices T1y to T1k so that the solid images developed on the surfaces of the photoreceptors Py to Pk are not transferred to the intermediate transfer belt B when the light shielding toner is applied. Is not applied. It is also possible to apply a bias having a polarity opposite to that at the time of image formation so that the solid image is not copied onto the intermediate transfer belt B.
(4) A solid latent image is written on the surface of the photoreceptors Py to Pk by ROSy to ROSk.
(5) The intermediate transfer belt B is rotated forward by the main motor M1.

In ST3, the normal rotation time t1 is set in the normal rotation time timer TM1.
In ST4, it is determined whether or not the normal rotation time timer TM1 has timed up. If no (N), ST4 is repeatedly executed, and if yes (Y), the process proceeds to ST5.
In ST5, the following processes (1) to (5) are executed to apply toner as a light shielding agent to the surfaces of the photoreceptors Py to Pk, and the process proceeds to ST6.
(1) The driving of the main motor M1 is stopped, and the photoconductors Py to Pk are turned off.
(2) The bias application of the chargers CCy to CCk is stopped, and charging of the surfaces of the photoreceptors Py to Pk is stopped.
(3) Bias application of the developing devices GY to GK is stopped.
(4) The writing of the latent image by ROSy to ROSk is stopped.
(5) The driving of the main motor M1 is stopped and the intermediate transfer belt B is stopped.

In ST6, the following processes (1) to (3) are executed, and the process proceeds to ST7.
(1) The main motor M1 is driven to rotate the photoreceptors Py to Pk in reverse.
(2) The main motor M1 is driven to rotate the intermediate transfer belt B in the reverse direction.
(3) The reverse rotation time t2 is set in the reverse rotation time counting timer TM2.
In ST6, the reverse rotation of the photoconductors Py to Pk is such that the surface of the photoconductors Py to Pk coated with toner, which is a light shielding agent, may be exposed to the light and needs to be shielded. Done to move. Therefore, no image is formed on the surfaces of the new photoreceptors Py to Pk, and ROSy to ROSk, chargers CCy to CCk, developing units GY to GK, and primary transfer units T1y to T1k are set off.

In ST7, it is determined whether or not the reverse rotation time counting timer TM2 has expired. If no (N), ST7 is repeatedly executed, and if yes (Y), the process proceeds to ST8.
In ST8, the following processes (1) to (2) are executed, and the process returns to ST1.
(1) The driving of the main motor M1 is stopped, and the photoreceptors Py to Pk are stopped.
(2) The driving of the main motor M1 is stopped and the intermediate transfer belt B is stopped.

(Operation of Example 1)
FIG. 5 is a diagram for explaining the operation of the first embodiment, and shows a state where the forward rotation is stopped after the application of the developer as the light shielding agent is completed during the light shielding process of the photosensitive member.
FIG. 6 is a diagram for explaining the operation of the first embodiment. In the photosensitive member light-shielding process, the image carrier rotates reversely and moves to a position where external light can be shielded by the developer applied on the surface of the image carrier. FIG.
In the image forming apparatus U according to the first embodiment having the above-described configuration, when the photoconductor light shielding process start key UI3 is input and the photoconductor light shielding process is started, the photoconductors Py to Pk are the same as those in normal image formation. Starts normal rotation in the direction of rotation. The photosensitive drums Py to Pk that have started to rotate forward are written with a latent image for shading solid images on the surfaces of the photosensitive drums Py to Pk by ROSy to ROSK, and are developed by the developing roll R0 of the developing units GY to GK. A solid image is developed.
When the forward rotation time t1 has elapsed (see ST4 in FIG. 4), as shown in FIG. 5, a light-blocking solid image 1 is formed on the surface of the photoreceptors Py to Pk in a region corresponding to 60% in the circumferential direction. Stop forward rotation.

  The photoconductors Py to Pk that have stopped normal rotation then start reverse rotation. When the reverse rotation t2 elapses (see ST7 in FIG. 4), as shown in FIG. 6, the solid image 1 is a region where external light from above may be irradiated on the surfaces of the photoconductors Py to Pk, that is, a cleaner. It moves to a position that covers the entire region between CLy to CLk and the chargers CCy to CCk and between the chargers CCy to CCk and the developing devices GY to GK, stops reverse rotation, and The body shading process is terminated.

As a result, when the upper part of the image forming apparatus is opened, the external light applied to the surfaces of the photoconductors Py to Pk from above is blocked by the solid image 1 of the developer applied to the surfaces of the photoconductors Py to Pk. can do. Therefore, the surfaces of the photoreceptors Py to Pk can be protected from external light from above. As a result, it is possible to suppress the light fatigue on the surfaces of the photoreceptors Py to Pk, and to suppress the occurrence of image omission and density difference in the printed image. The solid image 1 applied to the surfaces of the photoreceptors Py to Pk is collected by the cleaners CLy to CLk during an initialization operation (so-called initialization) performed at the start of the image forming operation.
Further, in the image forming apparatus U according to the first embodiment, the developer used at the time of normal printing is used as a light-shielding agent. Therefore, it is not necessary to add a new part or device to shield external light. Therefore, in Example 1 of the present invention, the surfaces of the photoreceptors Py to Pk can be protected from external light with a simple configuration.

(Example 2)
Next, the second embodiment of the present invention will be described. In the description of the second embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be given. Omitted.
The second embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.

FIG. 7 is an enlarged explanatory view of a main part of the image forming apparatus according to the second embodiment of the present invention.
In the second embodiment, a new image carrier unit U that is exchanged depending on the lifetime of the photoreceptors Py to Pk or the like.
In the new image carrier units UY to UK mounted on the image forming apparatus U instead of Y to UK, the light shielding agent is applied to the photoreceptors Py to Pk before being shipped from the factory. In FIG. 7, the airbrush 2 disposed opposite to the surface of the photoconductors Py to Pk of Example 2 sprays the light shielding agent 3 from the jet nozzle 2a onto the surface of the photoconductors Py to Pk. The light-shielding agent layer 4 is formed by rotating the photoreceptors Py to Pk in the forward direction while spraying the light-shielding agent 3 with the air brush 2. After the light-shielding agent layer 4 is formed, the airbrush 2 is stopped, and the photosensitive members Py to Pk are reversely rotated and moved to a predetermined position, so that the photosensitive members Py to Pk are shielded from light by the light-shielding agent layer 4. Can be moved to the photosensitive member protection position to be protected.
The light-shielding agent 3 of Example 2 is composed of a hydrofluoroether 7100 that is a fluorinated solvent as a solvent and a developer that dissolves in the hydrofluoroether 7100 that is a fluorinated solvent as the solvent. The hydrofluoroether 7100 and the developer are mixed in a weight ratio of 10: 1.

(Operation of Example 2)
Since the new image carrier units UY to UK shipped from the factory are protected by the light shielding agent 4 during storage or transportation in a warehouse or the like, light fatigue can be prevented. Further, when an operator such as a user or a service engineer replaces the image carrier units UY to UK, the photoconductors Py to Pk are protected by the light-shielding agent layer 4, so that even if exposed to light during work, the light is not affected. Fatigue can be reduced. The light-shielding agent layer 4 on the surface of the photoreceptors Py to Pk of the new image carrier units UY to UK mounted on the image forming apparatus U is subjected to an initialization operation that is performed before starting the first print job after the mounting. And removed by the cleaners CLy to CLk.

Example 3
Next, the third embodiment of the present invention will be described. In the description of the third embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be given. Omitted.
The third embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.

FIG. 8 is an overall explanatory view of an image forming apparatus according to Embodiment 3 of the present invention.
In FIG. 8, the image forming apparatus U includes an automatic document feeder U1 and an image forming apparatus body U2 that supports the automatic document feeder U1 and has a transparent document reading surface PG at the upper end.
The automatic document feeder U1 includes a document feeding unit TG1 that stores a plurality of documents Gi to be copied, and a document feeding unit TG1 that is fed from the document feeding unit TG1 and passes a document reading position on the document reading surface PG. And a document discharge portion TG2 from which the document Gi conveyed is discharged.
The image forming apparatus main body U2 includes an operation unit UI through which a user inputs an operation command signal for starting an image forming operation, an exposure optical system A, and the like.

Reflected light from a document conveyed on the document reading surface PG by the automatic document feeder U2 or a document manually placed on the document reading surface PG is passed through the exposure optical system A by the solid-state image sensor CCD. It is converted into electrical signals of R (red), G (green), and B (blue).
The image information conversion unit IPS temporarily converts the RGB electrical signals input from the solid-state imaging device CCD into K (black), Y (yellow), M (magenta), and C (cyan) image information. The image information is stored and output to the latent image forming apparatus drive circuit DL as image information for forming a latent image at a predetermined timing.
When the document image is a single color image, so-called monochrome, only K (black) image information is input to the latent image forming device drive circuit DL.
The latent image forming device drive circuit DL has drive circuits (not shown) for the respective colors Y, M, C, and K, and outputs a laser drive signal corresponding to input image information at a predetermined timing. The laser beam is output to a latent image writing laser diode (not shown) of each color of the forming apparatus ROS.

FIG. 9 is an enlarged explanatory view of a main part of the image forming apparatus according to the third embodiment.
The visible image forming devices Uy, Um, Uc, Uk arranged above the latent image forming device ROS are respectively Y (yellow), M (magenta), C (cyan), and K (black). An apparatus for forming a toner image.
Laser beams Ly, Lm, Lc, and Lk as examples of Y, M, C, and K latent image writing lights emitted from the respective laser diodes of the latent image forming device ROS are rotated image carriers PRy and PRm, respectively. , PRc, PRk.
The Y visible image forming device Uy includes a rotating image carrier PRy, a charger CRy, a developing device Gy, a transfer device T1y, and an image carrier cleaner CLy. In the third exemplary embodiment, the developing device Gy includes a developing unit that can be attached to and detached from the image forming apparatus U. The image carrier PRy, the charger CRy, and the image carrier cleaner CLy include the image forming apparatus U. In contrast, the image holding unit is detachable integrally. That is, the visible image forming apparatus Uy according to the third embodiment includes a developing unit, an image holding unit, a transfer device T1y, and the like.
The visible image forming apparatuses Um, Uc, Uk are all configured in the same manner as the Y visible image forming apparatus Uy.

8 and 9, the image carriers Py, Pm, Pc, and Pk are charged by their respective chargers Cy, Cm, Cc, and Ck, and then at image writing positions Q1y, Q1m, Q1c, and Q1k. An electrostatic latent image is formed on the surface of the laser beams Ly, Lm, Lc, and Lk. The electrostatic latent images on the surfaces of the image carriers Py, Pm, Pc, and Pk are developed in the developing regions Q2y, Q2m, Q2c, and Q2k, as developing roller as an example of the developer carrier of the developing devices Gy, Gm, Gc, and Gk. A toner image as an example of a visible image is developed with the developer held in GRy, GRm, GRc, GRk.
The developed toner image is conveyed to primary transfer regions Q3y, Q3m, Q3c, and Q3k that are in contact with an intermediate transfer belt B as an example of an intermediate transfer member. The primary transfer units T1y, T1m, T1c, and T1k disposed on the back side of the intermediate transfer belt B in the primary transfer regions Q3y, Q3m, Q3c, and Q3k are supplied with a predetermined value from a power supply circuit E controlled by the control unit C. At this timing, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied.
The toner images on the image carriers Py to Pk are primarily transferred to the intermediate transfer belt B by the primary transfer units T1y, T1m, T1c, and T1k. Residual toner on the surface of the image carrier Py, Pm, Pc, Pk after the primary transfer is cleaned by the image carrier cleaner CLy, CLm, CLc, CLk. The cleaned surfaces of the image carriers Py, Pm, Pc, and Pk are recharged by the chargers CRy, CRm, CRc, and CRk.

  Above the image carriers Py to Pk, a belt module BM as an example of an intermediate transfer device that can move up and down and can be pulled out forward is disposed. The belt module BM includes an intermediate transfer belt B as an example of an intermediate transfer member, a belt drive roll Rd as an example of an intermediate transfer member drive member, a tension roll Rt as an example of an intermediate transfer member stretching member, and a meander prevention Belt support roll as an example of an intermediate transfer member support member including a walking roll Rw as an example of a member, an idler roll (free roll) Rf as an example of a driven member, and a backup roll T2a as an example of a secondary transfer region facing member (Rd, Rt, Rw, Rf, T2a) and the primary transfer units T1y, T1m, T1c, T1k. The intermediate transfer belt B is rotatably supported by the belt support rolls (Rd, Rt, Rw, Rf, T2a).

A secondary transfer roll T2b as an example of a secondary transfer member is disposed facing the surface of the intermediate transfer belt B in contact with the backup roll T2a, and a secondary transfer device T2 is configured by the rolls T2a and T2b. ing. Further, a secondary transfer region Q4 is formed in a region where the secondary transfer device T2b and the intermediate transfer belt B face each other.
The single-color or multi-color toner images transferred in succession on the intermediate transfer belt B by the transfer devices T1y, T1m, T1c, and T1k in the primary transfer areas Q3y, Q3m, Q3c, and Q3k are transferred to the secondary transfer area Q4. To be transported.

  Below the latent image forming device ROS, a pair of left and right guide rails GR as an example of a guide member that supports paper feed trays TR1 to TR3 as an example of a paper feed container so as to be able to enter and exit in the front-rear direction (X-axis direction). , GR are provided in three stages. The recording sheets S as an example of media stored in the paper feed trays TR1 to TR3 are taken out by a pick-up roll Rp as an example of a medium take-out member, and are separated one by one by a separating roll Rs as an example of a medium spreading member. The The recording sheet is transported along a sheet transport path SH, which is an example of a medium transport path, by a plurality of transport rolls Ra, which is an example of a medium transport member, and is disposed upstream of the secondary transfer region Q4 in the sheet transport direction. In addition, the image is sent to a registration roll Rr as an example of a transfer region conveyance timing adjusting member. A sheet conveying device (SH + Ra + Rr) is configured by the sheet conveying path SH, the sheet conveying roll Ra, the registration roll Rr, and the like.

The registration roll Rr conveys the recording sheet S to the secondary transfer area Q4 in time with the toner image formed on the intermediate transfer belt B being conveyed to the secondary transfer area Q4. When the recording sheet S passes through the secondary transfer region Q4, the backup roll T2a is grounded, and the secondary transfer unit T2b is charged with toner from the power supply circuit E controlled by the control unit C at a predetermined timing. A secondary transfer voltage having a polarity opposite to that of the polarity is applied. At this time, the color toner image on the intermediate transfer belt B is transferred to the recording sheet S by the secondary transfer device T2.
The intermediate transfer belt B after the secondary transfer is cleaned by a belt cleaner CLb as an example of an intermediate transfer body cleaner.

The recording sheet S on which the toner image is secondarily transferred has a fixing region Q5 which is a pressure contact region of a heating roll Fh as an example of a heating fixing member of the fixing device F and a pressure roll Fp as an example of a pressing fixing member. And heated and fixed when passing through the fixing region. The heat-fixed recording sheet S is discharged from a discharge roller Rh as an example of a medium discharge member to a discharge tray TRh as an example of a medium discharge portion.
Note that a release agent for improving the releasability of the recording sheet S from the heating roll is applied to the surface of the heating roll Fh by a release agent application device Fa.

  Above the belt module BM, developer cartridges Ky, Km, Kc, which are examples of developer supply containers for storing Y (yellow), M (magenta), C (cyan), and K (black) developers. , Kk are arranged. The developer contained in each developer cartridge Ky, Km, Kc, Kk is supplied from the developer supply path (not shown) to each developer Gy according to consumption of the developer in the developers Gy, Gm, Gc, Gk. , Gm, Gc, Gk. In Example 3, the developer is composed of a two-component developer including a magnetic carrier and a toner provided with an external additive.

In FIG. 8, the image forming apparatus U has an upper frame UF and a lower frame LF, and the upper frame UF is above the latent image forming apparatus ROS and the latent image forming apparatus ROS. , Ie, image carriers Py, Pm, Pc, Pk, developing devices Gy, Gm, Gc, Gk, a belt module BM, and the like are supported.
The lower frame LF includes a guide rail GR that supports the paper feed trays TR1 to TR3 and the paper feed members that feed paper from the trays TR1 to TR3, that is, a pickup roll Rp, a separation roll Rs, A sheet conveying roll Ra and the like are supported.

(Description of Control Unit of Example 3)
FIG. 10 is a block diagram of the control unit of the image forming apparatus according to the third embodiment of the present invention, and corresponds to FIG. 3 according to the first embodiment.
(Function of the controller C)
In FIG. 10, in the controller C of the third embodiment, the reverse rotation storage means C4d2 and the reverse rotation time count timer TM2 of the first embodiment are omitted, and the forward rotation time storage means C4d1 and the forward rotation time count timer TM1 are omitted. Instead, it has a normal rotation time storage means C4d1 'and a normal rotation time timer TM1'.
C4d1 ′: Forward rotation time storage means The forward rotation time storage means C4d1 ′ stores the forward rotation time t1 ′ during which the photoreceptors Py to Pk are forwardly rotated during the photoconductor light shielding process. In the positive rotation time storage means C4d1 ′ of the third embodiment, during the positive rotation time t1 ′, the development of the surfaces of the photoreceptors Py to Pk is performed by the application portion of the light shielding solid image formed on the surfaces of the photoreceptors Py to Pk. The time for covering the area from the rolls GRy to GRk to the image carrier cleaner CLy to CLk is set.
TM1 ': Forward rotation time timer The forward rotation time timer TM1' measures the forward rotation times t1 'of the photosensitive members Py to Pk stored in the forward rotation time storage means C4d1'.

(Explanation of Flowchart of Photoreceptor Shading Process of Example 3)
FIG. 11 is a flowchart of the photoconductor light shielding process according to the third embodiment, and corresponds to FIG. 4 according to the first embodiment.
In the description of the third embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In the photoconductor light shielding process of Example 3, the following ST3 ′ and ST4 ′ are executed in place of ST3 and ST4 of Example 1, and ST6 to ST8 of Example 1 are omitted.

In ST3 ′, the normal rotation time t1 ′ is set in the normal rotation time timer TM1 ′.
In ST4 ', it is determined whether or not the normal rotation time timer TM1' has expired. If no (N), ST4 'is repeatedly executed, and if yes (Y), the process proceeds to ST5.

(Operation of Example 3)
FIG. 12 is a diagram for explaining the operation of the third embodiment, and shows a state in which the forward rotation is stopped after the application of the developer as the light shielding agent is completed at the time of the photosensitive member light shielding process.
In the image forming apparatus U according to the third embodiment having the above-described configuration, when the photoconductor light shielding process is started, the photoconductors Py to Pk start normal rotation, and the surfaces of the photoconductors Py to Pk are shielded from light. The solid image 11 is developed.
When the normal rotation time t1 'elapses (see ST4' in FIG. 11), the surface of the photoconductors Py to Pk is shielded from light in a region covering a portion from the developing rolls GRy to GRk to the image carrier cleaners CLy to CLk. A solid image 11 is formed, and the forward rotation is stopped.
Therefore, in the image forming apparatus U of the third embodiment, the solid image 11 applied to the surfaces of the photoconductors Py to Pk by development is the photoconductor Py from the image carrier cleaners CLy to CLk to the developing rolls GRy to GRk. The upper outer peripheral surface of ~ Pk is covered.

  As a result, when the upper portion of the image carrier unit U image forming apparatus is opened, the external light applied to the surfaces of the photoconductors Py to Pk from above is applied to the surface of the developer applied to the surfaces of the photoconductors Py to Pk. The solid image 11 can be shielded from light. Further, in the image forming apparatus U of the third embodiment, as in the first embodiment, since the developer used during normal printing is used as a light blocking agent, it is necessary to add new parts and devices to block outside light. No effect similar to that of the first embodiment is achieved.

Example 4
Next, the fourth embodiment of the present invention will be described. In the description of the fourth embodiment, the same reference numerals are given to the components corresponding to the components of the third embodiment, and the detailed description thereof will be given. Omitted.
The fourth embodiment is different from the third embodiment in the following points, but is configured in the same manner as the third embodiment in other points.

(Description of Control Unit of Example 4)
FIG. 13 is a block diagram of the control unit of the image forming apparatus according to the fourth embodiment of the present invention, and corresponds to FIG. 10 according to the third embodiment.
(Function of the controller C)
In FIG. 13, the controller C of the fourth embodiment has a light-shielding agent application control means C4b ′ instead of the light-shielding agent application control means C4b of the third embodiment.
C4b ′: Light-shielding agent application control means The light-shielding agent application control means C4b ′ according to the fourth embodiment outputs a control signal to the latent image forming means C3, so that the latent image forming devices ROSy to ROSk are transmitted via the laser drive circuit DL. To control the outputs of the laser beams Ly to Lk irradiated to the photosensitive members Py to Pk, and form latent images on the surfaces of the photosensitive members Py to Pk so that the image density becomes thinner toward the both ends of the toner image. Let

FIG. 14 is a detailed explanatory diagram showing fluctuations in output of laser beams Ly to Lk of ROSy to ROSk according to the fourth embodiment.
In FIG. 14, the light-shielding agent application control unit C4b ′ according to the fourth embodiment sets the irradiation outputs of the laser beams Ly to Lk to P0 which is the weakest value at the latent image writing start time t3 when ROSy to ROSk. Start writing of an electrostatic latent image on the surface of Pk.
From the latent image writing start time t3 to the writing start side density change end time t4 when the time for completing the writing of the light-shielding toner image for 1 cm in the circumferential direction on the surface of the positively rotating photoreceptors Py to Pk has elapsed. During this period, the outputs of the laser beams Ly to Lk gradually increase, and increase at a constant rate so that the outputs of the laser beams Ly to Lk become Pmax at the writing start side density change end time t4. To do.
The outputs of the laser beams Ly to Lk are held at Pmax until the write end side density change start time t5 after a lapse of a predetermined time from the write start side density change end time t4.

Between the writing end side density change start time t5 and the latent image writing end time t6 of the light-shielding toner image, the outputs of the laser beams Ly to Lk are gradually decreased to set the latent image writing end time t6. Then, the outputs of the laser beams Ly to Lk are controlled so as to be P0.
In FIG. 14, when the latent image writing end time t6 is reached, the control of the output values of the laser beams Ly to Lk of ROSy to ROSK ends.
When the latent image formed in this way is developed by a developing device, the density of the light-shielding toner image decreases as it approaches the edge in a region 1 cm in the circumferential direction from both ends of the light-shielding toner image. An image is formed.

(Description of Flowchart of Photoreceptor Shading Process of Example 4)
FIG. 15 is a flowchart of the photoconductor light shielding process according to the fourth embodiment, and corresponds to FIG. 11 according to the third embodiment.
In the description of the fourth embodiment, components corresponding to those of the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In the photoconductor light shielding process of Example 4, the following ST2 ′ and ST5 ′ are executed in place of ST2 and ST5 of Example 3.

In ST2 ′, the following processes (1) to (5) are executed, and the process proceeds to ST3 ′.
(1) The main motor M1 is driven to rotate the photoreceptors Py to Pk in the forward direction.
(2) The charging bias of the chargers CCy to CCk is applied to charge the surfaces of the photoreceptors Py to Pk.
(3) Write the light-shielding latent images on the surfaces of the photoreceptors Py to Pk by controlling the outputs of the laser beams Ly to Lk of ROSy to ROSk.
(4) A developing bias of the developing units GY to GK is applied to develop the latent images on the surfaces of the photoreceptors Py to Pk into toner images. In Example 4, the primary transfer bias is applied to the primary transfer devices T1y to T1k so that the toner images developed on the surfaces of the photoreceptors Py to Pk are not transferred to the intermediate transfer belt B when the light shielding toner is applied. Is not applied. In addition, it is possible to apply a bias having a polarity opposite to that at the time of image formation so that the toner image is not transferred onto the intermediate transfer belt B.
(5) The intermediate transfer belt B is rotated forward by the main motor M1.

In ST5 ′, the following processes (1) to (5) are executed to apply toner as a light shielding agent to the surfaces of the photoreceptors Py to Pk, and the process returns to ST1.
(1) The driving of the main motor M1 is stopped, and the photoconductors Py to Pk are turned off.
(2) The bias application of the chargers CCy to CCk is stopped, and charging of the surfaces of the photoreceptors Py to Pk is stopped.
(3) Stop writing of the latent image for shading by ROSy to ROSk.
(4) Bias application of the developing devices GY to GK is stopped.
(5) The driving of the main motor M1 is stopped and the intermediate transfer belt B is stopped.

(Operation of Example 4)
FIG. 16 is a diagram for explaining the operation of the fourth embodiment. FIG. 16A is a diagram illustrating a state in which the forward rotation is stopped after the application of the developer as the light shielding agent is completed in the photosensitive member light shielding process, and FIG. 16A is a cross-sectional view taken along line XVIB-XVIB in FIG. 16A, and FIG. 16C is a diagram corresponding to FIG. 16B in the third embodiment.
16A and 16B, in the image forming apparatus U according to the fourth embodiment having the above-described configuration, the latent image forming apparatus ROSy˜ is started when writing of the light-shielding toner image 21 formed on the surfaces of the photoreceptors Py˜Pk is started. The output intensity of the laser beams Ly to Lk of ROSK increases gradually from P0 to Pmax. Conversely, at the end of writing, the voltage gradually decreases from Pmax to P0 (see FIG. 14). Therefore, the density of the light-shielding toner image 21 is low at the boundary between the both end portions 21a and 21a of the light-shielding toner image 21 and the non-formation portion 22 of the toner image on the surface of the photoreceptors Py to Pk. . Therefore, on the surface of the photoreceptors Py to Pk after the formation of the light shielding toner image 21, the density difference between the light shielding toner image 21 and the toner image non-forming portion 22 on the surface of the photoreceptors Py to Pk is small. Adjacent to each other.

In FIG. 16C, the light shielding solid image 11 formed on the surface of the photoconductors Py to Pk of Example 3 is entirely composed of a high-density solid image. The density difference becomes large at the boundary with the toner image non-forming portion. If the density difference becomes large at the boundary portion, the density difference may appear in the printed image developed across the light-shielding toner image forming portion and the toner image non-forming portion during printing after the solid image 11 is removed. In particular, the boundary line of the density difference may be generated in a linear shape at the boundary portion.
However, in Example 4, the density difference in the boundary portion between the light-shielding toner image 21 and the toner image non-forming portion 22 on the surface of the photoconductors Py to Pk is small, and the density increases as the distance from the boundary increases. It is possible to reliably shield light at a high density portion while suppressing the occurrence of the boundary line of the density difference in the printed image.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H04) of the present invention are exemplified below.
(H01) The present invention is not limited to the color image forming apparatus U, and can also be applied to a monochrome image forming apparatus.
(H02) In Examples 1 to 4, a light shielding layer such as a solid image or a toner image for light shielding is formed in a region corresponding to 60% of the surface of the photoreceptors Py to Pk in the circumferential direction, and the surfaces of the photoreceptors Py to Pk However, the ratio of the region where the light shielding layer is formed is not limited to this, and the light shielding layer needs to protect the surfaces of the photoreceptors Py to Pk from the external light irradiated on the surfaces of the photoreceptors Py to Pk. An area having an arbitrary width can be covered with the light shielding layer. At this time, the cleaners CLy to CLk can be contacted / separated from the photoconductors Py to Pk, and the developer can be applied to the entire surface by separating them when applying the light shielding agent. .
(H03) In Example 2, the light-shielding agent 3 sprayed on the surfaces of the photoreceptors Py to Pk was a mixture of hydrofluoroether 7100 and developer, but is not limited to this, and hydrofluoroether 7100 Any liquid light-shielding agent that can be applied to the surface of the photoreceptor can be employed. In addition, since it can collect | recover with cleaner CLy-CLk, although it is desirable to use the developer as a dispersoid of a liquid light-shielding agent, materials other than a developer can also be used.
(H04) In Example 4, an image having a light-shielding toner image having a lighter density as it approaches the edge is formed in an area 1 cm in the circumferential direction from both ends of the light-shielding toner image. Without being limited thereto, the length of the region where the density of the both end portions of the light-shielding toner image changes can be set to an arbitrary length.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is an explanatory view of a visible image forming apparatus having an image carrier unit and a developing device. FIG. 3 is a block diagram of the control unit of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 4 is a flowchart of the photoconductor light shielding process according to the first exemplary embodiment. FIG. 5 is a diagram for explaining the operation of the first embodiment, and shows a state in which the forward rotation is stopped after the application of the developer as the light shielding agent is completed during the photosensitive member light shielding process. FIG. 6 is a diagram for explaining the operation of the first embodiment. When the photosensitive member is shielded, the image carrier rotates backward and moves to a position where external light can be shielded by the developer applied on the surface of the image carrier. FIG. FIG. 7 is an enlarged explanatory view of a main part of the image forming apparatus according to the second embodiment of the present invention. FIG. 8 is an overall explanatory view of an image forming apparatus according to Embodiment 3 of the present invention. FIG. 9 is an enlarged explanatory view of a main part of the image forming apparatus according to the third embodiment. FIG. 10 is a block diagram of the control unit of the image forming apparatus according to the third embodiment of the present invention, and corresponds to FIG. 3 according to the first embodiment. FIG. 11 is a flowchart of the photoconductor light shielding process according to the third embodiment, and corresponds to FIG. 4 according to the first embodiment. FIG. 12 is a diagram for explaining the operation of the third embodiment, and shows a state in which the forward rotation is stopped after the application of the developer as the light shielding agent is completed during the light shielding process of the photosensitive member. FIG. 13 is a block diagram of the control unit of the image forming apparatus according to the fourth embodiment of the present invention, and corresponds to FIG. 10 according to the third embodiment. FIG. 14 is a detailed explanatory diagram showing fluctuations in output of laser beams Ly to Lk of ROSy to ROSk according to the fourth embodiment. FIG. 15 is a flowchart of the photoconductor light shielding process according to the fourth embodiment, and corresponds to FIG. 11 according to the third embodiment. FIG. 16 is a diagram for explaining the operation of the fourth embodiment. FIG. 16A is a diagram illustrating a state in which the forward rotation is stopped after the application of the developer as the light shielding agent is completed in the photosensitive member light shielding process, and FIG. 16A is a cross-sectional view taken along line XVIB-XVIB in FIG. 16A, and FIG. 16C is a diagram corresponding to FIG. 16B in the third embodiment.

Explanation of symbols

1, 4, 11, 21, ... light shielding layer,
3 ... light shielding material,
C4: light shielding layer formation control means,
C4a: light-shielding layer formation start determining means,
CCy to CCk, CRy to CRk ... charger,
CLy ~ CLk ... cleaner,
GY-GK, Gy-Gk ... developer,
Py to Pk: Image carrier,
ROSy to ROSk ... latent image forming device,
T1y to T1k ... transfer device,
U: Image forming apparatus.

Claims (11)

An image carrier in which an exposed surface exposed to the outside is covered by a light shielding layer made of a light shielding material;
A cleaner for cleaning the image carrier by removing the light shielding layer on the surface of the image carrier;
A charger for charging the surface of the image carrier from which the light shielding layer has been removed;
A latent image forming apparatus that forms a latent image on the surface of the image carrier charged by the charger;
A developing unit for developing the latent image on the surface of the image carrier into a visible image;
A transfer device for transferring a visible image on the surface of the image carrier to a medium;
An image forming apparatus comprising: A light shielding layer formation start determining means for determining whether or not to start the formation of the light shielding layer;
The image carrier, the charger, the latent image forming device, and the developing device are controlled to charge the surface of the image carrier, and a light shielding layer is formed on the charged surface of the image carrier by the latent image forming device. Forming a latent image of the image, forming a light-shielding layer by visualizing the latent image with the developing unit, and exposing the surface of the image carrier exposed to the outside when the image forming apparatus is opened A light shielding layer formation control means for coating the light shielding layer with the light shielding layer,
The image forming apparatus according to claim 1, further comprising: The exposed surface set from the surface facing the developing unit to the surface facing the cleaning unit along the rotation direction of the image carrier, and set on the upper side of the image carrier in the direction of gravity The exposed surface;
The light shielding layer formation control means for rotating the image carrier in the same rotational direction as in the image forming operation to form the light shielding layer;
The image forming apparatus according to claim 2, further comprising: The exposed surface set from the surface facing the cleaner to the surface facing the developer along the rotation direction of the image carrier, and set on the upper side of the image carrier in the direction of gravity The exposed surface;
After the image carrier is rotated in the same rotational direction as in the image forming operation to form the light shielding layer, the image carrier is moved during the image forming operation until the light shielding layer moves to a position corresponding to the exposed surface. Is said light shielding layer formation control means for rotating in the reverse rotation direction;
The image forming apparatus according to claim 2, further comprising: The light-shielding layer formation control means for forming a latent image of the light-shielding layer forming image composed of a high-density image by the latent image forming device;
The image forming apparatus according to claim 2, further comprising: The light-shielding layer formation control means for forming the light-shielding layer-forming image lower by the latent image forming device as the density of the end of the light-shielding layer is closer to the end along the rotation direction of the image carrier;
The image forming apparatus according to claim 2, further comprising: The light-shielding layer formed by spraying a liquid light-shielding material in which toner is dispersed in a liquid as the light-shielding material on the surface of the image carrier,
The image forming apparatus according to claim 1, further comprising: The cleaner having a cleaning member in contact with the image carrier, wherein lubrication between the cleaning member and the image carrier is performed by the collected light shielding material;
The image forming apparatus according to claim 1, further comprising: The light-shielding layer having an area of 50% or more with respect to the total surface area of the image carrier;
The image forming apparatus according to claim 1, further comprising:   An image carrier in which an exposed surface exposed to the outside is covered with a light shielding layer made of a light shielding material that can be removed by a cleaner that cleans the surface. An image carrier in which an exposed surface exposed to the outside is covered by a light shielding layer made of a light shielding material;
A cleaner for removing the light shielding layer on the surface of the image carrier and cleaning the image carrier;
An image carrier unit comprising: