JP2016177271A - Image formation device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device that can more surely prevent a photosensitive layer of a photoreceptor drum from being locally peeled off in an area around an end part of a charge roller.SOLUTION: An image formation device comprises: a light source 20 that emits electricity-removed light L removing a charge left behind on a surface of a photoreceptor drum 5 after a toner image is transferred by the surface of the photoreceptor drum 5 being irradiated; an intermediate transfer belt 11 that causes the electricity-removed light L emitted from the light source 20 to be reflected in a direction of the photoreceptor drum 5; and a shield member 100 that reduces an amount of light of a reflection component with which the photoreceptor drum 5 is to be irradiated by being reflected by means of the intermediate transfer belt 11 of the electricity-removed light L emitted from the light source 20. The shield member 100 is provided so that, regarding a rotation axial direction R of the photoreceptor drum 5, an amount of reduction in amount of light of the reflection component is larger at either end part of a charge region to be charged by a charge roller 6 of the surface of the photoreceptor drum 5 inside of a part of either end part of the charge region of the surface of the photoreceptor drum 5.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), a facsimile machine, and the like, which form an image on a recording medium using, for example, an electrophotographic image forming system. The present invention also relates to a process cartridge incorporated in the image forming apparatus.

  In an electrophotographic image forming apparatus, from the viewpoint of ozone suppression, as a charging member for charging a photosensitive drum, a contact charging type charging roller for charging a conductive member by contacting the photosensitive drum is widely used. Yes. When the photosensitive drum is charged by the charging roller, discharge occurs from the charging roller to the photosensitive drum. The amount of discharge from the end of the charging roller in the rotation axis direction (hereinafter simply referred to as the end) to the photosensitive drum is the amount of discharge from the center in the same direction (hereinafter simply referred to as the center) to the photosensitive drum. Larger than This is because in the vicinity of the end portion of the charging roller, in addition to the discharge in the vicinity of the contact portion between the charging roller and the photosensitive drum, a discharge also occurs from the end surface of the charging roller.

  Here, the surface of the photosensitive drum is easily scraped as the discharge amount increases. For this reason, in the rotation axis direction R of the photosensitive drum, the surface is more easily scraped near the end than in the vicinity of the center of the charging roller. If the surface of the photosensitive drum is easily scraped near the end of the charging roller as described above, the film thickness of the photosensitive layer is locally scraped and the pressure resistance decreases. If charging is performed in a state where the photosensitive layer is locally scraped, a current concentrates on the locally scraped portion, and an area that cannot be charged is generated around the area, which may cause a leak image.

  On the other hand, there has been proposed a method for suppressing local abrasion on the surface of the photosensitive drum that occurs near the end of the charging roller. For example, Patent Document 1 describes a configuration in which, among the static elimination light irradiated from the pre-exposure device to the surface of the photosensitive drum, the static elimination light irradiated near both ends of the charging roller is shielded by a shielding member. As a result, the amount of static elimination light applied to the vicinity of both ends of the charging roller is reduced, and when the photosensitive drum is charged again, the potential difference between the both ends of the charging roller and the photosensitive drum in the vicinity thereof is reduced. Can be suppressed.

JP 2008-52207 A

  In recent years, downsizing of the apparatus has been promoted. In particular, in an image forming apparatus that forms a tandem type color image, the pitch between the photosensitive drums is extremely narrow. Along with this, depending on the arrangement relationship of members such as the charging roller, it may be difficult to directly irradiate the photosensitive drum with all of the static elimination light emitted from the pre-exposure device. For this reason, in addition to the static elimination light (direct component) that is directly irradiated onto the photosensitive drum, the static elimination light (reflective component) reflected by the reflecting member is irradiated so that sufficient static elimination is performed. is there.

  However, in the configuration of Patent Document 1, a shielding member is provided for the purpose of shielding only the direct component. For this reason, in the configuration in which the reflection component is irradiated during static elimination, the shielding member may not completely shield the reflection component. In this case, there is a possibility that the photosensitive layer is locally scraped and a leak image is generated without completely suppressing the discharge near the end of the charging roller during charging.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus that can more reliably prevent the photosensitive layer of the photosensitive drum from being locally scraped near the end of the charging roller.

  In order to achieve this object, an image forming apparatus according to the present invention is an image forming apparatus that forms an image by transferring a toner image carried by a rotatable image carrier onto a transfer medium. A charging member that charges the carrier, a light source that emits light that irradiates the surface of the image carrier after the transfer of the toner image, and discharges charges remaining on the surface of the image carrier; Reflecting means for reflecting the emitted light in the direction of the image carrier, and of the light emitted from the light source, the amount of the reflected component irradiated to the image carrier by being reflected by the reflecting means A light amount reducing member for reducing the light amount, and the light amount reducing member is located at both ends of a charging region charged by the charging member on the surface of the image carrier with respect to a rotation axis direction of the image carrier. Of the surface of the image carrier Serial than the inner portion than the two ends, and being provided so as to increase the amount of reduction in light amount of the reflected component.

  With the above configuration, the potential difference between both ends of the charging roller and both ends of the charging region during charging is reduced, and discharge can be more reliably suppressed. Therefore, it is possible to more reliably prevent the photosensitive layer from being locally scraped at both ends of the charging area of the photosensitive drum.

1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. It is a figure explaining the structure of the pre-exposure apparatus and shielding member which concern on 1st Embodiment of this invention. It is a section schematic diagram explaining the composition of the shielding member concerning a 1st embodiment of the present invention. 6 is a table showing the relationship between the surface potential immediately before charging and the amount of abrasion of the photosensitive layer after charging at both ends of the charging region of the photosensitive drum according to the present invention. It is a cross-sectional schematic diagram explaining the structure of the shielding member which concerns on the modification of this invention. 6 is a graph showing experimental results of the amount of abrasion of the photosensitive layer when the image forming apparatus according to the present invention performs intermittent printing.

(First embodiment)
<Image forming apparatus>
First, the overall configuration of the image forming apparatus A according to the present invention will be described with reference to the drawings together with the operation during image formation.

  The image forming apparatus A according to this embodiment is a full-color laser printer that employs a tandem method and an intermediate transfer method in which photosensitive drums are arranged in a line. As shown in FIG. 1, the image forming apparatus A includes an image forming unit that transfers a toner image to a sheet, a sheet feeding unit that supplies the sheet to the image forming unit, and a fixing unit that fixes the toner image on the sheet. I have.

  The image forming unit includes a process cartridge 4 that can be attached to and detached from the main body of the image forming apparatus A, an intermediate transfer unit 10, a pre-exposure device 2 (static elimination unit), and a laser scanner unit 9.

  In the process cartridge 4, process cartridges 4y, 4m, 4c, and 4k corresponding to each color of yellow, magenta, cyan, and black are arranged in a line. Each process cartridge 4 includes an organic photoconductive layer (photosensitive layer), and includes a photosensitive drum 5 (5y, 5m, 5c, 5k) as an image carrier that is rotatably provided. In addition, a charging roller 6 (6y, 6m, 6c, 6k) is provided as a charging member that is provided facing the photosensitive drum 5 and charges the photosensitive drum 5 in contact therewith. Further, the developing device 7 (7y, 7m, 7c, 7k), the cleaning blade 8 (8y, 8m, 8c, 8k), and the shielding member 100 (100y, 100m, 100c, 100k) are provided.

  The pre-exposure device 2 (2y, 2m, 2c, 2k) is substantially orthogonal to the rotation direction of the photosensitive drum 5 in order to remove residual charges on the surface of the photosensitive drum 5 in preparation for the next image formation after the transfer process. Irradiation light L is applied to the surface of the photosensitive drum 5 from the direction.

  The shielding member 100 (shielding means) is provided on the optical path of the neutralizing light L in order to regulate the irradiation area of the neutralizing light L irradiated by the pre-exposure device 2 and reduce the amount of the neutralizing light L. The shielding member 100 shields the charge removal light L applied to both ends of a charging area (hereinafter simply referred to as a charging area Y) charged by the charging roller 6 in the rotation axis direction R of the photosensitive drum 5. By providing the shielding member 100 in the process cartridge 4, the distance between the photosensitive drum 5 and the shielding member 100 is reduced, and the shielding accuracy is further improved.

  The intermediate transfer unit 10 also includes a primary transfer roller 17 (17y, 17m, 17c, 17k) as a transfer member, an intermediate transfer belt 11, a driving roller 12, and a tension roller 13 as intermediate transfer members. The intermediate transfer unit 10 includes a secondary transfer roller 14b (transfer member), a secondary transfer counter roller 14a, and a cleaning device 18.

  The intermediate transfer belt 11 is an endless cylindrical belt, is in contact with the photosensitive drum 5, and the driving roller 12 receives a rotational force from a driving source such as a motor (not shown) in the direction of the arrow X shown in FIG. Rotate. The intermediate transfer belt 11 is stretched by a driving roller 12, a tension roller 13, and a secondary transfer counter roller 14a.

  The primary transfer roller 17 is provided in parallel with the respective photosensitive drums 5 via the intermediate transfer belt 11, presses the intermediate transfer belt 11 toward the photosensitive drum 5, and the intermediate transfer belt 11 and the photosensitive drum 5. Primary transfer portion N1 is formed.

  During image formation, when a control unit (not shown) issues a print signal, the sheets stacked and stored in the sheet stacking unit 1 are sent out to the image forming unit by the feeding roller 3.

  On the other hand, the surface of the photosensitive drum 5 is charged by the charging roller 6. Then, the laser scanner unit 9 emits laser light from a light source (not shown) provided inside, and irradiates the photosensitive drum 5 with the laser light. Thereby, an electrostatic latent image is formed on the surface of the photosensitive drum 5. The electrostatic latent image is developed by the developing device 7 to form a toner image on the photosensitive drum 5. The toner image formed on the photosensitive drum 5 of each process cartridge 4 is applied with a transfer bias having a polarity opposite to that of the toner to the primary transfer roller 17, so that an intermediate transfer belt which is a transfer medium at the primary transfer portion N <b> 1. 11 is primarily transferred. Thereafter, the intermediate transfer belt 11 rotates in the direction of the arrow X shown in FIG. 1, and the primary transferred toner image moves downstream in the rotation direction by the rotation of the intermediate transfer belt 11. Thereafter, the toner image reaches the secondary transfer portion N2 formed by the secondary transfer counter roller 14a and the secondary transfer roller 14b, and a secondary transfer bias (transfer voltage) is applied to the secondary transfer roller 14b to cause the toner image. The image is transferred to the sheet.

  The sheet on which the toner image has been transferred is sent to a fixing device 15 where the toner image is fixed on the sheet by being heated and pressed, and then conveyed by a discharge roller 16 and discharged to a discharge portion.

  After the image formation (after the transfer of the toner image carried on the photoconductive drum 5), the pre-exposure device 2 irradiates the surface of the photoconductive drum 5 with the neutralizing light L, and the residual charge on the surface of the photoconductive drum 5 is neutralized. This prepares for the next image formation.

<Pre-exposure device and shielding member>
Next, the configuration of the pre-exposure apparatus 2 and the shielding member 100 of the present embodiment will be described in detail with reference to the drawings.

  As shown in FIG. 2, the pre-exposure apparatus 2 has a configuration in which light sources 20 are arranged on a substrate 19 at equal intervals. In this embodiment, a chip-type LED having a small driving voltage and easy to miniaturize is used as the light source 20. The interval between the light sources is 28.5 mm. However, the present invention is not limited to this, and the light source 20 may be a method using a light guide or a method using a halogen lamp.

  Further, the static elimination light L irradiated by the pre-exposure device 2 is irradiated by being diffused radially from the light source 20 according to the irradiation angle and the light intensity. Here, the light directly irradiated to the photosensitive drum 5 in the static elimination light L is used as a direct component, and the light irradiated to the photosensitive drum 5 after being reflected by the intermediate transfer belt 11 as the reflecting means is reflected. Ingredients.

  In this embodiment, the surface layer of the intermediate transfer belt 11 is a surface layer obtained by applying a coating liquid containing a radiation curable monomer or oligomer component and then irradiating and curing with an energy ray. . The light reflectance is about 80%.

  Next, the configuration of the shielding member 100 will be described. Since the shielding member 100 is a member that shields the static elimination light L emitted from the pre-exposure device 2, it is desirable that the shielding member 100 be a member that does not transmit light. However, as will be described later, it is not necessary to completely block the static elimination light L applied to both ends of the charging region Y, and any configuration that reduces the light amount to a predetermined level or less is acceptable. That is, the shielding member 100 is a light amount reducing member that reduces the amount of light emitted from the light source 20 to the photosensitive drum 5.

  In this embodiment, since the charging roller 6 that is charged in contact with the photosensitive drum 5 is used, both ends of the charging region Y referred to here are the charging roller 6 in the rotation axis direction R of the photosensitive drum 5. It means the both ends of the contact area. In the present embodiment, with respect to the rotation axis direction R, the width of the contact area of the photosensitive drum 5 with the charging roller 6 is 228 mm, and both ends of the charging area Y are 1.0 mm inside from both ends of the contact area. It is an area up to. However, the setting of both end portions is an example, and is set as appropriate according to the shaving of the photosensitive drum 5. In general, it is preferable to set both end portions of the charging region Y as regions at both end portions of the charging region Y within 0.5 mm to 3.0 mm from the both ends of the contact region.

  As for the position where the shielding member 100 is provided, first, in order to shield the direct component of the static elimination light L, each end of the charging region Y and the center of each light source 20 that irradiates the static elimination light L to each of the ends. The shielding member 100 is provided between them. As a result, at least the direct component of the static elimination light L can be shielded to reduce the amount of light. That is, it is provided only at a position where the irradiation light amount at the end of the charging area Y is reduced with respect to the rotation axis direction R of the photosensitive drum 5.

  Further, since the shielding member 100 shields the reflection component of the static elimination light L, it is closer to the intermediate transfer belt 11 side (reflection means side) than the tangent line V with the photosensitive drum 5 passing through the center of the light source 20 of the static elimination light L. Provide to protrude. Of course, the light source 20 here means the light source 20 of the static elimination light L irradiated to each end of the charging region Y. This is because the reflection component of the static elimination light L is on the intermediate transfer belt 11 side from the tangent line V to the photosensitive drum 5 passing through the center of the light source 20. Therefore, with such a configuration, at least a part of the reflection component can be shielded and the amount of light can be reduced.

  Depending on the pitch relationship between the light sources 20, there is a case where there is no end of the charging region Y on the tangent line V with the photosensitive drum 5 passing through the center of the light source 20. In this case, the shielding member 100 is provided so as to protrude toward the intermediate transfer belt 11 from the tangent plane including all the tangent lines V even when the tangent lines V with the photosensitive drum 5 passing through the center of the light source 20 do not completely intersect. . Thereby, the reflection component of the static elimination light L irradiated to the edge part of the charge area | region Y can be shielded. At this time, it can be said that the tangent line V includes the tangent plane.

  The above configuration will be described with further examples. As shown in FIG. 3, half of the direct component of the static elimination light L when the light emitted vertically from the light source 20 is direct light Ld and the light intensity of the direct light Ld of the reflection component is 100%. Intensity light is referred to as reflected light Lr. At this time, the shielding member 100 provided at the upper part of the frame is provided so as to protrude toward the intermediate transfer belt 11 from the tangent line V with the photosensitive drum 5 passing through the center of the light source 20.

  As a result, the shielding member 100 can shield both the direct light Ld, which is a direct component, and the reflected light Lr, which is a reflection component, of the static elimination light L. For this reason, the potential difference between both ends of the charging roller 6 and both ends of the charging region Y during charging is reduced, and discharge can be suppressed. Therefore, as compared with a configuration for the purpose of shielding only the direct component, it is possible to more reliably prevent the photosensitive layer from being locally scraped at both ends of the charging region Y and to prevent the occurrence of a leak image.

  In the present embodiment, a space is provided between the shielding member 100 and the intermediate transfer belt 11. However, the shield member 100 and the intermediate transfer belt 11 may be in contact with each other. Thereby, more reflection components can be shielded, and the light quantity of the static elimination light L can be further reduced.

  The shielding member 100 is more preferably a flexible member. Thereby, when the shielding member 100 is provided in contact with the intermediate transfer belt 11, it is possible to prevent the intermediate transfer belt 11 from being bent. At the same time, it is possible to prevent the shielding member 100 from being damaged by being pressed in the rotation direction of the intermediate transfer belt.

  In addition, the shielding member 100 does not necessarily need to have a configuration that completely blocks the static elimination light L applied to both ends of the charging region Y. That is, as described below, any configuration is possible as long as the potential difference between the charging roller 6 and both ends of the charging region Y is set to a predetermined value or less during charging.

  For example, FIG. 4 is a table showing the relationship between the surface potential immediately before charging (vertical axis) and the amount of abrasion of the photosensitive layer after charging (horizontal axis) at both ends of the charging region Y. In this embodiment, the surface potential of the photosensitive drum 5 immediately after charging is uniformly set to −600V. Further, regarding the amount of abrasion of the photosensitive layer, when the amount of abrasion of the photosensitive layer other than the both ends of the charged region Y is 100%, ○ is 100% or less, Δ is more than 100% and 110% or less, × The display means that the photosensitive layer at both ends of the charged region Y has been scraped more than 110%.

  As shown in the table of FIG. 4, the scraping amount at both ends of the charging area Y of the photosensitive drum 5 is larger than the area other than both ends when the surface potential at both ends of the charging area Y immediately before charging is −180V. The amount of abrasion of the photosensitive layer was 10% or more. On the other hand, when the surface potential at both ends of the charging region Y immediately before charging was −300 V, the amount of abrasion was the same as the amount of abrasion of the photosensitive layer in the region other than both ends. Therefore, it can be seen that if the surface potential at both ends of the charging region Y is set to −300 V immediately before charging, local abrasion of the photosensitive layer can be prevented.

  This means the following: That is, the surface potential of the photosensitive drum 5 immediately after charging is set to 100%, and the surface potential of the region where the electrostatic latent image is formed by laser irradiation by the laser scanner unit 9 after charging is set to 0%. At this time, the photosensitive member is locally localized by shielding the neutralizing light L so that the surface potential at both ends of the charging region Y immediately before charging (after irradiation with the neutralizing light L) is 50% or more by the shielding member 100. This means that it can be prevented from being scraped.

  Note that the shielding member 100 may be configured to partially shield the reflected light Lr of the static elimination light L that is applied to portions inside the charging region Y of the photosensitive drum 5 from both ends. In this case, the amount of decrease in the amount of the reflected light Lr irradiated to the photosensitive drum 5 by the shielding may be larger at both ends of the charging area Y than at the inner side of both ends of the charging area Y. . The same applies to the direct light Ld, and the shielding member 100 may be configured to partially shield the direct light Ld of the static elimination light L that is applied to the inner portions of both ends of the charging area Y of the photosensitive drum 5. Good. In this case, the amount of decrease in the amount of the direct light Ld irradiated to the photosensitive drum 5 due to the shielding may be larger at both ends of the charging area Y than at the inside of both ends of the charging area Y. .

<Modification>
Next, as a modification of the present embodiment, a configuration in which the shielding member 100 is bent on the intermediate transfer belt 11 side with respect to the tangent line V with the photosensitive drum 5 passing through the center of the light source 20 will be described.

  As shown in FIG. 5A, the shielding member 100 according to the modification is bent into an L shape or a T shape on the intermediate transfer belt 11 side from the tangent line V to the photosensitive drum 5 passing through the center of the light source 20. It is the structure to do. The direction of bending is bent in the same direction as the optical path direction of the charge removal light L from the light source 20 toward the end of the charging region Y.

  Here, the optical path direction of the static elimination light L from the light source 20 toward the end of the charging area Y indicates the optical path direction of the static elimination light L including both the reflection component and the direct component. The reflection component includes the optical path direction of the reflection component after being reflected by the intermediate transfer belt 11.

  That is, as shown in FIG. 5 (b), light directly irradiated from the light source 20 among the direct components of the static elimination light L is the direct light Ld, and the direct light Ld centered on the light source 20 has a radius. The semi-circle on the direct light Ld side is defined as a semi-circle C. At this time, the direction from the light source 20 toward the arc of the semicircle C, that is, the radial direction of the semicircle C (excluding the direction orthogonal to the direct light Ld) is the direction that can be the optical path direction of the static elimination light L. In particular, in the present embodiment, since the intermediate transfer belt 11 that forms the reflection component is on the upper side, the radial direction of the upper half with respect to the direct light Ld in the semicircle C is the optical path of the direct component or the reflection component before reflection. Indicates direction. Also, the radial direction of the lower half indicates the optical path direction of the direct component or the reflected component after reflection.

  With this configuration, when the shielding member 100 is in the optical path direction and bends toward the light source 20, the distance between the light source 20 and the shielding member 100 is reduced and the shielding efficiency of the reflection component is increased. Further, when the shielding member 100 is bent in the optical path direction and away from the light source 20, the distance between the charging region Y end and the shielding member 100 becomes short, and the shielding efficiency of the reflection component increases.

  Further, it is more preferable that the shielding member 100 bends in a direction parallel to the irradiation direction of the static elimination light L on the intermediate transfer belt 11 side with respect to the tangent line V with the photosensitive drum 5 passing through the center of the light source 20. This further increases the shielding efficiency. In addition, the irradiation direction here refers to the optical path direction of the direct light Ld irradiated perpendicularly from the light source 20 among the direct components of the static elimination light L.

  That is, as shown in FIG. 5A, the shape of the shielding member 100 is closer to the intermediate transfer belt 11 in the A1 direction orthogonal to the direct light Ld when viewed from the rotation axis direction R of the photosensitive drum 5. It is preferable that the shape be close to the light source 20 in the A2 direction parallel to the direct light Ld. This configuration increases the reflection component shielding efficiency.

  Alternatively, the shape of the shielding member 100 is such that the portion closer to the intermediate transfer belt 11 with respect to the A1 direction orthogonal to the direct light Ld when viewed from the rotation axis direction R of the photosensitive drum 5, with respect to the A2 direction parallel to the direct light Ld. A shape that is far from the light source 20 is preferable. This configuration increases the reflection component shielding efficiency.

<Experimental result>
Hereinafter, a result of a comparative experiment of the amount of abrasion of the photosensitive layer in the rotation axis direction R of the photosensitive drum 5 at the time of intermittent printing will be shown. In this experiment, a configuration in which the shielding member 100 is provided so as to protrude toward the intermediate transfer belt 11 from the tangent line V to the photosensitive drum 5 passing through the center of the light source 20 is referred to as an “embodiment”. In the configuration of the “embodiment”, a configuration in which the shielding member 100 is bent on the intermediate transfer belt 11 side with respect to the tangent line V is referred to as a “modified example”. A configuration in which the shielding member 100 is provided so as to shield only the direct component of the static elimination light L is referred to as a “comparative example”.

  As an experimental environment, the image forming apparatus was allowed to stand for 1 day at 15.0 ° C. and 10% Rh, and then the experiment was performed. In addition, the experiment contents are as follows: a horizontal line recording image with an image ratio of 2% is intermittently passed through every two sheets, and 1,000 sheets are printed, and after the initial surface film thickness and 1,000 sheets are printed. The amount of abrasion of the photosensitive layer was calculated from the difference from the surface film thickness.

  As a result, as shown in FIG. 6, in the configuration of “Comparative Example”, the photosensitive layer was greatly scraped at the end portion of the charging region Y, and local scraping of the photosensitive layer occurred in the rotation axis direction R of the photosensitive drum 5. This is because the shielding member 100 shields only the direct component of the static elimination light L, so that the reflection component is applied to the end of the charging region Y, and the discharge cannot be completely suppressed during charging.

  On the other hand, in the configuration of the “embodiment”, the amount of abrasion of the photosensitive layer is suppressed at the end portion of the charging region Y, and local abrasion of the photosensitive layer in the rotational axis direction R of the photosensitive drum 5 is eliminated. This is because the shielding member 100 shields not only the direct component but also the reflection component of the static elimination light L, so that the potential difference between the both ends of the charging roller 6 and the charging region Y end during charging is reduced, and the discharge is suppressed. It is.

  Further, in the configuration of the “variation example”, the amount of abrasion of the photosensitive layer is further suppressed at the end of the charging region Y. This is because the shielding member 100 shields not only the direct component of the static elimination light L but also the reflection component, and the shielding efficiency is high.

  From the above experimental results, it was confirmed that the photosensitive layer can be prevented from being locally scraped at the end of the charging region Y by the configuration of the present embodiment. Therefore, it has been confirmed that the configuration of the present embodiment can more reliably prevent the occurrence of a leak image.

  In the present embodiment, the pre-exposure device 2 is provided in the main body of the image forming apparatus A. However, the present invention is not limited to this, and the pre-exposure device 2 may be provided in the process cartridge 4. Since the position of the shielding member 100 is determined by the relative positional relationship with the position of the pre-exposure device 2, providing the both in the process cartridge 4 makes it easier to regulate the shielding area of the charge removal light L.

  In this embodiment, the intermediate transfer type image forming apparatus capable of forming a color image is exemplified. However, the present invention is not limited to this, and the present invention is also applicable to an image forming apparatus capable of forming a monochrome image. can do. In this case, a sheet or a transfer roller can be considered as the reflecting member that reflects the static elimination light L. In addition, it is good also as a structure which provides a reflecting member separately.

  Further, the image forming apparatus A may be a printer, a copier, a facsimile machine, or a multifunction machine that combines these functions. Further, the image forming apparatus may be an image forming apparatus that uses a recording agent carrier and sequentially superimposes and transfers toner images of respective colors on a recording material carried on the recording agent carrier.

DESCRIPTION OF SYMBOLS 1 ... Sheet stacking part 2 ... Pre-exposure device 3 ... Feed roller 4 ... Process cartridge 5 ... Photoconductor drum 6 ... Charge roller 7 ... Developing device 8 ... Cleaning blade 9 ... Laser scanner unit 10 ... Intermediate transfer unit 11 ... Intermediate transfer Belt 12 ... Driving roller 13 ... Tension roller 14a ... Secondary transfer counter roller 14b ... Secondary transfer roller 15 ... Fixing device 16 ... Discharge roller 17 ... Primary transfer roller 18 ... Cleaning device 19 ... Substrate 20 ... Light source 100 ... Shielding member A Image forming apparatus L Static elimination light Y Charging area V Tangent line with photosensitive drum passing through center of light source

Claims (16)

In an image forming apparatus for forming an image by transferring a toner image carried by a rotatable image carrier onto a transfer medium,
A charging member for charging the image carrier;
A light source that emits light that neutralizes charges remaining on the surface of the image carrier after transfer of the toner image by irradiating the surface of the image carrier;
Reflecting means for reflecting the light emitted from the light source in the direction of the image carrier;
Of the light emitted from the light source, a light amount reducing member that reduces the light amount of the reflection component irradiated to the image carrier by being reflected by the reflecting means;
With
The light quantity reducing member is such that the opposite ends of the charging area charged by the charging member on the surface of the image carrier are more in the direction of the rotation axis of the image carrier than the both ends of the surface of the image carrier. The image forming apparatus is provided so that the amount of decrease in the light amount of the reflection component is larger than the inner portion.   The light quantity reducing member is provided so as to protrude toward the reflecting means side from a tangent to the image carrier passing through the center of the light source among the light emitted from the light source. The image forming apparatus described in 1.   The image forming apparatus according to claim 1, wherein the light quantity reducing member is provided in contact with the reflecting unit.   The image forming apparatus according to claim 3, wherein the light amount reducing member is a flexible member.   5. The image forming apparatus according to claim 1, wherein the reflection unit is an intermediate transfer body on which a toner image is primarily transferred from the image carrier. 6.   The image forming apparatus according to claim 1, wherein the light amount reducing member is a member that does not transmit light emitted from the light source.   When viewed from the rotational axis direction of the image carrier, the light quantity reducing member is closer to the reflecting means in a direction closer to the reflecting means in a direction orthogonal to the direct light directly irradiated from the light source to the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus has a shape close to the light source in a parallel direction. Of the surface potential of the image carrier after charging, when the surface potential of the image carrier on which the electrostatic latent image is formed is 0%, and the surface potential of the other regions is 100%,
The light amount reducing member is configured to reduce the light emitted from the light source so that the surface potential at both ends of the charging region in the rotation axis direction of the image carrier is 50% or more after irradiation with the light emitted from the light source. The image forming apparatus according to claim 1, wherein the amount of light is reduced. The light amount reducing member reduces the light amount of the direct component directly irradiated to the image carrier among the light emitted from the light source,
The light quantity reducing member is configured to reduce the amount of light quantity of the direct component at both ends of the charging area charged by the charging member relative to the inner side of the both ends with respect to the rotation axis direction of the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided to be large. The rotatable image carrier is charged by the charging member, and a transfer voltage is applied to the transfer member to transfer the toner image formed on the image carrier to the transfer medium, and light is emitted from the light source to the surface of the image carrier. Is applied to the surface of the image carrier after the toner image is transferred, and the image forming apparatus includes a reflection unit that reflects the light emitted from the light source toward the image carrier. In the removable cartridge,
Of the light emitted from the light source, a light amount reducing member that reduces the light amount of the reflected component irradiated to the image carrier by being reflected by the reflecting means,
The light quantity reducing member is such that the opposite ends of the charging area charged by the charging member on the surface of the image carrier are more in the direction of the rotation axis of the image carrier than the both ends of the surface of the image carrier. Further, the cartridge is provided so as to increase the amount of decrease in the light amount of the reflection component as compared with the inner portion.   11. The light quantity reducing member is provided so as to protrude toward the reflecting means side from a tangent line with the image carrier passing through the center of the light source among the light emitted from the light source. Cartridge.   The cartridge according to claim 10 or 11, wherein the reflecting means is an intermediate transfer member on which a toner image is primarily transferred from the image carrier.   The cartridge according to any one of claims 10 to 12, wherein the light amount reducing member is a member that does not transmit light emitted from the light source.   When viewed from the rotational axis direction of the image carrier, the light quantity reducing member is closer to the reflecting means in a direction closer to the reflecting means in a direction orthogonal to the direct light directly irradiated from the light source to the image carrier. The cartridge according to any one of claims 10 to 13, wherein the cartridge is close to the light source in a parallel direction. Of the surface potential of the image carrier after charging, when the surface potential of the image carrier on which the electrostatic latent image is formed is 0%, and the surface potential of the other regions is 100%,
The light amount reducing member is configured to reduce the light emitted from the light source so that the surface potential at both ends of the charging region in the rotation axis direction of the image carrier is 50% or more after irradiation with the light emitted from the light source. The cartridge according to any one of claims 10 to 14, wherein the amount of light is reduced. The light amount reducing member reduces the light amount of the direct component directly irradiated to the image carrier among the light emitted from the light source,
The light quantity reducing member is configured to reduce the amount of light quantity of the direct component at both ends of the charging area charged by the charging member relative to the inner side of the both ends with respect to the rotation axis direction of the image carrier. The cartridge according to any one of claims 10 to 15, wherein the cartridge is provided to be large.