JP6285811B2 - Charger and image forming apparatus - Google Patents

Description

  The present invention relates to a charger and an image forming apparatus for charging a photoreceptor in an electrophotographic image forming process.

  In an electrophotographic image forming apparatus, an electrostatic latent image is formed on the surface of a photosensitive member by an exposure unit after the surface of the photosensitive member is charged by a charger, and toner is supplied by a developing unit to supply the electrostatic latent image. Is visualized as a toner image, and the toner image is directly or indirectly transferred from the surface of the photoreceptor to the paper. The toner remaining on the surface of the photoconductor after the transfer of the toner image causes image formation failure at the time of the next transfer, and is removed by, for example, a cleaning blade.

  The photosensitive member is less charged by the charger at both ends than at the center of the surface. For this reason, the toner supplied by the developing device may float inside the apparatus from both ends of the surface of the photoreceptor. When the floating toner adheres to the charger, it causes charging failure by the charger and may cause image formation failure.

  In order to prevent the floating toner from adhering to the charger, some cleaning blades are provided with a sealing material in contact with the surface of the photosensitive member at both ends (see, for example, Patent Document 1).

JP 2013-114244 A

  However, since the sealing material comes into contact with the surface of the photoconductor, air that flows inward from both ends of the housing is blocked and the surface of the photoconductor may be damaged. If the air flowing from both ends of the housing to the inside is blocked, the flow of the surrounding air changes, and the floating toner adheres to an unexpected part of the charger, causing image formation failure. Sometimes. In addition, the damaged surface of the photoconductor causes image formation failure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a charger and an image forming apparatus that can prevent floating toner from adhering without damaging the surface of a photoreceptor and without changing the flow of ambient air.

  The charger of the present invention includes a sealing material for preventing toner from entering the inside of the housing, and is used in an electrophotographic image forming apparatus. The longitudinal direction of the housing coincides with the axial direction of the photoreceptor. In addition, the open surface of the housing is disposed opposite to the surface of the photoconductor to charge the surface of the photoconductor. The sealing material is provided across the entire area of both ends on the open surface side of the casing in the longitudinal direction with a gap between the photoconductor and the casing.

  During the image forming process, the surface of the photoconductor is charged by a charger. Since both ends of the surface of the photoreceptor are less charged than the central portion, when toner is supplied from the developing device, the toner may float from both ends. Since the sealing material is provided at both ends of the open surface of the housing, the floating toner can be prevented from entering from the open surface side of the housing. In addition, the sealing material forms a predetermined gap between both ends of the open surface side of the housing and the surface of the photoconductor, so that the airflow to the housing is prevented without damaging the surface of the photoconductor. Do not block.

  The charger is provided with a sealing material for preventing toner from entering the inside of the housing, is used in an electrophotographic image forming apparatus, and the longitudinal direction of the housing is aligned with the axial direction of the photosensitive member, and The open surface of the housing is disposed opposite to the surface of the photoconductor to charge the surface of the photoconductor. The sealing material is located between the photosensitive member and the casing in a region on the upstream side in the moving direction of the surface of the photosensitive member arranged opposite to the casing, out of the entire area of both ends on the open surface side of the casing in the longitudinal direction. Are provided with a gap formed therebetween. The sealing material has an L-shape that bends the downstream side in the moving direction outward of both ends of the casing.

  The toner floats from the upstream side to the downstream side in the moving direction of the surface of the photoconductor disposed opposite to the housing by the wind accompanying the rotation of the photoconductor. Since the floating toner accumulates in a portion where the floating toner is bent outward at both ends of the casing, the floating toner can be prevented from entering from the open surface side of the casing. Further, since the sealing material forms a predetermined gap between both end portions on the open surface side of the housing and the surface of the photoconductor, the surface of the photoconductor is not damaged. Further, the seal material does not form a predetermined gap and is not provided in the downstream region in the moving direction of both end portions on the open surface side of the housing, so that the air flow to the housing is not further blocked. .

  The predetermined gap is preferably a gap that does not allow the sealing material to contact the surface of the photoreceptor. Since the charger has a small predetermined gap, it is possible to prevent the toner from entering through the predetermined gap.

  Moreover, it is preferable that the both ends of the transversal direction of a housing | casing have thickness rather than a center part as for a sealing material. In the case, both end portions in the short direction of the case are separated from the surface of the photoconductor than the center portion. However, since this sealing material can make the gap with the surface of the photoreceptor small, it is possible to further prevent the toner from entering.

  Further, it is preferable that the upstream side in the moving direction of the sealing material is thicker than the downstream side. The casing is further away from the surface of the photoconductor on the upstream side in the moving direction than on the downstream side. However, since this sealing material can make the gap with the surface of the photoreceptor small, it is possible to further prevent the toner from entering.

  In the configuration including the grid electrode provided on the entire open surface of the housing, it is preferable that the sealing material has a predetermined gap between the photoconductor and the grid electrode.

  Since the charger is provided with a sealing material so that a predetermined gap is formed between the grid electrode and the photosensitive member, the surface of the photosensitive member is not damaged by the sealing material, and air flow to the housing is prevented. The toner can be prevented from adhering to the grid electrode without being changed. For this reason, the charging failure of the charger can be prevented.

  The image forming apparatus of the present invention includes a photoreceptor, the above-described charger, and a transfer device. A toner image is formed on the surface of the photoreceptor. The charger charges the surface of the photoreceptor before a toner image is formed on the surface of the photoreceptor. The transfer device transfers the toner image directly or indirectly from the surface of the photoreceptor to the paper. Since the image forming apparatus can prevent charging failure of the charger, a good image can be formed.

  According to the present invention, it is possible to prevent floating toner from adhering to the charger without damaging the surface of the photosensitive member and without changing the air flow to the charger.

It is the schematic diagram which looked at the circumference of the charger concerning a 1st embodiment of this invention from the front. It is the schematic diagram which looked at the circumference of the charger from the upper surface. It is the schematic diagram which looked at the periphery of the charger which concerns on 2nd Embodiment from the upper surface. (A) is an example of the sealing material of the charger according to the third embodiment, and (B) is another example of the sealing material. (A) is an example of the sealing material of the charger according to the fourth embodiment, and (B) is another example of the sealing material.

  An image forming apparatus including a charger according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the image forming apparatus 100 includes, for example, a photosensitive drum 11, a charger 12, a developing device 13, and a cleaning blade 14, and uses image data input from an external device (not shown). An image forming process is performed on the paper by an electrophotographic method.

  Around the photosensitive drum 11, a charger 12 that charges the surface of the photosensitive drum 11 by corona discharge, a developing device 13 that visualizes an electrostatic latent image formed on the surface of the photosensitive drum 11 into a toner image, and A cleaning blade 14 for cleaning the surface of the photosensitive drum 11 is disposed.

  The photosensitive drum 11 is arranged with its axial direction aligned with the direction from the front side to the back side of the apparatus main body (not shown). The apparatus main body is provided with a fan (not shown) for taking in air outside the apparatus on the front side, and an exhaust port (not shown) for discharging the air inside the apparatus on the back side. Since air flows from the front side to the back side inside the apparatus main body, ozone generated by corona discharge of the charger 12 is discharged to the outside from the back side of the apparatus main body.

  The charger 12 aligns the longitudinal direction of the casing 121 with the axial direction of the photosensitive drum 11 and arranges the open surface 122 of the casing 121 to face the surface of the photosensitive drum 11. A discharge electrode 124 is stretched along the longitudinal direction of the casing 121 at the center of the casing 121. The discharge electrode 124 is a corona wire or a sawtooth electrode, and performs a corona discharge from the tip when a voltage is applied. The discharge area of the discharge electrode 124 coincides with the area including the image forming area (area where the toner image is formed) on the surface of the photosensitive drum 11 in the axial direction of the photosensitive drum 11.

  A mesh-like grid electrode 123 is disposed on the open surface 122 of the housing 121. The grid electrode 123 is provided with an opening along a central portion facing the discharge electrode 124. This opening allows the inside of the housing 121 to communicate with the space on the photosensitive drum 11 side.

  A cleaning blade 14 is disposed in the vicinity of the upstream side of the charger 12 in the moving direction of the surface of the photosensitive drum 11. The cleaning blade 14 removes the toner from the surface of the photosensitive drum 11 by bringing the tip portion 141 into contact with the surface of the photosensitive drum 11 in an obliquely upward direction of the charger 12.

  Further, the tip 141 of the cleaning blade 14 contacts the surface of the photosensitive drum 11 in a wider area than the image forming area on the surface of the photosensitive drum 11.

  A developing unit 13 is disposed in the vicinity of the downstream side of the charger 12 in the moving direction of the surface of the photosensitive drum 11. The developing unit 13 includes a storage unit 131 that stores toner, and supplies the toner to the electrostatic latent image formed on the surface of the photosensitive drum 11 to visualize the toner image.

  As shown in FIG. 2, seal materials 15 are provided at both ends of the cleaning blade 14 in the axial direction of the photosensitive drum 11. Each sealing material 15 is disposed outside the image forming area on the surface of the photosensitive drum 11 in the axial direction of the photosensitive drum 11 and so that the end of the cleaning blade 14 is positioned between both ends. Is done. Each sealing material 15 is disposed with a predetermined gap between the end of the cleaning blade 14 and the surface of the photosensitive drum 11. By being arranged in this way, the sealing material 15 prevents the toner leaking from both ends of the cleaning blade 14 during cleaning from floating inside the apparatus.

  Further, the charger 12 is provided with the sealing material 20 in each of the entire areas of both ends of the grid electrode 123 in the longitudinal direction of the casing 121. Each sealing material 20 is a PET material, and is provided outside the image forming area on the surface of the photosensitive drum 11 and inside the end of the cleaning blade 14 in the axial direction of the photosensitive drum 11. As shown in FIG. 1, the sealing material 20 is provided with a predetermined gap between the grid electrode 123 and the photosensitive drum 11. The predetermined gap is a gap that does not contact the surface of the photosensitive drum 11 with the sealing material 20. The sealing material 20 may be a moquette material instead of a PET material. By using the PET material, the manufacturing cost of the sealing material 20 can be reduced as compared with the case of using the moquette material.

  As described above, the sealing material 20 prevents the toner floating from both ends of the surface of the photosensitive drum 11 from entering the inside of the housing 121 and prevents the toner from adhering to the grid electrode 123. Further, the sealing material 15 prevents the toner leaking from both ends of the cleaning blade 14 from floating, but may leak slightly. The sealing material 20 also prevents the leaked toner from entering the housing 121 and adheres to the grid electrode 123.

  Further, since the sealing material 20 forms a predetermined gap between the grid electrode 123 and the photosensitive drum 11, the surface of the photosensitive drum 11 is not damaged and the air flow to the housing 121 is not blocked. . For this reason, the charger 12 can prevent image formation failure due to the surface of the photosensitive drum 11 being damaged and toner adhesion to an unexpected location due to a change in the air flow to the housing 121. As a result, the image forming apparatus 100 can prevent poor charging of the photosensitive drum 11 by the charger 12 and can perform good image formation.

  Further, since the sealing material 15 is provided outside the image forming area of the photosensitive drum 11, even if it contacts the surface of the photosensitive drum 11, the image forming area of the photosensitive drum 11 is hardly damaged and image formation is performed. Does not cause defects.

  An image forming apparatus including a charger according to a second embodiment of the present invention will be described with reference to FIG. The charger 12 includes a sealing material 21 having a different shape instead of the sealing material 20 according to the first embodiment. Only the differences will be described below.

  As shown in FIG. 3, the charger 12 has an upstream side in the moving direction of the surface of the photosensitive drum 11 disposed opposite to the casing 121 in the entire area of both ends of the grid electrode 123 in the longitudinal direction of the casing 121. The sealing material 21 is provided in this area. Each sealing material 21 has an L shape that bends the downstream side in the moving direction to the outside of the housing 121. Further, each sealing material 21 is a PET material or a moquette material, and in the axial direction of the photosensitive drum 11, outside the image forming area on the surface of the photosensitive drum 11 and in the longitudinal direction of the casing 121. It is provided inside the end portion. Further, the sealing material 21 is provided with a predetermined gap between the grid electrode 123 and the photosensitive drum 11. The predetermined gap is a gap that does not contact the surface of the photosensitive drum 11 with the sealing material 21.

  Note that the L-shape of the sealing material 21 that bends outside the housing 121 includes a shape that curves outside the housing 121.

  As described above, the sealing material 21 prevents the toner floating from both ends of the surface of the photosensitive drum 11 from being accumulated outside the housing 121, thereby preventing the toner from entering the housing 121. It is prevented from adhering to 123.

  In addition to forming a predetermined gap, the sealing material 21 is not provided in a region on the downstream side in the moving direction out of the entire area of both ends of the grid electrode 123 in the longitudinal direction of the casing 121. The air flow to 121 is not further blocked.

  An image forming apparatus including a charger according to a third embodiment of the present invention will be described with reference to FIG. The charger 12 includes a sealing material 22 having a different shape instead of the sealing material 20 according to the first embodiment. Only the differences will be described below.

  As shown in FIG. 4A, the seal material 22 has a surface on the side facing the surface of the photoconductive drum 11 along the surface of the photoconductive drum 11 with respect to the short direction of the housing 121 as a reference. It has an arc shape that protrudes downward. As shown in FIG. 4B, the seal material 22 has a surface on the side facing the surface of the photosensitive drum 11 from the center toward both ends with respect to the short direction of the casing 121. A shape protruding stepwise toward the photosensitive drum 11 may be exhibited.

  As a result, the sealing material 22 has both ends in the short side direction of the casing 121 thicker than the central portion, so that the gap with the surface of the photosensitive drum 11 can be made small, and the interior of the casing 121 can be reduced. Intrusion of toner into the toner can be further prevented.

  An image forming apparatus including a charger according to a fourth embodiment of the present invention will be described with reference to FIG. The charger 12 includes a sealing material 23 having a different shape instead of the sealing material 21 according to the second embodiment. Only the differences will be described below.

  As shown in FIG. 5A and FIG. 5B, the sealing material 23 has a moving direction of the surface of the photoconductor drum 11 disposed facing the housing 121 with respect to the short direction of the housing 121 as a reference. Since the upstream side is thicker than the downstream side, the same effect as the sealing material 22 can be obtained.

  In the above-described embodiment, the charger including the grid electrode 123 is described as an example. However, the present invention can also be applied to a charger that does not include the grid electrode 123.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 11 ... Photosensitive drum 12 ... Charger 20-23 ... Sealing material 121 ... Case 122 ... Open surface

Claims (6)

Used in an electrophotographic image forming apparatus, the longitudinal direction of the housing is made to coincide with the axial direction of the photoconductor, and the open surface of the housing is arranged to face the surface of the photoconductor, and the surface of the photoconductor A charger for charging
Wherein a housing seal member for preventing the toner from entering the interior of, said longitudinal said in the direction of the housing opening side of the both end portions, forming a gap between the photosensitive member and said casing Provided with a sealing material ,
The sealing material is a charger in which both end portions in the short direction of the casing are thicker than the center portion . Used in an electrophotographic image forming apparatus, the longitudinal direction of the housing is made to coincide with the axial direction of the photoconductor, and the open surface of the housing is arranged to face the surface of the photoconductor, and the surface of the photoconductor A charger for charging
A sealing material for preventing toner from entering the inside of the casing, and the surface of the photoconductor disposed opposite to the casing among both end portions on the open surface side of the casing in the longitudinal direction. In a region upstream of the moving direction, a sealing material provided with a gap formed between the photoconductor and the housing,
The said sealing material is a charger which exhibits the L shape which bends the downstream of the said moving direction to the outward of the both ends of the said housing | casing. Used in an electrophotographic image forming apparatus, the longitudinal direction of the housing is made to coincide with the axial direction of the photoconductor, and the open surface of the housing is arranged to face the surface of the photoconductor, and the surface of the photoconductor A charger for charging
A sealing material for preventing toner from entering the inside of the casing, and the surface of the photoconductor disposed opposite to the casing among both end portions on the open surface side of the casing in the longitudinal direction. In a region upstream of the moving direction, a sealing material provided with a gap formed between the photoconductor and the housing,
The sealing material is a charger in which the upstream side in the moving direction is thicker than the downstream side . The charger according to any one of claims 1 to 3, wherein the predetermined gap is a gap that does not contact the surface of the photoconductor . Further comprising a grid electrode provided on the entire open surface of the housing,
The charger according to any one of claims 1 to 4, wherein the sealing material is provided with the predetermined gap formed between the photoconductor and the grid electrode . A photoreceptor on which a toner image is formed;
The charger according to any one of claims 1 to 5, wherein the charger charges the surface of the photoreceptor before the toner image is formed on the surface of the photoreceptor.
An image forming apparatus comprising: a transfer unit that transfers a toner image directly or indirectly from the surface of the photosensitive member to a sheet .

Images