JP2020201319A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that has a light source for static elimination arranged to reduce the distance from the light source for static elimination to a light guide member.SOLUTION: An image forming apparatus 1 comprises a housing 2. The image forming apparatus 1 includes a process cartridge 50 that has a photoconductor drum 51 and a light guide member 56 guiding light for static elimination to the surface of the photoconductor drum 51 and is removably attached to the housing 2. The image forming apparatus 1 includes a belt unit 30 that has a belt opposite to the photoconductor drum 51 and a light source for static elimination 35 emitting light for eliminating static electricity on the photoconductor drum 51 toward the light guide member 56 and is removably attached to the housing 2.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus.

Conventionally, an electrophotographic image forming apparatus has been known as an image forming apparatus such as a printer. The electrophotographic image forming apparatus is provided with a static elimination light source for removing the charge of residual toner on the photosensitive drum and a light guide member for guiding the light of the static elimination light source to the surface of the photosensitive drum. Various arrangements have been proposed for the static elimination light source and the light guide member.

For example, Patent Document 1 discloses an image forming apparatus in which a light source for static elimination is provided in a main body of the apparatus and a light guide member is provided in an intermediate transfer belt unit. Further, Patent Document 2 discloses an image forming apparatus in which a light source for static elimination is provided in a main body of the apparatus and a light guide member is provided in a drawer tray that supports a process cartridge. Further, Patent Document 3 discloses an image forming apparatus in which a light source for static elimination is provided in a main body of the apparatus and a light guide member is provided in a process cartridge.

JP-A-2010-191328 Japanese Unexamined Patent Publication No. 2011-64711 JP 2015-194527

However, according to the techniques of Patent Documents 1 to 3, since the static elimination light source is provided in the apparatus main body, the distance from the static elimination light source to the light guide member becomes long. Therefore, it has been difficult to reduce the size of the image forming apparatus and the amount of light of the static elimination light source.

An object of the present invention is to provide an image forming apparatus in which a static elimination light source is arranged so that a distance from a static elimination light source to a light guide member is shortened.

The image forming apparatus of the present invention has a housing, a photosensitive drum, a light guide member that guides light for static elimination to the surface of the photosensitive drum, and a process cartridge that can be attached to and detached from the housing, and the photosensitive drum. It is provided with a belt unit facing the above, a light source for static elimination that emits light for static elimination of the photosensitive drum toward the light guide member, and a belt unit that can be attached to and detached from the housing.

According to the above configuration, by providing the static elimination light source on the belt unit arranged near the photosensitive drum, the distance from the static elimination light source to the light guide member is shortened as compared with the configuration in which the static elimination light source is provided on the housing. be able to. Therefore, the image forming apparatus can be miniaturized, and the amount of light for static elimination can be reduced.

In the image forming apparatus, the light guide member is a first light guide portion extending in the direction of the rotation axis of the photosensitive drum, is arranged so as to face the surface of the photoconductor drum, and is a surface of the photoconductor drum. A first light guide unit having an exit surface that irradiates light toward the light guide unit is connected to the first end of the first light guide unit in the direction of the rotation axis, and extends in a direction intersecting the rotation axis of the photosensitive drum. The second light guide unit, which has an incident surface that receives light from the static elimination light source and a reflecting surface that reflects the light received from the incident surface toward the inside of the first light guide unit. And, the static elimination light source may emit light toward the incident surface.

According to the above configuration, by arranging the static elimination light source so as to emit light in a direction intersecting the rotation axis direction of the photosensitive drum, the degree of freedom in arranging the static elimination light source in the belt unit is increased.

Further, in the above image forming apparatus, the process cartridge may have a tubular light-shielding rib surrounding the incident surface of the light guide member.

According to the above configuration, the light leaking from the gap between the incident surface and the static elimination light source is irradiated to the photosensitive drum by shielding the gap between the incident surface of the light guide member and the static elimination light source with a light shielding rib. Can be prevented.

Further, in the above image forming apparatus, the belt unit has a belt unit side connector on the lower surface that is electrically connected to the static elimination light source, and the housing is such that the belt unit is mounted on the housing. In some cases, it may have a housing-side connector to be connected to the belt unit-side connector.

According to the above configuration, the connector can also be attached / detached by the attachment / detachment operation of the belt unit.

Further, in the above image forming apparatus, the static elimination light source may be a light emitting diode.

According to the above configuration, the light source can be miniaturized.

According to the present invention, by providing the static elimination light source on the belt unit arranged near the photosensitive drum, the distance from the static elimination light source to the light guide member can be shortened as compared with the configuration in which the static elimination light source is provided on the housing. Can be done. Therefore, the image forming apparatus can be miniaturized, and the amount of light for static elimination can be reduced.

It is a central sectional view of the image forming apparatus of one Embodiment. It is sectional drawing of the image forming apparatus at the position BB of FIG. It is sectional drawing of the image forming apparatus at the position AA of FIG. It is a perspective view of a belt unit. It is a top view of the belt unit. FIG. 5 is a sectional view taken along the line CC of FIG. FIG. 5 is a cross-sectional view taken along the line DD of FIG. It is a perspective view of the light source unit for static elimination.

[Overall configuration of image forming apparatus]
The image forming apparatus 1 shown in FIG. 1 is an embodiment of an electrophotographic image forming apparatus according to the present invention, and is a tandem type color printer that forms an image of a plurality of colors on paper S.

In the following description, the left side in FIG. 1 is defined as the front side of the image forming apparatus 1, the right side in FIG. 1 is defined as the rear side of the image forming apparatus 1, and the front side of the paper in FIG. 1 is the right side of the image forming apparatus 1, in FIG. The back side of the paper surface is defined as the left side of the image forming apparatus 1. Further, the upper side and the lower side in FIG. 1 are defined as the upper side and the lower side of the image forming apparatus 1, respectively.

The image forming apparatus 1 includes a housing 2, a paper feed tray 10 that supports the paper S, and an image forming unit 5 that forms an image on the paper S.

The housing 2 is formed in a substantially rectangular parallelepiped shape, and houses the paper feed tray 10 and the image forming unit 5. A top cover 23 that can swing around the rotation fulcrum 23B at the rear end is provided at the upper end of the housing 2. The top cover 23 is formed with a paper output tray 23A that inclines downward from the front side to the rear side.

In the housing 2, a transport path P for the paper S from the paper feed tray 10 to the paper output tray 23A via the image forming unit 5 is configured. The housing 2 includes a paper feed roller 11, a separation roller 12, a separation pad 12A, a transport roller pair 13, and a resist roller pair 14.

The paper S supported by the paper feed tray 10 is separated one by one by the paper feed roller 11, the separation roller 12, and the separation pad 12A, and is sent out to the transport path P.

The paper S sent out to the transport path P is transported toward the image forming unit 5 by the transport roller pair 13 and the resist roller pair 14. The resist roller pair 14 restricts the movement of the tip of the paper S to be transported and temporarily stops the paper S, and then transports the paper S toward the image forming unit 5 at a predetermined timing.

The image forming unit 5 is arranged above the paper feed tray 10, and includes four process cartridges 50 arranged side by side in the front-rear direction and a belt unit 30. Each process cartridge 50 is detachably attached to the housing 2 and is provided corresponding to each color of black, yellow, magenta, and cyan, respectively.

The process cartridge 50 has a photosensitive drum 51 and a developing roller 52. The photosensitive drum 51 is formed in a substantially cylindrical shape with the left-right direction as the axial direction, and is rotatably supported by the process cartridge 50. The developing roller 52 extends in the left-right direction and is rotatably supported by the process cartridge 50. The developing roller 52 is in contact with the front upper portion of the photosensitive drum 51.

On the upper side of the photosensitive drum 51, an LED unit 53 that is arranged to face the photosensitive drum 51 and exposes the surface of the photosensitive drum 51 is provided. The LED unit 53 is supported by the top cover 23.

Further, the process cartridge 50 includes a supply roller 54, a scorotron type charger 55, a light guide member 56, a cleaner brush 57, and a process frame 58. The supply roller 54 supplies toner as a developing agent to the developing roller 52. The toner is housed above the developing roller 52 and the supply roller 54 in the process cartridge 50.

The scorotron type charger 55 is arranged facing the photosensitive drum 51 above and after the photosensitive drum 51. The light guide member 56 is a member that guides light for static elimination to the surface of the photosensitive drum 51, and is arranged below the scorotron type charger 55 so as to face the photosensitive drum 51. The cleaner brush 57 is arranged to face the photosensitive drum 51 between the light guide member 56 and the scorotron type charger 55. The process frame 58 is a frame that supports each member of the process cartridge 50, that is, supports the supply roller 54, the scorotron type charger 55, the light guide member 56, and the cleaner brush 57.

The belt unit 30 is arranged to face each other below the transport path P of the process cartridge 50. The belt unit 30 is detachably attached to the housing 2 for easy replacement. The belt unit 30 includes a belt 31, a drive roller 32, a driven roller 33, a transfer roller 34, a static elimination light source 35 (see FIG. 2), and a belt frame 36.

The belt 31 is arranged so as to face each other below the transport path P of the photosensitive drum 51. The belt 31 is hung between the drive roller 32 and the driven roller 33 arranged in front of the drive roller 32. The transfer rollers 34 are arranged at positions facing each photosensitive drum 51 sandwiching the belt 31.

The static elimination light source 35 is arranged at a position facing the incident surface 56A of the light guide member 56. The belt frame 36 is a frame that supports each member of the belt unit 30, that is, supports the belt 31, the drive roller 32, the driven roller 33, the transfer roller 34, and the static elimination light source 35.

In the image forming unit 5, the surface of the photosensitive drum 51 is uniformly charged by the scorotron type charger 55 and then selectively exposed by the LED unit 53 based on predetermined image data. As a result, an electrostatic latent image based on the image data is formed on the surface of the photosensitive drum 51.

On the other hand, the toner contained in the process cartridge 50 is positively charged between the supply roller 54 and the developing roller 52 and is supported on the surface of the developing roller 52. By supplying the toner carried on the developing roller 52 to the electrostatic latent image on the surface of the photosensitive drum 51, the toner image is supported on the surface of the photosensitive drum 51.

When the paper S conveyed toward the image forming unit 5 reaches the belt 31, it is conveyed by the belt 31 and sequentially passes between the belt 31 and each photosensitive drum 51. Then, the toner image on the surface of the photosensitive drum 51 is transferred to the paper S by the transfer bias applied to the transfer roller 34 when facing the paper S. In this way, the toner image carried by the photosensitive drum 51 is transferred to the paper S by the belt unit 30.

At this time, the toner that could not be completely transferred to the paper S may remain on the surface of the photosensitive drum 51. The residual toner remaining on the surface of the photosensitive drum 51 faces the light guide member 56 as the photosensitive drum 51 rotates. The residual toner facing the light guide member 56 is easily removed from the photosensitive drum 51 by removing the attached charge by the light from the static elimination light source 35. After that, the residual toner is removed by the cleaner brush 57. With this, the surface of the photosensitive drum 51 is completely cleaned, and the next page is ready for printing.

The belt 31 in the present embodiment is configured as a transport belt that conveys the paper S on which the toner image is transferred, but the toner image is transferred to the belt itself, and the toner image transferred to the belt is further transferred to the paper S. It is also possible to construct an intermediate belt that is transferred to the toner.

The paper S on which the toner image is transferred is conveyed to the fixing device 16 arranged on the downstream side of the image forming unit 5. The fixing device 16 includes a heating roller 17 and a pressure roller 18 that presses against the heating roller 17, and the paper S conveyed to the fixing device 16 passes between the heating roller 17 and the pressure roller 18. The toner image is heat-fixed.

The paper S on which the toner image is heat-fixed is conveyed downstream from the fixing device 16 in the transfer direction, further conveyed by the paper ejection roller 19, and ejected to the output tray 23A of the top cover 23.

The configuration for shortening the distance from the static elimination light source to the light guide member 56 in the image forming apparatus 1 will be described in detail below.

[Light guide member in process cartridge]
FIG. 2 is a cross-sectional view of the image forming apparatus 1 at the position BB of FIG. 3, and FIG. 3 is a sectional view of the image forming apparatus 1 at the position AA of FIG. In FIGS. 2 and 3, the cover that constitutes the appearance of the top cover 23 and the like is not shown.

The light guide member 56 is formed in a substantially L shape using glass or resin as a material, and has a first light guide portion 561 and a second light guide portion 562. The first light guide portion 561 is a long portion extending in the left-right direction, which is the direction of the rotation axis of the photosensitive drum 51, and is arranged so as to face the surface of the photosensitive drum 51. The surface of the first light guide unit 561 facing the photosensitive drum 51 is an exit surface 56B that irradiates light toward the surface of the photosensitive drum 51.

The second light guide unit 562 is connected to the left end of the first light guide unit 561 as an example of the first end in the left-right direction, and extends downward as an example of the direction intersecting the rotation axis of the photosensitive drum 51. is there. The lower end surface of the second light guide portion 562 is an incident surface 56A that receives light from the static elimination light source 35. Further, the connecting portion of the second light guide unit 562 with the first light guide unit 561 reflects the light received from the incident surface 56A into the second light guide unit 562 and reflected into the first light guide unit 561. The surface is 56C.

The light guide member 56 is arranged outside the process frame 58 by projecting a part of the second light guide portion 562 including the incident surface 56A downward from the bottom surface of the process frame 58, and the other parts are inside the process frame 58. Have been placed.

The process frame 58 has a tubular light-shielding rib 58A that surrounds the incident surface 56A. The light-shielding rib 58A extends below the incident surface 56A and is in contact with the upper surface of the belt frame 36. As a result, the gap between the incident surface 56A of the light guide member 56 and the static elimination light source 35 can be shielded by the light blocking rib 58A, and the light leaking from the gap between the incident surface 56A and the static elimination light source 35 is transmitted to the photosensitive drum 51. It can be prevented from being irradiated. The light-shielding rib 58A may be provided on the belt frame 36.

[Light source for static elimination in the belt unit]
4 is a perspective view of the belt unit 30, FIG. 5 is a plan view of the belt unit 30, FIG. 6 is a sectional view taken along the line CC of FIG. 5, FIG. 7 is a sectional view taken along the line DD of FIG. Is a perspective view of the static elimination light source unit 40.

The belt frame 36 of the belt unit 30 includes a left frame 361 that rotatably supports the left ends of the drive roller 32, the driven roller 33, and the transfer roller 34, and a right frame 362 that supports the right ends of the rollers. Further, the belt frame 36 is arranged in front of the driven roller 33 and has a front frame 363 that connects the left frame 361 and the right frame 362. The front frame 363 is provided with a handle 364 for making it easy to attach / detach the belt unit 30 to / from the housing 2.

The belt unit 30 has a static elimination light source unit 40 inside the left frame 361. The static elimination light source unit 40 has four static elimination light sources 35, four holders 37, a substrate 38, and a belt unit side connector 39.

The static elimination light source 35 is arranged directly below the incident surface 56A of the light guide member 56 inside the left frame 361. The size can be reduced by using an LED for the static elimination light source 35. The static elimination light source 35 emits light in a direction intersecting the rotation axis direction of the photosensitive drum 51, or upward in the present embodiment. By arranging the static elimination light source 35 so as to emit light in a direction intersecting the rotation axis direction of the photosensitive drum 51, the degree of freedom in arranging the static elimination light source 35 in the belt frame 36 is increased. The static elimination light source 35 may be supported by a frame provided separately from the belt frame 36 in the belt unit 30.

The holder 37 is a tubular member that surrounds the static elimination light source 35. The holder 37 extends above the static elimination light source 35 and is fitted in a hole 36A formed on the upper surface of the left frame 361. As a result, it is possible to prevent the light from the static elimination light source 35 from leaking into the left frame 361, and guide the light from the static elimination light source 35 to the incident surface 56A of the light guide member 56 through the hole 36A and the light shielding rib 58A. Can be done.

The substrate 38 is a substantially rectangular circuit board extending in the front-rear direction, and mounts the static elimination light source 35 and the holder 37. The substrate 38 is arranged inside the left frame 361 in parallel with the upper surface of the left frame 361, and is fixed to the left frame 361 with screws.

The belt unit side connector 39 is a connector mounted on the lower surface of the substrate 38 and electrically connected to each static elimination light source 35. The housing 2 is provided with a housing-side connector 21 that is connected to the belt unit-side connector 39 when the belt unit 30 is attached to the housing 2. The housing-side connector 21 is connected by a flexible substrate 22 to a main substrate (not shown) that controls the entire image forming apparatus 1.

By providing the belt unit side connector 39 on the lower surface of the substrate 38 and providing the housing side connector 21 at a position facing the belt unit side connector 39 of the housing 2, the belt unit side connector can be attached and detached by the belt unit 30 attachment / detachment operation. 39 can also be attached and detached. Therefore, the operation of attaching / detaching the belt unit side connector 39 becomes unnecessary, and the operability is improved.

The belt unit 30 is attached by lowering the front end portion with the rear end portion as a fulcrum while being inserted into the housing 2, and conversely, is removed by lifting the front end portion while being attached to the housing 2. Is done. Therefore, in order to allow the belt unit side connector 39 to be smoothly attached to and detached from the housing side connector 21, it is necessary to appropriately separate the belt unit side connector 39 from the rear end portion of the belt unit 30 as a fulcrum. Therefore, it is preferable that the belt unit side connector 39 is arranged near the center of the belt unit 30 in the front-rear direction.

According to the image forming apparatus 1 having such a configuration, by providing the static elimination light source 35 in the belt unit 30 arranged near the photosensitive drum 51, the static elimination light source 35 is provided for static elimination as compared with the configuration in which the static elimination light source 35 is provided in the housing 2. The distance from the light source 35 to the light guide member 56 can be shortened. Therefore, the image forming apparatus 1 can be miniaturized, and the static elimination light source 35 can be miniaturized. Further, by mounting the static elimination light source 35 on a board 38 different from the main board, the main board can be made smaller than the case where the static elimination light source 35 is mounted on the main board.

In the above embodiment, the tandem color printer has been described as an example of the image forming apparatus 1, but it can also be applied to a monochrome printer.

1 Image forming device 2 Housing 21 Housing side connector 30 Belt unit 31 Belt 35 Static elimination light source 39 Belt unit side connector 50 Process cartridge 51 Photosensitive drum 56 Light guide member 56A Incident surface 56B Exit surface 56C Reflective surface 58A Light shielding rib 561 First Light guide unit 562 Second light guide unit

Claims (5)

With the housing
A process cartridge that has a photosensitive drum and a light guide member that guides light for static elimination to the surface of the photosensitive drum and is removable from the housing.
A belt unit having a belt facing the photosensitive drum and a light source for static elimination that emits light for static elimination of the photosensitive drum toward the light guide member, and a belt unit that can be attached to and detached from the housing. Image forming device. The light guide member is
A first light guide portion extending in the direction of the rotation axis of the photosensitive drum, which is arranged so as to face the surface of the photosensitive drum and has an exit surface that irradiates light toward the surface of the photosensitive drum. Light guide and
An incident surface that is connected to the first end of the first light guide portion in the direction of the rotation axis and extends in a direction intersecting the rotation axis of the photosensitive drum, and receives light from the static elimination light source. And a second light guide portion having a reflecting surface that reflects the light received from the incident surface toward the inside of the first light guide portion.
Have,
The image forming apparatus according to claim 1, wherein the static elimination light source emits light toward the incident surface. The image forming apparatus according to claim 1 or 2, wherein the process cartridge has a tubular light-shielding rib that surrounds the incident surface of the light guide member. The belt unit has a belt unit side connector on the lower surface that is electrically connected to the static elimination light source.
The housing according to any one of claims 1 to 3, wherein the housing has a housing-side connector that is connected to the belt-unit-side connector when the belt unit is attached to the housing. The image forming apparatus described. The image forming apparatus according to any one of claims 1 to 4, wherein the static elimination light source is a light emitting diode.

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