JP7095538B2 - Drum unit - Google Patents

Description

The present invention relates to a drum unit including a light guide member that guides light for static elimination of the photosensitive drum to the surface of the photosensitive drum.

Conventionally, it is a static elimination device that irradiates a photosensitive drum with static elimination light to remove residual charge on the surface of the photosensitive drum to a predetermined potential or less. A light source that emits static elimination light and a rod-shaped guide extending along the axial direction of the photosensitive drum. A static elimination device composed of an optical member and a support member that holds both ends of the light guide member is known (see Patent Document 1). In this technique, the region not held by the support member of the light guide member is a static elimination region in which the light from the light guide member is applied to the photosensitive drum, and is a region held by the support member of the light guide member. Is a light-shielding region where the light from the light guide member is shielded by the support member.

Japanese Unexamined Patent Publication No. 2017-181878

By the way, in the prior art, in order to form a light-shielding region, it is necessary to provide a support member, that is, a dedicated light-shielding member at the end of the photosensitive drum.

The present invention has been made in view of the above background, and an object of the present invention is to provide a drum unit capable of blocking light from a light guide member toward an end portion of a photosensitive drum without providing a dedicated light blocking member. And.

In order to achieve the above-mentioned object, the drum unit of the present invention comprises a photosensitive drum, a light guide member that guides light for static elimination of the photosensitive drum to the surface of the photosensitive drum, and an axial direction of the photosensitive drum on the surface of the photosensitive drum. It includes a drum wiper having a removing portion that comes into contact with the end portion and removes the developer adhering to the surface of the photosensitive drum, and a frame member that supports the photosensitive drum, the light guide member, and the drum wiper.
In the drum wiper, the removing portion is arranged between the photosensitive drum and the light guide member, and the light from the light guide member is blocked by the axial end portion of the photosensitive drum.

According to such a configuration, since the removing portion also functions as a light-shielding member, the light directed from the light guide member to the end of the photosensitive drum without providing a dedicated light-shielding member between the photosensitive drum and the light guide member. Can be shielded from light. Further, since the removing portion blocks the light from the light guide member toward the end of the photosensitive drum in contact with the surface of the photosensitive drum, it is possible to suppress light from entering between the photosensitive drum and the removing portion. can.

In the above-mentioned drum unit, the drum wiper has a flexible sheet-like support member, and the support member is on the upstream side of the light guide member in the moving direction of the portion of the surface of the photosensitive drum facing the light guide member. It is possible to have a configuration having a first fixed end portion which is an end portion and is fixed to the frame member, and a first free end portion which is an end portion opposite to the first fixed end portion and is not fixed to the frame member. can.

According to this, the drum wiper can be easily attached to the frame member as compared with the case where both ends of the support member in the moving direction are fixed to the frame member.

In the above-mentioned drum unit, the support member may be arranged so as to have a gap between the support member and the light guide member.

According to this, since the support member can be bent toward the light guide member side, that is, the side away from the photosensitive drum, it is possible to prevent the removing portion from being pressed against the surface of the photosensitive drum more strongly than necessary. .. As a result, it is possible to further suppress the wear of the photosensitive layer due to contact with the removing portion of the drum wiper.

The above-mentioned drum unit includes a drum scraper that comes into contact with the axial end portion of the photosensitive drum and removes the developer adhering to the surface of the photosensitive drum, and the drum scraper is fixed to the frame member. It has a second fixed end portion and a second free end portion that is in contact with the end portion of the photosensitive drum in the axial direction and is not fixed to the frame member, and the second fixed end portion is the moving direction. In the light guide member, the light guide member may be fixed to the frame member on the same side as the first fixed end portion.

According to this, the drum unit is fixed as compared with the case where the first fixed end portion is fixed to one side in the moving direction and the second fixed end portion is fixed to the other side in the moving direction across the light guide member. It can have a simple structure.

In the above-mentioned drum unit, the support member is a sheet made of rectangular resin, one end in the longitudinal direction is the first fixed end, and the other end in the longitudinal direction is the first free end, which is removed. The portion is made of felt, foamed resin, non-woven fabric or woven fabric, and may be attached to the surface of the first free end portion facing the photosensitive drum.

According to this, the removing portion having high cleaning performance can be pressed against the surface of the photosensitive drum with an appropriate force by the support member. This makes it possible to satisfactorily remove the developer adhering to the surface of the photosensitive drum.

In the drum unit described above, the removal portion may be configured to be black.

According to this, since the light from the light guide member can be absorbed by the removing portion, it is possible to further suppress the light from hitting the end portion of the photosensitive drum.

In the above-mentioned drum unit, the frame member has a first wall provided along the light guide member on the downstream side of the light guide member in the moving direction of the portion of the surface of the photosensitive drum facing the light guide member, and has a removing portion. Can be configured such that the downstream end in the moving direction is in contact with the first wall or is located downstream of the upstream end in the moving direction of the first wall.

According to this, it is possible to suppress the leakage of light from the gap between the light guide member and the first wall, so that it is possible to further suppress the light from hitting the end portion of the photosensitive drum.

In the above-mentioned drum unit, a cleaning roller which is arranged adjacent to the light guide member on the downstream side of the light guide member in the moving direction and which comes into contact with the surface of the photosensitive drum to remove paper dust adhering to the surface of the photosensitive drum is provided. The first wall may be configured to be arranged between the light guide member and the cleaning roller.

According to this, it is possible to prevent the paper dust that has fallen off from the cleaning roller by the first wall from adhering to the light guide member.

In the drum unit described above, the first wall may be configured to be a film attached to a frame member.

According to this, since the first wall can be made thin, the drum unit can be made into a compact configuration. In particular, in a configuration including a cleaning roller, since the light guide member and the cleaning roller can be arranged closer to each other, it is possible to suppress an increase in the size of the photosensitive drum and to make the drum unit a compact configuration.

In the drum unit described above, the film may be configured to be white.

According to this, since the light directed from the light guide member toward the first wall can be reflected, it is possible to suppress the diffusion of the light and secure the amount of the light particularly hitting the portion excluding the end portion of the photosensitive drum. ..

In the above-mentioned drum unit, the frame member has a second wall provided along the light guide member on the upstream side of the light guide member in the moving direction of the portion of the surface of the photosensitive drum facing the light guide member, and has a removing portion. Can be configured such that the upstream end in the moving direction is located upstream of the downstream end in the moving direction of the second wall.

According to this, it is possible to suppress the leakage of light from the gap between the light guide member and the second wall, so that it is possible to further suppress the light from hitting the end portion of the photosensitive drum.

The above-mentioned drum unit includes a developing roller that supplies a developing agent to a photosensitive drum, a blade rubber portion that comes into contact with the surface of the developing roller, and a layer thickness regulating blade that has a blade body that supports the blade rubber portion. The rubber portion may have a notch at the end in the axial direction, and the removing portion may be arranged at a position overlapping the notch in the axial direction.

According to this, the developer adhering to the region overlapping the notch of the photosensitive drum can be efficiently removed by the removing portion, so that the developer adhering to the region overlapping the notch of the photosensitive drum adheres to the charger or the like. Can be suppressed.

The drum unit described above is a charger for charging the photosensitive drum, and may be configured to include a charger having a wire and a grid electrode provided between the wire and the photosensitive drum.

According to this, it is possible to effectively suppress the developer adhering to the region overlapping the notch portion of the photosensitive drum from adhering to the grid electrode.

In the above-mentioned drum unit, the frame member has a resin-made first frame member that supports the light guide member, the first frame member has a guide wall for guiding the seat, and the guide wall has the seat. It can be configured to have a guide surface that can be guided and an uneven shape formed on the surface on the back side of the guide surface.

According to this, since the portion of the frame member that supports the light guide member and the portion that guides the seat can be integrated, the drum unit can be made compact. Further, since the concave-convex shape is formed on the back surface of the guide surface, sink marks when the resin material is molded and shrunk can be suppressed, and the strength of the guide wall can be improved. Further, since the uneven shape is formed on the surface on the back side of the guide surface, the unevenness appearing on the guide surface can be reduced, so that the sheet can be satisfactorily guided by the guide surface.

In the drum unit described above, the light guide member has a light receiving surface for allowing light to enter one end in the axial direction, and the frame member has a second frame member that rotatably supports the photosensitive drum, and the second frame member. The frame member may be configured to have a hole for exposing the light receiving surface.

According to this, light can be introduced into the light guide member from a light source provided outside the drum unit.

According to the present invention, it is possible to block the light from the light guide member toward the end of the photosensitive drum without providing a dedicated light blocking member.

It is a figure which shows the schematic structure of the image forming apparatus provided with a drum unit. It is an enlarged view of the main part of a drum unit. It is an enlarged view around the photosensitive drum of a drum unit. It is a figure which shows the positional relationship in the axial direction of the photosensitive drum of a cleaning roller, a drum wiper, a drum scraper, a photosensitive drum, a developing roller, and a layer thickness regulation blade. It is a perspective view of a photosensitive drum, a light guide member, and a first support member. It is a side view which looked at the drum unit from the light receiving surface side of a light guide member. It is an enlarged view around the photosensitive drum of the drum unit which concerns on a modification.

Next, an embodiment of the invention will be described with reference to the drawings as appropriate. In this embodiment, the right side in FIG. 1 is "front", the left side is "rear", the front side is "left", and the back side is "right". Further, the upper side in FIG. 1 is referred to as "upper" and the lower side is referred to as "lower".

As shown in FIG. 1, the drum unit 6 according to the present embodiment is used in a state of being mounted on an image forming apparatus 1 that forms an image on a sheet S such as paper. The image forming apparatus 1 includes a main body housing 2, a sheet supply unit 3, an image forming unit 4 including a drum unit 6, and a sheet discharging unit 9.

The sheet supply unit 3 is provided under the main body housing 2 and includes a sheet supply tray 3A capable of accommodating a plurality of sheets S, and a sheet supply mechanism 3B. The sheet supply unit 3 separates the sheets S in the sheet supply tray 3A one by one by the sheet supply mechanism 3B and supplies them to the image forming unit 4.

The image forming unit 4 includes an exposure unit 5, a drum unit 6, a transfer unit 7, and a fixing unit 8.

The exposure unit 5 is arranged above the main body housing 2 and includes a plurality of light source devices (not shown), a polygon mirror, a lens, a reflecting mirror, and the like. The exposure unit 5 exposes the surface of the photosensitive drum 10 by scanning the light beam indicated by the alternate long and short dash line on the surface of the photosensitive drum 10 at high speed.

The drum unit 6 includes four photosensitive drums 10 arranged side by side in the front-rear direction, a charger 20 and a developer 30 arranged corresponding to each photosensitive drum 10, and a frame that supports the photosensitive drum 10 and the charger 20. It includes a member 100. The drum unit 6 can be attached to and detached from the main body housing 2 through an opening formed when the front cover 2A provided on the front portion of the main body housing 2 is opened.

The developer 30 is removable from the frame member 100, and includes a developing roller 31, a supply roller 32, a layer thickness regulating blade 33, and an accommodating portion 34 for accommodating a developer made of positively charged dry toner. , Agitator 35 and. The developer 30 supplies the developer in the accommodating portion 34 to the supply roller 32 while stirring by the agitator 35, and supplies the developer from the supply roller 32 to the developing roller 31. Then, the developer 30 causes the developer supplied to the developing roller 31 to enter between the developing roller 31 and the layer thickness regulating blade 33 as the developing roller 31 rotates, to form a thin layer having a constant thickness. It is supported on the developing roller 31. Details of the drum unit 6 will be described later.

The transfer unit 7 is arranged between the seat supply tray 3A and the drum unit 6, and has a drive roller 7A, a driven roller 7B, an endless transfer belt 7C stretched on the drive roller 7A and the driven roller 7B, and 4 It is equipped with two transfer rollers 7D. The outer surface of the transfer belt 7C is in contact with each photosensitive drum 10, and the transfer roller 7D is arranged inside the transfer belt 7C so as to sandwich the transfer belt 7C with the corresponding photosensitive drum 10.

The fixing unit 8 is arranged behind the drum unit 6 and the transfer unit 7, and includes a heating roller 8A for heating the sheet S and a pressure roller 8B for pressing the heating roller 8A.

The image forming unit 4 uniformly charges the surface of the photosensitive drum 10 by the charging device 20, and then exposes the surface of the photosensitive drum 10 with a light beam based on the image data from the exposure unit 5, thereby performing electrostatic latent on the photosensitive drum 10. Form an image. After that, the image forming unit 4 supplies the developer carried by the developing roller 31 to the electrostatic latent image formed on the photosensitive drum 10, thereby visualizing the electrostatic latent image and placing it on the photosensitive drum 10. Form a developer image.

After that, the image forming unit 4 conveys the sheet S supplied from the sheet supply unit 3 between the photosensitive drum 10 and the transfer roller 7D to which the negative transfer bias is applied, thereby placing the sheet S on the photosensitive drum 10. The formed developer image is transferred to the sheet S. Then, the image forming unit 4 heat-fixes the developer image by transporting the sheet S on which the developer image is transferred between the heating roller 8A and the pressure roller 8B, and forms an image on the sheet S. ..

The sheet discharging unit 9 includes a transport roller 9A and a discharging roller 9B. The sheet discharging unit 9 discharges the image-formed sheet S onto the sheet discharging tray 2B outside the main body housing 2 by the transport roller 9A and the discharging roller 9B.

As shown in FIG. 2, the drum unit 6 includes a frame member 100, a photosensitive drum 10, a charger 20, an replaceable developer 30, a light guide member 40, a drum cleaner 50, and a drum wiper 60. It is equipped with a drum scraper 70.

The photosensitive drum 10 is a member having a cylindrical raw tube 11 and a photosensitive layer 12 formed on the outer peripheral surface of the raw tube 11. The raw tube 11 is made of a conductive material such as metal, and is connected to the ground potential of the image forming apparatus 1 (see FIG. 1). The photosensitive layer 12 is formed of a positively charged organic photosensitive layer in which a charge generating material, an electron transporting material, a hole transporting material, and the like are dispersed in a resin such as polycarbonate.

The charger 20 is a device for charging the photosensitive drum 10, and is arranged so as to face the photosensitive drum 10. The charger 20 is a scorotron type charger having a wire 21 that causes a corona discharge and a grid electrode 22 provided between the wire 21 and the photosensitive drum 10. The charger 20 is configured to control the current flowing into the photosensitive drum 10 by the voltage applied to the grid electrode 22, thereby controlling the charging. Further, the charger 20 has a wire cleaner 23 that removes the developer adhering to the wire 21 by moving the charger 20 left and right along the wire 21.

The developer 30 is a device that supplies a developer from the developing roller 31 to the photosensitive drum 10. The developing roller 31 is located downstream of the position where the photosensitive drum 10 and the charger 20 face each other in the rotation direction of the photosensitive drum 10 with the developer 30 mounted on the frame member 100, and is the same as the photosensitive drum 10. The transfer roller 7D is arranged on the upstream side of the facing position and facing the photosensitive drum 10.

As shown in FIG. 3, the layer thickness regulating blade 33 has a blade main body 33A and a blade rubber portion 33B. The blade main body 33A is a member that supports the blade rubber portion 33B, and is made of a metal plate that is long on the left and right. One end of the blade body 33A in the lateral direction is fixed to the housing of the developer 30, and the blade rubber portion 33B is fixed to the surface of the other end in the lateral direction on the developing roller 31 side.

The blade rubber portion 33B is a portion that comes into contact with the surface of the developing roller 31, and is made of silicone rubber, urethane rubber, or the like. As shown in FIG. 4, the blade rubber portion 33B has a notch portion 33C at each end portion in the left-right direction corresponding to the axial direction of the photosensitive drum 10. The cutout portion 33C has a shape that is recessed from the upstream side to the downstream side (from the upper side to the lower side in FIG. 4) of the developing roller 31 in the rotational direction. Although only the right side portion of each member is shown in FIG. 4, the left side portion of each member has the same configuration as the right side portion.

Returning to FIG. 3, in the blade rubber portion 33B, the portion between the left and right notch portions 33C where the notch portion 33C is not formed comes into contact with the surface of the developing roller 31 on the surface. On the other hand, in the blade rubber portion 33B, the portion where the notch portion 33C is formed comes into contact with the surface of the developing roller 31 at the edge portion of the notch portion 33C. As a result, the developer supplied on the developing roller 31 is more likely to be scraped off at the portion where the notch 33C is formed, and is more likely to receive a strong force.

The light guide member 40 is a member that guides light for static elimination of the photosensitive drum 10 to the surface of the photosensitive drum 10. The light emitted from the light guide member 40 to the surface of the photosensitive drum 10 removes the electric charge remaining on the surface of the photosensitive drum 10 to a predetermined potential or less. The light guide member 40 is located downstream of the position where the photosensitive drum 10 and the transfer roller 7D face each other in the rotation direction of the photosensitive drum 10, and upstream of the position where the photosensitive drum 10 and the charger 20 face each other. It is arranged so as to face the photosensitive drum 10.

As shown in FIG. 5, the light guide member 40 (member with a dot hatch) is formed in a long rod shape on the left and right, and is arranged along the photosensitive drum 10. The light guide member 40 has a light receiving surface 41 and an emitting surface 42. The light receiving surface 41 is a surface for receiving the light LT from the light source 1L, and is provided on one end of the light guide member 40 in the axial direction of the photosensitive drum 10, specifically, on the right end surface. The emission surface 42 is a surface for emitting light for static elimination of the photosensitive drum 10 toward the surface of the photosensitive drum 10, and is provided so as to face the photosensitive drum 10.

The light source 1L is an LED (Light Emitting Diode), and is provided in the main body housing 2 of the image forming apparatus 1. Four light sources 1L are arranged side by side in the front-rear direction, and the drum unit 6 is provided so as to face the light receiving surface 41 of the corresponding light guide member 40 in a state of being mounted on the main body housing 2.

As shown in FIG. 3, the drum cleaner 50 is a device for removing paper dust adhering to the surface of the photosensitive drum 10. The drum cleaner 50 includes a cleaning roller 51, a recovery roller 52, a first scraping member 53, a second scraping member 54, and a storage portion 55.

The cleaning roller 51 is a roller that comes into contact with the surface of the photosensitive drum 10 and removes paper dust adhering to the surface of the photosensitive drum 10. Specifically, the cleaning roller 51 is configured to electrically adsorb and remove the paper dust adhering to the surface of the photosensitive drum 10 by applying a positive bias having a polarity opposite to the charging characteristics of the paper dust. ..

The cleaning roller 51 is located downstream of the position where the photosensitive drum 10 and the light guide member 40 face each other in the rotation direction of the photosensitive drum 10, and upstream of the position where the photosensitive drum 10 and the charger 20 face each other. It is arranged so as to face the photosensitive drum 10. Further, the cleaning roller 51 is specifically located on the downstream side of the light guide member 40 in the movement direction (hereinafter, simply referred to as “movement direction”) of the portion of the surface of the photosensitive drum 10 facing the light guide member 40. Is arranged above the light guide member 40 and adjacent to the light guide member 40.

The recovery roller 52 is a metal roller that comes into contact with the surface of the cleaning roller 51 and collects paper dust adhering to the surface of the cleaning roller 51.
The first scraping member 53 is a member that comes into contact with the surface of the recovery roller 52 and scrapes the paper dust collected on the surface of the recovery roller 52, and is made of a block-shaped sponge or the like.
The second scraping member 54 is a member whose tip comes into contact with the surface of the recovery roller 52 and scrapes the paper dust that could not be scraped by the first scraping member 53 from the surface of the recovery roller 52, and is a resin film. And so on.

The storage portion 55 is a portion for storing the paper dust scraped by the first scraping member 53 and the second scraping member 54. The storage portion 55 is formed by the frame member 100. Specifically, in the storage portion 55, the front / rear, left / right, and lower walls are formed by the first support member 110 described later of the frame member 100, and the upper wall is formed by the second support member 120 described later of the frame member 100. ing.

The frame member 100 is a member that supports the photosensitive drum 10, the light guide member 40, and the like. The frame member 100 includes a first support member 110 as a first frame member, a second support member 120, a third support member 130, and a pair of side wall members 140 as a second frame member (see FIG. 6; only one). (Illustrated). The first support member 110, the second support member 120, and the third support member 130 are provided so as to span the left and right side wall members 140.

The first support member 110 is a resin member that supports the light guide member 40 and the second scraping member 54, and is a guide wall 113 for guiding the first wall 111, the second wall 112, and the sheet S. And have.

The first wall 111 is a long wall on the left and right sides provided along the light guide member 40 on the downstream side of the light guide member 40 in the moving direction, specifically, on the upper side of the light guide member 40. The first wall 111 is arranged between the light guide member 40 and the cleaning roller 51. The first wall 111 is a resin film attached to the first support member 110 with an adhesive or the like. The film constituting the first wall 111 is white. The distance between the light guide member 40 and the cleaning roller 51 is smaller than the thickness of the wall (second wall 112, guide wall 113, etc.) of the first support member 110.

The second wall 112 is a long wall on the left and right provided along the light guide member 40 on the upstream side of the light guide member 40 in the moving direction, specifically, on the lower side of the light guide member 40. The second wall 112 is arranged between the light guide member 40 and the drum scraper 70. The second wall 112 is integrally formed with the first support member 110.

The guide wall 113 is a long wall on the left and right so as to face the transport belt 7C, and has a guide surface 113A capable of guiding the sheet S transported between the photosensitive drum 10 and the transfer roller 7D. There is. The guide surface 113A is a surface of the guide wall 113 facing the transport belt 7C, specifically, a lower surface of the guide wall 113, and extends back and forth and left and right along the upper surface of the transport belt 7C.

The guide wall 113 is formed with ribs 114 on the back surface 113B, which is the back surface of the guide surface 113A, that rises from the back surface 113B and extends substantially along the left and right sides, and further extends forward from the left and right ends. See also FIG. 5). By having such a rib 114, the guide wall 113 has an uneven shape on the back surface 113B. On the other hand, the guide surface 113A is a substantially flat surface without such an uneven shape. The guide wall 113 constitutes the lower wall of the storage portion 55 of the drum cleaner 50, and the rib 114 constitutes the front side and the left and right walls of the storage portion 55.

The second support member 120 is a resin member that rotatably supports the cleaning roller 51 and the recovery roller 52 and also supports the first scraping member 53. The second support member 120 is assembled to the first support member 110 to form a storage portion 55 with the first support member 110.
The third support member 130 is a resin member that supports the wire 21 and the grid electrode 22, and constitutes the housing of the charger 20.

As shown in FIG. 6, the side wall member 140 is a member that rotatably supports the photosensitive drum 10. Specifically, the side wall member 140 includes a sheet metal member (not shown) that rotatably supports the photosensitive drum 10 via a bearing member, and a resin cover member 142 arranged on the left and right outer sides of the sheet metal member so as to cover the sheet metal member. have.

The side wall member 140 has a plurality of through holes 143 formed in the cover member 142. The through hole 143 is a hole for exposing the light receiving surface 41 of the light guide member 40. When the drum unit 6 is mounted on the main body housing 2, the light receiving surface 41 of the light guide member 40 is arranged so as to face the light source 1L (see FIG. 5) via the through hole 143.

As shown in FIG. 3, the drum wiper 60 and the drum scraper 70 are members for removing the developer adhering to the axial end portion 13 (see FIG. 4) of the photosensitive drum 10 on the surface of the photosensitive drum 10.
The drum wiper 60 has a support member 61 and a removing portion 62.

The support member 61 is a flexible sheet-like member, and is made of a resin or the like capable of transmitting light from the light guide member 40. Furthermore, the support member 61 is a sheet made of a rectangular resin, and is elastically flexible and deformable. The support member 61 has a first fixed end portion 61A and a first free end portion 61B.

The first fixed end portion 61A is an end portion of the support member 61 on the upstream side of the light guide member 40 in the moving direction, specifically, an end portion on the lower side. Furthermore, the first fixed end portion 61A is one end portion in the longitudinal direction of the rectangle. The first fixed end portion 61A is attached to the second wall 112 with an adhesive or the like, and is thereby fixed to the first support member 110. In other words, the frame member 100 supports the drum wiper 60.

The first free end portion 61B is an end portion of the support member 61 opposite to the first fixed end portion 61A, that is, an upper end portion. Further, the first free end portion 61B is the other end portion in the longitudinal direction of the rectangle. The first free end portion 61B is not fixed to the frame member 100.

The removing portion 62 is a member that comes into contact with the end portion 13 (see FIG. 4) of the surface of the photosensitive drum 10 and wipes off the developer adhering to the surface of the photosensitive drum 10 to remove it, and is made of felt or the like. The removing portion 62 is attached to the surface of the support member 61 on the photosensitive drum 10 side of the first free end portion 61B, in other words, the surface of the first free end portion 61B facing the photosensitive drum 10 with an adhesive or the like. .. The removing portion 62 is black.

In the drum wiper 60, the removing portion 62 is arranged between the photosensitive drum 10 and the light guide member 40. As a result, the removing portion 62 shields the light from the light guide member 40 at the end portion 13 of the photosensitive drum 10. Specifically, the removing unit 62 shields light emitted from the left and right ends of the exit surface 42 of the light guide member 40 toward the left and right ends 13 of the photosensitive drum 10.

Therefore, as shown in FIG. 4, the surface of the photosensitive drum 10 has a light-shielding region A1 in which the light from the light guide member 40 is shielded by the light-shielding portion 62. Further, on the surface of the photosensitive drum 10, the region where the removing portion 62 does not contact, and more specifically, the region between the left and right removing portions 62 is the static elimination region A2 where the light from the light guide member 40 is irradiated. ..

Returning to FIG. 3, the first free end portion 61B of the support member 61 is arranged so as to have a gap between the support member 61 and the light guide member 40. That is, the first free end portion 61B is arranged in a state of being separated from the light guide member 40 so that the surface opposite to the surface to which the removal portion 62 is fixed does not come into contact with the light guide member 40.

The removing portion 62 is arranged in a state where the upper end portion 62A, which is the downstream end in the moving direction, is in contact with the first wall 111 directly or via the support member 61. Further, in the removing portion 62, the lower end portion 62B, which is the upstream end in the moving direction, is upstream of the upper end 112A, which is the downstream end of the tip surface of the second wall 112 in the moving direction, specifically. It is located on the lower side. In other words, the lower end portion 62B of the removing portion 62 extends below the upper end 112A of the second wall 112.

The drum scraper 70 is a member that comes into contact with the end portion 13 (see FIG. 4) of the surface of the photosensitive drum 10 and scrapes off the developer adhering to the surface of the photosensitive drum 10, and is made of a resin film or the like. .. The drum scraper 70 has a second fixed end portion 71 and a second free end portion 72. The second fixed end portion 71 is an end portion on the side far from the photosensitive drum 10, and is fixed to the first support member 110 with an adhesive or the like. The second free end portion 72 is an end portion on the side opposite to the second fixed end portion 71 and close to the photosensitive drum 10, and is arranged in a state where the tip is in contact with the end portion 13 on the surface of the photosensitive drum 10. There is. The second free end 72 is not fixed to the frame member 100.

The second fixed end 71 of the drum scraper 70 is fixed to the light guide member 40 on the same side as the first fixed end 61A of the drum wiper 60 to the first support member 110 in the moving direction. Specifically, both the first fixed end portion 61A and the second fixed end portion 71 are fixed to the first support member 110 under the light guide member 40. The first fixed end 61A is fixed to the lower surface of the second wall 112 of the first support member 110, and the second fixed end 71 is attached to the front end of the guide surface 113A near the base of the second wall 112. It is fixed.

As shown in FIG. 4, the removing portion 62 of the drum wiper 60 and the drum scraper 70 are provided corresponding to the left and right end portions 13 on the surface of the photosensitive drum 10, and are arranged so as to face the end portions 13 of the photosensitive drum 10. Has been done.

Further, the removing portion 62 and the drum scraper 70 are arranged at positions overlapping with the notch portion 33C formed in the blade rubber portion 33B of the layer thickness regulating blade 33 in the left-right direction. Specifically, the removing portion 62 and the drum scraper 70 are arranged at positions where the left and right widths are larger than the left and right widths of the notch portion 33C and overlap with the entire notch portion 33C in the left and right direction. In other words, the notch 33C is arranged within the width of the removing portion 62 and the drum scraper 70 in the left-right direction.

Further, the cutout portion 33C, the removing portion 62, and the drum scraper 70 are arranged outside the region PA in which the image of the maximum size sheet S that can be printed by the image forming apparatus 1 is formed in the left-right direction. On the other hand, the cutout portion 33C, the removing portion 62, and the drum scraper 70 are arranged at positions overlapping with the end SE of the maximum size sheet S in the left-right direction.

When attaching the drum wiper 60 and the drum scraper 70 to the frame member 100, first, the drum wiper 60 is attached to the frame member 100 before the photosensitive drum 10 is attached. Then, after the drum wiper 60 is attached to the frame member 100, the surface of the photosensitive drum 10 comes into contact with the removal portion 62 in a state where the support member 61 is bent so that the first free end portion 61B is brought close to the cleaning roller 51. The photosensitive drum 10 is attached to the frame member 100. After that, the drum scraper 70 is attached to the frame member 100.

Next, the action and effect of the drum unit 6 configured as described above will be described.
As shown in FIG. 3, when the developer is carried on the developing roller 31 in the developing device 30, the developing agent that has entered between the developing roller 31 and the portion where the notch 33C of the blade rubber portion 33B is formed is removed. The developing roller 31 and the edge portion of the notch 33C rub against each other strongly. As a result, the developer may be negatively charged, which has the opposite polarity to the charging characteristics, especially in a high temperature and high humidity environment. Then, when such a negatively charged developer is supplied onto the end portion 13 of the photosensitive drum 10 and moves to a position facing the charger 20, it is scattered by an air flow or the like generated by charging, and the wire 21 And there is a possibility that it will adhere to the grid electrode 22.

In this regard, according to the drum unit 6 of the present embodiment, the developer adhering to the end portion 13 of the photosensitive drum 10 can be removed by the drum scraper 70 or the drum wiper 60, and thus adheres to the end portion 13 of the photosensitive drum 10. It is possible to prevent the developed developer from moving to a position facing the charger 20. As a result, it is possible to suppress the developer from scattering during charging, and it is possible to suppress the developer from adhering to the wire 21 and the grid electrode 22.

On the other hand, in the configuration including the drum scraper 70 and the drum wiper 60, the tip of the drum scraper 70 and the removing portion 62 of the drum wiper 60 continue to be in contact with the end 13 of the photosensitive drum 10, so that the photosensitive drum 10 is exposed to light over time. The layer 12 may wear. When the photosensitive layer 12 is worn and the photosensitive layer 12 becomes thin, the surface potential of the photosensitive drum 10 is less likely to rise even when charged, and a positively charged developer is likely to adhere. Then, when a positively charged developer adheres to the end 13 of the photosensitive drum 10, the developer may be transferred to the left and right edges of a particularly large size sheet S to stain the sheet S.

In this regard, according to the drum unit 6 of the present embodiment, the light directed from the light guide member 40 toward the end portion 13 of the photosensitive drum 10 can be shielded by the removing portion 62, so that the end portion 13 of the photosensitive drum 10 is more than necessary. It is possible to suppress the static elimination. As a result, it is possible to prevent the photosensitive layer 12 from deteriorating at the end portion 13 of the photosensitive drum 10. By suppressing the deterioration of the photosensitive layer 12, it is possible to suppress the wear of the photosensitive layer 12 due to contact with the drum scraper 70 and the removing portion 62.

According to the present embodiment described above, the removing portion 62 of the drum wiper 60 is arranged between the photosensitive drum 10 and the light guide member 40 to block the light from the light guide member 40, whereby the removing portion 62 is guided. Since it also functions as a member that blocks light from the optical member 40, the light guide member 40 can be moved to the end portion 13 of the photosensitive drum 10 without providing a dedicated light blocking member between the photosensitive drum 10 and the light guide member 40. It can block the light that is heading. Further, since the removing portion 62 shields the light from the light guide member 40 toward the end portion 13 of the photosensitive drum 10 in contact with the surface of the photosensitive drum 10, light is emitted between the photosensitive drum 10 and the removing portion 62. It can be suppressed from entering.

Further, since the removing portion 62 is arranged between the photosensitive drum 10 and the light guide member 40, the photosensitive drum 10 and the light guide member 40 come into direct contact with each other when an impact is applied to the drum unit 6 from the outside. Can be suppressed. In particular, by forming the removing portion 62 from a material having a cushioning property such as felt, the removing portion 62 acts as a cushion, so that the photosensitive drum 10 can be satisfactorily protected.

Further, since the support member 61 of the drum wiper 60 is fixed to the frame member 100 at the first fixed end portion 61A and the first free end portion 61B is not fixed to the frame member 100, both ends of the support member in the moving direction are framed. The drum wiper 60 can be easily attached to the frame member 100 as compared with the case of fixing to the member.

Further, since the support member 61 is arranged so as to have a gap between the support member 61 and the light guide member 40, the support member 61 can be bent toward the light guide member 40 side, that is, the side away from the photosensitive drum 10. .. As a result, it is possible to prevent the removing portion 62 from being pressed against the surface of the photosensitive drum 10 more strongly than necessary, so that it is possible to further suppress the wear of the photosensitive layer 12 due to contact with the removing portion 62. ..

Further, since the second fixed end 71 of the drum scraper 70 is fixed to the frame member 100 on the same lower side as the first fixed end 61A of the drum wiper 60 with respect to the light guide member 40, for example, the light guide member is sandwiched. Therefore, the drum unit 6 can have a simple structure as compared with the case where the first fixed end portion is fixed to the upper side of the light guide member and the second fixed end portion is fixed to the lower side of the light guide member. ..

Further, the drum wiper 60 has a high cleaning performance because the removing portion 62 made of felt is attached to the first fixed end portion 61A of the support member 61 which is a sheet made of elastically flexible and deformable resin. The removing portion 62 can be pressed against the surface of the photosensitive drum 10 with an appropriate force by the support member 61. As a result, the developer adhering to the surface of the photosensitive drum 10 can be satisfactorily removed.

Further, since the removing portion 62 is black, the light from the light guide member 40 can be absorbed by the removing portion 62. As a result, it is possible to further suppress the light from hitting the end portion 13 of the photosensitive drum 10.

Further, since the upper end portion 62A of the removing portion 62 is in contact with the first wall 111, it is possible to suppress light from leaking from the gap between the light guide member 40 and the first wall 111. As a result, it is possible to further suppress the light from hitting the end portion 13 of the photosensitive drum 10.

Further, since the first wall 111 is arranged between the light guide member 40 and the cleaning roller 51, it is possible to prevent the paper dust that has fallen off from the cleaning roller 51 by the first wall 111 from adhering to the light guide member 40. be able to.

Further, since the first wall 111 is a film, the first wall 111 can be made thinner. As a result, the drum unit 6 can be made compact. In particular, in the configuration including the cleaning roller 51 as in the present embodiment, since the light guide member 40 and the cleaning roller 51 can be arranged closer to each other, it is possible to suppress the increase in size of the photosensitive drum 10 and make the drum unit 6 compact. Can be configured as such.

Further, since the film constituting the first wall 111 is white, it is possible to reflect the light from the light guide member 40 toward the first wall 111. As a result, it is possible to suppress the diffusion of light and secure the amount of light that particularly hits the portion of the photosensitive drum 10 other than the end portion 13.

Further, since the lower end portion 62B of the removing portion 62 is located below the upper end 112A of the second wall 112, it is possible to suppress light leakage from the gap between the light guide member 40 and the second wall 112. be able to. As a result, it is possible to further suppress the light from hitting the end portion 13 of the photosensitive drum 10.

Further, since the removing portion 62 is arranged at a position overlapping the notch portion 33C formed in the blade rubber portion 33B of the layer thickness regulating blade 33 in the left-right direction, the region overlapping the notch portion 33C of the photosensitive drum 10, that is, the photosensitive portion is photosensitive. The developer adhering to the end portion 13 of the drum 10 can be efficiently removed by the removing portion 62. As a result, it is possible to prevent the developer adhering to the end portion 13 of the photosensitive drum 10 from adhering to the charger 20 or the like.

In particular, when the charger 20 is a scorotron type charger having a grid electrode 22, the developer attached to the end portion 13 of the photosensitive drum 10 can be efficiently removed by the removing portion 62, so that the end of the photosensitive drum 10 can be efficiently removed. It is possible to effectively prevent the developer adhering to the portion 13 from adhering to the grid electrode 22 having no cleaner such as the wire cleaner 23.

Further, since the guide wall 113 for guiding the seat S is formed on the first support member 110 that supports the light guide member 40, the portion of the frame member 100 that supports the light guide member 40 and the seat S are guided. The portion can be integrated, and the drum unit 6 can be made into a compact configuration. Further, since the uneven shape is formed on the back surface 113B of the guide wall 113 by the ribs 114, sink marks when the resin material constituting the first support member 110 is molded and shrunk can be suppressed, and the guide wall 113 can be suppressed. The strength of the can be improved. Further, since the uneven shape is formed on the back surface 113B of the guide wall 113, the unevenness appearing on the guide surface 113A can be reduced to make a substantially flat surface. Since it is difficult to get caught, the seat S can be satisfactorily guided by the guide surface 113A.

Further, since the side wall member 140 of the frame member 100 is formed with a through hole 143 for exposing the light receiving surface 41 of the light guide member 40, light is emitted from the light source 1L provided outside the drum unit 6 to the light guide member 40. You can put it in.

Although one embodiment of the invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately modified and carried out.
For example, in the above embodiment, in the removing portion 62, the upper end portion 62A is in contact with the first wall 111, but the removal portion 62 is not limited to this.

That is, as shown in FIG. 7, in the removing portion 62, the upper end portion 62A is downstream of the lower end 111A, which is the end surface on the photosensitive drum 10 side of the first wall 111, which is the upstream end in the moving direction. May be configured to be located on the upper side. In other words, the upper end portion 62A of the removing portion 62 may be configured to extend above the lower end 111A of the first wall 111. Even with such a configuration, it is possible to suppress light leakage from the gap between the light guide member 40 and the first wall 111, so that the light hits the left and right end portions 13 of the photosensitive drum 10 more. It can be suppressed.

The removal portion 62 has a configuration in which the upper end portion 62A does not reach the lower end 111A of the end surface of the first wall 111 on the photosensitive drum 10 side, that is, the upper end portion 62A is located below the lower end 111A. May be good. Further, the removing portion 62 may have a configuration in which the lower end portion 62B does not reach the upper end 112A of the front end surface of the second wall 112, that is, the lower end portion 62B is located above the upper end 112A.

Further, in the above embodiment, the support member 61 of the drum wiper 60 is arranged with a gap between the support member 61 and the light guide member 40, but the present invention is not limited to this, and the support member is in contact with the light guide member. It may be arranged by. Further, in the above-described embodiment, the support member 61 has a configuration in which the first fixed end portion 61A is fixed to the frame member 100 and the first free end portion 61B is not fixed to the frame member 100, but the present invention is limited to this. However, for example, both ends of the support member in the moving direction may be fixed to the frame member.

Further, in the above embodiment, the removing portion 62 of the drum wiper 60 is black, but the present invention is not limited to this, and a color other than black may be used as long as it can block the light from the light guide member. Further, in the above-described embodiment, the removing portion 62 is fixed to the frame member 100 via the supporting member 61, but the present invention is not limited to this. It may be fixed to. Further, the material of the removed portion is not limited to felt, and may be a foamed resin such as a sponge, a non-woven fabric, or a woven fabric.

Further, in the above embodiment, the first wall 111 of the frame member 100 is white, but the present invention is not limited to this, and a color other than white may be used. Further, in the above embodiment, the first wall 111 is a film attached to the frame member 100, but the present invention is not limited to this, and for example, the first wall is the same as the second wall 112 of the above embodiment. It may be a wall integrally formed with the frame member.

Further, in the above embodiment, the scorotron type charger 20 is exemplified as the charging device for charging the photosensitive drum 10, but the present invention is not limited to this. For example, the charging device may be a corotron type charging device having no grid electrode. Further, the charging device may be a charging roller or the like.

Further, in the above-described embodiment, the drum unit 6 is provided with the drum scraper 70, but the present invention is not limited to this, and the drum unit 6 may be configured not to be provided with the drum scraper.

Further, in the above embodiment, as the image forming apparatus in which the drum unit according to the invention is used, an image forming apparatus 1 provided with a plurality of photosensitive drums 10 and capable of color printing is exemplified, but the present invention is not limited thereto. For example, the image forming apparatus may be an image forming apparatus having only one photosensitive drum and capable of monochrome printing only. Further, the image forming apparatus may be a printer, or may be a multifunction device or a copying machine provided with a document reading device such as a flatbed scanner.

Further, in the above-described embodiment, the drum unit 6 for color printing provided with a plurality of photosensitive drums 10 is exemplified as the drum unit, but the drum unit is not limited thereto. For example, the drum unit may be a drum unit for monochrome printing, a drum cartridge, a process cartridge, or the like, which is provided with only one photosensitive drum.

In addition, the elements described in the above-described embodiments and modifications can be combined and implemented as appropriate.

6 Drum unit 10 Photosensitive drum 13 End 20 Charger 21 Wire 22 Grid electrode 31 Development roller 33 Layer thickness regulation blade 33A Blade body 33B Blade rubber part 33C Notch 40 Light guide member 41 Light receiving surface 51 Cleaning roller 60 Drum wiper 61 Support member 61A 1st fixed end 61B 1st free end 62 Removal part 62A Upper end 62B Lower end 70 Drum scraper 71 2nd fixed end 72 2nd free end 100 Frame member 110 1st support member 111 1st wall 112 2nd Wall 112A Upper end 113 Guide wall 113A Guide surface 113B Back side 140 Side wall member 143 Through hole S sheet

Claims (15)

With a photosensitive drum,
A light guide member that guides light for static elimination of the photosensitive drum to the surface of the photosensitive drum, and
A drum wiper having a removing portion for removing the developer adhering to the surface of the photosensitive drum in contact with the axial end portion of the photosensitive drum.
The photosensitive drum, the light guide member, and the frame member that supports the drum wiper are provided.
The drum wiper is a drum unit in which the removing portion is arranged between the photosensitive drum and the light guide member, and light from the light guide member is shielded at an axial end portion of the photosensitive drum. .. The drum wiper has a flexible sheet-like support member.
The support member is an end portion on the upstream side of the light guide member in the moving direction of a portion of the surface of the photosensitive drum facing the light guide member, and is a first fixed end portion fixed to the frame member. The drum unit according to claim 1, further comprising a first free end portion that is an end portion opposite to the first fixed end portion and is not fixed to the frame member. The drum unit according to claim 2, wherein the support member is arranged so as to have a gap between the support member and the light guide member. A drum scraper is provided, which is provided with a drum scraper that comes into contact with the axial end of the photosensitive drum on the surface of the photosensitive drum and removes the developer adhering to the surface of the photosensitive drum.
The drum scraper has a second fixed end portion fixed to the frame member and a second free end portion that is in contact with the axial end portion of the photosensitive drum and is not fixed to the frame member. Have and
2. Claim 2 or claim 3, wherein the second fixed end portion is fixed to the frame member on the same side as the first fixed end portion with respect to the light guide member in the moving direction. The drum unit described in. The support member is a sheet made of a rectangular resin, one end in the longitudinal direction is the first fixed end portion, and the other end in the longitudinal direction is the first free end portion.
Any of claims 2 to 4, wherein the removing portion is made of felt, foamed resin, non-woven fabric or woven fabric, and is attached to the surface of the first free end portion facing the photosensitive drum. The drum unit according to item 1. The drum unit according to any one of claims 1 to 5, wherein the removing portion is black. The frame member has a first wall provided along the light guide member on the downstream side of the light guide member in a moving direction of a portion of the surface of the photosensitive drum facing the light guide member.
The removal portion is characterized in that the downstream end in the moving direction is in contact with the first wall or is located downstream of the upstream end in the moving direction of the first wall. The drum unit according to any one of claims 1 to 6. A cleaning roller is provided which is arranged adjacent to the light guide member on the downstream side of the light guide member in the moving direction and which comes into contact with the surface of the photosensitive drum to remove paper dust adhering to the surface of the photosensitive drum. ,
The drum unit according to claim 7, wherein the first wall is arranged between the light guide member and the cleaning roller. The drum unit according to claim 7, wherein the first wall is a film attached to the frame member. The drum unit according to claim 9, wherein the film is white. The frame member has a second wall provided along the light guide member on the upstream side of the light guide member in a moving direction of a portion of the surface of the photosensitive drum facing the light guide member.
Any of claims 1 to 10, wherein the removing portion has an upstream end in the moving direction located upstream of the downstream end of the second wall in the moving direction. The drum unit according to item 1. A developing roller that supplies a developing agent to the photosensitive drum, and
A layer thickness regulating blade having a blade rubber portion that comes into contact with the surface of the developing roller and a blade body that supports the blade rubber portion is provided.
The blade rubber portion has a notch at the end in the axial direction, and the blade rubber portion has a notch.
The drum unit according to any one of claims 1 to 11, wherein the removing portion is arranged at a position overlapping the notch portion in the axial direction. The drum unit according to claim 12, wherein the drum unit is a charger for charging the photosensitive drum, and includes a charger having a wire and a grid electrode provided between the wire and the photosensitive drum. The frame member has a first frame member made of resin that supports the light guide member.
The first frame member has a guide wall for guiding the seat, and has a guide wall.
The one according to any one of claims 1 to 13, wherein the guide wall has a guide surface capable of guiding the sheet and an uneven shape formed on the surface on the back side of the guide surface. Drum unit. The light guide member has a light receiving surface for allowing light to enter one end in the axial direction.
The frame member has a second frame member that rotatably supports the photosensitive drum.
The drum unit according to any one of claims 1 to 14, wherein the second frame member has a hole for exposing the light receiving surface.

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