JP3645560B2 - Cleaning unit - Google Patents

Description

  The present invention is applied to an image forming apparatus that transfers a toner image formed on an outer periphery of an image carrier to form an image on a sheet, and removes residual toner and paper dust attached to the outer periphery of the image carrier. Regarding the cleaning unit.

  Conventionally, in order to transport paper (including recording media such as OHP) to an image forming unit during image formation in an image forming apparatus, paper is fed to the image forming unit from a paper feed cassette disposed inside the apparatus main body. There are two methods: a paper feeding method that feeds the image forming unit from a manual paper feed tray disposed outside the apparatus main body.

The sheets stored in the sheet feeding cassette and the manual sheet feeding tray are selectively fed one by one at the time of image formation, and then conveyed to an image forming unit through a sheet conveying path to form an image. Here, when the sheets are fed one by one, the sheets are fed one by one by the separating member. Therefore, a talc member (a bleaching agent, an extender, etc., whose main component is analogized with S _i O ₂ ), which is a paper powder contained in the paper, is separated from the paper by friction between the paper and the rolling member. This paper dust is charged by friction or the like of the transport roller and the like, and adheres and accumulates on the outer periphery of each transport roller arranged on the paper transport path and the photosensitive member (image carrier) provided in the image forming unit. It has caused a decline in quality.

  For example, as shown in FIG. 6, the paper dust P adhering to the outer peripheral portion of the photoconductor 31 is transferred to the paper by the cleaning unit 35 after the toner image formed on the outer peripheral portion of the photoconductor 31 is transferred to the paper. It is removed together with the residual toner remaining on the outer periphery. The cleaning unit 35 is disposed on the outer peripheral portion of the photoconductor 31 on the downstream side in the rotation direction of the photoconductor 31 indicated by the arrow in FIG. 6 from the position where the toner image formed on the outer peripheral portion of the photoconductor 31 is transferred to the paper. The unit main body having the opening 35a is provided with a cleaning blade 35c and a toner fall prevention sheet 35e.

  The opening 35a collects the residual toner and the like scraped off in the cleaning unit 35. A part of the cleaning blade 35 c comes into contact with the outer peripheral portion of the photoconductor 31 and scrapes off residual toner and paper powder P adhering to the outer peripheral portion of the photoconductor 31. The toner fall prevention sheet 35e prevents residual toner and the like that has been scraped off from being collected from the opening 35a and falling to the paper conveyance path or the like.

  At this time, the toner with good fluidity is separated from the member such as the cleaning blade 35c that contacts the outer peripheral portion of the photoreceptor 31 and collected from the opening 35a. However, the paper powder P is separated due to poor fluidity. It is difficult to deposit on a member such as the cleaning blade 35c that comes into contact with the outer periphery of the photoreceptor 31.

Further, when a predetermined amount of paper dust P is deposited, the paper dust P is peeled off from the deposited member, and a part of the paper dust P is collected from the opening 35a. It will mix in the developing tank etc. which are arrange | positioned at the outer peripheral part of 31. When the paper dust P is mixed in the developing tank, the difference in charging characteristics between the toner and the paper dust (S _i O ₂ ) inhibits the normal charging of the toner, promotes the generation of uncharged toner, reduces the image quality, Image blur occurs. In particular, as shown in FIG. 6, the paper dust P peeled off from the cleaning blade 35c is likely to fall and accumulate on the toner fall prevention sheet 35e, so that the opening area of the opening 35a is narrowed by the accumulated paper dust P. The collecting ability of residual toner and paper dust P will be reduced. Further, since the toner fall prevention sheet 35e is located upstream of the cleaning blade 35c in the rotation direction of the photosensitive member 31, paper dust P is likely to accumulate on the contact portion with the outer peripheral portion of the photosensitive member 31 and its periphery. Then, the accumulated paper powder P is peeled off and falls onto the paper transport path or the paper on which the toner image is transferred, so that the image quality is lowered.

  Therefore, in recent image forming apparatuses, a cleaning roller having a dynamic friction coefficient larger than the dynamic friction coefficient of the feed roller and the surface of the rolling member in contact with the feed roller is brought into contact with the outer peripheral portion of the feed roller and the surface of the rolling member, and the dynamic friction coefficient There is one that removes paper dust and the like adhering to the outer peripheral portion of the feed roller and the surface of the rolling member due to the difference (for example, see Patent Document 1). In the configuration of Patent Document 1, paper dust or the like attached to the outer peripheral portion of the cleaning roller is removed by a cleaning blade that contacts the outer peripheral portion of the cleaning roller.

Also, a cleaning device that collects residual toner disposed on the outer periphery of the photoconductor is provided with a capture brush in contact with the outer periphery of the photoconductor, and a voltage is applied to the capture brush to apply to the outer periphery of the photoconductor. Some remove the adhering paper dust (see, for example, Patent Document 2).
JP 11-106073 A JP 2000-81819 A

  However, in the configuration of the above-described Patent Document 1, even if the cleaning unit is arranged in a state where the paper dust is not charged, the removal effect is not perfect and the removal of the paper dust is not sufficient. In addition, since a new cleaning roller must be provided, the cost is increased and the apparatus main body is enlarged.

  Further, in the configuration of the above-described Patent Document 2, it is possible to capture the charged paper dust attached to the outer peripheral portion of the photosensitive member by the capturing brush, but the capturing brush that contacts the outer peripheral portion of the photosensitive member. In addition to causing deterioration of the photoconductor (because the applied voltage for removing paper dust is close to the saturation charge potential of the photoconductor) by applying a voltage to the image, there is a problem in the image formation of the next transported paper. Occur.

  An object of the present invention is to provide a cleaning unit that efficiently removes paper dust adhering to the outer periphery of the photoconductor without damaging the outer periphery of the photoconductor while removing residual toner.

  In order to solve the above problems, the present invention has the following configuration.

(1) A unit main body that is disposed on the downstream side of the position where the toner image is transferred to the paper in the rotation direction of the image carrier and has an opening facing the outer periphery of the image carrier is provided on the outer periphery of the image carrier. A cleaning blade that scrapes off residual toner adhering thereto, and a toner fall prevention that is a sheet whose longitudinal direction is parallel to the axial direction of the image carrier and upstream of the opening of the unit body in the rotational direction of the image carrier A cleaning unit that collects residual toner scraped off by the cleaning blade into the unit body from the opening,
One end portion of the toner drop preventing sheet is attached to the seat mounting member secured to the units main body, the other end portion of said toner drop prevention sheet contacts the outer peripheral portion of the image bearing member, and, in the axial direction Set to parallel,
The sheet mounting member has a free length from one end portion to the other end portion of the toner fall prevention sheet that is less than a portion of the outer peripheral portion of the image carrier facing a portion where the amount of accumulated paper powder is small. towards the portion facing the large portion of the paper dust amount of retention of the outer peripheral portion is characterized that you have been formed to be longer.

In this configuration, the toner fall prevention sheet is set so that the other end portion thereof is parallel to the axial direction of the image carrier while being attached to the sheet attachment member at one end portion. Further, the free length from one end portion to the other end portion of the toner fall prevention sheet is less than the portion of the outer peripheral portion of the image carrier facing the portion where the paper dust stays less than the amount of paper dust remaining in the outer peripheral portion of the image carrier. It is formed so that the part which opposes the part with much is longer.
On the other hand, the paper dust is separated from the paper when the stored paper is transported from the paper feeding cassette or the like to the position where the toner image is transferred, and the paper is removed one by one by a separating member or the like. Therefore, the paper is transported in a state in which paper dust adheres to a portion that comes into contact with the separating member. Further, since the paper dust is charged by friction with the conveyance roller or the like during the conveyance of the paper, it adheres to the outer periphery of the image carrier when the toner image is transferred to the outer periphery of the image carrier. For this reason, the amount of paper dust adhering to the outer periphery of the image carrier is different in the axial direction of the image carrier.

  Further, since the paper powder has low fluidity, the paper powder scraped off by the cleaning blade easily accumulates on the toner fall prevention sheet. Further, since the toner fall prevention sheet is in contact with the outer peripheral portion of the image carrier, paper dust is likely to be deposited on the contact portion of the toner fall prevention sheet with the outer peripheral portion of the image carrier and the periphery thereof. For this reason, the amount of paper dust deposited on the toner fall prevention sheet in the longitudinal direction corresponds to the amount of paper dust retained on the outer periphery of the opposing image carrier.

  The toner fall prevention sheet vibrates due to the vibration caused by the driving of a conveying screw or the like provided in the cleaning unit.

Therefore, the free length of the portion of the toner fall prevention sheet facing the portion where the paper dust retention amount is large in the outer peripheral portion of the image carrier is free of the portion facing the portion where the paper dust retention amount is small in the outer periphery of the image carrier. Since this is longer than the length, the amplitude of the vibration of the portion of the toner fall prevention sheet facing the portion where the paper dust retention amount is large is larger than the amplitude of the portion of the toner fall prevention sheet facing the portion where the paper dust retention amount is small. growing.
As a result, the paper dust deposited on the portion of the toner fall prevention sheet that opposes the portion where the paper dust retention amount is large is likely to be peeled off by the vibration of the toner fall prevention sheet at a location with a large amplitude. Therefore, the paper dust does not accumulate on the toner fall prevention sheet and peels off instead of forming a large lump of paper dust, and rides on the flow of wind caused by the rotation of the image carrier, and the paper dust is more than the toner fall prevention sheet. It flows into the cleaning unit from the opening located downstream in the rotational direction.
In addition, since the other end portion of the toner fall prevention sheet attached to the sheet attachment member is set to be parallel to the axial direction of the image carrier, the toner fall prevention sheet is connected to the outer peripheral portion of the image carrier. Contact properly. Therefore, the paper dust and residual toner scraped off by the cleaning blade are not received by the toner fall prevention sheet and do not fall.
( 2 ) The stored sheets are taken out one by one by a separating member and conveyed to a position where a toner image is transferred,
The free length of the portion part of the toner drop preventing sheet opposite to the outer peripheral portion of the image bearing member adjacent to the contact portion of the sheet in contact with said separating member, not close to the contact portion of the sheet in contact with said separating member image It characterized by being longer than the free length of the portion part of the toner drop preventing sheet opposite to the outer peripheral portion of the bearing member.

  In this configuration, the free length of the portion of the toner fall prevention sheet that faces the outer peripheral portion of the image carrier adjacent to the contact portion of the paper that contacts the separation member is close to the contact portion of the paper that contacts the separation member. Since it is longer than the free length of the portion of the toner fall prevention sheet that faces the outer peripheral portion of the image carrier, the portion of the toner fall prevention sheet that faces the portion of the image carrier that has a large amount of paper dust retention The free length is longer than the free length of the portion of the toner fall prevention sheet that faces the portion of the outer peripheral portion of the image carrier where the amount of paper dust retention is small. This is because the contact location of the paper that contacts the whirling member is a location where paper dust is generated, so the amount of paper dust staying at the outer peripheral portion of the image carrier adjacent to the contact location is greater than at other locations. It is.

  Therefore, the free length of the portion of the toner fall prevention sheet that opposes at a portion where the more accurate amount of paper dust stays in the outer peripheral portion of the image carrier is long.

( 3 ) The toner fall prevention sheet is a resin film and is charged with a polarity opposite to the charging characteristics of the toner.

  In this configuration, the toner fall prevention sheet is formed of a resin film having a charging characteristic opposite to that of the residual toner. Accordingly, the residual toner and paper dust that are electrically attached to the outer periphery of the image carrier are attracted to the toner fall prevention sheet due to the charging characteristics, so that the toner fall prevention sheet is attached to the outer periphery of the image carrier. Residual toner and paper dust are likely to adhere.

  Further, since the toner fall prevention sheet is made of a flexible resin film, the outer peripheral portion of the image carrier that is in contact with the toner fall prevention sheet is hardly damaged.

  According to the present invention, the following effects can be obtained.

(1) Use the sheet mounting member to place the free length of the portion of the toner fall prevention sheet opposite to the portion where the paper powder stays in the outer peripheral portion of the image carrier with a small amount of paper dust stay in the outer periphery of the image carrier. By making the length longer than the free length of the portion facing the toner, the amplitude of the vibration of the portion facing the portion where the paper dust retention amount of the toner fall prevention sheet is large is set to the portion where the paper dust retention amount of the toner fall prevention sheet is small. It can be made larger than the amplitude of the opposing part.
As a result, the paper dust deposited on the portion of the toner fall prevention sheet that faces the portion where the amount of paper dust staying is large can be easily peeled off by the vibration of the sheet having a large amplitude. For this reason, the paper dust continues to accumulate on the toner fall prevention sheet, peels off without becoming a large lump, and rides on the flow of wind generated by the rotation of the image carrier, and thus in the rotational direction of the image carrier rather than the toner fall prevention sheet. Since it can be made to flow into the cleaning unit from the opening of the unit body located on the downstream side, the paper dust can be efficiently collected at the portion where the paper dust is likely to accumulate.

In addition, since the other end is set to be parallel to the axial direction of the image carrier, it can be properly brought into contact with the outer peripheral portion of the image carrier, and the paper dust scraped by the cleaning blade and the residual The toner can be received by the toner fall prevention sheet.
( 2 ) An image in which the free length of the portion of the toner fall prevention sheet facing the outer peripheral portion of the image carrier adjacent to the contact portion of the paper that contacts the separation member is not close to the contact portion of the paper that contacts the separation member By making it longer than the free length of the portion of the toner fall prevention sheet facing the outer peripheral portion of the carrier, the portion of the toner fall prevention sheet facing the portion with a large amount of paper dust retention on the outer periphery of the image carrier The free length can be made longer than the free length of the portion of the toner fall prevention sheet that faces the portion of the outer periphery of the image carrier where the amount of paper dust retention is small.

  As a result, it is possible to increase the free length of the portion of the toner fall prevention sheet that faces a more accurate portion where the amount of paper dust stays in the outer peripheral portion of the image carrier, so that the paper dust on the toner fall prevention sheet is accumulated. Paper dust can be collected more efficiently at the easy part.

( 3 ) By configuring the toner fall prevention sheet with a resin film having a charging characteristic opposite to that of the residual toner, the residual toner and paper powder that are electrically attached to the outer periphery of the image carrier are Since the toner fall prevention sheet can be attracted to the toner fall prevention sheet, the residual toner and paper dust adhered to the outer periphery of the image carrier are easily attached to the toner fall prevention sheet from the outer periphery of the image carrier and can be easily removed. Further, since the toner fall prevention sheet is made of a resin film, it is possible to prevent the outer peripheral portion of the image carrier from being damaged.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus to which a cleaning unit according to an embodiment of the present invention is applied. The image forming apparatus 100 as the main body apparatus of the present invention has a copier mode, a printer mode, and a FAX mode as image forming modes for forming an image on a sheet (including a recording medium such as an OHP). Selected, and duplex printing is possible.

  The image forming apparatus 100 includes a document reading unit 10, a paper feeding unit 20, an image forming unit 30, a paper discharge unit 40, an operation panel unit and a control unit (not shown). The document reading unit 10 is disposed on the upper part of the apparatus main body, and includes a platen glass 11, a document placing tray 12, a scanner optical system 13, and the like. The scanner optical system 13 includes a light source 14, reflection mirrors 15 a to 15 c, an optical lens 16, and a CCD (Charge Coupled Device) 17. The light source 14 irradiates light on a document placed on the platen glass 11 or a document transported on the document transport path R from the document placing tray 12. The plurality of reflecting mirrors 15 a to 15 c reflect the reflected light from the document and guide it to the optical lens 16. The optical lens 16 collects the reflected light guided by the reflection mirrors 15 a to 15 c and guides it to the CCD 17. The CCD 17 photoelectrically converts the collected reflected light.

  The paper feeding unit 20 is disposed at the lower part of the apparatus main body, and includes a paper feeding cassette 21, a manual feed tray 22, a paper feeding roller 23, a separating member 24, and the like. The paper feed tray 21 and the manual feed tray 22 place paper to be fed to the paper transport path S during image formation. The paper feed roller 23 rotates and conveys the paper stored in the paper feed tray 21 and the like to the separating member 24. The separating member 24 includes a feed roller 24a, a plate member 24b, and the like, and conveys the sheet conveyed by the sheet feeding roller 23 to the sheet conveying path S one sheet at a time when the sheet is conveyed in an overlapping manner. The feed roller 24a is in contact with the surface of the plate member 24b having a lower friction coefficient than the outer peripheral portion, and when the sheet is conveyed from the sheet feed roller 23 in a superimposed manner, one sheet on the feed roller 24a side is fed. Only the paper is transported to the paper transport path S. For example, when two sheets of paper are conveyed from the paper feed roller 23, the sheet on the side in contact with the plate member 24b becomes stationary on the surface of the plate member 24b due to friction with the plate member 24b. Only the sheet on the side in contact with the outer peripheral portion of the roller 24a is conveyed to the sheet conveying path S by friction with the feed roller 24a and rotation of the feed roller 24a.

  The image forming unit 30 is disposed on the side of the manual feed tray 22 below the document reading unit 10, and includes a laser scanning unit (hereinafter referred to as LSU) 37, a photoconductor 31 that is an image carrier of the present invention, and a fixing device 36. A charger 32, a developing device 33, a transfer device 34, and a cleaning unit 35 are arranged around the photoconductor 31 in this order along the arrow Y direction that is the rotation direction of the photoconductor 31. .

  The paper discharge unit 40 is disposed above the paper feed tray 21 and includes a paper discharge roller 41, a paper discharge tray 42, and the like. The paper discharge roller 41 discharges the paper transported on the paper transport path S to the paper discharge tray 42. Further, the paper discharge roller 41 is capable of reversible rotation. When image formation is performed on both sides of the paper, the paper that has been transported on the paper transport path S after chucking the paper on which surface image formation has been completed, The sheet rotates in the direction opposite to the rotation direction for discharging the sheet to the sheet conveying path S ′. As a result, the front and back surfaces of the sheet are reversed, the back surface faces the photoreceptor 31, and the toner image is transferred to the back surface. The paper discharge tray 42 stores the paper that has been discharged from the paper discharge roller 41 and has undergone image formation. Note that the separation member 24 according to the embodiment of the present invention is disposed so as to face a central portion of a conveyed sheet in a direction orthogonal to the sheet conveyance direction. The control unit controls the overall operation of the image forming apparatus 100 described above.

  When copying an image of a document on a sheet in the copier mode, after placing the document to be copied on the platen glass 11 or the document placing tray 12 of the document reading unit 10, each input key provided on the operation panel unit is pressed. Then, settings such as the number of prints and print magnification are entered, and a start key (not shown) is pressed to start the copy operation.

  When the start key is pressed, the image forming apparatus 100 rotates the paper feed roller 23 and feeds the paper to the paper transport path S. The fed paper is conveyed to a registration roller 51 provided on the paper conveyance path S.

  The leading end of the sheet conveyed to the registration roller 51 in the conveyance direction is aligned with the toner image formed on the outer peripheral portion of the photoreceptor 31 to be transferred to the sheet, so that it is parallel to the axial direction of the registration roller 51. It is chucked by the registration roller 51 so as to become.

  The image data read by the document reading unit 10 is subjected to image processing under conditions input using an input key or the like, and then transmitted to the LSU 37 as print data. The LSU 37 forms an electrostatic latent image by irradiating the outer periphery of the photoreceptor 31 charged to a predetermined potential by the charger 32 with laser light based on the image data via a polygon mirror and various lenses (not shown). To do. Thereafter, the toner adhering to the surface of the MG roller 33a provided in the developing device 33 is attracted and adhered to the outer peripheral portion of the photoconductor 31 according to the potential gap of the outer peripheral portion of the photoconductor 31, and the electrostatic latent image Is visualized.

  Thereafter, the registration roller 51 aligns the sheet chucked by the registration roller 51 with the toner image formed on the outer periphery of the photoreceptor 31, and the sheet is placed between the photoreceptor 31 and the transfer device 34. Transport. Next, the toner image on the outer periphery of the photoconductor 31 is transferred to the paper using a transfer roller (not shown) provided in the transfer device 34. The paper on which the transfer of the toner image has been completed is melted and fixed by applying heat and pressure when passing through the fixing device 36, and is discharged onto the paper discharge tray 42 by the paper discharge roller 41.

  Residual toner, paper dust, and the like adhering to the outer peripheral portion of the photoreceptor 31 after the toner image is transferred to the paper are collected by the cleaning unit 35.

  FIG. 2 is an enlarged cross-sectional view of a part of an image forming unit provided in an image forming apparatus to which a cleaning unit according to an embodiment of the present invention is applied. As shown in FIG. 2, the cleaning unit 35 is formed in the housing 35 b so that the opening 35 a faces the outer peripheral portion of the photoreceptor 31. The cleaning unit 35 includes a cleaning blade 35c, a conveying screw 35d, and a toner fall prevention sheet 35e.

The cleaning blade 35c has one end side in a direction orthogonal to the longitudinal direction parallel to the axial direction of the photoconductor 31 fixed near the upper edge of the opening 35a, and the other end facing the one end side is the outer peripheral portion of the photoconductor 31. The remaining toner and paper dust on the outer periphery of the photosensitive member 31 are scraped off with a predetermined contact force. The conveyance screw 35d is rotatably supported inside the housing 35b, and conveys residual toner and paper dust scraped off from the outer peripheral portion of the photoreceptor 31 from the inside of the housing 35b to an external collection toner storage box (not shown). Toner drop prevention sheet 35e has one end in a direction orthogonal to a longitudinal direction parallel to the axial direction of the photosensitive body 31 in the vicinity of the lower edge of the opening 35a is fixed, a resin film of the charging characteristics of the toner and opposite polarity Has been. The toner fall prevention sheet 35e has the other end portion opposite to the one end portion which is the fixed is in contact with the outer peripheral portion of the photoconductor 31. Further, the toner fall prevention sheet 35e prevents residual toner and paper dust scraped off from the outer peripheral portion of the photoreceptor 31 from dropping or leaking to the outside from the opening 35a.

  The sheet peeling claw 38 is disposed between the transfer device 34 and the cleaning unit 35 on the outer peripheral portion of the photoreceptor 31, and the sheet on which the toner image is transferred at a portion where the transfer device 34 and the photoreceptor 31 are opposed to each other is provided on the photoreceptor 31. Peel from.

  Here, the toner fall prevention sheet 35e is formed of a resin film having a charging characteristic opposite to that of the toner because the residual toner and paper dust that are electrically attached to the outer periphery of the photosensitive member are prevented from dropping due to the charging characteristic. This is because the residual toner and paper powder adhering to the outer peripheral portion of the photoreceptor can be easily attached to and removed from the outer peripheral portion of the photoreceptor because the toner can be attracted to the sheet. Moreover, it is because it comprises using a resin film and prevents the outer peripheral part of a photoconductor from being damaged. The thickness of the toner fall prevention sheet 35e is preferably 0.05 to 0.01 mm. This is because if the thickness is too thick, the outer peripheral portion of the photoreceptor 31 is easily damaged, and if the thickness is too thin, the shape of the toner fall prevention sheet 35e cannot be maintained.

FIG. 3 is an enlarged view of a part of the appearance of the cleaning unit according to the embodiment of the present invention. As shown in FIG. 3, the toner fall prevention sheet 35e has one end in the direction perpendicular to the longitudinal direction is fixed to the housing 35b by a seat mounting member 35f. The sheet attachment member 35f has a central portion in the longitudinal direction on the toner fall prevention sheet 35e side cut out.

Therefore, as shown in FIGS. 4A and 4B, the position where the one end portion is fixed in the direction orthogonal to the longitudinal direction of the toner fall prevention sheet 35e is the central portion in the longitudinal direction and the other portions. Are different from each other.

Therefore, the toner drop prevention sheet 35e illustrated in FIG. 4 (a) free length L1 from one end to the other end in the longitudinal direction central portion of the longitudinal direction of the toner fall prevention sheet 35e shown in FIG. 4 (b) longer than the free length L2 from one end to the other end in a portion other than the central portion. Further, the cleaning unit 35 vibrates by driving the conveying screw 35d and the like as indicated by arrows in FIGS. 4 (a) and 4 (b). Therefore, the amplitude of the central portion in the longitudinal direction of the toner fall prevention sheet 35e having the free length L1 longer than the free length L2 is larger than the portion other than the central portion in the longitudinal direction of the toner fall prevention sheet 35e.

  Here, most of the paper dust is generated due to friction between the paper and the separating member 24 when the sheet conveyed from the sheet feeding tray 21 or the like is spread by the separating member 24 during image formation. In the embodiment of the present invention, the separating member 24 comes into contact with the paper at the central portion in the sub-scanning direction of the paper, so that paper dust is generated from the central portion of the paper in the sub-scanning direction.

  Further, since paper dust is charged by friction with a conveyance roller (not shown) during the conveyance of the paper, it adheres to the outer peripheral portion of the photoconductor 31 when the toner image on the outer peripheral portion of the photoconductor 31 is transferred.

  Accordingly, the portion where the amount of paper dust staying in the outer peripheral portion of the photoconductor 31 is a portion facing the central portion in the sub-scanning direction of the paper, and the paper dust adhering to the outer peripheral portion of the photoconductor 31 in the axial direction of the photoconductor 31. The amount is different.

  On the other hand, since the paper powder has low fluidity, the paper powder P scraped off by the cleaning blade 35 easily accumulates on the toner fall prevention sheet 35e as shown in FIG. Further, since the toner fall prevention sheet 35e is in contact with the outer peripheral portion of the photosensitive member 31, paper dust is likely to be deposited on the contact portion of the toner fall prevention sheet 35e with the outer peripheral portion of the photosensitive member 31 and its periphery. For this reason, the amount of paper powder P deposited on the toner fall prevention sheet 35e in the longitudinal direction corresponds to the amount of paper powder retention at the outer peripheral portion of the opposing photoreceptor 31.

  As described above, the free length L1 at the central portion in the longitudinal direction of the toner fall prevention sheet 35e facing the portion where the paper powder retention amount is large in the outer peripheral portion of the photoconductor 31 is set longer than the free length L2 and vibrates. As shown in FIG. 5B, the paper powder can be easily peeled off from the toner fall prevention sheet 35e by vibration and collected from the opening 35a.

  Here, the paper dust can be collected from the opening 35a located on the downstream side in the arrow Y direction with respect to the arrangement position of the toner fall prevention sheet 35e because the wind in the arrow Y direction is caused by the rotation of the photoconductor 31 in the arrow Y direction. This is because it occurs. That is, the paper dust P is peeled off from the toner fall prevention sheet 35e without becoming a large lump due to vibration, and thus flows into the opening 35b by riding on this wind flow. Therefore, the paper dust can be efficiently collected at the portion of the toner fall prevention sheet 35e where the paper dust easily accumulates at the portion facing the paper dust retention location.

  Further, as described above, the free lengths L1 and L2 of the toner fall prevention sheet 35e correspond to the central portion in the sub-scanning direction of the paper, which is the contact position of the paper that contacts the paper-rolling member 24 where the paper dust P occurs. As a result, the free length L1 of the portion of the toner falling sheet 35e that opposes the portion of the outer peripheral portion of the photoreceptor 31 where the amount of accumulated paper dust is more accurate can be increased, and the paper in the toner falling prevention sheet 35e can be increased. The paper powder P can be collected more efficiently at the portion where the powder P tends to accumulate.

Further, by configuring the lengths of the free lengths L1 and L2 using the sheet attachment member 35f, the contact portion of the toner fall prevention sheet 35e with the outer peripheral portion of the photoreceptor 31 due to the configuration of the free lengths L1 and L2. Since the shape of the other end portion on the side is not limited, the other end portion is formed in parallel with the longitudinal direction of the paper, so that the outer peripheral portion of the photoconductor 31 can be appropriately brought into contact with the cleaning blade. The paper dust P and residual toner scraped off by 35c can be received by the toner fall prevention sheet 35e.

  In the embodiment of the present invention, the paper dust staying portion in the outer peripheral portion of the photoconductor 31 is the central portion in the axial direction of the photoconductor 31. However, the present invention is not limited to this, and the paper dust of the paper is scattered. What is necessary is just to let the part which opposes the location generate | occur | produced by the member 24 be a paper dust retention location.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus to which a cleaning unit according to an embodiment of the present invention is applied. FIG. 3 is an enlarged cross-sectional view of a part of an image forming unit provided in an image forming apparatus to which the cleaning unit is applied. It is the figure which expanded a part of external appearance of the cleaning unit. FIG. 4 is a cross-sectional view of a toner fall prevention sheet provided in the cleaning unit. FIG. 3 is an enlarged cross-sectional view of a part of an image forming unit provided in an image forming apparatus to which the cleaning unit is applied. It is sectional drawing to which some image forming parts with which the conventional image forming apparatus was equipped was expanded.

Explanation of symbols

24-Rolling member 30-Image forming unit 31-Photoconductor 35-Cleaning unit 35a-Opening 35c-Cleaning blade 35d-Conveying screw 35e-Toner fall prevention sheet 35f-Sheet mounting member 100-Image forming device P-Paper dust

Claims (3)

Residue that adheres to the outer peripheral portion of the image carrier on the unit main body, which is disposed downstream of the position where the toner image is transferred to the paper in the rotation direction of the image carrier and has an opening facing the outer peripheral portion of the image carrier. A cleaning blade that scrapes off the toner, a toner fall prevention sheet that is a sheet whose longitudinal direction is parallel to the axial direction of the image carrier and is located upstream of the opening of the unit body in the rotational direction of the image carrier; In the cleaning unit for collecting the residual toner scraped off by the cleaning blade into the unit body from the opening,
One end portion of the toner drop preventing sheet is attached to the seat mounting member secured to the units main body, the other end portion of said toner drop prevention sheet contacts the outer peripheral portion of the image bearing member, and, in the axial direction Set to parallel,
The sheet mounting member has a free length from one end portion to the other end portion of the toner fall prevention sheet that is less than a portion of the outer peripheral portion of the image carrier facing a portion where the amount of accumulated paper powder is small. cleaning unit towards the portion facing the large portion of the paper dust amount of retention of the outer peripheral portion is characterized that you have been formed to be longer. The stored paper is picked up one by one by a separating member and conveyed to a position where a toner image is transferred,
An image of the free length of the portion of the toner fall prevention sheet facing the outer peripheral portion of the image carrier that is in proximity to the contact portion of the sheet that contacts the separating member is not adjacent to the contact portion of the sheet that contacts the separating member. The cleaning unit according to claim 1, wherein the free length of the portion of the toner fall prevention sheet facing the outer peripheral portion of the carrier is longer than the free length. The toner drop preventing sheet is a resin film, a cleaning unit according to claim 1, characterized that you charged to the charging characteristics of the toner and opposite polarity.

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