JP2017219551A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can prevent the occurrence of accumulation of toner at the ends of a recovery roller.SOLUTION: An image forming apparatus 1 comprises: an image carrier 7 on the surface of which toner images are formed; a rotating brush 41 that is in contact with the surface of the image carrier 7 after transfer of the toner images to a transfer sheet to collect a residual substance attached to the surface; a recovery roller 42 that removes the residual substance collected by the rotating brush 41; and a cleaning blade 43 that scrapes off the residual substance recovered by the recovery roller 42. When the maximum width of a toner image forming area 7c of the image carrier 7 is A, the total width of the rotating brush 41 is B, the total width of the recovery roller 42 is C, and the total width of the cleaning blade 43 is D, the relational expression A<B<D<C is established.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus including a cleaning device that removes toner from an image carrier.

  In the electrophotographic image forming apparatus, the toner remaining on the image carrier after the toner image is transferred to the transfer paper is removed by a cleaning device. In an image forming apparatus compatible with full color, an intermediate transfer belt is used as an image carrier.

  In the intermediate transfer belt cleaning device, the toner is mechanically and electrically swept away from the surface of the intermediate transfer belt by a rotating brush, and the toner is moved from the rotating brush to the collecting roller by electrostatic force, and the toner adhering to the collecting roller is removed. The intermediate transfer belt is cleaned by scraping it off with a cleaning blade. In order to reliably recover the toner remaining on the intermediate transfer belt and prevent the problem of toner contamination, the width of the rotating brush, recovery roller, and cleaning blade should be appropriate for the width of the toner image formation area on the intermediate transfer belt. Therefore, it is necessary not to form a toner reservoir or the like.

  For example, Patent Document 1 proposes an image forming apparatus that defines the width of a rotating brush ≧ the width of a collection roller ≧ the width of a cleaning blade.

JP 2009-237269 A

  However, in the image forming apparatus disclosed in Patent Document 1, toner collected from the rotary brush to the collection roller remains at the both ends of the collection roller without being scraped off by the cleaning blade, so that toner accumulation occurs at the end of the collection roller. There is a risk of doing.

  Accordingly, in consideration of the above circumstances, the present invention appropriately sets the widths of the rotating brush, the collection roller, and the cleaning blade with respect to the width of the toner image forming area on the intermediate transfer belt, thereby the toner on the end of the collection roller. An object of the present invention is to provide an image forming apparatus capable of preventing the occurrence of accumulation.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes an image carrier that is rotatably provided and has a toner image formed on a surface thereof, and the image carrier after the toner image is transferred onto a transfer sheet. A rotating brush that contacts the surface and collects residues adhering to the surface, a collecting roller that removes residues collected on the rotating brush, and a cleaning that scrapes off the residues collected on the collecting roller A maximum width of a toner image forming area of the image carrier, A full width of the rotating brush, B full width of the collection roller, and full width of the cleaning blade. When D, the relational expression of A <B <D <C is established.

  By adopting such a configuration, the toner scattered at the end of the toner image forming area on the image carrier can be collected on the rotating brush before reaching the collecting roller. Since the toner collected in this way can be scraped off with a cleaning blade with sufficient margin in the width direction, it is possible to prevent toner from being collected at the end of the collection roller.

  In the image forming apparatus of the present invention, the total width B of the rotating brush is 4 mm or more longer than the maximum width A of the toner image forming area, and each end in the width direction of the rotating brush is the width of the toner image forming area. It is good also as the feature which is spaced apart 2 mm or more from each direction end part.

  By adopting such a configuration, toner scattered from the end of the toner image forming area can be reliably collected on the rotating brush before reaching the collection roller, thus preventing toner collection on the collection roller. be able to.

  In the image forming apparatus according to the aspect of the invention, the rotating brush, the collection roller, and the cleaning blade are supported by a support member, and the support member is provided so as to be movable toward or away from the image carrier. It may be characterized by being.

  By adopting such a configuration, when the rotating brush changes with time and the toner collecting performance from the image carrier decreases, the toner from the image carrier can be obtained by bringing the rotating brush closer to the image carrier. The collection performance can be improved.

  In the image forming apparatus of the present invention, the rotating brush and the collection roller rotate in the opposite direction at the same rotation speed, and the rotating brush contacts the rotation direction of the image carrier from the counter direction. The rotation speed of the rotating brush and the collection roller can be changed so as to be faster than the rotation speed of the image carrier.

  By adopting such a configuration, when the cleaning performance of the image carrier is lowered, the toner collection performance from the image carrier can be improved by increasing the rotational speed of the rotating brush and the collection roller. .

  In the image forming apparatus according to the aspect of the invention, the image carrier may be an endless intermediate transfer belt, and may include a plurality of image forming units arranged in tandem along the rotation direction of the intermediate transfer belt. good.

  By adopting such a configuration, it is possible to prevent toner collecting on the collecting roller in the cleaning device for the intermediate transfer belt in the full-color image forming apparatus.

  According to the present invention, the toner scattered at the end of the toner image forming area on the image carrier can be collected on the rotating brush before reaching the collecting roller, and further collected on the collecting roller from the rotating brush. Since the toner can be scraped off with a cleaning blade with sufficient margin in the width direction, it is possible to prevent toner accumulation from occurring at the end of the collecting roller.

1 is a schematic diagram illustrating an outline of a color printer according to an embodiment of the present invention. 1 is a front view showing an intermediate transfer belt cleaning device in a color printer according to an embodiment of the present invention. FIG. FIG. 4 is a diagram illustrating a width relationship among a toner image forming region, a rotating brush, a collection roller, and a cleaning blade in a color printer cleaning device according to an embodiment of the present invention. 4A and 4B are views showing the positional relationship between the toner image forming area, the rotating brush, the collection roller, and the end of the cleaning blade in the color printer cleaning apparatus according to the embodiment of the present invention. 4A shows a positional relationship in which toner accumulation is prevented, and FIG. 4B shows a positional relationship in which toner accumulation occurs.

  Hereinafter, an image forming apparatus according to an embodiment of the present disclosure will be described with reference to the drawings.

  First, the overall main configuration of the color printer 1 (image forming apparatus) will be described with reference to FIG. FIG. 1 is a schematic diagram showing an outline of a printer according to an embodiment of the present invention. Hereinafter, the front side of the paper surface in FIG. 1 will be referred to as the front side (front side) of the color printer 1, and the left and right directions will be described with reference to the direction when the printer 1 is viewed from the front.

  The color printer 1 includes a box-shaped printer body 2. A paper feed unit 4 that feeds transfer paper from the paper feed cassette 3 is provided at the lower part of the printer main body 2, and a paper discharge tray 5 is provided at the upper part of the printer main body 2. Inside the printer main body 2, a toner container 6 that accommodates toners of different colors (for example, four colors of magenta, cyan, yellow, and black) is disposed above. Below the toner container 6, an intermediate transfer belt 7 (image carrier) is installed between the driving roller 8R and the driven roller 8L so as to rotate counterclockwise in FIG. A secondary transfer portion 9 is formed at one end (right end in the figure) of the intermediate transfer belt 7, and a cleaning device 10 is provided at the other end. Below the intermediate transfer belt 7, four image forming units 12 corresponding to the colors of the toner are arranged in a tandem shape along the rotation direction of the intermediate transfer belt 7.

  Each image forming unit 12 is rotatably provided with a photosensitive drum 13. Around the photosensitive drum 13, a charging device 14, a developing device 15, a transfer roller 16, a cleaning device 17, and a charge eliminating device 18 are sequentially arranged along the rotation direction of the photosensitive drum 13. Further, an exposure device 21 composed of a laser scanning unit (LSU) is disposed below each image forming unit 12. A fixing device 22 is provided above the secondary transfer unit 9, and a paper discharge unit 23 facing the paper discharge tray 5 is provided above the fixing device 22.

  Further, inside the printer body 2, there is provided a transfer paper transport path 24 that extends from the paper feed unit 4 to the paper discharge unit 23 through the secondary transfer unit 9 and the fixing device 22.

  Next, an image forming operation of the printer 1 having such a configuration will be described. When image data is input from a computer or the like connected to the printer 1, an image forming operation is executed as follows.

  First, after the surface of the photosensitive drum 13 is charged by the charging device 14, the photosensitive drum 13 is exposed according to the image data by the laser light (see the chain line P in FIG. 1) from the exposure device 21. An electrostatic latent image is formed on the surface of the photosensitive drum 13. The electrostatic latent image is developed into a corresponding color toner image by the developing device 15. The toner image is primarily transferred onto the surface of the intermediate transfer belt 7 by the transfer roller 16. Each image forming unit 12 sequentially repeats the above operation, whereby a full-color toner image is formed on the intermediate transfer belt 7. The toner and charge remaining on the photosensitive drum 13 are removed by the cleaning device 17 and the charge eliminating device 18.

  On the other hand, the transfer paper taken out from the paper feed cassette 3 or the manual feed tray (not shown) by the paper feed unit 4 is conveyed to the secondary transfer unit 9 in synchronization with the above-described image forming operation, and the secondary transfer unit. 9, the full-color toner image on the intermediate transfer belt 7 is secondarily transferred to the transfer paper. The toner remaining on the intermediate transfer belt 7 is removed by the cleaning device 10. The transfer paper on which the toner image has been secondarily transferred is conveyed downstream in the conveyance path 24 and enters the fixing device 22 where the toner image is fixed on the transfer paper. The transfer paper on which the toner image is fixed is discharged from the paper discharge unit 23 onto the paper discharge tray 5.

  Next, the cleaning device 10 will be described with reference to FIGS. 2 and 3. FIG. 2 is a front view of the cleaning device, and FIG. 3 is a diagram illustrating a width relationship among a toner image forming region, a rotating brush, a collection roller, and a cleaning blade of the cleaning device.

  As shown in FIG. 2, the cleaning device 10 is disposed to face the driven roller 8 </ b> L on which the intermediate transfer belt 7 is installed. The intermediate transfer belt 7 is, for example, provided with an elastic layer 7b and a coating layer (not shown) in this order on the surface layer side of a resin base layer 7a. The elastic layer 7b is made of, for example, urethane rubber. The surface layer is made of, for example, PTEF (polytetrafluoroethylene). A is the maximum width of the toner image forming area on the intermediate transfer belt 7.

  Further, in the rotational direction of the intermediate transfer belt 7, a fixed brush 31 is provided on the upstream side of the cleaning device 10, and a tension roller 32 is provided on the downstream side of the cleaning device 10.

  The cleaning device 10 includes a support member 40, a rotary brush 41 that collects toner from the surface of the intermediate transfer belt 7 supported by the support member 40, a collection roller 42 that collects toner from the rotary brush 41, and a collection It has a cleaning blade 43 that contacts the roller 42 and scrapes off the toner, a seal member 44 that contacts the collection roller 42 and prevents toner leakage, and a screw member 45 that recovers the scraped toner.

  The support member 40 is a box-shaped member having an opening on the right side, and is disposed so that the opening faces the driven roller 8L, and is supported by the printer main body 2 so as to be movable toward or away from the driven roller 8L. Yes. As a mechanism for supporting the support member 40 movably, for example, an eccentric cam is provided so as to contact the support member 40, and the support member 40 is moved in the direction of the driven roller 8L by rotating the eccentric cam. Can do.

  The rotating brush 41 rotates counterclockwise in FIG. 2 so as to come in contact with the surface of the intermediate transfer belt 7 from the counter direction with respect to the rotational movement direction of the intermediate transfer belt 7 (counterclockwise direction in FIG. 2). Supported as possible. The rotation speed of the rotary brush 41 is variable, and is set to be about 20% higher than the rotation speed of the intermediate transfer belt 7. The rotating brush 41 is formed of a fur brush using brush fibers made of conductive resin such as conductive polyester or conductive nylon. Let B be the entire width of the rotating brush 41.

  The collection roller 42 is in contact with the rotary brush 41 on the downstream side in the rotational movement direction of the rotary brush 41 with respect to the contact portion C1 between the rotary brush 41 and the intermediate transfer belt 7, and rotates in the clockwise direction of FIG. The brush 41 is supported so as to rotate at the same rotational speed. Note that the rotation speed of the collection roller 42 is variable according to the rotation speed of the rotary brush 41. The collection roller 42 includes, for example, a metal base material 42a such as aluminum, and a surface layer 42b formed by anodizing the surface of the base material 42a. The total width of the collection roller 42 is C.

  A bias current having a polarity opposite to that of the toner is applied to the collection roller 42. The applied current can be changed. For example, when it is necessary to clean the toner image formed on the intermediate transfer belt 7 at the time of paper jam or the like, the amount of toner to be removed is large. A high current is applied.

  The cleaning blade 43 comes into contact with the collection roller 35 from the counter direction with respect to the rotation direction of the collection roller 42 on the downstream side in the rotation direction of the collection roller 42 with respect to the contact portion C2 between the rotary brush 41 and the collection roller 42. It is supported by. The cleaning blade 43 is formed of a resin such as polyurethane or PET, for example. Let D be the total width of the cleaning blade 43.

  The seal member 44 is supported so as to come into contact with the collection roller 42 from below between the contact portion C <b> 2 between the rotating brush 41 and the collection roller 32 and the cleaning blade 43. By this seal member 44, the inside of the support member 40 is partitioned into a space 40 a on the side where the rotating brush 41 is disposed and a space 40 b on the side where the toner scraped off by the cleaning blade 43 is accommodated. The seal member 44 is formed of, for example, a urethane sheet.

  The screw member 45 is rotatably supported below the cleaning blade 43 on the downstream side in the rotation direction of the collection roller 42 with respect to the seal member 44.

  As shown in FIG. 3, the maximum width A of the toner image forming area 7c of the intermediate transfer belt 7, the full width B of the rotating brush 41, the full width C of the collection roller 42, and the full width D of the cleaning blade 43 are A The relational expression <B <D <C is established.

  In the cleaning device 10 having the above configuration, residual toner and paper dust remaining on the surface of the intermediate transfer belt 7 are trapped between the brush fibers at the contact portion C1 between the intermediate transfer belt 7 and the rotating brush 41. Be collected. The collected residue moves from between the brush fibers to the collecting roller 42 due to a potential difference between the rotating brush 41 and the collecting roller 42 at the contact portion C2 between the rotating brush 41 and the collecting roller 42. The residue transferred to the collection roller 42 is mechanically scraped and dropped by the cleaning blade 43. The scraped residue is discharged out of the apparatus by the recovery screw 45. Further, the seal member 44 prevents the backflow of toner from the space 40b on the cleaning blade 43 side to the space 40a on the rotating brush 41 side.

  In the cleaning device 10, the maximum width A of the toner image forming region 7 c of the intermediate transfer belt 7, the total width B of the rotating brush 41, the total width C of the collection roller 42, and the total width D of the cleaning blade 43 are A <. Since the relational expression of B <D <C is set to hold, toner accumulation at the end of the collection roller 42 can be prevented.

  With reference to FIGS. 4A and 4B, a mechanism for preventing toner accumulation will be described. 4A and 4B are views showing the positional relationship between the intermediate transfer belt, the rotating brush, the collection roller, and the end of the cleaning blade, and FIG. 4A prevents toner collection on the collection roller. FIG. 4B shows the positional relationship in which toner accumulation occurs.

  As shown in FIG. 4A, when the entire width B of the rotating brush 41 is made wider than the maximum width A of the toner image forming area 7c of the intermediate transfer belt 7, the rotating brush 41 is formed at the end of the toner image forming area 7c. The toner scattered when contacted is collected in a portion 41a (a portion indicated by hatching in FIG. 4A) where the rotating brush 41 extends outside the toner image forming region 7c, and the scattered toner is collected. The roller 42 is not reached.

  On the other hand, as shown in FIG. 4B, when the maximum width A of the toner image forming area 7c is made equal to the entire width B of the rotating brush 41, the rotating brush 41 comes into contact with the end of the toner image forming area 7c. As shown by the arrow in FIG. 4B, the toner scattered on the toner particles adheres to the end of the collection roller 42 beyond the rotating brush 41, and as a result, a toner pool is generated at the end of the collection roller 42. .

  Further, by making the full width C of the collection roller 42 wider than the full width B of the rotary brush 41, the toner collected by the rotary brush 41 can be reliably moved to the collection roller 42. Further, the cleaning blade 43 is formed in a region on the recovery roller 42 where the toner is recovered by making the entire width D of the cleaning blade 43 longer than the entire width B of the rotating brush 41 and shorter than the entire width C of the recovery roller 42. Contact in the width direction with a margin. That is, the width of the area where the toner is collected on the collection roller 42 is substantially equal to the entire width B of the rotating brush 41, and the entire width D of the cleaning blade 43 is longer than the entire width B of the rotating brush 41. The cleaning blade 43 contacts the area with a margin in the width direction, and the toner collected by the collection roller 42 can be surely scraped off by the cleaning blade 43.

  Each end of the rotating brush 41 is separated by 2 mm or more from each end of the toner image forming area 7c so that the toner scattered from the end of the toner image forming area 7c is transferred to the collecting roller 42. It can be reliably collected by the rotating brush 41 before reaching.

  Next, the relationship between the maximum width A of the toner image forming region 7 c of the intermediate transfer belt 7, the total width B of the rotating brush 41, the total width C of the collection roller 42, and the total width D of the cleaning blade 43, and the rotating brush 41. The result of an experiment conducted on the influence of the distance between the end of the toner and the end of the toner image forming area 7c on the toner pool will be described.

Table 1 shows the result of visually determining the toner accumulation at the end of the collection roller 42 after performing a predetermined number of printing tests under the same experimental conditions. The case where no toner accumulation was confirmed was indicated as ◯, the case where occurrence of toner accumulation was confirmed as x, and the case where occurrence of a small amount of toner accumulation was confirmed as Δ.

  From the results shown in Table 1, toner accumulation occurs when A <B <D <C and the distance between the end of the rotating brush 41 and the end of the toner image forming area 7c is 2 mm or more. You can see that it is not. In other words, even in the case of Comparative Example 1 where A <B <D <C, the distance between the end of the rotating brush 41 and the end of the toner image forming region 7c is 1.5 mm which is smaller than 2 mm. In this case, a small amount of toner pool is generated, and when the interval is 1 mm as in Comparative Example 2, the toner pool is generated. Therefore, in order to reliably collect the toner scattered from the end portion of the toner image forming region 7c by the rotation of the rotating brush 41 with the rotating brush 41, the end portion of the rotating brush 41 and the end portion of the toner image forming region 7c. It can be seen that the interval needs to be 2 mm or more.

  On the other hand, Comparative Example 3 is a case where the end of the rotating brush 41 and the end of the toner image forming region 7c are at the same position. In this case, as shown in FIG. The toner scattered from the end of the toner image forming area 7c due to the rotation of the toner passes through the rotating brush 41 and adheres to the end of the collecting roller 42, and a toner pool is generated.

  Further, as in Comparative Example 4, even when the interval between the end of the rotating brush 41 and the end of the toner image forming region 7c is 2 mm, the width of the rotating brush 41 and the collection roller 42 is the same, and the cleaning blade 43 has the same width. When the width is larger than the width, the toner collected by the collecting roller 42 from the rotating brush 41 is not scraped by the cleaning blade 43 at both ends of the collecting roller 42, so that the toner remains attached to both ends of the collecting roller 42. End up.

  Further, as in Comparative Example 5, the interval between the end of the rotating brush 41 and the end of the toner image forming region 7c is 1 mm, and the widths of the rotating brush 41, the collection roller 42, and the cleaning blade 43 are the same. In this case, not only the toner reservoir of the recovery roller 42 but also the shaft of the recovery roller 42 is contaminated with toner, and the edge of the cleaning blade 43 is lost. This is presumably because the toner scattered from the end portion of the toner image forming region 7 c due to the rotation of the rotating brush 41 passes through the rotating brush 41 and the collecting roller 42 and adheres to the shaft of the collecting roller 42. Further, by making the widths of the collection roller 42 and the cleaning blade 43 the same, the angle between the outer peripheral surface and the end surface of the collection roller 42 contacts the vicinity of the edge of the cleaning blade 43, and the edge of the cleaning blade 43 is missing. it is conceivable that.

  As described above, in the color printer 1 according to the embodiment of the present invention, the toner scattered at the end of the toner image forming region 7c of the intermediate transfer belt 7 is reliably collected on the rotating brush 41, and the rotating brush 41 Therefore, the toner collected on the collecting roller 42 can be scraped off by the cleaning blade 43 with a margin, so that the toner accumulation on the collecting roller 42 can be prevented.

  In the present embodiment, since the support member 40 of the cleaning device 10 is supported so as to be movable in a direction approaching or separating from the driven roller 8L, the position of the cleaning device 10 is adjusted according to the cleaning performance. be able to. For example, when the rotary brush 41 is used over time and the toner collecting performance is lowered, the support member 40 is moved closer to the driven roller 8L to bring the rotary brush 41 closer to the intermediate transfer belt 7, thereby The toner collecting performance from the transfer belt 7 can be enhanced.

  Also, assuming that the rotation speed of the intermediate transfer belt 7 is v1, the rotation speed of the rotary brush 41 is v2, and the rotation speed of the collection roller 42 is v3, each rotation speed is usually based on the rotation speed v1 of the intermediate transfer belt 7. Is set to v1: v2: v3 = 1: 1.2: -1.2 (minus indicates rotation in the opposite direction). However, for example, when the color printer 1 has a cleaning mode in which the intermediate transfer belt 7 is intensively cleaned, the rotational speeds of the rotating brush 41 and the collection roller 42 are increased so that v1: v2: v3 = 1: By setting the ratio to 1.5: -1.5, the intermediate transfer belt 7 can be effectively cleaned. The rotational speeds v2 and v3 of the rotating brush 41 and the collection roller 42 are preferably increased by about 25% with respect to the rotational speed v1 of the intermediate transfer belt 7.

  Further, in the embodiment of the present invention, the case where the configuration of the present invention is applied to the color printer 1 has been described. However, in another different embodiment, an image forming apparatus other than the color printer 1 such as a copying machine, a facsimile machine, or a multifunction machine. The configuration of the present invention may be applied to.

  Furthermore, since the above description of the embodiment of the present invention describes a preferred embodiment of the image forming apparatus according to the present invention, there may be various technically preferable limitations. The technical scope of the present invention is not limited to these embodiments unless specifically described to limit the present invention. That is, the above-described components in the embodiment of the present invention can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible. The description of the embodiment of the present invention described above does not limit the contents of the invention described in the claims.

1 Color printer (image forming device)
7 Intermediate transfer belt (image carrier)
7c Toner image forming area 10 Cleaning device 41 Rotating brush 42 Recovery roller 43 Cleaning blade

Claims (5)

An image carrier that is rotatably provided and on which a toner image is formed;
A rotating brush that contacts the surface of the image carrier after the toner image is transferred to a transfer paper and collects residues adhering to the surface;
A collection roller for removing the residue collected on the rotating brush;
A cleaning blade that scrapes off the residue collected on the collection roller;
An image forming apparatus comprising:
When the maximum width of the toner image forming region of the image carrier is A, the full width of the rotating brush is B, the full width of the collection roller is C, and the full width of the cleaning blade is D,
A <B <D <C
An image forming apparatus configured to satisfy the relational expression:   The total width B of the rotating brush is 4 mm or more longer than the maximum width A of the toner image forming area, and each end in the width direction of the rotating brush is 2 mm longer than each end in the width direction of the toner image forming area. The image forming apparatus according to claim 1, wherein the image forming apparatus is spaced outward.   The rotating brush, the collection roller, and the cleaning blade are supported by a support member, and the support member is provided so as to be movable in a direction approaching or separating from the image carrier. Item 3. The image forming apparatus according to Item 1 or 2.   The rotating brush and the collection roller rotate in the opposite direction at the same rotational speed, and the rotating brush is configured to come into contact with the rotating direction of the image carrier from the counter direction, and the rotating brush The image forming apparatus according to claim 1, wherein a rotation speed of the recovery roller can be changed to be higher than a rotation speed of the image carrier. 5. The image bearing member according to claim 1, wherein the image carrier is an endless intermediate transfer belt, and includes a plurality of image forming units arranged in a tandem shape along a rotation direction of the intermediate transfer belt. 2. The image forming apparatus according to item 1.

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