JP2005309472A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent toner on a cleaning blade from sticking to an image region of an intermediate transfer belt due to the impact of the cleaning blade being abutted to an intermediate transfer belt, in an image forming apparatus carrying out primary transfer of a toner image formed on a photoreceptor to the surface of the intermediate transfer belt, carrying out secondary transfer of the toner image to transfer paper as well as removing transfer residual toner stuck to the intermediate transfer belt surface after secondary transfer. <P>SOLUTION: To use a cleaning blade which is directed in the direction of trailing with respect to the direction of movement of the intermediate transfer belt 5, as the cleaning blade 17 abutted to the surface of the intermediate transfer belt 5 and removing the transfer residual toner on the surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides an image carrier that sequentially forms toner images of different colors on the surface while being rotationally driven, an intermediate transfer member on which the toner images are sequentially superimposed and primarily transferred while being rotationally driven, and the intermediate transfer The residual toner adhering to the surface of the intermediate transfer body after secondary transfer of the superposed toner images that have been primarily transferred to the body surface to the recording medium is removed from the surface of the intermediate transfer body to clean the surface of the intermediate transfer body A cleaning device provided with a cleaning member that is separated from the surface of the intermediate transfer member when the toner image on the surface of the intermediate transfer member before being secondarily transferred to the recording medium passes through the cleaning member. An image forming apparatus supported so as to be in contact with and away from the surface of the intermediate transfer body so as to be in contact with the surface of the intermediate transfer body when removing the transfer residual toner from the surface of the intermediate transfer body About.

  An image forming apparatus of the above type configured as a copying machine, a printer, a facsimile, or a multifunction machine having at least two of these functions is well known. The surface of the intermediate transfer member after the toner image is secondarily transferred is cleaned by a cleaning member, and then the next toner image is sequentially primary transferred onto the surface of the intermediate transfer member. Conventionally, a cleaning blade that contacts the surface of the intermediate transfer member in the counter direction has been used as such a cleaning member. It is considered that using a counter-facing cleaning blade that is in contact with the moving direction of the surface of the intermediate transfer member and the tip edge of which is in pressure contact can effectively remove residual toner on the surface of the intermediate transfer member. This is because.

  However, according to a study by the present inventor, when a counter type cleaning blade is used, when the cleaning blade comes into contact with the surface of the intermediate transfer member, the impact is applied to the surface of the cleaning blade facing the surface of the intermediate transfer member. It has been found that the toner adhering to the surface is scattered and adheres to the surface of the intermediate transfer member, which may cause scumming on the toner image formed next on the surface of the intermediate transfer member. The reason for this is that in this type of image forming apparatus, the cleaning blade comes into contact with the surface of the moving intermediate transfer member, so that the counter type cleaning blade hits the surface of the intermediate transfer member. This is because the toner adhering to the cleaning blade surface adheres over a wide range of the surface of the intermediate transfer member. As described above, when the cleaning blade that contacts the surface of the intermediate transfer member in the counter direction is used, although the cleaning efficiency of the blade itself is improved, the scattered toner adheres to the surface of the intermediate transfer member and is formed next. The image quality of the image is degraded.

  The present invention has been made on the basis of the above-described novel recognition, and an object of the present invention is to provide an image forming apparatus of the type described at the beginning, which eliminates the above-mentioned conventional drawbacks.

  In order to achieve the above object, according to the present invention, in the image forming apparatus of the type described at the beginning, a cleaning blade that contacts the surface of the intermediate transfer member in the trailing direction is used as the cleaning member. An apparatus is proposed (claim 1).

  At that time, in addition to the cleaning blade, the cleaning device receives a transfer residual toner removed from the intermediate transfer member surface by the cleaning blade, and a position where the cleaning blade contacts the intermediate transfer member surface, A seal member that contacts the intermediate transfer member surface portion upstream of the intermediate transfer member in the moving direction and prevents the toner in the cleaning case from scattering, and the sealing member and the cleaning blade have their base ends The cleaning case is intermediate to the contact portion of the seal member with respect to the intermediate transfer member surface so that the side is fixed to the cleaning case and the free end side of the cleaning blade and the seal member is in contact with and away from the intermediate transfer member surface. It is supported so as to be swingable at the upstream side of the transfer surface in the moving direction, When the cleaning blade and the seal member contact the surface of the intermediate transfer body, the seal member first contacts, then the cleaning blade contacts, and when the cleaning blade and the seal member separate from the surface of the intermediate transfer body, the cleaning is performed first. It is advantageous to set the assembly position of the cleaning blade and the seal member with respect to the cleaning case so that the blade is separated and then the seal member is separated (Claim 2).

  The image forming apparatus according to claim 1 or 2, wherein the driving member for bringing the cleaning blade into and out of contact with the surface of the intermediate transfer member is preferably a cam that is rotationally driven by a predetermined angle range. (Claim 3).

  The image forming apparatus according to claim 2, wherein the driving member that contacts and separates the cleaning blade and the seal member from the surface of the intermediate transfer member is rotationally driven by a predetermined angle range while being pressed against the cleaning case. It is advantageous if it comprises a cam (claim 4).

  According to the image forming apparatus of the first aspect, since the trailing cleaning blade is used as the cleaning member for removing the transfer residual toner adhering to the surface of the intermediate transfer member, the toner image formed on the surface of the intermediate transfer member. Can reduce the background stain and improve the image quality.

  According to the image forming apparatus of claim 2, when the cleaning blade and the seal member are separated from the surface of the intermediate transfer body, the cleaning member is first separated, and then the seal member is separated, so that the cleaning blade is separated from the surface of the intermediate transfer body. Even if the toner falls, it can be prevented that the toner is scattered outside the cleaning case. In addition, since the cleaning blade and the seal member are integrally assembled to the cleaning case, and the cleaning case can be swung to bring the cleaning blade and the seal member into contact with and away from the surface of the intermediate transfer member, the configuration of the cleaning device Can be simplified and its cost can be reduced.

  According to the image forming apparatus of the third aspect, the cleaning blade is swung by the cam and the cleaning blade is brought into contact with and separated from the surface of the intermediate transfer member. Therefore, it is possible to prevent image quality degradation.

  According to the image forming apparatus of the fourth aspect, the cleaning blade and the seal member are swung by the cam so that the cleaning blade and the seal member are brought into contact with and separated from the surface of the intermediate transfer member. Therefore, it is possible to prevent image quality deterioration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, and the above-mentioned conventional defects will be clarified more specifically with reference to the drawings.

  FIG. 1 is a schematic sectional view showing an example of an image forming apparatus according to the present invention. The image forming apparatus shown here is a drum-like member that is rotatably supported by a machine frame of an image forming apparatus main body (not shown). A photoconductor 1 is provided, and the photoconductor 1 constitutes an example of an image carrier. During the image forming operation, the photoreceptor 1 is rotationally driven in the counterclockwise direction (arrow H direction) in FIG. 1, and at this time, the surface thereof is uniformly charged by the charging device 2. This charged surface is exposed by document image light sent in a direction indicated by an arrow 3 through a document reading system and a writing system (not shown), whereby a first electrostatic latent image is formed on the surface of the photosensitive member. It is formed. This first electrostatic latent image is formed into a black toner image by the powdery black toner of the black developing device 4BK of the developing device 4.

  On the other hand, an endless intermediate transfer belt 5, which is an example of an intermediate transfer body, is disposed facing the surface of the photoreceptor 1, and the intermediate transfer belt 5 includes a pair of bias rollers 6, a drive roller 6 </ b> A, and a driven roller. The roller 6B is wound around and rotated in the direction of arrow I. The intermediate transfer belt portion between the pair of bias rollers 6 abuts along the peripheral surface of the photoreceptor 1 so that the photoreceptor 1 and the intermediate transfer belt 5 move at the same speed in the same direction. Then, the intermediate transfer belt 5 is driven.

  A voltage having a reverse polarity to the toner of the toner image formed on the photoconductor is applied to the pair of bias rollers 6, and is formed on the surface of the photoconductor on the intermediate transfer belt portion in contact with the peripheral surface of the photoconductor 1. When the above-described black toner image arrives, the black toner image on the photosensitive member is primarily transferred onto the surface of the intermediate transfer belt 5 by the current supplied to the bias roller 6. As described above, the bias roller 6 constitutes a transfer unit that primarily transfers the toner image formed on the surface of the image carrier to the intermediate transfer member. The transfer residual toner adhering to the surface of the photoconductor after the toner image is transferred is removed from the surface of the photoconductor by the cleaning member 8A of the photoconductor cleaning device 8 after being subjected to a charge eliminating action by the charge eliminator 7.

  After the cleaning, the surface of the photosensitive member is again subjected to the discharging operation by the discharging lamp 9, and then uniformly charged by the charging device 2 again, and then exposed again by the original image light. An image is formed. This electrostatic latent image is visualized as a cyan toner image made of powdered cyan toner by the cyan developing device 4C of the developing device 4, and this toner image is rotated in the same manner as described above. Primary transfer is performed on the surface of the intermediate transfer belt 5 so as to overlap the black toner image previously transferred. Transfer residual toner adhering to the surface of the photoconductor after the toner image is transferred is also subjected to a static elimination action by the static eliminator 7 and then removed from the photoconductor surface by the photoconductor cleaning device 8.

  Exactly in the same manner, third and fourth electrostatic latent images are sequentially formed on the photosensitive member, and these electrostatic latent images are formed by the powder toners of the magenta developing unit 4M and the yellow developing unit 4Y of the developing device 4. The toner images are visualized as magenta toner images and yellow toner images, respectively, and these toner images are also primarily transferred onto the surface of the intermediate transfer belt 5 sequentially from the previously transferred toner images. The residual transfer toner that adheres to the surface of the photoreceptor after the primary transfer of each toner image is also removed by the cleaning device 8. In this way, four color toner images are formed on the surface of the intermediate transfer belt 5 in a superimposed state.

  On the other hand, a transfer sheet 11 as an example of a recording medium fed from a paper feeding device (not shown) is sent at a predetermined timing between the intermediate transfer belt 5 and a transfer roller 12 as an example of a secondary transfer unit. It is. When the leading edge of the transfer paper 11 reaches the transfer roller 12, the transfer roller 12 is raised, and the transfer paper 11 is conveyed while being sandwiched between the transfer roller 12 and the intermediate transfer belt 5. At this time, the transfer roller 12 is transferred. The superposed full color toner image on the surface of the intermediate transfer belt 5 is secondarily transferred onto the transfer paper in a batch by the current supplied to. The transfer roller 12 is rotationally driven in the direction indicated by the arrow in FIG.

  Subsequently, the transfer paper 11 is separated from the intermediate transfer belt 5 and is transported to the fixing device 14 by the transport belt 13, where the toner image transferred onto the transfer paper 11 by the action of heat and pressure is fixed on the transfer paper. The Next, the transfer paper is discharged to the paper discharge unit 15 as the final copy paper.

  The transfer residual toner remaining on the surface of the intermediate transfer belt without being transferred to the transfer paper 11 in the secondary transfer step is removed by a cleaning member configured as a cleaning blade 17 of the cleaning device 10, and the surface of the intermediate transfer belt is cleaned. The The cleaning blade 17 is separated from the surface of the intermediate transfer belt when the toner image on the surface of the intermediate transfer belt 5 before the secondary transfer passes through the cleaning blade 17. The cleaning blade 17 contacts the surface of the intermediate transfer belt when it removes transfer residual toner on the surface of the intermediate transfer belt. The next toner image is sequentially primary transferred onto the surface of the intermediate transfer belt thus cleaned, and the above-described operation is repeated.

  As described above, the image forming apparatus of the present example includes the image carrier configured as the photoreceptor 1 on which the toner images of different colors are sequentially formed on the surface while being rotated, and the toner images described above while being rotated. After the intermediate transfer body composed of the intermediate transfer belt 5 on which the toner images are sequentially superimposed and primary transferred, and the superimposed toner images primarily transferred onto the surface of the intermediate transfer body are collectively transferred to the recording medium composed of the transfer paper 11 after the secondary transfer. And a cleaning device 10 including a cleaning member that removes transfer residual toner adhering to the surface of the intermediate transfer member from the surface of the intermediate transfer member and cleans the surface of the intermediate transfer member.

  The cleaning member is configured as a cleaning blade 17, and the cleaning member is separated from the surface of the intermediate transfer member when the toner image on the surface of the intermediate transfer member before the secondary transfer to the recording medium passes through the cleaning member, and the intermediate transfer member When the transfer residual toner is removed from the surface of the body, the toner is supported so as to be in contact with and away from the surface of the intermediate transfer body so as to be in contact with the surface of the intermediate transfer body.

  Here, as described above, the cleaning member is configured as the cleaning blade 17 made of an elastic body such as rubber, and the cleaning blade 17 is formed as a substantially rectangular parallelepiped plate-like body, and the base end side thereof is made of metal or the like. The holder 18 is fixed to the free end of the rigid body 18, and the base end of the holder 18 is fixed to the inner wall surface of the cleaning case 19. The proximal end side of the cleaning blade 17 can be directly fixed to the cleaning case 19.

  When the cleaning blade 17 comes into contact with the surface of the intermediate transfer belt 5, one of the leading edge portions comes into pressure contact with the surface of the intermediate transfer belt 5, and scrapes off and removes the transfer residual toner adhering to the surface. The removed transfer residual toner is received by the cleaning case 19, and is discharged to the outside of the cleaning case 19 by a toner discharge member 20 that is disposed on the bottom of the cleaning case 19 and is driven to rotate, such as a coil or a screw. It is stored in a waste toner bottle (not shown).

  In addition, a base end side of a sheet-like seal member 21 made of, for example, a resin such as urethane is fixed to a portion of the cleaning case 19 facing the intermediate transfer belt 5, and the cleaning blade 17 comes into contact with the surface of the intermediate transfer belt 5. In this case, the free end side of the seal member 21 contacts the surface of the intermediate transfer belt as shown in FIG. The seal member 21 has elasticity, and the seal member 21 has an intermediate transfer belt surface on the upstream side in the movement direction of the intermediate transfer belt surface from the position where the tip edge portion of the cleaning blade 17 contacts the surface of the intermediate transfer belt 5. Abutting on the portion covers the space between the cleaning case 19 and the intermediate transfer belt 5 and prevents the transfer residual toner scraped off by the cleaning blade 17 from being scattered outside the cleaning case 19.

  The cleaning case 19 has an image formed at a position upstream of the contact portion of the cleaning blade 17 and the seal member 21 with respect to the surface of the intermediate transfer belt 5 in the moving direction on the surface of the intermediate transfer belt, in the illustrated example, at the toner discharge member 20. It is supported to be swingable with respect to the forming apparatus main body. That is, in addition to the above-described elements, the cleaning device 10 has a frame 22 positioned with respect to the image forming apparatus main body as shown in FIG. Each shaft end portion of the discharge member 20 is rotatably supported by the frame 22, whereby the cleaning case 19 is supported by the image forming apparatus main body through the frame 22 so as to be swingable.

  On the other hand, a motor 25 is fixedly disposed in the image forming apparatus main body as shown in FIG. 1, and a pulley 25A is fixed to the output shaft thereof. Further, as shown in FIG. 2, a half-rotation clutch 23 is supported on the side plate 16 (not shown in FIG. 1) constituting the machine frame of the main body of the image forming apparatus and fixed to the input side thereof. A timing belt 24 is wound around the pulley 23A and the pulley 25A. Further, one joint member 27A of the joint 27 is fixed to the output side of the half-rotation clutch 23, and the other joint member 27B is an end on the back side of the rotary shaft 26 that is rotatably supported by the frame 22 of the cleaning device 10. It is fixed to the part. Both joint members 27A and 27B are engaged with each other and transmit the rotation of one joint member 27A to the other joint member 27B. Both joint members 27A and 27B can be separated from each other in the axial direction.

  The rotating shaft 26 extends in parallel to the cleaning case 19, and an appropriate number of cams 28 are fixed to the rotating shaft 26, and each of the pressure members including tension springs 29 is attached to the frame 22 and the cleaning case 19. The end portions are respectively locked, whereby the cleaning case 19 is pressed against the cam surface of the cam 28.

  As shown in FIG. 1, when the cleaning blade 17 and the seal member 21 are in contact with the surface of the intermediate transfer belt 5, the large diameter portion 28 </ b> A of the cam 28 is in pressure contact with the cleaning case 19. On the other hand, when the cleaning blade 17 and the seal member 21 are separated from the surface of the intermediate transfer belt 5, the rotation of the drive motor 25 is caused by the half-rotation clutch 23 via the pulley 25A, the timing belt 24, and the other pulley 23A. As a result, the cam 28 rotates 180 ° together with the joint 27 and the rotary shaft 26. As a result, as shown in FIG. 3, the small diameter portion 28 </ b> B of the cam 28 comes into pressure contact with the cleaning case 19, and at this time, the cleaning blade 17 and the seal member 21 are separated from the surface of the intermediate transfer belt 5.

  Again, the rotation of the motor 25 is transmitted to the cam 28 via the half-rotation clutch 23 and rotated 180 ° so that the large-diameter portion 28A of the cam 28 comes into pressure contact with the cleaning case 19, and at this time, the cleaning blade 17 and The free end side of the seal member 21 is in pressure contact with the surface of the intermediate transfer belt 5. Instead of transmitting the rotation of the motor to the cam 28 via the timing belt 24, the rotation can be transmitted via a gear.

  As described above, the cleaning blade 17 contacts the intermediate transfer belt 5 together with the seal member 21, cleans the image area of the intermediate transfer belt that is next primarily transferred onto the intermediate transfer belt 5, and then the intermediate transfer belt. It stands by in a state where it is separated from the surface and does not disturb the superimposed toner image to be transferred next onto the intermediate transfer belt 5.

  One joint member 27A of the joint 27 is disposed on the image forming apparatus main body side, the other joint member 27B is provided on the rotating shaft 26 side of the cleaning device 10, and both the joint members 27A and 27B are detachably engaged with each other. doing. Accordingly, the frame 22, the rotating shaft 26 rotatably supported by the frame 22, the cleaning case 19 supported by the frame 22 so as to be swingable, the spring 29, the cam 28, and the cleaning integrally assembled with the cleaning case 19. The cleaning device 10 including the blade 17 and the seal member 21 can be pulled out in front of the image forming apparatus main body, that is, in the direction indicated by the arrow J in FIG. At this time, the frame 22 is guided by a guide (not shown) and slides forward. When the cleaning device 10 is again pushed into the position shown in FIGS. 1 and 2, the joint members 27A and 27B are engaged with each other, and the frame 22 is correctly positioned with respect to the image forming apparatus main body and held stationary. Is done.

  Here, as understood from FIG. 1, the cleaning blade 17 scrapes and removes transfer residual toner on the surface of the intermediate transfer belt 5 while contacting the surface of the intermediate transfer belt 5 in the trailing direction. As the cleaning member, a cleaning blade 17 that contacts the surface of the intermediate transfer member in the trailing direction is used.

  As described above, the cleaning blade 17 of this example that contacts the surface of the intermediate transfer belt 5 in the trailing direction is composed of a thin rectangular plate-like body made of an elastic body, as described above. When pressed against the surface of the belt 5, one end face 30 in the thickness direction faces the surface of the intermediate transfer belt 5 as schematically shown in an enlarged manner in FIG. 4. At this time, of the two leading edge portions 31 and 32 that define the end face 30 and extend substantially parallel to each other, the upstream leading edge portion 31 is formed of the intermediate transfer belt 5 with respect to the moving direction of the intermediate transfer belt surface. Press contact with the surface of the intermediate transfer member. In this way, the cleaning blade 17 scrapes and removes the transfer residual toner adhering to the surface of the intermediate transfer belt 5.

  On the other hand, as shown in FIG. 5, the counter-oriented cleaning blade 17A has two leading edge portions 31A and 32A that define the end face 30A facing the intermediate transfer belt 5 in the same state as described above. Among them, with respect to the movement direction of the surface of the intermediate transfer belt 5, the downstream edge portion 32 </ b> A comes into pressure contact with the surface of the intermediate transfer belt 5 and scrapes off and removes the transfer residual toner adhering to the surface.

  When the trailing cleaning blade 17 and the counter cleaning blade 17A are compared, the latter counter cleaning blade 17A has a higher ability to scrape off the toner from the intermediate transfer belt 5. Therefore, in this type of conventional image forming apparatus, the counter type cleaning blade 17A is exclusively used.

  However, as described above, the cleaning blade contacts or separates from the surface of the intermediate transfer belt 5 while it is moving. Therefore, when the counter type cleaning blade 17A is used, the cleaning blade is cleaned. The toner may adhere to the image area on the surface of the intermediate transfer belt after being cleaned by the blade. In this respect, in this type of image forming apparatus, a trailing-type cleaning member is used as a cleaning member for cleaning the intermediate transfer belt. It is advantageous to use a cleaning blade.

  Here, in order to clarify the advantages of using the trailing cleaning blade 17, the configuration of the cleaning device using the counter type cleaning blade 17A and its drawbacks are shown in FIGS. This will be described in comparison with the blade 17.

  As described above, in the cleaning device 10 shown in FIG. 1, the proximal end side of the cleaning blade 17 is fixed to the cleaning case 19 via the holder 18, and the cleaning case 19 is located at the site of the toner discharge member 20. The image forming apparatus main body is swingably supported through the frame 22. The center of the swing is on the upstream side in the movement direction of the surface of the intermediate transfer belt 5 from the portion where the cleaning blade 17 and the seal member 21 are in contact with the intermediate transfer belt 5. Accordingly, the cleaning blade 17 can also swing around a portion (a portion of the toner discharge member 20) on the upstream side in the movement direction of the surface of the intermediate transfer belt with respect to the contact portion when the cleaning blade 17 contacts the surface of the intermediate transfer belt. It is supported by. Therefore, the cleaning blade 17 rotates in the direction of the arrow A as shown in FIGS. 6A and 6B when the cleaning blade 17 comes into contact with the intermediate transfer belt 5 from the separated state.

  Similarly to the above, the counter type cleaning blade 17A is fixed to the cleaning case 19A of the cleaning device 10A via the holder 18A as described above, and the cleaning case 19A and the cleaning blade 17A are fixed. Is supported to be swingable around the toner discharge member 20A on the upstream side with respect to the moving direction of the intermediate transfer belt 5 with respect to the moving direction of the intermediate transfer belt 5 with respect to the contact portion when the blade 17A contacts the surface of the intermediate transfer belt 5. To do.

  In this case, when the cleaning blade 17A rotates in a direction to contact the intermediate transfer belt 5 and contacts the surface of the intermediate transfer belt in detail, first, the tip edge portion 32A of the cleaning blade 17A is shown in FIG. As shown by the solid line, the surface abuts against the surface of the intermediate transfer belt, and then the leading edge portion 32A comes into strong pressure contact with the surface of the intermediate transfer belt, so that the cleaning blade 17A is slightly bent, and finally takes the posture shown by the chain line in FIG. . At this time, an angle formed between the tangent line T1 drawn to the contact portion between the cleaning blade 17A and the intermediate transfer belt 5 and the cleaning blade 17A in the final posture is θ1, and the cleaning blade 17A in the solid line posture is taken. And θ2> θ1, where θ2 is an angle formed by tangent line T1.

  Here, in order for the counter type cleaning blade 17A to efficiently remove the transfer residual toner on the intermediate transfer belt, the angle θ1 needs to be set to a large angle, but the angle θ2 is the angle θ1. Therefore, the angle θ2 when the cleaning blade 17A starts to contact the surface of the intermediate transfer belt is a larger angle. At this time, the surface of the intermediate transfer belt 5 has moved in a direction facing the cleaning blade 17A. Therefore, when the angle θ2 is large, the tip of the elastic cleaning blade 17A is elastically deformed into the state of being caught in the intermediate transfer belt 5 as shown in FIG. There is a fear. Such deformation is generally referred to as cleaning blade reversal. If such reversal occurs, transfer residual toner on the surface of the intermediate transfer belt cannot be efficiently removed by the cleaning blade 17A.

  As described above, the counter type cleaning blade 17A is rotated around the downstream side of the intermediate transfer belt moving direction from the contact portion when the counter type cleaning blade 17A contacts the intermediate transfer belt 5, and the cleaning blade 17A is rotated. If the cleaning blade 17A is brought into contact with the intermediate transfer belt surface, there is a possibility that the tip portion of the cleaning blade 17A is reversed. The cleaning blade 17A cannot be supported as described above.

  Therefore, when the counter type cleaning blade 17A is used, for example, as shown in FIG. 11, the base of the holder 18A to which the base end side of the cleaning blade 17A is fixed is pivotally supported on the cleaning case 19A via the pin 33A. At the same time, the pin 33A, which is the rotation center of the cleaning blade 17A, is disposed downstream of the contact portion of the cleaning blade 17A with respect to the surface of the intermediate transfer belt in the moving direction of the surface of the intermediate transfer belt. It is necessary to make contact with the surface of the belt 5. The center of oscillation of the cleaning blade 17A must be located downstream of the contact portion between the cleaning blade 17A and the intermediate transfer belt 5 in the intermediate transfer belt moving direction.

  In this way, as indicated by the solid line in FIG. 12, the angle θ2 when the leading edge of the cleaning blade 17A starts to contact the surface of the intermediate transfer belt is the same as indicated by the chain line. Since the angle 17A becomes smaller than the angle θ1 when the final posture is taken, the cleaning blade 17A can be brought into contact with the surface of the intermediate transfer belt 5 at a small angle θ2, thereby the cleaning blade 17A is shown in FIG. Can be reversed.

  However, if the counter type cleaning blade 17A is pivotally supported as described above, the following disadvantages are inevitable.

  FIG. 7 shows a state where the swing center of the cleaning blade 17A is disposed downstream of the contact portion of the cleaning blade 17A with the intermediate transfer belt 5 in the intermediate transfer belt moving direction as shown in FIG. It is explanatory drawing which shows a motion of the cleaning blade 17A. FIG. 7A shows a state where the cleaning blade 17 </ b> A is separated from the surface of the intermediate transfer belt 5. At this time, the toner T based on use over time adheres to the surface 34A of the cleaning blade 17A facing the intermediate transfer belt 5. In this state, when the leading end Y of the image region X after the superimposed toner image on the surface of the intermediate transfer belt 5 is transferred to the transfer paper approaches the cleaning blade 17A, as shown in FIG. It is assumed that the cleaning blade 17A is rotated in the direction of arrow B, and the leading edge portion is brought into pressure contact with the surface of the intermediate transfer belt 5.

  At this time, since the oscillation center of the cleaning blade 17A is set as described above, the powder toner adhering to the surface 34A when the leading edge portion of the cleaning blade 17A collides with the surface of the intermediate transfer belt. T soars upward. In addition, since the area SA when the contact surface 34A is projected onto the surface of the intermediate transfer belt 5 becomes large, the powder toner T away from the surface 34A of the cleaning blade 17A moves in the direction of movement of the surface of the intermediate transfer belt. Soars over a large range.

  The toner swollen in this way falls to the surface of the intermediate transfer belt 5 as shown in FIG. 7C. At this time, the leading end Y of the image region X has already passed the leading edge portion of the cleaning blade 17A. Yes. The toner T that has left the surface 34A soars upward and over a wide range with respect to the surface of the intermediate transfer belt 5, so that the toner adheres to the surface of the image region X. Accordingly, when the next toner image is primarily transferred to the image region X, the toner image adhering to the image region X causes scumming on the toner image.

  On the other hand, in the image forming apparatus of this example shown in FIGS. 1 to 3, the trailing type cleaning blade 17 is used, and as described above, the cleaning blade 17 swings. The center is located on the upstream side in the movement direction of the surface of the intermediate transfer belt with respect to the contact portion of the cleaning blade 17 with respect to the intermediate transfer belt 5. For this reason, when the leading edge portion of the cleaning blade 17 comes into contact with the surface of the intermediate transfer belt 5, there is no possibility that the leading edge is caught in the surface of the intermediate transfer belt and reversed.

  FIGS. 6A and 6B show a state in which the cleaning blade 17 abuts against the surface of the intermediate transfer belt. As can be seen from FIG. When the leading edge portion comes into contact with the surface of the intermediate transfer belt, the cleaning blade 17 is reversed because the cleaning blade 17 only receives an external force in a direction that inherently elastically bends and deforms from the surface of the intermediate transfer belt. Is not possible. Therefore, the swing center of the trailing cleaning blade 17, that is, the toner discharge member 20, is disposed without any hindrance on the upstream side of the intermediate transfer belt surface movement direction with respect to the contact portion of the leading edge portion with respect to the intermediate transfer belt surface. It can be done.

  FIG. 6A shows a state where the cleaning blade 17 is separated from the surface of the intermediate transfer belt. At this time, the powder toner scattered on the one surface 34 during the previous cleaning operation. T is attached. When the front end Y of the image area X on which the toner image on the surface of the intermediate transfer belt 5 has been transferred approaches the cleaning blade 17, the cleaning blade 17 moves to the swing center (toner discharge member 20) shown in FIG. As shown in FIG. 6 (b), it is brought into contact with and brought into contact with the surface of the intermediate transfer belt, the tip edge of which moves in the direction of arrow A.

  At this time, since the position of the swing center of the cleaning blade 17 is set as described above, the cleaning blade 17 contacts the surface of the intermediate transfer belt while maintaining a substantially horizontal posture. For this reason, the toner T adhering to the surface 34 of the cleaning blade 17 jumps out substantially in the horizontal direction and falls and adheres to the surface of the intermediate transfer belt in a short time. In addition, since the area S when the surface 34 of the cleaning blade 17 is projected onto the surface of the intermediate transfer belt 5 is small and becomes almost zero in the example of FIG. 6B, the toner moves in the moving direction of the surface of the intermediate transfer belt. It does not adhere over a large area. In this way, as shown in FIG. 6C, the toner T separated from the surface 34 adheres to the non-image area on the downstream side of the image area X on the surface of the intermediate transfer belt. For this reason, when the next toner image is primarily transferred to the image area X, it is possible to prevent the occurrence of background contamination.

  In the image forming apparatus shown in FIGS. 1 to 3, the cleaning case 19 rotates around the toner discharge member 20, and the free end side of the cleaning blade 17 and the seal member 21 is the surface of the intermediate transfer belt 5. The assembly position of the cleaning blade 17 and the seal member 21 with respect to the cleaning case 19 is set so that the seal member 21 first contacts and then the cleaning blade 17 contacts. With this configuration, when the cleaning blade 17 and the free end side of the seal member 21 are separated from the surface of the intermediate transfer belt 5 as the cleaning case 19 rotates, the cleaning blade 17 is first separated, and then the seal member 21. Are separated.

  When the leading end side of the cleaning blade 17 moves away from the surface of the intermediate transfer belt 5, the toner collected at the leading edge portion of the intermediate transfer belt 5 falls downward due to the impact. As described above, the cleaning blade 17 is in the middle. Since the free end side of the seal member 21 is still in contact with the surface of the intermediate transfer belt when it is separated from the transfer belt surface, the toner dropped from the leading edge portion of the cleaning blade 17 can be received by the seal member 21. Accordingly, it is possible to prevent a problem that the toner is scattered outside the cleaning case 19 and the inside of the image forming apparatus is stained with the toner.

  When the trailing type cleaning blade 17 is used, the base end side of the cleaning blade 17 and the seal member 21 is fixed to the cleaning case 19, and these are assembled together and the cleaning blade 17 for the surface of the intermediate transfer belt 5. The above-described operation can be obtained by a simple configuration in which the cleaning case 19 is swingably supported on the upstream side in the movement direction of the surface of the intermediate transfer belt with respect to the contact portion of the seal member 21.

  However, as shown in FIG. 11, a counter-type cleaning blade 17A is used, and the center of swing is downstream of the contact portion of the cleaning blade 17A with the surface of the intermediate transfer belt with respect to the movement direction of the surface of the intermediate transfer belt. When arranged, it is difficult to configure such that the cleaning blade 17A is first separated from the surface of the intermediate transfer belt and then the seal member 21A is separated from the surface of the intermediate transfer belt.

  The cleaning blade 17A is fixed integrally with the cleaning case 19A via the holder 18A and the pin 33A shown in FIG. 11, and the sealing member 21A is also fixed integrally with the cleaning case 19A at the base end side, and the cleaning member When the case 19A is swingably supported around the pin 33A and the cleaning case 19A is swung by the driving device so that the cleaning blade 17A and the seal member 21A are brought into contact with and separated from the surface of the intermediate transfer belt, When separating from the surface of the intermediate transfer belt, it is extremely difficult to configure such that the cleaning belt 17A is first separated from the intermediate transfer belt 5 and then the seal member 21A is separated.

  Therefore, the cleaning case 19A shown in FIG. 11 is supported immovably with respect to the main body of the image forming apparatus, and the proximal end side of the cleaning blade 17A and the seal member 21A is swung to the cleaning case 19A via the pins 33A and 36A. Although it is necessary to pivot freely and rotate each by a separate driving device, the cleaning blade 17A must first be separated from the surface of the intermediate transfer belt and then the seal member 21 must be separated. Such a configuration is unavoidable for the disadvantage that its cost increases.

  In the image forming apparatus of this example, in addition to the cleaning blade 17, the cleaning device 10 receives a transfer residual toner removed from the surface of the intermediate transfer member formed by the intermediate transfer belt 5 by the cleaning blade 17, and A sealing member that prevents the toner in the cleaning case 19 from scattering by contacting the surface of the intermediate transfer body upstream of the position where the cleaning blade 17 contacts the surface of the intermediate transfer body in the moving direction. 21, the sealing member 21 and the cleaning blade 17 are fixed to the cleaning case 19 at the base end side, and the free end side of the cleaning blade 17 and the sealing member 21 is in contact with and away from the surface of the intermediate transfer member. In addition, the cleaning case 19 is attached to the surface of the intermediate transfer member. When the cleaning blade 17 and the seal member 21 come into contact with the surface of the intermediate transfer body, they are supported so as to be swingable at a position upstream of the contact portion of the member 21 in the movement direction on the surface of the intermediate transfer body. And then the cleaning blade 17 abuts, and when the cleaning blade 17 and the seal member 21 are separated from the surface of the intermediate transfer member, the cleaning blade 17 is first separated and then the seal member 21 is separated. The assembly position of the cleaning blade 17 and the seal member 21 with respect to the case 19 is set. With this, when the cleaning blade 17 moves away from the surface of the intermediate transfer member, the toner dropped from the cleaning blade 17 is cleaned by a simple configuration. To splash outside the case 19 It is possible to stop.

  By the way, in this type of conventional image forming apparatus, a link operated by a solenoid is used as a driving member for bringing the cleaning blade and the seal member into contact with and separating from the surface of the intermediate transfer belt. However, this structure not only complicates the structure, but also causes a large impact when the cleaning blade and the seal member come in contact with and separates from the surface of the intermediate transfer belt. Acts to cause a load fluctuation of the intermediate transfer belt. For this reason, the color shift of the toner image formed on the intermediate transfer belt and the scattering of the toner from the toner image may occur, which may deteriorate the image quality of the final image.

  On the other hand, in the image forming apparatus shown in FIGS. 1 to 3, the cleaning case 19 is pressed against the cam 28 by a pressurizing member made of a tension spring 29, and the cam 28 is driven to rotate by a predetermined angle for cleaning. Since the case 19 is swung and thereby the cleaning blade 17 and the seal member 21 are brought into contact with and separated from the surface of the intermediate transfer belt 5, the impact at the time of contact and separation can be effectively suppressed.

  The driving member for bringing the cleaning blade 17 into and out of contact with the surface of the intermediate transfer member is constituted by a cam 28 that is rotationally driven by a predetermined angle range, and the cleaning blade 17 and the seal member 21 are in contact with the surface of the intermediate transfer member. The image quality of the final image can be improved by configuring the drive member to be separated from a cam that is rotationally driven by a predetermined angle range while being pressed against the cleaning case.

  Although specific embodiments of the present invention have been described above, it is obvious that the present invention can be widely applied to other types of image forming apparatuses. For example, the present invention can be applied to an image forming apparatus using an endless belt-shaped image carrier or a drum-shaped intermediate transfer body without any trouble.

1 is a schematic cross-sectional view schematically showing an example of an image forming apparatus according to the present invention. It is a top view of the one part element shown in FIG. FIG. 6 is a cross-sectional view illustrating a state where a cleaning blade and a seal member are separated from the surface of an intermediate transfer belt by rotation of a cam. It is a figure explaining the basic composition of the cleaning blade of a trailing method. It is a figure explaining the basic composition of the conventional counter type cleaning blade. FIG. 2 is a diagram for explaining an operation when the cleaning blade shown in FIG. 1 abuts against the surface of an intermediate transfer belt. FIG. 6 is a diagram illustrating an operation when a counter type cleaning blade comes into contact with the surface of an intermediate transfer belt. It is sectional drawing which shows an example which supports the conventional cleaning blade of a counter system so that rocking | fluctuation is possible. It is a figure explaining the malfunction when the structure shown in FIG. 8 is employ | adopted. It is explanatory drawing which shows a state when the conventional counter type cleaning blade is reversed. It is sectional drawing which shows the other example which supports the conventional counter type cleaning blade. FIG. 12 is an explanatory diagram showing a state when the counter type cleaning blade shown in FIG. 11 contacts the surface of the intermediate transfer belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cleaning device 17 Cleaning blade 19 Cleaning case 21 Seal member 28 Cam

Claims (4)

An image carrier on which toner images of different colors are sequentially formed on the surface while being rotated, an intermediate transfer member on which the toner images are sequentially superimposed and primarily transferred while being rotated, and a primary surface on the surface of the intermediate transfer member A cleaning member that removes transfer residual toner adhering to the surface of the intermediate transfer body after the transferred toner images are secondarily transferred to the recording medium and cleaning the surface of the intermediate transfer body; A cleaning device provided, and the cleaning member is separated from the surface of the intermediate transfer body when the toner image on the surface of the intermediate transfer body before the secondary transfer to the recording medium passes through the cleaning member, and the intermediate transfer In an image forming apparatus that is supported so as to be able to come into contact with and separate from the intermediate transfer member surface so as to be in contact with the intermediate transfer member surface when removing the transfer residual toner from the member surface, As serial cleaning member, an image forming apparatus characterized by using a cleaning blade which is brought into contact with the intermediate transfer member surface at the trailing direction. In addition to the cleaning blade, the cleaning device receives a transfer residual toner removed from the surface of the intermediate transfer member by the cleaning blade, and a position where the cleaning blade comes into contact with the surface of the intermediate transfer member. A seal member that abuts on the surface of the intermediate transfer member upstream of the moving direction of the surface and prevents the toner in the cleaning case from scattering, and the base end side of the seal member and the cleaning blade is the cleaning case The cleaning case is positioned on the surface of the intermediate transfer member rather than the contact portion of the seal member with respect to the surface of the intermediate transfer member so that the free end sides of the cleaning blade and the seal member are in contact with and separated from the surface of the intermediate transfer member. At the upstream side of the moving direction of the When the cleaning blade and the seal member are in contact with the surface of the intermediate transfer member, the seal member is first in contact, then the cleaning blade is in contact, and when the cleaning blade and the seal member are separated from the surface of the intermediate transfer member, first the cleaning blade The image forming apparatus according to claim 1, wherein the assembly position of the cleaning blade and the seal member with respect to the cleaning case is set so that the seal member is separated and the seal member is then separated. The image forming apparatus according to claim 1, wherein the driving member that moves the cleaning blade toward and away from the surface of the intermediate transfer member is a cam that is rotationally driven by a predetermined angle range. The image forming apparatus according to claim 2, wherein the driving member that brings the cleaning blade and the seal member into contact with and separates from the surface of the intermediate transfer member includes a cam that is rotationally driven by a predetermined angle range while being pressed against the cleaning case. .

Images