JP4581521B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine and a printer, and more particularly to an image forming apparatus including a transfer conveyance belt that transfers a toner image while electrostatically attracting and conveying a transfer material.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, a photosensitive member (photosensitive drum) formed in a drum shape is uniformly charged, and the photosensitive drum is controlled based on image information. An electrostatic latent image is formed on the photosensitive drum by exposure with the exposed light. The electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is transferred from the photosensitive drum to a transfer material by a transfer device, and then heated and pressed by a fixing device to form the toner image. It is fixed on the transfer material.

In a transfer device used in such an image forming apparatus, in recent years, a transfer conveyance belt is brought into contact with a photosensitive drum, a transfer material is sandwiched in a contact area between the transfer conveyance belt and the photosensitive drum, and the transfer conveyance is performed. A transfer system is employed in which a transfer bias is applied to the belt to transfer the toner image on the photosensitive drum.
In the transfer apparatus using such a transfer conveyance belt, a high-voltage power supply is not required as compared with the conventional corona charging method, so that the apparatus can be downsized and the manufacturing cost can be reduced. In addition, there is an advantage that the generation of ozone is extremely small, and in addition, the transfer performance is stable against dirt caused by adhesion of paper dust or toner. Furthermore, it is possible to configure the transfer conveyance belt unit as a unit so that it can be brought into and out of contact with the photosensitive drum, or to be pulled out from the front side of the image forming apparatus. Jam processing when jamming occurs is easy. In addition, the occupation area of the image forming apparatus can be reduced.

However, in the transfer device using the transfer conveyance belt, the transfer material is directly carried on the transfer conveyance belt and conveyed, so that the toner transferred to the transfer material and the paper powder of the transfer material adhere to the surface of the transfer conveyance belt. easy. When such adhering toner or paper dust accumulates on the surface of the transfer / conveying belt, they may be transferred to a transfer material that is newly transferred / conveyed to contaminate the transfer material, thereby degrading the image quality. Therefore, in such a transfer device, a belt cleaning device for removing toner and paper dust from the surface of the transfer conveyance belt is provided.
In the belt cleaning device, a cleaning brush or a cleaning blade is brought into contact with the surface of the transfer / conveying belt to remove toner or paper dust attached to the surface. The belt cleaning device is sealed at both longitudinal ends of the cleaning brush and the cleaning blade, and seal members are provided to prevent the collected material such as toner and paper dust from leaking into the image forming apparatus. Has been.

  In the belt cleaning device, the paper dust adhering to the surface of the transfer conveyance belt is in the form of fibers. Therefore, when the cleaning blade cleans the surface of the transfer conveyance belt, the paper dust is at the contact portion between the transfer conveyance belt and the cleaning blade. Is easily caught. When paper dust is sandwiched between the contact portions, the surface of the transfer / conveying belt is gradually polished by the sandwiched paper dust, and a minute scratch may be formed on the surface of the transfer / conveying belt. As a result, the surface of the transfer / conveying belt may not be cleaned well, and the transfer material may become dirty. In addition, transfer defects may occur, leading to a decrease in image quality. Therefore, in such a belt cleaning device, the cleaning brush is arranged on the upstream side of the cleaning blade, and the paper dust is removed exclusively by the cleaning brush so that the paper dust is not conveyed to the cleaning blade as much as possible.

Here, as a conventional technique related to a sealing member for sealing the end of the cleaning device, a blade end seal made of Teflon (registered trademark) fiber is fixed to the end of the cleaning blade in the longitudinal direction and scraped off by the blade edge of the blade. There is a technique for suppressing the toner that gradually moves to the longitudinal end portion of the blade by the rotation of the photosensitive member and then falls and scatters into the apparatus (for example, see Patent Document 1).
In addition, as a related art related to the cleaning brush disposed on the upstream side of the cleaning blade, a first region configured by spirally winding a belt-like brush around a shaft, and a configuration where a belt-like brush is spirally wound around a shaft A second region is formed, and the winding direction of the belt-like brush in the second region is formed opposite to the winding direction of the belt-like brush in the first region, so that the collected toner and paper dust can be collected. There is a technique for preventing the ink from being conveyed to the end side in the axial direction and being conveyed to the image area (see, for example, Patent Document 2).

JP 2001-51563 A (page 3-4) JP-A-10-161502 (page 2-3)

  However, since the transfer conveyance belt is stretched around at least one pair of rolls, a belt cleaning device for cleaning the transfer conveyance belt includes a member that supports the belt surface such as the tension roll from the inside. It is also necessary to seal the area facing the unfinished surface. In order to seal a space formed by such an unstable belt surface on which no support member is disposed behind, the longitudinal end of the cleaning blade is simply used as in the technique described in Patent Document 1. There is a problem that a sufficient sealing effect cannot be obtained only by fixing the end seal to the portion.

  Further, the cleaning brush described in Patent Document 2 has a high effect of removing paper dust and is effective. However, in order to clean the transfer conveyance belt while rotating, the cleaning brush particularly in the inside of the belt cleaning apparatus is used. It also has the effect of scattering the collected material in a cloud shape. Therefore, in a belt cleaning device that seals a space formed by an unstable belt surface that is not provided with a support member behind it, if a state where the cloud is excessively filled is formed, an image is formed at the seal portion. It becomes difficult to prevent leakage of toner or the like into the forming apparatus.

  Therefore, the present invention has been made to solve the technical problems as described above, and an object of the present invention is to collect a collected material such as toner in the image forming apparatus in a belt cleaning apparatus for cleaning a belt. It is in suppressing leaking effectively.

  For this purpose, the image forming apparatus of the present invention includes a toner image carrier that carries a toner image, a transfer conveyance belt that transfers the toner image carried by the toner image carrier to a transfer material, and conveys the transfer material. And a cleaning member that extends in a direction perpendicular to the transport direction of the transfer transport belt and cleans deposits adhering to the surface of the transfer transport belt, a support member that supports the cleaning member, and a seal that shields both ends of the cleaning member The member and the support member are configured to be detachable independently of each other, and include a seal support member that supports the seal member and makes contact with the transfer conveyance belt.

  Here, the seal support member can be characterized in that the seal member is brought into contact with the transfer conveyance belt with a substantially uniform intrusion amount. The transfer conveyance belt is configured to be stretched between at least one pair of rolls, and the seal member is a cleaning member straddling a region where the transfer conveyance belt is stretched between the rolls and a region where the transfer conveyance belt linearly moves between the rolls. It can also be characterized by shielding. Furthermore, the seal support member may be arranged such that the support surface for supporting the seal member is substantially parallel to the belt surface in the linearly moving region of the transfer conveyance belt.

  The image forming apparatus of the present invention includes a toner image carrier that carries a toner image, and a transfer conveyance belt that is stretched between at least one pair of rolls, and transfers the toner image carried by the toner image carrier. The transfer conveyance belt that transfers the transfer material to the material and conveys the transfer material, the cleaning brush that rotates while removing the adhering matter adhering to the surface of the transfer conveying belt, and the transfer conveying belt contacts the edge surface to clean the adhering matter. A cleaning blade, and a sealing member that shields an end portion of the cleaning brush and the cleaning blade across a region where the transfer conveyance belt is stretched over the roll and a region where the transfer conveyance belt is linearly moved between the rolls. Is characterized in that the rotational speed is variable.

  Here, the cleaning brush can be configured such that the rotation speed is changed according to the type of transfer material conveyed by the transfer conveyance belt. Further, the cleaning brush may be characterized in that the speed of the surface in contact with the transfer conveyance belt rotates at 1.1 to 1.5 times the conveyance speed of the transfer conveyance belt. Furthermore, the cleaning brush may be configured to rotate in the forward direction with respect to the transfer conveyance belt during image formation, and to rotate in the direction opposite to the conveyance direction during non-image formation. Furthermore, the seal member may be supported independently of the cleaning blade.

  As an effect of the present invention, it is possible to effectively suppress the leakage of the collected material such as the toner from the belt cleaning device into the image forming apparatus, so that the inside of the image forming apparatus is extremely less contaminated with the toner. As a result, it is also possible to form a high-quality image without toner contamination.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. The image forming apparatus shown in FIG. 1 includes a charger 11 that charges the photosensitive drum 10 around the photosensitive drum 10 as an example of a toner image carrier that rotates in the direction of arrow A, and an electrostatic image on the photosensitive drum 10. Laser exposure device 12 for writing the latent image (exposure beam is indicated by Bm in the figure), developing device 13 for storing the toner and making the electrostatic latent image on the photosensitive drum 10 visible with the toner, transfer unit Before the electrostatic transfer at 15, a pre-transfer charger 14 that charges the toner image on the photoconductive drum 10, and a recording paper (paper) P that is a transfer material in the transfer unit 15 for the toner image formed on the photoconductive drum 10. A transfer unit 20 for transferring the toner image, an image density sensor 18 for adjusting an image density disposed in the vicinity of the photosensitive drum 10 on the downstream side of the transfer unit 15, and a charge amount of residual toner after electrostatic transfer is reduced. Chestnut Training electrifier 16 for electrophotography and a drum cleaner 17 which residual toner on the photosensitive drum 10 is removed is provided. Further, a fixing device 60 for fixing the unfixed toner image transferred onto the paper P and a control unit 30 for controlling the operation of each device (each unit) are provided.

  The transfer unit 20 is disposed inside the transfer conveyance belt 21 stretched between the drive roll 22 and the idle roll 23, and is in pressure contact with the photosensitive drum 10 via the transfer conveyance belt 21. And a transfer roll 24. Further, it has a function of transferring the toner image on the photosensitive drum 10 to the paper P conveyed to the transfer unit 15 and a function of conveying the paper P on which the toner image has been transferred in the transfer unit 15 to the fixing device 60. is doing.

  The image forming apparatus according to the present embodiment also includes a paper tray 50 that stores paper P, a pickup roll 51 that picks up and transports the paper P accumulated in the paper tray 50 at a predetermined timing, and a pickup as a paper transport system. A transport roll 52 that transports the paper P fed by the roll 51, a registration roll 54 that feeds the transported paper P to the transfer unit 15 at a predetermined timing, and a transport that guides the paper P transported by the transport roll 52 to the registration roll 54. A chute 53, an inlet chute 55 that guides the paper P fed from the registration roll 54 to the transfer unit 15, and a fixing inlet guide 56 that guides the paper P on which the toner image is transferred by the transfer unit 20 to the fixing device 60 are provided. ing.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. In the image forming apparatus as shown in FIG. 1, image data output from an image reading device (IIT) not shown or a personal computer (PC) not shown is subjected to predetermined image processing by an image processing device not shown. . In the image processing apparatus, the input reflectance data is subjected to predetermined image processing such as various kinds of image editing such as shading correction, position shift correction, gamma correction, frame deletion editing, and movement editing. The image data that has undergone image processing is output to the laser exposure unit 12.

The laser exposure unit 12 irradiates the photosensitive drum 10 with an exposure beam Bm emitted from, for example, a semiconductor laser, according to the input image data. After the surface of the photosensitive drum 10 is charged to a predetermined charging potential by the charger 11, the surface is scanned and exposed by the laser exposure device 12 to form an electrostatic latent image.
The formed electrostatic latent image is developed with a toner image by the developing device 13. That is, for example, a developer carrying body (developing sleeve) 13a carrying a developer composed of toner and carrier is applied with a developing bias composed of a DC voltage from a power source (not shown) or a developing bias in which a DC voltage is superimposed on an AC voltage. Thus, a developing electric field is formed between the photosensitive drum 10. As a result, the toner on the developing sleeve 13a is transferred to the image portion of the electrostatic latent image, and the electrostatic latent image is visualized.

  Here, in the image forming apparatus according to the present embodiment, a setup cycle is executed every predetermined cycle. That is, prior to the actual image forming operation, a predetermined patch area is developed under predetermined conditions. At that time, as will be described later, the transfer conveyance belt 21 of the transfer unit 20 is set to be separated from the photosensitive drum 10. In this state, the developed patch area passes through the transfer section 15 as it is, and the density of the toner image in the patch area is measured by the image density sensor 18 disposed on the downstream side of the transfer section 15. The toner density signal measured by the image density sensor 18 is sent to the control unit 30. Then, in accordance with an instruction from the control unit 30 based on the signal from the image density sensor 18, the charging potential of the photosensitive drum 10 by the charger 11 and / or the developing bias value applied to the developing device 13 is adjusted, and a predetermined image is obtained. The density is set to be maintained.

  Next, the toner image formed on the photosensitive drum 10 in the actual image forming operation is conveyed to the transfer unit 15 where the photosensitive drum 10 and the transfer unit 20 abut. When the toner image is transported to the transfer unit 15, in the paper transport system, the pickup roll 51 rotates in accordance with the timing at which the toner image is transported to the transfer unit 15, and the paper P of a predetermined size is supplied from the paper tray 50. The The paper P supplied by the pickup roll 51 is transported by the transport roll 52, and reaches the registration roll 54 through the transport chute 53. In the registration roll 54, the paper P is temporarily stopped, and the registration roll 54 rotates in accordance with the movement timing of the photosensitive drum 10 carrying the toner image. Thereby, the position of the paper P and the position of the toner image are aligned, and the paper P is sent out from the inlet chute 55 to the transfer unit 15.

  In the transfer unit 15, the sheet P conveyed at the same timing is sandwiched between the photosensitive drum 10 and the transfer roll 24 via the transfer conveyance belt 21 of the transfer unit 20. At that time, a voltage (transfer bias) having a polarity opposite to the charging polarity of the toner (here, negative polarity) is applied to the transfer roll 24, whereby the photosensitive member is transferred from the transfer roll 24 to the transfer conveyance belt 21. A charge having a polarity opposite to the toner charging polarity on the drum 10 is applied. As a result, the unfixed toner image carried on the photoconductor drum 10 is electrostatically transferred onto the paper P in the transfer unit 15 pressed by the photoconductor drum 10 and the transfer roll 24.

Thereafter, the sheet P on which the toner image has been electrostatically transferred is peeled off and conveyed from the photosensitive drum 10 while being electrostatically attracted to the transfer conveyance belt 21 of the transfer unit 20, and downstream of the transfer unit 20 in the sheet P conveyance direction. It is sent to a fixing device 60 provided on the side. When the sheet P is not peeled off from the photosensitive drum 10 and remains adsorbed on the photosensitive drum 10, it is disposed near the surface of the photosensitive drum 10 on the downstream side of the transfer unit 15. The paper P is separated from the photosensitive drum 10 by a separation claw (not shown) and is electrostatically attracted to the transfer conveyance belt 21.
At the rear end of the transfer conveyance belt 21 on the fixing device 60 side, the sheet P is peeled from the transfer conveyance belt 21 due to the curvature when the transfer conveyance belt 21 is wound around the drive roll 22 and the stiffness of the sheet P. Then, the paper P is guided to the fixing inlet guide 56 and conveyed to the fixing device 60.
The unfixed toner image on the paper P conveyed to the fixing device 60 is fixed on the paper P by being subjected to fixing processing by heat and pressure in the fixing device 60. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge mounting portion provided in a discharge portion of the image forming apparatus, and a series of image forming operations is completed.

  The image forming apparatus according to the present embodiment is configured to form a single color toner image. However, the present invention is a color that forms a color toner image by superimposing, for example, yellow, magenta, cyan, and black toner images. It can also be applied to an image forming apparatus.

Next, the transfer unit 20 will be described in detail.
FIG. 2 is a cross-sectional view showing the configuration of the transfer unit 20. As shown in FIG. 2, the transfer unit 20 transfers the toner image on the photosensitive drum 10 onto the paper P, and also transfers the transfer transport unit 20A and the transfer transport unit 20A for transporting the paper P on which the toner image has been transferred. A retract mechanism 20B that contacts and separates from the body drum 10, a cleaning unit 20C as an example of a belt cleaning unit that removes adhering substances such as paper dust and toner attached to the transfer conveyance unit 20A, and a transfer unit for transferring the conveyed paper P 15 includes an inlet chute portion 20 </ b> D leading to 15.

  FIG. 3 is a perspective view showing the configuration of the transfer unit 20. As shown in FIG. 3, the transfer conveyance unit 20 </ b> A of the transfer unit 20 is stretched around the transfer conveyance belt 21 and the transfer conveyance belt 21 arranged in the axial direction of the photosensitive drum 10, and rotates in the arrow B direction. A drive roll 22 that is moved, an idle roll 23 that stretches the transfer conveyance belt 21 to apply a predetermined tension, and a transfer roll 24 that forms a transfer electric field with the photosensitive drum 10 to transfer a toner image onto the paper P. It is comprised by.

As the transfer / conveying belt 21, for example, a chloroprene blend rubber containing an appropriate amount of an antistatic agent such as carbon black is used, and its volume resistivity is set to 10 ⁶ to 10 ⁸ Ωcm. It is a belt. The driving roll 22 is configured such that driving is transmitted by a coupling 25 from a driving motor (not shown) on the image forming apparatus main body side, and rotates the transfer conveyance belt 21 at a predetermined speed. The transfer roll 24 is composed of a tube of EPDM and NBR blend rubber dispersed with carbon on the surface, and a roll of EPDM rubber dispersed with carbon on the inside, and the hardness is set to 25 ° (Asker C), for example. A transfer bias having a polarity (positive polarity) opposite to the toner charging polarity (negative polarity) is stably applied to the transfer roll 24 from a transfer power source (not shown). As a result, a charge having a polarity opposite to the toner charging polarity on the photosensitive drum 10 is applied from the transfer roll 24 to the transfer conveyance belt 21.
In addition, the transfer conveyance unit 20A is configured such that the idle roll 23 side is swung by the retract mechanism unit 20B with the drive roll 22 as the rocking center, and is configured to be able to contact and separate from the photosensitive drum 10.

  Next, the retract mechanism unit 20B is disposed below the transfer conveyance unit 20A. FIG. 4 is a perspective view illustrating a configuration in a state where the transfer conveyance unit 20 </ b> A is removed from the transfer unit 20. As shown in FIG. 4, the retract mechanism unit 20B is disposed at both ends in the width direction of the transfer conveyance unit 20A. The retraction mechanism unit 20B pushes up and down while supporting the idle roll 23 of the transfer conveyance unit 20A. A plate 31 is fixed, and includes a link shaft 32 that swings the contact / separation plate 31, a swing arm 33 that is connected to the center of the link shaft 32, and a DC solenoid 34 that drives the swing arm 33 to swing. Yes. In the retract mechanism 20B, when a current is passed through the direct current solenoid 34, the direct current solenoid 34 moves the swing arm 33 in a downward direction. As a result, the link shaft 32 connected to the swing arm 33 rotates, and the contact / separation plates 31 fixed to both ends of the link shaft 32 swing upward.

  In the transfer unit 20, the transfer conveyance unit 20 </ b> A is set in a state of being separated from the photosensitive drum 10 at the time of measuring the toner image density in the patch area (setup cycle) or in the standby state of the image forming apparatus. FIG. 5 is a diagram illustrating a state where the transfer conveyance unit 20 </ b> A is separated from the photosensitive drum 10. As shown in FIG. 5, during the setup cycle of the image forming apparatus or during standby, the DC solenoid 34 of the retract mechanism unit 20B is not energized, and the swing arm 33 connected to the DC solenoid 34 is pushed up. Is set to the correct position. Therefore, the link shaft 32 connected to the swing arm 33 positions the contact / separation plates 31 fixed to both ends of the link shaft 32 downward. Since both ends of the idle roll 23 of the transfer conveyance unit 20A are supported by the contact / separation plate 31, the transfer conveyance unit 20A is set in a state of being separated from the photosensitive drum 10 by the contact / separation plate 31.

  On the other hand, during a normal image forming operation, the transfer conveyance unit 20A is set in a state of being in contact with the photosensitive drum 10. FIG. 6 is a diagram illustrating a state where the transfer conveyance unit 20 </ b> A is in contact with the photosensitive drum 10. During the image forming operation, the paper P that has been fed to the registration roll 54 and has been waiting is sent out by the registration roll 54 in accordance with the movement timing of the photosensitive drum 10 carrying the toner image. At that time, the sensor (not shown) detects that the leading end of the paper P is guided to the inlet chute 55 and has reached the vicinity of the contact portion between the photosensitive drum 10 and the transfer conveyance belt 21. When the control unit 30 inputs a signal from this sensor, the control unit 30 turns on the DC solenoid 34 of the retract mechanism unit 20B and starts energization. As a result, the DC solenoid 34 moves the swing arm 33 in a downward direction. When the swing arm 33 is pushed down, the link shaft 32 connected to the swing arm 33 rotates, and the contacting / separating plates 31 fixed to both ends of the link shaft 32 swing upward. Then, the idle roll 23 of the transfer conveyance unit 20 </ b> A whose both end portions are supported by the contact / separation plate 31 is set in a state of being in contact with the photosensitive drum 10. At that time, a nip portion is formed at a contact portion between the photosensitive drum 10 and the transfer conveyance belt 21.

  When the transfer conveyance unit 20 </ b> A comes into contact with the photosensitive drum 10, the paper P on the transfer conveyance belt 21 conveyed by the rotation drive of the drive roll 22 enters the nip portion between the photosensitive drum 10 and the transfer conveyance belt 21. A transfer bias having a polarity (positive polarity) opposite to the toner charging polarity (negative polarity) is applied to the transfer roll 24 from a transfer power source (not shown). As a result, a charge having a polarity opposite to the toner charging polarity on the photosensitive drum 10 is applied to the transfer / conveying belt 21. Then, the toner on the photosensitive drum 10 is transferred to the paper P. Thereafter, the paper P is transported in a state of being electrostatically attracted to the transfer transport belt 21 and sent to the fixing device 60.

The inlet chute 20D is disposed upstream of the transfer conveyance unit 20A in the transfer unit 20, and is integrally joined to the housing 70. The photosensitive drum inlet chute 55a integrally formed with the photosensitive drum unit that supports the photosensitive drum 10 and the resist roll inlet chute 55b integrally formed with the resist roll unit that supports the resist roll 54 (FIG. Inlet chute 55 is configured in combination with an upper inlet chute consisting of 1). In this case, the inlet chute 20D constitutes the lower inlet chute of the inlet chute 55. That is, the inlet chute 55 is composed of a separate upper inlet chute and lower inlet chute, and the lower inlet chute is integrally configured with the transfer unit 20 as an inlet chute portion 20D.
The inlet chute 55 supports one surface (lower surface) of the sheet P conveyed from the resist roll 54 by the inlet chute 20D, and the other surface (upper surface) of the photosensitive drum inlet chute 55a and the resist roll. While being regulated by the inlet chute 55b, it is carried into the nip portion between the photosensitive drum 10 and the transfer conveyance belt 21 in the transfer portion 15 while maintaining an accurate posture without being inclined.

Next, the cleaning unit 20C will be described.
As shown in FIG. 2, the cleaning unit 20 </ b> C includes a cleaning brush 41 as an example of a cleaning member that wipes off adhering matter such as paper dust and toner adhered on the surface of the transfer conveyance belt 21 of the transfer conveyance unit 20 </ b> A. A flicker bar 42 disposed so as to bite into the cleaning brush 41 so as to knock off the adhering matter adhering to the cleaning brush 41, disposed downstream of the cleaning brush 41 in the transport direction of the transfer transport belt 21, and transferred to the transfer transport belt 21. A cleaning blade 43 as an example of a cleaning member that scrapes off deposits on the surface, a cleaning brush 41, a cleaning box 44 that receives paper dust or toner removed from the surface of the transfer conveyance belt 21 by the cleaning blade 43, and inside the cleaning box 44 Paper dust and A recovery coil 45 that conveys the toner to a recovery bottle (not shown), a blade holder 46 as a support member for supporting the cleaning blade 43, a shield seal 47 that is held by the blade holder 46 and shields the downstream side of the cleaning blade 43, Furthermore, it is comprised by the side seal 48 (not shown in FIG. 2) as a sealing member which seals the both ends of the cleaning part 20C.

The cleaning brush 41 is a brush roll in which brush fibers made of conductive polyester (electric resistance 10 ⁵ to 10 ⁶ Ω) having a thickness of 5.7 denier and a fiber density of 30 K / inch ² are formed on the surface. The transfer conveyance belt 21 is configured to rotate in the forward direction and the conveyance direction. Further, the brush fibers of the cleaning brush 41 are formed so as to be inclined in the forward direction with respect to the conveyance direction of the transfer conveyance belt 21. On the other hand, the cleaning blade 43 is a plate-like member made of urethane rubber having a thickness of 1 mm, for example, and is disposed in counter contact with the transfer conveyance belt 21. The cleaning brush 41 wipes off adhering material such as paper dust and toner adhering to the surface of the transfer conveyance belt 21 while rotating in the forward direction with respect to the transfer conveyance belt 21 during image formation. Is collected in the cleaning box 44 from the surface of the transfer conveyance belt 21. Further, the cleaning blade 43 disposed on the downstream side of the cleaning brush 41 scrapes off deposits that could not be wiped off by the cleaning brush 41 and collects them in the cleaning box 44. In particular, when the adhesion force of the adhered matter to the transfer / conveying belt 21 is strong as in the case of using a polymer toner having a small particle size as the toner, the effect of reducing the adhesion force due to contact with the cleaning brush 41 and the cleaning Due to a synergistic effect with the scraping effect of the blade 43, the deposits can be sufficiently removed.

  Further, the collection coil 45 conveys paper dust, toner, and the like in the cleaning box 44 to a collection bottle (not shown) outside the transfer unit 20 while rotating in the direction of arrow C in FIG. The collecting coil 45 is moved in the direction of arrow C, that is, in the direction away from the fixing device 60 side of paper dust and toner collected on the bottom surface of the cleaning box 44 (upstream side in the direction of conveying the paper P of the transfer conveying belt 21). By rotating so as to be moved, paper dust, toner, and the like are conveyed along the side wall 44a in the cleaning box 44 on the side opposite to the fixing device 60 side. Therefore, the collected toner is difficult to receive heat from the fixing device 60, and the fusion between the toners can be suppressed. Therefore, the collected paper powder, toner, and the like can be smoothly conveyed to the collection bottle. .

  Here, FIG. 7 is a plan view showing one end region of the cleaning unit 20C. As shown in FIG. 7, at both ends of the cleaning unit 20C, there are space areas for removing deposits such as paper dust and toner from the surface of the transfer conveyance belt 21 by the cleaning brush 41 and the cleaning blade 43, and the transfer conveyance belt. A side seal 48 that shields the space region from the cleaning blade 43 to the shielding seal 47 in the conveying direction 21 and seals the inside is provided. The side seal 48 is formed of brush fibers made of a resin such as polypropylene. The side seal 48 is disposed so as to overlap the end edge surface of the transfer / conveyance belt 21, and is formed so as to follow the outer surface of the transfer / conveyance belt 21, thereby shielding the outside. That is, in the region where the transfer conveyance belt 21 is stretched around the drive roll 22 and has a curved shape, the transfer conveyance belt 21 is formed in a curved shape following this curve, and in the region moving away from the drive roll 22 in a straight line, it is linear. Is formed.

FIG. 8 is a cross-sectional view of the end of the cleaning unit 20C where the side seal 48 is disposed. As shown in FIG. 8, the side seal 48 is supported by a seal holder 49 as a seal support member configured separately (separate parts) from the blade holder 46 that holds the cleaning blade 43 and the shielding seal 47. . Therefore, the seal holder 49 is configured to be detachable from the cleaning unit 20 </ b> C independently of the blade holder 46.
Further, in the seal holder 49, the support surface 49a that supports the side seal 48 is formed as a flat surface. The support surface 49a of the seal holder 49 has an equal distance from the transfer conveyance belt 21 with respect to an area (linear area) where the transfer conveyance belt 21 moves linearly between the drive roll 22 and the idle roll 23. Is arranged. By disposing in this way, the side seal 48 formed with a constant thickness contacts the linear region of the transfer conveyance belt 21 with a substantially uniform intrusion amount of, for example, 0.5 to 1.5 mm. Accordingly, the side seal 48 effectively seals a space region from the cleaning blade 43 to the shielding seal 47 in the transfer direction of the transfer conveyance belt 21.

  On the other hand, in the region (curved region) where the transfer conveyance belt 21 is stretched around the drive roll 22, the side seal 48 is not supported by the seal holder 49, and a pressing member (not shown) separate from the seal holder 49. ) To follow the curved area of the transfer conveyance belt 21. Thus, since the back surface is supported by the drive roll 22 in the curved region of the transfer conveyance belt 21, it is formed with a constant thickness by being pressed by the pressing member whose setting accuracy is relatively rough. The side seal 48 thus made can be brought into contact with the curved region of the transfer conveyance belt 21 with a substantially uniform intrusion amount. As a result, the side seal 48 seals a space area in which the cleaning brush 41 and the cleaning blade 43 remove deposits such as paper dust and toner from the surface of the transfer conveyance belt 21.

  As described above, the cleaning unit 20 </ b> C of the present embodiment is configured such that the side seal 48 is supported by the seal holder 49, which is a separate member from the blade holder 46, and abuts against the transfer conveyance belt 21. With this configuration, the side seal 48 can be brought into contact with the transfer / conveying belt 21 with a substantially uniform intrusion amount. In particular, the side seal 48 can be brought into contact with the linear region of the unstable transfer conveyance belt 21 in which no support member is provided on the back surface with a substantially uniform intrusion amount. Therefore, it is possible to suppress leakage of the collected toner from the cleaning unit 20C, and to suppress deterioration of image quality due to toner contamination in the apparatus and toner adhering to the paper P.

In other words, conventionally, the side seal 48 is generally attached to the blade holder 46 that holds the cleaning blade 43. When attached to the blade holder 46, the blade holder 46 is formed at an angle in order to bring the cleaning blade 43 into counter contact with the transfer conveyance belt 21, so that the side seal 48 is attached to the transfer conveyance belt 21. However, it is difficult to make contact with a uniform intrusion amount. Therefore, a gap is likely to be generated at the contact portion between the side seal 48 and the transfer conveyance belt 21, and the toner may leak out.
On the other hand, in the side seal 48 of the present embodiment, the side seal 48 is held by the seal holder 49 configured separately (separate parts) from the blade holder 46 that holds the cleaning blade 43 and the shielding seal 47, Independent of the setting of the blade holder 46, the seal holder 49 can be positioned independently. For this reason, the side seal 48 can be arranged with high accuracy so as to contact the transfer conveyance belt 21 with a substantially uniform intrusion amount, and therefore an unstable belt in which no support member is arranged behind. Even in the space formed by the surface (the linear region of the transfer / conveying belt 21), a configuration in which a gap is not easily generated can be realized, and toner leakage can be suppressed.

Further, the side seal 48 is held by a separate seal holder 49 from the blade holder 46 so that the side seal 48 can be detached from the cleaning unit 20C independently of the blade holder 46, so that only the side seal 48 is replaced alone. can do. Therefore, it is not necessary to replace the cleaning blade 43 at the same time, so that maintenance can be easily performed and maintenance costs can be reduced.
Furthermore, even if the cleaning blade 43 needs to be replaced due to wear of the cleaning blade 43 or the like, the side seal 48 can be reused separately.
In addition, since the side seal 48 can be brought into contact with the transfer / conveying belt 21 with a uniform intrusion amount, the contact pressure of the side seal 48 against the transfer / conveying belt 21 is substantially the entire contact portion. It becomes uniform. For this reason, the variation in the contact pressure at the contact portion between the side seal 48 and the transfer conveyance belt 21 is extremely small. Therefore, the force that biases the transfer conveyance belt 21 to any one end due to the nonuniform contact pressure. Can be suppressed. Accordingly, it is possible to suppress the occurrence of a deviation (belt walk) of the transfer conveyance belt 21.

Next, rotation of the cleaning brush 41 will be described. As described above, the cleaning brush 41 is configured to contact the transfer conveyance belt 21 while rotating. Then, during the image forming operation, the brush fibers formed on the transfer conveyance belt 21 in the forward direction while rotating in the forward direction with respect to the transfer conveyance belt 21 are formed on the surface of the transfer conveyance belt 21 by the brush fibers that are inclined in the forward direction with respect to the transfer conveyance belt 21 conveyance direction. Wipe off adhering substances such as paper dust and toner. At that time, the cleaning brush 41 of the present embodiment is configured so that the rotation speed of the cleaning brush 41 can be changed.
Specifically, the cleaning brush 41 is configured to be able to set a different rotation speed depending on the paper type of the paper P. This is because the amount of paper dust adhering to the transfer conveyance belt 21 varies depending on the paper type of the paper P carried on the transfer conveyance belt 21, and the rotation speed is set in accordance with the amount of paper dust of the paper P. is there. By increasing the rotation speed of the cleaning brush 41, it is possible to increase the paper powder collecting ability of the cleaning brush 41. However, on the other hand, increasing the rotational speed of the cleaning brush 41 increases the amount of toner cloud in the cleaning box 44. Therefore, even when the paper P with a small amount of paper dust is used, setting the rotation speed of the cleaning brush 41 fast increases the amount of toner cloud in the cleaning box 44 unnecessarily, and toner leakage into the machine is possible. It will increase the sex. In particular, in a configuration in which a space formed by an unstable belt surface (a linear region of the transfer conveyance belt 21) in which no support member is disposed behind is sealed by the side seal 48, the possibility of toner leakage increases. It will be. Therefore, an optimal cleaning condition for each paper P is set by balancing the paper powder collecting ability of the cleaning brush 41 with the amount of toner cloud to be generated.

The rotation speed of the cleaning brush 41 can be set by a user instruction from an operation panel (not shown) which is a user interface of the image forming apparatus. In this case, when the user selects the type of paper P to be used from the operation panel, the paper type designation signal is transmitted to the control unit 30. Then, the control unit 30 instructs the rotation speed corresponding to the paper type, and rotates the cleaning brush 41 at the optimum rotation speed.
Further, for each of the plurality of paper trays 50, the size and paper type of the paper P to be set are registered in the control unit 30 in advance by the user or set as defaults, and the user can set the paper tray from the operation panel. By selecting 50, the control unit 30 can also be configured to set the rotational speed of the cleaning brush 41 corresponding to the selected paper tray 50.
Furthermore, when the paper P is loaded in the paper tray 50 and loaded in the image forming apparatus, the control unit 30 can display on the operation panel a request for the user to specify the paper type. . At that time, a plurality of paper types may be displayed on the operation panel, and the user may select from among them. In the case of manual sheet feeding, different settings can be made separately.

Here, as the rotational speed of the cleaning brush 41, the surface speed of the cleaning brush 41 is preferably variable between 1.1 and 1.5 times the transport speed of the transfer transport belt 21. FIG. 9 is a diagram comparing the rotation speed of the cleaning brush 41 and the amount of paper dust. The amount of paper dust is obtained by measuring the amount of paper dust accumulated (unit density of paper dust) per unit length of paper dust captured by the cleaning blade 43 disposed downstream of the cleaning brush 41 after cleaning. is there. The measurement was performed by counting the number of paper dust with a microscope. In FIG. 9, when the surface speed of the cleaning brush 41 and the transport speed of the transfer transport belt 21 are constant, the peripheral speed ratio (the surface speed of the cleaning brush 41 / the transport speed of the transfer transport belt 21) is 1. In this case, the accumulated paper powder density is expressed as a relative value where the density is 1. FIG. 9 shows the results of using the cleaning brush 41 made of polypropylene and the polyester made of polyester as the brush fibers.
As shown in FIG. 9, in both the polypropylene brush and the polyester brush, the paper brush removal performance by the cleaning brush 41 is improved at a peripheral speed ratio of 1.1 or more, and the peripheral speed ratio is 1.5. The improvement effect is almost saturated. Therefore, it is preferable that the rotational speed of the cleaning brush 41 is variable between the peripheral speed ratios of 1.1 to 1.5 times in consideration of the amount of toner cloud generated by the cleaning brush 41.

The cleaning brush 41 is set to rotate in the forward direction with respect to the transfer direction of the transfer conveyance belt 21 during the image forming operation, and to rotate in the direction opposite to the transfer direction of the transfer conveyance belt 21 except during the image formation operation. It is also possible.
FIG. 10 is a schematic diagram illustrating a configuration for driving the cleaning brush 41. A stepping motor 27 is connected to the cleaning brush 41 via a gear train 28. The stepping motor 27 is disposed separately from the drive motor 26 connected to the drive roll 22 that rotates the transfer conveyance belt 21 via the coupling 25. That is, the cleaning brush 41 is rotated by a drive mechanism that is different from the drive roll 22 that drives the transfer conveyance belt 21.

A sensor (not shown) that detects the passage of the paper P is disposed between the transfer conveyance belt 21 and the fixing entrance guide 56 that guides the paper P to the fixing device 60, and this sensor detects the passage of the paper P. The control unit 30 controls the stepping motor 27 to rotate the cleaning brush 41 in the reverse direction. Then, after reverse rotation for a predetermined time, the control unit 30 controls the stepping motor 27 to switch the rotation of the cleaning brush 41 in the forward direction. When the paper P detected by the sensor is the final paper P in the image forming cycle, the control unit 30 controls the stepping motor 27 to stop.
In this way, by rotating the cleaning brush 41 backward after passing the paper P, the brush fibers formed in the forward direction with respect to the transport direction of the transfer transport belt 21 in the cleaning brush 41 are inverted by the flicker bar 42. Therefore, it is possible to remove the collected matter such as toner and paper dust accumulated between the brush fibers and to correct the fall of the brush fibers. Thereby, the cleaning performance of the cleaning brush 41 can be maintained over a long period of time.

  As described above, in the image forming apparatus of the present embodiment, in the cleaning unit 20C that cleans the transfer conveyance belt 21 of the transfer unit 20, the side seal 48 that shields both ends of the cleaning unit 20C and seals the inside is provided. The blade holder 46 is supported by a seal holder 49, which is a separate member, and is configured to come into contact with the transfer conveyance belt 21. With this configuration, the seal holder 49 can be independently set independently of the setting of the blade holder 46, so that the side seal 48 has a substantially uniform intrusion amount with respect to the transfer conveyance belt 21. It is possible to arrange with high accuracy so as to abut. In particular, the side seal 48 can be brought into contact with the linear region of the unstable transfer conveyance belt 21 in which no support member is provided on the back surface with a substantially uniform intrusion amount. Therefore, it is possible to suppress leakage of the collected toner from the cleaning unit 20C, and to suppress deterioration of image quality due to toner contamination in the apparatus and toner adhering to the paper P.

  Further, the cleaning brush 41 provided in the cleaning unit 20 </ b> C is configured to be able to set a different rotation speed depending on the paper type of the paper P. Accordingly, it is possible to achieve a balance between the paper dust collection capability of the cleaning brush 41 and the amount of toner cloud generated during cleaning. For this reason, a structure formed by the side seal 48 is used to seal a space formed by an unstable belt surface (a linear region of the transfer conveyance belt 21) in which a supporting member is not disposed at the back while maintaining a paper dust collecting capability. In this case, it is possible to realize a configuration with extremely low possibility of toner leakage.

  Examples of utilization of the present invention include application to copying machines, printers, facsimiles, and multifunctional machines using electrophotography.

1 is a schematic configuration diagram of an image forming apparatus of the present invention. It is sectional drawing which shows the structure of a transfer unit. It is a perspective view which shows the structure of a transfer unit. FIG. 3 is a perspective view illustrating a configuration of a transfer unit in a state where a transfer conveyance unit is removed. FIG. 6 is a diagram illustrating a state where a transfer conveyance unit is separated from a photosensitive drum. FIG. 6 is a diagram illustrating a state where a transfer conveyance unit is in contact with a photosensitive drum. It is the plane block diagram which showed one edge part area | region of the cleaning part. It is sectional drawing of the edge part by which the side seal of the cleaning part was arrange | positioned. It is the figure which compared the rotational speed of cleaning brush, and the amount of paper dust. It is the schematic which showed the structure which drives a cleaning brush.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Photosensitive drum, 11 ... Charger, 12 ... Laser exposure device, 13 ... Developing device, 15 ... Transfer part, 17 ... Drum cleaner, 20 ... Transfer unit, 20A ... Transfer conveyance part, 20B ... Retract mechanism part, 20C DESCRIPTION OF SYMBOLS Cleaning part, 20D ... Inlet chute part, 21 ... Transfer conveyance belt, 22 ... Drive roll, 23 ... Idle roll, 25 ... Coupling, 27 ... Stepping motor, 30 ... Control part, 31 ... Contacting / separating plate, 32 ... Link Shaft, 33 ... swing arm, 34 ... DC solenoid, 41 ... cleaning brush, 42 ... flicker bar, 43 ... cleaning blade, 44 ... cleaning box, 45 ... collection coil, 46 ... blade holder, 47 ... shielding seal, 48 ... Side seal 49 ... Seal holder 54 ... Registration roll 55 ... Inlet shoe Doo, 60 ... fuser

Claims (5)

A toner image carrier for carrying a toner image;
A transfer conveyance belt configured to be stretched around at least a pair of rolls, transferring a toner image carried by the toner image carrier to a transfer material, and conveying the transfer material;
A cleaning member that extends in a direction perpendicular to the transfer direction of the transfer conveyance belt and cleans deposits adhered to the surface of the transfer conveyance belt;
A support member for supporting the cleaning member;
The transfer / conveying belt is stretched over one of the pair of rolls and formed over a first region having a curved shape and a second region moving linearly between the pair of rolls, and the cleaning A sealing member that seals a space region in which the member removes the deposits from the transfer conveyance belt ;
The support member is configured separately from the support member, and has a support surface disposed so as to be substantially parallel to the belt surface of the second region. A seal support member for supporting the seal member and bringing the seal member into contact with the second region ;
A pressing member configured to be separated from the seal support member and pressing the seal member in the first region so as to follow the first region. Image forming apparatus. The cleaning member is configured to have a variable rotation speed, and cleans the adhering matter adhering to the surface of the transfer / conveying belt while rotating, and the adhering surface is brought into contact with the transfer / conveying belt to clean the adhering matter. The image forming apparatus according to claim 1, further comprising a cleaning blade. The image forming apparatus according to claim 2 , wherein a rotational speed of the cleaning brush is changed according to a type of the transfer material conveyed by the transfer conveyance belt. 3. The image forming apparatus according to claim 2 , wherein the cleaning brush rotates at a speed of a surface in contact with the transfer conveyance belt of 1.1 to 1.5 times the transfer speed of the transfer conveyance belt. apparatus. The image forming apparatus according to claim 2 , wherein the cleaning brush rotates in a forward direction with respect to a conveyance direction of the transfer conveyance belt during image formation, and rotates in a direction opposite to the conveyance direction during non-image formation.

Images