JP2010217528A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve belt replaceability and to easily suspend a belt in a correct position. <P>SOLUTION: In an image forming apparatus having an endless belt, an abutment part is freely protruded/retracted in conjunction with a tension mechanism, and the abutment part is retracted when tension is applied while the abutment part is protruded when tension is released. The image forming apparatus includes a detection means detecting the position of the belt edge, and as the abutment part is disposed in the substantially center of a detection area, belt positioning is set easily when an old belt is replaced with a new one. Since the abutment part is positioned in the substantially center of the edge sensor detection area, the belt is driven in a favorable position from the beginning of starting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus (hereinafter referred to as an image forming apparatus) such as a copying machine, a printer, a facsimile machine, and a multifunction machine using an electrophotographic system.

  Conventionally, color image forming apparatuses having various configurations have been proposed. As one of them, an electrophotographic method is adopted, and an image forming unit is provided for each color developer. An image forming apparatus that forms a visible image for each color in a well-known image forming process on a photosensitive drum as a body, and the visible image created in each image forming unit is wound around a plurality of rollers, Transfer is sequentially performed on a so-called intermediate transfer belt which is endlessly circulated by the rotation. Further, there is a color image forming apparatus of an in-line intermediate transfer system that obtains a color image by performing batch transfer on a sheet supplied from the outside as a recording medium and fixing it. In such an intermediate transfer type image forming apparatus, an intermediate transfer member belt used as an intermediate transfer member may have an image defect due to a change in resistance value or deterioration of surface properties due to durability deterioration or the like. There is sex. Therefore, the intermediate transfer belt needs to be replaced with a new one in order to maintain a desired image quality when a predetermined life is reached.

  Further, during the operation of the image forming apparatus, these intermediate transfer belts have a problem that the intermediate transfer belt is displaced due to misalignment of the suspension roller of the belt due to distortion of the main body of the apparatus. ing. As a means for correcting the belt deviation, for example, a method of detecting the belt deviation amount by detecting the position of the belt end and correcting the alignment of one of the rollers based on this information is adopted. It is done. According to this method, the mechanical stress is less and the life of the belt can be reduced compared to the means for regulating the rib-shaped rubber part affixed to the belt edge or regulating the belt edge by directly abutting against the flange or the like. Although it can be greatly improved, since it is a system for detecting the position of the belt end, it is necessary to position the thrust position of the belt with high accuracy.

  However, the operation of attaching such a belt body to the apparatus main body requires skill, and there is a possibility that an attachment failure may occur in some cases. In particular, since the positioning in the thrust direction is stretched at a predetermined position by visual observation, it is difficult to position with high accuracy.

  In Patent Document 1, in order to prevent the belt and the edge sensor from interfering when the belt is attached, a drawer that can be freely inserted into and removed from the main body of the image forming apparatus is provided, and an intermediate transfer belt is attached to the drawer. Contains the belt module including. When exchanging the intermediate transfer belt, the belt module to which the intermediate transfer belt is attached is separated from each photosensitive drum so that the belt module can be moved up and down in the drawer. Then, in conjunction with the vertical movement of the belt module in the drawer, an edge contact member provided on the second edge sensor attached to the belt module is brought into contact with the intermediate transfer body belt, and the intermediate transfer body belt It is configured to be separated from. The edge contact part is swingable, detects the reflected light, detects the swing position of the upper end of the edge contact member, detects the edge position of the belt, and retracts when replacing the belt. To prevent interference with the belt.

JP 2006-267500 A

  However, since the positioning in the thrust direction at the time of belt replacement is stretched at a predetermined position by visual observation, the positioning is difficult. In particular, although the belt tension is relaxed, positioning in the thrust direction on the slack side is difficult, and if the belt tension is increased, the belt may be stretched in a kinked state. When the twisted belt is driven, the belt moves in the thrust direction, which causes a positional shift or a color shift of the image in the main scanning direction. For this reason, it is necessary to perform the steering control with the belt being brought to an equilibrium state to some extent, and there is a problem that it has an extra belt shift control time and delays the startup time of the apparatus.

  In addition, the belt may reach the side surface of the apparatus due to excessive deviation and the end portion may be damaged.

  In addition, the edge sensor and the edge contact portion require high accuracy, but there is a problem of increasing the cost of the unit by maintaining accuracy by making it swingable.

  Further, since the position of the belt to be set is not always the best position, there is a problem that the start-up time of the device for correction is delayed by belt steering control.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
An image forming apparatus comprising: an endless belt; a driving roller that drives the endless belt; and a tension roller that applies tension to the endless belt. The tension roller includes a plurality of abutting members that abut against the endless belt. A tension mechanism movable to a first position where tension is applied to the endless belt and a second position where the endless belt can be inserted and removed;
The abutting member can freely move in and out in conjunction with the tension mechanism of the tension roller. In the first position, the abutting member retreats to the abutting position, and in the second position, the abutting member projects from the abutting position. Including doing.

Furthermore, it has a detection means which detects the position of the edge part of the said endless belt, The abutting position of the said abutting part includes arrange | positioning in the approximate center of the detection area | region of the said detecting means.

Furthermore, the plurality of abutting portions protrude from a tension side and a loose side of the endless belt suspended from the drive roller and the tension roller.

Furthermore, when the tension of the tension roller is loosened, the abutting portions overlap the endless belt.

Further, it includes enabling the endless belt to be inserted and removed when the tension of the tension roller is loosened.

Further, the endless belt includes a transfer belt for transferring an image to transfer paper.

  According to the present invention, when replacing the old and new belts, the belt abutment portion protrudes by loosening the belt tension, so that the belt positioning set can be easily completed.

  In addition, since the abutting portion is almost in the middle of the edge sensor detection area, the belt can be driven at a good position from the start-up stage.

  In addition, since a plurality of abutting portions are arranged and arranged on the loose side of the belt, it can be easily set at the correct position.

  Further, since the abutting portions sufficiently overlap, it is possible to prevent the belt from being kinked due to the abutting failure, to prevent the belt from shifting, and to prevent the belt from being damaged.

1 is a cross-sectional view of a color digital printer shown as an embodiment of an image forming apparatus of the present invention. FIG. 3 is a cross-sectional view illustrating an intermediate transfer body unit according to the present embodiment. FIG. 3 is a cross-sectional view illustrating an intermediate transfer body unit according to the present embodiment. FIG. 3 is a cross-sectional view illustrating an intermediate transfer body unit according to the present embodiment. FIG. 3 is a plan view showing an intermediate transfer member unit of the present embodiment. Explanatory drawing which shows the steering mechanism of this embodiment. Explanatory drawing which shows the belt edge part position sensor of this embodiment. The block diagram which shows the steering control of this embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an image forming apparatus according to the invention will be described in detail with reference to the drawings.

  FIG. 1 shows a color digital printer as a specific example of the image forming apparatus. The surface of each of the four photosensitive drums 101a to 101d is charged with a uniform charge by charging rollers 102a to 102d. Each of the laser scanners 103a to 103d receives yellow (Y), magenta (M), cyan (C), and black (K) image signals, and irradiates the drum surface with laser light in accordance with the image signals, and charges Is neutralized to form a latent image. The latent image formed on the photosensitive drum is developed with yellow, magenta, cyan, and black toners by developing units 104a to 104d. The toner developed on each photosensitive drum is sequentially transferred to an intermediate transfer body belt 106, which is an endless belt-like image carrier, by primary transfer rollers 105a to 105d, and a full color toner image is formed on the intermediate transfer body belt 106. It is formed. Transfer residual toner on the photosensitive drum is collected by drum cleaners 107a to 107d.

  On the other hand, a sheet, which is a transfer material, such as recording paper fed from any of the paper feed cassettes 111 and 112 or the manual feed unit 113 is conveyed by the conveyance roller 114 toward the registration roller 115. After the leading edge of the sheet comes into contact with the stopped registration roller 115 to form a loop, the registration roller 115 starts to rotate in synchronization with the toner image on the intermediate transfer belt 106.

  The toner image on the intermediate transfer belt 106 is transferred to the sheet by the secondary transfer outer roller 109 and is fixed on the sheet by heating and pressing with the fixing device 110. Thereafter, the sheet is discharged from the discharge portions 116a and 116b to the outside of the apparatus main body. Further, the transfer residual toner on the intermediate transfer belt 106 that has not been transferred in the secondary transfer portion is collected by the intermediate transfer body cleaner 108.

  FIG. 2 shows the intermediate transfer body unit 1 including a support frame 10 that supports the intermediate transfer body belt 106 so that the intermediate transfer body belt 106 can be turned and rotated. The intermediate transfer body unit 1 can be detached and attached from the main body of the image forming apparatus. The intermediate transfer belt 106 is wound between each of the driving roller 11, the tension roller 12, and the secondary transfer inner roller 13 that are rotatably supported by the support frame 10. Further, the primary transfer rollers 105 a to 105 d are rotatably supported by bearings, and the bearings are urged by the springs 14 so that the primary transfer rollers are pressed against the inner surface on the back side of the intermediate transfer belt 106.

  When the intermediate transfer body unit 106 is mounted on the apparatus main body of the image forming apparatus, a driving gear coupled to the roller end of the driving roller 11 is connected to a driving system provided on the apparatus main body side, and the arrow in FIG. A clockwise rotation indicated by A is received. When the drive roller 11 rotates, the intermediate transfer belt 106 is rotated by a rotational friction force. The primary transfer rollers 105a to 105d are in pressure contact with the photosensitive drum 101 with the intermediate transfer belt 106 interposed therebetween, and are driven to rotate as the intermediate transfer belt 106 travels.

  FIG. 3 is a view showing a tension mechanism, a butting mechanism, and a steering mechanism for the intermediate transfer belt 106 of the intermediate transfer unit 1. The tension roller 12 is driven by the intermediate transfer belt 106 around the shaft 12a, and tension is applied to the intermediate transfer belt 106 by a spring (not shown). The arm 12b is pivotally supported, and an eccentric cam 51 is provided at the rotation center 51a of the arm 12b. By swinging the arm 12b, it is possible to tension or loosen the tension. The arm 12b can be fixed in a tensioned state with a screw (not shown), and can be swung by loosening the screw. FIG. 3 shows a state in which a tension is applied, and FIG. 4 shows a state in which the tension is loosened. As shown in FIG. 4, the tension of the intermediate transfer belt 106 can be relaxed by swinging the arm 12b downward (reference numeral 80) in the figure.

  A slider 52 is in contact with the cam 51. As the cam 51 rotates, the slider 52 is movable in the horizontal direction (reference numeral 84) in the figure. Belt contact plates 53, 54, and 55 are connected to the slider 52. Reference numerals 53a, 54a, and 55a are rotation centers of the belt contact plates, and contact the fixed shafts 53b, 54b, and 55b. As the slider 52 moves in the lateral direction, the belt contact plates 53, 54, 55 swing (reference numerals 81, 82, 83), and the end of the belt contact plate protrudes. That is, the belt contact plates 53, 54, and 55 swing in conjunction with the swing of the arm 12b. Therefore, when the tension of the intermediate transfer belt 106 is loosened, the belt contact plate as the belt contact portion protrudes by swinging the arm 12b. On the contrary, when the tension of the intermediate transfer belt 106 is tensioned, the belt contact plate is accommodated.

  Reference numeral 50 denotes a belt end position detection sensor, which is disposed at the end of the intermediate transfer belt 106. The drive roller 11 includes a belt steering mechanism that drives the intermediate transfer belt 106 in the A direction and can move in the thrust direction of the drive roller. One side supporting the drive roller is moved in the S direction in the drawing to drive the intermediate transfer belt 106 in the A direction, thereby enabling control of movement in the thrust direction.

  The configuration of the belt position detection sensor 50 is shown in FIG. A distance L is measured by a reflective optical distance sensor 70 with respect to a swingable flag 72 having a belt contact portion 71 that contacts an end portion of the intermediate transfer belt 106. From the distance L, the position of the intermediate transfer belt 106 is determined. Further, the flag 72 is brought into contact with the end of the intermediate transfer belt 106 by a spring (not shown), and follows the end of the intermediate transfer belt 106 during rotation to measure the position. The belt position detection sensor 50 is fixed to the frame 10 and is independent of the tension abutting mechanism and the steering mechanism, and is fixed to the frame 10 to ensure position detection accuracy.

  A steering mechanism is shown in FIG. The drive roller 11 can be tilted on one side in the S direction. The arm 71 that pivotally supports the drive roller 11 has a swinging center 72 and is always in contact with the eccentric cam 70, and the arm 71 follows the outer periphery of the cam 70. The cam 70 is rotationally driven by a steering motor 73. The steering motor 73 is connected to the steering controller 80. FIG. 8 is a block diagram of the steering control. Based on the output signal of the belt position detection sensor 50, the controller 80 drives the steering motor 73 by a predetermined clock, tilts the drive roller 11, and performs belt steering control. Yes.

  Next, replacement of the intermediate transfer belt 106 will be described with reference to FIG. The intermediate transfer belt 106 may have an image defect due to a change in its resistance value or deterioration of surface properties due to deterioration of durability or the like. Therefore, the intermediate transfer belt needs to be replaced with a new one in order to maintain a desired image quality when a predetermined life is reached. The predetermined life is a predetermined counter number by a sheet passing number counter or the like, for example, about 300,000 sheets. In that case, the intermediate transfer body unit 1 is pulled out from the image forming apparatus main body, and only the intermediate transfer body belt 106 is replaced.

  FIG. 5 shows a state where the intermediate transfer body unit 1 is set up. (The self-supporting stand is not shown) The intermediate transfer body unit 1 is detached from the image forming apparatus and can stand alone, and the intermediate transfer body belt 106 is inserted and removed in the direction 63 (vertical direction) in the figure. Exchange old and new. At this time, as described above, the tension of the intermediate transfer belt 106 is released by swinging the arm 12b supporting the tension roller 12 to loosen the tension, and the old intermediate transfer belt 106 is pulled upward by the reference numeral 63. . When the new intermediate transfer belt 106 is inserted, the above-described belt abutting portions 53, 54, and 55 sufficiently protrude, so that the intermediate transfer belt 106 is abutted and inserted toward the protruding portion. Can be easily set in the correct position. Further, it is fixed to the frame 10 with high accuracy independently of the belt position detection sensor 50, and even if it is set to abut against the abutting portion, the position accuracy may be distorted without interfering with the belt position detection sensor 50. Absent. In particular, the intermediate transfer unit is described as being upright, but the intermediate transfer unit is not limited to being upright as long as the posture of the unit can be maintained even in a horizontal direction or an oblique direction.

  As shown in FIG. 4, the abutting portions 53, 54, and 55 sufficiently overlap even when the tension of the intermediate transfer belt 106 is loose. Further, since the abutting portions protrude upward and downward with respect to the tension roller 12 and the driving roller 11, the intermediate transfer belt 106 is not twisted and set. In addition, since the abutting portions are arranged at an optimum pitch, the tension is not tensioned with the abutting failure. If tension is applied with a bad abutment, the belt is kinked, and if the kinked belt is driven, the belt moves in the thrust direction, causing image defects such as image misalignment and color misalignment in the main scanning direction. .

  A one-dot broken line 61 in FIG. 5 indicates an abutting portion of the intermediate transfer belt 106.

  Reference numerals 60 and 62 denote belt steering possible regions. If the belt end portion is deviated from the reference numerals 60 and 62, correct steering is impossible, and the intermediate transfer belt 106 is eventually moved to one side and is damaged. Moreover, if it deviates from a detection area, a correct output cannot be obtained for steering, and there is a problem that control is diverged. Therefore, in this configuration, when a new intermediate transfer belt 106 is set, it is correctly set from the beginning to the contact position 61, so that there is an effect of shortening the center movement control time of the intermediate transfer belt 106 to be initialized. The center movement control is a movement control for forcibly moving the belt to substantially the center 61 in the belt steering possible region (between 60 and 62) so as not to immediately approach the side.

  When the correct belt abutting set is completed and the belt tension is applied, as described above, the belt abutting portion is housed in the intermediate transfer body unit 1 in an interlocked manner. Never become.

  The present invention has been described by taking the intermediate transfer belt as an example. However, the present invention is not limited to this, and for example, a photosensitive belt having a photosensitive layer, a conveyance belt for conveying a sheet, and a toner image transferred to the sheet. It may be a fixing belt for fixing and conveying the toner, and can be applied to an endless belt shape.

DESCRIPTION OF SYMBOLS 1 Intermediate transfer body unit 10 Support frame 11 Drive roller 12 Tension roller 13 Secondary transfer inner roller 50 Belt position detection sensor 51 Eccentric cam 52 Slider 53, 54, 55 Abutting member 101 Photosensitive drum 106 Intermediate transfer body belt 109 2 Next transfer outer roller

Claims (6)

An image forming apparatus comprising: an endless belt; a driving roller that drives the endless belt; and a tension roller that applies tension to the endless belt. The tension roller includes a plurality of abutting members that abut against the endless belt. A tension mechanism movable to a first position where tension is applied to the endless belt and a second position where the endless belt can be inserted and removed;
The abutting member can freely move in and out in conjunction with the tension mechanism of the tension roller. In the first position, the abutting member retreats to the abutting position, and in the second position, the abutting member projects from the abutting position. An image forming apparatus. The image forming apparatus according to claim 1, further comprising a detecting unit that detects a position of an end portion of the endless belt, wherein the abutting position of the abutting unit is arranged at a center of a detection area of the detecting unit. 3. The image forming apparatus according to claim 1, wherein the plurality of abutting portions protrude on a tension side and a loose side of the endless belt suspended from the driving roller and the tension roller. The image forming apparatus according to claim 1, wherein when the tension of the tension roller is loosened, the abutting portions overlap the endless belt. The image forming apparatus according to claim 1, wherein the endless belt can be inserted and removed when the tension of the tension roller is loosened. The image forming apparatus according to claim 1, wherein the endless belt is a transfer belt for transferring an image onto a transfer sheet.