JPH0836314A - Transferring device - Google Patents

Abstract

PURPOSE:To provide a transferring device provided with a simple mechanism for positioning a transferring belt on a photoreceptor. CONSTITUTION:This transferring device is provided with a belt unit 10 constituted of an endless belt 5 which is brought into contact with an image carrier 1 and to which an image on the image carrier 1 is transferred and a supporting means supporting the endless belt 5; a holding unit 30 turnably provided, movably housing the unit 10, and pressing the unit 10 on an image carrier 1 side through a pressing means; and a set means 35 turning the unit 30 so that S the unit 30 approaches and separates with respect to the image carrier 1. is provided with a transferring paper guiding means set at the inclined angle of 20 deg. to 70 deg. with respect to the normal line of the image carrier 1 in a state where the unit 30 is closely arranged to the image carrier 1 on the end of the unit 30 on an upstream side in the transferring paper carrying direction. Only the projecting part of a belt unit supporting means is made to abut on an abutting part on the image carrier 1 side, and the transferring device 4 is positioned on the image carrier 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device which can be applied to an image forming apparatus such as a copying machine, a facsimile or a printer which employs an electrostatic transfer system.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile machine or a printer, an endless transfer belt which contacts an image carrier with a predetermined width is used, and a toner image formed on the image carrier at the contact portion. There is known a transfer device that electrostatically transfers a sheet onto a transfer sheet that is adsorbed and conveyed on a belt. For example, it is as described in JP-A-63-85666.

FIG. 3 illustrates a conventional transfer device using an endless transfer belt in more detail. A transfer belt 51, which is in contact with a photoconductor drum (image carrier) (not shown) with a predetermined width, sucks and conveys the transfer paper, and electrostatically transfers the toner on the photoconductor drum to the transfer paper, is a driving roller 52 and a driven roller. A transfer bias roller (not shown) that is supported by an appropriate tension by 53 and contacts the back surface of the transfer belt 51 to apply a transfer bias to the transfer belt, and a toner that also contacts the surface of the transfer belt 51 and adheres to the transfer belt surface. A cleaning blade for scraping off is arranged.

The transfer device 100 comprises a belt unit 50 and a holding unit 40. Belt unit 5
The protrusions 69 on both ends of the drive roller 52 of
By fitting the bearing portion 68 of the frame 56 of 0,
The belt unit 50 is rotatably attached to the holding unit 40. The holding unit 40 is rotatably attached to the apparatus main body around a fulcrum 70 (two positions in the front and rear).

Below the holding unit 40, a setting means 64 for setting / releasing the holding unit 40 with respect to the photosensitive drum is supported rotatably on the apparatus main body side before and after the holding unit 40. A roller 59 that is provided so as to be connected by a shaft 66 and that abuts against the holding unit 40 by the compression spring 67 in a state where the pressing force is appropriately adjusted is attached.

The holding unit 40 includes a belt unit 5
A pressure lever 60 for pressing 0 is provided, and a coil spring 62 having one end fixed to the frame 56 side is attached to the rear end of the pressure lever 60.
The zero tip portion 63 is arranged so as to contact the belt unit 50 by the tensile force of the coil spring 62.
The pressure lever 60 and the coil spring 62 constitute a biasing means. Further, the holding unit 40 is provided with a transfer paper guide member 58 that receives the transfer paper conveyed from the paper supply unit and guides the transfer paper to the transfer position. The transfer paper guide member 58 guides the non-transfer surface side of the transfer paper, and is integrated with the frame 56 in order to easily and reliably secure the carry-in position accuracy when the transfer paper is carried into the transfer belt 51 as described later. It is configured to

The transfer belt 51 is supported by side plates 54 provided in front of and behind the transfer belt 51. The side plate 54 supports the photoconductor drum and abuts on a face plate which positions the photoconductor drum in the main body of the apparatus. The protrusion 55 is formed,
The belt unit 50 is pressed toward the photoconductor drum by the biasing means, and the protrusion 55 hits the face plate, whereby the belt unit 50 is accurately positioned with respect to the photoconductor drum. By this positioning, the contact width between the photosensitive drum and the transfer belt 51, which is one of the important transfer conditions, the transfer position with respect to a predetermined transfer paper entry position on the transfer belt 51, and the like are determined.

Similarly, projections 57 for supporting the photosensitive drum and abutting on a face plate for positioning the photosensitive drum in the main body of the apparatus are formed at the front and rear of the frame 56,
The holding unit 40 is pressed toward the photosensitive drum by the setting means 64, and the protrusion 57 hits the face plate,
Accurate positioning of the holding unit 40 with respect to the photosensitive drum is performed. In other words, the transfer paper guide member 58 is positioned with respect to the photoconductor drum, the transfer belt, and the transfer position. By this positioning, the transfer paper transfer belt, the photoconductor drum, and the transfer paper, which are one of important transfer conditions, are positioned. The approach direction (angle) to the transfer position and the approach position are determined.

[0009]

As described above, the conventional transfer device using the transfer belt is provided with a positioning mechanism for the transfer belt to the photosensitive drum and a transfer paper guide for guiding the transfer paper carried into the transfer belt. Positioning mechanisms of the holding unit provided with the members with respect to the photoconductor drum are indispensable structures, and when the holding unit is pressed against the photoconductor drum by the setting means and set, the pressure applied to the holding unit is appropriately adjusted. In order to make the adjustment, the setting means requires a special force adjusting mechanism such as a spring.

The image forming apparatus itself such as a copying machine, a facsimile and a printer is composed of many parts. However, the positional relationship between each component is also required to have strict accuracy. Therefore, even if the mechanism becomes complicated, conversely, it is desired from the viewpoint of quality and cost to reduce the number of parts as much as possible and also to reduce the positional relationship between parts that require accuracy. The complicated positioning mechanism of the transfer device used is
There was a demand for simplification.

It is a first object of the present invention to solve the above technical problems and to provide a transfer device provided with a simple positioning mechanism for a transfer belt onto a photosensitive drum.

Further, in addition to the first object, the present invention provides
A second object is to provide a transfer device applied to a small and compact image forming apparatus.

[0013]

In order to achieve the above object, the present invention is configured as follows.

A belt unit comprising an endless belt, which is in contact with the image carrier and on which the image on the image carrier is transferred, and a support means for supporting the endless belt, is rotatably provided.
A holding unit that movably accommodates the belt unit and presses the belt unit toward the image carrier through an urging means, and a rotation of the holding unit so as to approach or separate from the image carrier. In a transfer device having a setting unit, the holding unit is arranged at the upstream end of the holding unit in the transfer paper transport direction in the vicinity of the image carrier, and the angle is 20 ° with respect to the normal line of the image carrier. Positioning of the transfer device with respect to the image carrier is provided by providing transfer paper guide means set at an inclination angle of 70 ° to 70 °, and bringing only the protrusion of the belt unit support means into contact with the abutting part on the image carrier side. A transfer device (Claim 1) for performing.

A transfer device provided with fixing means for fixing the positional relationship between the holding unit and the setting means when the holding unit is arranged close to the image carrier by the setting means. Item 2).

[0016]

According to the invention of claim 1, in a state where the holding unit is arranged at the upstream end of the holding unit in the transfer sheet conveying direction, the holding unit is arranged close to the image carrier, and the angle is 20 ° to 70 ° with respect to the normal line of the image carrier. By providing the transfer paper guide means set at an inclination angle of °, the transfer paper guide means for guiding the non-transfer surface side of the transfer paper can be roughly roughly positioned with respect to the photosensitive drum, the transfer belt and the transfer position. And
The image carrier is substantially eliminated only by the positioning mechanism for the photosensitive drum of the holding unit having the transfer paper guiding means and the special pressing force adjusting mechanism of the setting means. The transfer device can be positioned with respect to. That is, the entrance angle of the transfer paper is 20 ° to 70 ° with respect to the normal line of the image carrier.
By setting to °, one of the important transfer conditions is the transfer belt of the transfer paper, the main guide function to the photosensitive drum, and the transfer position of the transfer paper fixedly arranged in the image forming apparatus. The transfer paper guide means for guiding the transfer surface side is provided, and the transfer paper guide function of the transfer paper guide means on the holding unit side serves as an auxiliary role. Of course, even if it is auxiliary, it is indispensable especially when guiding thin paper, curled paper, etc., and it is still necessary to integrally provide it to the holding unit side.

Further, the transfer paper guide means for guiding the transfer surface side of the transfer paper fixedly arranged in the image forming apparatus is arranged so that the transfer paper is conveyed at a steep angle so that the leading end of the transfer paper conveyed from the paper feeding unit is surely hit. Since it enters, the transfer paper conveyed from the paper supply unit is guided to the transfer belt after once abutting the transfer paper guide means fixedly arranged in the image forming apparatus. Therefore, the transfer paper guide means for guiding the transfer surface side of the transfer paper to the transfer belt, the photosensitive drum, and the transfer position of the transfer paper and the entrance position are fixedly arranged in the image forming apparatus. Therefore, it is always maintained in a substantially constant state.

Further, since the transfer sheet conveying path from the sheet feeding section to the transfer section is set to a steep angle, the occupied volume of the transfer sheet conveying path is reduced as compared with the conventional one, and the space in the width direction of the image forming apparatus main body is reduced. Small and compact.

According to the second aspect of the invention, when the holding unit is set by the setting means, the setting means having no special pressing force adjusting mechanism is simply fitted to the fixing means of the holding unit, and the holding unit and the holding unit are connected. The positional relationship with the setting means is fixed.

[0020]

FIG. 1 shows an embodiment of the present invention. The photoconductor drum 1 (which is an image carrier) (provided with general devices necessary for the image forming process such as a charging device, an exposure device, a developing device, and a cleaning device, which are not shown) is contacted with a predetermined width to transfer the transfer paper. The transfer belt 5 that attracts and conveys the toner onto the transfer paper by electrostatically transferring the toner image on the photosensitive drum 1 to the transfer roller 8
A transfer bias roller 16 that is supported by a driven roller 9 with an appropriate tension, contacts the back surface of the transfer belt 5 and applies a transfer bias to the transfer belt, and toner that contacts the surface of the transfer belt 5 and adheres to the transfer belt surface. A cleaning blade 37 for scraping off the cleaning blade is arranged.

The transfer device 4 comprises a belt unit 10 and a holding unit 30. The protrusions (not shown) at both ends of the drive roller 8 of the belt unit 10 are attached to the holding unit 3
The belt unit 10 is rotatably attached to the holding unit 30 by fitting it to a bearing portion (not shown) of the frame 38 of No. 0, and the holding unit 30 is a device with the fulcrum 33 (the rotation shaft of the drive roller 8) as the center. It is rotatably attached to the body.

At the lower part of the holding unit 30, setting means 35 for setting / releasing the holding unit 30 with respect to the photosensitive drum 1 is provided rotatably to the apparatus main body side before and after the holding unit 40. The tip of the rotatable roller 34 is in contact with the bottom of the holding unit 30 and is fitted to the fixing member 11 provided on the bottom of the holding unit 30.
Is attached.

The holding unit 30 includes the belt unit 1
A pressure lever 13 for pressurizing 0 is connected to a driving means (for example, a cam) (not shown) and is vertically movable. The tip portion 15 of the pressure lever 13 is the belt unit 1
It comes into contact with a part of 0 and is constantly urged upward by the coil spring 14.

A transfer paper guide member 12 for guiding the transfer paper to the transfer position is integrally provided at the end of the frame 38 on the upstream side of the holding unit 30 in the transfer paper transport direction, and the transfer device is in the normal position. In the state of being set to, the transfer path is formed together with the transfer sheet guide members 31 and 39 fixedly arranged in the apparatus main body to guide the transfer sheet transferred from the sheet feeding section. At this time, the transfer paper guide member 12 guides the non-transfer surface side of the transfer paper, and the transfer paper guide members 31, 39 guide the transfer surface side of the transfer paper. The transfer paper guide member 12 is integrally provided at the end of the frame 38 by integral molding, adhesion, heat caulking, or the like. The transfer paper guide member 31 is formed of an elastic member such as a metal thin plate or a resin material, and is bent substantially horizontally in the vicinity of the photoconductor drum, and elastically abuts the front end of the transfer paper that comes in at a steep angle. The transfer paper traveling direction is smoothly changed to a substantially horizontal direction.

The transfer belt 5 is supported by side plates 6 provided in front of and behind the transfer belt 5 to form a belt unit 10. The side plate 6 has a protrusion 3 formed under the face plate 2 for positioning and fixing the photosensitive drum 1 in the apparatus main body.
When the belt unit 10 is pressed toward the photoconductor drum 1 side by the pressure lever 13, the protrusion 7 abuts on the photoconductor drum 1 and the belt unit 10 accurately contacts the photoconductor drum 1. Perform positioning. By this positioning, the contact width between the photosensitive drum and the transfer belt, which is one of the important transfer conditions, and the transfer position with respect to a predetermined transfer paper entrance position on the transfer belt are determined.

The frame 38 of the holding unit 30 does not have a protrusion (positioning portion) that comes into contact with the face plate 2, and thus direct positioning with respect to the photosensitive drum 1 is not performed.

The state in which the transfer sheet enters the transfer section will be described with reference to FIG. The transfer sheet guiding means 12 formed integrally with the holding unit 30 is 20 ° to 70 ° with respect to the normal line A passing through the center point of the photosensitive drum 1 in a state where the transfer device 4 is set at a regular position. The inclination angle is set to 70 ° (inclination angle of 70 ° to 20 ° with respect to the horizontal line orthogonal to the normal line A), preferably 30 ° to 70 °. When the transfer paper is conveyed linearly from the paper feed section to the transfer position at the inclination angle, the leading end of the transfer paper first comes into contact with the transfer paper guide members 31, 39, and then mainly the transfer paper guide member 31. Will be guided to the transfer section.

Further, as a feature of the present invention, the setting object of the inclination angle may be a tangent line of the roller contact portion of the transfer paper guide member 39 or the paper feed roller pair 32 arranged immediately before the transfer portion. In both cases, the inclination angle is set to be substantially similar to that of the transfer paper guide means 12, and therefore, the transfer paper guide member 39 or the photosensitive drum 1 at the tangent line of the roller pair 32 roller contact portion arranged immediately before the transfer portion. The inclination angle with respect to the normal line A passing through the center point may be set to 20 ° to 70 °.

The image forming operation in the above configuration will be described. A nip having a width of 4 to 12 mm is formed at the contact portion between the photosensitive drum 1 and the transfer belt 5. When the transfer paper sent from the registration roller 32 enters there, a transfer bias is applied to the transfer bias roller 16 and a charge having a polarity opposite to that of the toner on the photosensitive drum 1 is applied to the transfer belt 5 to perform the transfer operation. Be done. In this embodiment, the toner charged in + is attached to the photosensitive drum 1 whose surface is charged to about −800 V, and the − high voltage is applied to the transfer bias roller 16 to transfer the toner onto the transfer paper. Since the transfer belt has a belt surface electric resistance of 1 × 10 ⁹ to 1 × 10 ¹² Ω and a belt inner side of 1 × 10 ^{7 to} 5 × 10 ⁸ Ω, the transfer belt 5 and the transfer belt The electric charge applied to the paper is removed by the drive roller 8 as it moves downstream in the transfer paper conveyance direction.

Next, the contact / separation operation of the transfer device 4 with respect to the photosensitive drum 1 will be described. During a normal copying operation, the transfer belt 5 is pushed up by the pressure lever 13 by the urging force of the coil spring 14 and is in contact with the photoconductor drum 1, and the protrusion 7 of the side plate 6 is the protrusion 3 of the face plate 2. The belt unit 1 with respect to the photoconductor drum 1
Accurate positioning of 0 is done. During non-copying operation,
The urging force of the coil spring 14 is released by a cam (not shown), and the pressure lever 13 descends. Along with this, the belt unit 10 is lowered by its own weight, and the transfer belt 5 is separated from the photosensitive drum 1. That is, the biasing force of the coil spring 14 can be controlled to be turned on / off, and the transfer belt 5 can be brought into contact with or released from the photosensitive drum 1. As a result, unnecessary frictional deterioration and deterioration with time can be prevented by keeping the transfer belt 5 and the photoconductor 1 separated from each other except when necessary such as during a copying operation.

In addition, the transfer device 4 is required for jam processing and the like.
When it is desired to largely separate the photosensitive drum 1 from the photosensitive drum 1, the lever 35 is manually rotated in the arrow direction to move the setting means 35 in the arrow direction from the position shown in the figure, and the holding unit 30 is centered on the shaft 33. To rotate downward.
When the holding unit 30 is returned to the regular setting position, the lever 35 is manually rotated in the direction opposite to the arrow to move the setting means 35 from the position shown in the figure to the direction opposite to the arrow, and the setting means is moved. A rotatable roller 34 attached to the tip of 35 is fitted to the fixing member 11 provided at the bottom of the holding unit 30. As a result, the holding unit 30 is reliably positioned and fixed in the image forming apparatus. Furthermore, by fixing it, resonance does not occur with respect to vibrations and shocks generated during mechanical transportation, and there is no risk of damage or breakage.

[0032]

As described above, according to the present invention, it is possible to realize a transfer device having a simple positioning mechanism for the transfer belt onto the photosensitive drum. Furthermore, a transfer device applied to a small and compact image forming apparatus can also be realized.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a schematic view showing the same embodiment.

FIG. 3 shows a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 4 Transfer device 5 Transfer belt 10 Belt unit 11 Fixing member 12 Transfer paper guide member 13 Pressure lever 30 Holding unit 31 Transfer paper guide member 35 Setting means 39 Transfer paper guide member

Claims (2)

[Claims] 1. A belt unit comprising an endless belt which comes into contact with an image carrier and onto which an image on the image carrier is transferred, and a support means which supports the endless belt, and the belt unit being rotatably provided. A holding unit that movably accommodates the unit and presses the belt unit toward the image carrier through a biasing unit, and a set that rotates the holding unit so as to approach or separate from the image carrier. In a transfer device having a means, the holding unit is arranged at an upstream end portion of the holding unit in the transfer paper transport direction in the vicinity of the image carrier, and the angle is 20 ° with respect to a normal line of the image carrier.
Positioning of the transfer device with respect to the image carrier is provided by providing transfer paper guide means set at an inclination angle of 70 ° to 70 °, and bringing only the protrusion of the belt unit support means into contact with the abutting portion on the image carrier side. A transfer device characterized by performing. 2. The fixing unit according to claim 1, wherein the holding unit fixes the positional relationship between the holding unit and the setting unit when the holding unit is arranged close to the image carrier by the setting unit. A transfer device characterized by being provided.