JP2010256809A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately position the relative position of a transfer roller and a backup roller and the relative position of a conveying unit and the backup roller. <P>SOLUTION: An image forming apparatus includes an image carrier 8 for carrying toner images; the transfer roller 12 for sandwiching a material to be transferred to be pressed against the image carrier; the backup roller 10 for receiving pressing reaction of the transfer roller pressed against the image carrier; and a positioning mechanism 41 for positioning the relative position of the transfer roller and the backup roller. The image forming apparatus incorporates a transfer roller support member 36, rotatably supporting the transfer roller in the conveying unit 25 attached to the backup roller. The transfer roller support member is incorporated in the conveying unit via an accommodation part 39 that allows movement in a direction of intersecting the pressing direction with respect to the image carrier of the transfer roller. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image carrier that carries a toner image, a transfer roller that is pressed against the image carrier with a transfer material interposed therebetween, and a backup roller that receives a pressing reaction force of the transfer roller pressed against the image carrier. And a transfer roller support member that rotatably supports the transfer roller is incorporated in a transport unit that is assembled to the backup roller. The present invention relates to an image forming apparatus.

In the image forming apparatus, conventionally, a transfer roller support member that rotatably supports the transfer roller is assembled so as to be swingable around a fixed axis with respect to the intermediate transfer belt (see, for example, Patent Document 1). ).
As the positioning mechanism, for example, a mechanism capable of positioning the relative position by engaging the rotation shaft of the backup roller with a U-shaped notch formed in the transfer roller support member is provided.

JP-A-11-52747

In the above-described conventional image forming apparatus, the transfer roller support member is assembled so as to be swingable around a fixed axis with respect to the transport unit, so that there is a variation in the dimensions of the transport unit itself or its component parts. If the relative position between the transfer roller and the backup roller is positioned, the relative position between the transport unit and the backup roller may be shifted even if the transport unit is assembled at an appropriate relative position with respect to the backup roller. There is.
For this reason, in cooperation with the sheet conveying member assembled at a predetermined position with respect to the backup roller and the sheet conveying member assembled in the conveying unit, the sheet is conveyed toward the transfer roller, or the sheet that has passed the transfer roller is removed. If the relative position between the transport unit and the backup roller is shifted when the transport unit is configured to be transported, the relative position between the paper transport members will be crumpled and the paper cannot be transported normally. There is.
The present invention has been made in view of the above circumstances, and an object of the present invention is to enable accurate positioning of the relative position between the transfer roller and the backup roller and the relative position between the transport unit and the backup roller.

  A first characteristic configuration of the present invention includes an image carrier that carries a toner image, a transfer roller that is pressed against the image carrier with a transfer material interposed therebetween, and a pressing reaction of the transfer roller that is pressed against the image carrier. A transfer roller support member that has a backup roller that receives force and a positioning mechanism that positions a relative position between the transfer roller and the backup roller, and that rotatably supports the transfer roller is assembled to the backup roller. In the image forming apparatus incorporated in the transport unit, the transfer roller support member is moved through the interchangeable portion that allows the transfer roller to move in a direction crossing the pressing direction of the image carrier. It is built in the transport unit.

In the case of the image forming apparatus of this configuration, when the relative position between the transfer roller and the backup roller is positioned, the transfer roller support member moves in a direction crossing the pressing direction of the transfer roller against the image carrier with respect to the transport unit. Therefore, the relative position between the transport unit and the backup roller is less likely to be shifted.
Therefore, the relative position between the transfer roller and the backup roller and the relative position between the transport unit and the backup roller can be easily positioned with high accuracy.

  According to a second characteristic configuration of the present invention, the positioning mechanism is formed in a recess formed in one of the backup roller support member and the transfer roller support member that rotatably supports the backup roller. A guide is configured to be able to be positioned by engaging a convex portion from a direction along the pressing direction, and guides the concave portion or the convex portion so that the engagement posture of the convex portion and the concave portion becomes a predetermined posture. Is in the point provided.

  With this configuration, when positioning the relative position between the transfer roller and the backup roller, the convex portion and the concave portion can be easily engaged in a predetermined posture, and the relative position between the transfer roller and the backup roller can be positioned with higher accuracy. easy.

Side view showing inside of image forming apparatus Side view of the main part Perspective view of main parts Side view of the main part

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a four-color full-color printer employing an intermediate transfer method and a tandem method as an example of an electrophotographic image forming apparatus according to the present invention.

  The image forming apparatus is provided with a cassette type paper feeding unit 1, a manual paper feeding unit 2, a paper transport unit 3, an image forming unit 4, a paper discharge unit 5, and the like. The paper transport unit 3 is provided between the apparatus main body 6 and the front cover 7.

The image forming unit 4 is provided with an endless intermediate transfer belt 8 as an image carrier that carries a toner image, and four image forming units 9 arranged along the intermediate transfer belt 8.
The image forming unit 9 is provided for each color of magenta (M), cyan (C), yellow (Y), and black (K).

The intermediate transfer belt 8 is wound around the drive roller 10 and the driven roller 11 and rotates in the direction of arrow A in the drawing.
The driving roller 10 is opposed to the secondary transfer roller 12 and functions as a backup roller that receives the pressing reaction force of the secondary transfer roller 12 pressed against the intermediate transfer belt 8.

  The driving roller 10, the driven roller 11, the intermediate transfer belt 8, the primary transfer roller 13, and the like are integrally incorporated in the transfer frame 14 and constitute an intermediate transfer unit 15 as a whole.

  Each of the image forming units 9 includes a photosensitive drum 16 and a charging device 17, an exposure device 18, a developing device 19, a drum cleaner 20, and the like that are disposed around the photosensitive drum 16.

The primary transfer roller 13 primarily transfers the toner image formed on the surface of the photosensitive drum 16 to the intermediate transfer belt 8.
The toner images of each color formed for each image forming unit 9 are sequentially transferred to the intermediate transfer belt 8 by the primary transfer roller 13 and superimposed.
The full-color toner image transferred to the intermediate transfer belt 8 is secondarily transferred to a sheet (transfer material) P by the secondary transfer roller 12.

  The paper transport unit 3 includes a paper transport path 21 that transports the paper fed from the cassette-type paper feed unit 1 or the manual paper feed unit 2 toward the paper discharge unit 5 and one side for duplex printing. And a reverse conveyance path 22 that reverses the paper P after the toner image is fixed on the front and back and sends the paper P to the paper conveyance path 21 again.

  The sheet conveyance path 21 is provided between a rear guide 23 provided on the opposite side of the apparatus body 6 and a front guide 24 on the front cover 7 side, and a part of the front guide 24 is conveyed. The unit 25 is provided.

  In the paper transport path 21, a pickup roller 26, a paper feed roller pair 27, a transport roller pair 28, a registration roller pair 29, a secondary transfer roller 12 pressed against the intermediate transfer belt 8 with the paper P interposed therebetween, and a fixing roller pair 30. A paper discharge roller pair 31 and the like are provided.

  The full color toner image transferred to the intermediate transfer belt 8 is secondarily transferred by the secondary transfer roller 12 to the paper P sent to the paper transport path 21, and the transferred toner image is heated by the fixing roller pair 30. -Pressurized and fixed on paper P.

The transport unit 25 is disposed between the paper transport path 21 and the reverse transport path 22.
The transport unit 25 includes a part of the front guide 24 in the paper transport path 21, a part of the rear guide 32 in the reverse transport path 22, an idle roller 29 a of the registration roller pair 29, and a secondary transfer roller. 12 and one roller 33 a of the reverse conveyance roller pair 33 are incorporated across the left and right side plates 34.

As shown in FIGS. 2A and 2B, the transport unit 25 has a swing axis X at the lower part of the left and right side plates 34, and can swing up and down (openable and closable) on the apparatus body 6 side. ) Is supported.
As shown in FIGS. 2A and 2B, the front cover 7 has a swing shaft 35 on the lower end side, and is supported on the apparatus body 6 side so as to be swingable up and down (openable and closable). Yes.
The transport unit 25 is opened and closed in conjunction with the opening and closing operation of the front cover 7.

  When the front cover 7 is moved to the closed position as shown in FIG. 2A, the transport unit 25 is brought into contact with the rollers of the registration roller pair 29, and the secondary transfer roller 12 causes the intermediate transfer belt 8 to move. Move to the closing position where you are pressing.

  When the front cover 7 is moved to the open position as shown in FIG. 2B when a paper jam or the like occurs, the transport unit 25 causes the rollers of the registration roller pair 29 to be separated from each other and the secondary transfer. The roller 12 moves to an open position away from the intermediate transfer belt 8.

That is, the transport unit 25 is assembled to the drive roller 10 by moving from the open position to the closed position.
As shown in FIG. 3, a transfer roller support member 36 that rotatably supports the secondary transfer roller 12 is incorporated in the transport unit 25.

  The transfer roller support member 36 is formed in a rectangular frame shape having support portions 37 that rotatably support both ends of the secondary transfer roller 12, and the secondary transfer roller 12 extends across the left and right side plates 34. It is supported so as to be able to swing left and right around a swing shaft 38 fixed in parallel with the rotation axis.

  The transfer roller support member 36 is biased by a coil spring 45 so as to swing toward the apparatus main body 6, and the secondary transfer roller 12 presses the intermediate transfer belt 8 by the biasing force of the coil spring 45. .

  As shown in FIG. 4, the transfer roller support member 36 is a flexible portion that allows the secondary transfer roller 12 to move in a direction intersecting the pressing direction of the intermediate transfer belt 8 with respect to the intermediate transfer belt 8 (a direction substantially orthogonal in the present embodiment). 39, and is swingably supported around the swing shaft 38.

  The interchangeable portion 39 is long along the line segment L passing through the rotation axis Y of the secondary transfer roller 12, and the width in the direction perpendicular to the line segment L is a width that allows the swing shaft 38 to be inserted. A long hole 40 is formed in the transfer roller support member 36, and a swing shaft 38 is inserted into the long hole 40.

  As shown in FIG. 4, the secondary transfer roller 12 and the drive roller 10 extend over a transfer frame 14 as a backup roller support member that rotatably supports the drive roller (backup roller) 10 and the transfer roller support member 36. Is provided with a positioning mechanism 41 for positioning the relative position between the two.

  The positioning mechanism 41 can be positioned by engaging the convex portion 43 formed on the transfer roller support member 36 with the concave portion 42 formed on the transfer frame 14 from the pressing direction of the secondary transfer roller 12 with respect to the intermediate transfer belt 8. It is configured.

  Although not shown, the recess 42 may be formed on the transfer roller support member 36 and the protrusion 43 may be formed on the transfer frame 14.

The concave portion 42 is formed in a shape that becomes narrower toward the bottom surface side, and a guide 44 is provided to guide the engagement posture between the convex portion 43 and the concave portion 42 to a predetermined posture.
Although not shown, the convex portion 43 may be formed in a shape that becomes narrower toward the tip side, and a guide 44 that guides the engagement posture between the convex portion 43 and the concave portion 42 to a predetermined posture may be provided. Good.

[Other Embodiments]
1. The image forming apparatus according to the present invention is a photoconductor layer in which an image carrier is laminated on a drum body of a photoconductor drum, and a transfer roller that is pressed against the image carrier (photoconductor layer) with a transfer material interposed therebetween. The backup roller that is the primary transfer roller and receives the pressing reaction force of the transfer roller (primary transfer roller) pressed against the image carrier (photosensitive layer) may be the drum body of the photosensitive drum.
2. The image forming apparatus according to the present invention may be a printer, a copier, a facsimile, or a complex machine of these.

8 Image carrier 10 Backup roller 12 Transfer roller 14 Backup roller support member 25 Conveying unit 36 Transfer roller support member 39 Fusing portion 41 Positioning mechanism 42 Concave portion 43 Convex portion 44 Guide P Transfer material

Claims (2)

An image carrier that carries a toner image; a transfer roller that is pressed against the image carrier across a transfer material; a backup roller that receives a pressing reaction force of the transfer roller pressed against the image carrier; and the transfer A positioning mechanism for positioning a relative position between the roller and the backup roller;
An image forming apparatus in which a transfer roller support member that rotatably supports the transfer roller is incorporated in a transport unit that is assembled to the backup roller,
The image forming apparatus in which the transfer roller support member is incorporated in the transport unit via an interchangeable portion that allows movement of the transfer roller in a direction crossing a pressing direction of the transfer roller with respect to the image carrier. The positioning mechanism has a recess formed in one of the backup roller support member and the transfer roller support member that rotatably supports the backup roller, and a convex portion formed in the other along the pressing direction. It is configured to be able to position by engaging from
The image forming apparatus according to claim 1, wherein a guide for guiding the engagement posture between the convex portion and the concave portion to a predetermined posture is provided in the concave portion or the convex portion.

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