JPH10319733A - Transfer device - Google Patents

Abstract

(57) [Problem] To provide a transfer device in which an image transferred on a sheet hardly expands and contracts. A fixing member (14, 7) fixed to an outer periphery of a rotation shaft (1) of a driving roller (27) is supported on the outer periphery of the rotation shaft so as to be rotatable and movable in the axial direction of the rotation shaft. Movable members (13,
17,15,6,16,18,9), the gear part (2) provided on the outer peripheral surface of the movable member, and the movable member pressed against the fixed member to apply a frictional load between the fixed member and the movable member. Pressing member to generate (3)
And

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transfer device for transferring a developed image formed on a photoreceptor onto paper.

[0002]

2. Description of the Related Art As one form of a transfer device for transferring a developed image formed on a photoreceptor onto paper, as shown in FIG.
A transfer belt 29 wrapped around a drive roller 27 and an idler roller 26 and supported endlessly movably, and a transfer bias of a predetermined polarity is applied from the back side of the transfer belt 29 to form a developed image formed on the photoconductor 25. Transfer belt 29
Transfer device 28 for transferring onto paper 40 conveyed by
Is known.

[0003]

By the way, in this type of transfer apparatus, conventionally, as shown in FIG. 2, a motor 23 (see FIG. 5) is required to accurately transmit the rotation of the motor 23 (see FIG. 5) to the driving roller 27. And the rotating shaft 1 of the driving roller 27 are fixed by bonding or press fitting. Ideally, the peripheral speeds of the photoconductor 25 and the transfer belt 29 are the same. However, due to variations in the outer dimensions of the photoconductor 25 and the drive roller 27, variations in the thickness of the transfer belt 29, and the like, When the gear 2 and the rotating shaft 1 are integrally formed as described above, it is difficult to make the peripheral speeds of the photosensitive member 25 and the transfer belt 29 completely the same. When the paper 40 passes between the photoreceptor 25 and the transfer belt 29 in a state where the peripheral speeds do not match, the paper 40
This causes a problem of image disorder such that the image of the developed image (toner image) transferred thereon becomes an image elongated in the paper transport direction, or conversely, becomes a contracted image.

Accordingly, it is an object of the present invention to provide a transfer device in which an image transferred on a sheet is less likely to expand and contract.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer belt which is stretched over a drive roller and an idler roller and is supported so as to be movable endlessly. A transfer device for transferring a developed image formed on a body onto a sheet conveyed by the transfer belt, wherein a fixing member fixed to the outer periphery of the rotation shaft of the drive roller; A movable member rotatably supported movably in the axial direction of the rotating shaft, a gear portion provided on an outer peripheral surface of the movable member, and the movable member being pressed against the fixed member to form the fixed member And a pressing member for generating a frictional load between the movable members.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. Although the configuration of the transfer device partially overlaps the description of the prior art, as shown in FIG. 5, a conductive transfer belt 29 that is supported over a drive roller 27 and an idler roller 26 and supported endlessly. And a transfer bias of a predetermined polarity is applied from the back side of the transfer belt 29 to
And a transfer unit 28 for transferring the developed image formed thereon onto a sheet 40 conveyed by a transfer belt 29. The photoreceptor 25 rotates by receiving power from a motor 24,
The transfer belt 29 moves endlessly as the drive roller 27 rotates receiving the power from the motor 23. Photoconductor 2
5 and the transfer belt 29 rotate so as to feed the paper 40 in the same direction.
3, 24 are respectively rotated. The paper 40 to which the developed image has been transferred is nipped and conveyed while being heated and pressed by a fixing roller, and the developed image is fixed on the paper 40.

Next, the driving roller 2 which is a feature of the present invention is described.
The configuration between the rotating shaft 1 and the gear 2 of the first embodiment will be described. FIG. 1 is a sectional view of a main part showing a first embodiment. In FIG.
The rotating shaft 1 of the driving roller 27 is supported by a bearing 4 on a frame of a transfer device (not shown). The outer ring 15 of the ball bearing 10 is fixed to the gear 2 by bonding or press fitting, and the inner ring 14 of the ball bearing 11 is fixed to the rotating shaft 1 of the driving roller 27 by bonding or press fitting.
A spacer 6 that supports only the outer ring 15 and the outer ring 16 is provided between the ball bearing 10 and the ball bearing 11. A gap is formed between the inner ring 13 of the ball bearing 10 and the outer periphery of the rotating shaft 1. The retaining ring 5 is provided on the rotating shaft 1 so that the inner ring 13 of the ball bearing 10 is pressed with a certain load, and the spring 3 is arranged.

The spring 3 is an inner ring 13 of the ball bearing 10.
, The inner ring 13 presses the ball 17, the ball 17 presses the outer ring 15, and the outer ring 15
, The outer ring 16 pushes the ball 18 and the ball 1
8 pushes the inner ring 14. Thus, since the inner ring 14 is fixed to the rotating shaft 1, a friction load is generated between the inner ring, the ball, and the outer ring.

As shown in FIG. 4, the transfer belt 29 is pressed against the photosensitive member 25 by the position of the support shaft 31 with a load N due to the belt tension. The friction force is μ
Then, the frictional force F becomes F = μN. Further, an attractive force G due to static electricity acts between the transfer belt 29 and the photoconductor 25. If the sum of the frictional force F and the electrostatic attraction G is larger than the load T on the transfer belt, that is, T <(F +
In the case of G), the transfer belt 29 rotates with the photoconductor 25. Therefore, the load of the spring 3 is set to a load that results in the value of T.

FIG. 4 is a sectional view showing a main part of another embodiment of the present invention shown in FIG. 3, and a sliding member 8 is used in place of the ball bearing shown in FIG.
Is fixed to the rotating shaft 1 by bonding or press fitting. A sliding member 8 is also provided on a movable member 9 having the gear 2, and a load is applied by the spring 3 as in FIG. 1 so that a frictional load is generated between the sliding members 8.

[0011]

As described above, according to the present invention, an appropriate friction clutch is formed between the gear and the driving roller to perform auxiliary driving, and the photosensitive member, the sheet, and the transfer belt are caused to have an electrostatic action and a friction action. As a result, the peripheral speed between the photosensitive member and the transfer belt can be substantially equalized, so that it is possible to provide a transfer device in which an image transferred on a sheet is less likely to expand and contract.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing a conventional technique.

FIG. 3 is a sectional view of a main part showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a load relationship in the transfer device.

FIG. 5 is a partially cut-away schematic perspective view showing a general configuration of a transfer device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating shaft, 2 ... Gear, 3 ... Spring, 5 ... Retaining ring, 6 ... Spacer, 10, 11 ... Ball bearing, 7
... Stopper, 8 ... Sliding member, 27 ... Drive roller.

Claims (2)

[Claims] A transfer belt having a predetermined polarity applied from a back side of the transfer belt, the transfer belt being supported by a drive roller and an idler roller and supported endlessly, and a developed image formed on a photoreceptor. And a transfer device for transferring the transfer roller onto a sheet conveyed by the transfer belt, wherein a fixing member fixed to the outer periphery of a rotation shaft of the driving roller; A movable member supported movably in the axial direction, a gear portion provided on the outer peripheral surface of the movable member, and a pressure load between the fixed member and the movable member by pressing the movable member against the fixed member. And a pressing member for generating the image. 2. The load exerted on the movable member by the pressing member is:
When the load on the transfer belt is T, the frictional force of the transfer belt is F, and the attraction force due to static electricity between the photosensitive member and the transfer belt is G, the relationship satisfies T <(F + G). The transfer device according to claim 1, wherein