JPS59184379A - Transfer and carrying device - Google Patents

Abstract

PURPOSE:To prevent a position shift and a snake motion even with a thin and wide belt, and to prevent a color blurring by providing a carrying belt, a collar rolller having an extended belt, a tension member for giving tensile strength to the belt, and an auxiliary roller for pressing the belt against the collar roller. CONSTITUTION:The auxiliary roller 4 is cylindrical, its width is a little narrower than an interval of collars 2a, 2b of a driving roller 2, a bearing 12 is fitted into a shaft 11 of the roller 4, the bearing 11 is capable of sliding toward the center of the roller 2 by a guide, and the other end of a tension spring 13 fixing one end is attached to the bearing 11 to press a carrying belt 1 to sandwich between the roller 4 and the roller 2. An auxiliary roller 5 has the same shape as the auxiliary roller 4, and in the same way, the carrying belt 1 is sandwiched between this roller and a roller 3. The belt 1 is obstructed for its movement in the width direction by the collars 2a, 2b provided on the end part of the roller 2, and also even if a crease and twist are generated in the belt 1, it is pressed to prevent a displacement in the thickness direction. The relation of the driven roller 3 and the auxiliary roller 5 is also the same.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer conveyance device for conveying a transfer material used in an electrophotographic copying apparatus or the like.

In electrophotographic copying machines and the like, in order to transfer the toner image developed and visualized in the developing section onto the transfer material, a conveyance device is used to convey the transfer material to the transfer position. The format is used. Among these, a device in which a transfer material is supported by electrostatic attraction on an endless belt made of an insulator and transported to a transfer position is also one of this type of device. Due to the manufacturing process, it is very difficult to match the circumferential length of belts such as those shown in L on both sides in the belt width direction, resulting in a difference in circumferential length. The length difference gradually accumulates. The force generated by this acts in the lateral direction of the belt movement direction.

There is also a risk that the belt may wrinkle or twist, or the belt may move laterally and fall off the rollers. Further, the transfer material P is sent out from the registration roller lO and conveyed by the conveyor belt l.
The preliminary charging device H9 from below (Fig. 1) attracts and supports one conveyor belt 1 due to electrostatic action due to corona discharge, but if the conveyor belt 1 has wrinkles or kinks, the entire surface of the transfer material P cannot be tightly attached. A part of it will be floating. Therefore, the suction force becomes weak and the transfer material P may be skewed during conveyance. In addition, if there is a floating part between the transfer material P and the conveyor belt 1 at the transfer position, the transfer efficiency will be extremely poor in that part and cause uneven transfer, so prevent the conveyor belt from wrinkling. There is a need to. To prevent this, there are methods that use so-called drum rollers with a bulge in the center as the driving roller 2 and driven roller 3, and methods that use rollers with flanges that have flanges on both ends of the rollers. There are drawbacks such as.

When a drum roller is used, the conveyor belt 1 has a medium height relative to the image carrier 7 according to the shape of the drum roller, and the transfer material that is attracted to the conveyor belt 1 and is conveyed also has a medium height. The transfer material transported to the transfer position is subjected to corona discharge by the transfer charging device, but since the distance between the transfer material and the charging wire is uneven due to the medium height, the electrostatic effect does not work uniformly over the entire surface, and therefore This causes uneven transfer.

Also, in terms of middle and high drum rollers, the moving speed at the center of the conveyor belt 1 is faster than at both ends, and since the conveyor belt 1 is conveyed while receiving forces from both ends toward the center, the forces are balanced. Although it is relatively stable, the balance state is lost due to uneven friction coefficient and vibration on the back surface of the conveyor belt (1), causing the conveyor belt (1) to meander and cause misalignment. Particularly in a color copying apparatus that performs multi-color multiple transfer, color misregistration becomes noticeable.

In addition, in the case of a model that uses a flange roller, the belt width is narrow and is effective for belts with strong elasticity, but the conveyor belts used in transfer devices that use belt conveyance are generally thin, wide, and have weak elasticity, and the belt width is narrow and the elasticity is weak. It is difficult to prevent wrinkles and kinks caused by the difference in circumferential length, and the belt can only be prevented from falling off by the collar.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer and conveyance device which eliminates the drawbacks listed in item L and allows even a thin and wide belt to be used satisfactorily.

The present invention relates to a transfer type image forming apparatus that transfers a toner image developed on a photoreceptor to a transfer material, and includes a belt for conveying the transfer material to a transfer position of an image carrier, and a flange roller over which the belt is passed. It consists of a tensioning member that applies tension to the belt and an auxiliary roller that presses the belt against the flanged roller.

Hereinafter, embodiments of the present invention will be described based on the drawings. 1st
The figure is a side view showing an embodiment of the present invention, and FIG. 2 is an IE side view showing a driving roller and an auxiliary roller. The drive roller 2 has a collar 2a, 2a', 2b on both end surfaces thereof.

The interval between the conveyor belts 2b and 2b corresponds to the width of the conveyor belt 1, and the distance between the driving rollers 2
The radius difference between the flange 2a' and the flange 2b is at least the conveyor belt 1.
The thickness is greater than or equal to the thickness of The driven roller 3 has the same shape as the drive roller 2, and is rotatably disposed on a side plate of the conveying device (not shown). An endless conveyor belt 1 made of an insulator is passed around a driving roller 2 and a driven roller 3, and is subjected to tension by a tension roller 6 as a belt tensioning member. Therefore, the conveyor belt 1 is flattened, and the distance between the image carrier 7 and the charging wire of the transfer device 8 is kept uniform.

In this state, the auxiliary rollers 4 and 5 are pressed and installed at a position where the conveyor belt 1 contacts the drive roller 2 and the driven roller 3. As shown in FIG. 2, the auxiliary roller 4 is a cylindrical roller, and the roller width is equal to the collar 2a of the drive roller 2,
2b, and a bearing 12 is fitted into the shaft 11 of the auxiliary roller 4, and the bearing 11 can be slid toward the center of the drive roller 2 using a kite (not shown).
- The other end of the tension spring 13 whose end is fixed is attached to the bearing 11 to press the conveyor belt 1 sandwiched between the auxiliary roller 4 and the drive roller 2. The auxiliary roller 5 has the same shape as the auxiliary roller 4, and similarly pinches the conveyor belt 1 between it and the driven roller 3.

When the drive roller 2 rotates, the conveyor belt 1 runs in the direction of the arrow shown in FIG. Even if wrinkles or kinks occur in 1, they will be pressed and displacement in the thickness direction will be prevented. The relationship between the driven roller 3 and the auxiliary roller 5 is also similar.

As explained above, in the device of the present invention, the width direction is restricted by the collar and is pressed by the auxiliary roller, so it is possible to prevent positional scratches, meandering, and falling off of the conveyor belt in the width direction, and belt tension. After the belt is flattened by applying tension to the conveyor belt, the auxiliary roller is pressed, so that displacement in the thickness direction is stopped, wrinkles and kinks are prevented, and the flatness of the conveyor belt is maintained. Therefore, at the transfer position, the distance between the transfer material supported by the conveyor belt and the charging wire is maintained uniform, which prevents uneven transfer. Also, the conveyor belt is prevented from shifting and meandering, which prevents color misregistration. It can be prevented. This is particularly effective for color copying bags that perform multi-color multi-transfer.

Furthermore, since the flange roller and the auxiliary roller prevent displacement of the conveyor belt in the width direction and thickness direction, it is possible to use thin, wide, and weak belts.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the present invention, and FIG. 21 is a front view showing a driving roller and an auxiliary roller. DESCRIPTION OF SYMBOLS 1... Conveyance belt 2... Drive roller 3... Driven 1: I-ra 4, 5... Auxiliary roller, 6... Tension roller. Patent Applicant Canon Co., Ltd. Agent Arai-be

Claims (1)

[Claims] (In a transfer type image forming device that transfers a toner image formed on a carrier onto a transfer material, a belt that conveys the transfer material to the transfer position of the image carrier and a flange on which the belt is passed) A transfer conveyance device comprising a roller, a belt tensioning member that applies tension to the belt, and an auxiliary roller that presses the belt against the horn <4=f roller.