JPH01235979A - Image forming device - Google Patents

Abstract

PURPOSE:To surely transmit driving power to a carrying belt and to stabilize the driving of the carrying belt by providing a turning press-contact member which brings the carrying belt into pressurized contact with a driving roller and pinches the belt to the above device. CONSTITUTION:A roller 14 as the turning press-contact member is juxtaposed with the driving roller 10. The roller 14 is turnably mounted to an arm 15 and the arm 15 is turnably provided to a stationary shaft 16. The roller 14 turns around the shaft 16 when the arm 15 is pressed by the energizing force of a spring 17. The roller is thereby brought into pressurized contact with the transfer belt 9 wound around the driving roller 10. The part held in pressurized contact with the turning press-contact member 14 can be held under the surface pressure higher than the surface pressure on the other part of the carrying belt. The driving power from the driving roller is thereby sufficiently transmitted to the carrying belt and the carrying capacity stable over a long period of time is obtd.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention obtains an image by transferring an image formed at an image forming station onto a transfer material conveyed to the image forming station by a conveying means. The present invention relates to an image forming apparatus, and particularly to an image forming apparatus equipped with a belt conveyance mechanism for transfer material.

(Prior Art) Conventionally, an image forming apparatus using an electrophotographic process includes an image forming station that forms a latent image using light, magnetism, electric charge, etc., and visualizes the latent image to obtain a visible image; The image forming apparatus includes a conveying means for conveying a transfer material to the image forming station in order to transfer the image on the image forming station, and a fixing means for fixing the image transferred onto the transfer material onto the transfer material. There is.

The image forming station has, for example, an electrophotographic photoreceptor or other image forming medium having various characteristics and shapes, and is further provided with various latent image forming means, developing means, etc. corresponding to the image forming medium. configured.

Conveying means can be roughly divided into those consisting of a pair of rollers that convey the transfer material by sandwiching it in a transfer material conveyance path, and those in which the transfer material is placed on a belt-shaped conveyance material. However, there is a configuration in which the transfer material is transported from the transfer material supply port to the entrance of the fixing device.

If a roller configuration consisting of a plurality of roller pairs is used as a conveying means, the leading edge of the transfer material is pinched by the rollers many times, resulting in damage to the leading edge of the transfer material.
For this reason, it cannot be said that it is an excellent conveyance means in terms of high conveyance speed and conveyance stability depending on the type of transfer material. Furthermore, since the length of the transfer material that can be conveyed is determined by the distance between each roller, there are restrictions on the size of the transfer material to be used.

On the other hand, in a conveyance means configured to use a belt-like conveyance material (conveyance bell l-) to convey the transfer material to the transfer position of the image forming medium and further to the fixing means, the transfer material enters the supply input lobby fixing device. Since the transfer material is conveyed while being placed on the conveyor belt, it has the advantage that conveyance defects are extremely rare compared to roller configurations in which the transfer material is conveyed by roller rotation. In addition, in the roller-structured conveyance means, there are many places where various members in the image forming apparatus and the transfer material come into sliding contact, and the transfer material may become electrically charged due to friction, and if the transfer material is paper, it may generate paper dust. However, conveyance means using conveyor belts do not have such problems.

(Problems to be Solved by the Invention) However, in such conventional examples, although the conveyance means consisting of a conveyor belt has many advantages, when transferring an image from an image forming station onto a transfer material, Since a conveyor belt is interposed between the transfer material and a transfer charger that generates the charge required to transfer the image, there is a problem that transfer efficiency is reduced.

In order to improve the transfer efficiency, it is necessary to create a thin belt of approximately several hundred microns using a resin material that has relatively low volume resistance and high mechanical strength. Conveyor belts made of resin materials that satisfy the above characteristics will have lower rubber elasticity as the strength, or tensile modulus, is increased, so if strong tension is applied when stretching the conveyor belt using multiple rollers, However, it has the problem of causing creep strain and deformation. Therefore, the contact surface pressure between the drive roller that drives the conveyance belt and the surface of the transfer belt is generally set low.

By the way, if the contact surface pressure between the conveyor belt and the drive roller is low, the anchoring effect between the conveyor belt and the drive roller will not appear.
Since the driving force is not completely transmitted from the drive roller to the conveyor belt, the drive of the conveyor belt becomes unstable. There is a problem in that this unstable running of the conveyor belt significantly reduces the quality of recorded images.

Furthermore, in image forming apparatuses that use toner, which is fine resin powder, the scattered toner adheres to the surface of the drive roller, extremely reducing the coefficient of friction on the surface of the drive roller, which gradually reduces the drive of the conveyor belt. There is a problem in that the performance is lost, and in the worst case, at t4, the conveyor belt cannot be driven due to slipping of the drive roller.

Therefore, the present invention has been made to solve the above-mentioned problems of the conventional example, and its purpose is to increase the contact surface pressure between the conveyor belt and the drive roller surface at the pressure contact portion of the rotary pressure contact member, An object of the present invention is to provide an image forming apparatus in which driving force of the conveyor belt is completely transmitted from a drive roller to the conveyor belt, thereby stabilizing the drive of the conveyor belt.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, an image formed at an image forming station is transferred to a transfer material by a conveyor belt to the image forming station. In an image forming apparatus that forms an image by transferring an image to a surface, the image forming apparatus includes a drive roller for driving the conveyor belt, and a rotary pressing member that is arranged in parallel with the drive roller and that presses and clamps the conveyor belt against the drive roller. It is constructed by having the following.

(Function) In the present invention having the above-mentioned configuration, the rotary press member presses and holds the conveyor belt on the drive roller for driving the conveyor belt, so that the pressure contact portion of the rotary press member The contact pressure between the conveyor roller and drive roller surface has been increased to ensure that driving force is completely transmitted from the drive roller to the conveyor belt.

(Example) The present invention will be explained below based on the illustrated example. 1st
The figure is a schematic configuration diagram of an image forming apparatus to which a first embodiment of the present invention is applied. A primary charger 3 is installed around the photoreceptor drum 2. Developing device 4. A cleaner 5 and a static elimination lamp 6 are provided to constitute an image forming station. Further, 7 is a laser scanner, and the 1/-the light emitted from the laser scanner 7 is reflected by a mirror 8 to form an electrostatic latent image on the photoreceptor drum 2.

Then, the rotating photosensitive drum 2 is used in a developing device 4 to obtain a visualized image using toner using a known electrophotographic method.

Further, the transfer material 19 cut into the standard size is placed in the cassette 1.
The pickup roller 20. By rotationally driving the registration rollers 21, the sheets are transported one by one into the main body l of the apparatus.

A transfer belt 9 as a conveyor belt is installed in the apparatus main body l by a drive roller 10 and a driven roller 11.The transfer belt 9 is given an appropriate tension by a tension roller 12. A transfer charger 13 is disposed directly below the contact portion between the transfer belt 9 and the photosensitive drum 2. A pressing roller 22 is in pressure contact with the transfer belt 9 wound around the driven roller 11.

Further, a roller 14 as a rotary pressing member is arranged in parallel with the drive roller 10, and the warp 14 is rotatably attached to an arm 15, and the arm 15 is rotatably mounted on a fixed shaft 16. .

The roller 14 is brought into pressure contact with the transfer belt 9 wrapped around the drive roller 10 when the arm 15 is pressed by the force of the spring 17 and rotates about the fixed shaft 16 .

In the above configuration, there are two registration rollers in the transfer material conveyance system.
The transfer material 19 sent out by the transfer roller 1 is held between the pressing roller 22 and the transfer belt 9 wrapped around the driven roller 11, and is conveyed to the contact point between the photosensitive drum 2 and the transfer belt 9, that is, the transfer position. . Then, the visualized image on the photosensitive drum 2 described above is transferred onto the transfer material 19 that has been conveyed to the transfer position by the operation of the transfer charger 13. Thereafter, the transfer material 19 to which the visualized image has been transferred is charged by the transfer charger 13 and is attracted to the transfer belt 9 and conveyed. Next, when the transfer material 9 reaches the end of conveyance by the transfer belt 9, since the radius of curvature of the drive roller 10 is set to be small, the leading edge of the transfer material 9 resists the adsorption force of the transfer belt 9. The transfer material is separated from the surface and sent into the fixing device 24 by the separation claw 23 which is a transfer material separation member. Thereafter, the transfer material 19 on which the visualized image has been fixed by the fixing device 24 is discharged from the discharge port 25 onto a tray 26 provided outside the main body l of the apparatus.

According to the two-legged embodiment, when the transfer belt 9 is brought into pressure contact with the surface of the drive roller 10 by the roller 14 in the conveyance system, the surface pressure of this pressure contact portion becomes significantly higher than that of other parts.

FIG. 2 shows a second embodiment of the present invention, and the same members as in the first embodiment will be described with the same reference numerals. In the same figure, the drive roller 10 and the stay 45 are attached to the side plate (not shown) of the main body l of the apparatus, and the stay 45 arranged in parallel with the drive roller lO has an arm 42 centered on the rotation shaft 44 as shown in the arrow. It is pivoted so that it can rotate in the A direction.

Several rollers 40, 40 as rotary press members are provided at both corners of the upper end of the arm 42 via a shaft portion 41, and the shaft portion 41 is supported by a rib 43 formed approximately at the center of the upper portion of the arm 42. ing. Therefore, the shaft portion 41 can swing in the direction of arrow B around the rib 43. The arm 42 is biased by a spring 46 and rotates around a rotation axis 44 at a roller 40.40.
is rotated in the direction of arrow A' and brought into pressure contact with the transfer belt 9. Therefore, the difference in surface pressure caused by the left and right rollers 40.degree. 40 that are pressed together is equalized by the swinging of the shaft portion 41 supported by the rib 43, which is a pressure correction means, in the B direction.

In the above configuration, when the drive roller 10 is rotated,
The installed transfer belt 9 is rotated, and the rollers 40, 40 pressed against the transfer belt 9 also start driven rotation at the same time.

Here, the pressure contact force of the rollers 40' and 40 is equal to the pressure of the transfer belt 9.
This only increases the surface pressure between the drive roller 10 and the drive roller 10, but does not affect the drive.

In the embodiments described above, the number of rotary press-contacting members is arbitrary, but in this case, it is necessary to prevent pressure differences from occurring at the press-contact points of the respective rotary press-contact members. Incidentally, when this is configured with a plurality of rotary pressing members, unless a pressure correction means as shown in the second embodiment is incorporated, the difference in pressure between the left and right sides of the transfer belt will cause the transfer belt to "twist". This is because

(Effects of the Invention) The image forming apparatus according to the present invention has the above-described configuration and operation, and the portion pressed by the rotating pressure contact member can be held at a higher surface pressure than other conveyor belt portions. ,
Even on a conveyor belt that cannot be subjected to strong tension in order to avoid creep distortion, it is possible to obtain a strong anchoring effect between it and the drive roller, making it possible to sufficiently transmit the driving force from the drive roller to the conveyor belt. be. In addition, even if dirt such as toner adheres to the surface of the drive roller, the anchoring effect described above does not deteriorate significantly, and stable conveyance performance can be obtained over a long period of time, making it possible to maintain high-quality recorded images. This effect is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a laser beam printer to which a first embodiment of the present invention is applied, and FIG. 2 is a perspective view of essential parts showing a second embodiment of the present invention. Explanation of symbols 9...Transfer bell) (II feeding belt) lO...Drive roller 11...Followed roller 13...Transfer charger 14...Roller (rotating pressure contact member) 40...Roller (Rotating pressure welding member)

Claims (2)

[Claims] (1) In an image forming apparatus that forms an image by transferring an image formed at an image forming station onto a transfer material conveyed to the image forming station by a conveyor belt, a controller for driving the conveyor belt is provided. 1. An image forming apparatus comprising: a drive roller; and a rotary pressing member disposed in parallel with the drive roller to press and hold the conveyor belt against the drive roller. (2) The image forming apparatus according to claim 1, wherein a plurality of the rotary pressure contact members are arranged in the width direction of the conveyor belt, and have pressure correction means so that the pressure contact members have equal surface pressure at the pressure contact points. .