JPS63298362A - Image forming device - Google Patents

Abstract

PURPOSE:To form a good image whose position is not dislocated at the time of transfer, by providing a speed detecting means and a load applying means, which applies the same load as the speed detecting means and is rotated asynchronously with the speed detecting means, on both ends in the transverse direction of a carrying belt. CONSTITUTION:A speed detecting means 10 which is rotated synchronously with the movement of a carrying belt 6a and has detecting rolls 10a and 10b is provided on one end in the transverse direction of the carrying belt 6a. A load applying means 11 which applies the same load as detecting rolls 10a and 10b to the carrying belt is provided on the other end in the transverse direction of the carrying belt 6a to approximately equalize loads for carrying in both end parts in the transverse direction of the carrying belt. They are so constituted that detecting rolls of the speed detecting means 10 and the load applying means 11 are rotated asynchronously with each other. Thus, the bending of one end of the carrying belt 6a or the occurrence of creases is prevented to remarkably reduce the occurrence of the dislocation of the transfer image.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a method for forming an image by transferring an image formed on an image carrier onto a transfer material placed on a conveyor belt and conveyed. The present invention relates to an image forming apparatus that has a plurality of image carriers and is capable of forming a multicolor image or a color image on the same surface of the same transfer material.

(Prior Art) A transfer material conveying device conventionally employed in this type of image forming apparatus, particularly in an apparatus capable of forming a multicolor image by arranging a plurality of image carriers in parallel, is shown in FIG. There is something like this. In the figure, 101 is a drive roller 102
It is an endless conveyor belt that moves in the direction of the arrow as the transfer material P is placed and conveyed. Further, in a normal image forming apparatus, in order to transfer an image from an image carrier in synchronization with the conveyance of the transfer material P, the conveyance belt 101 is equipped with a conveyance speed detection means. AtIi, the rotary encoder 103 is used as this detection means.
, and common in terms of cost. As a configuration for inputting speed information to this rotary encoder 103, a speed pickup roller 104 in which rollers 104a and 104'b are integrally connected by a rotating shaft 104c is connected to the rotary encoder 103, and the pickup rotor 104 is conveyed. The belt 101 is disposed in contact with the upper surface thereof, and the backup roller 105 is disposed in contact with the lower surface thereof.

(Problems to be Solved by the Invention) In the conventional example, the rollers 104a and 104b are placed in contact with both ends of the conveyor belt 101 in the width direction so as not to interfere with the conveyance of the transfer material P. The rollers 104a and 104b are arranged in contact with each other, and both rollers 104a and 104b are connected to the rotating shaft 104c.
Since both rollers 10 are integrally connected, it is natural that both rollers 10
4a and 104b rotate synchronously. However, there is a slight difference in the outer circumferential length of the roller 104a and the roller 104b due to the manufacturing process, and the conveyor belt (10) has a length sufficient to convey the transfer material P in the width direction.
1, the outer circumferential length divided into both ends is only D-9.
Therefore, when the conveyor belt 101 is conveyed by rotating the roller 102, for example,
Due to the above-mentioned difference in the outer circumferential length at both ends in the width direction of the conveyor belt 101, the orthogonal edge stand perpendicular to the belt conveyance direction may be inclined as shown by the orthogonal edge line 'in the figure. Due to the inclination of the orthogonal edges, the conveyor belt lO1 may wrinkle before the rollers 104a and 104b.
In cases where there is a difference in the outer circumferential lengths of 04a and 104b, the difference appears to be even larger.

When the transfer material P is positioned on the soil (conveyor belt) 101 and conveyed in this way, the wrinkles of the conveyor belt 101 cause the position of the transfer material P to shift, and the transfer material P is transferred from the image carrier (not shown). There is a problem in that the image shifts from a predetermined position, and even if this shift is slight, in a multicolor or color image forming apparatus having a plurality of image carriers, the problem is that it becomes particularly noticeable as color blurring. Ta.

Therefore, as shown in Fig. 6, in order to solve the problem caused by the above-mentioned image shift, the rollers that come into contact with the conveyor belt are
As a stand, it is possible to consider measures to reduce the negative effects caused by the difference in the outer circumferential length of the rollers, but in this case there is only one roller in contact, so there is no negative effect due to the difference in the roller diameters, but the roller 106'! ! 1) Transport bell on the side in contact) 10
1 had wrinkles, and it was not possible to completely eliminate the positional shift of the image transferred onto the transfer material P.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to increase the speed of the conveyor belt even if there is a slight difference in the outer circumferential length at both ends in the width direction of the conveyor belt. slack in front of the detection roller,
It is an object of the present invention to provide an image forming apparatus capable of forming good images without wrinkles, preventing displacement of a transfer material, and without image displacement.

(Means for Solving the Problems) In order to achieve the above object, an image forming apparatus according to the present invention provides a transfer material that carries a developed image formed on an image carrier on a conveyor belt. In an image forming apparatus that forms an image by transferring an image onto the conveyor belt, a speed detecting means having a detection roller that rotates in synchronization with the movement of the conveyor belt is provided at one end in the width direction of the conveyor belt, and It is constructed by equipping the other end with a load applying means that applies substantially the same load as the load that the detection roller applies to the conveyor belt and rotates asynchronously with the detection roller.

(Function) In the present invention having the above configuration, a speed detecting means having a detection roller that rotates in synchronization with the movement of the conveyor belt is provided at one end in the width direction of the conveyor belt on which the transfer material is placed and conveyed. , by providing a load applying means for applying substantially the same load as the load applied to the conveying belt by the detection roller at the other end of the conveying belt in the width direction, the load on conveyance at both ends of the conveying belt in the width direction is made approximately equal. This prevents sag or wrinkles from occurring at one end of the conveyor belt due to imbalance in the load at both ends of the conveyor belt. Furthermore, by configuring the detection roller of the speed detection means and the load applying means to rotate asynchronously, even if there is a slight difference in the outer circumferential length at both ends in the width direction of the conveyor belt, this difference is The detection means and the load applying means absorb the difference separately so that the difference in outer circumference length is not concentrated in front of the speed detection means,
Prevents wrinkles from forming.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 2 is a configuration diagram showing a four-drum full-length image forming apparatus according to the present invention, and in the same figure, IY, LM,
IC, IBK are yellow, magenta, cyan, respectively.
A photosensitive drum serving as an image carrier in each image forming station is equipped with a developer (toner) of each color of black. These photosensitive drums IY, IM, IC, and IBK rotate in the direction of the arrow in the figure.
, LM, Ic, and IBK are surrounded by primary chargers 2Y, 2M, and 2G for uniform charging.

2BK, and a reflecting mirror unit 31Y that reflects the light beam L from the scanning optical devices 3Y, 3M, 3G, and 3BK to the scanning optical devices 3Y, 3M, 3C, and 38 as image writing means (latent image forming means).

31M, 31G, 31BK, developer 4Y that visualizes the latent image with toner, 4M, 4C, 4BK, cleaner 5Y, 5
M, 5G, 58K, transfer charger 6bY, 6bM, 6bC
, 6bBK are arranged respectively. In addition, the transfer material P is
It is supported on the conveyor bell) 6a and conveyed in the direction of the arrow,
At each of the image forming stations, toner images of each color are sequentially transferred to form a color image, and after the transfer process is completed, the image is fixed by a fixing device 8 and discharged onto a tray 9.

FIG. 1 is a schematic perspective view showing the conveyance system for the transfer material P of the above embodiment. As shown in the figure, in this embodiment, the conveyor belt 6a is wound around rollers 61, 62 and 63 and moves in the direction of the arrow, and a speed detection roller is located downstream of the conveyor belt 6a in the conveyance direction of the transfer material P. 10a and 10b are conveyor bells) 6
The rotating shaft 10c of the speed detecting roller 10a is connected to the rotary encoder lOd, and the speed detecting means lO is configured as described above. Therefore, when the conveyance bell) 6a moves in the direction of arrow A, the speed detection roller 1
0a contacts the conveyor belt 6a and rotates as a result, and a pulse signal corresponding to this rotational speed is sent to the rotary encoder 10.
d is output to a control system that controls the operation of the entire device.

As shown in the figure, by providing the speed detecting means 10 at one end of the conveyor belt 6a, a load is applied against the movement of the conveyor belt 6a. This load may be extremely small, or even if there is a slight lag between the conveyance of the transfer material P and the timing of transferring the image on the photosensitive drum, as in the case of the above-mentioned full-color image forming apparatus, etc.
In an apparatus in which color misregistration is noticeable, the influence of a minute load cannot be ignored as described in the conventional example.

Therefore, in this embodiment, in addition to the above configuration, detection rollers LOa, 1Ob of the speed detection means 1O are provided at one end of the conveyor belt 6a on the side opposite to the side on which the speed detection means 10 is provided in the l] direction. A load applying means 11 is provided for applying a load approximately equal to the load applied by applying pressure to the conveyor belt 6affim. This load applying means 11 applies a load by pinching the conveyor belt 6a with a pair of rollers 11a and 11b, and is configured to press the pair of rollers 11a and 11b into contact with each other using a spring or the like.

Further, a pair of rollers 11a of the load applying means.

iib is the roller loa of the speed detection means 10;

10b, and is configured to rotate completely asynchronously.

Therefore, according to this embodiment, there is no load imbalance at both ends in the width direction of the conveyor belt 6a, and therefore, one end of the conveyor belt 6a is not bent or wrinkled. Therefore, the risk of misalignment of the transfer material P and misalignment of the transferred image is extremely small.Also, since the speed detection rollers 10a and 10b and the load rollers 11a and llb can rotate asynchronously, Even if the conveyor belt 6a has a slight difference in outer circumferential length at both ends in the 10 directions, the slack in the conveyor belt roller a caused by this difference in outer circumferential length is removed before the speed detecting means 10. It does not cause wrinkles due to concentration, and there is no risk of displacement of the transfer material P.
Therefore, the transfer material P is not tilted with respect to the conveyance direction, and the positional deviation between the images transferred individually at the image forming stations of each color can be extremely small, and a good image can be formed.

FIG. 3 is a schematic perspective view showing another embodiment of the present invention,
Components that are the same as those in the embodiment shown in FIG.
A transfer body (intermediate transfer body) 64 in which images mutually supported on BK, IC, LM, and IY are integrally formed on a conveyor belt 6a
The intermediate transfer member 64 used in this embodiment may be a polyester film, urethane film, silicone rubber film, etc. is suitable. Note that the configuration and operation other than those described above are the same as those of the embodiment shown in FIG. 1, so the explanation thereof will be omitted.

FIG. 4 is a schematic gallery view showing still another embodiment of the present invention, and the same components as those in the embodiment shown in FIG. 1 are given the same reference numerals. The conveyor belt is wound around a take-up roll and also serves as a transfer material, and furthermore, a speed detection roller and a load roller are disposed between the photosensitive drums LC and LM. Note that the functions of the configuration 1 other than those described above are the same as those of the embodiment shown in FIG. 1, so a description thereof will be omitted.

In the above embodiments, an image forming apparatus using an electrophotographic process has been described, but the present invention is not limited thereto, and can also be applied to image forming apparatuses using a thermal transfer method or a printing plate method. Can be done.

Further, in the above embodiment, a configuration was described in which the conveyor belt was pinched by a pair of rollers as a load applying means, but the present invention is not limited to this, and a uniform configuration in which the conveyor belt is pinched by a flat bat is also applicable. 1゜ (Effects of the Invention) The present invention has the above-described configuration and operation, and applies substantially equal loads to both ends of the conveyor belt in the width direction, respectively, to the speed detecting means, and to the speed detecting means. By providing a load applying means that rotates asynchronously, the conveyor belt is prevented from becoming cantilevered and sagging, and this slack is prevented from becoming wrinkled in front of the speed detecting means, thereby eliminating misalignment of the transfer material. Therefore, it is possible to form a good image without misalignment of the transferred image.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing essential parts of an embodiment of an image forming apparatus according to the present invention, FIG. 2 is an overall configuration diagram of the embodiment, and FIG.
The figure is a schematic perspective view showing another embodiment, FIG. 4 is a schematic perspective view showing still another embodiment, FIG. 5 is a schematic perspective view showing a conventional example, and FIG. 6 is a schematic perspective view showing another conventional example. FIG. Explanation of symbols IBK, IC, IM, IY...Photosensitive drum (image carrier)

Claims (1)

[Claims] In an image forming apparatus that forms an image by transferring a developed image formed on an image carrier onto a transfer material that is placed on a conveyor belt and is conveyed, a belt is attached at one end in the width direction of the conveyor belt. A speed detection means having a detection roller that rotates in synchronization with the movement is provided, and a load that is substantially the same as the load that the detection roller applies to the conveyance belt is applied to the other end in the width direction of the conveyance belt, and the speed detection means rotates asynchronously with the detection roller. An image forming apparatus characterized in that it is equipped with a load applying means.