JPH01300279A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain excellent flexibility by lowering the rigidity of a guidance rib against the advance direction of a transfer belt by forming the guidance rib fixed to the transfer belt of a transfer belt means to a rack teeth shape. CONSTITUTION:On the inside peripheral surface side of one side end part in the long size direction of a belt ground fabric 100A of a carrying belt 100 of a carrying belt device 7, a guidance rib 101B having a rack teeth-shaped projecting part 101 is stuck except an area where an image is formed, and a guide groove 11A is provided so as to correspond to this guidance rib 101B. In such a way, since the rack-shaped rack teeth 101 are provided on the guidance rib 101B, as for thrust force applied from the width direction, unchangeable rigidity is held, and on the other hand, as for stress applied in the advance direction of the carrying belt 100, rigidity of a guidance rib thickness portion is obtained, and the flexibility is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus such as an electrophotographic apparatus or a laser beam printer that forms image information on an image support 1 such as a transfer material, and particularly relates to an image forming apparatus such as an electrophotographic apparatus or a laser beam printer. The present invention relates to a color image forming apparatus that forms a color image by juxtaposing two or more image forming processes.

Several systems have been proposed for color electrophotographic copying bags using an electrophotographic method in which color images are formed using a plurality of image forming processes. One of the typical methods is shown in FIG. The color electrophotographic copying bag shown in FIG. 5 is equipped with four image forming stations Pa, Pb, Pc, and Pd. Drums la, lb, lc, and ld are provided. Each photosensitive drum has a dedicated charging section 2a along its rotation direction.

2b, 2C12d, exposure section 3a, 3b, 3C13d, developing section 4a, 4b, 4c, 4d, transfer section 5a, 5b,
5c, 5d, cleaning parts 6a, 6b, 6c, 6d
is located.

On the other hand, each image forming station Pa, Pb, Pc, Pd
Each photosensitive drum la, lb, lc, l
An endless belt-shaped transfer belt means, that is, a conveyor belt means 7 is disposed below d, and transfer material 9 fed by a paper feed roller 8 disposed at one end of the transfer belt means is transferred to each image forming station Pa, Pb, Pc, Pd transfer portion 5a
, 5'b, 5C15d.

To describe the formation of a color image in the color electrophotographic copying apparatus having the above configuration, first, using the charging section 2a and the exposure section 3a of the first image forming station Pa, a photosensitive drum is formed by known electrophotographic means. After forming a latent image of the yellow component color of the original image on la, the developing section 3a converts the latent image into a visible image using a developer containing yellow toner, and transfers the latent image to the transfer material 9 conveyed by the conveyor belt means 7. The visible yellow toner image is transferred in the transfer section 4a.

Then, while this yellow toner image is being transferred to the transfer material 9, at the second image forming station Pb, the photosensitive drum lbh is
A latent image of the magenta component color of the original image is formed on the transfer material, then a magenta toner image is obtained using magenta toner in the developing section 4b, and then the yellow toner image has been transferred to the transfer material at the first image forming station Pa. 9 is carried into the transfer section 5b of the second image forming station Pb, this magenta toner image is transferred to a predetermined position on the transfer material 9 onto which the yellow toner image has been transferred.

Image formation is subsequently performed in the same manner for cyan and black colors, and when the four-color toner images have been superimposed on the transfer material 9, the transfer material 9 is placed on the other end side of the conveyor belt means 7. The image is conveyed to the fixing section 10 and fixed there, and a multicolor (full color) image is obtained on the transfer material 9.

Each photosensitive drum la, 1b, lc after the transfer has been completed
, ld are cleaned by cleaning means 6a, 6b, 6c, and 6d to remove residual toner remaining thereon in preparation for the next latent image formation to be performed subsequently.

The full color image forming apparatus as described above has the following advantages.

■Each color has its own image forming station, which is advantageous for speeding up.

■Since the transfer path can be configured in a straight line, it is also applicable to transfer materials such as cardboard and transparent film.

However, the biggest drawback is that there is a serious problem in how to properly register each color image formed at different image forming stations.

The deviation in the formation positions of the four colors of images transferred onto the transfer material (hereinafter referred to as registration deviation) ultimately appears as a color deviation or a change in hue. One of the causes of this registration shift is that the transfer belt means (transfer belt means 7, conveyor belt) 100 that conveys the transfer material does not move in a straight line, causing deviation of the conveyor belt 100. Bell) 100 is this transport bell) 100
This is caused by deviation from the prescribed path or meandering on the rollers that rotate, hold, and guide the rollers.

The above-mentioned transfer belt (i.e., conveyance belt) 100 is corrected by the bias correction means.

■Flanges are provided at both ends of the roller that rotates, holds, and guides the conveyor belt.

■The diameter of the center of the roller that rotates, holds, and guides the conveyor belt is larger than the diameter of both ends, giving it a crown shape.

(2) The center of the rotation axis of at least one of the plurality of rollers installed vertically with respect to the direction of travel of the conveyor belt can be set at any angle with respect to the direction of travel of the conveyor belt.

- A sprocket is provided at the end of the roller that rotates, holds, and guides the conveyor belt, and a perforation with the same width as the hit between the sprocket's pawls is provided at the portion of the conveyor belt that corresponds to the pawls of this sprocket.

(A guide groove is provided on each lug that rotationally drives, holds, and guides the conveyor belt, and a guide rib is provided at a portion of the conveyor belt that corresponds to the guide groove.)

There are known techniques such as. In addition, special public service No. 58-17955
As shown in Japanese Patent Publication No. 62-12124, etc., there are techniques that use a combination of the above-mentioned known techniques.

Regarding the above-mentioned known techniques, the first method using a flange has the advantage of having a simple structure, but the end of the moving conveyor belt is pressed against the flange member for positioning. Therefore, the ends of the conveyor belt are always subjected to thrust force, and the conveyor belt has the drawback of being easily deformed and destroyed. In particular, in a conveyor belt using an organic material such as that used in the present invention described later, it is preferable that the thickness of the conveyor belt be as thin as possible from the viewpoint of transfer efficiency. However, when a thick conveyor belt is used, , Because the strength of the ends of the conveyor belt is not sufficient, the conveyor belt is susceptible to deformation and tearing.

Long-term use is essential. Japanese Patent Publication No. 57-60347 and Japanese Patent Publication No. 5, using the same function as the above-mentioned flange.
The same applies to Publication No. 6-156544 and the like.

Next, the second crown shape, which is the most widely used means for correcting the misalignment of a conveyor belt, distorts the conveyor belt at the center of the roller and uses the internal stress difference at that time to correct the misalignment of the conveyor belt. In order to suppress this, the conveyor belt needs to have sufficient elasticity. In order to utilize the distortion of the WI transport belt and prevent permanent deformation of the transport belt due to creep distortion, a material with low hardness and high elasticity is used, and the wall thickness is increased until the mechanical strength is satisfied. However, it is not suitable for use in the above-mentioned conveyor belt due to its wall thickness.

Next, I mentioned the third thing. Rotating and holding the conveyor belt,
The means for changing the angle between the rotation axis center of at least one of the rollers to be guided and the traveling direction of the conveyor belt is particularly effective for conveyor belts with little elasticity, and is effective for changing the thickness of the conveyor belt. Although it has the advantage of not being affected by the deviation of the conveyor belt, it requires a mechanism to detect the deviation of the conveyor belt and a mechanism to move the center position of the roller rotation axis in response to the output from the detection mechanism, making the device complicated and large. have. Furthermore, since the direction of correcting the deviation of the conveyor belt relies on the friction coefficient ap between the conveyor belt and the rollers, there is also the drawback that if the conveyor belt and roller surfaces become dirty and the friction coefficient decreases, no corrective action will occur. Therefore, it cannot be said to be a suitable means for devices that handle toner, such as electrophotographic devices.

Next, in the method using the sprocket and the perforations provided on the conveyor belt to correspond to the claws of the sprocket described in the fourth aspect, the strength of the conveyor belt is required as in the case of using flanges. Furthermore, since the accuracy of the pitch between the pawls of the sprocket and the perforations determines the accuracy of the conveying speed, it is not suitable for a conveying belt that requires a highly accurate conveying speed.

Finally, the fifth method using rollers with guide grooves and belts with guide ribs is a simple mechanism, but it is possible to suppress deviation of the conveyor belt, and it is possible to suppress the deviation of the conveyor belt. Even when used, the thrust force is applied to the strong guide rib end face, so it is excellent in durability. Conventionally, as mentioned above, rollers with guide grooves and belts with guide ribs have been used as a means for correcting the misalignment of conveyor belts in terms of high precision, high reliability, and miniaturization of the device. The method is considered suitable.

Therefore, also in the color electrophotographic copy shown in FIG. 5, as shown in FIG. Guide grooves 11a-14a are formed in predetermined rows of the conveyor belt drive roller 11 provided for driving the conveyor belt 100 so as to correspond to the guide ribs 10IA of the belt base fabric 100A. are fitted to determine the specified route of the conveyor belt and to ensure the straightness of the conveyor belt.

However, in the above-mentioned conventional conveyor belt offset correction means using a roller with guide grooves and a belt with guide ribs, that is, a conveyor belt meandering correction means, as described above, the guide ribs are attached to the conveyor belt that conveys the transfer material. When the conveyor belt is wrapped around each roller, due to the difference in thickness of the conveyor belt and the difference in hardness between the conveyor belt material and the guide rib material,
The part of the conveyor belt to which the guide ribs are fixed has inferior flexibility compared to the part of the conveyor belt to which the guide ribs are not fixed.
At the contact portion between the conveyor belt and each roller, the portion of the conveyor belt that was fixed, such as a guide rib, did not completely adhere to the roller and was lifted up.

In this way, the guide ribs lifted from the rollers are
It becomes easy to run onto the roller surface from the guide groove provided on the roller, making the straightness of the conveyor belt unstable, and as a result,
This causes a significant change in the transfer material transport path from the specified path. Furthermore, each time the guide ribs riding on the roller surface return to the guide groove, the vibrations generated at that time are transmitted to the conveyor belt, causing fluctuations in the conveyance speed of the conveyor belt.

The above-mentioned phenomenon also occurs in the drive roller section that drives the conveyor belt, and as a result, the contact area between the conveyor belt and the drive roller is reduced, and the scattered toner is attached to the roller surface and rotates, causing the roller surface to become damaged. This resulted in a decrease in the frictional coefficient etp-, making the drive transmission to the conveyor belt extremely unstable.

This leads to registration misalignment, which appears as color bleeding or a change in hue.
This will significantly degrade the quality of the image.

Therefore, in order to suppress the lifting of the guide ribs from the rollers mentioned above, it is sufficient to increase the tension applied to the conveyor belt. However, if the guide ribs and the conveyor belt are made of resin, increasing the tension too much may cause creep. This causes distortion, deforming the guide ribs and the conveyor belt at the parts that adhere to each roller when the device is stopped, making it impossible for the conveyor belt to carry smoothly. Since the elongation of this part and other parts of the conveyor belt are different, stress such as shear force is applied to the guide rib fixing part, which has the disadvantage of shortening the life of the conveyor belt.

Therefore, an object of the present invention is to prevent the transfer belt that conveys the transfer material for transferring the image to be transferred from shifting or meandering, with a simple configuration, and to ensure stable and smooth movement of the transfer belt. The present invention provides a transfer belt means that can perform a conveyance operation and that can obtain images with good image quality that do not cause registration shift when transferring multiple images, and therefore do not cause color shift or change in hue. Equipped with image formation? eW
1.

Another object of the present invention is that the guide rib portion for guiding the transfer belt fixed to the transfer belt of the transfer belt means has good flexibility without lifting off from the roller for driving, holding and guiding the transfer belt. Therefore, it is an object of the present invention to provide an image forming apparatus equipped with a transfer belt means that can be brought into good close contact with a roller, the transfer belt can be reliably driven and conveyed, and an image with good image quality can be obtained.

Another object of the present invention is to provide a long-life transfer belt that does not cause creep distortion in the transfer belt portion to which guide ribs are fixed in the transfer belt means, and therefore does not cause deformation or breakage in the transfer belt portion. An object of the present invention is to provide an image forming bag equipped with a transfer belt means.

for The above objects are achieved by the image forming apparatus of the present invention.

That is, to summarize, the present invention provides an image forming apparatus that includes an image carrier on which an image is formed according to document information, and a transfer belt unit that transfers the image formed on the image carrier to a transfer material. In this, the transfer belt means includes a transfer belt and a plurality of rollers formed with guide grooves and around which the transfer belt is wound, and the transfer belt includes a belt base fabric for conveying the supplied transfer material. , an image forming apparatus characterized in that the image forming apparatus includes guide ribs in the shape of two ruffled teeth fixed to the belt base fabric portion corresponding to the guide grooves of each of the rollers. It is located at c.

Accordingly, one aspect of the present invention is to reduce the rigidity of the guide ribs in the direction of movement of the transfer belt by forming the guide ribs fixed to the transfer belt into a rack-tooth shape.
With respect to the force applied from the lateral direction of the transfer belt, it can be said that the rack-tooth-shaped protrusions maintain almost the same rigidity as a conventional belt having guide ribs.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described by way of example only and with reference to the accompanying drawings.

First, referring to FIG. 2, a color image forming apparatus according to the present invention is shown. As shown in FIG. 2, the color electrophotographic copying apparatus as a color image forming apparatus has four image forming stages, yPa, Pb, and Pc.
, Pd, and each image forming station has a dedicated rotating photosensitive drum l serving as an image carrier.
a, lb, lc, and ld are arranged. Around each photosensitive drum, dedicated charging sections 2a, 2b, 2C12d, exposing sections 3a, 3b, 3
c, 3d, developing section 4a, 4b, 4c, 4d, transfer section 5a, 5b, 5c, 5d, cleaning section 6a, 6b,
6c and 6d are placed.

On the other hand, each image forming station Pa, Pb, Pc, Pd
Each photosensitive drum la, lb, lc, l
Below d, an endless belt-like transfer belt means, that is, a conveyor belt device M7 as a conveyor belt means is arranged, and a transfer material 9 fed by a feed roller 8 disposed at one end of the transfer belt device M7 is arranged. Each image forming station Pa, Pb
, Pc, and Pd.

In such a color electrophotographic copying apparatus, a color image is formed as follows.

That is, first, the first image forming station Pa
After forming a latent image of the yellow component color of the original image on the photosensitive drum la by a known electrophotographic means using the charging section 2a and the exposing section 3a of The latent image is made into a visible image, and the yellow toner image made into a visible image is transferred in the transfer section 4a onto the transfer material 9, which is conveyed by the conveyor belt device N7.

Then, while this yellow toner image is being transferred to the transfer material 9, at the second image forming stage Pb, the magenta component color of the original image is transferred onto the photosensitive drum lb in the same way as in the case of the yellow toner image. A latent image is formed, and then a magenta toner image is obtained using magenta toner in the developing section 4b, and the transfer material 9, on which the yellow toner image has been transferred at the first image forming station Pa, is transferred to the second image forming station Pb. When the magenta toner image is transferred to the transfer section 5b, the magenta toner image is transferred to a predetermined position on the transfer material 9.4z onto which the yellow toner image has been transferred.

Thereafter, image formation is performed in the same manner for cyan and black colors, and when the superposition of the four color toner images on the transfer material 9-A is completed, the transfer material 9 is placed on the other end side of the conveyor belt device N7. The image is conveyed to the fixed fixing unit 10 and fixed there, and a multicolor (full color) image is obtained on the transfer material 9.

On the other hand, the photosensitive drums la and lb on which the transfer has been completed
, lc, ld are cleaning means 6a, 6b, 6C1
At step 6d, any residual toner remaining thereon is removed in preparation for subsequent latent image formation.

Here, the conveyance belt assembly M7 for conveying the transfer material used in the above-mentioned color image forming apparatus will be further explained with reference to FIG.

As shown in FIG.
1 and conveyor belt guide and holding rollers 12 to 14, and the rotation of the drive roller 11 causes the conveyor belt to rotate.
00 is activated.

Guide ribs 1oiB having rack tooth-shaped protrusions 101 are adhered to the inner circumferential surface of the longitudinal side end portion of the belt base fabric 100A constituting the conveyor belt 100 outside the area where an image is formed. In order to correspond to this guide rib 10IB, the stirrup at a predetermined position of each roller 11-14 has a
Guide grooves 11A to 14A of the guide rib 10IB are provided.

Here, the belt base fabric 100A used in the above-mentioned conveyor belt device 7 has the adsorption property, transferability, etc. of the transfer material.
A flexible and low-rigid urethane thermosetting resin (tensile modulus 4500 Kg/crn', volume resistivity to
+2~lQ 14Ω-cm), and the guide rib 10IB having a rack tooth-shaped protrusion Lot with a substantially rectangular cross section as shown in Fig. 3 and w43a is:
In consideration of using a urethane adhesive having elasticity and fatigue resistance when adhering to the belt base fabric 100A, a urethane resin made of the same material as the conveyor belt is used.

In addition, the pitch between the pitches and the root widths of the rack tooth-shaped protrusions lots provided on the guide rib 101B described above are suitably determined by the diameter of the minimum roller around which the conveyor belt 100 is wound. When the conveyor belt is wound around the diameter,
The projections, that is, the rack teeth 101 are set so as not to come into contact with each other.

In this way, by providing the above-mentioned rack-shaped rack teeth lO1 on the guide rib l0IB, the transport bell) 100
While maintaining almost the same rigidity as the conventional guiding rib shape against the thrust force applied from the side, that is, from the width direction, the transport belt 100 and the roller 2 maintain the same rigidity as the conventional guide rib shape. The rigidity is equal to the thickness of the guide rib at the bottom of the tooth 101, and the effect of improving flexibility can be obtained.

Therefore, due to the above-mentioned effect, even when the tension of the conveyor belt lOO is weak, the portion of the conveyor belt to which the guide ribs l0IB are fixed follows the rollers, that is, the conveyor belt lOO follows the guide grooves 11A-14A of each roller. Since the guide ribs are conveyed, it is possible to completely prevent the guide ribs from riding on the roller surface, which was a drawback in the past. Moreover, since the guide rib has rack teeth 1O1 provided with fine peas, the rack teeth 101 are in the guide groove at the contact portion of each roller 11-14 around the guide groove 11A-14A. In order to closely follow the curvature of the guide groove IIA-14A of each roller IIA-14A, the conveyor belt 100 that the guide rib originally has
It is possible to obtain stable running of the conveyor belt without any loss in the misalignment correcting action of the transfer belt, and therefore, it is possible to obtain high-quality multiple transfer images, and the reliability of the image forming apparatus is significantly improved. becomes possible.

In the present invention, the rack tooth shape provided on the guide rib is 1
For example, as shown in FIGS. 4 and 4a, the side surfaces of the rack teeth having a substantially rectangular cross section are chamfered, thus forming a guide rib l0Ic in which the side surface of the guide rib is chamfered. The shape of the protrusion, that is, the shape of the rack teeth, can be any shape. Furthermore, the effects of the present invention can be obtained regardless of the method of fixing the guide ribs to the conveyor belt, such as adhesion, welding, or simultaneous molding with the conveyor belt.

As described above, according to the image forming L& device of the present invention, the guide ribs fixed to the transfer belt of the transfer belt means are formed into a rack tooth shape, so that the direction of movement of the transfer belt is The stiffness of the guide ribs is reduced to prevent the transfer belt from lifting off from the rollers that drive, hold, and guide the transfer belt, and to reduce the stiffness of the guide ribs against The rack tooth-shaped protrusions maintain almost the same rigidity as conventional guide ribs, so the transfer belt has excellent flexibility and adheres well to the a-ra, ensuring reliable drive. While being transported, it is possible to prevent the transfer belt from shifting or meandering, and therefore the transfer belt can be transported stably and smoothly, and when transferring multiple images, there is no registration misalignment. It is possible to obtain an image with good image quality without one color shift or change in hue.

Furthermore, the transfer belt to which the guide ribs are fixed in the transfer belt means used in the image forming apparatus of the present invention and the guide ribs are not subjected to undesirable force while conveying the transfer material, so that creep distortion does not occur. Therefore, the transfer belt has a long life without causing deformation or destruction of the transfer belt portion having the guide ribs.

[Brief explanation of the drawing]

FIG. 1 is a schematic partial perspective view of transfer belt means used in the image forming apparatus of the present invention. FIG. 2 is a schematic cross-sectional explanatory diagram of the image forming apparatus of the present invention. FIG. 3 is a partial vertical cross-sectional view of a guide rib fixed to the transfer belt means of FIG. 1. FIG. FIG. 3a is a sectional view taken along line xx' in FIG. 3. FIG. 4 is a partial vertical sectional view of another embodiment of the guide rib fixed to the transfer belt means of FIG. 1. FIG. 4a is a sectional view taken along line Y-Y' in FIG. 4. FIG. 5 is a schematic cross-sectional view of a conventional image forming apparatus. FIG. 6 is a schematic partial perspective view of a transfer belt means used in a conventional image forming apparatus. la, lb, lc, ld: Image carrier 7: Transfer belt means 9: Transfer material 11.12.13.14: Rollers 11A, 12A, 13A, 14A: Guide groove 100: Transfer belt 100A: Belt base fabric 101: Projections 101B, l0Ic: Guide ribs Fig. 1 Fig. 2 Fig. 3 Fig. 3 0 Fig. 4 Fig. 4 O 1o1c”

Claims (1)

[Claims] 1) In an image forming apparatus including an image carrier on which an image is formed according to document information, and a transfer belt means for transferring the image formed on the image carrier to a transfer material, the transfer belt means: The transfer belt has a plurality of rollers formed with a transfer belt and a guide groove around which the transfer belt is wound, and the transfer belt includes a belt base fabric for conveying the supplied transfer material, and a guide groove of each roller. An image forming apparatus comprising: a rack tooth-shaped guide rib fixed to a corresponding portion of the belt base fabric.