JPS6311967A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate color slippage, by arranging two or more image carriers which are driven by common driving means at prescribed distances from each other so that the time required by a moving means for moving from the transferring position of one image carrier to that of the adjacent image carrier goes to integral times as long as the unevenly driven period of the driving means. CONSTITUTION:Photosensitive drums 1-3 which are driven by common driving means 17 and 29 are arranged at prescribed distances from each other, but the distances are set in such a way that the times T1 and T2 required by a transfer material carrying means 13 and transfer material 24 to move from the transferring position 25 of the drum 1 to that 26 of the adjacent drum 2 and from the transferring position 26 of the drum 2 to that 27 of the adjacent drum 3 go to integral times as long as the unevenly driven period of driving means 17 and 29. When, for example, a picture is transferred to the transfer material 24 in an expanded state at the transferring position 25 of the drum 1, pictures of the drums 2 and 3 are transferred to the transfer material 24 in expanded states at the transferring positions 26 and 27 of the drums 2 and 3. Therefore, transfer slippage at each image forming station can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a color image forming apparatus, and more particularly, a plurality of image carriers such as electrophotographic photoreceptors are arranged side by side, and an electrophotographic image is formed on these photoreceptors. A forming process is performed to obtain a developed image of each color, and the developed image is sequentially transferred to a transfer material carried and conveyed by a transfer material conveying device, an intermediate transfer body, or an image receptor such as continuous paper to obtain a color image. 6 The present invention relates to a multicolor electrophotographic image forming apparatus, and can be realized not only in an electrophotographic color copying apparatus but also in various color printers, etc., but in this specification, a laser beam applying electrophotography will be described. This will be explained in relation to printers. The image carrier used in the present invention may be in any form, such as a belt or a drum, as long as it moves endlessly; however, in this specification, a drum-shaped image carrier will be described. .

'Z-bi.' Hitherto, several systems have been proposed as electrophotographic laser beam printers.

One of the typical methods is schematically shown in FIG.

According to the full-color laser beam printer shown in FIG. 5, three image forming units Pa, Pb, and Pc are arranged, and each image forming unit has a dedicated photosensitive drum L, 2.3.
around which dedicated image forming process means (other than the laser beam exposure means 7, 8 and 9 are not shown, for example, the band 1 section, the exposure means, the developing section, the transfer section, the cleaning section, etc.). On the other hand, below the photosensitive drum 1.2.3, each image forming unit) Pa, P
b, a transfer material conveying means 13 equipped with a moving body (i.e., an endless bell) 16 suspended from a drum 14, 15 and rotating in the direction of the arrow in a manner penetrating Pc, and a paper feeding device (not shown) Transfer material P fed by each image forming unit)Pa
, Pb, and Pc are configured to be conveyed in the direction of the arrow through the transfer section F1125.26.27.

In this configuration, first, a visible image of yellow toner is formed in the first image forming unit Pa, and then a visible image of yellow toner is formed on the transfer material P conveyed by the transfer material conveying means 16 at the transfer section, that is, at the transfer position 25. A yellow toner image is transferred. On the other hand, while this yellow image is being transferred to the transfer material P, a toner image with magenta toner is obtained on the second image forming unit )Pb, and the transfer is completed on the transfer material P in the first image forming unit)Pa. is of the second image forming unit Pb.

When the transfer material P is carried into the transfer position 26, this magenta toner image is transferred to a predetermined position on the transfer material P.

Image formation is subsequently performed in the same manner for cyan color and, if desired, black color. When the superposition of the three or four color toner images on the transfer material P is completed, the transfer material P is transferred to the fixing section (not shown). It was established in

A multicolor (full color) image is obtained on the transfer material P.

After the transfer has been completed, residual toner is removed from each photosensitive drum by a cleaning means (not shown).

Prepare for the next latent image formation to be performed subsequently.

Such a full-color image forming apparatus is advantageous in increasing speed because it has a separate image forming unit for each color.

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

However, one of the biggest drawbacks is that there are many problems in how to properly register each color image formed by different image forming units.

Misalignment (registration misalignment) in the image forming position t of the three or four colors transferred onto the transfer material ultimately appears as color misalignment or a change in hue. One of the causes of this registration shift is that the starting position of image transfer to the transfer material shifts between the photosensitive drums due to uneven rotational driving of each photosensitive drum.

In order to solve this problem, the present applicant proposed a method of connecting a rotary encoder to the photosensitive drums and accurately controlling the rotation of each photosensitive drum. Although this method was able to obtain good results, the structure and control mode became complicated, and the cost of the image forming apparatus also increased as a result.

The inventors of the present invention have researched methods for driving and controlling photosensitive drums in order to solve such problems. It has been found that the problem can be solved by driving with a single driving means. In addition, inherent driving unevenness (wow and flutter) of the driving means that occurs at this time occurs periodically, and the periodic driving unevenness causes each photosensitive drum driven by the common driving means to move in the adjacent state. It has been found that the problem can be solved by arranging the transfer material conveying means to pass the transfer position of the optical drum so that the time interval for passing the transfer material is equal to an integral multiple of the driving unevenness period of the driving means.

The present invention has been made based on this new knowledge.

Therefore, an object of the present invention is to drive the image carriers by a common driving means, and to eliminate transfer deviation of the image from each image carrier to the transfer material.
That is, it is an object of the present invention to provide an image forming apparatus that can eliminate one-color deviation and obtain high-quality color images.

Another object of the present invention is to provide an image forming apparatus that can obtain high-quality color images by eliminating mistransfer of images from each GL carrier to a transfer material, that is, misregistration of one color, with a simple structure. It is.

to preserve the ancient past The above object is achieved by an image forming apparatus according to the present invention.

In summary, the present invention provides a system in which a plurality of image carriers are arranged side by side and are driven to pass through the transfer position of the holding body in order to sequentially transfer the images formed on each of the image carriers. In an image forming apparatus equipped with a moving means, all of the image carriers or at least two or more of the image carriers are driven by a common drive means, and the image carriers are driven by the common drive means. Each of the image carriers is arranged at a distance # such that the passing time interval of the moving means passing through the transfer positions of the adjoining containers is equal to an integral multiple of the driving unevenness period of the driving means.
The image forming apparatus is characterized in that the image forming apparatuses are arranged at intervals. In a preferred embodiment of the invention, the drive means includes a drive motor and a drive motor driven by the drive motor.
This is a drive shaft that simultaneously transmits driving force to the above image carriers.

The moving means may be a transfer material conveying means for conveying a transfer material for transferring the image formed on the image bearing member, or an intermediate transfer body or roll paper for transferring the image formed on the image bearing member. Ru.

L Presentation 1 Hereinafter, the image forming apparatus according to the present invention will be explained in more detail with reference to the drawings.

A first embodiment of the present invention is illustrated in FIG. 1. In this embodiment, the present invention is embodied in the conventional image forming apparatus described above with reference to FIG. - or equivalent members and portions are designated by the same reference numerals and detailed description thereof will be omitted.

According to the invention, the photosensitive drums 1, 2.3 have at least two
As described above, in this embodiment, all the photosensitive drums are driven by a common driving means. That is, in this embodiment, the drive means includes the electric motor 17 and the drive shaft 29 connected to the drive motor.
It consists of Each photosensitive drum 1, 2.3 has a worm gear 18, 19, 20 provided on the drive shaft 29 and a worm wheel 21, 22.
The rotational driving force from the drive shaft 29 is transmitted via the drive shaft 23 .

Furthermore, according to the present invention, each of the photosensitive drums 1 and 2.3 driven by a common driving means 17.29 are heated at a predetermined distance from each other, and the distance is set between the transfer material conveying means 13 and the photosensitive drums 2.3. In this embodiment, the transfer material P is attached to adjacent photosensitive drums l and 2.
The passing times T1 and Tz (Tz may be the same as T1) for passing between the transfer positions 25 and 26 and 26 and 27 of 2 and 3 are determined by the drive unevenness period of the drive means 17 and 29 (
The distance is set to be an integral multiple of wow and flutter).

To explain further, the inventors of the present invention have found that when the photosensitive drums 1 and 2.3 are driven with the above configuration, the drive means 1°7.29 has drive unevenness at a period of T3 as shown in FIG. In other words, wow and flutter occurs.

The drive unevenness is directly transmitted to the photosensitive drum 1.2.3, and as a result, when the image on the photosensitive drum is transferred to the transfer material passing through the transfer position of the photosensitive drum, the image expands and contracts on the transfer material. According to the present invention, as described above, the photosensitive drums 1, 2.3 are transferred to the transfer material conveying means 13.3, which pass through the transfer positions of the photosensitive drums adjacent to each other.
In other words, the transfer material P is arranged so that the passing time intervals T, TZ are equal to an integer multiple of the driving uneven circumference @TI of the driving means 17.29.

When an image is transferred to the transfer material P in an elongated state at the transfer position 25 of the photosensitive tram 1, the transfer material P is transferred to the next photosensitive drum 2 at the transfer position a26. Also at the transfer position 27 of the drum 3, the images on each photosensitive drum are transferred onto the transfer material P in an elongated state, and transfer misalignment at each image station is eliminated. On the other hand, when the image is transferred to the transfer material P in a contracted state at the transfer position 25 of the photosensitive drum L, the image is transferred to the transfer material P in a contracted state at the transfer position 25 of the photosensitive drum l, as described above. Therefore, the image is transferred onto the transfer material without causing transfer misalignment.

As described above, according to the present invention, the periodic drive unevenness inherent in the drive means for driving the photosensitive drum is completely solved, and therefore the drive motor 1 constituting the drive means in this embodiment
7 and the drive shaft 29 are not required to be as high as conventionally required.

The above embodiment is a multicolor electrophotographic laser beam printer in which a developed image is successively transferred onto a transfer material P carried by a transfer material conveying means 13 having a belt to obtain a color image. However, the present invention can also be embodied in a multicolor electrophotographic image forming apparatus that sequentially transfers a developed image to an intermediate transfer member or an image receiving member such as continuous paper to obtain a color image. Another embodiment of the invention is illustrated in FIGS. 3 and 4.

FIG. 3 shows an image forming apparatus according to the present invention in which an image formed on a photosensitive drum 1, 2.3 is once transferred to an intermediate transfer member, and then a visible image on the intermediate transfer member is transferred to the transfer material. According to this embodiment, which shows a mode realized in the above, the photosensitive drum l
, 2, 3, there is a moving body 1 which is an intermediate transfer body conveying means.
3a, and the intermediate conveying means 13a has substantially the same structure as the transfer material conveying means 13 described in connection with FIG. The only difference is that a belt-shaped polyester film, polyimide film, silicone rubber, urethane rubber, etc. are used. Further, in this embodiment, in order to further transfer the visible image once transferred to the intermediate transfer body 16a onto the transfer material P, the transfer material P fed from a paper feeding device (not shown) is transferred to the intermediate transfer body 18a. In order to press, a transfer roller 14a is used instead of the hanging doshim 14 in FIG.
, 14b are arranged. In this embodiment as well, the same effects as in the embodiment shown in FIG. 1 can be obtained.

FIG. 4 shows a multicolor electrophotographic image forming apparatus in which the present invention is realized by sequentially transferring images formed on photosensitive drums 1, 2, and 3 to an image receptor such as continuous paper Pa to obtain a color image. This shows how it was done. According to this embodiment, the photosensitive drum 1.
2.3, a continuous transfer paper Pa fed out from the transfer roll paper is placed, and the image on the photosensitive drum-E is directly transferred onto the roll paper. That is, in this embodiment, a continuous paper Pa is provided in place of the conveying belt 16 in the transfer material conveying means described in Section F in connection with FIG. 1 above.

Even in a non-embodiment, the same effects as those of the embodiment shown in FIG. 1 can be obtained.

In the above embodiments, the driving force transmission means from the driving means 17.29 to the photosensitive drum is an ohm gear and a worm wheel, but it is not limited thereto, and for example, a bevel gear transmission mechanism may also be used. In addition, other means than the electric motor 17 and the drive shaft 29 may be used as the drive means.

The image forming apparatus according to the present invention configured as described above is
The image carrier can be driven by a drive means that does not require high precision compared to conventional methods, and it is also possible to eliminate mistransfer of images from each image carrier to the transfer material, that is, misregistration of one color. ,
Therefore, high quality color images can be obtained with a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a graph showing drive cycle irregularities of the drive means. FIG. 3 is a perspective view of a second embodiment of the image forming apparatus according to the present invention. FIG. 4 is a perspective view of main parts of a third embodiment of an image forming apparatus according to the present invention. FIG. 5 is a perspective view of a conventional iTj image forming device.
a: Transfer material 1.2.3: Image carrier 13: Transfer material conveyance means 16: Transfer material conveyance belt 16a: Intermediate transfer body 17.29: Drive means 18.19.20: Ohm gear 21.22.23: Worm wheel 25.26.27: Transfer position Fig. 2 Fig. 3 c Fig. 4 c

Claims (1)

[Claims] 1) A plurality of image carriers are arranged side by side, and the image carrier is driven to pass through the transfer position of each image carrier in order to sequentially transfer the images formed on each image carrier. In an image forming apparatus equipped with a moving means, all of the image carriers or at least two or more of the image carriers are driven by a common drive means, and the image carriers are driven by the common drive means. Each of the image carriers is arranged such that a passing time interval of the moving means passing through a transfer position of each adjacent image carrier is a distance interval equal to an integral multiple of a drive unevenness period of the drive means. An image forming apparatus characterized in that: 2) The apparatus according to claim 1, wherein the drive means is a drive motor and a drive shaft that is driven by the drive motor and transmits drive force to two or more image carriers simultaneously. 3) The apparatus according to claim 1 or 2, wherein the moving means is a transfer material conveying means for conveying a transfer material for transferring the image formed on the image carrier. 4) The apparatus according to claim 1 or 2, wherein the moving means is a transfer material for transferring the image formed on the image carrier. 5) The apparatus according to claim 4, wherein the transfer material is an intermediate transfer body. 6) The apparatus according to claim 4, wherein the transfer material is a continuously supplied roll paper.