JPS63249165A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image excellent in quality free from damage even in the non-full color mode by stopping the operation of only transfer means in image forming parts other than the image forming part where the transfer process is performed. CONSTITUTION:In the non-full color mode, the operation of only an transfer charger 6b out of image forming means, namely, photosensitive drums 1B, 1C, 1M, and 1Y, electrifiers 2B, 2C, 2M, and 2Y, optical scanning means 3, developing devices 4B, 4C, 4M, and 4Y, and the transfer charger 6b in image forming stations of colors other than a desired color, and the other process devices are operated in the same manner as the normal full color mode. Then, the image is not affected by rubbing at the time of passing image forming stations of colors other than the desired color and the toner on a transfer material is not transferred to the photosensitive body side again. Further, the developer is not transferred from an image carrier to a transfer material. Thus, the image superior in quality is obtained in the simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an image forming apparatus;
In particular, by arranging a plurality of image carriers such as electrophotographic photoreceptors,
These photoreceptors are subjected to an electrophotographic image forming process to obtain developed images of multiple images or multiple colors, and the developed images are transferred to a transfer material carried and conveyed by a transfer material conveying device, an intermediate transfer body, or a continuous paper. This invention relates to a multiplex (multicolor) electrophotographic image forming apparatus that sequentially transfers images onto an image receptor using an electrostatic transfer means to obtain multiple images or color images. (1) It can be embodied in various printers, facsimile machines, etc.; (1) In this specification, a color electrophotographic system is used in which a plurality of light scanning means are arranged to scan a light beam from a light source and irradiate image information onto an image carrier. This will be explained in relation to a laser beam printer. 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. .

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Conventionally, several methods have been proposed as electrophotographic laser beam color printers. Laser beam printers with multiple optical scanning means include a laser device as a light source and a rotating polygon mirror that scans the laser device. , an fθ lens that focuses the scanning beam onto the generatrix of the photosensitive drum surface, and a reflecting mirror that deflects the light beam.
and a beam detection device that detects a specific position of the scanning beam.

An example of a laser beam printer having a plurality of such light scanning means is shown in FIG. The image forming means, that is, the charger 2, the optical scanning means 3, the image forming device 4. A cleaner 5 is provided. An image forming section including the photosensitive drum 1, charger 2, optical scanning means 3, developing device 4, and cleaner 5 is arranged for each color station of yellow, magenta, cyan, and black. Further, the transfer unit 6 as a moving body has a transfer bell) 6a, an electrostatic transfer means, for example, a transfer charger 6b, and the formation of a full color image is performed by sequentially applying colors onto a transfer material supported on a transfer belt Sa. It is formed by transferring toner. This transfer material is supplied from a paper feed cassette 7, and the transfer material that has completed the transfer process is separated and delivered onto a tray 9 via a fixing device 8.

In a four-drum full-color printer with the above configuration, for example, in the case of monochrome mode, the transfer material supported on the transfer bell 6a passes sequentially to the yellow station, magenta station, cyan station, and black station. The image forming section includes a desired station, for example, a yellow station image forming section, that is, a photosensitive drum 1, a charger 2, an optical scanning means 3, and a developing device 4.
, Cleaner 5, electrification for transfer! 16b is in operation.However, as mentioned above, the transfer material is sequentially sent to the yellow, magenta, cyan, and black stations and passes through the gap between the transfer belt and the photosensitive drum.
If all operations in the image forming process at the undesired station, in this case the magenta, cyan, and black stations, are stopped, the transfer material will be transferred as it passes through the gap between the drum and belt of each station other than yellow, as described above. The image already formed on the material is magenta,
A problem arises in that the two images are significantly damaged by rubbing by the cyan and black photosensitive drums.

Also, the yellow toner transferred onto the transfer material at this time is electrostatically attracted onto the transfer material, so the transfer material passes through the gaps between the magenta, cyan, and black photosensitive drums and the belt. At this time, if these photosensitive drums are electrostatically charged with a polarity different from that of the yellow toner forming the yellow image, the yellow toner on the yellow image will be attracted onto the photosensitive drum. This also causes the problem that the image deteriorates significantly.

Furthermore, in such a case, clogging of the transfer material (hereinafter referred to as jam) is likely to occur when the transfer material passes through the gap between the drum and the belt.

7 and 8 show a second conventional example proposed to improve image abrasion in monochrome mode. In the conventional example, yellow, magenta, cyan, and black photoreceptor dots 1 A backup member 10 is arranged near the transfer charger 6b for each. Each backup member 10 is
A lever 12 rotatably indicated by a fulcrum 11, a roller 13 rotatably supported at the end of the lever 12 on the side of the transfer belt 6a, and the roller 13 is pressed against the transfer belt 6a, and the transfer belt ) 8a against the photosensitive drum, a pressing member 14 such as a solenoid, and a spring 15 that applies a force to move the lever 12 to the standby position.

With this configuration, in a single color mode, for example, a yellow single color mode, the yellow backup member 10Y is mirror operated as shown in FIG. In other words, by applying the pressure member 14 of the yellow station,
The transfer belt 6a contacts only the photosensitive drum IY, and the other photosensitive drums 1M, IC, and IBK do not come into contact with the transfer belt, so that the above-described problem of image abrasion does not occur.

As described above, in the second conventional example, the transfer belt can be removed from and pressed against the photosensitive drum of an undesired image forming station, so the problem of image rubbing is solved; A pressure release mechanism for the photosensitive drum is required for each station, and the pressure between the backup member and the photosensitive drum tends to cause transfer unevenness and transfer defects during image transfer, so this method is not completely satisfactory. do not have.

In order to solve the above-mentioned problems, the present inventors proposed an image forming apparatus characterized in that only the developing device is stopped in operation in an image forming section other than the image forming section currently performing the transfer process. did. Although this device has a simple structure and can provide the advantages of solving the problem of image abrasion and obtaining good quality images without image damage, for example, after transfer, In an image forming apparatus that employs a blade cleaning method in which a blade-shaped member is pressed against the image carrier to scrape off the residual developer on the image carrier in order to collect the residual developer on the image carrier, Since the blade is pressed against the image carrier at an acute angle, if no developer remains on the image carrier, the coefficient of friction between the blade and the image carrier increases, and as a result, the cleaning blade The present invention relates to an improvement of such an image forming apparatus.

An object of the present invention is to solve the problem of rubbing of one image even in a single color mode or a non-full color mode such as two colors or three colors, and to obtain a good quality image without image damage. An object of the present invention is to provide an image forming apparatus.

Another object of the present invention is to provide a low-cost image forming apparatus that has a simple structure and does not cause deterioration of a single image or jam of a transfer material.

Another object of the present invention is to provide an image forming apparatus that does not cause "blade turning" of the cleaning blade.

Still another object of the present invention is to provide a multicolor image forming apparatus that can satisfactorily form multicolor and monochrome images.

The above aspects are achieved by the image forming apparatus according to the present invention. To summarize, the present invention forms a latent image on an image carrier with an image forming means, and develops the latent image with a developing device to form a visible image. In an image forming apparatus in which an image formed on a section is sequentially transferred by a transfer means to a moving body passing through the transfer position of each image forming section, an image formed on an image forming section other than the image forming section currently performing the transfer process is The image forming apparatus is characterized in that in the forming section, only the transfer means is stopped from operating.

Practical JL Example Next, an image forming apparatus according to the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a four-drum full-color printer similar to that described in connection with FIG. It has four color stations,
The image forming section of each station includes electrophotographic photosensitive drums IY, IM, IC, and IB as image carriers, and image forming means arranged around them, that is, chargers 2Y, 2M, and 2C.
12B, optical scanning means 3Y, 3M, 3C1SR.

Developing units 4Y, 4M, 4C, 4B, cleaner 5Y.

5M, 5G, and 5B are installed.

Furthermore, in this embodiment, the moving body located at the transfer section is a transfer belt 6a, which supports the transfer material supplied from the paper feed cassette 7 on the mirror transfer belt 6a, and sequentially transfers the transfer material to the transfer section of each station. An electrostatic transfer means 6 such as a transfer charger
An image is formed on the transfer material by transferring the color toner onto the transfer material under the action of b. The transfer material that has completed the transfer process is separated and reaches onto the tray 9 via the fixing device 8.

According to one aspect of the present invention in the above configuration, when in a non-full color mode such as a single color mode, two color mode, or three color mode, that is, when the four colors of yellow, magenta, cyan, and black are not used, the desired color is Image forming means in the external image forming station, ie, photosensitive drum 1, charger 2, optical scanning means 3. Developing device 4. Of the transfer chargers 6b, only the operation of the transfer charger 6b is stopped, and the other process devices are operated as in the normal full color mode.

At this time, the transfer charger 6b is a transfer means configured to apply a corona discharge with a polarity opposite to that of the toner particles, and in this embodiment, a corona charger as shown in FIG. 1 is used. , other transfer means can be used as long as they satisfy the above-mentioned requirements.

Next, 1. For example, taking the yellow single color mode as an example, the above at
The operation of the image forming apparatus will be explained below.

Now, since the apparatus is in the yellow single color mode, the transfer means in the image forming sections of each station for magenta, cyan, and black, that is, in this embodiment, the process equipment other than the transfer charger 6b is operated in the same way as in the normal full color mode. All image forming means are operating normally at the yellow station. The transfer material supplied from the paper feed cassette 7 first passes through a yellow station, where a yellow image is formed by a normal image forming process. After that, the photosensitive drum IM of the magenta station passes between the photosensitive drum IM and the transfer bell) 6a, but at this time, the photosensitive drum LM, the charger 2M, the optical scanning means 3M, and the developing device 4 are in operation at the magenta station. Since the transfer charger 6b is stopped, a small amount of developer adheres to the photosensitive drum 1M, causing "blade turning" in the cleaning blade.
phenomenon is completely resolved. Moreover, according to the present invention,
Since the operation of the transfer charger 6b is stopped, a small amount of developer particles adhering to the photosensitive drum will not become "fog" and be attracted to the transfer material, thereby reducing the quality of the image. There isn't.

To explain further, when the transfer material on which an image has been formed at the yellow station passes through the gap between the photosensitive drum and the conveyor belt at the magenta station, even if a latent image is formed at the magenta station and the transfer material is developed at the magenta station. When the latent image is developed in the magenta station, developer particles are attached to the surface of the photosensitive drum, but the transfer material on which the yellow image has already been formed passes through the gap between the photosensitive drum and the conveyor belt of the magenta station. However, the toner particles on the photosensitive drum continue to the cleaning device on the photosensitive drum.
Also, the yellow toner image on the photosensitive drum is not transferred to the photosensitive drum because it is attracted to the transfer material, and since the photosensitive drum is rotating together with the conveyor belt, the image on the transfer material is The image will not be damaged by rubbing against the photosensitive drum, or jams will not occur in the gap, and even if a latent image is not formed by the light operating means, the developing device will not operate. Since a small amount of developer adheres to the photosensitive drum and circulates, "blade turning" of the cleaning blade can be prevented.

Thereafter, when passing through the cyan and black stations, the transfer material that has completed the transfer process without damaging the yellow image formed on the transfer material is separated and transferred to the tray 9 via the fixing device 8 in the same way as when passing through the magenta station. leading to.

In the two-color mode and the three-color mode, it is possible to obtain an image of good quality without disturbing the image on the transfer material, as in the case of the single-color mode.

Figures 2 and 3 show the operating status of each process device.
FIG. 2 shows the normal operating state of each process device during full-color image formation and the operating state of each process device at a desired color station during monochromatic color mode, and FIG.
3 illustrates the operating status of each process device in a monochromatic color mode or a non-full color temporary imaging station other than the desired one;

In the above embodiment, the movable body is a transfer material conveying means 6a such as a transfer belt that conveys a transfer material P for transferring an image formed on an image carrier, but the movable body is shown in FIG. It is also possible to use an intermediate transfer body 16 for transferring an image formed on an image carrier as shown in FIG. or,
As shown in FIG. 5, the moving body is a continuously supplied roll paper 17, that is, a transfer material P, and the image on the photosensitive drum is transferred onto the roll paper.

The image forming apparatus according to the present invention has the above-described configuration and operation, and can achieve the following effects.

(1) In monochrome mode or non-full color mode, there is no influence on the image due to rubbing of the image when it passes through the image forming station of a color other than the desired color.

(2) There is no paper jam of the transfer material when it passes through the image forming station of a color other than the desired color in the single color mode or non-full color mode.

(3) Toner on a transfer material passing through an image forming station of a color other than a desired color in a single color mode or a non-full color mode is not retransferred to the photoreceptor side.

(4) There is no transfer of developer from the image carrier onto the transfer agent when passing through an undesired image forming station in monochrome mode or non-full color mode.

(5) It is possible to prevent "blade flipping" of a cleaning blade used in an undesired image forming station in a single color mode or a non-full color mode.

It is possible to obtain an image of excellent quality with a simple structure while alleviating various effects such as the following.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view of an embodiment of an image forming apparatus according to the present invention. FIGS. 2 and 3 are timing charts showing the operating mode of the image forming apparatus according to the present invention. FIGS. 4 and 5 are schematic longitudinal sectional views of another embodiment of the image forming apparatus according to the present invention. FIG. 6, FIG. 7, and FIG. 8 are schematic longitudinal sectional views of a conventional multicolor image forming apparatus. IY, LM, IC, IB: Image carrier 2Y, 2M, 2C, 2B = Charger 3Y, 3M, 3C13B: Optical scanning means 4Y, 4M, 4C14B: Developing device 5Y, 5M, 5C15B = Cleaner 6: Transfer section 6a : Transfer material conveyance means 16: Intermediate transfer body 17 2nd roll paper OFF □ Fig. 4 Fig. 5

Claims (1)

[Scope of Claims] 1) A plurality of image forming sections are arranged side by side for forming a latent image on an image carrier by an image forming means and developing the latent image by a developing device to form a visible image, and each of the images In an image forming apparatus in which an image formed in a forming part is sequentially transferred by a transfer means to a moving body passing through the transfer position of each image forming part, an image forming part other than the image forming part currently performing the transfer process is used. An image forming apparatus characterized in that in the image forming section, only the transfer means is stopped from operating. 2) The image forming apparatus according to claim 1, wherein the movable body is a transfer material conveying means for conveying a transfer material for transferring the image formed on the image carrier. 3) The image forming apparatus according to claim 1, wherein the moving body is a transfer material for transferring the image formed on the image carrier. 4) The image forming apparatus according to claim 3, wherein the transfer material is an intermediate transfer body. 5) The image forming apparatus according to claim 4, wherein the transfer material is a roll paper that is continuously supplied.