JPH0348593Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a color electrophotography system that performs color copying using a full-surface exposure method that exposes the entire image on a belt-shaped photoreceptor (hereinafter referred to as a photoreceptor belt). Regarding equipment.

[Conventional technology]

In recent years, various color electrophotographic apparatuses have been proposed that are capable of color copying a desired image onto plain paper (hereinafter referred to as transfer paper).

By the way, regarding this color electrophotographic device,
Normally, when making color copies, the original image is separated into three color images: yellow, magenta, and cyan.
These images are exposed and projected each time onto a photosensitive belt to form a latent image, and this latent image is developed and transferred and fixed onto a transfer paper. In other words, the above series of steps is repeated three times using each color toner (hereinafter referred to as color toner) for each image, thereby transferring and fixing the three types of color toners onto the transfer paper. It is composed of For this reason, when performing color copying, the copying time is significantly longer than when performing normal black and white copying.

Therefore, in order to shorten copying time, a so-called full-exposure type color electrophotographic apparatus has been proposed, in which the entire image is exposed and projected onto a photoreceptor belt for copying. There is.

[Problem to be solved]

However, in the case of the above-mentioned type of color electrophotographic apparatus, although the exposure time is shortened, the series of steps from charging to post-fixing cleaning and neutralization still requires three steps.
Since the process is repeated several times, the copying time is quite long. In particular, images on a CRT screen (hereinafter referred to as CRT images) when connected to a video device, etc.
When copying images, the image itself is dark, so in order to secure the minimum amount of light necessary to form a latent image, a relatively long exposure time of one to several seconds is necessary. It has the disadvantage that the copying time is longer.

Additionally, this type of color electrophotographic equipment usually has
As shown in Figure 4, a loop-shaped conveyance path b is installed to transfer and fix three-color toner onto the transfer paper a, and the device becomes larger to accommodate this loop-shaped conveyance path b. It also has the disadvantage of

The purpose of this invention is to eliminate the above-mentioned drawbacks of conventional color electrophotographic devices, and more specifically, to provide a compact color electrophotographic device that takes less time to copy. It's about doing.

[Means for solving problems]

That is, this invention includes first to third developing devices that develop by adsorbing the first to third toners on the photosensitive belt after forming the latent image, and
In a color electrophotographic apparatus that performs color copying by full-surface exposure, the color electrophotographic apparatus includes a fixing device for fixing toner of a third color to a transfer paper, etc.;
A reciprocating means for conveying and returning the transfer paper after toner fixation to the original position is disposed near the fixing device, and immediately after the third and final exposure is completed, the first to third developing These first to third developing devices are arranged at a constant distance from the exposure area so that the devices operate sequentially with some overlap in time, and the first to third latent images are placed on the photoreceptor belt. The first to third developing devices are disposed at a minimum allowable distance from the exposure area so that the first to third developing devices are formed close to each other while maintaining the necessary minimum gap above, and the first to third developing devices are arranged at a minimum allowable distance from the exposure area. The developing devices operate while partially overlapping each other, and the transfer paper is moved back and forth over the minimum necessary distance by the moving means so that the first to third color toners can be continuously transferred and fixed. Because it is moved, a series of processes that used to be performed three times for each of the first to third latent images can be performed at once, and a long loop-shaped conveyance path is no longer required, which greatly reduces copying time. , and the device can be made smaller.

〔Example〕

An embodiment of this invention will be described with reference to the accompanying drawings.

FIG. 1 shows a color electrophotographic device according to this invention, and this color electrophotographic device has the following features:
A CRT image of a video device not shown is transferred to the photosensitive belt 1.
An optical system 2 that exposes and projects light onto the photosensitive belt 1
In order to visualize the latent image formed on the top, yellow, magenta, and cyan color toners (first to third
first to third developing devices 3 containing color toner);
4 and 5, a transfer device 7 for transferring the colored toners adsorbed onto the photosensitive belt 1 onto the transfer paper 6, and fixing the colored toners on the transfer paper 6 immediately after each transfer of the colored toners to the transfer paper 6, respectively. It is composed of a fixing device 8, a reciprocating device 9, and the like. This color electrophotographic apparatus is also equipped with a developing device 10 containing black toner in addition to color toner to enable normal black-and-white copying.

The optical system 2 is for temporarily stopping the rotation of the photosensitive belt 1 and projecting the entire CRT image onto the photosensitive belt 1, and is provided with a projection lens L and the like. When performing color copying, images corresponding to each color are continuously projected onto the photoreceptor belt 1 at fixed time intervals, and the images are placed adjacent to each other on the photoreceptor belt 1.
It is configured to form three types of latent images (first to third latent images) that are close to each other.

The first to third developing devices 3, 4, and 5 perform yellow, magenta, and cyan color development (first to third development), respectively. .
1, 12, and 13 can move forward and backward. By the way, the first developing device 3 is designed so that the leading edge side of the first latent image initially formed on the photosensitive belt 1 does not enter the developing process of the first developing device 3 before the third exposure is completed. That is, in FIG. 2, with respect to the length l of the maximum latent image area, the distance S ₁ between the tip A of the first exposure area and the setting position B of the developing roll 11 is S ₁ > 2 (l + △X), (However, , Δx is the length of the gap between each latent image area). Further, the distance _{S 2} between the first developing roll 11 and the second developing roll 12 is such that the second developing device 4 operates t seconds after the start time of the first developing device 4 . vt (where v is the circumferential speed of the photosensitive belt 1). Similarly, the third developing device 5 is set so that it starts operating _{t seconds} after the operation start time of the second developing device 4. (distance between

The transfer device 7 is installed at a portion of the photoreceptor belt 1 facing the drive roll 14, which has a large curvature, so that the transfer efficiency is increased and the photoreceptor belt 1 easily peels off the transfer paper 6 onto which the color toner has been transferred. ing.

The fixing device 8 is provided near the transfer device 7 in order to fix the first to third color toners transferred to the transfer paper 6 immediately after the transfer, and in this embodiment, , it is composed of a heat roll 15 and a pressure roll 16 that are in pressure contact with each other. These heat rolls 15 and pressure rolls 16 pass between these rolls 15 and 16, when the transfer paper 6 adsorbing the toner of each color passes between these rolls 15 and 16.
The toner of that color is melted by heat and transferred to transfer paper 6.
It is becoming more and more established.

After the first color toner is fixed and the second color toner is fixed, the reciprocating means 9 returns the transfer paper 6 to the front position of the transfer device 7 in order to transfer and fix the next color toner onto the transfer paper 6. In this embodiment, rotating rolls 17 and 18 that rotate in forward and reverse directions are provided near the fixing device 8 and the transfer device 7 in order to reciprocate by the minimum necessary distance d. Note that the rotating roll 18 near the transfer device 7 also functions as a registration roll for aligning the transfer paper 6 and the developed latent image area. The transfer paper 6 is reciprocated two and a half times by these rotating rolls 17 and 18, and transfer and fixing are performed three times each by the transfer device 7 and the fixing device 8.

Although this embodiment is configured to copy a CRT image, the invention is of course not limited to this; for example, it may be used to copy a document placed on a platen glass. It can also be applied to ordinary types such as

Next, the operations of the first to third developing devices will be explained using FIG.

After the images of each color are successively exposed and projected three times on the photosensitive belt 1, the first latent image area α on the photosensitive belt 1 is formed by exposing and projecting the image of the first color, that is, yellow. When the leading end reaches the vicinity of the first developing device 3 as the photosensitive belt 1 rotates, the developing roll 11 in the first developing device 3 advances toward the photosensitive belt 1. After t seconds have elapsed, the leading end of the second latent image area β corresponding to the second color, that is, magenta, reaches the vicinity of the second developing device 4, and the developing roll 12 advances toward the photosensitive belt 1. After another t seconds have elapsed, the leading end of the third latent image area γ corresponding to the third color, that is, cyan, reaches the vicinity of the third developing device 5, and the developing roll 13 moves forward in the same manner.

After a certain period of time has elapsed, when the rear end side of the first latent image area α corresponding to yellow passes through the first developing device 3, the developing roll 11 is moved backward, and every t seconds thereafter, the developing rolls 12 and 13 are Retreat from the photosensitive belt 1. In this way, the development of the three types of color toners is completed.

Therefore, if the color electrophotographic apparatus according to this embodiment is used, a color copy can be made in a single copying process, and the copying time is significantly shortened.

Further, by using the color electrophotographic apparatus according to this embodiment, the apparatus can be made smaller because the photosensitive belt is shorter and a loop-shaped conveyance path is not required.

Furthermore, if the color electrophotographic apparatus according to this embodiment is used, the charging potential of the toner usually decreases when the toner is heated.
The color toner fixed in Step 5 has no risk of having various negative electrostatic effects on the surroundings during the next color toner transfer, and the transfer efficiency is good.

〔effect〕

As described above, when the color electrophotographic apparatus according to this invention is used, the first to third latent images are formed adjacent to and close to each other on the photosensitive belt, and the first to third latent images are formed on the first to third developing rolls. Since these are designed to operate sequentially with some overlap in time, a series of steps can be performed at once, greatly reducing copying time, especially for video equipment that requires a long exposure time. The effect is especially great when copying dark images such as those on the screen.

Furthermore, when the color electrophotographic apparatus according to this invention is used, the distance between the first to third developing devices and the exposure area is minimized, and the length of the photosensitive belt can be shortened accordingly. In addition, since a reciprocating means is provided, a loop-shaped conveyance path is not required, and the apparatus can be significantly downsized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a color electrophotographic apparatus according to this invention, FIG. 2 is an explanatory diagram showing the positional relationship between the latent image area corresponding to each color and each developing device, etc. according to this invention, The figure is a time chart showing the operating time of each developing device according to this invention, and FIG. 4 is a block diagram showing the structure of a conventional color electrophotograph. 1...Photosensitive belt, 2...Optical system, 3, 4, 5
... (first, second, third) developing device, 6 ... transfer paper, 8 ... fixing device, 9 ... reciprocating device, 1
1, 12, 13...Developing roll, α...First latent image area, β...Second latent image area, γ...Third latent image area.

Claims (1)

[Claims for Utility Model Registration] First to third developing devices that develop by adsorbing first to third color toners onto the photosensitive belt after forming a latent image, and the first to third color toners transferred to the photoreceptor belt. In a color electrophotographic apparatus that is equipped with a fixing device etc. that fixes color toners to a transfer paper and performs color copying by full exposure, the transfer paper after the first and second color toners are fixed is transported to its original position. A reciprocating means for returning to the original state is disposed near the fixing device, and the first to third developing devices are operated sequentially with some temporal overlap immediately after the third and final exposure is completed. A color electrophotographic apparatus characterized in that the first to third developing devices are arranged at a constant distance from an exposure area.