JPH0456878A - Color image forming device - Google Patents

Abstract

PURPOSE:To reduce image memory without lowering processing ability by installing a multiple number of image exposure means at a spacing greater than the size of the recorded image and by carrying out image exposure responding to an image data for every color. CONSTITUTION:Four pieces of scorotron electrifying devices 110, 210, 310, and 410, four pieces of image exposure means, which are image exposure devices 120, 220, 320, and 420, and four pieces of developing devices, which are developing devices 130, 230, 330, and 430 are positioned facing a photosensitive body belt 1 in the backside. Then, the electrifying devices, the image exposure devices, and the developing devices are made into sets, and four sets of electrifying devices, image exposure devices, and developing devices 110, 120, 130; 210, 220, 230; 310, 320, 330; and 410, 420, 430 are located in the vicinity of each other as four sets of image forming means in a set state, faced to the photosensitive body belt 1. Thus, the expensive image storing device of a large capacity becomes unnecessary, and furthermore, high speed copying process can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a color image in which a toner image is formed on a belt-like image carrier by electrophotography and transferred onto a transfer material to obtain an image. The present invention relates to a forming apparatus, and particularly relates to a color image forming apparatus in which a plurality of image exposing means and a plurality of developing means are disposed at the peripheral portion of an image carrier.

[Background of the invention]

There are many ways to obtain color images using electrophotography.
A device has been proposed. For example, Japanese Patent Publication No. 61100770
As disclosed in the publication, a latent image is formed and developed on a photosensitive drum, which is an image carrier, according to the number of separated colors of the original image, and is transferred onto a transfer drum each time it is developed. There is a method of forming a multicolor image and then transferring it onto recording paper to obtain a color copy. A device using this method requires a transfer drum large enough to transfer one sheet of image onto its circumferential surface in addition to the photoreceptor drum, and the device does not have a large and complicated structure. Inevitable.

For example, as disclosed in Japanese Patent Laid-Open No. 61-149972, a latent image is formed and developed on a photoreceptor drum according to the number of separated colors of the original image, and is transferred onto a transfer material each time it is developed. This is a method of obtaining multicolor copies. With this method, it is difficult to overlap multicolor images with high precision, and high quality color toner cannot be produced.

Another method is to repeatedly form a latent image on a photoreceptor drum according to the number of separated colors of an original image and develop it with color toner, and then overlap the color toner images on the photoreceptor drum and transfer the images to obtain a color image. The basic process of forming a multicolor image is disclosed in Japanese Patent Application Laid-open No. 60-75850 and No. 60-7 by the present applicant.
No. 6766, No. 60-95456, No. 60-9545
No. 8, No. 60-158475, etc.

In order to form a multicolor image in which a color image is obtained by such superimposition, a plurality of developing devices containing different colored toners are arranged around the periphery of the photoreceptor drum, and generally The photoreceptor drum is rotated multiple times to develop the latent image on the photoreceptor drum to obtain a color image.

Regarding image forming bodies, as explained above, there are photosensitive drums in which a photoconductor is coated or deposited on the drum circumference, as well as belt-shaped image forming bodies in which a photoconductor is coated or mounted on a visible belt. Proposed. The shape of the belt-shaped image forming body (hereinafter also referred to as photoconductor heald) is determined by stretching it between rotating rollers including a drive roller, so it is possible to effectively utilize space and create a compact color image forming apparatus. It is effective when configured.

[Purpose of the invention]

In a color image forming apparatus using a photoreceptor belt, charging means, image exposure means,
An image forming means such as a developing means consisting of a plurality of groups of developing devices is provided, and the second image forming means faces the rotating photoreceptor belt with a certain gap therebetween.

However, a set of charging means, image exposure means, and a plurality of developing device groups are arranged around the peripheral edge of the photoreceptor belt, and thus the photoreceptor belt must rotate many times in order to obtain a multicolor image. , it takes a considerable amount of time to obtain one image.

In addition, in the above-mentioned image forming process, it is necessary to set the timing of charging and developing operations independently, which leads to problems such as increased power supply size, larger drive size, and more complicated control, which leads to increased costs. be.

In order to improve this point, a plurality of sets of charging means, image exposure means, and developing means corresponding to each single color are arranged in series on the peripheral edge of the photoreceptor belt, and during one rotation period of the photoreceptor heald, 2. Description of the Related Art Color image forming apparatuses have been proposed that obtain full-color images that can be processed at high speed by superimposing monochrome images.

However, this method requires a large-capacity image storage device because the color image signals obtained by one scan of the original by the image reading device are output in accordance with the timing of image exposure of each monochrome image.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a color image forming apparatus that reduces image memory without reducing processing performance.

[Structure of the invention]

The above object is to provide a color image forming apparatus in which at least a plurality of image exposure means and a plurality of development means are provided at the peripheral portion of an image carrier, and a toner image is superimposed on the image carrier, in which the plurality of image exposure means are provided. This is achieved by a color image forming apparatus that is arranged at intervals equal to or larger than the recorded image size and simultaneously performs image exposure corresponding to image data for each color.

Here, it is a preferable embodiment that the image exposure by the image exposure means is performed in synchronization with the reading and scanning of the document.

〔Example〕

An embodiment of the color image forming apparatus of the present invention is shown in FIGS. 1 to 3.

In FIG. 1, ■ is a flexible photoreceptor belt that is a belt-like image carrier, and the photoreceptor belt 1 is installed between rotating rollers 2 and 3, and is driven clockwise by rotating roller 2. transported to.

Reference numeral 4 denotes a guide member fixed to the main body of the apparatus so as to be inscribed in the photoreceptor belt 1, and the photoreceptor belt 1 is brought into tension by an upward mechanical action of the tension roller 5, so that its inner circumferential surface is rubbed against the guide member 4.

Therefore, the photoreceptor on the outer circumferential surface of the photoreceptor belt l is always maintained at a constant position relative to the surface of the kite member 4 during conveyance, and a stable image forming surface with a large curvature is formed with a long width. It is possible. Therefore, a large number of image forming means having the same shape can be arranged in parallel. In FIG. 1, four Sufrotron chargers 110, 21 are located opposite the photoreceptor belt l with the guide member 4 behind it.
0,310°410, four image exposing devices 120,220°320,420 as image exposing means, and developing devices 130,230°330,430 as four developing means. Then, the charger, image exposure device, and developer are combined into 4
Charger, image exposure device, developer 110, 120, 13
0; 210.220.230; 310,320
410, 420, and 430 are adjacent to each other as a set of four image forming means, and are opposed to the photoreceptor bell l-1. Since each charging device and each developing device are arranged close to each other in substantially parallel, it is possible to use a common power source and drive.

Image exposure device 120.2 of each of the four sets of image forming means described above
20.320.420 is an interval larger than the recorded image size, such as A4 size suspension (210mm x 297mm).
They are arranged at equal intervals with intervals slightly exceeding the image width (210 mm) when the recording paper is fed horizontally.

Reference numeral 6 denotes a cleaning device, and a built-in blade 6A and a toner conveying roller 6B are supported so as to be able to be brought into and out of pressure contact with the photoreceptor belt 1.

Reference numeral 10 denotes a document image reading device that sends image signals to each of the image exposure devices, which includes movable scanning units 11 and 12, an imaging lens 13, and a color CCD 1 that is an image pickup device.
It consists of 4.

The scanning unit 11 includes an exposure lamp IIA and a second reflecting mirror 12A, while the scanning unit 1-12 is arranged at right angles, and includes a second reflecting mirror 12A and a third reflecting mirror 12B, as shown by the arrow. a predetermined velocity V in each direction
and moves at a speed of V/2, and scans the image of the document onto the color CCDI 4 through the imaging lens 13.
project.

The reading device 10 reads yellow (
Y), magenta (M), cyan (C) and black (BK)
A color signal for each color is output and input to the image exposure device.

In the image exposure device, the color signal is generated by a semiconductor laser to generate a laser beam, which is rotated and scanned by a polygon mirror, passes through an fθ lens, and is projected as a bright line onto the charged photoreceptor belt l through the image exposure device. Even if it is a laser writing system unit that forms an electrostatic latent image corresponding to the color signal, as shown in the figure, it is also possible to use a laser writing unit that forms an electrostatic latent image corresponding to the color signal. The image exposure optical system may be integrated with a light emitting section such as an LED that emits light based on a signal.

The electrostatic latent image formed based on this color signal is reversely developed by a developing device provided in each image forming means, and is then developed with yellow (Y), magenta (M), cyan (C), or black (BK) toner, respectively. It is considered an image.

Therefore, by driving each of the image forming means in synchronization with the reading and scanning of the original image, it is possible to sequentially form color toner images on the belt facing each of the image forming means. By performing imagewise exposure in accordance with the interval between the means and the conveying speed of the photoreceptor belt, it is possible to sequentially superimpose the toner images for each color.

The specific image flow by the image forming apparatus of the present invention is as follows:
The processing is performed according to the process mode described below depending on the image size and the number of copies. Here, the image exposure devices 120, 220320, and 420 are arranged at regular intervals with intervals exceeding the image size, here A4 size.

Figures 2 and 3 show the timing of image exposure for each color, which is synchronized with the number of scans of original reading in accordance with the copy size. Figure 2 (a) shows an image of A4 size or smaller. This figure shows a process mode for continuous copying of 4 sheets. When copying 4 sheets of A4 size, the reading device 10 outputs a yellow (Y) color signal in the first reading scan as shown in FIG. A latent image is formed on the synchronously rotating photoreceptor belt l by the exposure scanning of the image exposure device 120, and reversal development is performed by the developing device 130 to which a direct current and an alternating current developing bias is applied.
Only the toner image of Y) is formed.

Then, in the second reading scan, yellow (Y) and magenta (
M) outputs two color signals, each with a charger 110°21
Following the uniform charging of the photoreceptor belt l by 0, a yellow (Y) latent image is formed by the image exposure device 120 and the developing device 1
A new yellow (Y) toner image is formed by reversal development at step 30, and at the same time, a yellow (Y) z-image formed by the first scan is formed by the exposure strip of the image exposure device 220 and reversal development by the developing device 230. Magenta (
M) toner images are formed and superimposed.

Yellow (Y) synchronizes with the third and fourth reading scans.
), magenta (M), cyan (C) and yellow
(Y), magenta (M), cyan (C), black (BK)
The number of superimposed toner images is increased sequentially, and after reaching the fifth time, magenta (M) and cyan (C) are
, black (BK), 7th An (C) in the sixth time, and black (BK), thereby completing seven reading scans and seven rotations of the photoreceptor belt 1. At this stage, the four full-color toner images are successively transferred onto recording paper, fixed, and then ejected from the apparatus as a copy.

That is, the recording paper is continuously carried out one by one from the paper feed cassette 21 by the carry-out roller 22, and the timing roller 2
3, yellow (Y), magenta (M), cyan (C), and black (BK) toner images are sent to the transfer device 24 in synchronization with the superimposed toner image and are continuously transferred.

The recording paper that has undergone the transfer has toner fused thereon in a fixing device 25, and is then discharged to the outside of the apparatus via a paper discharge roller 26.

On the other hand, after the transfer, the photoreceptor belt 1 is moved to the cleaning device 6 in which the blade 6A and the toner conveying roller 6B are brought into pressure contact to remove and clean the remaining toner, and then move on to the next image forming cycle.

Therefore, in the embodiment shown in FIG. 2(a), since the color signals read by the reading device 10 are output to the writing device each time, an image storage device is not required, and furthermore, the photoreceptor belt 1 Since a plurality of toner images can be continuously formed on the circumferential surface of the printer, the copying speed for continuous copying of a large number of sheets can be increased.

FIG. 2(b) shows a process mode when only one image of A4 size or smaller is to be copied. Each rotation of the photoreceptor belt, which rotates in synchronization with the number of reading scans, sequentially prints toner images of each color (yellow (Y) at the first time).
, Magenta (M) for the second time.

The third time, cyan (C) and the fourth time, black (BK) are formed and superimposed, and a full-color toner image is obtained by four reading scans. At the stage where the toner images made of black toner are superimposed by the fourth rotation of the photoreceptor belt, a full-color image is transferred onto a sheet of recording paper, fixed, and then discharged. In the process mode of this embodiment, an image storage device is not required since the read color signals are output to the writing device each time.

Although charging and development are activated and stopped in each step, they can also be kept in constant operation during image formation.

Figure 3 shows the process mode when recording images of A3 size suspension.
It is figure (a). The image exposure gap for yellow and cyan is A3.
It is set wider than the size. The reading device IO outputs a yellow (Y) color signal in the first reading scan, performs yellow (Y) image exposure and yellow (Y) development, and then, at a predetermined timing, performs the second reading scan. Two color signals of yellow (Y) and cyan (C) are outputted, and yellow (Y) and V-an (C) images are formed. At this time, the timing is set so that the cyan (C) image overlaps with the yellow (Y) image. Furthermore, with a predetermined timing 3
In the second reading scan, a cyan (C) color signal is output to form a cyan (C) image, and yellow (Y) and cyan (C) are formed.
Two toner images are formed by overlapping each other on the photoreceptor bell l-1.

Similarly, on the second rotation of the photoreceptor belt 1, a magenta (M) toner image is further superimposed on the first toner image, and a fifth magenta (~1) and black (B) toner image is superimposed on the first toner image.
K) toner image is superimposed on the second and first toner images, and when the black (BK) toner image is superimposed on the second toner image in the sixth reading scan, the second toner image is Get a full color tona image. Subsequently, the image is transferred and fixed onto the recording paper that is conveyed synchronously.

Figure 3(a) shows the process mode when copying two A3-size sheets; as is clear from this, full-color images can be obtained by the two-rotation method of the photoreceptor belt 1 during continuous copying. .

Further, the process mode when copying only one A3 size image is as shown in FIG. 3(b). The first reading scan produces a yellow (Y) color signal, and the second reading scan at a predetermined timing produces a cyan (C) color signal.
) to form one toner image in which yellow (Y) and cyan (C) are superimposed during one rotation of the photoreceptor belt 1.

During the second rotation of the photoreceptor belt l, magenta (M) and black (BK) toner images are further superimposed on the above-mentioned toner image, thereby performing 4 rotations in synchronization with the two rotations of the photoreceptor belt l. One full-color toner image is obtained by multiple reading scans. However, in this process mode, the fourth reading scan following the third reading scan is started after the second rotation of the photosensitive belt reaches the writing position.

Furthermore, in the process modes shown in Figures 3(a) and (b), compared to the process cartridges shown in Figures 2(a) and (b), yellow (Y), cyan (C), magenta (M), black (BK) is formed in different order, and with the same color correction, there is a tendency for the cyan color to be stronger and the magenta color to be weaker. Therefore, in the color correction processing section, the image signal is corrected to weaken the cyan color and strengthen the magenta color. When overlapping toner images in the normal order of yellow (Y), magenta (M), cyan (C), and black (BK), the photoreceptor belt It is also possible to perform one reading scan in the above-mentioned color order for each rotation of the image sensor 1, and to sequentially overlay the toner images formed thereby to form a full-color toner image.

In this embodiment, the number of continuous copies is set to 4 or 2, but in the process mode of the color image forming apparatus of the present invention, it is naturally possible to make continuous copies of a larger number of copies. By increasing the number of sheets, copying efficiency can be improved.

〔Effect of the invention〕

According to the present invention, image signals for each color obtained by reading and scanning a document are input directly to a writing device and individually outputted to an image exposure device, thereby forming image signals for each color on an image carrier synchronized with the reading and scanning. Achieves the formation and superimposition of toner images.
As a result, an extremely useful color image forming apparatus that eliminates the need for an expensive, large-capacity image storage device and also enables high-speed copy processing has been provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus of the present invention, and FIGS. 2 and 3 show process modes of the present invention. A chart diagram showing timing relationships.

Claims (2)

[Claims] (1) In a color image forming apparatus in which at least a plurality of image exposure means and a plurality of development means are provided at a peripheral portion of an image carrier, and a toner image is superimposed on the image carrier, the plurality of image exposure means record recording. A color image forming apparatus characterized in that the apparatus is arranged at intervals equal to or larger than the image size and simultaneously performs image exposure corresponding to image data of each color. (2) The color image forming apparatus according to claim 1, wherein the image exposure by the image exposure means is performed in synchronization with reading and scanning of the original.