JPS59111653A - Color copying machine - Google Patents

Abstract

PURPOSE:To obtain a color copy at a high speed by projecting light beams separated by filters upon three photosensitive drums and foming toner images in three primary colors, and transferring them to running paper successively. CONSTITUTION:An image of an original 1 is projected upon the 1st photosensitive drum 13 through a blue filter 7 and the formed latent image is developed with yellow toner 16. The 1st mirror 11 is put back off an optical path 11' and the 2nd mirror 21 is placed on the optical path. Optical scanning systems 2-4 are moved back speedily to project the original image upon the 2nd photosensitive drum 23 through a green filter 8, and the formed latent image is developed with magenta toner 26. Similarly, an image of cyan toner 36 is obtained on the 3rd photosensitive drum 33 through a red filter 9. The paper 41 is run by a belt 40 to transfer the three toner images from the respective drums. Intervals of respective transfer parts 44, 45, and 46 are equal to the length of rotation of drum surfaces during the backward movement of the optical systems, so those three images are transferred so that their front edges are coincident.

Description

[Detailed description of the invention] The present invention relates to a color copying apparatus.

An example of producing multicolor copies at high speed has already been proposed in German Patent Application No. 32 06 948. This is such that the colors of the individual color separations of the document are formed simultaneously, with each color separation image being formed on its corresponding photoconductive screen belt. In that device, electrostatic latent images of individual color anatomical regions are formed into toner images on corresponding insulating belts and transferred onto passing copy paper. The insulating belt then skips in transferring the individual color toner images in the correct color record onto the copy paper that is passed by the insulating belt at a constant speed.

That is, upon arrival of the copy paper, the transfer of the toner image is jumped into position such that proper recording will occur.

This device is relatively expensive from a technical standpoint.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multicolor copying device whose structure is simple.

Even if the photoreceptor rotates further, the copy paper, which is the transfer material that passes through the gaps between the process sections for each color, is selected to take in the color-specific toner at the proper transfer position, using a special control method. Can be omitted. Each color separated image of the original is simultaneously produced on each photoreceptor by providing a transmission mirror and a corresponding color filter.

Alternatively, each color separation of the original is first exposed to light to form an electrostatic a-image of the first color separation image by rotating a fully reflecting flat mirror, and then the original is repeatedly scanned. As a result, the second photoreceptor, etc. that takes in the immediately next color separation image is exposed in the same manner, so that the color separation image is produced on each photoreceptor sequentially in time.

In the color copying apparatus according to the present invention, a problem arises in how to handle the idling distance of each photoreceptor, which occurs when a scanning element such as a mirror or document table returns to its starting position.

Examples include: Electrostatic latent images of individual color anatomy are formed on individual photoreceptors by scanning the document many times, requiring one revolution per scan, with each photoreceptor being the first to advance. Approximately 40% of its circumference
When rotated, that is, at an angle of approximately 144°, a latent image of the next color segment anatomy is created. For this purpose, before this next photoreceptor is exposed, the scanning element is moved backwards at twice and a half the scanning speed. When using a photoreceptor with a diameter of 160 m, the leading edge positions of electrostatic latent images formed by individual color separations are shifted from each other by about 200 degrees on the circumference of each photoreceptor. In this way, since the tip of the latent image for each color separation is at an image shift distance of 200 - on each photoreceptor, if the axes of these photoreceptors are separated from each other and the distance between each transfer position is set to 200 -, By passing copy paper in contact with each photoreceptor and passing through the transfer position at a constant speed,
A color image in which each color separation image is correctly superimposed can be obtained. However, the copy paper is passed through each photoreceptor after a toner image corresponding to the color separation image is formed on each photoreceptor.

In the above-mentioned apparatus, the photoreceptor on the downstream side in the traveling direction of the copy paper is rotated through 360 degrees. At this time, the copy paper has not yet reached the transfer position, so the image is not transferred, and the conveyor belt for conveying the copy paper rolls the toner image onto the photoreceptor. Such rolling has the disadvantageous effect that the individual toner images are compressed onto the photoreceptor and are damaged during transfer of the toner images to copy paper.

In order to avoid rolling of the toner image by the conveyor belt as described above, the electrostatic latent images on the individual photoreceptors are developed only when the copy paper is fed. In this case, the conveyor belt does not roll the toner image, but merely rolls the electrostatic latent image on the photoreceptor, and the problems described above due to rolling the toner image do not occur.

Since the photoreceptor following the first photoreceptor makes one or more complete revolutions to make a color copy, a cleaning device, a developer device, and a corona discharger, which are typically included with each photoreceptor, are also typically included in the imaging process. Acts only when necessary for the process.

The operating timing of the developing device and corona discharger is controlled electrically. That is, it is sufficient to stop the developing bias or reverse the polarity, or to stop outputting the high voltage, and the cleaning device may be designed so that it can be separated from the surface of the photoreceptor by a driving member such as a plunger.

Furthermore, if the color-separated images of the document are simultaneously exposed to each photoreceptor provided in the apparatus, a skip operation is performed from the second photoreceptor onward in order to synchronize the color-separated latent images of each photoreceptor. is necessary. However, this is done with great precision and with little mechanical cost.

Typically only three colors, yellow, magenta, and cyan toner, are required to produce a full color image. Therefore, only three photoreceptors need be provided. However, if black and white copies are to be made with this apparatus, a fourth photoreceptor may be provided for making black and white copies. in this case,
You can get black and white copies three times faster than color copies. Furthermore, in the configuration example of the present invention, the first photoreceptor on which a latent image is first formed may be provided with a black-and-white developing device that operates when only black-and-white copying is desired.

It will be seen from the drawings and description thereof that the structure of the color copying apparatus of the invention described above is substantially simple and that color copies can be made in rapid succession with this apparatus. You can know.

FIG. 1 shows a sectional view of the device of the first embodiment, and FIG. 2 shows a sectional view of the device of the second embodiment.

According to FIG. 1, an original is placed on a glass plate 1, and a scanning device consisting of an illumination lamp 2 and two movable plane mirrors 3.4 exposes the image of the original onto a photoreceptor in the form of a strip.

This mirror 3.4 is moved in the direction of arrow 5 to positions 3', 4' for exposure of the original. The mirror is at this position 3', 4
To re-expose the document from '', it is moved backwards to its starting position, usually at twice and a half speed. mirror 3
moves at three times the speed of the mirror 4 in order to maintain optical path length compensation for the exposure lens 6.

On the downstream side of the optical path of the exposure lens 6, there are color separation filters 7, 8, blue, green, and red. '9 and black and white ND filters 10 are provided, and one of the filters (blue filter turf in the figure) rotates and enters the path of the light beam.

A total reflection plane mirror 11 is provided behind the color filter 7 to direct the exposure light beam toward the first photoreceptor 13 via a plane mirror 12.

The first photoreceptor 13 and the second photoreceptor 13 . The third photoreceptor always rotates at a constant circumferential speed in the direction of arrow 14 while the device is in operation. The corona discharger 15 charges the photosensitive layer of the first photoreceptor 13, creating an electrostatic latent image of the exposed area A of the document at location B1. That is, the electrostatic charge m@ of the original 1 is formed on the photoreceptor 13 as a first color separated image according to the blue filter turf. The electrostatic latent image thus formed is later converted into a toner image on the photoreceptor 13 by a developer 16 containing yellow toner corresponding to the color separation image, depending on the development timing of other photoreceptors.

After the exposure of the first photoreceptor is completed, the mirror 11 is rotated by a cam or a solenoid so that the total reflection mirror 21 functions.

On the other hand, when the green filter 8 rotates and enters the optical path, at the position B2 on the second photoreceptor 23, at this time, the above-mentioned area A
is exposed to light, and an electrostatic latent image of the document image color-separated by the green filter 8 is generated on the second photoreceptor 23 . Similarly, this latent image is later developed by a developer 26 to produce a magenta toner image on the photoreceptor 23.

Next, the mirror 21 is rotated to position 21', and new exposure of the original l by the total reflection plane mirror 31 causes the areas A of the original to be produced at position B3 of the third photoreceptor 33, respectively, and the third photoreceptor An electrostatic latent image corresponding to a color-separated image by the red filter 9 is generated on the body 33. This image is later developed in a transfer context by a developer 36 using cyan toner. During this entire process, each photoreceptor 13
．． 23 and 33 are rotated in the directions of arrows 14, 24 and 34, and the individual color separated images are placed on the photoreceptor with the tip positions of the latent images angularly shifted from each other in the direction of rotation of the photoreceptor.

By the way, an endless conveyor belt 40 is provided below each photoreceptor.
is suspended by rollers 50 and 51 and is moving endlessly at the same speed as the circumferential speed of the photoreceptor. Copy paper, which is a transfer material, is placed in the cassette 41 and fed onto the belt 40 in synchronization by a pair of conveyance rollers 42 .

As a result, a suction device (not shown) suctions and holds the copy paper onto the belt 40. Then, by the transfer corona discharger 44, the toner image on the photoreceptor 13 is transferred to the passing copy paper.
It is temporally synchronized with the just developed toner image on the first photoreceptor 13.

The same thing applies to the second. This also occurs on the third photoreceptor 23.33.

In the example described in the specification, each photoreceptor has a diameter of 1
Therefore, the circumference of the photoreceptor is approximately 500 mm. On the circumference of the photoreceptor, an original of maximum A3 size according to the JIS standard is exposed while moving at the same speed as the scanning element. After all of the powder image has been transferred onto the copy paper, the copy paper is conveyed to a fusing device 47 and then deposited in a storage tray 48 as a finished copy.

In the device described above, each photoreceptor 13.23 and 33 further rotates while the scanning element moves back to the scanning start position, so that each photoreceptor 13.23 and 33 is positioned between the centers of rotation of such photoreceptors. Distance a (i.e. distance a between transfer positions
). Therefore, just as the copy paper reaches the position where the toner images of the individual extracted colors are transferred onto the copy paper, the toner images on the photoreceptor reach the transfer zone ClIC2,C, so that they are transferred onto the copy sheet. can form an image using three color toners that are precisely superimposed. That is, in the example, since the backward speed of the scanning element was set to be two and a half times faster than the scanning speed,
In the color-separated anatomical images of each photoreceptor, there is an image shift of 200 mm on the circumference from the photoreceptor on the upstream side to the upstream side in the rotation direction of the photoreceptor. Further, the distance between the transfer positions of each photoreceptor is set to an interval of 200 m, which is equal to the above-mentioned image shift. Therefore, as described above, the transfer zones C,, c2. C
3, it is possible to perfectly match the leading edge of each toner image on the copy sheet.

Development is started immediately before transfer so that the toner images corresponding to the color separation images of the document formed on these photoreceptors are not rolled by the belt 40 while the photoreceptors 13, 23, and 33 continue to rotate.

For this reason, the electrostatic latent image formed on the photoreceptor must be maintained for a long time, and for this purpose, a corona discharger 15.25
．． 35 and the cleaning device 17° 27.37 The structure is such that it does not act on the Fi photoreceptor as described above.

To make a black and white copy using the above device configuration,
Although black may be formed by subtractive color mixing using the three color toners, a developing device 18 having black developing toner may be provided separately from the developing device, and an ND filter 10 may be used in combination as necessary. . In this case, ND filter 10
is interposed in the path of the beam, the mirror 11 redirects the beam to the area B1. At present (the racking device 16 does not operate and only the developing device 18 with black toner operates), the corona dischargers 44, 45, and 46 for transfer apply a transfer electric field to the transfer sheet via the belt 40. act.

The following FIG. 2 is an embodiment of another color device of the present invention.

- Parts corresponding to FIG. 1 above have the same designation numbers. In the apparatus according to FIG. 2, transmitting mirrors 52, 53 are provided downstream of the optical path of the exposure lens 6. The other mirror 31 is a fixed total reflection mirror. In the apparatus shown in FIG. 2, zones B1, B2. At B3, latent images of color separation images corresponding to the document pressure are simultaneously formed on the photoreceptor.

In this structure, each color image is shifted in the circumferential direction of each photoreceptor as described above, so that it is necessary to occupy an appropriate angular position so that synchronization can be achieved during transfer. For this reason, the second. After forming the latent image, the third photoreceptor 23.33 is rotated in the opposite direction by an appropriate angle, and the leading edge of the image is sequentially shifted by 200+w. During this reverse rotation, the belt 40 with the transfer corona dischargers 44, 45, 46 pivots to the position shown by the broken line, so that the toner image is not rubbed and blurred by the contacting belt. That is, the roller 51 is at position #5
1', and 44°45.46 is at position 44', 4
Move to 5', 46'.

The mode of operation during transfer is the same as in the device according to FIG.

In the apparatus according to FIG. 2, the developer 16 uses black toner in addition to subtractive color mixing when making black and white copies.
is disposed on the first photoconductor, and the ND filter 10 is rotated and replaced in the position of the filter 7, and a latent image corresponding to the original image is developed with black toner.

In this way, when creating a black and white copy, by providing a developing device using black toner on the first photosensitive drum, it is possible to create a black and white copy in the shortest possible time. Furthermore, in the apparatus shown in FIG. 2, in order to match the timing of transfer,
In addition to rotating the photosensitive drum by a predetermined amount with the belt 40 separated from each photosensitive member, the rotation of the photosensitive drum may be temporarily stopped by disengaging the clutch for a predetermined time using a timer. Further, the photoreceptor and the latent image forming process are not limited to the illustrated example.

Further, as means for conveying the copy paper, in addition to the suction method, it is also possible to use electrostatic adsorption, grippers, or the like.

[Brief explanation of the drawing]

FIGS. 1 and 2 are sectional views of a color copying apparatus to which the present invention is applied. In the figure, 13.23.33 is a photoreceptor, 7°8.9 is a color separation filter, 16.26.36 is a color developer, 41 is copy paper, and 44°45.46 is a transfer corona discharger. , 40 is a copy ha! Send/＜
root.

Claims (2)

[Claims] (1) A color copying apparatus that forms a color image on a transfer material includes: an optical means for scanning a document and exposing the document image to a photoreceptor; a filter means for color-separating the document image; Second. a third photoreceptor, a means for developing a latent image corresponding to the color separation image formed on each of the photoreceptors, a means for supplying a transfer material to each of the photoreceptors, and a transfer material for the toner image on the photoreceptor. The leading edge of the latent image to be formed on the photoreceptor on the downstream side in the conveying direction of the transfer material is set to A color copying device characterized by delaying the formation by the distance of the transfer position. (2) A color copying apparatus that forms a color image on a transfer material, which includes an optical means for scanning an original and exposing the original image to a photoreceptor, a filter means for color-separating the original image; Second. a third photoreceptor; a means for developing a latent image corresponding to the color separation image formed on each of the photoreceptors; a means for supplying a transfer material to each of the photoreceptors; and a means for transferring to the above-mentioned No. Second. A color separated image is simultaneously formed on the third photoconductor, and when transferring, the rotation of the downstream photoconductor in the conveying direction of the transfer material is regulated, and the tip of the latent image on the downstream photoconductor is moved to the upstream side. A color copying device characterized in that the transfer position of a fleshy photoconductor is delayed by a distance from the tip position of a latent image on the photoconductor.