JPH0526585Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention relates to a color copying machine.
It relates to color separation in such devices and is applicable to color scanner technology.

(Prior Art) Conventionally, a color copying machine is a device that forms a color-separated optical image on a single photoreceptor using a color separation filter, transfers it, and repeats this process three times to obtain a color copy. However, one photoreceptor must be charged, exposed, and exposed at least three times.
It is necessary to perform image transfer and transfer, and the copying speed is slow.

(Problem to be solved by the invention) The invention uses a so-called three-part slit simultaneous exposure method that uses multiple photoreceptors and simultaneously forms color-separated light images at the exposure positions of each photoreceptor. The purpose is to reduce the occurrence of bending of light rays transmitted through dichroic mirrors used for color separation, and to reduce the positional deviation of each image on transfer paper.

(Means for Solving the Problems) In order to achieve the above object, the present invention separates reflected light from an original into light beams corresponding to the number of photoreceptors on the image side of an imaging lens, and An electrostatic latent image is formed on each photoconductor as a color-separated light image, and each electrostatic latent image is developed with colored toner corresponding to the color separation, and then transferred from each photoconductor onto the same transfer paper. This color copying machine is characterized in that the total thickness of a plurality of dichroic mirrors arranged to direct reflected light from an original to each photoreceptor is within 6 mm.

(Function) With the configuration of the present invention, in a full-color copying machine that simultaneously exposes multiple photoreceptors with three-part slits, the total thickness of the dichroic mirrors is within 6 mm. It is possible to reduce the curvature of the image based on the image.

(Embodiment) An outline of an embodiment of a full-color copying machine to which the present invention is applied will be explained with reference to FIG.

The document on the document table 1 is illuminated by an illumination unit consisting of an illumination lamp 3 and a reflector 4, and the reflected light is transmitted to the first mirror 11, second mirror 12, third mirror 13, fourth mirror 14, and lens. 2. It is guided to the sixth mirror 16 via the fifth mirror 15.

The sixth mirror 16 is a reflective mirror coated with a multilayer film, and is designed to reflect component light of one color among blue light, green light, and red light, and to transmit component light of the other two colors. ing.

In the embodiment, the light reflected by the sixth mirror 16 is blue light, and this blue light is transmitted to the first photoreceptor belt 5.
The image is formed at the projection position 21 of No. 3.

The light beam transmitted through the sixth mirror 16 is reflected by the band seventh mirror 17, and the reflected light, green light, forms an image at the projection position 22 of the second photoreceptor belt 53'. Like the sixth mirror 16, the seventh mirror 17 is a reflective mirror coated with a multilayer film, and
Due to the performance of the multilayer coating layer, only green light is reflected and red light is transmitted.

Then, the red light that has passed through the seventh mirror 17 is transferred to the third photoreceptor belt 5 by the eighth mirror 18.
3'', and an image is formed at the red light projection position 23.

In the color separation process described above, the first photoreceptor belt 53 receives blue light, the second photoreceptor belt 5
3' is exposed to green light, and the third photoreceptor belt 53'' is exposed to red light, but the order of color separation depends on the wavelength energy distribution of the light source, the transmitted light characteristics of the lens, and the sensitivity characteristics of the photoreceptor. The optimum method and order are adopted depending on the toner transmittance and other factors.

During image formation, the first to third photoreceptor belts 53 to 5
3'' is driven in the direction of the arrow by clockwise rotation of the respective drive rollers 51 to 51''.

Each photoreceptor belt 53 to 53'' is initialized by each quencher 41 to 41'', and then fully charged by each main charger 43 to 43'',
Erasers 42 to 42'' of the light emitting diode array selectively erase charges outside the imaging area.

At each light projection position 21, 22, 23 of each photoreceptor belt 53-53'', original image exposure color-separated into blue light, green light, and red light is applied simultaneously.

Exposure scanning of the original is similar to a normal copying optical system, but there are two original scanning mirrors, a first mirror 11 and a second mirror 12, which are paired downstream of the lens. This is because it is impossible to increase the number of reflective surfaces. During exposure scanning of the original, the blocks of the first mirror 11, second mirror 12 and illumination systems 3 and 4 are moved to positions 11' and 12', and the third mirror 1 is moved to positions 11' and 12'.
3. The block of the fourth mirror 14 moves to 13' and 14' at 1/2 the speed and moving distance of the previous block and completes.

As a result, color-separated electrostatic images are formed on the surface of each photoreceptor belt.

In the developing process, the first photoreceptor belt 53 is exposed to blue light, so it is visualized in the developing device 61 with yellow toner, which is a complementary color to the first photoreceptor belt 53, and similarly, the second photoreceptor belt 53' is exposed to blue light. Since the third photoreceptor belt 53'' has received red exposure, the developing device 61' uses magenta toner, which is a complementary color, and the developing device 61'' uses magenta toner, which is a complementary color. They are each visualized using cyan toner, which has the same relationship as .

The surface of the photoreceptor on which these toner images have been formed undergoes charge removal by pre-transfer charge eliminators 64, 64', 64'', respectively, and advances to each transfer position 21', 22', 23'. Each toner image is transferred to each transfer position. The timing of reaching
Settings are made so that each toner image is transferred to the same position on the transfer paper.

The transfer paper 70 is fed to a pair of registration rollers 72 and 73 by a paper feed roller 71, and is moved so as to match the leading edge position of the toner image on the third photoreceptor belt 53''.
It is supplied onto the transfer belt 54 while being lightly pressed by a press roller 74 at the right timing. The transfer belt 54 is driven in the direction of the arrow by counterclockwise rotation of the drive roller 55. At this time,
The transfer belt 54 is attached to each transfer position 21', 2
2' and 23' are in reliable contact with each photoreceptor belt, and transfer is performed reliably.

The transfer paper fed onto the transfer belt 54 reaches the transfer position 23' of the third photoreceptor belt 53'', where the cyan toner image is transferred by the transfer charger 63'', and then it is sequentially moved to the transfer position 23' of the second photoreceptor belt 53'. 2
A magenta toner image is transferred to the transfer position 2' of the first photoreceptor belt 53, and a yellow toner image is transferred to the transfer position 21' of the first photoreceptor belt 53 by transfer chargers 63' and 63, respectively.
Weight is transferred.

As a result, overlapping images of cyan, magenta, and yellow are obtained on the transfer paper that has passed through the transfer position 21'.

In order to prevent color misregistration of these three-color toner images, the circumferential length of each of the first to third photoreceptor belts from the exposure position to the transfer position and the distance between each transfer position are set as follows: 23, 23 '+23', 22' = 22, 22' 23, 23' + 23', 21' = 22, 22' + 22', 21' = 21, 21'.

In addition, as shown in FIG. 1, the distance α between the sixth and seventh mirrors, the distance β between the seventh and eighth mirrors, the distance α′ between the first transfer position and the second transfer position, If the distance between the transcription position and the third transcription position is β', then α
When configured so that =α' and β=β', the toner images of each color match, and a combined image without color shift can be obtained.

The transfer paper that has passed through the transfer position 21' is separated from the transfer belt 54 at the drive roller 55, and then
The image is fixed by the fixing device 75 and ejected onto the paper ejection tray 76, resulting in a full-color copy.

On the other hand, each of the photoreceptor belts 53 to 53'' is cleaned by each cleaning device 62 to 62'' after the transfer.
is cleaned and prepared for the start of the next copy.

Further, the transfer belt 54 is cleaned by a cleaning device 66 after being neutralized by a static eliminating device 65 using AC double corona.

In addition, 5 is the optical system housing, 6 is the upper part of the main body,
7 is a lower part of the main body, 8 is a caster, 33 is a color balance adjustment filter, 52 to 52'' are each photosensitive belt driven roller, and 56 is a transfer belt and driven roller.

In the present invention, the sixth mirror 1 shown in FIG.
6. Each reflecting mirror of the seventh mirror 17 is coated with a multilayer film, and the material of these reflecting mirrors is glass. Generally, glass has a higher density than air, and the transmitted light is refracted. This reflecting mirror is generally called a dichroic mirror, and the light beam traveling from the center of the lens 2 enters the sixth mirror 16 near the optical axis and both ends of the slit, respectively.
The reflected light is imaged on the exposure section 21, and the transmitted light is reflected on the seventh mirror 17, and the reflected light is focused on the exposure section 22.
image is formed. Comparing the image formed by the exposure section 21 and the image formed by the exposure section 22, it is found that the curvature of the image is caused by the substantial difference in the thickness of the mirror near the optical axis (center) and near both ends. The degree changes.

In other words, in the case of FIG. 1, there is an image formed by the light reflected by the sixth mirror 16, an image formed by the light transmitted through the sixth mirror 16 and reflected by the seventh mirror 17, and an image formed by the light transmitted through the seventh mirror 17. However, if the images formed by the reflected light from the eighth mirror 18 are transferred at the transfer sections 23', 22', and 21' so that the centers of the images overlap in a state where there are no other errors, the centers of the images will be The more they overlap and the closer you go to the end, the larger the deviation becomes. In this case, if the image is one black line, the transferred image at 21' of the image formed by the sixth mirror 16 will be a straight line, as shown in FIG. The transferred image at 22' of the transmitted image overlaps in the center, but there is a shift at both ends, and the transferred image at 23' of the image transmitted twice through the dichroic mirror overlaps at the center, but there is a shift at both ends.
The transferred images overlap at the center, but the deviation at both ends becomes even larger. The arrow indicates the direction of movement of the transfer paper.

Therefore, the relationship between the thickness of the dichroic mirror and the image shift is shown in FIGS. 2 to 4. Here, the f value of the lens commonly used in copying machines,
± from the center to the edge when changing the thickness of the dichroic mirror inserted into the optical path from 190mm to 230mm
The image curvature at 150mm was determined by experiment. The thickness of the dichroic mirror is 2 mm in FIG. 2, 4 mm in FIG. 3, and 6 mm in FIG. 4. Experiments have shown that the thickness of the dichroic mirror has the largest contribution to image curvature, and even if the f-number of the lens is changed from 190 mm to 400 mm, there is little change in image curvature. It was also confirmed that the bending is determined by the total thickness, regardless of the number of dichroic mirrors inserted in the optical path.

If the error in superimposing the three-color images as a copy image is 0.1 mm or more, it is not acceptable as image deterioration occurs. As is clear from Figure 4,
If the thickness of the dichroic mirror is 6mm,
A bend of less than 0.1 mm occurs at a position of ±150 mm from the center, and if there is no error in transporting the transfer paper or timing error in superimposing each image, some image deterioration can be tolerated.

In the present invention, when using a transmission type mirror, that is, multiple dichroic mirrors in a three-part optical path optical system, it is possible to obtain an image with less image curvature by keeping the total thickness of the dichroic mirrors within 6 mm. I can do it. FIG. 1 shows an embodiment in which two dichroic mirrors are used.

(Effects of the invention) With the configuration of the invention, it is possible to reduce image curvature caused by dichroic mirrors in full-color copying machines that perform three-part slit simultaneous exposure on multiple photoreceptors, which helps improve color image quality. It is effective.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram of an embodiment of a full-color copying machine to which the present invention is applied; FIG.
4 is a graph showing the relationship between the thickness of the dichroic mirror and the deviation of the image, and FIG. 5 is a schematic diagram showing the deviation of the image that occurs on the transfer paper. 16...6th mirror, 17...7th mirror.

Claims (1)

[Claim for Utility Model Registration] The reflected light from the original is separated into light beams corresponding to the number of photoreceptors on the image side of the imaging lens, and the separated light beams are used as color-separated light images for each photoreceptor. In a color copying machine that forms an electrostatic latent image on a document, develops each electrostatic latent image with colored toner corresponding to color separation, and transfers it from each photoreceptor to the same transfer paper, the light reflected from the document is A color separation device for a color copying machine, characterized in that the total thickness of a plurality of dichroic mirrors arranged to face each photoreceptor is within 6 mm.