JPH0391745A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent generation of uneveness in density when a multiple number of images are formed on a piece of paper in both side copying and synthetic copying, etc., by setting pressure imparted by a pressure developing device to be smaller for the later image processing when image formation is carried out a multiple number of times on the same piece of paper by repeatedly carrying out the image forming process a multiple number of times. CONSTITUTION:When exposure process is finished, pressure developing process is carried out, but first, the number of times the copying process is carried out on the same piece of paper including this image processing is discriminated. If it is the first time, the paper is fed from a paper cassette, and an eccentric centering cam 58 of the pressure developing device is rotated N1 times and made to impart pressure to pressure rolls 51 and 52. In a second (back side) copying, the rotating amount of the eccentric centering cam 58 is made N2, and the pressure imparted to the pressuring rolls is made smaller than in the front side copying. Thus, by setting the pressuring force in the first copying and the pressuring force in the second copying in the both side copying and synthetic copying to be varied, the image density is not made excessively dark in the second copying.

Description

DETAILED DESCRIPTION OF THE INVENTION (i1) Industrial Application Field This invention relates to photocurable materials. The present invention relates to an improvement in an image forming apparatus that forms an image using a photosensitive pressure sensitive sheet coated with photosensitive pressure sensitive microcapsules encapsulating a dye or the like.

(bl) Conventional technology When forming images using an image forming device such as a copying machine, images may be formed on both sides of a sheet of paper, or multiple images may be superimposed on one side. This is called a precept copy.

Double-sided copy of the above using a photosensitive pressure sensitive sheet. When copying or copying, a photosensitive pressure-sensitive sheet for plain paper is usually used. For example, JP-A-61-251837, JP-A-6
1-251838, etc., and microcapsules containing a color developer that develops the color-forming dye, which are coated on the same sheet surface; Unlike the photosensitive pressure-sensitive sheet coated with microcapsules containing colored dyes as shown in No. 1984-3984'4, there is no need to coat the paper with a color developer.

When the photosensitive pressure-sensitive sheet is exposed to image-forming light such as light reflected from an original, partial microcapsules are hardened and a latent image is formed (exposure step). Then, by superimposing a sheet of paper on this latent image and applying pressure, the uncured microcapsules are destroyed, and the dye and the like flow out onto the sheet of paper, making the image visible (pressure development process).

(C) Problem to be Solved by the Invention However, when double-sided copying or combined copying is performed using the photosensitive pressure-sensitive sheet, the density of the image that is printed later may be higher.

Such density unevenness is particularly noticeable when a plurality of images are combined on one page or when copying, resulting in a very poor appearance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that prevents uneven image density from occurring when a plurality of images are formed on a single sheet of paper, such as during double-sided copying or double-sided copying. The purpose is

(Means for Solving Problem d1) The present invention overlays a photosensitive pressure-sensitive sheet coated with photosensitive pressure-sensitive microcapsules with paper and passes it through a pressure developing device to destroy the microcapsules and encapsulate them. In an image forming apparatus that forms an image on a sheet of paper using an object, when the image forming process is repeated several times to form an image on the same sheet of paper, the pressure applied by the pressure developing device is The present invention is characterized by having a pressure setting means that is set to a smaller value as the image-form command processing is performed.

(In an image forming device that forms an image using an EL-acting photosensitive pressure-sensitive sheet, it is necessary to apply a large pressure to destroy microcapsules (particle size of about 5 μm), for example, 20 CII +
A pressure roller to which a high pressure of nearly 2 tons is applied is used as a pressure developing device. When such a pressure developing device is used, even a slight change in the thickness of the photosensitive pressure sensitive sheet, paper, etc. changes the pressure applied to them.

That is, as the paper becomes thicker, the pressing force increases. The increased force U of the pressurizing force is directly related to the degree of destruction of the microcapsules,
The microcapsules are easily destroyed and the image density becomes high. Furthermore, when a plurality of images are formed on one surface, once pressure development is performed, the smoothness of the paper increases due to dyes and the like, making it easier to apply pressure and increasing the image density.

In the present invention, when images are formed on one sheet of paper several times in a superimposed manner, the pressure of the pressure developing device is set to be lower the later the image forming process is performed. Therefore, the photosensitive pressure sensitive sheet is pressed by a pressure developing device. Even if the number of times of pressure development increases, excessive high pressure will not be applied to the paper.

(f) Embodiment FIG. 3 is a schematic front view of a copying machine capable of double-sided copying and double-sided copying.

On the top of the copying machine body is a document table 1 made of transparent glass.
is provided, and the original to be copied is placed on it. An optical system including a light source, a mirror, a lens, etc. is arranged below the document table l, and guides reflected light from the document to an exposure section, which will be described later. A media cartridge 3 is provided on the left side of the central portion of the copying machine main body so that it can be freely attached to and removed from the copying machine main body. The media cartridge cartridge 3 includes a supply shaft 31 and a take-up shaft 32.
An unused photosensitive pressure sensitive sheet 4 is wound around the sheet.

The photosensitive and pressure sensitive sheet 4 is pulled out from the media cartridge and placed in an exposure section P1, a buffer roller IO, and a pressure developing section P2.
The film is wound onto the winding shaft 32 via the winding shaft 32.

As described above, reflected light from the original is guided to the exposure portion P1, forming a latent image on the photosensitive pressure sensitive sheet. In the pressure developing section P2, a paper is superimposed on the latent image and pressure is applied to form an image on the paper.The bumper roller IO is used to separately perform the above-mentioned exposure processing and pressure development processing. Since the photosensitive pressure sensitive sheet 4 has different sensitivity to light and sensitivity to pressure (light sensitivity is generally lower), if exposure processing and pressure development processing are performed simultaneously, one of the processing conditions will deteriorate. Therefore, during exposure, move the batho roller 10 to arrow F.
direction, the media sheet 4 is pulled out, and the exposed media sheet is placed in the upper right part of the exposure section to perform only exposure processing. When the exposure process is completed, the bath roller 10 is moved in the direction of arrow R, and the exposed media sheet is sent to the pressure nozzle developing section P2 for pressure development.

FIG. 4 is a front cross-sectional view of the pressure developing device that monitors the pressure developing section P2.

The pressure developing device includes an upper pressure roller 51, a lower pressure roller 52, and a pressure up roller 53, 53 that urges the upper pressure roller 51 downward.

The upper pressure roller 5l and the bank associative roller 53 are supported by the upper holder 54, and the lower pressure roller 52 is supported by the lower holder 55.
is supported by The upper and lower polders 5455 rotate about the fulcrum shaft 56 to bring the upper and lower pressure rollers 51 and 52 into the pressurized/pressure-released state. In other words, the upper and lower holders are connected to the spring 5.
7, the upper holder 54 is lifted up against the urging force by the rotation of the eccentric cam 58, and the pressure is relieved or released. The driving force of a motor 59 is transmitted to the eccentric cam 58 via a plurality of gears. Depending on the amount of rotation of the motor 59, the pressure of the pressure rollers 51, 52 is set from maximum pressure to intermediate pressure to pressure release. The gear is equipped with a one-way clutch, and when the pressure is released or the pressure is at an intermediate level, the eccentric cam 58
This prevents the risk of rotating in the opposite direction.

Paper cassettes 61 and 62 are provided on the right side of the main body of the copying machine, and a paper cassette 6 is housed therein. Further, on the left side of the copying machine main body, a paper ejection tray 7 and an ejection roller 71 are provided just in front of the paper ejection tray 7. Between the paper cassette 61 (or 62) and the ejection tray 7, a paper transport section including a registration roller 63, a pressure developing section P2, and a fixing device 8 is arranged. Normally, the paper 6 is fed from a paper cassette 61 (or 62), stopped once by a registration roller 63, and then
At a predetermined timing, the latent image is sent to the pressure developing section P2 and is pressed while being superimposed on the latent image on the photosensitive pressure sensitive sheet 4.
The image of st. Then, after being fixed by the fixing device 8, the image is discharged onto the waving tray 7. However, it operates differently in double-sided copy mode or double-sided copy mode. An intermediate tray section 9 is provided below the paper conveyance section, and the paper on which an image has been formed is sent to this intermediate tray section 9 and then returned to the paper conveyance section after the registration roller 63 to form an image. Processing takes place.

A branching point to the ejection tray side and the intermediate tray side is provided behind the fixing device 8. The turning point is Furasob 91.92
have. The flapper 91 transfers the fixed paper to the ejection tray 7 side (in the direction of arrow A) or to the intermediate tray section 9 side (arrow B).
direction).

Normally, the fused paper is sent to the ejection 1/ray 7 side in the off state (double-dashed line state), but during composite copying, it is turned on and the fused paper is in the state shown by the solid line in the figure, and the fixed paper is sent to the intermediate tray section 9. Send it in. In addition, Furasop 92 is in the off position (double-dashed line in the figure)
The paper sent in is sent to the wandering roller 71, and the paper sandwiched between the wandering rollers 7l in the on state (solid line) is sent to the intermediate I/lay section 9. That is, when performing double-sided copying, it is necessary to reverse the front and back of the paper, and this is done by the paper discharge roller 71 and the flapper 92. When the front and back sides are reversed, the ejecting roller 71 feeds the paper in the eight directions of the arrow until just before the rear end (at this time, the flapper 92 is turned off). Then, the flap 92 is turned on at the same time as the paper discharge roller 71 is reversed, so that the paper is sent to the intermediate tray section 9 in the direction of arrow C. At this time, the trailing edge of the paper is the sensor S1.
When the sensor II-31 detects the trailing edge of the paper, the paper discharge roller 71 temporarily stops and then starts rotating in reverse. Also, S2 in the intermediate tray section 9. S3 is a sensor for detecting paper jam.

FIG. 1 is a flowchart showing the main processing procedure in double-sided coby mode. Duplex Coby Mode is selected from the operation panel on the main body of the copying machine. When the double-sided copy mode is started, first, set O to K at n1 and proceed to n2.

Note that K is a value indicating the number of image formations on one sheet of paper.

At step n2, the photosensitive pressure sensitive sheet is pulled out from the supply shaft and subjected to exposure processing. When the exposure process is completed, a pressure development process is performed, but first it is determined how many times the image forming process is a copy process on one sheet of paper (n3). If it is the first time, the paper is fed from the paper case 61 (or 62), and the eccentric cam 58 of the pressure developing device is rotated N1 times to apply pressure to the pressure rollers 51 and 52 (n4-n5). As described above, the pressure of the pressure roller is adjusted by the amount of rotation of the eccentric cam 58. The amount of rotation during the first (front) copying is N, and at this time high pressure is applied.

When copying for the second time (back side), the paper fed from the intermediate tray section 9 is fed to the pressure developing section P2, and then pressure is applied to the pressure roller. The amount of rotation of the eccentric cam 58 at this time is N2, and the pressure applied to the pressure roller is lower than that during front copying (n6, n7).

Pressure development processing is performed by passing the photosensitive and pressure sensitive sheets 4, Wi, and 6 under this pressure, and when this is completed, the eccentric cam 58 rotates again to release the pressure on the pressure roller (n8 -n9). n10, nil adds 1 to K,
This is the step of determining the value (how many times it has been copied). If the process is the first time, n.
1 At step 2, the paper is turned upside down and then sent to the intermediate tray section 9. The paper is on registration roller 63
After passing through an image forming process of n2-n3→n6→n7→n8, etc., it is discharged to the ejection tray 7 at n13.

Further, FIG. 2 is a flowchart 1 showing the main processing procedure during composite copying, and the difference from the processing procedure for double-sided copying in FIG. 1 is the rotation amount N3 of the eccentric cam at n20,
0. 2. Do not turn the front and back sides in step 1. The reason why the rotation amount is set to N is that during composite copying, the smoothness of the paper increases, making it easier to apply pressure to the microcapsules, so the pressure is made smaller.

As described above, the pressure force for the first copy and the pressure force for the second copy during double-sided copying and joint copying are set differently, and as a result, the image density of the second copy is particularly high. It becomes too much or it disappears.

In the embodiment, the pressure setting means is indicated by n in the flowchart.
Corresponds to l n3 nlO and n5, n7, n20. Also, in this embodiment, the case where the copy process is performed twice on the paper has been explained, but if more images are to be formed on one sheet of paper, the pressure may be lowered during the later image forming process. Just go.

(g) Effects of the invention According to the invention, as described above, when image forming processing is repeated several times on a sheet of paper, the pressure applied to the pressure developing device is reduced as the image forming processing is repeated. By doing so, it is possible to prevent uneven image density from occurring and to eliminate deterioration in image quality.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the processing procedure for double-sided copying, Fig. 2 is a flowchart showing the processing procedure for double-sided copying, and Fig. 3 is a flowchart showing the processing procedure for double-sided copying. FIG. 4 is a schematic front view of a copying machine capable of combining and copying, and FIG. 4 is a front sectional view of a pressure developing device. Media sheet, pressure developing device, one-purpose tray, wandering paper tray, one intermediate tray section, lO-bath roller, 51, 52 one-pressure roller, 57-spring, 58- eccentric cam, 61.62 = paper cassette,, 71-discharge roller, 91.92-flap, P1-exposure section, P2-pressure development section.

Claims (1)

[Claims] (1) A photosensitive pressure-sensitive sheet coated with photosensitive pressure-sensitive microcapsules and paper are overlapped and passed through a pressure developing device to destroy the microcapsules and form an image on the paper using their contents. In the image forming apparatus, when the image forming process is repeated multiple times to form an image multiple times on the same sheet, the pressure applied by the pressure developing device is
An image forming apparatus characterized by comprising a pressure setting means that sets a pressure smaller as the image forming process is performed later.