JPH0321951A - Image forming device equipped with a pressure developing device - Google Patents

Abstract

PURPOSE:To prevent the generation of deflection in press rollers and the wrin kling of paper by pressuring the press rollers by the pressure corresponding to the size of the paper. CONSTITUTION:An eccentric cam 17 rotates and the pressure regulation is executed at the time of pressure development. The pressure is maximized in the state in which the max. diameter position(a) is lowest. The pressure decreases successively when the cam is further rotated from this gosition. A one-way clutch 18e is provided and, therefore, even if the eccentric cam 17 is stopped in an unstable position, the backward rotation of the eccentric cam 17 is stopped in an unstable position, the backward rotation of the eccentric cam 17 does not aries. The relation between the rotating quantity of the eccen tric cam and the size of the paper is such that the rotating quantity of the eccentric cam is more largely set and the pressure of the press rollers 11, 12 is smaller as the size of the paper is smaller. The pressure acting on the press rollers is changed if the rotating quantity of the eccentric cam is changed accord ing to the size of the paper in this way. The deflection is thus prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an image forming apparatus that performs development processing by applying pressure using a pressure roller, and relates to a device that adjusts the pressure of the pressure roller.

(b) Prior Art A method for releasing the pressure using an eccentric cam in a pressure developing device having a pressure roller that is pressurized with high pressure is disclosed in Japanese Patent Laid-Open No. 1983-3-92-954. There is.

That is, pressurization/pressure release is performed by rotating the eccentric cam.

By releasing the pressure, it becomes easier to clear jams in the pressure roller section and perform maintenance operations, and by releasing the pressure when paper gets caught, it is possible to prevent sudden torque fluctuations. (C) Invention solves the problem. As mentioned above, the pressure roller is pressurized with high pressure. Specifically, a pressure of nearly 2 tons is applied to both ends of a 20CII1 pressure roller. However, when paper is passed through such a pressure roller, there is a problem in that the pressure in the axial direction of the pressure roller changes depending on the paper size (paper width in the direction perpendicular to the paper conveyance direction).

That is, when the paper size becomes smaller, the paper passes through the center of the pressure roller, which causes the pressure roller to bend, causing uneven pressure distribution in the axial direction. The uneven pressure distribution causes uneven development and wrinkles in the paper.

Furthermore, since the pressing force per unit line segment differs depending on the paper size, the color density of the image changes when the paper size changes, making it difficult to maintain the quality of the formed image constant.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus equipped with a pressure developing device that can solve the above problem by adjusting the pressure applied to the pressure roller according to the paper size.

(d) Means for Solving the Problems This invention includes a pressurizing device that pressurizes a pair of pressure rollers;
In an image forming apparatus equipped with a pressure developing device including an eccentric cam that adjusts or releases pressure against the force of the pressure device, and a drive force transmission device that transmits driving force to the eccentric cam, the drive The force transmitting device includes a one-way clutch, a means for manually controlling the size of the paper that passes through the pressure roller, and a means for setting the amount of rotation of the eccentric cam according to the paper size. .

(e) Effect In the present invention, the eccentric cam can only be rotated in one direction because the driving force transmission device is equipped with a one-way cradling. Therefore, if you stop the eccentric cam on a surface that requires a large torque to rotate the eccentric cam, it will not go backwards even if the state of the eccentric cam is unstable, and it will be possible to stop the eccentric cam at an appropriate position. can. By changing the stop position of the eccentric cam, the force applied to the pressure roller can be adjusted.

On the other hand, the pressure roller is deflected because the force applied to the pressure roller is too large, and the deflection can be eliminated by adjusting the pressure according to the paper size. That is, by changing the amount of rotation of the eccentric cam according to the paper size, the pressure applied to the pressure roller changes and warping can be prevented.

Furthermore, since the pressure applied to both ends of the pressure roller is adjusted according to the paper size, the pressure per unit line segment becomes uniform, and an image with a constant density can always be obtained even if the paper size differs.

(f) Embodiment FIG. 6 is a diagram showing the structure of an image forming apparatus equipped with a pressure developing device.

A document table 51 made of transparent hard glass is provided on the top surface of the image forming apparatus main body. A document 52 to be copied is placed on the document table 51 with the document surface facing downward. An optical system 53 including a light source, a mirror, a lens, etc. is provided below the document table 51. A document 52 on a document table 51 is scanned by an optical system 53, and reflected light from the document is guided to an exposure point, which will be described later.

A media seat mounting section is provided on the left side of the image forming apparatus main body. The media sheet 54 is a sheet made of a light-reflective material such as aluminum, and a photo-curable material.
It is coated with microcapsules with a particle size of approximately 10 to 20 μm that encapsulate a coloring dye or the like. The microcapsules are cured by exposure to light and destroyed by pressure, allowing the color-forming dye to flow out. This media sheet is paired with a receiver sheet to be described later to form a photosensitive pressure sensitive sheet. The receiver sheet is a sheet of paper coated with a thermoplastic resin and a developing material (that causes the color-forming dye to develop color).

The media sheet 54 is wound around a supply shaft 55 and housed in a media cartridge 56 made of a light-shielding material to be protected from external light and external pressure. The media sheet 54 is pulled out from the media cartridge cartridge 56 and exposed at the exposure point P.
1. The film is wound up on the winding shaft 57 via the buffer roller 58 and the pressure development bore l-P2. During exposure, the buffer roller 58 moves in the eight directions of the arrow to move the media sheet 5.
4 and move the exposed media sheet to the upper right part of the exposure point P1. This media sheet is pulled by the pressure device 1 during pressure development and is sent to the pressure development point P2. That is, the pressure development process is performed after the exposure process is completed.

FIG. 3 is a sectional view of the pressure developing device, and FIG. 4 is an external view of the device.

The pressure developing device 1 has upper and lower pressure rollers 11 and 12. Pressure development point P is between the upper and lower pressure rollers 11 and 12
It is 2. The upper pressure roller 11 is held by an upper holder 13 so as to be movable in the vertical direction. and upper pressure roller l1
Above the bank associative roller 11a. 1 lb is rotatably held. In addition, the lower pressure roller 12 is attached to the lower holder 1.
4 and is rotatably held. Upper and lower holder 13.14
is rotatably provided around a fulcrum shaft 15, and is pressurized/released by a spring I6 and an eccentric cam 17. When the upper and lower holders 13.14 are pressurized, the upper and lower pressure rollers 11.12 are also pressurized, and when the upper and lower holders 13.14 are released from pressure, the upper and lower pressure rollers 11.12 are also released. In addition, the upper and lower pressure rollers 1
1.12 is pressurized only during pressure development, and is in a pressure-released state at other times.

The driving force of the main motor 19 is transmitted to the eccentric cam 17 by a driving force transmitting device 18 . The driving force transmission device 18 transmits the driving force of the main motor 19 to the eccentric cam l7 through gears 18a to 18d.

Further, the gear 18b is provided with a one-way clutch 18e, which prevents the gears 18a to 18d and the eccentric cam 17 from rotating in the opposite direction. A slit circle Fi20 is provided coaxially with the eccentric cam 17. A plurality of slits 21 are provided in the SJ-soto disk 20. This slit 21 is detected by a sensor S1 for detecting the rotation amount of the eccentric cam. Further, a slit 22 is further provided inside the slit 2. This slit 22 corresponds to the maximum diameter position a of the eccentric cam, and the rotation reference position of the eccentric cam is detected by the sensor S1.

FIG. 2(A) is a diagram showing the rotational state of the eccentric cam 17.

In the pressure released state, the eccentric cam is in the state shown by the solid line, and the maximum diameter position a is directly above.

During pressure development, the eccentric cam rotates to adjust the pressure. In other words, the pressure is maximum when the maximum diameter position a is directly below, and as it rotates further from this position, it reaches 17'
The pressure decreases as shown at 17".
Even if the eccentric cam is stopped at an unstable position such as '17'', the one-way clutch TSE is provided so that the eccentric cam will not rotate in the opposite direction. The larger the number, the more the external force is alleviated and the cam can be stopped stably.Second
Figure (B) is a diagram showing the relationship between the rotation amount of the eccentric cam and the paper size (paper width). The smaller the paper size, the larger the rotation amount of the eccentric cam is set, and the lower the pressure of the pressure roller. This is because if large pressure is applied when the paper size is small, the pressure roller will bend, causing wrinkles in the paper and uneven development.

In FIG. 6, a manual feed tray 2 and a paper drawer 3.4 are provided on the right side of the main body of the image forming apparatus. A receiver sheet (paper) 5 is stored in the manual feed tray 2 and the paper cassette 34. A paper size sensor S2 is provided below the manual feed tray 2, and paper size sensors S3 and S4 are provided at the mounting portion of the paper cassette 3.4.

These sensors S2 to S4 detect the sizes of the receipt sheets stored in the manual feed tray 2 and the paper cassettes 3 and 4. During pressure development, either the manual feed tray 2 or the paper cassette 3 or 4 is selected by input from the operation panel on the main body of the image forming apparatus, and the receiver sheet 5 is fed to the pressure developing apparatus 1.

FIG. 5 is a block diagram of the main parts of the image forming apparatus. The image forming apparatus is controlled by a CPU 31. CPU3
1 takes in data from sensors S1, S2 to S3, operation panel 34, etc. according to a program stored in ROM 32, and controls main motor 19, clutch 35, etc. according to these data. The clutch 35 connects the driving force of the main motor 19 to the eccentric cam driving force transmission device 18. Further, the amount of rotation of the eccentric cam according to the paper size is stored in area M of the RAM 33, and when adjusting the pressure of the eccentric cam, the CPU 31 extracts data from this and controls the clutch 35 on/off.

FIG. 1 is a flowchart showing a processing procedure related to pressure adjustment of an eccentric cam.

When the manual feed tray 2 or the paper cassettes 3, 4 is selected from the operation panel 34, the cam rotation amount is set according to the size of the receiver seat by referring to the rotation amount data stored in the memory area of the RAM 33. (nl-+
n2). When the image forming process is started and the exposure process is completed, the leading edge of the latent image on the media sheet and the leading edge of the receiver sheet 5 are transported so that they overlap at the pressure development point P2. At this point, the pressure development process begins. The clutch 35 that transmits the driving force to the eccentric cam is turned on, and the eccentric cam l7 rotates by the amount of rotation set in n3 (ni
l-nl4). As a result, the media seat 54 and the receiver seat 5 are pressurized with appropriate pressure, and no wrinkles occur. Then, the pressure rollers 11 and 12 rotate to perform pressure development (n 1 5→nl 6). When the pressure development is completed, the clutch 35 is turned on again to release the pressure on the pressure roller (n17 to n19).

(Effects of the Invention As described above, according to the present invention, the pressure roller is applied with a pressure that corresponds to the paper size, so the pressure roller does not bend, preventing the paper from wrinkling, and improving the image quality. It is possible to prevent pressure drop and jam from occurring.Also, uneven pressure distribution in the axial direction of the pressure roller does not occur.Also, even if the paper size is different, the pressing force is always constant per unit line segment, so A constant color density can be obtained.

[Brief explanation of drawings]

Figure 1 (A). (B) is a flowchart showing the processing procedure of the main part during image formation in the image forming apparatus which is an embodiment of the present invention, FIG. 2(A) is a diagram showing the rotational state of the eccentric cam, and FIG. ) is a diagram showing the relationship between the paper size and the rotation amount of the eccentric cam, and Figure 3 is a cross-sectional diagram of the pressure developing device.
FIG. 4 is an external view of the pressure developing apparatus, FIG. 5 is a block diagram of the main parts of the image forming apparatus, and FIG. 6 is a schematic structural diagram of the image forming apparatus. No. IF (A) 1['7I (B) 1, 12 - Pressure roller, 3, 14 - Holder, 7 - Eccentric cam, 8a to 18d - Gear, 8e - One-way clutch, 9 - Motor, 0 - Sliding Disk, 1.22-slit, 1-position detection sensor, 2-S4-paper size sensor.

Claims (1)

[Claims] (1) A pressure device that presses a pair of pressure rollers, an eccentric cam that adjusts or releases pressure against the force of this pressure device, and a drive force transmission device that transmits driving force to the eccentric cam. In an image forming apparatus equipped with a pressure developing device, the driving force transmission device includes a one-way clutch, a means for inputting the size of the paper passing the pressure roller, and a means for inputting the size of the paper passing the pressure roller, and a means for inputting the size of the paper passing the pressure roller, An image forming apparatus equipped with a pressure developing device, characterized in that it is provided with means for setting the amount of rotation.