JPH02234172A - Pressure relaxing method for image forming device - Google Patents

Abstract

PURPOSE:To allow an image receiving sheet to smoothly pass through a pressurizing position by relaxing the pressure of a pressure roller when the image receiving sheet enters and passes the pressurizing position. CONSTITUTION:A media sheet 4 where a selective setting image is formed and the image receiving sheet 14a, etc., are carried to the pressurizing position P2 and are pressurized by the pressure rollers 16a and 16b. When the image receiving sheet 14a enters the pressurizing position P2, the pressure in the pressurization position P2 is temporarily relaxed after the elapse of a first prescribed time on the basis of the rotation starting time of a timing roll 5. And when the trailing edge part of the image receiving sheet 14a passes through the pressurizing position P2, the pressure in the pressurizing position P2 is temporarily relaxed after the elapse of a second prescribed time since the trailing edge part passed through a sensor S1. Thereby the image receiving sheet 14a can smoothly pass through the pressurizing position P2.

Description

DETAILED DESCRIPTION OF THE INVENTION (al Industrial Field of Application) This invention relates to an image forming apparatus that obtains an image by pressing an image receiving sheet together with a media sheet. The present invention relates to a method for relaxing pressure in an image forming apparatus.

(b) Prior Art As disclosed in JP-A-58-88739, a media sheet coated with microcapsules containing a colorless dye and a photocurable material, and an image receiving material coated with a developing material that develops color from the colorless dye. There is an image forming apparatus method in which a sheet is pressed at a pressing position. In this image forming method, a media sheet is exposed to an original image and then pressed together with an image receiving sheet. When an original or manuscript image is exposed to light on a media sheet, the microcapsules in the portions exposed to the light are hardened, and a selectively hardened image is formed on the media sheet. When this is overlapped with an image-receiving sheet and pressurized, the uncured microcapsules on the media sheet are destroyed, and the colorless dye leaks onto the image-receiving sheet. The leaked colorless dye causes a color-developing reaction with the developing material on the image-receiving sheet, and an image can be obtained on the image-receiving sheet. In order to obtain a good image in such an image forming method, it is necessary to prevent the microcapsules coated on the surface of the media sheet from being destroyed by the action of external force before the media sheet passes through the pressurizing position. The capsule must have sufficient strength even in its uncured state. For this reason, it is necessary to apply a sufficiently large pressure to the media sheet and image receiving sheet at the pressurizing position, and generally a pair of pressure rollers that make up the pressurizing position apply a linear pressure of about 90 kg/cm. It's in contact. (Problems to be Solved by the Cl Invention Since the media sheet on which the selectively cured image is formed is no longer needed after passing the pressurizing position, it is constructed in a long shape and is always positioned between the pressure rollers. However, since an image is formed on one image-receiving sheet at a pressurized position and is used directly after being ejected from the apparatus, it is desirable that the image-receiving sheet be cut into a size corresponding to the size of the image. If this cutting process is performed after passing through the pressure position, a cutting device must be installed in the image forming apparatus, which increases the size and cost of the apparatus. A cut sheet-shaped image receiving sheet cut to standard dimensions is used, and during image forming work, this cut sheet-shaped image receiving sheet passes through a pressurizing position one by one.However, as mentioned above, Since the pressure rollers are in contact with a large amount of pressure, in order to pass an image-receiving sheet with a certain thickness, the distance between the pair of pressure rollers must be increased by the thickness of the image-receiving sheet. It is difficult to smoothly insert the front end of the image receiving sheet between the rollers while applying a predetermined pressure to the pressure roller, and depending on the condition of the front end of the image receiving sheet, a jam may occur.Also, When the image-receiving sheet passes through the pressure position, the distance between the pressure rollers becomes narrower by the thickness of the image-receiving sheet.
At this time, if a predetermined pressure is applied to the pressure roller, both rollers will come into contact with a large pressing force across the media sheet,
Generates noise. As described above, when the image-receiving sheet passes through the pressure position, if the pressure applied to the pressure roller is kept constant, there is a problem in that the image-reception sheet cannot be smoothly passed through the pressure position.

The purpose of this invention is to reduce the pressure of the pressure roller when the image receiving sheet enters the pressurized position and when it passes through this, thereby preventing the occurrence of a jam when the image receiving sheet enters the pressurizing position and applying pressure. It is an object of the present invention to provide a pressure relief method for an image forming apparatus that can prevent the generation of noise when passing through a position and allow an image receiving sheet to smoothly pass through a pressurized position.

(d) Means for Solving the Problems The pressure relief method for the image forming apparatus of the present invention is such that the image-receiving sheet is placed between the sheet feeding section and the pressurizing position, rotates at a fixed timing after feeding the sheet, and presses the image-receiving sheet. timing roller that leads to the pressure position,
and a sensor that detects the passage of the rear edge of the image receiving sheet.
In an image forming apparatus that presses an image-receiving sheet and a media sheet that has passed through an exposure position at a pressurizing position, a first time period is defined as the time during which the image-receiving sheet moves from the timing roller to the pressurizing position after the timing roller starts rotating. When a predetermined time has elapsed, the pressure at the pressurizing position is temporarily relieved, and after that, the sensor detects passage of the trailing edge of the image receiving sheet, and a second predetermined time is defined as the time during which the image receiving sheet moves from the sensor to the pressurizing position. It is characterized by temporarily relieving the pressure at the pressurized position when time has elapsed.

(el effect) In this invention, the front and rear ends of the timing sheet pass through the pressurized position while the pressure at the pressurized position is temporarily relieved. Therefore, the front end of the image receiving sheet The reaction force required to enter the pressurized position is small, and the image receiving sheet smoothly enters the pressurized position.Furthermore, the pressure acting on the pressurized position when the image receiving sheet passes through the pressurized position is alleviated. , does not generate large noise.

if) Embodiment FIG. 2 is a schematic front sectional view showing the configuration of an image forming apparatus to which the pressure relief method of the present invention is applied.

A cartridge 1 containing a roll-shaped media sheet 4 is installed inside the image forming apparatus main body 10 .

The media sheet 4 is transferred from this cartridge l to the roller 17.
．． 18 rotation, the pressurization position P passes through the exposure position P1.
2. This pressurizing position P2 is located between a pair of pressure rollers 1
6a and 16b. The media sheet 4 that has passed through the pressurizing position P2 is wound up on the winding shaft 7. On one side of the image forming apparatus main body 10, there are image receiving sheets 14a. Paper cassette 13a containing lb. 13b is installed.

Image receiving sheet 14a. 14b is paper feed roller 15a, 15b
The rotation of the paper feeds the paper one by one. Paper cassette}13a
, 13b, and the pressurizing position P2 are provided with a sensor S1 and a timing roller 5. Image receiving sheet l4a fed from paper feeding section 19
<14b) comes into contact with the timing roller 5 with its front end and stops. The timing roller 5 starts rotating at a predetermined timing and guides the image receiving sheet 14a (14b) to the pressurizing position P2. Further, the sensor S1 is connected to the image receiving seat 14a.
(14b) Detects passage of the rear end.

A conveyor belt 20 and a glossing device 2l are provided on the left side of the pressurizing position P2. The conveyor belt 20 is at the pressurizing position P
The image receiving sheet 14a (14b) that has passed through the image forming apparatus 2 is guided to a glossing device 2l. The glossing device 21 is attached to the image receiving sheet 14a (
14b) is heated. The image receiving sheet that has passed through the glossing device 21 is discharged onto a discharge tray 22. Sensor S2 detects that the image receiving sheet 1-142 (14b) is ejected.

A document table 11 made of hard transparent glass is provided on the top surface of the image forming apparatus main body 10 . An optical system device 12 consisting of a light source 23, mirrors 24 to 27, and a lens 28 is provided on the lower surface of the document table 11. This optical system device
2, the light source 23 and mirrors 24 to 26 are located on the document table 11.
It moves back and forth on the lower surface of the document table 11 to scan the image of the document placed on the document table 11. The light from the light source 23 is reflected on the image surface of the original, and is distributed to the exposure position P1 via mirrors 24 to 27 and a lens 28, as shown by the dashed line in the figure.

In the image forming apparatus 10 configured as described above, the light source 2
A selectively cured image is formed on the surface of the media sheet 4 by exposure to the reflected light from the original document. The image receiving sheet 1 together with the media sheet 4 on which this selectively cured image is formed
4a (14b) is conveyed to the pressing position P2, and the pressure rollers 16a. 16b. This pressure destroys the uncured microcapsules on the media sheet 4, and the colorless dye leaked from the microcapsules causes a coloring reaction with the developing material on the image receiving sheet 14a (14b). ) to get the image. The image receiving sheet 14a (14b) is coated with a thermoplastic resin together with a developing material, and this thermoplastic resin is heated and melted by the glossing device 21, thereby imparting gloss to the image. After this, the image receiving sea}14a (14
b) is discharged onto the discharge tray 22.

FIG. 1 is a diagram showing a pressure roller 16 that constitutes a pressure roller pressure position in the image forming apparatus.
a. 16b is pivotally supported by the upper frame 31 and the lower frame 32. The upper frame 31 is fixed to the image forming apparatus main body 10. lower frame 3
2 is rotatable about a fulcrum 33 with respect to the upper frame 3l. The elastic force of a spring 34 acts on this lower frame 32 in the direction of arrow A, and the pressure roller 16b abuts against the pressure roller 16a with a predetermined linear pressure.

A lift mechanism 37 is provided between the upper frame 31 and the lower frame 32. The rotation of the pressure release motor M1 is transmitted to the lift mechanism 37 via a worm roller 38b and a worm gear 38a. When the pressure release motor M1 rotates forward or reverse, the interval between the upper and lower links of the lift mechanism 37 expands and contracts. Therefore, the pressure release motor M1
When it rotates forward, the lower frame 32 moves in the direction of arrow B against the elastic force of the subring 34, and the pressure rollers 16a and 1
6b decreases. Conversely, when the pressure roller release motor M1 reverses, the lower frame 32 moves in the direction of arrow A due to the elastic force of the spring 34, and the pressure roller 1 is moved in the direction of arrow A.
6a. The linear pressure acting on 16b increases.

FIG. 3 is a block diagram showing a part of the control section of the image forming apparatus.

The CPU 4 1 is connected to the sensor S 1 . The detection data of S2 is input. CPU4
A program that defines the operation of the CPU is written in advance in the ROM 42 connected to the CPU 4 1, and the CPU 4 1 controls the clutch driver 45 and the motor driver 46 via the ■/0 interface 44 according to this program.
Outputs control data to. Clutch driver 45 drives paper feed roller clutch 47 and timing roller clutch 48 according to this control data. Motor driver 46 similarly drives pressure release motor M1 according to the control data. Furthermore, the memory area MAL of the RAM 43 connected to the CPU 41 is allocated to a timer T, which will be described later. FIG. 4 is a flowchart showing a part of the processing procedure of the control section of the image forming apparatus, and shows the processing procedure of pressure control of the pressure roller pressing mechanism shown in FIG. A main motor (not shown) is driven by operating the print switch. Next, the paper feed roller clutch 47 is driven at a predetermined timing (nl), and the rotation of the main motor is transmitted to the paper feed roller 15a (15b). The rotation of this paper feed roller 15a (15b) causes the image receiving sheet 14a (
14b) is fed. The fed image receiving sheet 14a (
14b) is detected by the sensor S1 (n2) and starts the timer T assigned to the memory area MAL (n3). At this time, the timing roller 5 is not yet rotating and the fed image receiving sheet is The motor 14a (14b) stops with its front end in contact with the timing roller 5. On the other hand, although the rotational force of the main motor is transmitted to the paper feed roller 15a (15b), the rotation is stopped due to the frictional resistance received from the stopped image receiving sheet 14a (14b). The image receiving sheet 14a
(14b) is urged in the direction of the timing roller 5. When timer T measures time T1, paper feed roller clutch 4
7 and timing roller clutch 48.
Turn on (n4 to n6). The timing roller 5 starts rotating by driving the timing roller clutch 48,
The image receiving sheet 14a (14b) is conveyed to the pressurizing position P2. Furthermore, when timer T measures time T2, time T
, the pressure release motor M1 rotates forward (n
7-n9). That is, when time (Tt - T+) has elapsed after the timing roller 5 started rotating, the pressure release motor M1 rotates forward, and the pressure at the pressurizing position P2 decreases. This time (Tx - Tt) is the timing roller 5
This is the time until the front end of the image receiving sheet 14a (14b) reaches the pressurizing position P2 after the start of 0 rotation, and is the first predetermined time of the present invention. Also, the time period during which the pressure release motor M1 is rotating in the normal direction (Ts - T*) is the time when the image receiving seat L4a
(14b) at the front end of the pressure roller 16a. Pressurize position P as much as necessary to allow smooth passage between 16b and 16b.
This is the time during which the pressure of 2 can be reduced.

When the timer T measures the time T, the pressure release motor M2 is reversed until the time T.
). Reverse rotation time of this pressure release motor M2 (T4 - Ts
) is made equal to time (T3-Tz). Therefore, when the time T4 has elapsed, the pressure at the pressurizing position P2 has returned to a pressure sufficient to destroy the uncured microcapsules coated on the media sheet 4. As a result, the image receiving sheet 14a (14b) is pressed together with the media sheet 4 at a predetermined pressure.

Thereafter, when the rear end of the image receiving sheet 14a (14b) passes the sensor S1, the contents of the timer T are cleared (nl2.
nl3), when the timer T measures the predetermined time T, the time T
．． Rotate the pressure release motor Ml in the forward direction until (n14 to n16)
). This predetermined time T,
This is the time required for the rear end to reach the pressurizing position P2 from the position of the sensor S1, and is the second predetermined time of the present invention.
By rotating the pressure release motor M1 in the forward direction in this manner, the pressure at the pressurizing position P2 can be reduced when the rear end portion of the image receiving sheet 14a (14b) passes through the pressurizing position P2. can. When the rear end of the image receiving sheet 14a (14b) passes through the pressing position P2, the lower pressure roller 16b
moves upward by the thickness of the image receiving sheet 14a (14b), but the normal rotation of the pressure release motor M1 makes it possible to reduce the force acting on the pressure roller 16b at this time, thereby preventing the generation of large noise. be able to.

Timer T is set to time T. , the pressure release motor M1 is reversed until time T (nl6 to nl
8). According to this embodiment, the image receiving sheet}14a (14
b) enters the pressurized position P2, the pressure at the pressurized position can be temporarily relieved after a first predetermined time has elapsed based on the start of rotation of the timing roller 5, and the image receiving sheet 14a (14b) can be smoothly entered into the pressurizing position P2. Moreover, the image receiving sheet 14a (
14b) When the rear end portion of the image receiving sheet 14a (14b) passes through the pressurizing position P2, the rear end portion of the image receiving sheet 14a (14b) passes the sensor S1 and then returns to the pressurizing position when a second predetermined time has elapsed. The pressure of P2 can be temporarily relieved, and the pressure roller 16a
By reducing the contact force between and 16b, generation of large noise can be prevented.

Furthermore, the timing roller 5 and the sensor S1 are at the pressure position i.
It is provided close to tP2, and the image receiving seat 14a
Since it is possible to prevent errors in the positions of the front and rear ends due to the deflection of the image receiving sheet 14a ( 14b) can always be smoothly passed to the pressurizing position P2. Further, the timing at which the front end and the rear end of the image receiving sheet 14a (14b) pass through the pressurizing position P2 is determined based on the timing at which the front end and the rear end pass through a predetermined position. Therefore, even if the size of the image receiving sheet changes, there is no need to change the time measured by the timer T, and the pressure at the pressurizing position can be easily controlled.

+g＞Effect of the Invention According to the present invention, when the front and rear ends of the image receiving sheet 14 pass through the pressurizing position, the pressure at the pressurizing position can be relieved, and the image receiving sheet can be smoothly moved. It can be passed to a pressurized position. Furthermore, the timing to relieve the pressure at the pressurized position is determined based on the start of rotation of the timing roller near the pressurized position and when the sensor detects the rear end of the image receiving sheet, so the pressure is always applied at accurate timing. The pressure will not be relaxed when the image forming area is shortened or there is no image receiving sheet at the pressure position. FIG. 1 is a diagram showing a pressure roller pressing mechanism of an image forming apparatus to which the pressure relief method of the present invention is applied, FIG. 2 is a schematic front cross-sectional view showing the configuration of the image forming apparatus, and FIG. FIG. 4 is a block diagram of the main parts of the control section of the image forming apparatus, and is a flowchart showing a part of the processing procedure of the control section of the image forming apparatus.

One Mede. Iacito, one timing roller, 4a (14b) - image receiving sheet, 91 paper feed section, 1- exposure position, 21 pressurized position; 1-Sensor.

Claims (1)

[Claims] (1) A timing roller located between the paper feed section and the pressure position, which rotates at a fixed timing after paper feeding to guide the image receiving sheet to the pressure position, and a sensor that detects passage of the trailing edge of the image receiving sheet. In an image forming apparatus that presses an image-receiving sheet and a media sheet that has passed through an exposure position at a pressurizing position, the image-receiving sheet is provided with a time period during which the image-receiving sheet moves from the timing roller to the pressing position after the timing roller starts rotating. When the first predetermined time has elapsed, the pressure at the pressurizing position is temporarily relieved, and after that, the sensor detects passage of the trailing edge of the image receiving sheet, and a second period is the time during which the image receiving sheet moves from the sensor to the pressurizing position. 1. A method for relieving pressure in an image forming apparatus, comprising temporarily relieving pressure at a pressurizing position when a predetermined period of time has elapsed.