JPH0827531B2 - Image forming device - Google Patents

Description

Description: (a) Field of Industrial Application The present invention relates to an image forming apparatus for loading a media sheet, and more particularly to a media sheet conveyance control means for economical use of the media sheet.

(B) Conventional Technology A method of forming an image using a media sheet coated with microcapsules containing a photocurable material and an image-forming agent, and an image-receiving sheet coated with a developing material for developing the color of the image-forming agent is disclosed. It is disclosed in Japanese Patent Publication No. 58-88739. When the media sheet is exposed to the reflected light of the document, the microcapsules exposed to the light are cured, and a selectively cured image (latent image) is formed on the entire media sheet. When the image-receiving sheet is superposed on the selectively cured image and pressed by a pressure roller, the uncured microcapsules are destroyed, the image forming agent flows out, and pressure development is carried out. That is, a color image is formed by reacting with the developing material on the image receiving sheet to form a color.

Until the media sheet is exposed, in order to protect it from exposure to light and destruction of microcapsules due to external force, it is generally wound around a supply shaft in a roll shape and conveyed through an image forming path including an exposure point and a pressure developing unit. After that, it is used and the winding shaft can be wound up. At the time of exposure, with the supply shaft free and the winding shaft stopped, the media sheet is pulled out by a moving roller (buffer roller) provided downstream of the exposure point for pulling out the media sheet. Since the moving speed of the media sheet at the exposure point affects the length of the image in the conveyance direction, it is necessary to keep the speed at which the media sheet passes the exposure point constant in order to faithfully reproduce the image of the original. Yes, the moving roller moves at a constant speed to pull out the media sheet. During pressure development, the supply shaft is locked so that the media sheet is not pulled out, the winding shaft is rotated while the moving roller is returned, and the pulled out portion is wound up, and the end of the latent image on the media sheet is pressed by the pressure roller. Send to. At the same time, the image receiving sheet is fed from the paper feeding unit in alignment with the leading edge of the latent image on the media sheet. When both sheets are aligned by the pressure roller, the supply shaft is unlocked and the pressure roller is pressed to start pressure development. Since the passing speed of the media sheet and the image receiving sheet in the pressure roller affects the image forming state, it is necessary to keep the speed of passing through the media sheet constant in order to keep the image forming state constant. The pressure roller rotates at a constant speed to pass the media sheet. In the pressure development, only the latent image forming area is pressed, and generally, the rear end of the image receiving sheet is detected to release the pressure of the pressure roller, and then the image receiving sheet is peeled from the media sheet. When pressure development is complete, the feed shaft is locked and awaits the next imaging process.

(C) Problem to be Solved by the Invention However, in the above-mentioned image forming process, there is the following problem in locking the supply shaft at the end of pressure development.

The pressure roller is temporarily stopped at the void portion at the rear end of the image receiving sheet, the pressure release of the pressure side roller of the pressure roller is started, and the pressure roller is further rotated to release the media sheet at the peeling section (peeling roller, peeling claw, etc.). And peel off the image receiving sheet. However, immediately before the end of this peeling, the pressure release progresses, the pressing force of the pressure roller and the joining force between the media sheet and the image receiving sheet become weaker than the take-up force of the take-up shaft, and the media sheet is taken up. It will be rolled up extra on the shaft. Therefore, the media sheet in the unexposed portion is offset by the pressure roller, the image quality is degraded, and the inter-image area on the media sheet becomes large, which is against the effective use of the media sheet.

Therefore, an object of the present invention is to provide an image forming apparatus which eliminates waste of a media sheet and improves the image quality.

(D) Means for Solving the Problem In the present invention, the latent image formed by image formation exposure on the media sheet pulled out from the supply shaft is overlapped with the image receiving sheet and passed through a pair of pressure rollers to apply the image. In an image forming apparatus that winds the media sheet around a take-up shaft after performing pressure development by applying pressure, a rotation speed detecting unit that detects a rotation speed of the supply shaft, and the rotation speed detecting unit includes the pressure developing unit. Supply shaft locking means for locking the rotation of the supply shaft when a rapid increase in the rotation speed is detected in comparison with the rotation speed when the media sheet passes between the pressure rollers together with the image receiving sheet. It is characterized by

(E) Operation FIG. 1 is a block diagram of the present invention. Media sheet
106 and the image receiving sheet 107 are overlapped with each other, the pressure roller
The pressure is applied by 104 to perform pressure development. When this pressure development is completed, that is, when the rear end of the image receiving sheet 107 passes the pressure roller 104, the pressure release of the pressure roller is started and the image receiving sheet 107 is peeled from the media sheet 106. When the pressure is released to some extent, the pressure roller 104
The winding force of the winding shaft 105, which has been set in accordance with the pressing force and the joining force of the image receiving sheet, becomes excessive, and the rotation speed of the winding shaft 105 increases. Then, the media sheet 106 is also pulled out faster than before, and the rotation speed of the supply shaft 102 sharply rises as compared with the rotation speed when the media sheet 106 passes through the pressure roller 104 together with the image receiving sheet 107. The rotation speed detection means 101 attached to the supply shaft 102 detects this rise, and the supply shaft lock means 100 locks the supply shaft 102 by this detection signal.
Therefore, the media sheet is not wound up excessively, the unexposed portion is not sandwiched between the pressure rollers, offset is prevented, and the media sheet can be effectively used.

(F) Embodiment FIG. 5 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

A document table 2 is arranged on the upper surface of the main body 1, and an optical device 3 including a light source, a mirror, and a lens is arranged on the upper portion of the main body 1. At the lower right portion of the main body 1, there is provided a paper feed section 4 for feeding the image receiving sheets 41 one by one from a cassette or a manual paper feed table. Media sheet 51 wound around supply shaft 53
The media cartridge 5 for storing the media is mounted in the center of the main body 1 at a slightly left portion. A disk 11 having a large number of slits 12 is fixed to the supply shaft 53, and the disk 11 has a supply shaft 53.
Rotates with the rotation of. The transmissive optical sensor 13 detects the rotational speed of the supply shaft 53 by counting the slits 12 of the rotating disk 11, and in this embodiment, the disk 11 and the transmissive optical sensor 13 detect the rotational speed detecting means 10. Make up. From the outlet of the media cartridge, tractor roller 61 and exposure plate 6
2, guide roller 63, buffer roller 64, pressure roller 6
5, 66 are arranged in the conveyance path of the media sheet up to the winding shaft 54. A glossing device 7 is provided below the mounting position of the media cartridge 5, and a paper output unit 8 is provided on the left side of the main body 1.
Is provided.

 Next, an image forming operation will be described.

The optical device 3 scans a document placed on the document table 2. At this time, the buffer roller 64 is moved in the direction of arrow A, and the reflected light of the document is applied to the media sheet 51 on the exposure plate 62 to perform slit exposure. The exposure cures the microcapsules on the media sheet to form a selectively cured image.

When the exposure is over, the rotation of the supply shaft 53 is locked and the winding shaft
54 is rotated, the buffer roller 64 is moved in the direction of arrow B, and the area where the selectively cured image is formed on the media sheet is conveyed to the pressure developing section 6. On the other hand, the image receiving sheet 41 is sent to the pressure developing section 6 in time with the leading edge of the selectively cured image on the media sheet. The leading edge of the selectively cured image on the media sheet and the leading edge of the image receiving sheet 41 are pressure rollers 65, 66.
When they are aligned, the supply shaft 53 is unlocked, the pressure roller is pressed and rotated, and development is performed while being conveyed by the conveying force of the pressure roller. When the rear end of the image receiving sheet 41 passes through the pressure roller, the pressure roller 65 is once stopped and the pressure release is started, and then the pressure roller is rotated again until the image receiving sheet 41 is separated from the media sheet 51. When the pressure is released to some extent, the winding becomes free, the winding speed increases, and the rotation of the supply shaft 53 also increases. Therefore, the disk 11
The number of pulses per unit time output from the transmission type optical sensor 13 counting the slits 12 of the above is compared with the number of pulses per unit time when the media sheet 51 is passing through the pressure roller 65 together with the image receiving sheet 41. And then increase sharply. When the rotation speed detecting means detects this change, the rotation of the supply shaft 53 is locked. As a result, the media sheet 51 is not wound up extra.

The pressure-developed media sheet is rewound to the vicinity of the exposure point at the rear end of the image forming area for effective use.
On the other hand, the peeled image receiving sheet is conveyed to the glossing device 7,
After being subjected to heat treatment or the like, it is discharged to the paper discharge unit 8.

FIG. 4 is a block diagram of a part of the control unit of the image forming apparatus.

ROM71, RAM72 are connected to CPU70, and via I / O73,
A control circuit 74, a main motor drive circuit 76, and a supply shaft lock mechanism 79 are connected. A main motor 77 is connected to the main motor drive circuit 76, clutches C1, C2 and C3 are connected to the control circuit 74, and pressure rollers 66 and a take-up shaft 54 are connected to the clutches C1, C2 and C3, respectively. The rotation of the main motor 77 is transmitted to the supply shaft 53 and the pressure release cam 78.

The rotation speed detecting means 10 is attached to the supply shaft 53, the detected pulse number is output to the I / O 73, and the CPU 70 monitors the pulse number. The CPU 70 controls the entire image forming apparatus, and a control program is written in the ROM 71 in advance. Other working areas such as timers and counters are assigned to the RAM 72. The pressure development is performed by locking the supply shaft. Further, when the pressure development is completed, when the CPU 70 takes in the detection signal of the pressure roller passage at the rear end of the image receiving sheet such as a sensor (not shown) by the CPU 70 through the I / O 73, the off signal to the clutch C1 is set to the I / O 73. Output via the pressure roller 66 and the rotation of the winding shaft 54 is stopped. Then clutch
An ON signal is output to C3 to activate the pressure release cam 78.
After that, an ON signal is output to the clutch C1 via the I / O 73 to rotate the pressure roller 66. When the pressure release progresses in this way, the pulse output of the rotation speed detection means of the supply shaft 53 rapidly increases. Then, the CPU 70 outputs an ON signal to the supply shaft lock mechanism 79 as an I / O 73 to lock the rotation of the supply shaft 53. The supply shaft lock mechanism 79 has, for example, a one-way clutch provided in a transmission mechanism from the main motor 77 to the supply shaft 53.

FIG. 3 is a time chart at the end of pressure development in the image forming apparatus.

From the top, the operation of the pressure roller, the pressure release operation, the operation of the winding shaft, the pulse train of the supply shaft, and the lock state of the supply shaft are shown. At time t ₁ , the passage of the rear end of the image receiving sheet of the pressure roller is detected, the pressure roller is temporarily stopped, and the pressure release of the pressure roller on the pressure side is started. At time t ₂ , the pressure is released and the conveyance of the media sheet becomes free, and the joining force between the media sheet and the image receiving sheet becomes weak. Therefore, the winding force of the winding shaft speeds up the winding of the media sheet, and the pulse output of the rotation speed detecting means of the supply shaft rapidly increases. At this point, the supply shaft is locked and the conveyance of the media sheet is stopped.

FIG. 2 is a flowchart of a lock operation of the supply shaft of the image forming apparatus.

When the power is turned on, first, each part is initialized (n1), and the print switch is waited to be pressed (n2). When the print switch is pressed, the supply shaft is freed (n3), and at the same time, the buffer roller starts moving (n4). This causes the buffer roller to pull out the media sheet and perform exposure (n5). When the exposure is completed, the supply shaft is locked (n6), and then the buffer roller starts to return (n7) and at the same time the winding shaft is rotated (n6).
8). On the other hand, when the image receiving sheet reaches the pressure roller (n
9) Stop the buffer roller and winding shaft (n10, 11), unlock the supply shaft to make it free (n12), and start pressing the pressure roller (n13). The pressure roller and the winding shaft are rotated (n14, 15), the return of the buffer roller is continued (n16), and pressure development is started (n17).
When the buffer roller moves to the home position (n1
8) It is stopped (n19), and when the pressure development continued during this period is completed (n20), the pressure roller and the winding shaft are stopped (n21, 22). In this state, pressure release of the pressure roller is started (n23), and then the pressure roller is further rotated (n2
Four). When the pressure release progresses and the conveyance of the media sheet becomes free at the pressure roller section (detected by the change in the pulse output of the rotation speed detection means) (n25), the supply shaft is locked (n25)
26). At this time, the pressure roller is stopped (n27) to completely stop the conveyance of the media sheet. As a result, the pressure release progresses, the pressure contact force of the pressure roller and the joining force with the image receiving sheet weaken, and even if the media sheet becomes free to be conveyed by the pressure roller section, the take-up shaft winds the media sheet excessively. Prevent taking. After that, in order to effectively use the media sheet, a reverse feeding process is performed such as freeing the winding shaft and reversing the feeding shaft (n28), and waits for the press of the print switch for the next image forming operation.

With the above configuration, n25 and n26 correspond to the supply shaft locking means of the present invention.

In the present embodiment, the slitted disc and the transmission type optical sensor are used as the rotation speed detecting means of the supply shaft, but other means may be used.

(G) Effect of the Invention As described above, according to the present invention, since the supply shaft is provided with the rotation speed detecting means and the supply shaft locking means, the pressure is released after the trailing edge of the image receiving sheet is passed at the end of pressure development. When the conveyance of the media sheet becomes free in the pressure roller section, the winding speed sharply increases and the rotation speed of the supply shaft changes, and the rotation speed detection means detects the rotation speed. Lock the supply axis. This allows
At the end of pressure development, do not carry an extra media sheet,
Stop exactly. Therefore, it is possible to prevent the offset of the unexposed portion of the media sheet to the pressure roller and the waste of the media sheet, which in turn improves the quality of the image.
We were able to effectively utilize the media sheet.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention. FIG. 2 is a flowchart of the lock operation of the supply shaft of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a time chart when the pressure development of the image forming apparatus is completed. FIG. 4 is a block diagram of a part of the control unit of the image forming apparatus. FIG. 5 is a schematic configuration diagram of the image forming apparatus. 10 ... Rotational speed detecting means, 11 ... Disc, 12 ... Slit, 13 ... Transmissive optical sensor, 51 ... Media sheet, 53
…… Supply shaft, 54 …… Winding shaft, 65,66 …… Pressure roller.

Claims (1)

[Claims] 1. A pressure developing process is carried out by passing a pressure between a pair of pressure rollers in a state where an image receiving sheet is superposed on a latent image formed by image forming exposure on a media sheet pulled out from a supply shaft, In an image forming apparatus that winds the media sheet around a take-up shaft, a rotation speed detecting unit that detects a rotation speed of the supply shaft, the rotation speed detecting unit, and the media sheet together with the image receiving sheet and the pressure roller during the pressure development. An image forming apparatus comprising: a supply shaft locking unit that locks the rotation of the supply shaft when a rapid increase in the rotation speed is detected as compared with the rotation speed when passing through the space.