JPH05165183A - Heat developing device - Google Patents

Abstract

PURPOSE:To stably and uniformly heat a photosensitive member and to obtain an image with high quality by providing a specified photosensitive member interposing means which interposes the photosensitive member between heating parts near a heating start position. CONSTITUTION:A photosensitive member 8 is pinched by a nip roller 44 and a heating roller 41 at the heating start position of the roller 41 so that the side thereof coated with a microcapsule is brought into contact with the roller 44. Then, the roller 44 is the hard roller made of metal, resin or hard rubber. In the case of the hard roller, the roller 41 itself is hardly deformed even when the member 8 is pressed to the roller 41. There fore, the peripheral speed of the roller 44 rotated in accordance with the carrying of the member 8 becomes almost identical to the carrying speed of the member 8 at a contact part with the member 8. In such a manner, when the relative speed of the member 8 and the photosensitive member pinching means at the contact part is zero, the photosensitive substance coating surface of the member 8 is not rubbed and an image is not damaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat developing apparatus of an image forming apparatus for forming an image on a copying machine or a printer using a heat developing material.

[0002]

2. Description of the Related Art A wide variety of image forming methods and apparatuses are known, and a conventional example of an image forming apparatus using a heat developing material is, for example, a photosensitive transfer type heat developing material. No. 62-147461 can be mentioned. According to this publication, the exposure unit, the thermal development unit,
A main mechanism portion such as a pressure transfer portion is formed inside one constituent body, and image formation is performed by the following procedure.

First, a roll-shaped photosensitive transfer type heat-developable material is cut into a predetermined length and then imagewise exposed to form a latent image. Next, thermal development is performed with a heating roller. After that, the photosensitive member and the image receiving paper are superposed and pressure-transferred by the roller, and the photosensitive member is transferred to the photosensitive material discarding section by the separating device.
The image receiving paper is discharged to the tray via the fixing device.

In the heat developing apparatus, a part of the peripheral surface of the heating roller is orbited by an endless belt, and a photosensitive member is sandwiched and conveyed between the heating roller and the endless belt for thermal development.

Further, in the conventional example of the heat developing device disclosed in Japanese Patent Application No. 3-217157, the photosensitive member is wound around a heating roller so that only the back surface of the photosensitive member which is not coated is heated. ..

[0006]

However, the above-mentioned prior art has a problem that it is not possible to easily achieve both stable output image density and high-quality image without density unevenness. ..

First, in the method of heat-development by sandwiching a photosensitive member between an endless belt and a heating roller, the density is lower as the ambient temperature is higher even though the heating roller is controlled at a constant temperature. It was observed that the concentration became lower as time passed. This is because the endless belt is the surrounding environment,
This is because the thermal development state changes due to temperature fluctuations due to heat conduction from the heating roller. In addition to the complicated structure of the endless belt itself, if the temperature of the endless belt is always kept constant, it becomes a very complicated and expensive device.

On the other hand, in the heat developing apparatus of the type in which only one surface is brought into contact with the heating roller for heating, a stable image density can be obtained with a simple apparatus configuration. This is because the temperature of the photosensitive member during the thermal development can be accurately maintained by not touching any member other than the heating roller whose temperature is appropriately controlled in the thermal developing section.

However, in the above method, there are cases where unintended density unevenness occurs on the image. The inventor
It has been discovered that the cause of the above-mentioned density unevenness is due to the instability of the contact start position of the photosensitive member to the heating portion of the heat developing device. That is, the photosensitive member often uses a resin film such as polyethylene terephthalate or paper as a base material, and is thermally sized by being heated. As a result, the width of the photosensitive member is different between the portion in contact with the heating portion of the heat developing device and the portion not heated before the heating portion. Then, the width of the photosensitive member abruptly changes at the contact start position to the heating unit of the thermal developing device which is the boundary, and as a result, the photosensitive member in front of the heating unit floating in the air undulates. When the corrugated photosensitive member comes into contact with a heating part such as a cylindrical shape, the contact start position is different between the crests and troughs of the wave, which causes a difference in heating time and unevenness in heat development. Caused uneven density. Further, in a remarkable case, the corrugation of the photosensitive member may enter into the heating portion and float at all from the heating portion, resulting in a portion which is not subjected to thermal development, resulting in remarkable deterioration of image quality.

The present invention solves the above problems in view of such a situation, and an object of the present invention is to stably obtain a high quality image by heating the photosensitive member stably and uniformly. The heat developing device of the image forming apparatus can be simply
It is to provide it at a low price.

[0011]

The heat developing apparatus of the present invention comprises:
A method of heating a photosensitive member mainly by contacting from one side surface, and having a photosensitive member clamping means for clamping the photosensitive member between the heating parts at a relative speed of substantially 0 near a heating start position. In particular, it is preferable that the photosensitive member holding means is a hard roller.

[0012]

EXAMPLES The heat developing apparatus of the present invention and the image forming apparatus using the same will be described in detail below with reference to Examples.

FIG. 1 is a front sectional view of a copying machine using a heat developing apparatus according to an embodiment of the present invention. First, the operation of the copying machine will be described.

A document 2 is placed on a document table 1 movably provided in the direction of arrow A in the figure, and light beams emitted from a red lamp 3, a green lamp 4 and a blue lamp 5 which are light sources are emitted from the document 2. And the reflected light from the original 2 is imaged on the photosensitive member 8 that moves on the exposure table 7 through the lens 6 to form a so-called scan exposure system.

A continuous sheet-shaped photosensitive member 8 sent out from a cartridge 20 containing an unexposed photosensitive member 8.
After being exposed on the exposure table 7 to form a latent image, it is heated and developed by the heat developing device 40 having the nip roller 44, which is the photosensitive member holding means of the present invention, via the conveying roller 9. On the other hand, the cut-sheet-shaped transfer member 11 stored in the paper feed tray 10 is sent out by the paper feed device 12 and is synchronized with the image area formed on the photosensitive member 8 so that the photosensitive member 8 is synchronized.
And a pressure transfer device 60 of a roller pressure type is pressure-transferred. The pressure unit of the pressure transfer device 60 is composed of three rollers, an upper roller 61, a middle roller 62, and a lower roller 63, and pressure transfer is performed between the upper roller 61 and the middle roller 62.

After this, the transfer member 11 is separated from the photosensitive member 8 by the separating roller 64 and is discharged to the paper discharge tray 14 through the conveying roller 13. The photosensitive member 8 is pinched to promote the conveying and separation of the photosensitive member 8. It is wound around the winding shaft 21 via the roller 65.

Reference numeral 15 is a manual sheet feeding port, and 16 is a gas filter for removing gas generated in the machine.

Next, one embodiment of the heat developing apparatus of the present invention will be described in detail.

FIG. 2 is a thermal developing device 4 of the image forming apparatus of FIG.
It is the perspective view which showed 0. The photosensitive member 8 is the heating roller 4
Nip roller 4 so that the side coated with the microcapsule comes into contact with nip roller 44 at the heating start position 1.
4 and the heating roller 41. Further, in a region other than the heating start position, the heating roller 4 having a heating peripheral surface so that the side on which the microcapsules are not applied comes into contact.
Each of them is wound by a predetermined amount, and is heated while being conveyed while being given a tension. Heating roller 41
Both ends are rotatably supported by bearings 42.
Further, the heating roller 41 has a halogen lamp heater 43 inside the cylinder, and the heating peripheral surface is about 120 ° C to 16 ° C.
The heating amount is appropriately controlled so as to be constant at a predetermined temperature between 0 ° C. The nip roller 44 is rotatably attached to a lever 46 that is swingable around a rotation shaft 49 attached to a frame (not shown). The lever 46 is biased toward the heating roller 41 by a spring 45. The spring 45 has one end fixed to a frame (not shown) and the other end fixed to a lever 46.

The nip roller 44 is a hard roller made of metal, resin, hard rubber or the like. For hard rollers,
Even if the heating roller 41 is pressed through the photosensitive member 8, the roller itself is hardly deformed. Therefore, the photosensitive member 8
The peripheral speed at the contact portion of the nip roller 44 that rotates following the conveyance of the photosensitive member 8 with the photosensitive member 8 is almost the same as the conveying speed of the photosensitive member 8. When the relative speed at the contact portion between the photosensitive member 8 and the photosensitive member holding means is apparently present, the surface of the photosensitive member 8 on which the photosensitive member is coated is abraded, which may cause scratches on the image. In the photosensitive transfer type image forming apparatus using the microcapsules described in this embodiment,
When the surface of the photoconductor is rubbed, the microcapsules will be destroyed by a contact pressure much smaller than the pressure applied in the vertical direction, and the ink will be transferred from the part that should not be transferred due to curing. become. For example, if the nip roller 44 is fixed so that it cannot rotate, a fine black line will appear on the image even if the nip roller 44 is pressed with a slight surface thickness. Even when the nip roller 44 is rotatable, the surface of the photoconductor may be damaged when the roller is deformed by pressing. This is because the roller is deformed in the cross-sectional direction by being pressed, but the nip roller 44 is kept constant during the period from when the photosensitive member 8 approaches the nip portion to when the photosensitive member 8 passes the maximum surface pressure and leaves the nip portion. The speed of the roller surface is not constant because the radius of the contact point changes due to the deformation despite the rotation at the rotation speed. Therefore, the surface of the nip roller 44 and the photosensitive member 8
Therefore, a relative speed is generated between the two, and the surface of the photosensitive member 8 is slightly rubbed to destroy the microcapsules. If the nip roller 44 is composed of a hard roller, there is no fear of causing such a problem.

When a hard roller is used as the nip roller 44, the scratches on the image due to the surface abrasion of the photosensitive member 8 do not occur, but if the pressing force against the heating roller 41 is increased too much, the surface pressure becomes high. If it passes, the microcapsules will be destroyed and fogging will occur in the low-density portion on the image. According to experiments conducted by the present inventor, fogging occurred when the nip roller 44 was pressed with a linear pressure of about 100 gr / cm or more. It is necessary to determine the biasing force of the spring 45 so as not to exceed this range.

Next, the arrangement position of the nip roller will be described. FIG. 3 shows a nip roller 44 and a heating roller 41.
It is sectional drawing which showed the positional relationship. In the present invention, the nip roller 44 needs to be arranged in the vicinity of the heating start position. However, according to an experiment conducted by the present inventor, the distance between the heating start position and the nip start position shown by D in the figure is D <5 m.
The occurrence of uneven density was suppressed when the thickness was about m. of course,
The photosensitive member 8 may contact the nip roller 44 before the heating roller 41.

By using a hard roller for the photosensitive member holding means in this way, it is possible to prevent density unevenness due to undulation of the photosensitive member at the heat development heating start position with a simple structure, and also to prevent fogging of the low density portion. Although it can be prevented, the temperature of the photosensitive member 8 does not rise completely while the photosensitive member 8 is in contact with the nip roller 44 for a short time. The temperature rise can be suppressed to a certain value. In this embodiment, the temperature is about 60 ° C. lower than the temperature of the heating roller 41. Therefore, the heat development is always kept started after passing through the nip roller 44, and the temperature of the nip roller 44 does not affect the heat development reaction.
A stable image can be obtained.

In all the above embodiments, the heating surface is the photosensitive member 8.
However, it was confirmed that the same effect can be obtained even if the heating surface is stationary and the photosensitive member is heated while sliding on the heating surface. There is. In that case, it is not always necessary to have a completely cylindrical shape, and a heat developing apparatus having a heating surface using a part of an arc may be used.

Further, in all of the above-described embodiments, the thermal developing apparatus is of a type in which the surface not coated with the photoconductor is mainly contacted and heated, but the surface coated with the photoconductor is mainly contacted. It may be a heating type thermal developing device.

Further, the present invention can be widely applied to all photothermographic materials, and is not limited to the photoconductive transfer type photothermographic material described in this embodiment.

In the present embodiment, the copying machine has been described as an example, but the present invention is not limited to this, and it is needless to say that the invention can be applied to all image forming apparatuses such as printers, facsimiles and electronic cameras. Absent.

[0028]

As described above, according to the present invention, a heat developing device for heating a heat-developable photosensitive member mainly by contacting from one surface thereof heats the photosensitive member near the heating start position. It has a photosensitive member sandwiching means for sandwiching between the parts, and preferably the photosensitive member sandwiching means is a hard roller, so that the heat development state of the photosensitive member can be accurately controlled, and the heating part due to thermal sizing in the heating part. It is possible to stably obtain a high-quality image having no density unevenness caused by the corrugation of the immediately preceding photosensitive member with a simple configuration.

[Brief description of drawings]

FIG. 1 is a front sectional view of an image forming apparatus using the present invention.

FIG. 2 is a perspective view of an embodiment of the heat developing apparatus of the present invention.

FIG. 3 is a sectional view of an embodiment of the heat developing apparatus of the present invention.

[Explanation of symbols]

 1 Original Plate 2 Original 3 Red Lamp 4 Green Lamp 5 Blue Lamp 6 Lens 7 Exposure Stand 8 Photosensitive Member 9, 13 Conveying Roller 10 Paper Tray 11 Transfer Member 12 Paper Feeding Device 14 Paper Ejection Tray 15 Manual Paper Feeding Port 16 Gas Filter 20 Cartridge 21 Winding Shaft 40 Thermal Development Device 41 Heating Roller 42 Bearing 43 Halogen Lamp Heater 44 Nip Roller 45 Spring 60 Pressure Transfer Device 61 Upper Roller 62 Middle Roller 63 Lower Roller 64 Separation Roller 65 Pinch Roller

Claims (2)

[Claims] 1. A heat development device for heating a heat-developable photosensitive member mainly by contacting from one side surface thereof, wherein the photosensitive member is substantially zero between the heating portions in the vicinity of a heating start position.
A photothermographic apparatus, characterized in that it has a photosensitive member sandwiching means for sandwiching the photosensitive member at a relative speed. 2. The heat developing apparatus according to claim 1, wherein the photosensitive member holding means is a hard roller.