JPH05165184A - Image forming device - Google Patents

Abstract

PURPOSE:To stabilize the density of an image by precisely controlling the heat developing temperature of a photosensitive member, to eliminate the waviness of the photosensitive member occurring just before the heating part of a heat developing device and to prevent the quality of the image from being deteriorated by the irregularity of the density caused by it. CONSTITUTION:The heat developing device is provided with a heating roller 41 and a nip roller 44 which can select an opening state and an pinching state. Then, the photosensitive member 8 is pinched by the rollers 41 and 44 near a heating start position by the roller 41 only at a developing action time. Besides, the opening state is attained when and abnormality occurs to an image forming action.

Description

Detailed Description of the Invention

[0001]

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

[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 during that time. This endless belt was constantly orbiting the circumferential surface of the heating roller.

Further, in the conventional example of the heat developing apparatus disclosed in Japanese Patent Application No. Hei 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 contacted and 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 low as the time elapses after the power is turned on even though the heating roller is controlled at a constant temperature. Was seen. This is because the endless belt is always in contact with the heating roller, and therefore the heat 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 has been made in view of the above circumstances and solves the above problems. An object of the present invention is to stably obtain a high quality image by heating a photosensitive member in a stable and uniform manner. It is to provide a heat developing device of a forming apparatus simply and at low cost.

[0011]

An image forming apparatus of the present invention has a heat developing device for heating a photosensitive member using a heat developing photosensitive member, and the heat developing device is provided near a heating start position. It is characterized in that it has a photosensitive member sandwiching means for sandwiching the photosensitive member between the heating sections in a time-selective manner. Furthermore, (1) the photosensitive member sandwiching means comprises the photosensitive member during non-developing operation of the photosensitive member. Do not clamp
(2) The image forming apparatus includes at least one detecting device that detects an operation of a predetermined image forming step, and the photosensitive member holding means causes the photosensitive member sandwiching means to detect the operation when the detecting device detects an abnormal operation of the image forming step. It is desirable not to clamp the members.

[0012]

EXAMPLES The image forming apparatus of the present invention will be described in detail below with reference to examples.

FIG. 1 is a front sectional view of a copying machine which is an embodiment of the image forming apparatus 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 heat-developed by the heat developing device 40 having the nip roller 44, which is the photosensitive member teaching 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, the heat developing apparatus of one embodiment of the image forming apparatus of the present invention will be described in detail. FIG. 2 is a perspective view showing the heat developing device 40 of the image forming apparatus of FIG. The photosensitive member 8 is sandwiched between the nip roller 44 and the heating roller 41 so that the side on which the microcapsule is applied contacts the nip roller 44 at the heating start position of the heating roller 41. The nip roller 44 can be separated from the heating roller 41. In the area other than the heating start position, a predetermined amount is wound around each of the heating rollers 41 having a heating peripheral surface so that the side not coated with the microcapsules comes into contact with each other, and the contact rollers are heated while being fed under tension. It Both ends of the heating roller 41 are rotatably supported by bearings 42. In addition, the heating roller 41
Has a halogen lamp heater 43 inside the cylinder,
The heating amount is appropriately controlled so that the heating peripheral surface is kept at a predetermined temperature between about 120 ° C and 160 ° C. The nip roller 44 is attached to a lever 46 which is swingable about a rotary shaft 49 attached to a frame (not shown),
It is rotatably attached. Lever 46 is spring 45
Is urged toward the heating roller 41. Spring 45
Has one end fixed to a frame (not shown) and the other end fixed to a lever 46. A cam 48, which is rotationally driven by a motor (not shown), causes the lever 46 to spring 45 depending on the rotational position.
Lift in the direction opposite to that in which the force is applied.

Next, the operation of the nip roller 44 will be described with reference to the sectional view of FIG. FIG. 3 a shows a nip roller 44
And the heating roller 41 sandwiches the photosensitive member 8 (sandwiched state). The cam 48 is in a position where it does not contact the lever 46, and the pressing force of the nip roller 44 is generated by the spring 45. FIG. 3B shows a case where the nip roller 44 and the heating cylinder 41 do not sandwich the photosensitive member 8 (open state). The cam 48 overcomes the biasing force of the spring 45 and pushes up the lever 46, and the nip roller 44 causes the photosensitive member 8 to move.
Is not in contact with.

Next, the arrangement position of the nip roller will be described. FIG. 4 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.

In the present embodiment, when the copying operation is started, the image of the original document starts to be formed on the photosensitive member 8 as a latent image. The cam 48 is rotated to a predetermined position immediately before it hits the heating roller 41, so that the cam 48 is held. When the copying operation is performed for only one image, the photosensitive member 8 is continuously conveyed until the end of the image area passes through the pressure transfer device 60, so that the sandwiched state is maintained during that period.
After that, it shifts to the open state. When the copying operation is continuously performed, the holding state is maintained until the image area of the final image has finished passing through the pressure transfer device 60.

By using the photosensitive member sandwiching means as described above, it is possible to prevent the uneven density due to the corrugation of the photosensitive member 8 at the heat development heating start position with a simple structure. While the photosensitive member 8 is in contact with the nip roller 44 for a short period of time during this period, the temperature of the photosensitive member 8 cannot be completely raised during the contact, and the photosensitive member 8 is stationary. Since the nip roller 44 is in the open state while the nip roller 44 is open, there is no heat conduction from the heating roller 41, and therefore the temperature rise of the nip roller 44 itself is suppressed to a certain value. In this embodiment, the temperature is lower than the temperature of the heating roller 41 by about 80 ° C. Therefore, the heat development reaction is always kept started after passing through the nip roller 44, and a stable image can be obtained.

Next, the operation of the nip roller 44 when an abnormality occurs in the image forming process will be described. FIG. 5 is a block diagram of an image forming operation abnormality detection system of the image forming apparatus of this embodiment. The sensors for detecting an abnormality include photosensitive member conveyance detection, transfer member conveyance detection, document table operation abnormality detection, thermal development temperature abnormality detection, pressure transfer temperature abnormality detection, and pressurization abnormality detection. Each detecting operation and the operation of the nip roller 44 will be described. The photosensitive member conveyance detection detects whether or not the photosensitive member is correctly conveyed, and the rotation speed of the rotation shaft of the cartridge 20 is detected by an encoder of a type in which the rotation of the rotary slit disk is detected by a photoelectric sensor. That is, when the slit window part on the disk comes over the photoelectric sensor, the light from the light emitting element reaches the light receiving element, and when the part other than the slit window comes over the photoelectric sensor, the light from the light emitting element blocks the disk. It does not reach the light receiving element. Therefore, when the rotary slit disk rotates, an ON / OFF signal is continuously output from the light receiving element, and the conveyance speed of the photosensitive member 8 is detected by the frequency. If the detected transport speed of the photosensitive member 8 exceeds a predetermined range, a normal image cannot be obtained regardless of whether the photosensitive member 8 is jammed in the main body of the apparatus or is not synchronized. Therefore, the nip roller 44 is opened.

In the transfer member conveyance detection, the lever disposed in the transfer member conveyance path is tilted when the transfer member 11 passes therethrough, and the light of the photoelectric sensor arranged at one end of the lever is blocked so that the transfer member 11 is conveyed in the path. The presence or absence of is detected. It is detected whether the transfer member 11 has reached or has already passed the transfer member conveyance detection position at a predetermined time during the copying operation, and if it is different from the expected signal, it is considered that a paper jam has occurred and the nip roller 44 is opened.

In the detection of the original table abnormality, the original table 1 is tilted when the original table 1 passes a lever arranged in the path along which the original table 1 moves, and the presence or absence of the original table 1 is detected as in the transfer member conveyance detection. It detects whether the platen glass 1 has reached or has already passed the position of the platen glass abnormality detection at a predetermined time during the copying operation, and if the signal is different from the expected signal, the platen glass is not correctly moved. Assuming that a normal image cannot be obtained, the nip roller 44 is opened.

With respect to the abnormal heat development temperature detection and the abnormal pressure transfer temperature detection, a normal image can be obtained if the temperature detected by the thermistor slidably attached to the heating roller 41 and the upper roller 61 exceeds a predetermined range. If not, the nip roller 44 is opened.

In the pressurization abnormality detection, the position of the middle roller 62 of the pressure transfer device capable of selecting pressurization or release is detected by a detector similar to that of the document table abnormality detection, and the pressurization state or the open state is detected. To detect. The nip roller 44 is opened when the transfer member 11 is pressing at a timing not present in the pressure transfer portion, or when the transfer member 11 is not pressing at a timing present in the pressure transfer portion.

By performing the above-mentioned abnormal processing operation, it is possible to prevent the nip roller 44 from being left in the sandwiched state while the photosensitive member 8 is stopped, and the nip roller 44 is kept.
Can be prevented from affecting the state of heat development during the next copying operation, the nip roller 44 becoming dirty, or sticking to the photosensitive member 8 in a significant case. Further, when the photosensitive member 8 is jammed, it can be easily released.

In all of 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.

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 present invention can be applied to all image forming apparatuses such as printers, facsimiles, electronic cameras and the like. Absent.

[0032]

As described above, according to the present invention, an image forming apparatus using a heat-developable photosensitive member and having a heat developing device for heating the photosensitive member is used, and the heat developing device starts heating. In the vicinity of the position, there is provided photosensitive member sandwiching means for sandwiching the photosensitive member between the heating parts in a time selective manner, and more preferably, (1) the photosensitive member sandwiching means is configured to expose the photosensitive member when the photosensitive member is not developing. Do not clamp members,
(2) The image forming apparatus includes at least one detecting device that detects an operation of a predetermined image forming step, and the photosensitive member holding means causes the photosensitive member sandwiching means to detect the operation when the detecting device detects an abnormal operation of the image forming step. Since the member is not clamped, the heat development state of the photosensitive member can be accurately controlled, and high quality without uneven density generated by the corrugation of the photosensitive member immediately before the heating unit due to thermal sizing in the heating unit. This has an effect that an image can be stably obtained with a simple structure. Further, there is an effect that it is possible to provide a highly reliable image forming apparatus without damaging the state of the apparatus even when an abnormality occurs in the image forming operation.

[Brief description of drawings]

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

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

FIG. 3 is a sectional view showing the operation of the heat developing apparatus of the embodiment of the image forming apparatus of the invention.

FIG. 4 is a cross-sectional view of a heat developing device of an embodiment of the image forming apparatus of the present invention.

FIG. 5 is a block diagram showing an abnormality detection system of an embodiment of the image forming 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 Heat Developing Device 41 Heating Roller 42 Bearing 43 Halogen Lamp Heater 44 Nip Roller 45 Spring 46 Lever 48 Cam 49 Rotating Shaft 60 Pressure Transfer Device 61 Upper Roller 62 Middle Roller 63 Lower Roller 64 Separation Roller 65 Pinch Roller

Claims (3)

[Claims] 1. An image forming apparatus using a heat-developable photosensitive member has a heat developing device for heating the photosensitive member, and the heat developing device selects a time between the heating units in the vicinity of a heating start position. An image forming apparatus characterized by further comprising a photosensitive member holding means for holding the photosensitive member. 2. The image forming apparatus according to claim 1, wherein the photosensitive member sandwiching means does not sandwich the photosensitive member during a non-developing operation of the photosensitive member. 3. The image forming apparatus includes at least one detecting device for detecting an operation of a predetermined image forming process, and the photosensitive member holding means is provided when the detecting device detects an abnormal operation of the image forming process. The image forming apparatus according to claim 1, wherein the photosensitive member is not sandwiched.