JPH04143759A - Thermal fixing device - Google Patents

Abstract

PURPOSE:To prevent a thermal fixing belt from deforming even when left in a stationary state for a long time and to obtain sharp images by providing releasing means which release the thermal fixing belt from being tensed. CONSTITUTION:The thermal fixing belt 55 is tensed by tensing means 54 and 75 at all times. Then 1st detecting means 38, 80, and 81 detect fixing operation not being performed for a specific time and 2nd detecting means 80 and 85 detect electric power supply being cut from a power source to a heat generating means 52. At least one of them is outputted and releasing means 74 and 83 release the tensing operation of the tensing means 54 and 75 to release the thermal fixing belt 55 from being tensed. Consequently, the thermal fixing belt does not deform even when left in the stationary state for a long period and sharp images are obtained.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a heat-generating technology used in copying machines, etc., which heats and presses an image formed on a recording medium to fix the image on the recording medium. The present invention relates to a fixing device.

[Prior Art] Conventionally, in this type of heat fixing device, for example, a heat fixing belt is stretched between a heat roller and a tensioning roller, and pressure is applied to the heat roller via the heat fixing belt. The roller is pressed. Then, as the heat fixing belt rotates,
The recording medium is heated and pressurized while being sandwiched between a heat fixing belt and a pressure roller, and is conveyed, so that an image is fixed on the recording medium.

[Problems to be Solved by the Invention] However, in the belt-type heat fixing device described above, when the fixing operation is not performed, the heat fixing belt is stretched between the heat roller and the tension roller. It's still. Therefore, if the tensioning roller is left in the above state for a long time, a portion of the heat fixing belt along the outer periphery of the tensioning roller will be deformed if the tensioning roller has a small diameter. If the fixing operation is performed after the image has been left for a long time, there is a problem in that a mark of the deformed part remains on the image that comes into contact with the deformed part of the heat fixing belt, making it impossible to obtain a clear image.

The present invention has been made to solve the above-mentioned problems, and includes a release means for releasing the tensioned state of the heat fixing belt, so that the heat fixing belt does not deform even if left in a stationary state for a long time. An object of the present invention is to provide a heat fixing device that can produce clear images.

[Means for Solving the Problems] In order to achieve this object, the heat fixing device of the present invention includes a pair of rollers arranged a predetermined distance apart, and a roller stretched between the pair of rollers. The apparatus includes a heat fixing belt, a heat generating means disposed between a pair of rollers and generating heat by receiving power from a power supply, and a pressure roller that presses against the heat generating means with the heat fixing belt sandwiched therebetween. A tensioning means that is always maintained in a tensioned state, a first detection means that detects that the fixing operation has not been performed for a predetermined period of time, and a second detection means that detects that the power supply from the power source to the heat generating means is cut off. and a tensioning action of the tensioning means when at least one of the following: the first detection means detects that the fixing operation has not been performed for a predetermined period of time, or the second detection means detects that the power supply is cut off. and a release means for releasing the.

[Function] In the heat fixing device of the present invention having the above configuration, the heat fixing belt is always stretched by the tensioning means, but the first detection means detects that the fixing operation has not been performed for a predetermined period of time, or When the second detection means outputs at least one of the signals indicating that the power supply from the power supply to the heat generating means has been cut off, the release means releases the tensioning action of the tensioning means and releases the tensioned state of the heat fixing belt. do.

[Example] Hereinafter, an example embodying the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 shows a photosensitive and pressure sensitive copying machine 1 to which a heat fixing device according to the present invention is applied.

In the photosensitive and pressure sensitive copying machine 1, as shown in FIG.
8 (hereinafter referred to as recording paper) is used.

The surface of the support of the microcapsule paper 12 used in this example is coated with microcapsules, and the microcapsules contain dye precursors that react with the color developer described later. There is. A color developer is coated on the surface of the support of the color developer paper 28 and develops color by reacting with a dye precursor, but the details are described in US Pat. No. 4,399,209, etc., and will not be described here.

At the top of the copying machine, there is a document glass 2 and a document table cover 3.
A desired original 4 is placed on the original platen glass 2.
is placed face down and the document table cover 3 is closed.

A halogen lamp 5a and a reflector 5b are provided below the document table glass 2 in the upper part of the copying machine 1.

A light source unit 5 equipped with a reflecting mirror 8 and the like is disposed so as to be movable back and forth along a shaft 13 extending parallel to the document table glass 2. The light source section 5 irradiates light in a line toward the document table glass 2 in a direction perpendicular to the movement direction.

The irradiated light passes through the transparent document platen glass 2 and is reflected downward by the document 4 placed thereon.

Reflection mirrors 9a and 9b are disposed below the document table glass 2 and are movable separately from the light source section 5, and the light reflected from the document 4 is directed to the reflection mirrors 8.9a and 9b in this order. The light is reflected and guided in parallel to the moving direction of the light source section 5.

A normally fixed projection lens 7 and a filter 6 for adjusting the color tone of the copied image are disposed below the document platen glass 2, and the light reflected by the reflection mirror 6b passes through the projection lens 7. incident on .

The light projected by the lens 7 passes through a group of reflective mirrors 10
a and 10b.

An exposure stage 11 for exposing the microcapsule paper 12 is disposed to the right of the reflective mirror 10b, and a reflective mirror 10c for switching the optical path is disposed between the reflective mirror 10b and the exposure stage 11. ing. Image information on the original document 4 is formed on the microcapsule paper arranged along the exposure table 11.

Further, the reflecting mirrors 10a and 10b are normally fixed, but are set when enlarging or reducing the size of the latent image formed on the microcapsule paper 12, and change the optical path length according to a change in the projection magnification m. Therefore, they are configured to be able to move together in the axial direction of the shaft 13.

On the other hand, a cartridge 15 is disposed in the center of the copying machine 1, and a long microcapsule paper 12 is housed in the cartridge 15, which is removable from the machine while being wound around a cartridge shaft 14.

With the cartridge 15 set at a predetermined position within the machine, the leading end of the microcapsule paper 12 is pulled out toward the exposure table 11. A feed roller 19 and a dancer roller 21 for applying tension are arranged below the exposure table 11.

To the right of the dancer roller 21 is a large diameter roller 22a.
and a pressure developing device 22 including a backup roller 22b.
is arranged, and on the right side of the pressure developing device 22,
As will be described later, a separation roller 23 is provided to separate the microcapsule paper 12 and color developer paper 28 that are in close contact with each other.
A winding shaft 24 for fitting and holding the microcapsule paper 12 is disposed between the separation roller 23 and the cartridge 15.

Microcapsule paper 1 coming out from the top of cartridge 15
2 is guided by a tension roller 19 and passes above the exposure table 11, and then passes through a dancer roller 21 and a pressure developing device 2.
2 and further guided to a separation roller 23, and then wound onto a winding shaft 24. Note that the unexposed microcapsule paper 12 after leaving the cartridge 15 is maintained in an unexposed state by the light shielding cover.

A paper feed cassette 29 containing developer paper 28 is installed below the pressure developing device 22 . Above the paper feed cassette 29, a suction cup-type paper feed mechanism 30 that sucks paper using negative pressure suction is arranged, and the developer paper 28 is taken out one by one by the paper feed mechanism 30. . A feed guide 31d1 and feed rollers 31a, 31b, and 31c are disposed between the paper feed mechanism 30 and the pressure developing device 22, and the developer paper 2
8 is feed rollers 31a, 31b, 31c, feed guide 3
1d and carried into the pressure developing device 22.

A separation chute 27, which will be described later, is disposed on the right side of the pressure developing device 22, a heat fixing device 32 is disposed on the right side of the separation chute 27, and a heat fixing device 32 is disposed on the right side of the heat fixing device 32. A paper discharge tray 33 is provided for storing the color developing paper 28 on which an image has been formed.

A sensor 38 is disposed on the left side of the heat fixing device 32 to detect whether the color developing paper 28 has been conveyed to the heat fixing device 32. When the sensor 38 detects the color developing paper 28, it outputs a signal indicating this to a control section 80, which will be described later.

Next, the heat fixing device 32 will be explained with reference to FIG.

As shown in FIG. 2, the rake fixing device 32 has a pair of side plates 5
0 and a plurality of connecting plates 51 installed between both side plates 50. The heat roller 52 is rotatably supported between both side plates 50, and a heater 53 made of a halogen lamp or the like is provided inside the heat roller 52. The thermistor 64 is disposed close to the heat roller 52, and under the control of the thermistor 64, the surface temperature of the heat roller 52 is maintained at a predetermined temperature by the heating of the heater 53.

The tensioning roller 54 has shaft portions 70 at both ends fitted into an oblong hole 76 formed in the side plate 50, and is movable along the oblong hole 76 and rotatable around an axis parallel to the heat roller 52. is supported by

An endless heat fixing belt 55 is stretched between the heat roller 52 and the stretching roller 54. This heat fixing belt is connected to a belt driving motor 82.
When the heat roller 52 is rotated counterclockwise, it is rotated in the same direction and conveys the developing paper 28 toward the right in FIG. 2.

Further, an oval shaft 71 having an oval-shaped cross section is attached to both side plates 50.
The oval shaft 71 is rotatably supported in between, and levers 72 are provided at both ends of the oval shaft 71, respectively.

One end of this lever 72 supports the shaft portions 70 at both ends of the tensioning roller 54, and the other end of the lever 72 is connected to the other end of a spring 75 whose end is fixed to the side plate 50. It is being pulled towards the left in Figure 2. lever 72
The vicinity of the other end is in contact with a cam 74 that is rotatable around a shaft 73 by the tension of a spring 75 . This cam is connected to a cam drive motor 83, which will be described later.

A pair of rotating plates 56 are rotatably supported by the side plates 50 of the copying machine 10 via support pins 57.
A pressure roller 58 is rotatably supported between them. The pressure spring 59 is provided between the rotary plate 56 and the side plate 50 via support bolts 60, and the biasing force of the pressure spring 59 causes the pressure roller 58 or the heat roller 52 to be moved via the heat fixing belt 55. A predetermined nip pressure is applied to a part of the heat fixing belt 55 by pressing against the lower surface of the outer periphery of the heat fixing belt 55 .

The guide plate 61 is attached between both side plates 50 so as to extend along the conveyance path of the color developer paper 28 by the heat fixing belt 55.
On the right side thereof, a pair of paper discharge rollers 62 for discharging the color developer paper 28 to the paper discharge tray 33 is provided.

Furthermore, this copying machine has an autoloading function for automatically setting the microcapsule paper 12 on a predetermined transport path within the apparatus.

This is a function that automatically pulls out the leader film portion attached to the tip of the microcapsule paper 12 into the apparatus, transports it within the apparatus, and winds it around the winding shaft 24. As a result, the microcapsule paper 12 following the leader film section 18 is also wound up on the winding shaft 24, and the setting into the apparatus is completed.

For this automatic loading, a half-moon roller 17 is provided between the roller 19 and the cartridge 15 for pulling out the leader film section, and a take-up shaft 24 is provided between the roller 19 and the cartridge 15.
A separation chute 27 is rotatably mounted to guide the user. Around the winding shaft 24, a makitri guide unit 2 is provided to wind the leader film portion 18.
5 and a machining guide seat 26 are provided.

FIG. 3 shows a block diagram showing the electrical configuration of a control section that controls the heat fixing device 32. As shown in FIG.

The control unit 80 is composed of a microcomputer equipped with a CPU, ROM, RAM, etc. The control program shown in FIG. 4 is stored in the ROM, and the RAM has an internal flag. The thermistor 64, sensor 3B, and timer 81 are connected. The control unit 80 is connected to the heater 53, the belt drive motor 82, and the cam drive motor 83, and controls the heating of the heater 53 based on a signal from the thermistor 64, and also controls the heating of the heater 53 based on the signal from the thermistor 64.
The belt drive motor 82 or the cam drive motor 83 is driven and controlled based on the signal from 1.

The heater 53 and the motors 82 and 83 are connected to a power supply section 84 and receive power from the power supply section 84 . Note that the power supply section 84 is connected to a commercial power supply 86 via a switch 85. The switch 85 connects or cuts off power supply to the heater 53 and each motor 82, 83 by turning on/off. The switch 85 is connected to the control section 80 and its on/off operation is monitored by the control section 80 . The cam drive motor 83 is connected to a battery 85, and receives power from the battery 85 when the power supply from the power supply unit 85 is cut off.

Note that the switch 85 is also a switch for turning on power to the copying machine 1, and the power supply section 84 also supplies necessary power to other members of the copying machine 1.

Next, the operation of this copying machine will be explained.

When the cartridge 15 is set in the copying machine 1, autoloading is started.

The half-moon roller 17 rotates once to several times in the conveyance direction only when autoloading starts, and the leader film section 18
is fed to the rollers 20, then stopped, and subsequent conveyance is performed by driving the rollers 20.

Makitori guide sea urchin 25. When the auto-loading is completed, the machining guide shutter 26 and the separation chute 27 are rotated to the position shown by the - dotted chain line, and the leader film section 18 attached to the tip of the microcapsule paper 12 is wound around the winding shaft 24. The makitori guide urchin 25, the makitori guide sitter 26, and the separation chute 27 return to the positions indicated by solid lines, allowing copying.

When the copy start key is operated, the reflection mirror 8
The halogen lamp 5 has a moving speed of 1/m, where the transport speed of the microcapsule paper 12 is V and the projection magnification is m.
The reflecting mirrors 9a and 9b move at a speed of 1/
Moves at 2 mV.

The conveyance speed of the microcapsule paper 12 is determined by the mirror group 8.9a.
, 9b is synchronized as described above,
Latent images of predetermined lines of the document 4 are sequentially formed on the microcapsule paper 12 as it passes through the exposure stage 11 . Note that the predetermined speed ratio is predetermined based on the set value of the magnification.

The microcapsule paper 12 on which the latent image has been formed is transported,
The topmost color developing paper 28 of the paper feed cassette 29 is fed to the paper feed mechanism 30.
．． It is conveyed by feed rollers 31a, 31b, 31C, etc.

The pressure developing device 22 is supplied with the microcapsule paper 12 and the color developer paper 28 in close contact with each other, and the microcapsule surface on which the latent image of the microcapsule paper 12 is formed and the color developer of the color developer paper 28. The coated surface is integrally sandwiched between the large diameter roller 22a and the backup roller 22b in a state in which they are in contact with each other on the inside, and pressure is applied. This pressure destroys the unexposed microcapsules and forms an image on the developer paper 28.

The microcapsule paper 12 and color developer paper 28 that come out of the pressure developing device 22 are separated by a separation roller 23, and then the color developer paper 28 is conveyed into the heat fixing device 32, and the separated microcapsule paper 12 is separated. Winding shaft 2 via roller 23
It is wound up in 4.

Next, the operation of the heat fixing device 32 will be explained with reference to the flowchart shown in FIG. In addition, the following Si (
i-1, 2, 3...) indicates each step.

When the copying machine 1 is powered on by turning on the switch 85, the control unit 80 resets the internal flag F and drives the cam drive motor 83 to rotate the cam 74 clockwise in FIG. , the cam 74 is held in the position shown by the solid line in the figure. As the cam 74 moves, the lever 72 is pulled by the spring 75 and rotates counterclockwise in FIG. Move to the position shown by the solid line on the right. This movement puts the heat fixing belt 55 in a tensioned state. The control unit 80 also drives a belt drive motor 82 to rotate the heat roller 52.

Along with this rotation, the heat fixing belt 55 rotates. At the same time, the control unit 80 energizes the heater 53 to heat the heat roller 52 . Then, the control program shown in FIG. 4 is executed.

First, the control unit 80 determines whether or not the sensor 38 outputs a signal indicating that the color developing paper 28 has been detected (Sl). At this time, when the color developing paper 28 with an image formed on its surface is conveyed into the heat fixing device 32, a signal is output from the sensor 38 (Sl: YES), so the control unit 80 controls the internal flag F to be "1". ” (Sll). If the power is turned on immediately, the internal flag F is "0" (611: No
), the control unit 80 executes Sl again. If the developing paper 28 is continuously conveyed, S1 and Sll are repeated.

If the next developing paper 28 is not conveyed, the sensor 38 will not output a signal (Sl/No), so the control unit 8
0 resets the timer 81 and causes the timer 81 to start measuring time (S2). Then, S3. Repeat S9 (S3: NO, S9: NO). During this time, the conveyed developer paper 28 is not pressed between the pressure roller 58 and the heat fixing belt 55, but is heated by the heat generated by the heater 53 via the heat roller 52 and the heat fixing belt 55.
The color developer on the color developer paper 28 is melted. Therefore, the color developer paper 2B is stuck to the lower running portion of the heat fixing belt 55 and is conveyed as the heat fixing belt 55 rotates. During this time, the image is fixed on the developer paper 28. This color developing paper 28 is then cooled by a cooling fan (not shown). This cooling solidifies the developer on the developer paper 28, so the developer paper 28 is peeled off from the heat fixing belt 55 at the tension roller 54.
The paper is ejected onto the paper ejection tray 33 by the paper ejection roller pair 62 .

The timer 81 finishes counting the predetermined time (S3
: YES), the control unit determines that the thermal fixing device 32 has not performed a fixing operation for a predetermined period of time or more, and stops driving the belt drive motor 82 to stop the heat roller 52 and the thermal fixing belt 55 (S4). ), cam drive motor 8
3 to rotate the cam 74 counterclockwise in FIG. 2 and move it to the position shown by the broken line in the same figure (S5). As the cam 74 moves, the lever 72 rotates clockwise in the figure and moves from the position shown by the solid line to the position shown by the broken line. Along with this movement, the tensioning roller 54 moves to the left to the position shown by the broken line. By this movement of the tensioning roller 54, the tensioned state of the heat fixing belt 55 is released. and,
In order to lower the temperature of the heat roller 53, the control unit 80
The heater 53 is controlled (S6), the timing of the timer 81 is stopped and the timing is reset (S7), and the internal flag F is reset (S8). Then, it waits for the signal from the sensor 3B to be output (S9: NO).

Before the timer 81 finishes counting the predetermined time, the developer paper 28 is conveyed to the heat fixing device 32 and the sensor 38
When a signal is output from (S10: YES), the control unit 8
0 causes the timer 81 to stop counting and reset the timing (5ll), and returns to S12. At this time, since the internal flag F is "0", S1 to S3. S1
0 is executed.

During the standby in S9, the developer paper 28 or the heat fixing device 3
2 and a signal is output from the sensor 38 (S
9: YES), the above S12 is executed. At this time, since the internal flag F was set in S8 and is "1" (S12 YES), the control unit 80 causes the heater 53 to generate heat in order to raise the temperature of the heat roller 52 (S13), and the cam drive motor 83 to rotate the cam 74 clockwise in FIG. 2 to move it from the position shown by the broken line to the position shown by the solid line (S14). Along with this movement, the lever 72 is pulled by the spring 75 and rotates counterclockwise in FIG. Move to the position shown by the solid line. This movement causes the heat fixing belt 55 to become stretched again.

Then, the control unit 80 drives the belt drive motor 82 to rotate the heat roller 52 (S15), and performs a fixing operation on the developer paper 28 that has been conveyed. Also, the internal flag F is reset.

As described above, in the copying machine 1, when the thermal fixing device 32 does not perform a fixing operation for a predetermined period of time or more while the power is turned on, the tensioned state of the thermal fixing belt 55 is released.

On the other hand, when the power is turned off by the OFF operation of the switch 85, the control section 80 detects the OFF operation of the switch 85, and when the internal flag F is "0", that is, the heat fixing belt 55 is in the tensioned state. At this time, the cam drive motor 83 is driven to rotate the cam 74 to the position shown by the broken line in FIG. As a result, the lever 72 rotates, the tensioning roller 54 moves to the right in FIG. 2, and the tensioned state of the heat fixing belt 55 is released. At this time, power is supplied to the cam drive motor 83 from the battery 87.

In the above embodiment, the heat roller 52 and the tensioning roller 54 constitute a pair of rollers, and the heat roller 52 constitutes a heat generating means. Further, the tensioning row 54, the lever, and the spring 75 constitute a tensioning means, and the cam 74 and the cam drive motor 83 constitute a release means. Furthermore, a sensor 38, a timer 81, a control unit 8
83 processing of 0 constitutes the first detection means, and the control unit 80
and switch 85 constitute a second detection means.

As described in detail above, in the copying machine 1 of the present embodiment, the tensioned state of the heat fixing heald 55 is released when the heat fixing device 32 does not perform a fixing operation for a predetermined period of time or more while the power is turned on. Furthermore, even when the power is turned off, the tensioned state of the heat fixing belt 55 is released, so that the heat fixing belt 55
The image is not deformed and a clear image can be obtained.

Further, the heat roller 52 serves both as a roller for tensioning the heat fixing belt 55 and as a tensioning means, and the tensioning roller 54 serves as a roller for tensioning the heat fixing belt 55 and as a part of the tensioning means. Therefore, the structure of the heat fixing device 32 can be simplified and the size can be reduced.

Further, in the above embodiment, when the tension of the heat fixing belt 55 is released, its rotation also stops, but at this time, control is performed to lower the temperature of the heat roller 52, so that the heat roller 52 of the heat fixing belt 55 This prevents the portion sandwiched between the pressure roller 58 and the heat roller 52 from being deformed by the heat of the heat roller 52.

The present invention is not limited to the one embodiment described above, and various modifications can be made without departing from the spirit thereof.

The heat fixing device of the present invention can also be applied to laser printers and the like other than copying machines.

[Effects of the Invention] As is clear from the detailed description above, the present invention provides a heat fixing device in which the heat fixing belt does not deform even if left in a stationary state for a long time and a clear image can be obtained. can do.

[Brief explanation of the drawing]

1 to 4 show an embodiment embodying the present invention, FIG. 1 is a sectional view showing a schematic configuration of a photosensitive pressure copying machine to which the heat fixing device of the present invention is applied, and FIG. FIG. 3 is a sectional view showing the structure of the heat fixing device, FIG. 3 is a block diagram showing the electrical structure of a control section for controlling the heat fixing device, and FIG. 4 is a flow yard showing the control program. In the figure, 38 is a sensor, 52 is a heat roller, 54 is a tensioning roller, 55 is a heat fixing belt, 72 is a lever, 74 is a cam, 75 is a spring, 80 is a control unit, 81 is a timer, 8
3 is a cam drive motor, 85 is a switch, and 86 is a commercial power source.

Claims (1)

[Claims] 1. A pair of rollers disposed a predetermined distance apart, a heat fixing belt stretched between the pair of rollers, and a heat fixing belt disposed between the pair of rollers that receives power from a power source. It includes a heat generating means that generates heat upon receiving supply, and a pressure roller that presses against the heat generating means with the heat fixing belt sandwiched therebetween. In a thermal fixing device that applies pressure and heat to fix an image on a recording medium and conveys the recording medium by rotation of a thermal fixing belt, a tensioning means that always maintains the thermal fixing belt in a tensioned state; a first detection means for detecting that the fixing operation has not been performed for a predetermined time; a second detection means for detecting that power supply from the power source to the heat generating means has been cut off; and a release means for releasing the tensioning action of the tensioning means when at least one of the fact that the operation is not performed for a predetermined period of time or the second detection means detects that the power supply is cut off. A heat fixing device characterized by: