JPH0530854U - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to prevent the belt of a heat fixing device from meandering and to always obtain a good image. When the belt meandering is detected when there is no sheet in the heat fixing device, the tension varying means is driven to correct the belt meandering. Further, when the belt meandering is detected during the continuous copying operation, the sheet spacing is opened while waiting for the next copying operation, and the tension varying means is driven in the meantime to correct the meandering.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having a belt-type heat fixing device provided with a meandering correction means.

[0002]

[Prior Art]

 Conventionally, a belt-type heat fixing device has been used in an image forming apparatus using light and pressure sensitive microcapsules. In recent years, in PPC copiers, the conventional method of heating with a halogen lamp that incorporates a heat roller made of a hollow aluminum tube requires a long time to start up after the power is turned on. A heating means in which a heating element is brought into contact with the belt is used.

The structure of a conventional belt-type heat fixing device used in an image forming apparatus using light- and pressure-sensitive microcapsules will be described with reference to FIGS. 4 and 5. The heat roller 17 is made of a hollow aluminum pipe and is rotatably supported. A halogen lamp 19 is fixed to the center of the heat roller 17. A nip roller 18 is rotatably supported at a position facing the heat roller 17 via a belt 20. A belt 20 is wound around the heat roller 17 and the pulling roller 21. The pulling roller 21 gives a predetermined tension to the belt 20 by the spring member 30. The surface temperature of the heat roller is measured by a temperature sensor 45 and controlled to a constant temperature by a temperature control circuit (not shown).

On the other hand, inside the belt 20, guide shafts 31 for changing the tensions at the left and right ends of the belt are provided. One end of the guide shaft 31 is supported by the arm member 32, and the other end is supported by a bearing (not shown) so that the angle can be freely changed. The arm member 32 is rotatably supported by the support shaft 33. Further, the rear end portion of the arm member 32 is in contact with the projection 35 provided on the cam member 34. The arm member 32 is urged against the protrusion 35 by the belt tension.

Detection sensors 36 and 39 for detecting the meandering of the belt 20 are provided on both end surfaces of the belt, and the belt 20 meanders in the Y direction in the drawing to detect the end portion of the belt 20. When detected by 39, the cam 34 is rotated about the central axis 37 in the direction of arrow A in FIG. Thereby, the guide shaft 31 rotates in the direction A1, the front tension of the belt 20 is released from the tension on the back side, and the meandering of the belt is corrected in the arrow X direction. Further, when the belt 20 meanders in the X direction in the drawing and the detection sensor 36 detects the end portion of the belt 20, the step motor 38 rotates the cam member 34 in the arrow B direction in FIG. As a result, the guide shaft 31 rotates in the direction B1, the back side tension of the belt 20 is loosened from the front side tension, and the belt is meandered and corrected in the arrow Y direction.

An apparatus having such a meandering correction mechanism has already been used as a heat fixing apparatus of an image forming apparatus using a light and pressure sensitive microcapsule. In the heat fixing device, heat is applied to the transfer paper 6 on which the predetermined image processing has been performed. The transfer paper 6 is conveyed to the heat fixing device by the feed roller, heated by passing between the belt 20 and the nip roller 18, and the developer surface comes into close contact with the belt and adheres to the belt surface. At this time, the binder polymer (binder resin) applied to the transfer paper is melted by heat to make the surface of the transfer paper 6 smooth and glossy. The heat-treated transfer paper 6 is conveyed by the belt 20 and is separated in curvature by the pulling roller 21, and the heat fixing is completed.

[0007]

[Problems to be solved by the device]

 However, in the above device, when the detection sensors 36 and 39 detect the meandering of the belt 20, the cam member 34 is immediately rotated and the guide shaft 31 is operated, so that the balance of the belt tension is temporarily reduced. Sometimes it collapsed. In that case, the belt 20 must continue to rotate for a while until the tension of the belt 20 is balanced again. At this time, since the tension of the belt 20 cannot be balanced, the belt 20 is greatly twisted and wavy, and wrinkles are generated on the belt surface. When the transfer paper is conveyed to the apparatus while the belt 20 is wrinkled, the heat-melted binder polymer of the transfer paper 6 is displaced from the belt 20 by the wrinkles, so that the formed image is distorted or the image is deformed. There is a problem that the glossiness of the surface is roughened, which hinders image formation.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide an image forming apparatus capable of obtaining a good image while correcting the meandering of the belt.

[0009]

[Means for Solving the Problems]

 In order to achieve this object, an image forming apparatus of the present invention comprises a plurality of rollers, a belt mounted on the plurality of rollers, and a nip roller facing the rollers and pressed against the surface. It has a thermal fixing device that heats the sheet with the image formed on it while it is being conveyed by a belt.The meandering detection means for detecting the meandering of the belt and the meandering by changing the tension on the left and right ends of the belt Tension changing means to be corrected, driving means for driving the tension changing means in response to the signal from the meandering detection means, and control for prohibiting the driving of the tension changing means when there is a sheet in the thermal fixing device. And means.

Further, in the image forming apparatus of the present invention, in the above-mentioned one, when the meandering detecting means detects the meandering during the continuous image forming operation, the next image forming operation is started. It is preferable to have a control unit that delays the sheet interval to allow the sheets to come into the heat fixing device and to control the tension varying unit during the sheet interval.

[0011]

[Action]

 The control means of the image forming apparatus of the present invention having the above structure stores at which position in the apparatus the sheet exists. When the belt meandering is detected when there is no sheet in the thermal fixing device, the tension varying means is driven to correct the belt meandering. If belt meandering is detected when a sheet is present in the thermal fixing device, it is prohibited to drive the tension varying means to correct the belt meandering. When belt meandering is detected during continuous copying operation, the sheet spacing is kept waiting for the next copying operation and meanwhile the tension varying means is driven to correct the meandering.

[0012]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the overall construction of a copying machine which realizes the image forming apparatus of the present invention. The copying machine 1 is composed of an optical device 2 and an image recording device 3. First, the configuration of the optical device 2 will be described. The light- and pressure-sensitive microcapsule paper 8 (hereinafter referred to as microcapsule paper 8) is supplied to the copying machine 1 in a state of being housed in a light-shielding cartridge 7. The cartridge 7 is composed of a supply shaft 7a around which an unused microcapsule paper 8 is wound, and a take-up shaft 7b around which the microcapsule paper 8 that has finished transferring an image onto the transfer paper 6 is wound up. There is. The microcapsule paper 8 is, for example, a microcapsule made of a photocurable resin containing a dye precursor applied to a PET base. Here, the photocurable resins are three types of resins that are selectively cured depending on the wavelength of light. Therefore, when the color image is exposed, the photocurable resin corresponding to the color image is cured and a latent image is formed.

A document table glass 10 is arranged on the upper part of the copying machine 1, and a desired document is placed on the document table glass 10. A light source unit including a halogen lamp 11, five reflection mirrors 12, a lens 9, a filter 16 and the like is disposed below the original table glass 10 in the upper part of the copying machine 1. The light source unit irradiates the original glass plate 10 with light on a line in a direction orthogonal to the moving direction. Further, the light source unit moves in parallel with the original document to scan the entire original document. An exposure table 15 for exposing the microcapsule paper 8 is arranged to the right of the reflection mirror 12e. Image information on the original is imaged on the microcapsule paper 8 arranged along the exposure table 15.

On the other hand, in the center of the copying machine 1, a cartridge 7 containing a microcapsule paper 8 is attached. With the cartridge 7 set at a predetermined position inside the machine body, the tip of the microcapsule paper 8 is pulled out toward the exposure table 15. A pressure developing device 5 including a pressing roller 5a, a small-diameter roller 5b, and a backup roller 5c is disposed under the exposure table 15, and a used microcapsule paper 8 is placed on the upper right of the pressure developing device 5. A winding shaft 7a for winding is arranged. The microcapsule paper 8 coming out of the upper part of the cartridge 7 passes over the exposure table 15, passes through the pressure developing device 5, and is wound around the winding shaft 7a. The unexposed microcapsule paper 8 after exiting the cartridge 7 is kept in an unexposed state by a light-shielding cover.

Below the pressure developing device 5, a paper feed cassette 6 a containing the transfer paper 6 is mounted. The transfer paper 6 is coated with a developer that chemically reacts with a dye precursor to form a dye. The transfer paper 6 is in the form of a cut sheet and is supplied to the copying machine 1 in a state of being contained in the paper feed cassette 6a. Above the paper feed cassette 6a, a suction cup-type paper feed mechanism 14 that attracts paper by using negative pressure suction is disposed, and the transfer papers 6 are taken out one by one by the paper feed mechanism 14. The microcapsule paper 8 and the transfer paper 6 are superposed and supplied to the pressure developing device 5 so that the microcapsule surface of the microcapsule paper 8 and the developer surface of the transfer paper 6 are in contact with each other. The microcapsule paper 8 is pressed by the pressure developing device 5, the non-photocured microcapsules are destroyed, the dye precursor exudes and moves to the transfer paper 6, and is mixed with the color developer.

A thermal fixing device 4 is arranged on the right side of the pressure developing device 5, and a discharge tray 13 for accommodating the transfer sheet 6 on which an image is formed is arranged on the right side of the thermal fixing device 4. Has been done. The transfer paper 6 on which the image is formed by the pressure developing device 5 is heated by the heat fixing device 4 to accelerate the chemical reaction between the dye precursor and the color developing material, and a protective layer is formed on the surface of the transfer paper 6. A color image of the original is copied on top. The transfer paper 6 on which the color image is formed is discharged from the copying machine 1 onto the paper discharge tray 13.

Next, the operation of the copying machine will be described. When the copy start key is operated, the light source scans the original and forms a latent image on the microcapsule paper 8 on the exposure table 15. The operation of the optical system is the same as that of a normal PPC copying machine, and the explanation is omitted here. The microcapsule paper 8 on which the latent image is formed is conveyed, and the uppermost transfer paper 6 in the paper feed cassette 6a is conveyed by the paper feed mechanism 14 or the like.

The pressure developing device 5 is supplied in a state where the microcapsule paper 8 and the transfer paper 6 are in close contact with each other and integrated, and the microcapsule surface on which the latent image of the microcapsule paper 8 is formed and the transfer paper 6 are provided. Pressure is applied to the developer application surface by being sandwiched by the large-diameter roller 5a and the small-diameter roller 5b in a state where they are in contact with each other on the inside. This pressure destroys the unexposed microcapsules, and an image is formed on the transfer paper 6. The microcapsule paper 8 and the transfer paper 6 which have come out of the pressure developing device 5 are separated by the separation roller 5 d, and then the transfer paper 6 is accelerated by the heat roller 17 of the heat fixing device 4 to form an image. After being ejected, the paper is ejected to the paper ejection tray 13 by the paper ejection roller 23. The separated microcapsule paper 8 is taken up by the take-up shaft 7b via the separating roller 5b.

The structure of the mechanical parts of the heat fixing device, which is the main part of the present invention, is almost the same as that shown in FIGS. 4 and 5 which have been described as the prior art, but the heat fixing device 4 has an inlet and an outlet. The difference is that paper sensors 46 and 47 shown by dotted lines in the figure for detecting the transfer paper 6 are additionally provided. Next, the control device of the heat fixing device will be described with reference to FIG. The main body of the control device is a microcomputer 42 including a CPU 44, a RAM 40, and a ROM 41. In addition to this, a step motor 38 is connected via a step motor drive circuit 43, and detection sensors 36 and 39 that detect the meandering of the belt and paper sensors 46 and 47 that detect the presence or absence of a sheet in the heat fixing device. Are connected to each other.

Next, the control operation of the thermal fixing device 4 will be described with reference to the flowchart of FIG. In the heat fixing device 4, the heat roller 17 is rotated by a drive source (not shown), and the belt 20 is rotated in the transfer paper conveying direction accordingly. The heat roller 17 is heated by a halogen lamp 19 fixed inside, the temperature is measured by a temperature sensor 45, and is controlled to a predetermined temperature by a temperature control circuit (not shown). The transferred transfer paper 6 is sandwiched between the belt 20 and the nip roller 18 with the color-developed surface on which the image is formed facing up. The image surface is heated by the heat roller 17, adheres to the belt, and the transfer paper 6 adheres to the belt surface. At this time, the binder polymer (binder resin) applied on the surface of the transfer paper 6 is melted by heat to make the surface of the paper surface smooth and glossy. The transfer paper 6 is conveyed by the belt 20 and separated by the pulling roller 21 while the color developing surface remains adhered, and the heat fixing operation is completed.

Due to the mounting accuracy of the heat roller 17 and the pulling roller 21, the belt 20 often meanders to the left or right as it rotates. By the meandering of the belt 20, the detection sensor 36 or the detection sensor 39 detects the end surface of the belt (S 1). At this time, the control device 42 that controls the copying machine 1 detects the presence or absence of the sheet in the heat fixing device by the paper sensors 46 and 47, and the detection result indicates that the transfer paper is in the heat fixing device. If it is determined that there is not (S2), if the detection sensor 36 is ON (S3), the step motor 38 rotates in the direction of arrow B in FIG. 5 (S4). Thereby, the cam 34 rotates in the same direction, and the arm member 32 rotates in the arrow B1 direction. Then, the guide shaft 31 is lowered to the back side, the belt tension on the back side is weakened against the front side, and the belt 20 is gradually meandered in the direction of the arrow Y.

When the meandering is corrected, both the detection sensors 36 and 39 are turned off (S7), and the step motor 38 returns to the neutral position (S8). This is because if the guide shaft 31 is continuously maintained in this state, the meandering in the opposite direction will occur.

On the contrary, when the detection sensor 39 is detected to be ON (S5), the step motor 38 rotates in the direction of arrow A in FIG. 4 (S6). As a result, the cam 34 rotates in the same direction, and the arm member 32 rotates in the arrow A1 direction. Then, the guide shaft 31 rises on the back side, the belt tension on the back side is strengthened with respect to that on the front side, and the belt 20 is gradually meandered in the direction of the arrow X. When the meandering is corrected, both the detection sensors 36 and 39 are turned off (S7), and the step motor 38 returns to the neutral position (S8).

According to this control, even if the belt 20 of the thermal fixing device 4 meanders during the copying operation, if the transfer paper 6 is in the thermal fixing device, the meandering correction is prohibited. A beautiful image can be formed without generating creases. Further, the meandering correction of the belt 20 is promptly performed when the transfer paper 6 runs out in the thermal fixing device 4.

On the other hand, when the detection sensors 36 and 39 detect the meandering of the belt during the continuous copying operation, the transfer paper is ejected from the heat fixing device without starting the next copying operation. wait. After the transfer paper is ejected, the meandering correction operation is performed, and the next copy operation after the correction is started.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the start of the next copy operation during the meandering correction during continuous copying can be performed at the timing when the meandering correction operation ends before the transfer paper of the copy reaches the thermal fixing device.

[0027]

[Effect of the device]

 As is apparent from the above description, according to the present invention, since the belt meandering correction operation is not performed when the sheet is in the thermal fixing device, it is not affected by the wrinkling of the belt due to the change of the belt tension. It is possible to perform heat fixing, and belt meandering correction can be performed regardless of image formation even during continuous copying operation, so that a good output image can always be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a copying machine according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit of the heat fixing device.

FIG. 3 is a flowchart of a meandering correction operation.

FIG. 4 is a perspective view showing a configuration of a conventional heat fixing device.

FIG. 5 is a perspective view for explaining a belt meandering correction operation of the thermal fixing device.

[Explanation of symbols]

 4 Thermal Fixing Device 6 Transfer Paper 17 Heat Roller 19 Nip Roller 20 Belt 21 Pulling Roller 31 Guide Shaft 36 Detection Sensor 38 Step Motor 39 Detection Sensor 44 CPU 46 Paper Sensor 47 Paper Sensor

Claims (2)

[Scope of utility model registration request] 1. A sheet having a plurality of rollers, a belt wound around the plurality of rollers, and a nip roller facing the rollers and being in pressure contact with the belt, the sheet having an image formed on the surface is conveyed by the belt. While having a heat fixing device for heating, meandering detection means for detecting the meandering of the belt, tension varying means for correcting the meandering by changing the tension at the left and right ends of the belt, and the meandering detecting means Drive means for driving the tension varying means in response to a signal; and control means for controlling the tension varying means when the sheet is in the thermal fixing device. Image forming apparatus. 2. The heat fixing according to claim 1, wherein when the meandering detection means detects meandering during continuous image forming operation, the start of the next image forming operation is delayed and the heat fixing is performed. An image forming apparatus, comprising: a control unit that opens a sheet interval entering the apparatus and controls to drive the tension varying unit during the sheet interval.