JP2011013591A - Device and program for control of belt winding angle, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt winding angle control device capable of suppressing cracks in a belt, to provide a belt winding angle control program, and to provide an image forming apparatus.SOLUTION: When a roll position controller 10 acquires the temperature T of a fixing belt 12f from a temperature measuring device 12g, the roll position controller 10 compares a predefined reference value TS with the temperature T of the fixing belt 12f and if T is lower than TS, the roll position controller moves the position of a winding angle control roll 12e to β1. At this point, the position of a heating roll 12a is at β2. Alternatively, if T is higher than TS, the roll position controller moves the position of the winding angle control roll 12e to α1. At this time, the position of the heating roll 12a is at α2.

Description

  The present invention relates to a belt winding angle control device, a belt winding angle control program, and an image forming apparatus.

  Japanese Patent Application Laid-Open Publication No. 2004-228561 discloses a technique for adjusting the fixing nip amount by adjusting the position of a roll on which a fixing belt is hung according to image forming conditions.

JP 2004-117518 A

  An object of the present invention is to provide a belt winding angle control device, a belt winding angle control program, and an image forming apparatus that can suppress the occurrence of cracks in the belt.

  In order to achieve the above object, the invention of the belt wrap angle control device according to claim 1 is characterized in that the temperature of a belt that is wound around a plurality of rolls and circulated while being heated is equal to or higher than a predetermined reference value. In this case, the wrapping angle of the minimum curvature radius portion of the belt in the belt circulation drive path is reduced.

  According to a second aspect of the present invention, the invention according to the first aspect includes a winding angle control roll for controlling a winding angle of a minimum curvature radius portion of the belt, and the winding angle control roll is a temperature of the belt. Is lower than a predetermined reference value, the winding angle is set to a first position where the winding angle is the first angle. When the belt temperature is equal to or higher than the reference value, the winding angle is set to the first position. It moves to the 2nd position made smaller than this angle, It is characterized by the above-mentioned.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the belt is hung according to the movement between the first position and the second position of the winding angle control roll. Tension control means for changing the position of the roll and controlling the tension of the belt is provided.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to third aspects, wherein the belt winding angle control device and the belt winding angle control device And a fixing belt in which a winding angle is controlled.

  The invention of the belt wrap angle control program according to claim 5 is characterized in that the wrap angle of the minimum curvature radius portion in the circulation drive path of the belt that is circulated and driven while being heated around a plurality of rolls. When the temperature of the belt to be controlled is lower than a predetermined reference value, the temperature of the belt is set to the first position where the winding angle is a first angle. When the value is greater than or equal to the value, the roll angle control unit is configured to move to a second position where the wrapping angle is smaller than the first angle.

  According to the first, fourth, and fifth aspects of the present invention, the occurrence of cracks in the belt can be suppressed as compared with the case where the present configuration is not provided.

  According to invention of Claim 2, compared with the case where it does not have this structure, the position of a winding angle control roll can be moved to the position which can suppress crack generation according to the temperature of a belt.

  According to invention of Claim 3, compared with the case where it does not have this structure, it can suppress that the tension | tensile_strength of a belt falls too much and a shift | offset | difference generate | occur | produces in the position where a belt engages with a roll.

1 is a diagram illustrating a configuration example of an image forming apparatus according to an embodiment. It is a figure which shows the example of the hardware constitutions of the computer which comprises the roll position control apparatus concerning embodiment. It is a functional block diagram of one embodiment of a roll position control device concerning an embodiment. It is a flowchart of the operation example of the roll position control apparatus concerning embodiment. It is a figure which shows the observation result of the crack which generate | occur | produces in the fixing belt 12f. It is a figure which shows the cross-section of the fixing belt 12f used for the crack generation test.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 shows a configuration example of an image forming apparatus according to the embodiment. In FIG. 1, the image forming apparatus includes a roll position control device 10, a fixing device 12, a paper feeding device 14, a development / transfer device 16, and a medium conveyance path 18.

  The roll position control device 10 controls the position of the roll constituting the fixing device 12, and controls the winding angle of the minimum radius of curvature portion in the circulation drive path of the fixing belt, as will be described later.

  The fixing device 12 includes a heating roll 12a, b, c, a pressure roll 12d, a winding angle control roll 12e, a fixing belt 12f, and a temperature measuring device 12g. The toner image received from the development / transfer device 16 A fixing process is performed by heating and pressurizing a medium such as printing paper on which the toner is transferred. By this fixing process, a toner image is formed on the medium.

  Here, the heating rolls 12a, 12b, and 12c are provided with heating means (not shown) (not shown) inside, and heat the fixing belt 12f. The pressure roll 12d sandwiches the fixing belt 12f and the medium conveyed by the medium conveyance path 18 between the heating roll 12b, and applies a fixing pressure to the medium. At this time, the medium is also heated by the fixing belt 12f. The fixing belt 12f is wound around the heating rolls 12a, 12b, and 12c and the winding angle control roll 12e, and is pressed in the direction of arrow C by the heating roll 12b that is rotationally driven by a drive motor (not shown). Circulation is driven at a moving speed equal to the peripheral speed of 12d. The temperature measuring device 12 g measures the temperature of the fixing belt 12 f and outputs the measurement result to the roll position control device 10.

  The roll position control device 10 controls the positions of the heating roll 12a and the winding angle control roll 12e based on the measurement output of the temperature measuring device 12g, and controls the shape of the circulation drive path of the fixing belt 12f. The heating roll 12a and the wrapping angle control roll 12e can be configured to move positions by appropriate actuators or the like, and the roll position control device 10 controls the position of each roll by controlling the actuator. Can be controlled. When the position of the winding angle control roll 12e moves in the direction of the arrow A1 in FIG. 1 (left and right direction in the figure), the winding angle θ1 of the fixing belt 12f wound around the winding angle control roll 12e also changes. For this reason, the roll position control device 10 can control the winding angle θ1 of the fixing belt 12f by controlling the position of the winding angle control roll 12e.

  Further, the roll position control device 10 moves the winding angle control roll 12e in the direction of arrow A1 in FIG. 1, and determines the angle at which the fixing belt 12f is sent from the heating roll 12b. In general, the angle between the fixing belt 12f and the direction perpendicular to the straight line connecting the rotation centers of the heating roll 12b and the pressure roll 12d is separated from the fixing belt 12f while maintaining the image quality of the fixing medium. Whether or not can be easily performed is determined. For this reason, the roll position control device 10 controls the position of the winding angle control roll 12e to determine the feed angle of the fixing belt 12f from the heating roll 12b. In the example of FIG. 1, when the winding angle control roll 12e is at the position α1, the medium and the fixing belt 12f can be easily separated. In this case, as shown by a solid line in FIG. 1, the shape of the circulation drive path of the fixing belt 12f is a shape in which a part of the ellipse is wound around and pulled out to the outside of the ellipse by the angle control roll 12e. The position of the contact angle control roll 12e is a minimum radius of curvature portion where the radius of curvature of the fixing belt 12f is minimum. At this time, the roll position control device 10 sets the position of the heating roll 12a to the position α2.

  On the other hand, immediately after the image forming apparatus is started, the temperature of the fixing belt 12f is about room temperature, and when the winding angle control roll 12e is at the position α1, the winding angle θ1 of the fixing belt 12f becomes a small angle. Therefore, if the circulation driving is performed in this state, the fixing belt 12f may crack. In particular, in a belt formed by laminating materials having different Young's moduli, cracks are more likely to occur. Therefore, when the temperature of the fixing belt 12f measured by the temperature measuring device 12g is lower than a predetermined reference value, the roll position control device 10 indicates the position of the winding angle control roll 12e as indicated by the broken line in FIG. Move to β1. As a result, the winding angle θ1 of the minimum curvature radius portion of the fixing belt 12f is made larger than when the winding angle control roll 12e is at the position α1. Further, at this time, the roll position control device 10 also moves the position of the heating roll 12a in the direction of the arrow A2 in FIG. 1 so that the broken line position β2 is controlled so that the tension acting on the fixing belt 12f does not decrease too much. .

  As described above, the roll position control device 10 moves the winding angle control roll 12e and the heating roll 12a between two positions (α1, β1) and (α2, β2) indicated by arrows A1 and A2, respectively. To control.

  The paper feeding device 14 holds a medium such as printing paper and supplies the medium to the developing / transferring device 16. The paper feeding device 14 may be configured to hold a plurality of types of media.

  The development / transfer device 16 forms an electrostatic latent image on the surface of a photosensitive drum (not shown) by a laser beam emitted in accordance with image data that is an object of image formation. , Developed as toner images of magenta, cyan, black, and transparent colors. The developed toner image is transferred to a medium. The medium on which the toner image is transferred is conveyed to the fixing device 12 through the medium conveyance path 18. It is also possible to adopt a configuration in which only black and white images are developed and transferred using black or black and transparent toner. Further, the acquisition of the image data includes a configuration in which the image data is acquired from an image creating apparatus such as a computer by an appropriate communication unit, and a configuration in which the image data is acquired by an image reading apparatus such as a scanner, but is not limited thereto. The development / transfer device 16 analyzes the acquired image data, determines the area on the image that uses the toner of each color, the type of toner to be used, the amount of use, and the like, and performs development processing and transfer processing.

  The medium conveyance path 18 includes an appropriate conveyance roll, belt, and the like, and conveys the medium on which the toner image is transferred from the development / transfer device 16 to the fixing device 12. Further, the fixing process is performed by the fixing device 12 and the medium on which the toner image is formed is discharged in the direction of the arrow P.

  FIG. 2 shows an example of a hardware configuration of a computer constituting the roll position control device according to the embodiment. In FIG. 2, the roll position control device includes a central processing unit (for example, a CPU such as a microprocessor may be used) 20, a random access memory (RAM) 22, a read only memory (ROM) 24, an input device 26, and a display device 28. And a hard disk device (HDD) 30. These components are connected to each other by a bus 32. The input device 26, the display device 28, and the hard disk device 30 are connected to the bus 32 via input / output interfaces 34a, 34b, and 34c, respectively.

  The CPU 20 controls the operation of each unit described below based on a control program stored in the RAM 22 or the ROM 24. The RAM 22 mainly functions as a work area for the CPU 20, and the ROM 24 stores a control program such as BIOS and other data used by the CPU 20.

  The input device 26 includes a keyboard, a pointing device, a touch panel, and the like, and is used by a user to input operation instructions and the like.

  The display device 28 includes a liquid crystal display, a touch panel, and the like, and displays a processing result by the CPU 20 and the like.

  The hard disk device 30 is a storage device, and stores various data necessary for processing to be described later. Instead of the hard disk device 30, a nonvolatile storage device such as an EEPROM may be used.

  FIG. 3 shows a functional block diagram of an embodiment of the roll position control device according to the embodiment. In FIG. 3, the roll position control device includes a belt temperature acquisition unit 36, a winding angle control unit 38, and a belt tension control unit 40, and these functions control, for example, the processing operations of the CPU 20 and the CPU 20. Realized by a program.

  The belt temperature acquisition unit 36 acquires the temperature of the fixing belt 12 f measured by the temperature measurement device 12 g and outputs the temperature to the wrapping angle control unit 38.

  The winding angle control unit 38 controls the winding angle θ1 of the minimum radius of curvature portion in the circulation drive path of the fixing belt 12f in accordance with the temperature of the fixing belt 12f acquired from the belt temperature acquisition unit 36. The position of the angle control roll 12e is determined. The winding angle control roll 12e moves to the position α1 or β1 determined by the winding angle control unit 38 along the arrow A1 in FIG.

  The belt tension control unit 40 controls the tension of the fixing belt 12f so that it does not drop below a certain value. The belt tension control unit 40 controls the heating roll 12a according to the position of the winding angle control roll 12e determined by the winding angle control unit 38. Determine the position. The heating roll 12a moves to the position α2 or β2 determined by the belt tension control unit 40 along the arrow A2 in FIG.

  FIG. 4 shows a flow of an operation example of the roll position control device according to the embodiment. In FIG. 4, when the belt temperature acquisition unit 36 acquires the temperature T of the fixing belt 12f from the temperature measuring device 12g (S1) and outputs the value of the temperature T to the winding angle control unit 38, the winding angle control unit 38 However, the predetermined reference value TS is compared with the temperature T of the fixing belt 12f (S2).

  In T2, when T is lower than TS (T <TS), the winding angle control unit 38 determines the position of the winding angle control roll 12e as β1 in FIG. 1 (S3). As a result, when the current position of the winding angle control roll 12e is α1 in FIG. 1, the winding angle control unit 38 controls an appropriate actuator that moves the winding angle control roll 12e, and the winding angle is controlled. The control roll 12e is moved to the position β1. On the other hand, when the current position of the winding angle control roll 12e is β1 in FIG. 1, no control signal is output to the actuator, and the current position is maintained. As a result, the winding angle θ1 around the winding angle control roll 12e of the fixing belt 12f becomes larger than when the winding angle control roll 12e is at the position α1.

  At this time, the belt tension controller 40 determines the position of the heating roll 12a as β2 in FIG. 1 (S4). As a result, when the current position of the heating roll 12a is α2 in FIG. 1, the belt tension control unit 40 controls an appropriate actuator that moves the heating roll 12a, and moves the heating roll 12a to the position β2. On the other hand, when the current position of the heating roll 12a is β2, a control signal is not output to the actuator, and the current position is maintained.

  On the other hand, in T2, when T is equal to or greater than TS (T ≧ TS), the winding angle control unit 38 determines the position of the winding angle control roll 12e as α1 (S5). As a result, when the current position of the winding angle control roll 12e is β1, the winding angle control unit 38 controls an appropriate actuator for moving the winding angle control roll 12e, and the winding angle control roll 12e. Is moved to position α1. On the other hand, when the current position of the winding angle control roll 12e is α1, a control signal is not output to the actuator, and the current position is maintained. As a result, the winding angle θ1 around the winding angle control roll 12e of the fixing belt 12f is smaller than when the winding angle control roll 12e is at the position β1.

  At this time, the belt tension controller 40 determines the position of the heating roll 12a as α2 (S6). As a result, when the current position of the heating roll 12a is β2, the belt tension control unit 40 controls an appropriate actuator that moves the heating roll 12a to move the heating roll 12a to the position α2. On the other hand, when the current position of the heating roll 12a is α2, a control signal is not output to the actuator, and the current position is maintained.

  The above-described program for executing each step in FIG. 4 can be stored in a recording medium, and the program may be provided by communication means. In that case, for example, the above-described program may be regarded as an invention of a “computer-readable recording medium recording a program” or an invention of a “data signal”.

  The above description uses the fixing belt 12f constituting the fixing device 12 as an example, but the embodiment is not limited to this, and the embodiment can be applied as long as the belt undergoes a temperature change during driving. .

  Hereinafter, specific examples of the above embodiment will be described as examples.

  5A and 5B show observation results of cracks generated in the fixing belt 12f. In any case, as a method for easily reproducing a crack that enters the fixing belt due to stress at the edge of the paper during continuous paper passing, a surface layer of the fixing belt 12f is scratched with a length of 1 mm, and the length of the growth is increased. Is observed. Note that small scratches on the surface layer of the fixing belt 12f hardly appear as gloss (gloss) unevenness on the image at the time of fixing, and even if they appear as gloss unevenness, they are not noticeable, but small scratches grow and become cracks of several centimeters. Further, not only the surface layer of the fixing belt 12f but also the intermediate layer is cracked, resulting in obvious image quality defects.

  FIG. 6 shows a cross-sectional structure of the fixing belt 12f used in the crack generation test in this embodiment. In FIG. 6, the fixing belt 12f has a three-layer structure, the base layer 42 is polyimide resin having a thickness of 80 μm, the intermediate layer 44 is silicon rubber having a thickness of 200 μm, and the surface layer 46 is 30 μm in thickness. It is composed of PFA (tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer resin).

  For the fixing belt 12f, the fixing device 12 shown in FIG. 1 was subjected to the operation described below with a tension of 8 kgf (78.4 N). The diameter of the heating roll 12a of the fixing device 12 was 65 mm, the diameter of the heating roll 12b was 65 mm, and the diameter of the heating roll 12c was 50 mm. The diameter of the pressure roll 12d was 65 mm. The winding angle control roll 12e had a diameter of 10 mm.

  In FIG. 5A, the position of the winding angle control roll 12e is set to the position β1 where the winding angle θ1 of the fixing belt 12f is large, and the fixing belt 12f is rotated at a moving speed of 440 mm / sec at room temperature (25 ° C.). And the comparative example in which the winding angle control roll 12e is set to a position α1 where the winding angle θ1 of the fixing belt 12f is small, and the fixing belt 12f is rotated at the same temperature and the same moving speed as the embodiment. Indicated.

  As shown in FIG. 5A, in the example in which the curvature of the fixing belt 12f is large, scratches hardly grow into cracks, but in the comparative example in which the curvature of the fixing belt 12f is small, the rotation speed (total) of the fixing belt 12f is large. The wound grows in proportion to the increase in the number of revolutions).

  In FIG. 5B, the position of the wrapping angle control roll 12e is set to a position α1 where the wrapping angle θ1 of the fixing belt 12f is small, and the moving speeds are 440 mm / sec and 220 mm / 220 at a temperature of 25 ° C of the fixing belt 12f. It is an observation result of scratch growth when rotating in seconds. In this case, scratches grow in proportion to an increase in the rotation speed (total rotation speed) of the fixing belt 12f regardless of the moving speed of the fixing belt 12f. From this, it can be seen that until the surface of the fixing belt reaches a predetermined temperature, even if it is rotated slowly, it becomes a crack, and the crack cannot be avoided unless the stress of curvature is removed.

  As described above, when the fixing belt 12f is rotated at room temperature (25 ° C.), the flaw of the fixing belt 12f grows regardless of the moving speed of the fixing belt 12f, but by increasing the winding angle θ1 of the fixing belt 12f. It can be seen that the growth of the wound can be suppressed. When the fixing belt 12f was similarly rotated at a temperature of 140 ° C., no flaw growth was observed when the winding angle control roll 12e was either α1 or β1. Accordingly, it is preferable to set an appropriate temperature (for example, 140 ° C.) higher than the room temperature as the reference value, and to control the position of the winding angle control roll 12e to be the position α1 after the temperature becomes higher than the reference value. It is.

  10 roll position control device, 12 fixing device, 12a, 12b, 12c heating roll, 12d pressure roll, 12e winding angle control roll, 12f fixing belt, 12g temperature measuring device, 14 paper feeding device, 16 developing / transfer device, 18 Media transport path, 20 CPU, 22 RAM, 24 ROM, 26 Input device, 28 Display device, 30 Hard disk device, 32 Bus, 34a, 34b, 34c Input / output interface, 36 Belt temperature acquisition unit, 38 Winding angle control unit , 40 belt tension control unit, 42 base layer, 44 intermediate layer, 46 surface layer.

Claims (5)

  When the temperature of a belt that is wound around a plurality of rolls and heated while being circulated is equal to or higher than a predetermined reference value, the winding angle of the minimum curvature radius portion of the belt in the circulation driving path of the belt is determined. A belt winding angle control device characterized in that the belt winding angle is reduced.   The belt winding angle control device according to claim 1, further comprising a winding angle control roll that controls a winding angle of a minimum curvature radius portion of the belt, and the winding angle control roll has a temperature of the belt in advance. When the temperature is lower than a predetermined reference value, the winding angle is set to a first position where the winding angle is the first angle. When the temperature of the belt is equal to or higher than the reference value, the winding angle is set to the first angle. A belt winding angle control device, wherein the belt winding angle control device moves to a second position to be made smaller.   The belt wrap angle control device according to claim 1 or 2, wherein the wrap angle control roll of another roll on which the belt is hung according to the movement between the first position and the second position of the wrap angle control roll. A belt winding angle control device comprising tension control means for changing the position and controlling the tension of the belt. The belt winding angle control device according to any one of claims 1 to 3,
A fixing belt in which the winding angle of the minimum curvature radius portion is controlled by the belt winding angle control device;
An image forming apparatus comprising: Computer
The temperature of the belt pre-determines the position of the winding angle control roll that controls the winding angle of the minimum radius of curvature portion in the circulation drive path of the belt that is wound around a plurality of rolls and heated and circulated. When the belt temperature is lower than the reference value, the winding angle is set to a first position where the winding angle is the first angle. When the belt temperature is equal to or higher than the reference value, the winding angle is smaller than the first angle. A roll winding angle control program that functions as roll position control means for moving to a second position.

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