JP2012048087A - Fixing apparatus, image forming apparatus, and heater control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently suppress the occurrence of wrinkles on a fixing belt included in a fixing apparatus.SOLUTION: During the operation adjustment of a fixing apparatus that fixes toner on paper by the heat of an endless fixing belt heated in a rotating state by a heater lamp 50, a rotation detection part 204 detects whether or not the fixing belt is rotating. If the rotation detection part 204 detects that the fixing belt is rotating, a heater control part 205 turns on the heater lamp 50 to prevent the occurrence of wrinkles.

Description

  The present invention relates to a fixing device that fixes toner on paper by heat of an endless fixing belt that is heated by a heater while being rotated, an image forming apparatus, and a heater control method in which the fixing device controls the heater.

  Conventional image forming apparatuses using an electrophotographic process such as a copying machine, a multifunction peripheral (MFP), a printer, and a facsimile are provided with a fixing device for fixing toner on paper by applying heat and pressure. (For example, see Patent Document 1).

  This fixing device has a fixing roller and a heating roller, and the fixing roller and the heating roller are connected by an endless fixing belt. The fixing roller presses the heated fixing belt against the paper to fix the toner on the paper. The heating roller includes a heater lamp and supplies heat to the fixing belt.

JP 2008-170649 A

  However, in the above-described prior art, when the heater lamp is turned on when the fixing belt is not driven, the temperature of the portion of the fixing belt that is in contact with the heating roller suddenly rises, and the fixing belt that is in contact with the heating roller There is a problem that the temperature differs between this portion and the portion of the fixing belt that is not in contact therewith, and wrinkles are generated in the fixing belt. For example, it is known that wrinkles occur in about 10 seconds when the heater lamp is turned on when the fixing belt is not driven.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device, an image forming apparatus, and a heater control method capable of effectively suppressing generation of wrinkles on a fixing belt.

  In order to solve the above problems, a first technical means of the present invention is a fixing device that fixes toner on paper by the heat of an endless fixing belt heated by a heater while rotating, and the operation of the fixing device A rotation detection unit that detects rotation of the fixing belt at the time of adjustment; and a heater control unit that turns on the heater when rotation of the fixing belt is detected by the rotation detection unit. Is.

  According to a second technical means of the present invention, in the first technical means, when rotation of the fixing belt is not detected by the rotation detecting unit during operation adjustment, the fixing device is restarted, and the rotation detecting unit When the rotation of the fixing belt is detected, the heater control unit turns on the heater.

  According to a third technical means of the present invention, the first or second technical means further includes a temperature sensor for detecting a temperature in the fixing device, and the heater control unit rotates the fixing belt by the rotation detection unit. Is detected, and when the temperature rise exceeds a predetermined value by the temperature sensor, the heater is turned off.

  According to a fourth technical means of the present invention, in the third technical means, the predetermined value is 70 ° C.

  According to a fifth technical means of the present invention, in any one of the first to fourth technical means, the rotation detection unit rotates the fixing belt while the heater is turned on when the fixing device is on standby. Is not detected for a predetermined period of time, the apparatus further comprises a rotation control section for rotating the fixing belt by a predetermined angle.

  According to a sixth technical means of the present invention, in the fifth technical means, a heating roller for supporting the fixing belt from the inside of the fixing belt and heating the fixing belt from the inside by heat generated by the heater. In addition, the predetermined angle is an angle formed by two straight lines lowered from both ends of a contact portion between the heating roller and the fixing belt toward the center of the heating roller.

  According to a seventh technical means of the present invention, the image forming apparatus includes a fixing device according to any one of the first to sixth technical means.

  An eighth technical means of the present invention is a heater control method in which a fixing device that fixes toner on paper by heat of an endless fixing belt heated by a heater while being rotated controls the heater. A rotation detecting step for detecting rotation of the fixing belt during operation adjustment, and a heater control step for turning on the heater when rotation of the fixing belt is detected by the rotation detecting step. It is a thing.

  According to the present invention, when the rotation of the fixing belt is detected at the time of adjusting the operation of the fixing device, the heater is appropriately turned on, so that the occurrence of wrinkles on the fixing belt can be effectively suppressed.

1 is a schematic diagram illustrating an example when a fixing device according to an exemplary embodiment is applied to an image forming apparatus. 1 is a schematic view of a fixing device. 3 is a functional block diagram of a wrinkle suppressing unit provided in the image forming apparatus. FIG. It is a figure which shows the result of a wrinkle generation | occurrence | production experiment. 6 is a conceptual diagram illustrating rotation control processing of a fixing roller. FIG. It is a flowchart explaining an example of the process sequence of the heater lamp lighting control process which concerns on this embodiment. 6 is a flowchart illustrating an example of a processing procedure of fixing roller rotation control processing according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram illustrating an example in which the fixing device according to the present embodiment is applied to an image forming apparatus 100. The image forming apparatus 100 includes an original reading apparatus A that reads an image of an original, and an apparatus main body B that forms an image of the original read by the original reading apparatus A or an image received from the outside in color or single color on a recording sheet. I have.

  The document reader A of the image forming apparatus 100 includes a document set tray 1, a pickup roller 2, a roller roller 3, a separation pad 4, a conveyance path 5, a registration roller 6, a reading guide 7, a reading glass 8, a first scanning unit 9, A second scanning unit 10, an imaging lens 11, a CCD (Charge Coupled Device) 12, a transport roller 13, a paper discharge roller 14, a paper discharge tray 15, and a document table glass 16 are provided.

  When the document is set on the document set tray 1, the pickup roller 2 is pressed against the document surface. Then, the document is pulled out from the tray 1 by the rotation of the pickup roller 2. Thereafter, the document passes between the roller roller 3 and the separation pad 4 and is separated one by one before being conveyed to the conveyance path 5.

  In the transport path 5, the leading edge of the document contacts the registration roller 6, and the leading edge is aligned in parallel with the registration roller 6. Then, the document is conveyed by the registration roller 6 and passes between the reading guide 7 and the reading glass 8. At this time, the light of the light source provided in the first scanning unit 9 is irradiated on the surface of the original through the reading glass 8, and the reflected light enters the first scanning unit 9 through the reading glass 8. The reflected light is reflected by the mirrors provided in the first scanning unit 9 and the second scanning unit 10 and guided to the imaging lens 11. Then, the image of the original is imaged on a CCD (Charge Coupled Device) 12 by the imaging lens 11. The CCD 12 reads a document image and outputs image data indicating the document image. Further, the document is transported by the transport roller 13 and discharged to the paper discharge tray 15 via the paper discharge roller 14.

  Further, the image forming apparatus 100 can read a document placed on the document table glass 16. The registration roller 6, the reading guide 7, the paper discharge tray 15, and the like and the members above them are integrated, and they form a cover body that is pivotally supported on the back side of the document reading apparatus A so as to be opened and closed. . When the cover body is opened, the document table glass 16 is released, and a document can be placed on the document table glass 16.

  When the document is placed and the cover is closed, the first scanning unit 9 and the second scanning unit 10 move in the sub-scanning direction, and the first scanning unit 9 exposes the document surface on the document table glass 16. . Reflected light from the document surface is guided to the imaging lens 11 by the first scanning unit 9 and the second scanning unit 10, and an image of the document is formed on the CCD 12 by the imaging lens 11. At this time, the first scanning unit 9 and the second scanning unit 10 move while maintaining a predetermined speed relationship with each other.

  Specifically, the first scanning unit 9 and the second scanning unit 9 and the second scanning unit 10 and the first scanning unit 9 and the second scanning unit 10 so that the optical path length of the reflected light from the document surface through the imaging lens 11 to the CCD 12 does not change. The positional relationship between the two scanning units 10 is always maintained. Thereby, the focus of the image of the document on the CCD 12 is always maintained accurately. The entire original image read in this way is transmitted as image data to the apparatus main body B of the image forming apparatus, and the apparatus main body B records the image on a recording sheet.

  The apparatus main body B of the image forming apparatus 100 includes a laser exposure device 20, developing devices 21a to 21d, photosensitive drums 22a to 22d, chargers 23a to 23d, cleaner devices 24a to 24d, an intermediate transfer belt device 27, a fixing device 31, A paper transport device 32, a paper feed tray 33, and a paper discharge tray 34 are provided.

  The image data handled in the image forming apparatus 100 uses data corresponding to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color (for example, black). This corresponds to a monochrome image. Accordingly, the developing devices 21a to 21d, the photoconductor drums 22a to 22d, the chargers 23a to 23d, and the cleaner devices 24a to 24d are provided four by four so as to form four types of latent images corresponding to the respective colors. Four image stations are formed by associating a with black, b with cyan, c with magenta, and d with yellow.

  The photoconductor drums 22a to 22d are drums whose surfaces are charged to a predetermined potential, and are arranged at substantially the center of the apparatus main body B. The chargers 23a to 23d are charging units that uniformly charge the surfaces of the photosensitive drums 22a to 22d to a predetermined potential. The chargers 23a to 23d include a charger type charger as well as a contact type roller type and brush type charger.

  The laser exposure apparatus 20 is a laser scanning unit (LSU) provided with a laser diode and a reflection mirror. The laser exposure apparatus 20 exposes the surfaces of the charged photosensitive drums 22a to 22d according to image data, and forms an electrostatic latent image according to the image data on the surface.

  The developing devices 21a to 21d develop the electrostatic latent images formed on the photosensitive drums 22a to 22d with black (K), cyan (C), magenta (M), and yellow (Y) toners. The cleaners 24a to 24d remove and collect toner remaining on the surfaces of the photosensitive drums 22a to 22d after development and image transfer.

  The intermediate transfer belt device 27 disposed above the photosensitive drums 22a to 22d includes an intermediate transfer belt 26, an intermediate transfer belt driving roller 28, a driven roller 29, intermediate transfer rollers 25a to 25d, and an intermediate transfer belt cleaning device. 30.

  The intermediate transfer belt drive roller 28, the intermediate transfer rollers 25 a to 25 d, and the driven roller 29 stretch and support the intermediate transfer belt 26 and move the intermediate transfer belt 26 in the direction of arrow C. The intermediate transfer rollers 25a to 25d are rotatably supported in the vicinity of the intermediate transfer belt 26. The intermediate transfer rollers 25a to 25d are pressed against the photosensitive drums 22a to 22d via the intermediate transfer belt 26, and apply a transfer bias for transferring the toner images on the photosensitive drums 22a to 22d to the intermediate transfer belt 26. To do.

  The intermediate transfer belt 26 is provided so as to be in contact with the respective photosensitive drums 22a to 22d, and the toner images on the surfaces of the respective photosensitive drums 22a to 22d are sequentially superimposed and transferred onto the intermediate transfer belt 26, so that color Toner images (toner images of respective colors) are formed. The intermediate transfer belt 26 is formed in an endless belt shape using a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drums 22 a to 22 d to the intermediate transfer belt 26 is performed by intermediate transfer rollers 25 a to 25 d that are pressed against the back surface of the intermediate transfer belt 26. A high-voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (-)) is applied to the intermediate transfer rollers 25a to 25d in order to transfer the toner image. The intermediate transfer rollers 25a to 25d are based on a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm, and the surface thereof is covered with a conductive elastic material (for example, EPDM (Ethylene Propylene Diene Monomer), foamed urethane, etc.). ing. By this conductive elastic material, a high voltage can be uniformly applied to the recording paper.

  The toner images on the surfaces of the photosensitive drums 22a to 22d are stacked by the intermediate transfer belt 26, and become a color toner image indicated by the image data. The toner images of the respective colors stacked in this manner are transported together with the intermediate transfer belt 26 and transferred onto the recording paper by the secondary transfer device 35 that contacts the intermediate transfer belt 26.

  The intermediate transfer belt 26 and the transfer roller 35a included in the secondary transfer device 35 are pressed against each other to form a nip region. Further, a voltage (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) for transferring the toner image of each color on the intermediate transfer belt 26 onto the recording paper is applied to the transfer roller 35a. . Further, in order to constantly obtain the nip region, either the transfer roller 35a or the intermediate transfer belt drive roller 28 is made of a hard material (metal or the like), and the other is a soft material such as an elastic roller (elastic rubber roller or , Foaming resin roller, etc.).

  Note that the toner image on the intermediate transfer belt 26 may not be completely transferred onto the recording paper by the secondary transfer device 35, and the toner may remain on the intermediate transfer belt 26. Cause color mixing. Therefore, the intermediate transfer belt cleaning device 30 removes and collects residual toner. The intermediate transfer belt cleaning device 30 is provided with, for example, a cleaning blade that contacts the intermediate transfer belt 26 as a cleaning member, and the back side of the intermediate transfer belt 26 is supported by a driven roller 29 at a portion where the cleaning blade contacts. ing.

  The paper feed tray 33 is a tray for storing recording paper, and is provided below the image forming unit of the apparatus main body B. A paper discharge tray 34 provided on the upper side of the image forming unit is a tray for placing printed recording paper face down.

  Further, the apparatus main body B is provided with a paper transport device 32 for sending the recording paper in the paper feed tray 33 to the paper discharge tray 34 via the secondary transfer device 35 and the fixing device 31. The sheet conveying device 32 has an S-shaped sheet conveying path S, and along the sheet conveying path S, a pickup roller 36, a registration roller 37, a fixing device 31, each conveying roller 38a to 38d, and a pre-registration roller. 39 and a paper discharge roller 40 are disposed.

  The pickup roller 36 is a pull-in roller that is provided at the end of the paper feed tray 33 and supplies recording paper from the paper feed tray 33 to the paper transport path S one by one. Each of the transport rollers 38a to 38d is a small roller for promoting and assisting the transport of the recording paper, and is provided at a plurality of locations along the paper transport path S.

  The registration roller 37 temporarily stops the recording paper that has been conveyed, aligns the leading edge of the recording paper, and a color toner image on the intermediate transfer belt 26 in the nip area between the intermediate transfer belt 26 and the secondary transfer device 35. The recording paper is conveyed in a timely manner in accordance with the rotation of the photosensitive drums 22a to 22d and the intermediate transfer belt 26 so that is transferred onto the recording paper.

  The fixing device 31 receives the recording sheet on which the toner image has been transferred, and sandwiches and conveys the recording sheet in a nip area between the fixing belt 41 and the pressure roller 42. The fixing device 31 heats and pressurizes the recording paper to fix the toner image on the recording paper. The fixing belt 41 is an endless belt stretched between the fixing roller 43 and the heating roller 44. For the fixing belt 41, for example, an organic material having low thermal conductivity (for example, a resin material, heat-resistant polyimide, or the like) is used as a base material. For example, polyimide is used for the base material of the fixing belt 41, and a silicon rubber layer and a fluororesin layer are laminated thereon to form the fixing belt 41 having a three-layer structure. In general, organic materials have low thermal conductivity and a high linear expansion coefficient. Therefore, it is considered that a temperature difference is likely to occur in the fixing belt 41 and wrinkles are likely to occur. However, by using the fixing device 31 described in detail later, The generation of wrinkles can be effectively suppressed.

  The fixing roller 43 is a roller for fixing toner on the recording paper. The heating roller 44 includes a heater lamp (halogen lamp) and supplies heat generated by the heater lamp to the fixing belt 41. The fixing belt 41 heated by the heat of the heater lamp heats the recording paper and fixes the toner image. Here, the fixing belt 41 is heated by a heater using a halogen lamp as a heat source. However, the fixing belt 41 may be heated by a heater using another heat source. The recording paper after the toner images of the respective colors are fixed is discharged onto the paper discharge tray 34 by the paper discharge roller 40.

  It is also possible to form a monochrome image using only one image forming station and transfer the monochrome image to the intermediate transfer belt 26. Similar to the color image, this monochrome image is also transferred from the intermediate transfer belt 26 to the recording paper and fixed on the recording paper.

  In addition, when printing on both sides of the recording paper, not only the surface of the recording paper, but also after the fixing device 31 fixes the image on the surface of the recording paper, the recording paper is being transported by the paper discharge roller 40 in the paper transport path S. Then, the paper discharge roller 40 is stopped and then reversely rotated. Then, the recording sheet is passed through the reversing path Sr, and the front and back are reversed, and then guided to the registration roller 37. Thereafter, similarly to the front surface of the recording paper, an image is recorded and fixed on the back surface of the recording paper, and the recording paper is discharged to the paper discharge tray 34.

  Next, the fixing device 31 of this embodiment will be described. FIG. 2 is a schematic diagram of the fixing device 31. As shown in FIG. 2, the fixing device 31 includes a fixing roller 43, a pressure roller 42, a heating roller 44, and an endless fixing belt 41 that is stretched between the fixing roller 43 and the heating roller 44. ing. In the fixing device 31, the pressure roller 42 is pressed against the fixing roller 43 via the fixing belt 41, and a nip region N is formed between the fixing belt 41 and the pressure roller 42.

  In a state where the fixing device 31 is mounted on the apparatus main body B of the image forming apparatus 100, the gear (not shown) of the driving mechanism on the apparatus main body B side meshes with the gear (not shown) of the shaft of the fixing roller 43, The rotational driving force from the drive mechanism on the apparatus main body B side is transmitted to the shaft of the fixing roller 43, and the fixing roller 43 is rotationally driven. With the rotation of the fixing roller 43, the heating roller 44 and the fixing belt 41 rotate in the same direction as the fixing roller 43, and the pressure roller 42 is driven to rotate. The recording paper is nipped and conveyed in a nip area N between the fixing belt 41 and the pressure roller 42, and is heated and pressurized. As a result, the toner image on the recording paper is melted, mixed, and pressed to be thermally fixed.

  The fixing roller 43 is a roller having a three-layer structure in which an elastic layer is provided on the outer surface of the core metal and a release layer is formed on the outer surface of the elastic layer. For the core metal, for example, a metal such as iron, stainless steel, aluminum, copper, or an alloy thereof is used. Silicon rubber is used for the elastic layer, and the release layer is made of fluororesin such as PFA (Perfluoroalkoxy, a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) or PTFE (Polytetrafluoroethylene). Used.

  A heater lamp 50 serving as a heat source for heating the heating roller 44 is provided inside the heating roller 44 (inside the cored bar). The heat of the heating roller 44 is conducted to the fixing roller 43 through the fixing belt 41, and heat is supplied to the fixing roller 43.

  Similar to the fixing roller 43, the pressure roller 42 is a metal core made of metal such as iron, stainless steel, aluminum, copper, or an alloy thereof, an elastic layer such as silicon rubber on the surface of the metal core, and further thereon. It is a three-layered roller composed of a release layer such as PFA or PTFE.

  Thus, the elastic layer is provided on the pressure roller 42 and the fixing roller 43, and the pressure roller 42 is pressed against the fixing roller 43. Therefore, the width of the nip area between the fixing belt 41 and the pressure roller 42 is widened. can do.

  Next, the wrinkle suppression process of the fixing belt 41 performed by the image forming apparatus 100 according to the present embodiment will be described. FIG. 3 is a functional block diagram of the wrinkle suppressing unit 200 provided in the image forming apparatus 100. The wrinkle suppression unit 200 includes a time measurement unit 201, a temperature sensor 202, a storage unit 203, a rotation detection unit 204, a heater control unit 205, and a rotation control unit 206.

  The time measuring unit 201 measures a time during which the fixing belt 41 is not rotating. For example, when the image forming apparatus 100 is not performing a job for forming an image on recording paper, the fixing belt 41 does not rotate, so the time measuring unit 201 measures the time. The temperature sensor 202 is a sensor that measures the ambient temperature in the fixing device 31. The storage unit 203 is a storage device such as a memory or a hard disk device. The storage unit 203 stores information on the time measured by the time measurement unit 201, information on the temperature measured by the temperature sensor 202, and the like.

  The rotation detection unit 204 detects whether the fixing belt 41 is rotating by detecting the rotation of the fixing roller 43. Note that the rotation detection unit 204 may detect the rotation of the fixing belt 41 using another method such as detecting the rotation of the heating roller 44.

  The heater control unit 205 controls lighting of the heater lamp 50 when the image forming apparatus 100 performs a job for forming an image on recording paper. In the operation adjustment process of the image forming apparatus 100 before performing the job, the heater control unit 205 is configured to turn on the heater lamp 50 when the rotation detection unit 204 does not detect the rotation of the fixing roller 43. Even when an instruction is received from the control unit 60 that controls the image forming process, the heater lamp 50 is not turned on. In this case, the heater control unit 205 requests the control unit 60 of the image forming apparatus 100 to restart the image forming apparatus 100. When the rotation of the fixing roller 43 is detected in the operation adjustment process of the image forming apparatus 100 after the restart, the heater control unit 205 turns on the heater lamp 50.

  Further, the heater control unit 205 receives information on the atmospheric temperature in the fixing device 31 detected by the temperature sensor 202 from the storage unit 203, and after the heater lamp 50 is turned on when the operation of the image forming apparatus 100 is adjusted. It is determined whether the temperature rise exceeds a predetermined value. The heater controller 205 turns off the heater lamp 50 when the temperature rise exceeds a predetermined value.

  The wrinkles of the fixing belt 41 are generated in various directions due to the temperature difference between the high temperature region and the low temperature region of the fixing belt 41. FIG. 4 is a diagram showing the results of a wrinkle generation experiment. In this experiment, the temperature of the fixing belt 41 on the heating roller 44 when the heater lamp 50 was turned on without rotating the fixing belt 41 was measured. In the drawing, C indicates the temperature of the central portion of the fixing belt 41, and F indicates the fixing at a position 105 mm away from C on the front side of the image forming apparatus 100 (the front side of the image forming apparatus 100 shown in FIG. 1). The temperature of the belt 41 is indicated, and R indicates the temperature of the fixing belt 41 at a position 140 mm away from C on the back side of the image forming apparatus 100 (the back side of the paper surface of the image forming apparatus 100 shown in FIG. 1).

  4A and 4B show experimental results of the fixing belt 41 manufactured by different manufacturers. In these examples, a heater lamp 50 of 1250 W is used. The fixing belt 41 shown in FIG. 4A has temperatures of 24.5 ° C., 23.5 ° C., and 23.6 ° C. at the respective positions F, C, and R at the start of lighting of the heater lamp 50. The temperatures at the time when the occurrence of wrinkles was confirmed were 110.4 ° C., 119.1 ° C., and 130.4 ° C. at the positions of F, C, and R, respectively. The temperature difference from the temperature at the time when the occurrence of the occurrence is confirmed is 85.9 ° C., 95.6 ° C., and 106.8 ° C. at the respective positions of F, C, and R. Similarly, with respect to the fixing belt 41 in FIG. 4B, the temperature difference is 48.2 ° C., 75.6 ° C., and 84 ° C. at the respective positions of F, C, and R. Here, the temperature is different at the positions F, C, and R because the heat generation distribution of the heating roller 44 changes along the rotation axis direction of the heating roller 44. This heat generation distribution is determined according to the size of the recording paper, the range where the fixing belt 41 is in contact with the recording paper, the state of heat radiation of the heating roller 44, and the like.

  FIG. 4C shows the temperature of the fixing belt 41 when the heater lamp 50 is turned on from room temperature. FIG. 4D shows the heater lamp in the image forming apparatus 100 in a standby state. The temperature of the fixing belt 41 when 50 is turned on is shown. In these examples, a heater lamp 50 of 725 W is used. In FIG. 4C, the temperature difference between the temperature at the start of lighting of the heater lamp 50 and the temperature at the time when the generation of wrinkles is visually confirmed is 56.1 ° C., 101. 5 ° C and 42.2 ° C. In FIG. 4D, the temperature difference is 91.2 ° C., 136.5 ° C., and 54.1 ° C. at the respective positions of F, C, and R.

  From the above experimental results, it can be seen that wrinkles are generated in the fixing belt 41 when the temperature rises around 100 ° C. (average value of about 81.5 ° C.) from the temperature at which the heater lamp 50 starts to light in any situation. For this reason, the heater control unit 205 turns off the heater lamp 50 when, for example, the increase in the ambient temperature in the fixing device 31 exceeds about 70 ° C., and wrinkles occur in the fixing belt 41. Effectively suppress.

  The rotation control unit 206 controls the rotation of the fixing roller 43 when the image forming apparatus 100 performs a job for forming an image on recording paper. In addition, the rotation control unit 206 acquires information on the time measured by the time measuring unit 201 from the storage unit 203, the image forming apparatus 100 is in a standby state, the heater lamp 50 is turned on, and the fixing belt. When 41 is not driven within a predetermined time in the past (for example, within the past 10 minutes), the fixing roller 43 is controlled to rotate by a predetermined angle α.

  FIG. 5 is a conceptual diagram illustrating the rotation control process of the fixing roller 43. As shown in FIG. 5, when the fixing roller 43 is not driven, the fixing belt 41 and the heating roller 44 are stopped. When the heater lamp 50 of the heating roller 44 is turned on in this state, the contact portion 51 between the fixing belt 41 and the heating roller 44 is heated, and the temperature difference between the contact portion 51 of the fixing belt 41 and other portions is large. As a result, the fixing belt 41 is wrinkled.

  Therefore, when the rotation detection unit 204 determines that the image forming apparatus 100 is in a standby state and the fixing belt 41 has not been driven within a predetermined time in the past, the rotation control unit 206 determines the fixing roller 43. Is controlled to rotate by a predetermined angle. For example, as shown in FIG. 5, the rotation angle is set to an angle α formed by two straight lines lowered from both ends of the contact portion 51 between the fixing belt 41 and the heating roller 44 toward the center of the heating roller 44. As a result, the portion of the fixing belt 41 that has been in contact with the heating roller 44 is no longer in contact with the heating roller 44, so that only that portion of the fixing belt 41 is suppressed from being heated. If the portion of the fixing belt 41 that has been in contact with the heating roller 44 is no longer in contact with the heating roller 44, the fixing roller 43 may be rotated at an angle greater than α.

  Below, an example of the process sequence of the heater lamp lighting control process which concerns on this embodiment is demonstrated. FIG. 6 is a flowchart for explaining an example of the processing procedure of the heater lamp lighting control processing according to the present embodiment. As shown in FIG. 6, the heater control unit 205 of the image forming apparatus 100 receives a signal for requesting lighting of the heater lamp from the control unit 60 of the image forming apparatus 100 in the operation adjustment process of the image forming apparatus 100 (step S101).

  Then, the rotation detection unit 204 detects whether or not the fixing roller 43 rotates (step S102). If rotation of the fixing roller 43 is not detected (NO in step S102), the heater control unit 205 determines that the heater lamp 50 cannot be turned on and does not turn on the heater lamp 50 (step S103). Thereafter, the heater control unit 205 requests the control unit 60 of the image forming apparatus 100 to restart the image forming apparatus 100 (step S104). In the operation adjustment process of the image forming apparatus 100 after the restart, the heater control unit 205 receives again a signal requesting the lighting of the heater lamp 50 from the control unit 60 of the image forming apparatus 100 (step S101). Continue processing.

  When rotation of the fixing roller 43 is detected (YES in step S102), the heater control unit 205 turns on the heater lamp 50 (step S105). The temperature sensor 202 detects the ambient temperature in the fixing device 31 (step S106). Thereafter, the heater control unit 205 receives information on the ambient temperature detected by the temperature sensor 202, and determines whether or not the temperature rise after the heater lamp 50 is turned on exceeds a predetermined value (for example, 70 ° C.). (Step S107).

  If the temperature rise does not exceed the predetermined value (NO in step S107), the temperature sensor 202 waits for a predetermined time, detects the ambient temperature in the fixing device 31 again (step S106), and the subsequent processing Continue. If the temperature rise exceeds a predetermined value (YES in step S107), heater control unit 205 turns off heater lamp 50 (step S108).

  Thereafter, the temperature sensor 202 detects the ambient temperature in the fixing device 31 again (step S109). The heater control unit 205 receives the information on the ambient temperature detected by the temperature sensor 202, and determines whether or not the temperature rise after the heater lamp 50 is turned on falls below a predetermined value (step S110). For example, it is desirable that the predetermined value is such that the ambient temperature does not immediately exceed 70 ° C. even when the heater lamp 50 is turned on again.

  If the temperature rise is not lower than the predetermined value (NO in step S110), the temperature sensor 202 waits for a predetermined time, detects the ambient temperature in the fixing device 31 again (step S109), and the subsequent processing. Continue. When the temperature rise falls below a predetermined value (YES in step S110), heater control unit 205 turns on heater lamp 50 (step S105) and continues the subsequent processing.

  Next, an example of a processing procedure of fixing roller rotation control processing according to the present embodiment will be described. FIG. 7 is a flowchart for explaining an example of the processing procedure of the fixing roller rotation control processing according to the present embodiment. As illustrated in FIG. 7, when the heater control unit 205 of the image forming apparatus 100 receives a notification from the control unit 60 of the image forming apparatus 100 that the image forming apparatus 100 shifts to a standby state, To maintain the temperature, the heater lamp 50 is turned on (step S201).

  Thereafter, the time measuring unit 201 determines whether or not the fixing belt 41 has been driven within a predetermined time in the past (for example, within 10 minutes) based on the information on the presence or absence of rotation of the fixing roller 43 (step S202). . Information on the presence or absence of rotation of the fixing roller 43 is output by the rotation detection unit 204. If the fixing belt 41 has not been driven within a predetermined time (NO in step S202), the rotation control unit 206 rotates the fixing roller 43 by a predetermined angle (step S203).

  For example, as shown in FIG. 5, the rotation control unit 206 is configured to fix the fixing roller by an angle α formed by two straight lines lowered from both ends of the contact portion 51 between the fixing belt 41 and the heating roller 44 toward the center of the heating roller 44. 43 is rotated. When the fixing roller 43 rotates, the heating roller 44 and the fixing belt 41 rotate in the same direction as the fixing roller 43. Thereby, it is possible to prevent only a part of the fixing belt 41 from being heated, and to prevent the fixing belt 41 from wrinkling.

  Thereafter, the rotation control unit 206 checks whether or not to continue the standby state (step S204). Specifically, when the rotation control unit 206 has not received a notification from the control unit 60 of the image forming apparatus 100 that the image forming apparatus 100 cancels the standby state, the rotation control unit 206 determines to continue the standby state, and sets the standby state. When the notification to cancel is received, it is determined that the standby state is ended. If the standby state is not continued (NO in step S204), the fixing roller rotation process ends. When the standby state is continued (YES in step S204), the time measuring unit 201 determines again whether or not the fixing belt 41 has been driven within the past predetermined time (step S202).

  When the fixing belt 41 is driven within the predetermined time (YES in step S202), the rotation control unit 206 checks whether or not the standby state is continued (step S204), and performs subsequent processing.

  As described above, the fixing device 31 and the image forming apparatus 100 according to the present embodiment appropriately turn on the heater lamp 50 when rotation of the fixing belt 41 is detected during operation adjustment of the fixing device 31. The occurrence of wrinkles in the fixing belt 41 can be effectively suppressed. Note that the present invention is not limited to the above-described embodiment, and various modifications and corrections are possible without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Document set tray, 2 ... Pick-up roller, 3 ... Sabaki roller, 4 ... Separation pad, 5 ... Conveyance path, 6 ... Registration roller, 7 ... Reading guide, 8 ... Reading glass, 9 ... 1st scanning part, 10 ... Second scanning unit 11 ... imaging lens, 12 ... CCD, 13 ... conveying roller, 14 ... discharge roller, 15 ... discharge tray, 16 ... document glass, 100 ... image forming apparatus, 20 ... laser exposure apparatus, 21a to 21d ... developing device, 22a to 22d ... photosensitive drum, 23a-23d ... charger, 24a-24d ... cleaner device, 25a-25d ... intermediate transfer roller, 26 ... intermediate transfer belt, 27 ... intermediate transfer belt device, 28 ... Intermediate transfer belt driving roller, 29 ... Driven roller, 30 ... Intermediate transfer belt cleaning device, 31 ... Fixing device, 32 ... Paper transport device, 3 ... Paper feed tray, 34 ... Discharge tray, 35 ... Secondary transfer device, 35a ... Transfer roller, 36 ... Pickup roller, 37 ... Registration rollers, 38a-38d ... Conveyance rollers, 39 ... Pre-registration rollers, 40 ... Discharge Roller, 41 ... fixing belt, 42 ... pressure roller, 43 ... fixing roller, 44 ... heating roller, 51 ... contact portion, 60 ... control unit, 200 ... wrinkle suppression unit, 201 ... time measuring unit, 202 ... temperature sensor , 203 ... storage section, 204 ... rotation detection section, 205 ... heater control section, 206 ... rotation control section, A ... document reading device, B ... apparatus main body, N ... nip area, S ... paper transport path, Sr ... reverse path

Claims (8)

A fixing device for fixing toner on paper by heat of an endless fixing belt heated by a heater while rotating;
A rotation detection unit that detects rotation of the fixing belt during operation adjustment of the fixing device;
A heater control unit that turns on the heater when rotation of the fixing belt is detected by the rotation detection unit;
A fixing device comprising:   When rotation of the fixing belt is not detected by the rotation detection unit during operation adjustment, the fixing device is restarted. When the rotation detection unit detects rotation of the fixing belt, the heater control unit The fixing device according to claim 1, wherein the heater is turned on.   The heater control unit further includes a temperature sensor for detecting a temperature in the fixing device, and the rotation detection unit detects the rotation of the fixing belt, and the temperature sensor causes the temperature increase to exceed a predetermined value. 3. The fixing device according to claim 1, wherein the heater is turned off in the event of a failure.   The fixing device according to claim 3, wherein the predetermined value is 70 ° C. 5.   And a rotation control unit that rotates the fixing belt by a predetermined angle when rotation of the fixing belt is not detected by the rotation detection unit for a predetermined time while the heater is turned on when the fixing device is on standby. The fixing device according to claim 1, wherein:   The fixing belt further includes a heating roller that supports the fixing belt from the inside of the fixing belt and heats the fixing belt from the inside by heat generated by the heater, and the predetermined angle includes the heating roller and the fixing belt. The fixing device according to claim 5, wherein the fixing device has an angle formed by two straight lines lowered from both ends of the contact portion toward the center of the heating roller.   An image forming apparatus comprising the fixing device according to claim 1. A fixing device for fixing toner on paper by heat of an endless fixing belt heated by a heater while rotating is a heater control method for controlling the heater,
A rotation detecting step for detecting rotation of the fixing belt during operation adjustment of the fixing device;
A heater control step of turning on the heater when rotation of the fixing belt is detected by the rotation detection step;
A heater control method comprising:

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