JP6221963B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus.

  The image forming apparatus described in Patent Document 1 includes an intermediate transfer belt. The intermediate transfer belt is stretched around the support rotating body and rotates in an extended state. The image forming apparatus controls the rotation speed using optical indexes provided on both edges of the intermediate transfer belt. By tilting the optical index in a direction perpendicular to the rotation direction of the support rotating body, the intermediate transfer belt is prevented from breaking with the optical index as a starting point.

JP 2010-276667 A

  However, Patent Document 1 does not disclose overheating due to the breaking of the intermediate transfer belt. Overheating can cause a reduction in the performance of the device. The image forming apparatus includes, for example, a fixing device. The fixing device includes a heating roller and a pressure roller. Since the belt of the heating roller contacts the pressure roller and releases heat, the heating roller is kept at a constant temperature without being overheated. However, when the belt of the heating roller is partially broken, the portion of contact with the pressure roller is reduced, so that the heat of the heating roller is hardly released. Therefore, the heating roller is overheated and the temperature rises. As a result, the performance of the fixing device may be degraded.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device and an image forming apparatus capable of suppressing overheating of a heating roller.

  According to the first aspect of the present invention, the fixing device includes a heating member, a pressure member, and a rotation detection unit. The heating member includes a belt that heats the sheet, and the pressing member pressurizes the sheet and rotates the belt. The rotation detection unit detects a shift in the rotation of the other end with respect to the rotation of the one end of the belt.

  According to a second aspect of the present invention, an image forming apparatus includes the fixing device according to the first aspect of the present invention and an image forming unit. The image forming unit forms an image on the sheet.

  According to the present invention, since it is possible to detect that the belt is torn, it is possible to stop the heat generation of the broken belt and to prevent the belt from being overheated.

1 is a schematic diagram illustrating a fixing device according to Embodiment 1 of the present invention. 1 is a cross-sectional view showing a fixing device according to Embodiment 1 of the present invention. FIG. 3 is a schematic diagram illustrating a rotation detection unit of the fixing device according to the first exemplary embodiment of the present invention. It is a schematic diagram which shows the outline of the image forming apparatus which concerns on Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated.

(Embodiment 1)
The fixing device 1 will be described with reference to FIGS. 1 and 2. FIG. 1 shows a fixing device 1. FIG. 2 is a cross-sectional view showing the fixing device 1. The fixing device 1 includes a heating roller 10 as a heating member, a rotation detection unit 20, a pressure roller 30 as a pressure member, a magnetic flux generation device 40, a current supply circuit 45, a control unit 60, and a display unit. 70. The fixing device 1 fixes unfixed toner formed on the sheet T to the sheet T by heating and pressurizing the sheet T.

  The heating roller 10 includes a belt 11 and a belt guide 12 that heat the sheet T. The belt 11 is endless. The belt 11 is made of nickel, plated with copper, and has heat resistance and rigidity. The belt guide 12 is made of stainless steel (SUS). Stainless steel is a rust-resistant alloy steel containing iron and chromium. The belt guide 12 holds the belt 11 in a circular shape. The surface of the belt guide 12 that faces the magnetic flux generator 40 via the belt 11 keeps the distance from the magnetic flux generator 40 to the belt 11 constant.

  The rotation detection unit 20 detects a shift in the rotation of the other end with respect to the rotation of the one end of the belt 11. The rotation detection unit 20 includes a first detection unit 21 and a second detection unit 22. The first detector 21 is close to one end of the belt 11. The first detector 21 detects the rotational speed of one end of the belt 11. The first detector 21 generates a first pulse signal having a pulse width corresponding to the rotational speed of one end of the belt 11. The second detector 22 is close to the other end of the belt 11. The second detector 22 detects the rotational speed of the other end of the belt 11. The second detection unit 22 generates a second pulse signal having a pulse width corresponding to the rotational speed of the other end of the belt 11.

  The pressure roller 30 pressurizes the sheet T. The pressure roller 30 is rotated by a driving source such as a motor. A nip is formed by the contact between the pressure roller 30 and the belt 11. The sheet T is heated and pressed by passing through the nip. The pressure roller 30 rotates the belt 11 by a frictional force generated between the pressure roller 30 and the belt 11.

  The magnetic flux generator 40 generates a magnetic flux for causing the belt 11 to generate heat. The magnetic flux generator 40 includes a coil 41, a bobbin 42, and a magnetic core 43. The magnetic flux generation device 40 extends along the width direction of the belt 11 and is disposed so as to face the belt 11 so as to surround substantially half of the outer peripheral surface of the belt 11. The coil 41 is formed by winding a litz wire in a loop shape a plurality of times along the width direction of the belt 11, and is attached to the bobbin 42. The current supply circuit 45 is connected to the magnetic flux generator 40 and supplies the magnetic flux generator 40 with a current for generating heat by the action of the magnetic flux generated by the magnetic flux generator 40. The coil 41 generates an alternating magnetic flux by the current supplied from the current supply circuit 45. The current is, for example, a high frequency current. The magnetic flux generated by the coil 41 passes through the magnetic core 43 and passes along the belt 11. An eddy current is generated in the belt 11 due to a change in the alternating strength of the magnetic flux passing through the belt 11. When an eddy current flows through the belt 11, Joule heat is generated by the electric resistance of the belt 11, and the belt 11 generates heat.

  The control unit 60 stops the heat generation of the belt 11 in accordance with the rotation deviation of the other end portion with respect to the rotation of the one end portion of the belt 11 detected by the rotation detection unit 20. Specifically, the control unit 60 stops the heat generation of the belt 11 by stopping the supply of current to the magnetic flux generator 40 of the current supply circuit 45. The controller 60 controls the pressure roller 30 with a drive signal for rotating the pressure roller 30.

  Since the belt 11 contacts the pressure roller 30 and releases heat, the heating roller 10 having the belt 11 is kept at a constant temperature without being overheated. However, when the belt 11 is partially broken, the contact portion between the belt 11 and the pressure roller 30 is reduced, so that the heat of the belt 11 is hardly released. Accordingly, the belt guide 12 of the heating roller 10 is overheated. Further, when the belt 11 is torn, there is a difference in heat released from the belt 11 between the torn portion and the unbroken portion. Therefore, the thermal expansion of the pressure roller 30 becomes nonuniform, and the circumferential length is different. As a result, a deviation occurs in the rotation of both ends of the pressure roller 30. Since the belt 11 rotates with the rotation of the pressure roller 30, when the rotation of both ends of the pressure roller 30 is deviated, the rotation of both ends of the belt 11 is also deviated.

  Therefore, it is possible to detect that the belt 11 has been torn by detecting the deviation of the rotation of the other end with respect to the rotation of the one end of the belt 11. As a result, heat generation of the torn belt 11 can be stopped, and overheating of the belt 11 can be prevented.

  The display unit 70 displays information. When the deviation of the rotation of the other end of the belt 11 from the rotation of the one end of the belt 11 exceeds a specified value, the control unit 60 causes the display unit 70 to display a message. The specified value and the message are arbitrarily set. The message is, for example, a sentence that prompts the user to give a warning.

  Next, the rotation detection unit 20 will be described in detail with reference to FIGS. 1 and 3. FIG. 3 shows the rotation detection unit 20. In FIG. 3, the tooth portions of the flange 13, the gear 23, the gear 51, and the gear 52 are omitted in order to prevent the drawing from becoming complicated. The configuration of the second detection unit 22 is the same as that of the first detection unit 21, and therefore the description thereof is omitted.

  The first detection unit 21 includes a flange 13, a light shielding unit 24, a photo interrupter 27, and a gear unit 50. The flange 13 is fixed to one end of the belt 11. The gear unit 50 includes a gear 51, a gear 52, and a shaft 53. The gear 51 and the gear 52 are fixed to the shaft 53. Accordingly, the gear 52 rotates as the gear 51 rotates.

  The light shielding unit 24 includes a gear 23, a shaft 26, and a light shielding plate 300. The light shielding plate 300 includes three light shielding pieces 25 arranged at equal intervals. The gear 23 and the three light shielding pieces 25 are fixed to the shaft 26. The photo interrupter 27 is provided with a light emitting unit and a light receiving unit. The three light shielding pieces 25 included in the first detection unit 21 and the three light shielding pieces 25 included in the second detection unit 22 are arranged so as to be detected by the photo interrupter 27 when they are in the same phase. The three light shielding pieces 25 of the first detection unit 21 and the three light shielding pieces 25 of the second detection unit 22 are arranged so as to be aligned.

  The flange 13 rotates in the direction indicated by the arrow A as the belt 11 rotates. The flange 13 and the gear 51 are connected. Accordingly, the gear 51 that meshes with the flange 13 rotates in the direction indicated by the arrow B as the flange 13 rotates, and the gear 52 rotates according to the rotation of the gear 51. Further, the gear 52 and the gear 23 are connected. Therefore, the gear 23 rotates in the direction indicated by the arrow C as the gear 52 rotates. Then, the three light shielding pieces 25 rotate according to the rotation of the gear 23 and intermittently block the light emitted from the light emitting portion of the photo interrupter 27. As a result, the photo interrupter 27 outputs a first pulse signal having a frequency corresponding to the rotation speed. Similarly, the photointerrupter 27 of the second detection unit 22 outputs a second pulse signal having a frequency corresponding to the rotation speed.

  The control unit 60 stops the heat generation of the belt 11 in response to detecting that the phase difference between the first pulse signal and the second pulse signal is equal to or greater than a predetermined value. The phase difference between the first pulse signal and the second pulse signal corresponds to the rotational deviation of the belt 11. The prescribed value of the phase difference is arbitrarily set.

  According to the present embodiment, the rotation detection unit 20 detects that the belt 11 covering the heating roller 10 has been torn by detecting a shift in rotation at both ends of the heating roller 10. Therefore, it is possible to stop the heat generation of the belt 11 in response to detecting the breakage of the belt 11, and the overheating of the heating roller 10 can be suppressed. As a result, overheating of the fixing device 1 caused by the belt 11 being broken can be prevented.

(Embodiment 2)
With reference to FIG. 4, an image forming apparatus 100 according to Embodiment 2 of the present invention will be described. FIG. 4 is a schematic cross-sectional view for explaining the outline of the image forming apparatus 100. The image forming apparatus 100 is, for example, a copying machine, a printer, a facsimile machine, or a multifunction machine. The multi-function peripheral includes, for example, at least two devices among a copier, a printer, and a facsimile.

  The image forming apparatus 100 includes a fixing device 1, a feeding unit 125, a transport unit 131, an image forming unit 140, a document transport unit 150, a discharge unit 160, an image reading unit 170, a display unit 180, and a control unit 190.

  The conveyance unit 131 conveys the sheet T to the image forming unit 140. The image forming unit 140 forms an image on the sheet T based on the image data. The image data is, for example, image data generated by the image reading unit 170. Specifically, the image forming unit 140 forms an image on the sheet T by the photosensitive drum 141, the charging unit 142, the exposure unit 143, the developing unit 144, and the transfer unit 145. The image forming unit 140 includes a cleaning unit 146 and a charge removal unit 147.

  The sheet T on which the image is formed is conveyed toward the fixing device 1. The fixing device 1 functions as the fixing device 1 according to the first embodiment. The fixing device 1 heats and pressurizes the sheet T, and fixes the image formed on the sheet T to the sheet T. The sheet T on which the image is fixed is conveyed toward the discharge unit 160. The discharge unit 160 discharges the sheet T.

  The image reading unit 170 reads an image of a document and generates image data. The feeding unit 125 feeds the sheets T stacked on the cassette 121 or the manual feed tray 123 to the transport unit 131.

  The display unit 180 displays information. The display unit 180 functions as the display unit 70 according to the first embodiment. The display unit 180 is a liquid crystal display, for example.

  The control unit 190 controls each element of the image forming apparatus 100. The control unit 190 functions as the control unit 60 according to the first embodiment.

  As described above with reference to FIG. 4, according to the second embodiment, the fixing device 1 functions as the fixing device 1 according to the first embodiment. Therefore, as in the first embodiment, it is possible to detect the breaking of the heating roller 10. In addition, the same effects as those of the first embodiment can be obtained.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof (for example, (1) to (4) shown below). In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. . Moreover, the shape, dimension, etc. of each component shown by said embodiment are an example, Comprising: It does not specifically limit, A various change is possible in the range which does not deviate substantially from the effect of this invention.

  (1) As described with reference to FIG. 2, the belt 11 generates heat by the magnetic flux generator 40 disposed outside the heating roller 10, but a heater is disposed inside the heating roller 10, and the heater is a belt. 11 may be heated.

  (2) As described with reference to FIG. 3, the light shielding plate 300 includes the three light shielding pieces 25, but the light shielding plate 300 may include a single light shielding piece 25 or a plurality of light shielding pieces other than three. The light shielding piece 25 may be included.

  (3) Although the photo interrupter 27 detects the rotation speed of the belt 11 using the light shielding piece 25, the rotation speed may be detected by detecting optical indexes provided at both ends of the belt 11. The optical index may be, for example, protrusions provided at both ends of the belt 11 or a plurality of openings formed at both ends formed at both ends of the belt 11.

  (4) As described with reference to FIG. 3, the light shielding plate 300 of the first detection unit 21 and the light shielding plate 300 of the second detection unit 22 are arranged so as to be in phase with each other. You may arrange | position so that it may have a phase difference. When the pair of light shielding plates 300 has a certain phase difference in advance, the phase difference at the start of rotation of the belt 11 is stored. The controller 60 detects a rotational deviation between both ends of the belt 11 based on the stored phase difference.

  The present invention can be used in the fields of fixing devices and image forming apparatuses.

DESCRIPTION OF SYMBOLS 1 Fixing apparatus 10 Heating roller 11 Belt 20 Rotation detection part 21 1st detection part 22 2nd detection part 30 Pressure roller 60 Control part 70 Display part 100 Image forming apparatus 150 Image formation part 180 Display part 190 Control part T Sheet

Claims (5)

A heating member having a belt for heating the sheet;
A pressure member that pressurizes the sheet and rotates the belt;
A rotation detecting unit that detects a shift in rotation of the other end part relative to the rotation of one end part of the belt ;
A control unit ,
The rotation detection unit includes a first detection unit and a second detection unit,
The first detection unit includes a flange, a light shielding unit including a light shielding piece, a first photo interrupter provided with a light emitting unit and a light receiving unit, and a plurality of gears.
The flange is fixed to one end of the belt and rotates with the rotation of the belt;
The plurality of gears rotate according to the rotation of the flange,
The light shielding piece rotates according to the plurality of gears, intermittently blocks light emitted from the light emitting unit of the first photo interrupter,
The first photo interrupter generates a first pulse signal;
The second detection unit includes a flange, a light shielding unit, a second photo interrupter provided with a light emitting unit and a light receiving unit, and a plurality of gears.
The flange is fixed to the other end of the belt and rotates with the rotation of the belt;
The plurality of gears rotate according to the rotation of the flange,
The light shielding piece rotates according to the plurality of gears, intermittently blocks light emitted from the light emitting unit of the second photo interrupter,
The second photo interrupter generates a second pulse signal;
The first pulse signal has a pulse width corresponding to the rotational speed of the one end of the belt,
The second pulse signal has a pulse width corresponding to the rotational speed of the other end of the belt;
The phase difference between the first pulse signal and the second pulse signal corresponds to the deviation,
The control unit is a fixing device that stops heat generation of the belt according to the shift .
Further comprising a table radical 113,
The fixing device according to claim 1 , wherein the control unit displays a message on the display unit when the deviation exceeds a specified value.
  The fixing device according to claim 1, wherein the light shielding piece of the first detection unit and the light shielding piece of the second detection unit are arranged so as to be in phase with each other.
  The light shielding piece of the first detection unit and the light shielding piece of the second detection unit are arranged so as to have a certain phase difference in advance,
  The fixing device according to claim 1, wherein the control unit detects the shift based on the phase difference.
A fixing device according to any one of claims 1 to 4,
An image forming apparatus comprising: an image forming unit that forms an image on the sheet.

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