JP4455116B2 - Belt shift control mechanism and fixing device - Google Patents

Description

The present invention may, for example, an electrophotographic apparatus effective belt deviation control mechanism applied to the fixing device of the belt type to be mounted on (printer copier, facsimile, etc.) the image forming apparatus or the like. The present invention also relates to a belt type fixing device.

  Conventionally, in an electrophotographic apparatus or the like, a heat-pressure type fixing apparatus that heats, pressurizes, melts, and fixes toner on a recording material is roughly classified. Alternatively, a heat source is arranged in both of them, and a roller type fixing device (roller fixing) that performs a fixing process by sandwiching and transporting a recording material in the pressure contact portion, and one is constituted by a roller and the other is constituted by a belt. There are two types of so-called belt type fixing devices (belt fixing).

  The roller fixing is basically composed of a roller pair of a fixing roller (heat roller) whose temperature is adjusted to a predetermined fixing temperature and a pressure roller pressed against the fixing roller, and the roller pair is rotated to rotate the roller. A recording material on which an unfixed toner image is formed is introduced into a fixing nip portion, which is a pair of pressure contact portions, and is nipped and conveyed, and the unfixed toner image is applied to the recording material by the heat of the fixing roller and the fixing nip portion pressure. It is to fix.

  Here, the amount of heat given to the recording material with the unfixed toner image is determined by the temperature of the fixing roller and the pressure roller, the time for the recording material to pass through the fixing nip portion, that is, the fixing nip width and the recording material traveling speed. Depends on. The fixing nip width refers to the length of the fixing nip portion in the recording material traveling direction.

  As a fixing device to be mounted on an electrophotographic apparatus or the like having a higher process speed, a fixing device having a wider fixing nip width is required because of the above heat quantity. In order to widen the fixing nip width in roller fixing, it is necessary to increase the diameter of the roller. If the diameter of the roller is increased, the heat capacity of the roller increases and the heat-up time (warm-up time) of the roller becomes longer. There's a problem.

  Therefore, as a fixing device configuration that can ensure a wide fixing nip width without increasing the diameter of the roller, for example, Patent Document 1 proposes a belt-type hot-pressure fixing device, so-called belt fixing.

  In belt fixing, a fixing nip portion is formed by press-contacting a heat-resistant / flexible endless belt stretched between a plurality of belt stretching members against a fixing roller which is a rotating body for heating, The recording material carrying the unfixed toner image is nipped and conveyed to the fixing nip portion, whereby the unfixed toner image is fixed to the recording material by heat and pressure with the heat of the fixing roller and the fixing nip portion pressure. In this belt-type fixing device, the fixing nip width can be easily set large by adjusting the width of the endless belt against the fixing roller of the endless belt. Further, since the fixing nip width can be secured without depending on the diameter of the fixing roller, the fixing roller can have a small diameter and a small heat capacity, and the start-up time can be shortened. Since the fixing nip width can be widened, the toner on the recording material can be melted more, and the fixing device is suitable for an image forming apparatus using a large amount of toner such as a color image forming apparatus.

  FIG. 16 is a schematic configuration diagram of an example of the belt-type fixing device 5. In the fixing device 5, reference numeral 510 denotes a fixing roller that is a rotatable rotating body that is rotatably arranged. The fixing roller 510 is rotationally driven in a clockwise direction indicated by an arrow A by a driving source (not shown), and is heated by a halogen heater 520 disposed therein. The surface temperature of the fixing roller 510 is detected by a thermistor 525 disposed on the surface of the fixing roller, and the power supply to the halogen heater 520 is controlled by a temperature control circuit (not shown) so that the detected temperature is maintained at a predetermined fixing temperature. Thus, the surface temperature of the fixing roller 510 is controlled to a predetermined fixing temperature.

  A belt unit 53 is disposed below the fixing roller 510. In this belt unit 53, 531 is an endless fixing belt. The fixing belt 531 is stretched by an entrance roller 532, a separation roller 533, and a steering roller 534 as a belt shift correction roller as a plurality of belt stretching members.

  The separation roller 533 is made of a metal such as SUS and is urged to move in the direction of the arrow SF and is in pressure contact with the fixing roller 510 via the fixing belt 531.

  The steering roller 534 is a swinging member, and one end side thereof is movable in the direction of arrow B, and has a function of correcting the deviation of the fixing belt 531.

  A pressure pad portion 540 is disposed between the entrance roller 532 and the separation roller 533. The pressure pad unit 540 includes a base 541 made of a metal such as SUS, a pressure pad 542 made of silicon rubber, and a sliding sheet 543 made of a PI film or the like disposed between the pressure pad 542 and the fixing belt 531. Then, it is urged to move in the direction of arrow PF and is in pressure contact with the fixing roller 510 via the fixing belt 531. A fixing nip portion W is formed by the fixing roller 510, the fixing belt 531, the pressure pad portion 540, and the separation roller 533 described above. The fixing belt 531 is rotated in the arrow C direction following the rotation of the fixing roller 510.

  An oil felt 536 is provided between the entrance roller 532 and the pressure pad portion 540. The oil felt 536 is impregnated with silicon oil, and the oil is applied to the inner surface of the fixing belt 531 to reduce the frictional force between the fixing belt 531 and the sliding sheet 543.

  When the fixing roller 510 is driven to rotate, the fixing belt 531 is also driven to rotate, and the fixing roller 510 is heated by the halogen heater 520 and adjusted to a predetermined fixing temperature. Then, a recording material (recording paper) P carrying an unfixed toner image t is introduced into the fixing nip W and is nipped and conveyed through the fixing nip W. In this nipping and conveying process, the unfixed toner image surface of the recording material P is brought into close contact with the surface of the fixing roller 510, and the toner image is heated by the heat of the fixing roller 510, and is fixed to the surface of the recording material P by heat and pressure. The recording material P is separated from the surface of the fixing roller 510 by the biting (entrance) of the separation roller 533 with respect to the elastic layer of the fixing roller 510 at the sheet exit portion of the fixing nip W, and is discharged and conveyed.

The fixing device 5 of such a belt type, since the take wide fixing nip width than roller fixing, can more melt the toner on the recording material, suitable for the image forming apparatus using a large amount of toner in the color image forming apparatus It is a configuration.

  In the above-described configuration, the fixing belt 531 rotates in the axial direction of the entrance roller 532, the separation roller 533, and the steering roller 534 (the longitudinal direction of the roller or the width direction of the belt that crosses the belt movement direction) as a stretching member of the belt. A phenomenon occurs in which one side or the other side moves more or less along the roller. This is due to the parallelism and torsion between the belt tension members, and there is a limit to increasing the accuracy of these. Stabilization) is difficult.

  Therefore, by rotating at least one belt stretching member of the plurality of belt stretching members as a swinging member and displacing the relative position with respect to other belt stretching members (changing parallelism and twist), the belt of the belt during rotation There is a belt shift control mechanism that controls shift movement in the axial direction of the tension member.

  In the belt-type fixing device 5 shown in FIG. 16, the steering roller 534 is used as a correction roller (swinging member) and controlled to swing, and the belt shifting direction is alternately changed and corrected to change the belt shifting movement to a predetermined level. It fits within the area width.

  In this method, as shown in Patent Document 2, when a belt deviation occurs by the belt position detecting means, one side of the correction roller 534 is moved in the B direction to alternately change and correct the belt deviation direction. Thus, there has been proposed a method in which the movement near the belt is accommodated within a predetermined movement area width.

  However, in this method, since the position of the correction roller changes only at one end side of the belt, the opening at one end side of the belt 531 as shown in FIG. In particular, in the belt-type fixing device, since the heat of 100 ° C. or more is applied to the fixing belt 531, the material is easily deformed, and the peripheral length is greatly different from that of the transfer belt of Patent Document 1, and thus the fixing shown in FIG. In the apparatus 5, when the steering roller 534 is moved, it is more remarkable that only one side of the fixing belt 531 spreads as shown in FIG.

  In order to control the deviation, as shown in FIG. 17, if the circumferences of the front and back of the fixing belt 531 are different, it becomes difficult to control the deviation by moving the steering roller 534.

As a countermeasure, a configuration has been proposed in which both ends of the steering roller 534 are moved in opposite directions so that both ends of the fixing belt 534 are spread equally as shown in FIG. As a driving method of this steering roller, as shown in Patent Document 3, a method has been proposed in which a fulcrum shaft is provided at the center of the roller holding member and a roller that controls the deviation of the belt is rotated around this fulcrum shaft.
JP 61-132972 A JP-A-06-009096 JP 05-001751 A

  However, the method of Patent Document 3 requires a roller holding member that holds both ends of the roller, and further has a fulcrum shaft at the center of the roller, so that the fulcrum shaft holding member is also fixed to a member that is arranged at both ends of the belt. It was necessary to Therefore, in order to arrange these parts, it has been a great obstacle to downsizing the apparatus.

The present invention has been proposed in view of the above, and a belt that controls the belt shift by changing the position of the front back (both ends of the front side end and the back end) of a roller disposed inside the belt. An object of the present invention is to reduce the size of a mechanism for moving the positions of the front and back of a roller in opposite directions with respect to the traveling direction of a belt in a belt-type fixing device including a shift control mechanism and a belt shift control mechanism.

The present invention is a belt shift control mechanism and a fixing device characterized by the following configurations.

(1) by a plurality of one belt-stretching roller belt mechanism having an endless belt that rotates being stretched between the belt-stretching roller to the swing member to displace the relative position with respect to the other of the belt-stretching roller In the belt shift control mechanism that controls the shift movement of the belt in the axial direction of the belt stretching roller during rotation,
A control shaft that is rotatably supported,
A first holding member , which is supported at one end of the control shaft so as to be rotatable with respect to the control shaft and holds one end of the swinging member, is formed with a first driven gear. A first holding member ;
A second holding member that is fixedly supported on the other end of the control shaft and holds the other end of the swing member;
A control arm fixedly supported adjacent to the first holding member on the control shaft, wherein the control arm is formed with a second driven gear ;
An idler gear meshing with the second driven gear of the control arm;
An input gear that meshes with the first driven gear and the idler gear of the first holding member and rotates the first holding member and the control arm in opposite directions by rotating ;
Has a displacement by said first and second holding member by the rotation of the input gear to rotate in the opposite directions about the axis of the control shaft, the ends opposite directions of the swing member A belt shift control mechanism.

(2) A rotatable fixing roller, a heating unit that heats the fixing roller, and an outer endless belt that is stretched and rotated between a plurality of belt stretching rollers, and presses the outer side of the endless belt against the fixing roller to fix the fixing nip. The belt mechanism that forms the belt and the belt tension roller axial direction of the belt during rotation by displacing the relative position of the belt mechanism relative to the other belt tension roller with one belt tension roller of the belt mechanism as a rocking member A fixing device for fixing a toner image by sandwiching and transporting a recording material carrying an unfixed toner image in the fixing nip portion.
The belt shift control mechanism is the belt shift control mechanism described in (1),
A pressure member that is provided inside the belt and presses the belt against the fixing roller;
A first pressure plate and a second pressure plate that pressurize the pressure member toward the fixing roller on one end side and the other end side of the control shaft in the belt shift control mechanism,
In order to selectively pressurize and release the belt from the fixing roller, the first pressure plate and the second pressure plate are rotated coaxially with the rotation center of the input gear in the belt shift control mechanism. A pivot shaft supported in a possible manner;
A drive motor that generates rotational drive force;
A relay gear that transmits the driving force of the drive motor to the input gear in the belt shift control mechanism;
Have
One end of a control shaft in the belt shift control mechanism is rotatably supported by the first pressure plate, and the other end is rotatably supported by the second pressure plate, and an input gear in the belt shift control mechanism. And the idler gear is rotatably supported by the first pressure plate.

  That is, the first holding member and the second holding member that swing and displace the one end side and the other end side of the swing member in opposite directions are connected only by the control shaft. The first holding member and the second holding member have a support shaft at the center, or a member for supporting the support shaft is not required, and the apparatus can be easily downsized.

[Example]

(1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration model diagram of an example of an image forming apparatus provided with a belt type fixing device to which a belt shift control mechanism according to the present invention is applied. FIG. 2 is an enlarged view of an image forming station portion of the image forming apparatus.

  The image forming apparatus of this example is a four-drum tandem type laser beam printer having a plurality of optical scanning units using an electrophotographic process. Since this printer itself belongs to the public domain, its description will be kept simple.

  In this printer, image information of a color document is color-separated and read by a photoelectric conversion element such as a CCD by a reader unit B disposed on the upper surface side of the printer body A. C is an automatic document feeder or document pressing plate for the document table crow B1 of the reader unit B. Laser light La, Lb, Lc, Ld modulated corresponding to each color separation read image information in the reader unit B is output from a laser scanning unit D having a plurality of optical scanning means.

  As shown in FIG. 2, the laser scanning section D is provided on the photosensitive drums 1a, 1b, 1c, and 1d of the four image forming stations Pa, Pb, Pc, and Pd that form images of magenta, cyan, yellow, and black. The toner images of the respective colors are formed on the photosensitive drums of the respective image forming stations by applying an electrophotographic process including a step of scanning exposure with the laser beams La, Lb, Lc, and Ld output from the above. Then, the magenta, cyan, yellow, and black toner images formed on the photosensitive drum of each image forming station are held on the transfer belt 31 of the transfer unit 3 and conveyed to a recording material P such as paper. It is configured to sequentially superimpose and transfer.

  Photosensitive drums 1a, 1b, 1c, and 1d are arranged in image forming stations Pa, Pb, Pc, and Pd that form images of magenta, cyan, yellow, and black, respectively. It is freely rotatable in the direction. Further, around the photosensitive drums 1a, 1b, 1c, and 1d, the chargers 12a, 12b, 12c, and 12d, the developing devices 2a, 2b, 2c, and 2d, and the cleaners 4a, 4b, 4c, and 4d are exposed to the above-described photosensitive. They are sequentially arranged along the rotation direction of the drum. A transfer section 3 is disposed below each photosensitive drum. The transfer unit 3 includes a transfer belt 31 serving as a recording material conveying unit common to each image forming station and transfer chargers 3a, 3b, 3c, and 3d. The transfer belt 31 is an endless belt, and is suspended and stretched between three rollers, that is, a driving roller 32 and turn rollers 33 and 34.

  E1 and E2 are first or second paper feed cassettes disposed in the printer main body A. The recording material P separated and fed by the recording material supply means from the paper feeding cassette E1 or E2 is supported on the transfer belt 31 and sequentially conveyed to the image forming stations Pa, Pb, Pc, Pd. Then, the toner images of the respective colors formed on the respective photosensitive drums are sequentially superimposed and transferred.

  When this transfer process is completed, the recording paper P is separated from the transfer belt 31 and conveyed to the fixing device 5. The toner image transferred to the recording paper P by the fixing device 5 is fixed on the recording paper P by heat and pressure and conveyed to the paper discharge processing device F as a full-color image formed product. In the paper discharge processing apparatus F, the recording paper P is discharged by the transport roller 61 on the paper discharge tray 62, and the paper discharge tray moves downward, so that a large number of sheets can be stacked. Further, the paper discharge processing apparatus F can also process a plurality of recording papers P to be stapled.

  In the double-sided copy mode, the recording paper P that has been copied on one side from the fixing device 5 is rerouted to the reversing / reconveying mechanism G side, reversed by the reversing / reconveying mechanism G, and re-fed to the transfer belt 31 As a result, a toner image is transferred and formed on the other side of the recording paper P, introduced again into the fixing device 5, and the double-sided copy is conveyed to the paper discharge processing device F.

(2) Fixing device 5
The fixing device 5 denotes a fixing device for a belt type according to the belt deviation control mechanism according to the present invention. FIG. 3 is a schematic cross-sectional view showing the schematic configuration. Basically, it has the same configuration as the above-described belt-type fixing device of FIG. 16, wherein 80 is a fixing roller (conveying roller), 100 is a fixing belt unit, 101 is an endless fixing belt, and 130 is an inlet roller (entrance roller). , 141 is a separation roller, 151 is a steering roller, and 160 is a fixing pad unit. The fixing roller 510, the belt unit 53, the fixing belt 531, the entrance roller 532, the separation roller 533, and the steering in the belt type fixing device of FIG. It corresponds to the roller 534 and the pressure pad portion 540. Fixing belt 101 of endless, as a plurality of belt tension roller, inlet roller 130, separating roller 141, it is allowed stretched between the three rollers of the steering roller 151. Fixing operation and control is Ru similar der the fixing device of a belt type in Fig. 16. That is, the outer side of the endless belt 101 that is stretched and rotated between a rotatable fixing roller 80, a heating means (520) that heats the fixing roller 80, and a plurality of belt stretching rollers 130, 141, and 151 is provided. The belt mechanism 100 that presses against the fixing roller 80 to form the fixing nip W, and the position of one belt stretching roller 151 of the belt mechanism as a rocking member is displaced relative to the other belt stretching rollers 130 and 141. And a belt shift control mechanism for controlling the shift of the belt 101 in the axial direction of the belt stretching roller during rotation, and the recording material P carrying the unfixed toner image t on the fixing nip W. Is a fixing device that fixes and fixes the toner image.

  A characteristic point is that the belt shift control mechanism in the fixing belt unit 100 is devised. Hereinafter, the belt deviation control mechanism will be described in detail.

  4 and 5 are perspective model views of the fixing belt unit 100 (the fixing belt is not shown). FIG. 4 is a perspective model view of the unit 100 viewed from the front side, and FIG. 5 is a perspective model view of the unit 100 viewed from the back side.

Fixing fixing pad portion of the belt unit 100 (pressing presses the belt with the fixing roller 80 provided on the inner side of the belt 101 material) 160 is fixed to the rear side plate 120 and the front side plate 110. Inlet rollers 130 are rotatably supported to the rear side plate 120 and the front side plate 110. In the separation roller unit 140, bearings 142 a and 142 b are attached to both end portions 141 a and 141 b of the separation roller 141. As shown in FIG. 4, the steering roller portion 150 is provided with a bearing 152 a at the front end portion 151 a of the steering roller 151, which is attached to the elongated hole 153 a of the front pressure arm 153. The steering roller 151 is a belt shift correction roller (swing member), and moves in the direction of the arrow b with respect to the long hole 153a of the front pressure arm 153. Further, the pre-pressurizing arm 153 pressurizes the steering roller in the direction of arrow c by a pressurizing spring 154a, thereby applying tension to the fixing belt 101 (FIG. 3).

  Similarly, on the rear plate 120 side, as shown in FIG. 5, a bearing 152 b is provided at the rear end portion 151 b of the steering roller 151 and attached to the elongated hole 155 a of the rear pressure arm 155. Thereafter, the steering roller 151 moves in the direction of the arrow b with respect to the elongated hole 155a of the pressure arm 155. Further, the rear pressure arm 155 presses the steering roller 151 in the direction of the arrow c by the pressure spring 154b, thereby applying tension to the fixing belt 101 (FIG. 3).

A steering control unit 200 includes a front steering roller support member (first holding member) 210 and a rear steering roller support member (second holding unit) 220. The front steering roller support member 210 and the rear steering are included. There is a control shaft 230 disposed at the rotation center of the roller support member 220. The front steering roller support member 210 is rotatably supported (rotatable ) at the front end (one end) of the control shaft 230, and the rear steering roller support member 220 is fixed to the rear end (other end) of the control shaft 230. (Fixed support) . Further, a steering detection flag 231 (FIG. 5) is provided on the control shaft 230, and the position of the control shaft 230 in the rotational direction is detected by the opposing detection sensor 232.

6 is a view as seen from the arrow X side in FIG. 4 to 6, when the fixing belt unit 100 is attached to the steering control unit 200 in the arrow Y direction, the receiving portion 151 c (FIG. 6) on the front side (one end side) of the steering roller 151 is connected to the front steering roller support member 210. It is mounted (held) in the U-groove 211, and the receiving portion 151 d on the rear side (the other end side) of the steering roller 151 is mounted (held) in the U-groove 221 of the rear steering roller support member 220.

FIG. 7 is a view of the front end side of the steering control unit 200 as viewed from above. A gear (first driven gear) 212 is formed on the front steering roller support member 210 and meshes with the input gear 241. The input gear 241 meshes with a control arm 243 formed with a gear (second driven gear) 243a via an idler gear 242. The control arm 243 is fixedly supported adjacent to the front steering roller support member 210 at the front end portion of the control shaft 230. Further, the idler gear 242 is not meshed with the gear 212 of the steering roller support member 210 due to a vertical positional relationship.

  In the above, the input gear 241 is a drive member. The gear 212 is a first drive transmission system that transmits the driving force of the input gear 241 as a drive member to the front steering roller support member 210 as a first holding member to rotate the support member 210. The idler gear 242 and the gear 243a transmit the driving force of the input gear 241 as a driving member to the rear steering roller support member 220 as a second holding member to rotate the support member 220. It is a system.

With the above configuration, when the input gear 241 rotates forward or backward, the front steering roller support member 210 rotates in the opposite direction to the input gear 241. Further, the rotation of the input gear 241 causes the control arm 243 to rotate in the same direction as the input gear 241 via the idler gear 242. The control arm 243 is fixed to the control shaft 230 and rotates the rear steering roller support member 220 in the same direction. That is, as the input gear 241 rotates, the front steering roller support member 210 and the rear steering roller support member 220 rotate in directions opposite to each other about the axis of the control shaft 230.

  Accordingly, the receiving portion 151c of the steering roller 151 mounted in the U groove 211 of the front steering roller support member 210 and the receiving portion 151d of the steering roller 151 mounted in the U groove 221 of the rear steering roller support member 220 are mutually connected. It will move in the opposite direction. That is, the front end side and the back end side of the steering roller 151 as a belt shift correction roller are moved in opposite directions to each other, so that the steering roller 151 can be compared with the inlet roller 130 and the separation roller 141 that are other belt stretching members. The relative position is displaced (parallelism and twist change). As a result, the belt shift direction is alternately changed, and the belt shift movement is accommodated within a predetermined movement area width.

  In the present embodiment, since the front steering roller support member 210 and the rear steering roller support member 220 are connected only by the control shaft 230, the center of the front steering roller support member 210 and the rear steering roller support member 220 as in the conventional example is particularly important. A part has a support shaft or a member for supporting the support shaft is not required, and the apparatus can be easily downsized.

  The gear train of the input gear 241 and the front steering roller support member 210, the input gear 241 and the idler gear 242 and the control arm 243 is the rotation of the front steering roller support member 210 and the control arm 243 with respect to the rotation of the input gear 241. As long as the direction is reversed, a similar effect can be obtained by arranging a plurality of gears or driving the timing belt.

FIG. 8 is a view showing a front pad pressure plate (first pressure plate) 331 and a rear pad pressure plate (second pressure plate) 332 that support the fixing belt unit 100. The fixing pad portion 160 is supported by a receiving portion 331a of the front pad pressure plate 331 and a receiving portion 332a (not shown; the same shape as the front pad pressure plate) of the rear pad pressure plate 332. Further, a fixing belt deviation detection unit 270 is attached to the rear pad pressure plate 332. Both ends of the control shaft 230 are rotatably held by the front pad pressure plate 331 and the rear pad pressure plate 332 by bearings.

FIG. 9 is a diagram showing the front pad pressure plate 331 side in a state where the fixing belt unit 100 is mounted on the front pad pressure plate 331 and the rear pad pressure plate 332, and the steering roller 151 is inserted into the U groove 211 of the front steering roller support member 210. A receiving portion 151c is attached. The control arm 243 is provided with a positioning hole 243c, and similar holes are also provided in the front steering roller support member 210 and the front pad pressure plate 331. A positioning hole 243c in the control arm 243, for the previous steering roller support members 210 holes in (not shown), before the holes (not shown) before the pad pressing plate 331 by matching the pad pressing plate 331 The phases of the front steering roller support member 210 and the control arm 243 can be matched. An input gear 241 and an idler gear 242 are also attached to the front pad pressure plate 331.

FIG. 10 is a diagram showing a pressure mechanism 300 that presses the fixing belt unit 100 against the fixing roller 80. The pressure mechanism 300 has a rotation shaft 301 attached to a fixing frame (not shown), and the cam 304 rotates about the cam shaft 303 to lift the roller 305 of the front pressure plate 311, thereby The pressure mechanism 300 is swung in the direction of the arrow U so that the fixing belt unit 100 is pressurized and attached to and detached from the fixing roller 80 (selectively pressurized and released) . The rear side (back side) of the fixing belt unit 100 has the same configuration.

  FIG. 11 is a view seen from the arrow K side in FIG. 10, and the pressure cam 304 lifts the front pressure plate 311. The pre-pressing plate 311 is provided with a pad pressurizing spring 312 and a separating pressurizing spring 313. The pad pressure spring 312 lifts the front pad pressure plate 331 in the direction of arrow F, and the separation pressure spring 313 lifts the front separation pressure plate 321 in the direction of arrow F. In this configuration, the rear pad pressure plate 332 side has a similar configuration.

  12A is a view of the front end side of the fixing device 5 as viewed from above, FIG. 12B is a view of the fixing device 5 as viewed from the front, and FIG. 12C is a cross-sectional view of FIG. A pressure bearing 143 is attached to the end 141 a of the separation roller 141. The pressure bearing 143 is in contact with the inclined surface 321 a of the pre-separation pressure plate 321. The rear side also has the same configuration, whereby the separation roller 141 is pressed against the fixing roller 80 in the direction of arrow J perpendicular to the inclined surface 321a of the front separation pressure plate 321. The front pad pressure plate 331 has a groove 331a, and the pad holder 161 is fitted to the groove 331a. This configuration is the same on the back side. As a result, the pad portion 160 presses the fixing roller 80 in the arrow K direction.

  The fixing pad 160 is pressed against the fixing roller 80 by the pressing mechanism 300 as described above. However, the front pad pressing plate 331 and the rear pad pressing plate 332 are independent, so that the fixing pad 160 is pressed. Can be pressurized properly at the front and back. Since the control shaft 230 is attached to the front pad pressure plate 331 and the rear pad pressure plate 332 by bearings and is not completely fixed, the positions of the front pad pressure plate 331 and the rear pad pressure plate 332 are not restricted.

FIG. 13 shows a state in which the fixing belt unit 100 is separated from the fixing roller 80. The pressurizing mechanism 300 moves the front pressurizing plate 311 in the V direction as the cam 304 rotates about the cam shaft 303. As a result, the fixing belt unit 100 is separated from the fixing roller 80. For example, when the fixing roller 80 and the fixing belt unit 100 are separated from each other, such as when a jam occurs in the fixing device 5, the jam processing can be easily performed.

FIG. 14 shows a state of the front pad pressure plate 331 in a state where the fixing belt unit 100 is separated from the fixing roller 80 (the same state as FIG. 9). Input gear 241 before the pad pressing plate 331, idler - gear 242, the control arm 243 is attached, before the pad pressing plate 331, before the control shaft 230 to the rear pad pressure plate 332 is held pressing plate 311, after Even if the pressure plate 312 rotates and the front pad pressure plate 331 and the rear pad pressure plate 332 rotate in the same manner, the steering control unit 200 rotates in the same manner, so that the fixing belt unit 100 is separated from the fixing roller 80. Similarly, the steering roller unit 150 can be controlled. Here, the rotation center of the input gear 241 is coaxial with the rotation shaft 301. As a result, the position of the input gear does not move even when the front pad pressure plate 311 rotates.

FIG. 15 is a view showing the steering drive unit 400, which is fixed to a fixing frame (not shown). An output gear 402 is attached to a steering drive motor ( forward / reverse rotation motor : drive motor that generates rotational drive force ) 401, and reduction gears 403a, 403b, 403c, and 403d drive the output gear 402 around shafts 403e and 403f. Is communicating. The relay gear 404a meshes with the reduction gear 403d and is fixed to the shaft 404c. Since the relay gear 404b is also fixed to the shaft 404c, when the relay gear 404a rotates, the relay gear 404b rotates in the same manner. The relay gear 404b meshes with the input gear 241 of the steering control unit 200. As a result, when the steering drive motor 401 rotates, the input gear 241 rotates and the front steering support member 210 and the rear steering support member 220 rotate in opposite directions.

Since the rotation shaft 301 at the rotation center of the input gear 241 is attached to a fixing frame (not shown) similarly to the steering drive unit 400, steering drive is performed even if the front pad pressure plate 331 is moved by the pressure mechanism 300. The drive of the part 400 can be transmitted.

  With the above-described configuration, the steering drive unit 400 is effective in realizing downsizing of the fixing device only by arranging the control shaft 230 on the front side and the rear side. Further, since the input gear 241 is arranged at the rotation center of the pressure mechanism 300, the drive system can be arranged on the fixed fixing frame.

In the belt-type fixing device of the present embodiment described above, the fixing roller 80 is driven to rotate, and the fixing belt 101 is driven to rotate accordingly. During the rotation process of the fixing belt 101 (when the belt 101 rotates) , the fixing belt 101 is rotated. Moves along the roller to one side or the other side of the belt stretching roller axis direction of the belt rollers 532, 533, and 534 (the longitudinal direction of the roller or the belt width direction that crosses the belt moving direction), and the deviation is allowed. When the belt position detection sensor (not shown) detects that the belt has been exceeded, the control unit (not shown) turns the fixing belt 101 back in the direction opposite to the side on which the steering belt 400 moves. The steering control motor 200 is controlled by rotating the steering drive motor 401 forward or backward to control the steering motor 200. To displace the error 151. When the belt shift position detection sensor no longer detects the belt due to the belt return movement, the driving of the steering drive motor 401 is stopped. By repeating this control operation, the belt shift direction can be changed and corrected alternately to keep the belt shift movement within a predetermined movement area width.

  In this embodiment, the belt type fixing device of the image forming apparatus has been described. However, the same mechanism is used in a transfer belt having a similar mechanism, and in a device using a belt other than the image forming apparatus, as in the present invention. The effect of can be obtained.

Schematic configuration model diagram of an example of an image forming apparatus provided with a belt type fixing device to which a belt shift control mechanism according to the present invention is applied. Enlarged view of the image forming station portion of the image forming apparatus Expanded cross-sectional model of the belt-type fixing device Perspective model view of the fixing belt unit (fixing belt not shown) viewed from the front Perspective model view of the fixing belt unit (fixing belt not shown) viewed from the back Front view with part omitted, viewed from arrow X side in FIG. View of the front end of the steering control unit as seen from above The figure which showed the front pad pressure board and back pad pressure board which support a fixing belt unit The front pad pressure plate side of the fixing belt unit mounted on the front pad pressure plate and the rear pad pressure plate The figure which shows the pressurization mechanism which pressurizes a fixing belt unit to a fixing roller The figure seen from the arrow K side of FIG. Explanatory drawing of pressurizing mechanism The figure which shows the state in which the fixing belt unit is separated from the fixing roller The figure which shows the state of the front pad pressurizing plate part in the state where the fixing belt unit is separated from the fixing roller The figure which shows a steering drive part Explanatory drawing of belt shift control of a conventional belt type fixing device The figure which showed the state where only one end side opening of the endless fixing belt became wide by belt shift control Diagram showing the state where the opening on both ends of the endless fixing belt is equally wide due to belt shift control

  80: fixing roller, 100: fixing belt unit, 150: steering roller unit, 200: steering driving unit, 300: pressure mechanism

Claims (2)

And a plurality of one belt-stretching roller belt mechanism having an endless belt that rotates being stretched between the belt-stretching roller to the swing member by displacing the relative position with respect to the other of the belt-stretching roller, In the belt offset control mechanism that controls the shift of the belt in the axial direction of the belt tension roller during rotation,
A control shaft that is rotatably supported,
A first holding member , which is supported at one end of the control shaft so as to be rotatable with respect to the control shaft and holds one end of the swinging member, is formed with a first driven gear. A first holding member ;
A second holding member that is fixedly supported on the other end of the control shaft and holds the other end of the swing member;
A control arm fixedly supported adjacent to the first holding member on the control shaft, wherein the control arm is formed with a second driven gear ;
An idler gear meshing with the second driven gear of the control arm;
An input gear that meshes with the first driven gear and the idler gear of the first holding member and rotates the first holding member and the control arm in opposite directions by rotating ;
Has a displacement by said first and second holding member by the rotation of the input gear to rotate in the opposite directions about the axis of the control shaft, the ends opposite directions of the swing member A belt shift control mechanism. A fixing nip is formed by pressing the outer side of a rotatable fixing roller, a heating means for heating the fixing roller, and an endless belt that is stretched between a plurality of belt stretching rollers to the fixing roller. The belt mechanism to be rotated and the belt tension roller in one of the belt mechanisms as a swing member to displace the relative position of the belt mechanism relative to the other belt tension roller. A fixing device that fixes a toner image by holding and conveying a recording material carrying an unfixed toner image in the fixing nip portion.
The belt shift control mechanism is the belt shift control mechanism according to claim 1,
A pressure member that is provided inside the belt and presses the belt against the fixing roller;
A first pressure plate and a second pressure plate that pressurize the pressure member toward the fixing roller on one end side and the other end side of the control shaft in the belt shift control mechanism,
In order to selectively pressurize and release the belt from the fixing roller, the first pressure plate and the second pressure plate are rotated coaxially with the rotation center of the input gear in the belt shift control mechanism. A pivot shaft supported in a possible manner;
A drive motor that generates rotational drive force;
A relay gear that transmits the driving force of the drive motor to the input gear in the belt shift control mechanism;
Have
One end of a control shaft in the belt shift control mechanism is rotatably supported by the first pressure plate, and the other end is rotatably supported by the second pressure plate, and an input gear in the belt shift control mechanism. And the idler gear is rotatably supported by the first pressure plate.

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