JP2017062442A - Fixation device and image formation apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixation device which can accurately adjust a gap distance between a fixation belt and a belt guide member.SOLUTION: Another side end in a circumferential direction of a circular arc part of a belt guide member is connected with a planar mounting plate part 473 having a through hole 474. A fixation device includes an adjustment member 48 which connects the mounting plate part 473 of the belt guide member 47 and a fixation member and adjusts the swelling quantity of the circular arc part 471 of the belt guide member 47 to a heating unit side. The adjustment member 48 includes: a regulation plate part 482 which penetrates the through hole 474 and regulates the swelling quantity of the circular arc part 471 of the belt guide member 47 by contacting an edge on the fixation member side of the circumferential part of the through hole 474; and connection parts 481, 483 which are connected to one side end in the penetration direction with respect to the through hole 474 of the regulation plate part 482 and connect the regulation plate part 482 and the fixation member.SELECTED DRAWING: Figure 5A

Description

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

  In recent years, fixing devices that employ a “belt system” in which a fixing nip is formed using a fixing belt heated by a heating unit have become widespread (see, for example, Patent Document 1). A pressing member that contacts a part of the inner peripheral surface is provided on the radially inner side of the fixing belt. The pressure roller is disposed opposite to the pressing member with the fixing belt interposed therebetween. The pressure roller is pressed against the pressing member by the urging means with the fixing belt interposed therebetween. Thereby, a fixing nip is formed between the pressure roller and the fixing belt. The heating unit is provided on the side opposite to the fixing nip side with respect to the rotation axis of the fixing belt. The heating unit is disposed on the outer side in the radial direction of the fixing belt, and a gap of a predetermined distance is provided between the heating unit and the outer peripheral surface of the fixing belt. A guide member is provided on the inner side in the radial direction of the fixing belt so as to face the heating unit. The guide member is formed by bending and bending a metal plate. The guide member has an arcuate section having an arcuate cross section that protrudes toward the heating part when viewed from the rotation axis direction of the fixing belt, and plate-like attachment parts connected to both ends of the arcuate part in the circumferential direction. doing. The guide member is fixed to a fixing member provided on the inner side in the radial direction of the fixing belt by a bolt penetrating each attachment portion.

JP 2014-145830 A

  By the way, in the fixing device shown in Patent Document 1, it is necessary to accurately control the fixing temperature of the toner in the fixing nip. For this purpose, the distance between the fixing belt and the cap of the heating unit is set in advance when the fixing device is assembled. It is necessary to adjust to the set distance. Here, the position of the fixing belt in the vicinity of the heating portion is defined by the guide member. Therefore, if the assembly accuracy of the guide member with respect to the fixing member is poor at the time of assembling the fixing device, the gap distance between the fixing belt and the heating unit is deviated from a preset set distance. As a result, there is a problem that the fixing temperature cannot be controlled to the target temperature.

  The present invention has been made in view of this point, and an object of the present invention is to make it possible to accurately adjust the gap distance between the fixing belt and the heating unit when the fixing device is assembled.

  A fixing device according to one aspect of the present invention includes an endless fixing belt, a pressure roller that is in pressure contact with an outer peripheral surface of the fixing belt and forms a fixing nip with the fixing belt, and an outer periphery of the fixing belt. A heating portion disposed with a gap with respect to the surface, and an arcuate portion having an arcuate cross section that is disposed so as to face the heating portion on the radially inner side of the fixing belt and bulges toward the heating portion. A belt guide member that includes the belt guide member, and a fixing member that is provided radially inward of the belt guide member and to which both ends of the arcuate portion of the belt guide member are attached and fixed.

  The arcuate portion of the belt guide member has a spring characteristic in which the other end portion is biased from the radially inner side toward the radially outer side with the one side end portion in the circumferential direction as a fulcrum. A flat plate-shaped mounting plate portion having a through hole is connected to the other circumferential end of the arc-shaped portion of the belt guide member, and connects the mounting plate portion of the belt guide member and the fixing member. And an adjustment member for adjusting the bulging amount of the arcuate portion of the belt guide member toward the heating portion when the fixing device is assembled. The adjustment member penetrates the through hole and passes through the through hole. A regulating plate portion that regulates the bulge amount of the arc-shaped portion of the belt guide member by abutting with an edge portion on the fixing member side of the peripheral portion of the hole, and a through direction of the regulating plate portion with respect to the through hole Connected to one side end portion of the restriction plate portion and And a connecting portion for connecting the serial fixing member.

  An image forming apparatus according to another aspect of the present invention includes the fixing device.

  According to the present invention, the gap distance between the fixing belt and the belt guide member can be accurately adjusted when the fixing device is assembled.

FIG. 1 is an overall schematic diagram illustrating an image forming apparatus including a fixing device according to an embodiment. FIG. 2 is a schematic cross-sectional view showing the fixing device according to the embodiment, taken along a cross section perpendicular to the rotation axis of the fixing roller. FIG. 3 is a perspective view showing the fixing roller. FIG. 4 is a cutaway view of FIG. 3 taken along the line IV-IV. FIG. 5A is a cross-sectional view showing the belt guide member and the guide adjusting member, taken along a cross section perpendicular to the rotation axis of the fixing roller. It is an enlarged view of the VB part of FIG. 5A. FIG. 6 is a perspective view showing the guide adjusting member. FIG. 7 is an explanatory diagram for explaining an assembling procedure for assembling the guide adjusting member to the belt guide member, and is an arrow view seen from the VII direction in FIG. 5A. FIG. 8 is an explanatory diagram for explaining an assembly procedure for assembling the adjustment member to the belt guide member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

<Embodiment>
FIG. 1 shows a laser printer 1 (hereinafter simply referred to as a printer) in the present embodiment. The printer 1 includes an apparatus main body 3 having an image forming unit 2. A paper feed unit 4 is provided in the lower part of the apparatus main body 3, and a paper discharge unit 5 is formed on the upper surface of the apparatus main body 3. A plurality of transport roller pairs 7 to 9 that sandwich and transport the paper P are arranged in order from the upstream side to the downstream side in the paper transport path 6 from the paper feed unit 4 to the paper discharge unit 5. In the following description, the front side and the rear side respectively mean the front side and the rear side in the direction perpendicular to the paper surface in FIG. 1, and the left side and the right side mean the left side and the right side in the left-right direction in FIG.

  The paper feed unit 4 includes a paper feed cassette 10 in which sheet-like paper P is accommodated, and a pickup roller 11 for taking out the paper P in the paper feed cassette 10 and sending it out of the cassette. . The paper P sent out of the cassette from the paper feed cassette 10 is supplied to the image forming unit 2 via the transport roller pair 7.

  The image forming unit 2 includes a photosensitive drum 21, a charger 23, an exposure device 25, a developing device 27, and a transfer device 29. At the time of image formation, first, the peripheral surface of the photosensitive drum 21 is charged by the charger 23, and then the original image data (for example, the image data of the original image received from the external terminal) on the surface of the photosensitive drum 21 by the exposure device 25. ) Is applied. Thus, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 21. The electrostatic latent image formed on the surface of the photosensitive drum 21 is developed with toner charged by the developing device 27. Thus, a toner image is formed on the surface of the photosensitive drum 21. This toner image is applied to the paper P by the transfer bias applied to the transfer roller 29a when the paper P supplied from the paper supply unit 4 passes between the photosensitive drum 21 and the transfer roller 29a of the transfer device 29. Transcribed. The sheet P on which the toner image has been transferred is sent downstream by the transfer roller 29 a and the photosensitive drum 21 and supplied to the fixing device 40.

  The fixing device 40 is disposed above the image forming unit 2. The fixing device 40 includes a fixing belt 41 and a pressure roller 42 that are arranged to face each other. A heating unit 43 described later is provided on the left side of the fixing belt 41, and the fixing belt 41 is heated by the heating unit 43. The pressure roller 42 is pressed against the fixing belt 41 by a biasing member (not shown). Thus, a nip portion N for nipping and conveying the paper P is formed between the fixing belt 41 and the pressure roller 42. As the paper P passes through the nip portion N, the toner image on the paper P is heated and pressurized and fixed to the paper P. The sheet P on which the toner image is fixed is sent out downstream by the fixing belt 41 and the pressure roller 42. The paper P sent out from the fixing device 40 is separated from the fixing belt 41 by a separation plate 49 (see FIG. 2) so as not to be wound around the fixing belt 41, and then the plurality of conveying roller pairs 8 and 9 described above. The paper is discharged to the paper discharge unit 5.

  Next, details of the fixing device 40 will be described with reference to FIGS. The fixing device 40 includes the fixing belt 41, the pressure roller 42, and the heating unit 43 as described above.

  The fixing belt 41 is made of a flexible cylindrical member (endless member). The pressure roller 42 includes a cylindrical cored bar 421, an elastic layer 422 formed on the outer peripheral surface of the cored bar 421, and a release layer (not shown) formed on the outer peripheral surface of the elastic layer. The pressure roller 42 is rotationally driven by a drive motor (not shown). The outer circumferential surface of the pressure roller 42 is in contact with the outer circumferential surface of the fixing belt 41, and the pressure roller 42 is driven to rotate by a drive motor so that the fixing belt 41 rotates following the pressure roller 42. It has become.

  The heating unit 43 is provided on the opposite side (left side) of the fixing belt 41 from the nip N side, and includes a coil 431 and a magnetic core 432. The coil 431 is connected to a power supply unit (not shown) and is disposed with a predetermined gap distance with respect to the outer peripheral surface of the fixing belt 41. The coil 431 is formed by winding a litz wire in a loop shape a plurality of times along the axial direction of the fixing belt 41. The magnetic core 432 is made of ferrite with high magnetic permeability such as MnZn alloy, and is formed so as to cover the entire coil 431 from the outside. When the coil 431 is energized by the power supply unit, the magnetic flux generated from the coil 431 passes through the magnetic core 432 and then passes through the induction heating layer of the fixing belt 41. As a result, an eddy current is generated in the induction heat generation layer, so that Joule heat is generated and the fixing belt 41 generates heat. When the fixing belt 41 is heated by the heating unit 43 and the temperature of the nip portion N reaches the target temperature, the toner image on the paper P sandwiched by the nip portion N is melted and fixed on the paper P.

  On the radially inner side of the fixing belt 41, a stay (fixing member) 44, a pressing pad 45, a magnetic shielding member 46, a belt guide member 47, and a guide adjusting member 48 are provided. The stay 44 extends in the front-rear direction (in the direction of the rotation axis of the fixing belt 41) on the radially inner side of the fixing belt 41. The stay 44 is a columnar body having a substantially U-shaped cross section that opens to the left, and both ends of the stay 44 in the front-rear direction are fixed to an outer wall case (not shown) of the fixing device 40.

  The pressing pad 45 is fixed to the right side surface (the surface on the nip portion N side) of the stay 44. The pressing pad 45 extends over substantially the entire front-rear direction on the right side surface of the stay 44. The pressing pad 45 is in contact with the inner peripheral surface of the fixing belt 41 and presses the fixing belt 41 toward the pressure roller 42. When the fixing belt 41 rotates, the inner peripheral surface of the fixing belt 41 slides with respect to the pressing pad 45.

  The magnetic shielding member 46 is formed of a bent plate having a substantially U-shaped cross section that opens to the right. The magnetic shielding member 46 extends in the front-rear direction and is disposed so as to cover the left side (the heating unit 43 side) of the stay 44. The magnetic shielding member 46 is fixed to the stay 44 via an attachment member (not shown). The magnetic shielding member 46 prevents the magnetism from the coil of the heating unit 43 from penetrating the stay 44.

  The belt guide member 47 is disposed on the outer side in the radial direction than the magnetic shielding member 46, and guides the fixing belt 41 from the inner side in the radial direction by contacting the inner peripheral surface of the fixing belt 41.

  As shown in FIG. 5A, the belt guide member 47 has an arcuate plate portion 471 and two attachment plate portions 472 and 473. The arcuate plate portion 471 is formed in a cross-sectional arc shape in which the central portion in the circumferential direction is convex toward the heating portion 43 when viewed from the front-rear direction (the rotation axis direction of the fixing belt 41). The arcuate plate portion 471 extends over substantially the entire front-rear direction (rotational axis direction) on the radially inner side of the fixing belt 41. An attachment plate portion 472 having an L-shaped cross section is connected to one end portion (lower end portion) in the circumferential direction of the arc-shaped plate portion 471.

The mounting plate portion 472 includes a vertical plate portion that extends downward from one circumferential end of the arc-shaped plate portion 471 and a horizontal plate portion that extends to the right from the lower end portion of the vertical plate portion. The horizontal flat plate portion is fixed to the lower surface of the stay 44 by a bolt 50 (see FIG. 4). The arcuate plate portion 471 has a spring characteristic in which the other end portion is biased from the radially inner side toward the radially outer side (in the direction of the thick arrow in FIG. 5A) with the one side end portion in the circumferential direction as a fulcrum. doing.

  A flat mounting plate portion 473 is connected to the other end portion (upper end portion) in the circumferential direction of the arc-shaped plate portion 471. The mounting plate portion 473 is a vertical plate extending downward from the other end portion (upper end portion) in the circumferential direction of the arcuate plate portion 471. A through-hole 474 that penetrates in the left-right direction (thickness direction) is formed in the mounting plate portion 473. A guide adjusting member 48 is engaged with the through hole 474, and the belt guide member 47 is fixed to the upper side surface of the stay 44 via the guide adjusting member 48 with a bolt 51 (see FIG. 4).

  The guide adjustment member 48 connects the mounting plate portion 473 of the belt guide member 47 and the stay 44, and the amount of bulging of the arcuate plate portion 471 of the belt guide member 47 toward the heating portion 43 when the fixing device 40 is assembled. It has a function to adjust P. As shown in FIG. 6, the guide adjustment member 48 includes a fixed plate portion 481, a regulating plate portion 482, a vertical plate portion 483, and a retaining piece 484. The fixed plate portion 481 has a plate shape extending horizontally in the front-rear direction, and is fixed to the upper side surface of the stay 44 with a bolt 51. The fixed plate portion 481 is formed with three bolt insertion holes 481a to 481c arranged in the front-rear direction at intervals, and the rearmost bolt insertion hole 481c has a long hole shape that is long in the front-rear direction. Thus, by providing the three bolt insertion holes 481a to 481c, the position adjustment of the guide adjustment member 48 in the front-rear direction can be easily performed.

  Referring to FIGS. 5A and 5B, the restricting plate portion 482 passes through the through hole 474 of the mounting plate portion 473 of the belt guide member 47, and the edge portion 474e (lower side of the stay 44 side in the through hole 474). The bulging amount P of the arcuate plate portion 471 of the belt guide member 47 toward the heating portion 43 is regulated by contacting the edge portion (see FIG. 5B). One side end portion (right end portion) in the penetration direction of the restriction plate portion 482 with respect to the through hole 474 is connected to the fixed plate portion 481 via the vertical plate portion 483. On the other hand, a retaining piece 484 protrudes downward from the other end (left end) in the penetrating direction with respect to the through hole 474 of the restriction plate 482. The retaining piece 484 is formed perpendicular to the restriction plate portion 482 and parallel to the vertical plate portion 483. Thus, the retaining piece 484 prevents the regulating plate portion 482 from coming out of the through hole 474.

  As shown in FIG. 7, the through hole 474 of the mounting plate portion 473 includes a first hole portion 474a and a second hole portion 474b. Both the first hole 474a and the second hole 474b are formed in a long hole shape extending in the front-rear direction. The second hole portion 474b is continuously connected to the rear end portion (one side end portion in the rotation axis direction) of the first hole portion 474a. The width of the second hole 474b (the dimension in the direction orthogonal to the front-rear direction) is larger than the width of the first hole 474a. The second hole 474b is formed in a size that allows the retaining piece 484 to pass through. On the other hand, the first hole 474a is formed in such a size that the retaining piece 484 cannot pass therethrough.

  When the belt guide member 47 is attached to the stay 44, the mounting plate 472 at one end in the circumferential direction of the belt guide member 47 (arc-shaped plate 471) is attached to the bolt 50 (see FIG. 4) on the lower surface of the stay 44. Fix with reference). In this state, the mounting plate portion 473 at the other circumferential end of the belt guide member 47 (arc-shaped plate portion 471) is fixed to the upper side surface of the stay 44 by the guide adjusting member. Specifically, as shown in FIG. 7, the restricting plate portion 482 of the guide adjusting member 48 is inserted into the through hole 474 of the mounting plate portion 473. At this time, the retaining piece 484 at the tip of the regulating plate 482 is inserted into the second hole 474b of the through hole 474 (see arrow D1 in FIG. 7), and then the entire guide adjusting member 48 is slid forward ( 7), the restricting plate portion 482 is passed through the first hole portion 474a. As a result, the guide adjusting member 48 is engaged with the belt guide member 47. In this state, the bolt 51 (in this embodiment, the central bolt insertion hole 481b) is inserted into any of the bolt insertion holes 481a to 481c of the fixing plate portion 481 to fix the fixing plate portion 481 to the upper side surface of the stay 44. . Thereby, the attachment of the belt guide member 47 to the stay 44 is completed.

  Thus, by fixing the other end of the belt guide member 47 in the circumferential direction to the stay 44 via the guide adjustment member 48, the amount P of the belt guide member 47 bulging toward the heating unit 43 can be easily increased. Can be adjusted. In other words, in a state where one side end of the arcuate plate portion 471 of the belt guide member 47 is fixed to the stay 44, the other end of the arcuate plate portion 471 of the belt guide member 47 moves radially outward. Although this is attempted (see the thick arrow in FIG. 5A), this movement is restricted by the restriction plate portion 482 coming into contact with the lower edge 474e (see FIG. 5B) of the through hole 474 in the attachment plate portion 473. As a result, the bulging amount P of the belt guide member 47 toward the heating unit 43 is restricted. Therefore, a plurality of guide adjusting members 48 having different thickness t of the fixed plate portion 481 are prepared in advance, or a plurality of guide adjusting members 48 having different distances A between the regulating plate portion 482 and the fixed plate portion 481 are prepared in advance. By doing so, the restriction position of the lower edge 474e of the through hole 474 can be adjusted, and the bulging amount P of the belt guide member 47 toward the heating part 43 can be easily adjusted. As a result, the gap distance G (see FIG. 5A) between the fixing belt 41 and the heating unit 43 guided by the belt guide member 47 can be accurately adjusted in the assembly stage of the fixing device 40. Therefore, it is possible to prevent the heating temperature of the fixing belt 41 by the heating unit 43 from deviating from the target temperature.

  Further, a retaining piece 484 is formed at the tip of the regulation plate portion 482. This reliably prevents the regulating plate portion 482 from coming out of the through hole 474 of the belt guide member 47, and the adjustment function of the bulging amount P of the belt guide member 47 by the guide adjustment member 48 is lost. Can be prevented.

The through hole 474 of the belt guide member 47 includes a first hole 474a through which the restriction plate 482 passes, and a second hole 474b continuously connected to the first hole 474a in the rotation axis direction of the fixing belt 41. The first hole 474a is formed in such a size that the retaining piece 484 cannot pass therethrough, while the second hole 474b is formed in such a size that the retaining piece 484 can pass therethrough. . According to this, as described above, the retaining piece 484 at the tip of the regulating plate 482 is inserted into the second hole 474b of the through hole 474 (see arrow D1 in FIG. 7), and then the entire guide adjusting member 48 is moved to the front side. It is possible to prevent the restricting plate portion 482 from coming out of the through hole 474 by a simple assembling operation of sliding to the right (arrow D2 in FIG. 7).
Here, the distance B between the retaining piece 484 and the vertical plate portion 483 is sufficiently larger than the plate thickness of the mounting plate portion 473 (see FIG. 5B). Therefore, the upper end portion of the arc-shaped portion 471 of the guide member 47 is not completely fixed and can be moved to the right side. According to this, even when the temperature of the fixing belt 41 is lowered due to a failure of the heating unit 43 or the like and the fixing belt 41 is thermally contracted, the upper end portion of the arcuate plate portion 471 is moved to the right along with the contraction. Accordingly, it is possible to prevent the contact pressure between the fixing belt 41 and the arc-shaped portion 471 from becoming excessive, and thus to prevent the fixing belt 41 from being damaged.

  As described above, the present invention is useful for a fixing device and an image forming apparatus including the fixing device.

41 Fixing belt
42 Pressure roller
43 Heating part
44 Stay (fixing member)
47 Belt guide member 471 Arc-shaped portion 472 Mounting plate portion 473 Mounting plate portion 474 Through hole 474a First hole 474b Second hole 474e Edge 48 Guide adjusting member
481 Fixed plate part (connecting part)
482 Regulating plate portion 483 Vertical plate portion (connecting portion)
484 retaining piece

Claims (3)

An endless fixing belt, a pressure roller that is in pressure contact with the outer peripheral surface of the fixing belt and forms a fixing nip with the fixing belt, and a gap with respect to the outer peripheral surface of the fixing belt are disposed. A heating unit, a belt guide member that is disposed to face the heating unit on the radially inner side of the fixing belt, and includes an arcuate portion having an arcuate cross section that bulges toward the heating unit; A fixing member provided on the inner side in the radial direction, to which both ends in the circumferential direction of the arc-shaped portion of the belt guide member are attached and fixed,
The arcuate portion of the belt guide member has a spring characteristic in which the other side end portion is biased from the radially inner side toward the radially outer side with the one side end portion in the circumferential direction as a fulcrum.
A flat mounting plate portion having a through hole is connected to the other end portion in the circumferential direction of the arc-shaped portion of the belt guide member,
An adjustment member for connecting the mounting plate portion of the belt guide member and the fixing member, and for adjusting the amount of bulging of the arc-shaped portion of the belt guide member toward the heating portion when the fixing device is assembled. Prepared,
The adjustment member passes through the through-hole and regulates the bulging amount of the arc-shaped portion of the belt guide member by contacting the edge of the through-hole at the fixed member side. And a connecting portion that is connected to one side end portion of the restricting plate portion in the penetrating direction with respect to the through hole and connects the restricting plate portion and the fixing member. The fixing device according to claim 1.
The through hole has a first hole portion through which the regulation plate portion passes, and a second hole portion continuously connected to the first hole portion in the rotation axis direction of the fixing belt,
The adjustment member further includes a retaining piece that is connected to one end portion in the penetrating direction of the restriction plate portion and prevents the restriction plate portion from coming out of the first hole portion,
The fixing device, wherein the first hole portion is formed in a size that prevents the retaining piece from passing therethrough, and the second hole portion is formed in a size that allows the retaining member to pass through. An image forming apparatus comprising the fixing device according to claim 1.

Images