JP4713945B2 - Fixing device - Google Patents

Description

The present invention relates to a fixing device disposed in an electrophotographic image forming apparatus such as a copying machine, a laser printer, or a facsimile machine. More specifically, each side plate constituting a part of a frame is provided with a support shaft. A pressure lever member that is rotatably supported to press the pressure roller means against the heat fixing roller, a lower heat insulating wall that covers the frame body from below, and a sheet to be conveyed between the heat fixing roller and the pressure roller means. The present invention relates to a fixing device including a lower guide wall that guides toward a nip portion.

A fixing device mounted on an image forming apparatus requires high temperature and pressure for a certain time in order to fix unfixed toner on a sheet. In particular, in recent years, color image forming apparatuses, which have been in increasing demand, require a higher amount of heat and pressure than monochrome machines in order to print multiple color toners. As a result, since the temperature of the sheet metal frame in the fixing device becomes high, it is necessary to prevent the user from touching the jam processing. For this reason, a metal frame including a pair of side plates, a bottom plate disposed between the lower regions of the side plates, and a ceiling plate (stay) disposed between the upper regions of the pair of side plates, A fixing device configured to be covered with a heat insulating wall (ceiling board and stay board) made of synthetic resin from above and below is already known (see Patent Document 1).

The fixing device is also a heat fixing roller, a pressure roller, and a pressure lever member for pressing the pressure roller against the heat fixing roller, and is rotatably supported on each side plate via a support shaft (pin). And a lower guide wall for guiding the conveyed paper toward the nip portion between the heat fixing roller and the pressure roller. The support shaft is fixed to each side plate. The lower guide wall is formed on the upper surface of a felt table that is detachably mounted between the side plates.
JP-A-01-274161

In the fixing device, each of the support shafts is fixed to a corresponding metal side plate, and the lower guide wall is formed by a member different from each of the support shafts. There is a variation in the positional accuracy with the wall, and the parallelism is not maintained, and there is a possibility that the sheet is conveyed obliquely to the nip portion between the heat fixing roller and the pressure roller. On the other hand, each function such as heat insulation, paper guide, and support of the pressure lever member is formed by separate members, so the number of parts is large, the configuration is complicated, and the assembly man-hour is increased. It becomes difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel fixing device that can sufficiently ensure the parallelism between each supporting shaft of a pressure lever member and a lower guide wall to prevent the skew of a sheet.
Another object of the present invention is to make it possible to sufficiently ensure the parallelism between each support shaft and the lower guide wall of the pressure lever member, to reduce the number of parts, and to be simple and compact in configuration. It is another object of the present invention to provide a novel fixing device that reduces the number of assembly steps and facilitates assembly work.

According to the present invention,
A pair of side plates, and a connecting means for connecting the side plates so as to face each other with a space therebetween, the connecting means including at least one lower connecting plate member for connecting the lower regions of the side plates. A frame body including; a heat fixing roller rotatably supported between the side plates; pressure roller means pressed against the heat fixing roller; pressure means for pressing the pressure roller means against the heat fixing roller. A pressure means including a pair of pressure lever members rotatably supported on each of the side plates via a pair of support shafts; a lower heat insulating wall that covers the lower connecting plate member from below; and a lower guide wall and guiding toward the nip portion between the heat fixing roller and the pressure roller means; in the fixing apparatus having a heat fixing a lower insulating wall covering the lower connecting plate member from below, the paper conveyed Guide toward the nip between the roller and pressure roller means A lower guide wall that, the pair of support shafts pair of pressure lever member is rotatably supported, consists of a single member integrally formed of a synthetic resin, a single member is freely separated to the frame A fixing device is provided that is mounted on the printer.
A locking groove extending from the upstream end toward the downstream is formed at the upstream end of each side plate in the sheet conveyance direction, and each of the side plates extends outward from the lower end to the side, and A locking flange extending in the conveying direction is formed, and a single member includes a main body portion extending in a flat plate shape in the axial direction of the heat fixing roller, and an axially outward portion from both axial ends of the main body portion. A lower heat insulating wall including a locked flange extending to the upstream end; an upstream end wall extending along the upstream end of the main body and upstanding from the upstream end; and from both axial ends of the upstream end wall, respectively An upright plate extending upward; the support shaft extending axially outward from the upper end of each of the upright plates; and the lower extending downward from the top of the upstream end wall between each of the upright plates A guide wall, and the single member is separated into the frame body between the frame body and the single member. The single member is locked to the frame by inserting and rotating each of the support shafts of the single member into the locking groove of the corresponding side plate. It is preferable that it is detachably mounted via the means.
In a state where the single member is mounted on the frame, each of the upright plates is positioned with a gap inside the corresponding side plate, and the lower guide wall and the upstream end wall are positioned between the side plates, The main body portion of the lower heat insulating wall is positioned so as to cover the lower connecting plate member from below in the lower region between the side plates, and each of the locked flanges of the lower heat insulating wall corresponds to the locking flange of the corresponding side plate. On the other hand, it is preferably positioned to polymerize from below.
The locking means is a space portion formed in an intermediate region in the transport direction and an upstream end extending in the axial direction of each locking flange of the side plate, and is spaced apart in the transport direction. A space portion having an upstream inner end and a downstream inner end extending in the axial direction; and formed in an intermediate region in the transport direction in each of the locked flanges of the main body portion of the lower heat insulating wall of a single member An elastic hook piece, and an upstream hook piece and a downstream hook piece respectively formed on the upstream side and the downstream side with respect to the elastic hook piece, and the elastic hook piece is a hooked flange. Extending from the downstream inner end of the space portion formed in the intermediate region to the upstream side of the upstream inner end of the space portion , and at least from the middle in the transport direction to the upstream side of each of the elastic locking pieces. The area is inclined upwards upstream and above the tip A latching step portion having an L-shaped cross section is formed on the side, and the upstream hook piece extends from the upstream end of each of the latched flanges of the main body portion and from the tip of the standing portion. The hook portion extending in the downstream direction, and the downstream hook piece extends upward from the downstream side of the base end of the elastic locked piece in each of the locked flanges of the main body portion, and the upright portion Each of the elastically-engaged pieces of the single member in the locking flange of the corresponding side plate in a state where the single member is mounted on the frame body. The locked stepped portion is inserted into the space portion from below and is elastically locked to the corner on the lower surface side at the upstream inner end of the space portion, and each locked portion of the downstream hook piece corresponds to each other. Projecting upward from the downstream inner end of the space in the locking flange of the side plate, The hooks of the upstream hook pieces protrude upward from the upstream ends of the locking flanges of the corresponding side plates and extend in the downstream direction along the upper surfaces of the screws. It is preferable that it extends in the downstream direction along the upper surface of the stop flange and is locked to the upper surface.
Each connecting means of the side plate includes a downstream lower connecting plate member disposed on the downstream side, and the locking means has a plurality of hooks formed on the downstream lower connecting plate member at intervals in the axial direction. Corresponding to each of the hook pieces, and a through hole formed in the main body portion of the heat insulating wall of the single member, each hook piece from the lower surface at the upstream end of the downstream lower connecting plate member Each of the through holes has an upstream inner end, and an upstream inner end extending in the axial direction. In a state where the single member is mounted on the frame body, each locking portion of the hook piece of the downstream side lower connecting plate member protrudes downward from the upstream inner end of the corresponding through hole in the single member, and Extending in the upstream direction along the lower surface of the main body portion of the lower heat insulating wall to lock the lower surface. Preferred.

Embodiments of a fixing device configured according to the present invention will be described below in detail with reference to the accompanying drawings.

1 to 3 and 7, the fixing device according to the present invention includes a sheet metal frame 2. The frame body 2 is formed of a metal plate, and a pair of side plates 4 and at least one lower connecting plate member for connecting the lower regions of the side plates 4. In the embodiment, two lower connecting plates. The upper lower connecting plate member 6 and the downstream lower connecting plate member 8, which are members, and the upper connecting plate member 10 that connects the upper regions of the side plates 4 are provided. The upstream side lower connecting plate member 6, the downstream side lower connecting plate member 8, and the upper connecting plate member 10 constitute connecting means for connecting the side plates 4 so as to face each other in parallel with a space therebetween. In the present specification, upstream and downstream are directions of paper conveyance (direction from right to left in FIG. 1 and from right to left in FIGS. 2 and 3). This means upstream and downstream in the “conveying direction”.

A locking groove 12 extending from the upstream end toward the downstream is formed at the upstream end of each of the side plates 4. Each of the locking grooves 12 having substantially the same configuration with each other (in other words, having substantially the same shape and size as each other) has an upper surface opposed in the vertical direction at a substantially constant interval. And a lower surface and a semicircular bottom surface. Each of the side plates 4 is formed with a locking flange 14 that extends from the lower end to the side outward at a right angle and horizontally and extends in the transport direction. Each of the locking flanges 14 having substantially the same configuration as each other has a rectangular shape that is long in the transport direction when seen from the plane.

A through hole 16 is formed in each central region of the side plate 4. Each of the through holes 16 has substantially the same configuration as each other and exists on a common axis. In each through hole 16 of the side plate 4, both end portions of the shaft 20 of the heat fixing roller 18 are rotatably supported via bearings 22 (only one of them is shown in FIGS. 1 and 4). Is shown). Each of the side plates 4 has a cut extending from a partial region in the circumferential direction on the outer peripheral surface of each of the through holes 16 outward in the radial direction and reaching the proximal end of the corresponding locking flange 14. A notch 24 is formed. Each of the cutouts 24 having substantially the same configuration with each other extends linearly obliquely downward from upstream to downstream with a certain width in the conveyance direction.

Each of the locking flanges 14 includes an upstream end 14 </ b> A and a downstream end that extend in parallel in the axial direction of the heat fixing roller 18 (hereinafter simply referred to as “axial direction”) with an interval in the conveyance direction. 14 </ b> B, an outer end 14 </ b> C extending in the transport direction along the outer edge in the axial direction, and a base end 14 </ b> D that is a connecting portion with the side plate 14. A flat rectangular space 26 (in other words, a through hole) is formed in the central region in the transport direction of each of the locking flanges 14. Each of the space portions 26 having substantially the same configuration as each other includes an upstream inner end 26 </ b> A and a downstream inner end 26 </ b> B extending in parallel with the axial direction at intervals in the transport direction, and the locking flange 14. And an outer inner end 26C extending in the transport direction along the outer edge in the axial direction. A virtual inner inner end extending in the transport direction along the base end in each of the space portions 26 is continued to the lower end of the corresponding notch 24. Accordingly, each of the notches 24 and each of the space portions 26 are continuously connected to each other at the proximal end of the locking flange 14.

The upstream-side lower connecting plate member 6 includes a bottom plate portion 6A that extends straight with a certain conveyance direction width, and a pair of side plate portions 6B and 6C that stand upright from both sides in the conveyance direction of the bottom plate portion 6A. The upstream side plate portion 6B extends over the entire length of the bottom plate portion 6A, and the downstream side plate portion 6 extends in a region excluding both end regions of the bottom plate portion 6A. Both end regions of the bottom plate portion 6 </ b> A are superposed on the lower surface of the locking flange 14 in each of the side plates 4 and fastened by screws 28. Both end portions of the upstream side plate portion 6B are supported by penetrating slits formed corresponding to the side plate 4 and extending in the vertical direction, and the downstream side plate portion 6 is provided between the side plates 4. Exists.

The downstream-side lower connecting plate member 8 includes a bottom plate portion 8A that extends straight with a certain conveyance direction width, and a side plate portion 8B that extends upward from the upstream side in the conveyance direction of the bottom plate portion 8A. The side plate portion 8B includes a lower end portion 8a standing upright from the bottom plate portion 8A, an intermediate portion 8b extending obliquely upward and downstream from the upper end of the lower end portion 8a, and an upper end portion 8c extending straight upward from the upper end of the intermediate portion 8b. Yes. Both end regions of the bottom plate portion 8 </ b> A are superposed on the lower surface of the locking flange 14 in each of the side plates 4 and fastened by screws 29. Both end portions of the upper end portion 8c of the side plate portion 8B are inserted into and supported by slits formed corresponding to the side plate 4 and extending in the vertical direction. The lower end portion 8a and the intermediate portion 8b of the side plate portion 8B exist between the side plates 4 respectively. A plurality (two in the embodiment) of hook pieces 30 are formed in the downstream lower connecting plate member 8 at intervals in the axial direction. Each of the hook pieces 30 includes a hanging portion 30A extending downward from the lower surface at the upstream end of the bottom plate portion 8A of the downstream side lower connecting plate member 8, and a locking portion 30B extending upstream from the tip of the hanging portion 30A. . Locking portions 32 (only one of them is shown in FIGS. 6 and 7) at both axial ends of the upper end portion 8c of the downstream side lower connecting plate member 8 and at the inner positions of the corresponding side plates 4. Is formed. Each of the locking portions 32 is formed from a channel-shaped groove.

The upper connecting plate member 10 includes a top plate portion 10A that extends straight with a certain conveyance direction width, a pair of side plate portions 10B and 10C that hang down from both sides in the conveyance direction of the top plate portion 10A, and a shaft of the top plate portion 10A. A pair of end plate portions 10D (FIGS. 4 and 5) and 10E (FIG. 2) hanging from both ends in the direction are provided. The end plate portions 10D and 10E are positioned to face the inner side surfaces of the corresponding side plates 4, and are fastened by screws 34 (FIG. 1). The side plate portions 10B and 10C are formed longer than the top plate portion 10A, and both end portions thereof are supported by penetrating slits extending in the vertical direction formed corresponding to the side plates 4, respectively. .

The fixing device also includes a pressure roller unit 36 that is pressed against the heat fixing roller 18, and a pressure unit 38 (FIG. 10) that presses the pressure roller unit 36 against the heat fixing roller 18. A pressurizing means 38 including a pressurizing lever member 42 rotatably supported via a support shaft 40; a lower heat insulating wall 44 that covers the upstream lower connecting plate member 6 and the downstream lower connecting plate member 8 from below; And a lower guide wall 46 for guiding the conveyed paper toward the nip portion between the heat fixing roller 18 and the pressure roller means 36. The lower heat insulating wall 44, the lower guide wall 46, and the support shaft 40 are composed of a single member 50 integrally formed of synthetic resin, and the single member 50 is detachably attached to the frame body 2.

This will be described more specifically. 2, 3, 8, and 9, a single member 50 integrally formed from an appropriate synthetic resin having elasticity, for example, glass-filled PET (polyethylene terephthalate), includes a main body 52 and a pair. The lower heat insulating wall 44 having the locked flange 54, the upstream end wall 58, a pair of upright plates 60, a pair of the support shafts 40, and the lower guide wall 46 are provided. The main body 52 of the lower heat insulation wall 44 extends in a flat plate shape in the axial direction and has a substantially rectangular planar shape. Each of the locked flanges 54 having substantially the same configuration with each other extends outward in the axial direction from both axial ends of the main body 52. The upstream end wall 58 has a channel-shaped cross-sectional shape that opens downward, and extends along the upstream end of the main body 52 and stands upright from the upstream end. Each of the upright plates 60 having substantially the same configuration as each other extends upward from both axial ends of the upstream end wall 58. Each of the support shafts 40 having substantially the same configuration as each other extends axially outward from the upper end portion of each of the upright plates 60 and is positioned on a common axis. The lower guide wall 46 extends obliquely from the top of the upstream end wall 58 between each of the upright plates 60 toward the upper downstream side.

Each of the locked flanges 54 is formed with an elastic locked piece 62, an upstream hook piece 64, and a downstream hook piece 66. Each of the elastically locked pieces 62 having substantially the same configuration as each other is formed in an intermediate region in the conveying direction of the corresponding locked flange 54 and in the downstream of the through hole 68 formed in the intermediate region. It extends from the end 68b in the upstream direction to the upstream inner end 68a of the through hole 68. At least the region from the middle in the conveying direction to the upstream side in each elastic locked piece 62 is inclined upward toward the upstream side, and a locked stepped portion 62a having an L-shaped cross section is formed on the upper surface side of the tip portion. Has been. Each distal end portion of the elastic locked piece 62 in which the locked stepped portion 62 a is formed protrudes upward from the upper surface of the corresponding locked flange 54. Each of the upstream hook pieces 64 having substantially the same configuration as each other is formed on the upstream side with respect to the corresponding elastic locked piece 62 and extends upward from the upstream end of the corresponding locked flange 54. It consists of an upright part 64a and a locked part 64b extending in the downstream direction from the tip of the upright part 64a. Each of the downstream hook pieces 66 having substantially the same configuration as each other includes an upright portion 66a extending upward from the downstream side of the base end of the corresponding elastic locked piece 62, and a downstream direction from the distal end of the upright portion 66a. It is comprised from the to-be-latched part 66b extended in this.

Two through holes 69 are formed in the main body 52 of the heat insulating wall 44 corresponding to each of the two hook pieces 30 (FIG. 7) formed in the downstream lower connecting plate member 8. Each of the through holes 69 having substantially the same configuration as each other has a rectangular planar shape and includes an upstream inner end 69a that extends in the axial direction.

The upstream end 14A and the space 26 of each of the locking flanges 14 in the frame 2 (FIG. 7) described above, and each of the hook pieces 30 of the downstream lower connecting plate member 8 are each a single member 50 (FIGS. 8 and 8). Each of the elastically engaged pieces 62, the upstream side hook pieces 64, and the downstream side hook pieces 66 of the locked flange 54 in FIG. 9) and each of the through holes 69 of the main body 52 of the heat insulating wall 44 are frame bodies. 2 and the single member 50, and constitutes a locking means for detachably locking the single member 50 to the frame 2.

1 to 3 and 6, each of the support shafts 40 of the single member 50 is inserted into the locking groove 12 of the corresponding side plate 4 and slightly rotated (in FIGS. The single member 50 is detachably mounted on the frame body 2 via the locking means.

In a state in which the single member 50 is mounted on the frame body 2, each of the upright plates 60 is positioned with a gap inside the corresponding side plate 4, and the lower guide wall 46 and the upstream end wall 58 are each of the side plates 4. (See also FIGS. 4 and 5 together with FIG. 1). The main body 52 of the lower heat insulating wall 44 is positioned so as to cover the upstream and downstream lower connecting plate members 6 and 8 from below in the lower region between the side plates 4 (FIG. 2). Each of the locked flanges 54 of the lower heat insulating wall 44 is positioned so as to overlap with the locking flange 14 of the corresponding side plate 4 from below. Each of the elastic locked pieces 62 of the single member 50 is inserted from below into the space 26 in the locking flange 14 of the corresponding side plate 4, and the locked stepped portion 62 a is located in the upstream of the space 26. The end 26A is elastically locked to a corner on the lower surface side (FIG. 3). Each locked portion 66 b of the downstream hook piece 66 protrudes upward from the downstream inner end 26 B of the space portion 26 in the locking flange 14 of the corresponding side plate 4 and is downstream along the upper surface of the locking flange 14. And is locked to the upper surface (FIGS. 1 and 3). Each locked portion 64 b of the upstream hook piece 64 protrudes upward from the upstream end 14 A of the locking flange 14 of the corresponding side plate 4 and extends in the downstream direction along the upper surface of the locking flange 14. Locked to the upper surface (FIGS. 1 and 3). Each locking portion 30B of the hook piece 30 of the downstream side lower connecting plate member 8 protrudes downward from the upstream inner end 69a of the corresponding through hole 69 in the single member 50, and the main body portion 52 of the lower heat insulating wall 44. It extends in the upstream direction along the lower surface of and locks the lower surface (FIGS. 3 and 6).

As shown in FIG. 2, the upper connecting plate member 10 is covered from above by an upper heat insulating member 70 that is detachably attached to the frame body 2. The left side of the fixing device in FIG. 2 is covered by a discharge roller unit 72 that is detachably attached to the frame 2. As shown in FIGS. 1 to 3, the shaft 20 of the heat fixing roller 18 has a cylindrical shape, and a halogen heater H (FIG. 3) serving as a heat source is axially disposed in the central region of the heat fixing roller 18. It is arranged to extend to. A cover member (not shown) is detachably mounted on the outer side of each side plate 4 of the fixing device, and both ends of the halogen heater H are supported by the cover member.

As apparent from the above description, according to the fixing device of the present invention, each of the lower heat insulating wall 44, the lower guide wall 46, and the support shaft 40 is composed of a single member 50 integrally formed of synthetic resin. The single member 50 is configured to be detachably attached to the frame body 2. As described above, each support shaft 40 and the lower guide wall 46 of the pressure lever member 42 to be described later are integrally formed, and therefore, between each of the support shafts 40 and the lower guide wall 46. Mutual parallelism can be sufficiently ensured with high accuracy without causing variations in the accuracy of the mutual positional relationship. As a result, it is possible to prevent a problem that the sheet is conveyed obliquely to the nip portion between the heat fixing roller 18 and the pressure roller means 36 (the skew of the sheet is prevented). According to the fixing device of the present invention, the number of components is small, the configuration is simple and compact, and the number of assembling steps is reduced to facilitate the assembling work. Each of the support shafts 40 of the single member 50 is inserted into the locking groove 12 of the corresponding side plate 4 and rotated so that the single member 50 is almost touched with the frame body 2 through the locking means. It can be attached in a separable manner. In particular, each of the elastically-engaged pieces 62 of the single member 50 is so-called snap-fitted to the corresponding engagement flange 14 of the side plate 4, thereby facilitating the ease of assembly work. The locking means disposed between the frame 2 and the single member 50 prevents relative movement in the transport direction and the vertical direction. Further, the relative movement in the axial direction is carried out by conveying the two locking holes (not shown) formed in the upstream side plate portion 6B of the upstream lower connecting plate member 6 and the upstream end wall 58 of the single member 50. This can be prevented by relative fitting with two pins 58a (only one is shown in FIG. 2) extending in the downstream direction from the downstream end surface.

Next, a pressure roller means 36 provided in the fixing device, and a pressure means 38 (FIG. 10) for pressing the pressure roller means 36 against the heat fixing roller 18, each having a support shaft on each side plate 4. An embodiment of the pressurizing means 38 including the pressurizing lever member 42 that is rotatably supported via 40 will be described.

Referring to FIGS. 10 to 13, the pressure roller means 36 includes two support rollers 108 and 110 that are arranged at intervals in the tangential direction of the heat fixing roller 18 and around which an endless belt 106 is wound. I have. The support rollers 108 and 110 are pressed against the heat fixing roller 18 via the belt 106. On the inner peripheral surfaces of both sides in the width direction of the belt 106, ribs 107 for preventing meandering are disposed so as to extend over the entire circumference. In an embodiment, each of the ribs 107 has a rectangular cross section. At both ends of each of the support rollers 108 and 110, an annular step formed by a difference in outer diameter is disposed so as to be located inside the corresponding rib 107 in the width direction.

Bearings 120 and 122 are disposed at both ends of the shafts 108S and 110S in the support rollers 108 and 110, respectively. Both ends of the shafts 108S and 110S in each of the support rollers 108 and 110 are supported by the bearing holder 124 via bearings 120 and 122, respectively. Each of the bearing holders 124 having substantially the same configuration as each other includes a support cylindrical portion 126 that fits and supports the bearing 120 of one support roller 108 and a bearing 122 of the other support roller 110, and the one support roller 108. It has the plate-shaped main body 130 in which the support long hole 128 which carries out fitting support so that a movement to the direction which approaches and leaves | separates is carried out in parallel is formed. The plate-like main body 130 is configured by superposing the plate member 132 and the resin member 134 in a detachable manner, and has a substantially constant thickness. The support cylindrical portion 126 extends from one side of the plate-like main body 130 by a predetermined length.

Between each of the bearings 120 and 122 at both ends of the shafts 108S and 110S in each of the support rollers 108 and 110, a pressure plate 140 that is a pressure member having substantially the same configuration is disposed. Each of the pressure plates 140 having a flat plate shape includes a pair of pressure inclined surfaces 142 that come into contact with the outer peripheral surfaces of the bearings 120 and 122. More specifically, the space portion S in which the pressure plate 140 is removably inserted between the support cylindrical portion 126 and the support elongated hole 128 in the plate-like main body 130 in each of the bearing holders 124. Thus, a space S is formed in one side surface extending in the direction in which the support cylindrical portion 126 and the support elongated hole 128 are arranged in parallel. The opening 136 on one side extends linearly along the one side with a certain width. The space S and the opening 136 of the plate-shaped main body 130 in each of the bearing holders 124 are formed between the plate member 132 and the resin member 134. The space S extends in a flat plate shape with the same gap as the width of the opening 136.

Each of the pressure plates 140 has a shape symmetrical in the width direction with respect to a center line (not shown) extending in the vertical direction when viewed from the plane, and has a pair of pressure inclined surfaces 142 and a rectangular shape. A tongue piece 144, a pair of step portions 146, and a pair of other end inclined surfaces 148 are provided. The pair of pressure inclined surfaces 142 are formed on both sides in the width direction and are inclined linearly toward the center line in one of the longitudinal directions. The tongue piece 144 extends from the central region between one end of each of the pressure inclined surfaces 142 to one side in the vertical direction. The pair of stepped portions 146 extend in the width direction between one end of each of the pressure inclined surfaces 142 and the base ends on both sides in the width direction of the tongue piece 144. The pair of other inclined surfaces 148 are linearly inclined from the other end of each of the pressure inclined surfaces 142 to the other in the vertical direction toward the center line. The angle at which the pair of other inclined surfaces 148 intersect at the center in the width direction is formed from a curved surface and defines the other end protrusion 149 in each of the pressure plates 140.

When the pressure plate 140 is inserted into the space S from the opening 136 on the one side surface of each of the bearing holders 124, the pair of pressure inclined surfaces 142 in each of the pressure plates 140 are respectively connected to the support cylindrical portion 126 and the support length. While being brought into contact with the outer peripheral surfaces of the bearings 120 and 122 supported by the holes 128, the other end protrusions 149 in each of the pressure plates 140 are positioned so as to protrude from the openings 136 on the one side surface of each of the bearing holders 124.

Each of the bearing holders 124 is disposed inside the corresponding side plate 4, and the outer peripheral surface of the support cylindrical portion 126 is slidably and rotatably fitted in the notch 24 (FIG. 1). Is supported inside the side plate 4. Thereby, the movement of the bearing 120 of the support roller 108 fitted and supported by each of the bearing holders 124 and the support cylindrical portion 126 is substantially restricted in the tangential direction of the heat fixing roller 18.

The pressurizing means 38 is disposed corresponding to each of the pressure plates 140 and presses each of the pressure plates 140 so as to be released in the axial direction of the heat fixing roller 18. When each of the pressure plates 140 is pressurized by the corresponding pressure means 38, each of the support rollers 108 and 110 is heated via the pair of pressure inclined surfaces 142 and the outer peripheral surfaces of the bearings 120 and 122. A pressure is applied in the axial direction of the fixing roller 18 so that a partial area in the circumferential direction of the belt 106 is brought into pressure contact with a partial area on the outer peripheral surface of the heat fixing roller 18 and the support rollers 108 and 110 are separated from each other. To apply tension to the belt 106.

More specifically, the side plate 4 is located radially outward with respect to the heat fixing roller 18, at each of the bearing holders 124 in the radially outward position (radially outward position with respect to the heat fixing roller 18). The downstream lower connecting plate member 8 described above is disposed between the two. The pressing means 38 includes a pair of pressing arm members 152, a pair of tension coil springs 154, and a pair of pressing lever members 42.

A pair of pressure arm members 152 having substantially the same configuration are arranged at the radially outer positions of the bearing holders 124 on the inner side of the side plates 4, respectively, and one end portion 152 </ b> A is on the downstream side. The lower connecting plate member 8 is rotatably locked and supported by the locking portion 32 (FIGS. 6 and 7). Each of the pressure arm members 152 is formed of an elongated sheet metal having a channel-shaped cross section, and the one end portion 152A and the other end portion 152B are each bent into an L shape. The pair of tension coil springs 154 have substantially the same configuration as each other, and one end portions thereof are locked to the other end portion 152 </ b> B of the pressurizing arm member 152. The pair of pressure lever members 42 having substantially the same configuration as each other is supported by the intermediate portions inside the side plates 4 (the gap between each of the side plates 4 and the upright plate 60 (FIG. 5)). One end of the hook-like shape is supported by the other end of the tension coil spring 154 so as to be rotatable through the shaft 40.

In a state where no external force is applied to each of the pressure lever members 42, one end of each of the pressure lever members 42 having a hook shape is positioned so as to extend substantially horizontally (two-dot chain line in FIG. 10). The position indicated by Each of the pressure arm members 152 extends substantially in the tangential direction of the heat fixing roller 18 in a state where the one end portion 152 </ b> A is locked and supported by the locking portion 32 of the downstream lower connecting plate member 8. Positioned. The other end 152B of each pressure arm member 152 is positioned below the one end 152A. The force to move downward of each of the bearing holders 124, more specifically, from the support rollers 108 and 110, the belt 106, each of the bearings 120 and 122, each of the bearing holders 124, and each of the pressure plates 140. The force to move downward in the unit is transmitted to each of the pressure lever members 42 via each of the pressure plate 140, the pressure arm member 152, and the tension coil spring 154. Although it is intended to rotate counterclockwise around the support shaft 40 in FIG. Therefore, the pressing force by the pressurizing means 38 does not act on the unit.

A rotational moment is applied to the other end of each of the pressure lever members 42 to cause each of the pressure lever members 42 to move in one direction around the support shaft 40 against the spring force of the tension coil spring 154 (in FIG. 10), each of the pressure arm members 152 rotates counterclockwise in FIG. 10 with the locking portion 32 of the downstream lower connecting plate member 8 as a fulcrum by the spring force of the tension coil spring 154. The other end protrusion 149 of the corresponding pressure plate 140 is pressed to press the pressure plate 140 in the axial direction of the heat fixing roller 18 (a state indicated by a solid line in FIG. 10). Each of the pressure plates 140 presses each of the support rollers 108 and 110 in the axial direction of the heat fixing roller 18 via the pair of pressure inclined surfaces 142 and the outer peripheral surfaces of the bearings 120 and 122, respectively. A part of the circumferential direction is pressed against a part of the outer peripheral surface of the heat fixing roller 18, and each of the support rollers 108 and 110 is pressed away from each other to apply tension to the belt 106. When the pair of pressure inclined surfaces 142 in each of the pressure plates 140 press the outer peripheral surfaces of the bearings 120 and 122 of the support rollers 108 and 110 and try to separate them in the tangential direction of the heat fixing roller 18, Since the movement of the bearing 120 of the support roller 108 fitted and supported by each of the bearing holders 124 and the support cylindrical portion 126 in the tangential direction of the heat fixing roller 18 is substantially restricted, the bearing of the support roller 110 is supported. Only each of 122 is moved along the support slot 128 in the tangential direction away from each of the bearings 120 of the support roller 108 to apply tension to the belt 106.

As described above, in the fixing device according to the present invention, the lower heat insulating wall 44, the lower guide wall 46, and each of the support shafts 40 that support the pressure lever member 42 are integrally formed of synthetic resin. Since the single member 50 is formed, the positional accuracy between each of the support shafts 40 and the lower guide wall 46 does not vary, and the parallelism between the support shafts 40 and the lower guide wall 46 is maintained with high accuracy. 18 and the pressure roller means 36 are not conveyed obliquely (in contrast, conventionally, each of the support shafts 40 is fixed to a side plate made of a metal plate, so that the coefficient of thermal expansion is Due to differences, there is a high possibility that the positional accuracy with respect to the lower guide wall 46 will vary. Therefore, the parallelism will be deviated, and the sheet can be conveyed obliquely to the nip portion between the heat fixing roller and the pressure roller. The high A).

In the above embodiment, the pressure roller means 36 includes two support rollers 108 and 110, an endless belt 106 wound around the support rollers 108 and 110, and the like. There are also other embodiments comprising rollers.

1 is a perspective view showing an embodiment of a fixing device configured according to the present invention, and is a perspective view showing a part thereof omitted. FIG. FIG. 2 is a schematic cross-sectional view of the fixing device shown in FIG. 1 cut in the sheet conveyance direction, and is a schematic cross-sectional view including some members omitted in FIG. 1. FIG. 2 is a schematic cross-sectional view mainly showing locking means between a single member and a frame in the fixing device shown in FIG. 1. FIG. 2 is a partial schematic view of the fixing device shown in FIG. 1, with the left end portion in FIG. In FIG. 4, it is a figure which abbreviate | omits and shows the heat fixing roller and its support mechanism. It is the perspective view which looked at the state by which the single member was mounted | worn with the frame from the lower surface side. It is the perspective view which looked at the frame from the lower surface side. It is a perspective view of a single member. It is the perspective view which looked at the single member shown in FIG. 8 from the lower surface side. FIG. 2 is a schematic configuration diagram illustrating a pressing unit provided in the fixing device illustrated in FIG. 1, and is a schematic configuration diagram viewed in an axial direction of a heat fixing roller. It is a perspective schematic diagram which decomposes | disassembles and shows a part of structural member shown in FIG. It is the figure which looked at the bearing holder shown in FIG. 11 in the arrow A direction in FIG. It is the figure which looked at the bearing holder shown in FIG. 12 in the arrow B direction in FIG.

Explanation of symbols

2: Frame body 4: Side plate 8: Downstream lower connecting plate member 12: Locking groove 18: Root fixing roller 36: Pressure roller means 38: Pressure means 40: Support shaft 42: Pressure lever member 44: Lower heat insulating wall 46: Lower guide wall 50: Single member

Claims (5)

A pair of side plates, and a connecting means for connecting the side plates so as to face each other with a space therebetween, the connecting means including at least one lower connecting plate member for connecting the lower regions of the side plates. A frame body including; a heat fixing roller rotatably supported between the side plates; pressure roller means pressed against the heat fixing roller; pressure means for pressing the pressure roller means against the heat fixing roller. A pressure means including a pair of pressure lever members rotatably supported on each of the side plates via a pair of support shafts; a lower heat insulating wall that covers the lower connecting plate member from below; A lower guide wall that guides the heat guide roller toward the nip portion between the heat fixing roller and the pressure roller means,
A lower heat insulating wall that covers the lower connecting plate member from below, a lower guide wall that guides the conveyed paper toward the nip portion between the heat fixing roller and the pressure roller means, and a pair of pressure lever members that can rotate. The pair of support shafts to be supported are composed of a single member integrally formed of a synthetic resin, and the single member is detachably attached to the frame body.
A fixing device. A locking groove extending from the upstream end toward the downstream is formed at the upstream end of each side plate in the sheet conveyance direction, and each of the side plates extends outward from the lower end to the side, and A locking flange extending in the conveying direction is formed,
The single member includes the lower heat insulating member including a main body portion extending in a flat plate shape in the axial direction of the heat fixing roller and a locked flange extending outward in the axial direction from both axial ends of the main body portion. An upstream end wall extending along the upstream end of the main body and upstanding from the upstream end; an upright plate extending upward from both axial ends of the upstream end wall; and an upper end of each of the upright plates The support shaft extending outward in the axial direction from each of the sections; and the lower guide wall extending downstream from the top of the upstream end wall between each of the upright plates;
Between the frame and the single member, a locking means for detachably locking the single member to the frame is disposed,
Each of the support shafts of the single member is inserted into the locking groove of the corresponding side plate and rotated so that the single member is detachably mounted on the frame body through the locking means. Item 4. The fixing device according to Item 1. In a state where the single member is mounted on the frame, each of the upright plates is positioned with a gap inside the corresponding side plate, and the lower guide wall and the upstream end wall are positioned between the side plates, The main body portion of the lower heat insulating wall is positioned so as to cover the lower connecting plate member from below in the lower region between the side plates, and each of the locked flanges of the lower heat insulating wall corresponds to the locking flange of the corresponding side plate. 3. The fixing device according to claim 2, wherein the fixing device is positioned so as to be polymerized from below. The locking means is a space portion formed in an intermediate region in the transport direction and an upstream end extending in the axial direction of each locking flange of the side plate, and is spaced apart in the transport direction. A space portion having an upstream inner end and a downstream inner end extending in the axial direction; and formed in an intermediate region in the transport direction in each of the locked flanges of the main body portion of the lower heat insulating wall of a single member An elastic hook piece, and an upstream hook piece and a downstream hook piece respectively formed on the upstream side and the downstream side with respect to the elastic hook piece, and the elastic hook piece is a hooked flange. Extending from the downstream inner end of the space portion formed in the intermediate region to the upstream side of the upstream inner end of the space portion , and at least from the middle in the transport direction to the upstream side of each of the elastic locking pieces. The area is inclined upwards upstream and above the tip A latching step portion having an L-shaped cross section is formed on the side, and the upstream hook piece extends from the upstream end of each of the latched flanges of the main body portion and from the tip of the standing portion. The hook portion extending in the downstream direction, and the downstream hook piece extends upward from the downstream side of the base end of the elastic locked piece in each of the locked flanges of the main body portion, and the upright portion Consisting of a locked part extending in the downstream direction from the tip of the part,
In a state where the single member is mounted on the frame, each of the elastic locked pieces of the single member is inserted from below into the space portion in the locking flange of the corresponding side plate, and the locked stepped portion is Each of the locked portions of the downstream hook pieces protrudes upward from the downstream inner end of the space portion in the locking flange of the corresponding side plate. And it extends in the downstream direction along the upper surface of the locking flange and is locked to the upper surface, and each locked portion of the upstream hook piece is upward from the upstream end of the locking flange of the corresponding side plate. The fixing device according to claim 2, wherein the fixing device protrudes and extends in a downstream direction along the upper surface of the locking flange and is locked to the upper surface. Each connecting means of the side plate includes a downstream lower connecting plate member disposed on the downstream side, and the locking means has a plurality of hooks formed on the downstream lower connecting plate member at intervals in the axial direction. Corresponding to each of the hook pieces, and a through hole formed in the main body portion of the heat insulating wall of the single member, each hook piece from the lower surface at the upstream end of the downstream lower connecting plate member Each of the through holes has an upstream inner end, and an upstream inner end extending in the axial direction. ,
In a state where the single member is mounted on the frame body, each locking portion of the hook piece of the downstream lower connecting plate member protrudes downward from the upstream inner end of the corresponding through hole in the single member, and The fixing device according to claim 4, wherein the fixing device extends in an upstream direction along a lower surface of the main body portion of the lower heat insulating wall and locks the lower surface.

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