JP7255283B2 - Fixing device - Google Patents

Description

The present invention relates to a fixing device having an endless belt.

Conventionally, as a belt-type fixing device, there is known one that includes a pad that sandwiches an endless belt between itself and a heating roller, a holder that supports the pad, and a stay that supports the holder (see Patent Document 1). . Specifically, in this technique, the contact surface of the holder with the stay is a flat surface extending in the width direction of the endless belt from one end side to the other end side of the holder.

Japanese Patent Application Laid-Open No. 2010-230711

By the way, in order to make the nip pressure distribution in the width direction substantially uniform, the accuracy of the contact surface of the holder with the stay is important. However, in the prior art, since the contact surface of the holder with the stay is a plane elongated in the width direction, it is difficult to adjust the shape of the mold for molding the holder, and it is difficult to achieve dimensional accuracy. If the precision of the contact surface of the holder with the stay is poor, there arises a problem that the variation in the nip pressure distribution in the width direction increases.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the accuracy of the contact surface of the holder with the stay and to make the nip pressure distribution in the width direction substantially uniform.

In order to solve the above-described problems, a fixing device according to the present invention includes a heater, a rotating body heated by the heater, an endless belt, and a nip portion formed by sandwiching the endless belt between the rotating body. A nip forming member, a holder that holds the nip forming member, and a first stay that supports the holder are provided.
The holder includes a support wall positioned opposite to the rotating body with respect to the nip forming member and supporting the nip forming member; a plurality of ribs projecting from the support wall and contacting the first stay; have
The plurality of ribs extend in the moving direction of the endless belt in the nip portion and are spaced apart in the width direction of the endless belt.

According to this configuration, compared to a structure in which a flat surface formed in the holder and elongated in the width direction is brought into contact with the entire end of the stay, this configuration brings the plurality of ribs into contact with the first stay. The accuracy of the surface can be improved, and the nip pressure distribution in the width direction can be made substantially uniform. Moreover, since the support wall is more likely to deform along the first stay than when ribs that are elongated in the width direction are provided, the nip pressure distribution in the width direction can be made substantially uniform.

Further, the fixing device further includes an urging member that urges the first stay toward the rotating body, and the nip forming member and the rotating body sandwich the endless belt at an upstream nip portion. and a downstream nip forming member disposed downstream in the movement direction with respect to the upstream nip forming member, and forming a downstream nip portion with the endless belt sandwiched between the rotating body and the upstream nip forming member. and, in the moving direction, the distance from the first stay to the upstream end of the downstream nip forming member in the moving direction is equal to the distance from the first stay to the downstream end of the upstream nip forming member in the moving direction. may be smaller than the distance of

According to this, the first stay, which receives the biasing force from the biasing member, is arranged closer to the downstream nip forming member, so that the nip pressure at the downstream nip portion can be made appropriate.

In addition, the fixing device further includes a second stay arranged upstream of the first stay in the moving direction and supporting the holder, and the second stay is one of the plurality of ribs. It may have at least one protrusion that contacts the .

According to this, the support wall can be well supported by the first stay and the second stay.

Further, the distance from the protrusion to the center of the second stay in the width direction may be smaller than the distance from the protrusion to the end of the second stay in the width direction.

According to this, since the convex portion is arranged near the center of the second stay in the width direction, it is possible to suppress the deformation of the center portion of the support wall in the width direction toward the second stay.

The fixing device further includes a downstream guide that guides the inner peripheral surface of the endless belt on the downstream side of the nip forming member in the moving direction, and the first stay is for fixing the downstream guide. A hole may be provided, and the hole may be located at a different position from the rib in the width direction.

According to this, since there is no hole in the portion of the first stay where the force is transmitted from the rib, deformation of the first stay can be suppressed, and the nip pressure can be further stabilized.

Further, the holder has a holder body including the support wall and the ribs, and an engaging portion that engages with an end portion of the first stay in the width direction, and is different from the endless belt in the width direction. an engaging portion disposed at a position and extending from an end portion of the holder body in the width direction, the engaging portion comprising a pair of holding walls that sandwich the first stay in the movement direction; and a first connecting wall that connects the pair of holding walls.

According to this, the first stay is directly positioned in the holder by engaging the end of the first stay to which the load is input with the engaging portion of the holder. Positional accuracy in the direction of movement of the holder can be stabilized, and non-uniform nip pressure distribution can be suppressed.

Further, the first connecting wall may be positioned on a side opposite to the rotating body with respect to the widthwise end of the first stay, and may be in contact with the first stay.

According to this, the first stay can be sandwiched between the holder main body and the first connecting wall in the load input direction (the direction orthogonal to the width direction and the movement direction). Therefore, it is possible to further stabilize the positional accuracy of the holder with respect to the first stay. In addition, the holder and the first stay can be temporarily assembled satisfactorily, and assembly workability can be improved.

Further, the holder has a second connecting wall that connects the pair of holding walls, and the second connecting wall is opposite to the first connecting wall with respect to the widthwise end of the first stay. may be located on the side.

According to this, the rigidity of the engaging portion can be increased.

Further, the second connecting wall may be separated from the first stay.

For example, in a configuration in which the second connecting wall is in contact with the first stay, the distribution of the nip pressure in the width direction may change. can be suppressed.

Further, the holder main body has a side wall disposed between the support wall and the engaging portion in the width direction and extending in a direction intersecting the width direction, and the holder includes one holding wall and the holding wall. a first wall arranged parallel to one of the sandwiching walls and connected to the side wall; and a first wall arranged parallel to the side wall and connected to the side wall. and a second wall connecting the one holding wall.

According to this, since the clamping wall is reinforced by the reinforcing portion, the rigidity of the engaging portion can be increased.

Further, the holder main body has a first extending wall extending from the supporting wall to the side opposite to the nip forming member, and the first stay has a downstream surface positioned downstream in the moving direction. , the first extending wall may be in contact with the downstream surface.

According to this, since the first extending portion is in contact with the downstream surface of the first stay, it is possible to prevent the holder from tilting toward the downstream side.

Further, the holder main body has a second extending wall extending from the supporting wall in a direction opposite to the nip forming member, and the first stay has an upstream surface positioned upstream in the movement direction. , the second extending wall may be in contact with the upstream surface.

According to this, since the first stay can be sandwiched between the first extension wall and the second extension wall, deformation of the holder in the moving direction can be suppressed.

Further, the first extending wall and the second extending wall may be arranged at a position closer to the center of the holder body in the width direction than the engaging portion in the width direction.

According to this, it is possible to suppress the deformation of the center of the holder relative to the ends of the holder in the moving direction.

In addition, the fixing device further includes a movement restricting member that restricts movement of the first stay with respect to the holder in the width direction, and the first stay and the pair of holding walls are configured to restrict movement of the first stay. It may have a through hole through which the member is inserted.

According to this, the first stay can be positioned in the width direction with respect to the holder.

Further, the movement restricting member may be a metal wire rod.

According to the present invention, the accuracy of the contact surface of the holder with the stay can be improved, and the nip pressure distribution in the width direction can be made substantially uniform.

1 is a cross-sectional view showing a laser printer according to one embodiment of the present invention; FIG. 2 is a cross-sectional view showing a fixing device; FIG. FIG. 4 is an exploded perspective view showing each member arranged inside the endless belt; FIG. 4A is an enlarged exploded perspective view showing a nip forming member, a holder, and a spring, and FIG. FIG. 4 is a plan view of the holder to which the nip forming member and the spring are attached, as viewed from the rotating body side; It is the perspective view (a), top view (b), and side view (c) which show the structure around an engaging part. FIG. 4 is an exploded perspective view of the nip forming member, holder, stay, and downstream guide viewed from the side opposite to the rotating body; FIG. 4A is a perspective view of the holder body as seen from the opposite side of the rotating body, and FIG. 4B is a cross-sectional view showing the relationship between each extending wall and the first stay. FIG. 3A is a perspective view of the upstream guide as seen from the downstream side in the movement direction, and shows a state in which the upstream end of the sliding sheet is engaged with the upstream guide; is a diagram (b) showing a state in which the upstream end of the is sandwiched. Cross-sectional view (a) showing the structure around the connecting member of the stay, cross-sectional view (b) showing the structure of the part where the upstream guide, the first stay and the downstream guide are fastened together, and fixing the upstream guide and the second stay It is sectional drawing (c) which shows the structure of a part. FIG. 4 is a cross-sectional view of the pressurizing unit cut along a plane perpendicular to a predetermined direction, showing the positional relationship of each screw. 4 is a side view of the holder and the first stay viewed from the downstream side in the moving direction; FIG. FIG. 3 is an exploded perspective view showing a decomposed pressing mechanism and the like; FIG. 4 is a perspective view showing a state in which the holder, first stay, movement restricting member, bracket, etc. are assembled; It is the side view which looked at the pressing mechanism etc. from the width direction inner side.

An embodiment of the invention will be described in detail below with reference to the drawings as appropriate.
As shown in FIG. 1, the fixing device 8 according to the embodiment is used in an image forming apparatus 1 such as a laser printer. The image forming apparatus 1 includes a main housing 2 , a sheet feeding section 3 , an exposure device 4 , a developer image forming section 5 and a fixing device 8 .

The sheet supply unit 3 is provided in the lower part of the main body housing 2 and includes a sheet tray 31 in which sheets S such as paper are stored, and a sheet supply mechanism 32 . The sheet S in the sheet tray 31 is supplied to the developer image forming section 5 by the sheet supply mechanism 32 .

The exposure device 4 is arranged in the upper part of the main housing 2 and includes a light source device (not shown), a polygon mirror (not shown), a lens, a reflecting mirror, and the like. The exposure device 4 exposes the surface of the photoreceptor drum 61 by scanning the surface of the photoreceptor drum 61 at high speed with a light beam (see one-dot chain line) based on image data emitted from the light source device.

The developer image forming section 5 is arranged below the exposure device 4 . The developer image forming unit 5 is configured as a process cartridge and can be attached to and detached from the main housing 2 through an opening formed when a front cover 21 provided in the front portion of the main housing 2 is opened. The developer image forming section 5 includes a photosensitive drum 61, a charger 62, a transfer roller 63, a developing roller 64, a supply roller 65, and a developer containing section 66 containing dry toner developer. I have.

The developer image forming unit 5 uniformly charges the surface of the photosensitive drum 61 by the charger 62 . After that, the surface of the photosensitive drum 61 is exposed to light beams from the exposure device 4 to form an electrostatic latent image on the surface based on the image data. Further, the developer image forming section 5 supplies the developer in the developer containing section 66 to the developing roller 64 via the supply roller 65 .

Then, the developer image forming section 5 supplies the developer on the developing roller 64 to the electrostatic latent image formed on the photosensitive drum 61 . As a result, the electrostatic latent image is visualized and a developer image is formed on the photosensitive drum 61 . After that, the developer image forming section 5 transfers the developer image on the photosensitive drum 61 to the sheet S by conveying the sheet S supplied from the sheet feeding section 3 between the photosensitive drum 61 and the transfer roller 63 . to transcribe.

The fixing device 8 is arranged behind the developer image forming section 5 . Details of the fixing device 8 will be described later. The fixing device 8 thermally fixes the developer image onto the sheet S by passing the sheet S onto which the developer image has been transferred. The image forming apparatus 1 ejects the sheet S on which the developer image is thermally fixed onto the sheet ejection tray 22 outside the main body housing 2 by the transport rollers 23 and the ejection rollers 24 .

As shown in FIG. 2 , the fixing device 8 has a heating unit 81 and a pressure unit 82 . The pressing unit 82 is urged toward the heating unit 81 by a pressing mechanism 300 (see FIG. 15), which will be described later. In the following description, the direction in which the pressurizing unit 82 is urged toward the heating unit 81 is referred to as "predetermined direction". In this embodiment, the predetermined direction is a direction orthogonal to the width direction and the movement direction, which will be described later, and is the direction in which the heating unit 81 and the pressure unit 82 face each other.

The heating unit 81 has a heater 110 and a rotating body 120 . The pressure unit 82 also includes an endless belt 130 , a nip forming member N, a holder 140 , a stay 200 , a belt guide G, and a sliding sheet 150 . In the following description, the width direction of the endless belt 130 is simply referred to as "width direction". The width direction is the direction in which the rotation axis of the rotor 120 extends. The width direction is orthogonal to the predetermined direction.

The heater 110 is a halogen lamp that emits light and generates heat when energized, and heats the rotating body 120 by radiant heat. Heater 110 is arranged along the rotation axis of rotating body 120 so as to pass through the inside of rotating body 120 .

The rotating body 120 is a tubular roller elongated in the width direction and heated by the heater 110 . The rotating body 120 has a base pipe 121 made of metal or the like and an elastic layer 122 covering the outer peripheral surface of the base pipe 121 . The elastic layer 122 is made of rubber such as silicon rubber. In this embodiment, the rotating body 120 has an outer diameter at both ends in the width direction larger than the outer diameter at the center in the width direction, and has a concave shape in which the outer diameter gradually increases from the center in the width direction toward both ends. have. However, the shape of the rotating body is not limited to this. The rotating body may be, for example, a cylindrical roller having a uniform outer diameter in the width direction. Further, the rotating body may be a crown-shaped roller whose outer diameter gradually decreases from the center in the width direction toward both ends.

The rotating body 120 is rotatably supported by a side frame 83 (see FIG. 15), which will be described later, and is rotated counterclockwise in FIG. rotate around.

The endless belt 130 is a long tubular member and has flexibility. Although not shown, the endless belt 130 has a base material made of metal, resin, or the like, and a release layer covering the outer peripheral surface of the base material. The endless belt 130 rotates clockwise in FIG. 2 due to friction with the rotating body 120 or the sheet S when the rotating body 120 rotates. Lubricant such as grease is applied to the inner peripheral surface of the endless belt 130 . Inside the endless belt 130, a nip forming member N, a holder 140, a stay 200, a belt guide G and a sliding sheet 150 are arranged.

That is, the nip forming member N, the holder 140, the stay 200, the belt guide G and the sliding sheet 150 are covered with the endless belt 130. As shown in FIG. Here, the holder 140 and the stay 200 function as support members that support the nip forming member N. As shown in FIG. As shown in FIG. 3, the nip forming member N, the holder 140, the stay 200, the belt guide G, and the sliding sheet 150 are formed so that their widthwise dimensions are larger than the dimensions in each direction perpendicular to the widthwise direction. It is

As shown in FIGS. 2 and 3, the nip forming member N is a member that sandwiches the endless belt 130 with the rotating body 120 to form the nip portion NP. The nip forming member N includes an upstream nip forming member N1 and a downstream nip forming member N2.

The upstream nip forming member N1 has an upstream pad P1 and an upstream stationary plate B1.
The upstream pad P1 is a rectangular parallelepiped member. The upstream pad P1 is made of rubber such as silicone rubber. The upstream pad P1 sandwiches the endless belt 130 with the rotating body 120 to form an upstream nip portion NP1.

In the following description, the movement direction of the endless belt 130 at the upstream nip portion NP1 and the nip portion NP, which will be described in detail later, is simply referred to as the "movement direction." In the present embodiment, the direction of movement is the direction along the outer peripheral surface of the rotating body 120, but since this direction is the direction along the direction substantially perpendicular to the predetermined direction and the width direction, Suppose that it illustrates as a direction orthogonal to the width direction. Note that the moving direction is the same direction as the conveying direction of the sheet S at the nip portion NP.

The upstream pad P1 is fixed to the surface of the upstream stationary plate B1 on the rotor 120 side. The upstream pad P1 protrudes slightly upstream in the moving direction from the upstream end of the upstream stationary plate B1.

The upstream fixing plate B1 is made of a material harder than the upstream pad P1, such as metal. The upstream fixing plate B1 is longer in width than the upstream pad P1. Width direction end portions B11 and B12 of the upstream fixing plate B1 are located outside the respective end portions of the upstream pad P1 in the width direction.

The downstream nip forming member N2 is spaced apart downstream in the movement direction with respect to the upstream nip forming member N1. The downstream nip forming member N2 has a downstream pad P2 and a downstream stationary plate B2.

The downstream pad P2 is a rectangular parallelepiped member. The downstream pad P2 is made of rubber such as silicone rubber. The downstream pad P2 sandwiches the endless belt 130 with the rotating body 120 to form a downstream nip portion NP2. The downstream pad P2 is separated from the upstream pad P1 in the direction of movement.

Therefore, an intermediate nip portion NP3 exists between the upstream nip portion NP1 and the downstream nip portion NP2, where the pressure from the pressure unit 82 does not directly act. At the intermediate nip portion NP3, although the endless belt 130 is in contact with the rotating body 120, there is no member that sandwiches the endless belt 130 with the rotating body 120, so almost no pressure is applied. Therefore, the sheet S passes through the intermediate nip portion NP3 while being heated by the rotating body 120 and substantially without being pressed. In this embodiment, the region from the upstream end of the upstream nip portion NP1 to the downstream end of the downstream nip portion NP2, that is, the entire region where the outer peripheral surface of the endless belt 130 and the rotating body 120 contact is called the nip portion NP. That is, in the present embodiment, the nip portion NP includes a portion to which the pressing force from the upstream pad P1 and the downstream pad P2 is not applied.

The downstream pad P2 is fixed to the surface of the downstream fixed plate B2 on the rotor 120 side. The downstream pad P2 protrudes slightly downstream in the movement direction from the downstream end of the downstream stationary plate B2.

The downstream fixing plate B2 is made of a material harder than the downstream pad P2, such as metal. The downstream fixing plate B2 is longer than the downstream pad P2 in the width direction. Width direction end portions B21 and B22 of the downstream fixing plate B2 are located outside the respective end portions of the downstream pad P2 in the width direction.

Note that the hardness of the upstream pad P1 is greater than the hardness of the elastic layer 122 of the rotating body 120 . Further, the hardness of the downstream pad P2 is greater than the hardness of the upstream pad P1.

Here, hardness means durometer hardness defined in ISO7619-1. Durometer hardness is a value obtained from the depth of penetration of a specified indenter into a test piece under specified conditions. For example, when the durometer hardness of the elastic layer 122 is 5, the durometer hardness of the upstream pad P1 is preferably 6-10, and the durometer hardness of the downstream pad P2 is preferably 70-90.

The hardness of silicone rubber can be adjusted by changing the ratio of additives (silica-based filler or carbon-based filler) added during production. Specifically, increasing the ratio of the additive increases the hardness of the rubber. The hardness can also be reduced by adding silicone oil. Liquid injection molding or extrusion molding can be used as a method for producing the rubber. In general, low hardness rubber is suitable for liquid injection molding, and high hardness rubber is suitable for extrusion molding.

The holder 140 is a member that holds the nip forming member N. As shown in FIG. The holder 140 is made of heat-resistant resin or the like. The holder 140 has a holder body 141 and two engaging portions 142 and 143 .

The holder main body 141 is a part that holds the nip forming member N. As shown in FIG. Most of the holder body 141 is arranged within the range of the endless belt 130 in the width direction. More specifically, as shown in FIG. 5, the portion of the holder body 141 that is on the inner side in the width direction of each projection W10, W11 of the side wall W5, which will be described later, is arranged within the width BB of the endless belt 130 and the width of the side wall W5. A portion including each protrusion W10 and W11 is arranged outside the width BB of the endless belt 130 . A spring SP, which will be described later, is arranged within the width BB of the endless belt 130 . As shown in FIGS. 2 and 3, the holder main body 141 is supported by stays 200 (a first stay 210 and a second stay 220 which will be described later).

Each of the engaging portions 142 and 143 extends from each widthwise end of the holder body 141 . The engaging portions 142 and 143 are arranged at different positions from the endless belt 130 in the width direction. Specifically, as shown in FIGS. 5 and 12, each engaging portion 142, 143 is arranged outside the width BB of the endless belt . As shown in FIGS. 2 and 3, the engaging portions 142 and 143 are engaged with respective widthwise end portions of the first stay 210, which will be described later.

The stay 200 is a member positioned on the opposite side of the nip forming member N with respect to the holder 140 and supporting the holder 140 . The stay 200 has a first stay 210 and a second stay 220 .

The first stay 210 is a member that supports the holder body 141 of the holder 140 . The first stay 210 is made of metal or the like. The first stay 210 has a base portion 211 and a bent hemming portion HB.

The base portion 211 has a contact surface Ft that contacts the holder main body 141 of the holder 140 at one end on the holder 140 side. The contact surface Ft is a plane perpendicular to the predetermined direction. The base portion 211 is configured as a downstream wall disposed on the downstream side in the moving direction with respect to the bent hemming portion HB. The base portion 211 has a downstream surface Fa located on the downstream side in the moving direction and an upstream surface Fb located on the upstream side in the moving direction.

The hemmed bent portion HB is a portion bent by hemming. The hemming bent portion HB is bent from the other end of the base portion 211 and extends toward one end of the base portion 211 . The hemming bent portion HB has a bent portion 212 bent from the base portion 211 and an upstream wall 213 extending from the bent portion 212 toward the holder main body 141 side. The upstream wall 213 is arranged on the upstream side in the movement direction of the base portion 211 which is the downstream wall. The upstream wall 213 is arranged parallel to the base portion 211 . The upstream wall 213 faces the base portion 211 in the movement direction with a gap smaller than the plate thickness of the first stay 210 .

The hemming bent portion HB has a length in the width direction shorter than that of the base portion 211 . Each end of the base portion 211 in the width direction is located outside each end of the bent hemming portion HB in the width direction.

The base portion 211 has load input portions 211A, which receive force from a pressing mechanism 300 (see FIG. 15), which will be described later, at both ends in the width direction. The load input portion 211A is a recess opening on the side opposite to the nip forming member N in a predetermined direction, and is formed at the end portion of the base portion 211 on the side opposite to the nip forming member N in the predetermined direction.

A buffer member BF made of resin or the like is attached to the load input portion 211A. The buffer member BF is a member for suppressing rubbing between the metal base portion 211 and a metal pressing arm 310 (see FIG. 15) described later. The cushioning member BF includes a fitting portion BF1 fitted to the load input portion 211A, and a pair of leg portions BF2 arranged upstream and downstream in the movement direction with respect to the width direction end portions of the base portion 211. have.

The second stay 220 is a member that supports the holder body 141 of the holder 140 . The second stay 220 is made of metal or the like. The second stay 220 is arranged upstream of the first stay 210 in the movement direction. The second stay 220 includes a base portion 221 arranged parallel to the upstream wall 213 of the first stay 210 and an extension extending from the end of the base portion 221 opposite to the nip forming member N toward the first stay 210 . and an outlet 222 .

The width of the base portion 221 is longer than the extension portion 222 and the bent hemming portion HB of the first stay 210 . Each widthwise end of the base portion 221 is located outside each widthwise end of the extending portion 222 and the bent hemming portion HB. Each widthwise end of the base portion 211 of the first stay 210 and each widthwise end of the base portion 221 of the second stay 220 are connected by a connecting member CM. That is, the connecting member CM is connected to the base portion 211 at a position different from the bent hemming portion HB in the width direction.

As shown in FIG. 10( a ), the connecting member CM includes a crimping member SW that is crimped to the second stay 220 and a second screw SC<b>2 that fastens the crimping member SW to the first stay 210 . The crimping member SW includes a base portion SW1 sandwiched between the first stay 210 and the second stay 220, a first protrusion SW2 protruding from one end of the base portion SW1, and a second protrusion protruding from the other end of the base portion SW1. SW3.

The second stay 220 has a hole Hf through which the second projection SW3 passes. The second protrusion SW3 protrudes from the hole Hf to the upstream side in the moving direction, and the protruding tip is crimped. Thus, the second stay 220 is sandwiched between the crimped tip of the second projection SW3 and the other end of the base portion SW1.

The first stay 210 has a hole H11 into which the first protrusion SW2 is inserted. The first protrusion SW2 has a hole Ha at the tip thereof into which the second screw SC2 is screwed. The hole Ha is concave with a bottom. By screwing the second screw SC2 into the hole Ha, the first stay 210 is sandwiched between the head SC21 of the second screw SC2 and one end of the base portion SW1.

A hole H11 into which the first protrusion SW2 is inserted is arranged at a position corresponding to the two connecting members CM, as shown in FIG. One of the two holes H11 is a round hole, and the other hole H11 is an elongated hole elongated in the width direction.

As shown in FIGS. 2 and 3 , the belt guide G is a member that guides the inner peripheral surface 131 of the endless belt 130 . The belt guide G is made of heat-resistant resin or the like. The belt guide G has an upstream guide G1 and a downstream guide G2.

The upstream guide G1 has an upstream guide surface Fu that guides the inner peripheral surface 131 of the endless belt 130 on the upstream side of the nip forming member N in the rotational direction of the endless belt 130, more specifically, in the moving direction of the endless belt 130 in the nip portion NP. have. Specifically, the upstream guide surface Fu guides the inner peripheral surface 131 of the endless belt 130 via the sliding sheet 150 . The upstream guide G1 is separated from the upstream pad P1 in the direction of movement.

The downstream guide G2 has a downstream guide surface Fd that guides the endless belt 130 on the downstream side of the nip forming member N in the rotational direction of the endless belt 130, more specifically in the moving direction. Specifically, the downstream guide surface Fd guides the inner peripheral surface 131 of the endless belt 130 via the sliding sheet 150 . The downstream guide G2 is separated from the downstream pad P2 in the direction of movement. The downstream guide G2 is further away from the rotation center X1 of the rotor 120 than the downstream pad P2 in the predetermined direction.

The sliding sheet 150 is a rectangular sheet for reducing frictional resistance between the pads P1 and P2 and the endless belt 130. As shown in FIG. The sliding sheet 150 is sandwiched between the inner peripheral surface 131 of the endless belt 130 and the pads P1 and P2 at the nip portion NP. The sliding sheet 150 is made of an elastically deformable material. Although any material may be used for the sliding sheet 150, a resin sheet containing polyimide is used in this embodiment.

The sliding sheet 150 has a base portion 151 and a plurality (six) of hooks 152 . The base portion 151 is formed in a rectangular sheet shape. The base portion 151 has a sliding surface Fs (see FIG. 2) that slides on the inner peripheral surface 131 of the endless belt 130 . The base portion 151 has an upstream end portion 151A located at the upstream end in the rotation direction of the endless belt 130 and a downstream end portion 151B located at the downstream end.

An upstream end portion 151A of the base portion 151 is fixed to the upstream guide G1. The base portion 151 is arranged to cover the upstream guide surface Fu, the nip forming member N, and the downstream guide surface Fd.

The hook 152 is provided at the downstream end portion 151B of the base portion 151 . Hook 152 is part of sliding seat 150 . In other words, the hook 152 is sheet-like and elastically deformable. The hook 152 has a tip portion 152A and a neck portion 152B.

The distal end portion 152A has a shape in which the width (the length in the width direction) becomes narrower as the distance from the base portion 151 increases. The tip portion 152A protrudes from the neck portion 152B to one side and the other side in the width direction. The neck portion 152B connects the tip portion 152A and the base portion 151 . The width (length in the width direction) of the neck portion 152B is narrower than the maximum width of the tip portion 152A.

The downstream guide G2 has a hook engaging portion G21 with which the hook 152 engages. A plurality (six) of hook engaging portions G21 are provided corresponding to the plurality of hooks 152 . A plurality of hooks 152 and hook engaging portions G21 are arranged at intervals in the width direction.

The hook engaging portion G21 has an opening Hg with which the hook 152 engages. The tip width of the tip portion 152A of the hook 152 and the width of the neck portion 152B are smaller than the width of the opening Hg. Also, the maximum width of the tip portion 152A is larger than the width of the opening Hg.

As shown in FIG. 2 , the hook engaging portion G21 is arranged downstream of the downstream guide surface Fd in the rotational direction of the endless belt 130 and away from the endless belt 130 . The hook engaging portion G21 is arranged away from the base portion 211 of the first stay 210 on the downstream side in the moving direction.

The hook engaging portion G21 faces the base portion 211 of the first stay 210 in the moving direction. Specifically, the opening Hg of the hook engaging portion G21 faces the base portion 211 in the movement direction. The hook 152 of the slide sheet 150 engages with the opening Hg by being inserted into the opening Hg from the downstream side in the moving direction.

The distance between the hook engaging portion G21 and the base portion 211 in the movement direction is greater than the length of the tip portion 152A of the hook 152. As shown in FIG. Also, the length of the neck portion 152B of the hook 152 is greater than the thickness of the hook engaging portion G21.

As shown in FIG. 4A, the holder body 141 has a support wall W1, an upstream wall W2, a central wall W3, a downstream wall W4, and a pair of side walls W5. The holder main body 141 has a substantially symmetrical structure in the width direction. In the following description, one side (the right side in the drawing) of the structure of the end portion in the width direction of the holder main body 141 will be described as a representative, and description of the other side will be omitted.

The support wall W1 is a wall that supports the nip forming member N and is located on the opposite side of the nip forming member N from the rotating body 120 . The support wall W1 has an upstream support surface F1 that supports the upstream fixed plate B1 and a downstream support surface F2 that supports the downstream fixed plate B2. In a cross section perpendicular to the width direction, the upstream support surface F1 and the downstream support surface F2 are perpendicular to the predetermined direction. The upstream support surface F1 and the downstream support surface F2 are arranged at the same position in the predetermined direction. In a cross section orthogonal to the movement direction, the upstream support surface F1 and the downstream support surface F2 have a curved shape that is closer to the rotation center X1 of the rotating body 140 at the center in the width direction than at both ends in the width direction. . In other words, the upstream support surface F<b>1 and the downstream support surface F<b>2 have a central convex shape in which the center in the width direction protrudes toward the rotating body 120 . Also, the amounts of protrusion of the upstream support surface F1 and the downstream support surface F1 toward the rotating body 120 are substantially the same.

Mounting bosses W6 (see also FIG. 6A) are provided at both ends of the support wall W1 in the width direction. The mounting boss W6 is a portion to which a spring SP, which will be described later, is mounted. As shown in FIG. 4B, the mounting boss W6 is located farther from the rotating body 120 than the upstream fixing plate B1 and the downstream fixing plate B2 in a predetermined direction. As shown in FIGS. 4A and 5, the mounting bosses W6 protrude outward in the width direction from each width direction end of the support wall W1. The mounting boss W6 is located between one end B11 of the upstream fixing plate B1 and one end B21 of the downstream fixing plate B2 and between the other end B12 of the upstream fixing plate B1 and the other end of the downstream fixing plate B2 in the moving direction. It is located between B22.

The spring SP is a member that biases the upstream nip forming member N1 and the downstream nip forming member N2 away from each other. Specifically, the spring SP urges the upstream nip forming member N1 toward the upstream wall W2 and urges the downstream nip forming member N2 toward the downstream wall W4 in the movement direction. In addition, the spring SP urges the upstream nip forming member N1 toward the upstream support surface F1 of the support wall W1 and urges the downstream nip forming member N2 toward the downstream support surface F2 of the support wall W1 in a predetermined direction. I am gaining momentum.

The spring SP has a coil portion S1, a first arm portion S2, and a second arm portion S3. The coil portion S1 is a portion in which the wire is wound one turn or more. The mounting boss W6 supports the spring SP by entering the coil portion S1.

The first arm portion S2 is a portion that obliquely extends from one end of the coil portion S1 toward the moving direction upstream side and the rotor 120 side and contacts the one end portion B11 of the upstream fixed plate B1. Specifically, a recess B13 recessed toward the upstream side is formed at the downstream end of the one end B11 of the upstream fixing plate B1. The first arm portion S2 enters the recess B13 and contacts the bottom of the recess B13.

The second arm portion S3 is a portion that obliquely extends from the other end of the coil portion S1 toward the moving direction downstream side and the rotor 120 side and contacts the one end portion B21 of the downstream fixed plate B2. Specifically, the one end portion B21 of the downstream fixing plate B2 is formed to have a smaller width (length in the movement direction) than the central portion in the width direction of the downstream fixing plate B2. The upstream end of the one end portion B21 of the downstream fixing plate B2 is located downstream of the upstream end of the central portion. The distance in the movement direction between the bottom of the recess B13 formed in the one end portion B11 of the upstream fixing plate B1 and the one end portion B21 of the downstream fixing plate B2 is larger than the outer diameter of the coil portion S1.

Here, in the present embodiment, the spring SP arranged at one end (the right side in the figure) in the width direction of the holder 140 and the spring SP arranged at the other end have the same shape. Therefore, as shown in FIG. 5, in the spring SP arranged on one end side (the right side in the figure) in the width direction of the holder 140, the first arm portion S2 that biases the upstream fixing plate B1 is closer to the second arm portion S3 than the second arm portion S3. It is arranged on the inner side in the width direction. On the other hand, in the spring SP arranged on the other end side in the width direction of the holder 140, the second arm portion S3 that biases the downstream fixing plate B2 is arranged inside the first arm portion S2 in the width direction.

The other end portion B12 of the upstream fixing plate B1 is formed to have a smaller width than the central portion in the width direction of the upstream fixing plate B1. The downstream end of the other end B12 is arranged at the same position in the moving direction as the bottom of the recess B13 of the one end B11. A first arm portion S2 of the spring SP arranged on the other end side is in contact with the other end portion B12 of the upstream fixing plate B1.

A recess B23 recessed toward the downstream side is formed at the upstream end of the other end B22 of the downstream fixing plate B2. The bottom of the concave portion B23 is arranged at the same position in the moving direction as the upstream end of the one end portion B21 of the downstream fixing plate B2. The second arm portion S3 of the spring SP arranged on the other end side enters the recess B23 and contacts the bottom of the recess B23.

That is, the recesses B13 and B23 of the fixing plates B1 and B2 are arranged at positions that engage with the arm portions S2 and S3 positioned on the inner side in the width direction, respectively. Here, when the concave portion is formed corresponding to the arm portion arranged on the outer side in the width direction, it is necessary to separate the end of the fixing plate in the width direction from the concave portion by a predetermined distance in order to secure the strength of the end portion of the fixing plate. Therefore, the length of the fixing plate in the width direction may increase. On the other hand, in the present embodiment, the concave portions B13 and B23 are arranged at positions where they engage with the arm portions S2 and S3 positioned on the inner side in the width direction, so that the fixing plates B1 and B2 are enlarged in the width direction. are restrained from doing so.

Returning to FIG. 4, the tip of the first arm portion S2 and the tip of the second arm portion S3 each have a bent portion S4. The bent portion S4 is formed in an annular shape. A bent portion S4 of the first arm portion S2 protrudes from the first arm portion S2 toward the second arm portion S3. A bent portion S4 of the second arm portion S3 protrudes from the second arm portion S3 toward the first arm portion S2.

The spring SP has a size that does not interfere with the sliding sheet 150 when the fixing device 8 is in the nip state shown in FIG. Specifically, in the state where the spring SP is attached to the holder 140, the end on the rotating body 120 side is located at substantially the same position as the end on the rotating body 120 side of the upstream wall W2 and the downstream wall W4 (or at the end). is located at a position farther from the rotating body 120 than.

The upstream wall W2, the central wall W3 and the downstream wall W4 protrude from the support wall W1 toward the rotor 120. As shown in FIG. The upstream wall W2 functions as a first restricting member that restricts upstream movement of the upstream nip forming member N1 in the moving direction by coming into contact with the upstream pad P1 of the upstream nip forming member N1. The upstream wall W2 is arranged at the upstream end of the support wall W1. The upstream wall W2 extends further outward than the support wall W1 in the width direction, and the end portion on the outer side in the width direction extends away from the nip forming member N. As shown in FIG.

The downstream wall W4 functions as a second restricting member that restricts downstream movement of the downstream nip forming member N2 in the moving direction by contacting the downstream pad P2 of the downstream nip forming member N2. The downstream wall W4 is arranged at the downstream end of the support wall W1. The downstream wall W4 extends further outward than the support wall W1 in the width direction, and the end portion on the outer side in the width direction extends away from the nip forming member N. As shown in FIG.

The central wall W3 is located between the upstream wall W2 and the downstream wall W4 in the direction of movement and at a distance from the upstream wall W2 and the downstream wall W4.

The above-described upstream support surface F1 is arranged between the upstream wall W2 and the central wall W3. Further, the aforementioned downstream support surface F2 is arranged between the central wall W3 and the downstream wall W4. Note that the upstream pad P1 is arranged at a position away from the central wall W3 (see FIG. 5). Also, the downstream pad P2 is arranged at a position away from the central wall W3 (see FIG. 5).

The side wall W5 is arranged between the support wall W1 and the engaging portions 142, 143 in the width direction. The side wall W5 extends in a direction intersecting the width direction, more specifically in a direction perpendicular to it. The side wall W5 connects the widthwise end of the upstream wall W2 and the widthwise end of the downstream wall W4. The side wall W5 is separated from the support wall W1 in the width direction.

The side wall W5 has a notch W7 recessed in a direction away from the rotating body 120 at the end on the rotating body 120 side. The notch W7 is located at a position corresponding to the mounting boss W6 in the moving direction. In other words, the mounting boss W6 is positioned within the range of the notch W7 in the movement direction. The notch W7 faces the mounting boss W6 in the width direction.

The side wall W5 has a first portion W8 located on the upstream side of the notch portion W7 in the moving direction, and a second portion W9 located on the downstream side of the notch portion W7 in the moving direction. The second portion W9 is arranged downstream from the first portion W8 in the moving direction.

The mounting boss W6 is positioned between the first portion W8 and the second portion W9 in the moving direction. The distance between the first portion W8 and the second portion W9 in the movement direction, that is, the length of the notch portion W7 in the movement direction is larger than the outer diameter of the coil portion S1 of the spring SP.

The side wall W5 includes a first protrusion W10 protruding inward in the width direction from the end of the first portion W8 on the rotating body 120 side, and a second protrusion W10 protruding inward in the width direction from the end of the second portion W9 on the rotating body 120 side. It further has two projections W11. The first protrusion W10 protrudes in the width direction from the sidewall W5 toward the upstream pad P1. The first projecting portion W10 restricts movement of the upstream fixed plate B1 toward the rotor 120 side. The second protrusion W11 protrudes in the width direction from the side wall W5 toward the downstream pad P2. The second projecting portion W11 restricts the movement of the downstream fixed plate B2 toward the rotor 120 side.

As shown in FIG. 5, part of the first projecting portion W10 is arranged at the same position as the first arm portion S2 in the moving direction. In other words, part of the first arm portion S2 is positioned within the range of the first projecting portion W10 in the moving direction. Furthermore, in other words, when a part of the first arm portion S2 is projected in the width direction, it overlaps the first projecting portion W10. When the spring SP is slightly tilted or slightly moved in the width direction, the first projecting portion W10 contacts the first arm portion S2 to restrict the tilt and movement. .

A portion of the second projecting portion W11 is arranged at the same position as the second arm portion S3 in the moving direction. In other words, part of the second arm portion S3 is positioned within the range of the second projecting portion W11 in the moving direction. Furthermore, in other words, when a part of the second arm portion S3 is projected in the width direction, it overlaps the second projecting portion W11. When the spring SP is slightly tilted or slightly moved in the width direction, the second projecting portion W11 contacts the second arm portion S3 to restrict the tilt and movement. .

It is preferable that the widthwise distance between the first projecting portion W10 and the first arm portion S2 and the widthwise distance between the second projecting portion W11 and the second arm portion S3 are as small as possible. For example, the above-described interval is preferably three times or less the wire diameter of the spring SP.

The mounting boss W6 extends in the width direction to a position overlapping the first projection W10 and the second projection W11. In other words, the mounting boss W6 protrudes outward in the width direction from the inner end portions in the width direction of the protrusions W10 and W11.

As shown in FIGS. 4 and 5, the other end B12 of the upstream fixing plate B1 has a restricting recess B14 recessed in the moving direction away from the upstream wall W2. In addition, the other end B22 of the downstream fixing plate B2 has a restriction recess B24 that is recessed in the moving direction away from the downstream wall W4.

The upstream wall W2 has a restricting protrusion W21 that fits in the restricting recess B14 and restricts the movement of the upstream fixing plate B1 in the width direction. The downstream wall W4 has a restricting protrusion W41 that fits in the restricting recess B24 and restricts the movement of the downstream fixing plate B2 in the width direction.

The restricting recesses B14, B24 and restricting projections W21, W41 are positioned between the respective ends of the upstream pad P1 and the downstream pad P2 and the mounting boss W6 in the width direction.

As shown in FIGS. 6A and 6B, the restricting protrusions W21 and W41 extend along a predetermined direction. The support wall W1 has through holes Hj and Hk through which the restricting projections W21 and W41 pass. Here, for example, when the regulating projection is projected from the surface of the support wall W1 on the side of the rotating body 120, due to the mold for molding the holder 140, the corner between the regulating projection and the surface of the support wall W1 should be formed. A curved surface or an inclined surface remains. Therefore, in this case, the fixing plates B1 and B2 may float from the support wall W1, or the fixing plates B1 and B2 may rattle in the width direction if the size of the restriction recess is increased to suppress the lifting. be.

In this embodiment, the restriction protrusions W21 and W41 formed on the upstream wall W2 and the downstream wall W4 are formed so as to pass through the through holes Hj and Hk formed on the support wall W1. can be prevented from occurring. Although the through holes Hj and Hk are exemplified in the present embodiment, the present invention is not limited to this. may be formed to protrude from the bottom of the recess. That is, among the surfaces of the support wall W1 on the rotating body 120 side, the surface around the restricting projection may be arranged at a position farther from the rotating body 120 than the other surfaces.

As shown in FIGS. 6A to 6C, the engaging portion 143 on the other end side in the width direction has a pair of clamping walls W12 and a first connecting wall W13 that connects the pair of clamping walls W12. are doing. Each sandwiching wall W12 sandwiches the widthwise end of the base portion 211 of the first stay 210 in the movement direction. Each holding wall W12 extends widthwise outward from the side wall W5.

The first connecting wall W<b>13 is located on the side opposite to the rotating body 120 with respect to the widthwise end of the base portion 211 and is in contact with the widthwise end of the base portion 211 . The first connecting wall W13 connects the widthwise outer ends of the holding walls W12. The first connecting wall W13 is separated from the side wall W5 in the width direction. As a result, a gap is formed between the first connecting wall W13 and the side wall W5, and the load input portion 211A (see FIG. 7) of the first stay 210 can be exposed downward through this gap. The buffer member BF (see FIG. 7) described above can be attached to the load input portion 211A exposed downward.

The holder 140 further has a second connecting wall W14 connecting the pair of holding walls W12, and a reinforcing portion WA connecting the holding wall W12 and the side wall W5. The second connecting wall W14 is located on the side opposite to the first connecting wall W13 with respect to the widthwise end of the base portion 211 . The second connecting wall W14 is separated from the base portion 211 in a predetermined direction. The second connecting wall W14 is separated from the first connecting wall W13 in the width direction and connected to the side wall W5.

The reinforcing portion WA is a portion for reinforcing the sandwiching wall W12, and is provided for each sandwiching wall W12. Since the two reinforcing parts WA have a symmetrical structure in the movement direction, only one reinforcing part WA will be explained below, and the explanation of the other side will be omitted.

The reinforcement part WA is arranged parallel to one holding wall W12 and connected to the side wall W5, and the first wall W15 is arranged parallel to the side wall W5 and connects the first wall W15 and one holding wall W12. and a second wall W16. The first wall W15, the second wall W16, the clamping wall W12 and the side wall W5 form a rectangular cylindrical portion, and a hole W17 is formed inside these walls to penetrate in a predetermined direction. This hole W17 is a hole with which the leg portion BF2 (see FIG. 7) of the cushioning member BF described above is engaged.

As shown in FIG. 6C, the distance D1 between the first portion W8 and the mounting boss W6 in the moving direction is larger than the wire diameter of the spring SP (see FIG. 4). Further, the distance D2 in the moving direction between the second portion W9 and the mounting boss W6 is also larger than the wire diameter of the spring SP.

As shown in FIG. 6A, each holding wall W12 has a through hole W18 and a notch W19. The through hole W18 penetrates the holding wall W12 in the moving direction. The notch W19 is formed at the end of the clamping wall W12 on the rotating body 120 side. The through hole W18 and the notch W19 are arranged on the side opposite to the side wall W5 with respect to the second wall W16. The through hole W18 and the notch W19 are arranged at the same position in the width direction. A movement restricting member R shown in FIGS. 13 and 14 is attached to the through hole W18 and the notch W19.

The movement restricting member R is a member that restricts the movement of the first stay 210 with respect to the holder 140 in the width direction. The movement restricting member R is a torsion spring made of metal wire. As shown in FIG. 13, the movement restricting member R has a coil portion R1, a first arm portion R2 extending from one end of the coil portion R1, and a second arm portion R3 extending from the other end of the coil portion R1. there is

A widthwise end of the base portion 221 of the first stay 210 has a through hole Hi. The through hole Hi is arranged outside the load input portion 211A in the width direction.

As shown in FIG. 14, the first arm portion R2 of the movement restricting member R is inserted through the holding walls W12 and the through holes W18, Hi of the first stay 210 and engaged with the through holes W18, Hi. The second arm portion R3 of the movement restricting member R engages with the notch W19 of each clamping wall W12.

The engaging portion 142 on one end in the width direction differs from the engaging portion 143 on the other end in that it does not have the through hole W18 and the notch W19. It has the same structure as the part 143 .

As shown in FIG. 7, the holder body 141 further has a plurality (16) of ribs W30, two first extending walls W31, and two second extending walls W32. A plurality of ribs W30 protrude from the support wall W1 toward the side opposite to the nip forming member N. As shown in FIG.

The plurality of ribs W30 extend in the movement direction and are arranged at intervals in the width direction. The widthwise interval between the ribs W30 is smaller than the widthwise interval between the two first extending walls W31. Each rib W30 is arranged symmetrically in the width direction. A plurality of ribs W<b>30 contact the first stay 210 and the second stay 220 .

Specifically, the base portion 211 of the first stay 210 contacts all the ribs W30. The second stay 220 has four protrusions CV that come into contact with some (four) ribs W30 of the plurality of ribs W30.

The convex portion CV protrudes from the end of the base portion 221 of the second stay 220 on the holder 140 side. Each protrusion CV is arranged symmetrically in the width direction with respect to the center C1 of the second stay 220 in the width direction. A distance D3 from the convex portion CV to the center C1 in the width direction of the second stay 220 is smaller than a distance D4 from the convex portion CV to the end of the second stay 220 in the width direction. Here, in FIG. 7, the distance relationship is shown representatively for the projection CV that is farthest from the center C1. Note that the distance relationship is similarly satisfied for the convex portion CV closest to the center C1.

The base portion 221 of the second stay 220 has a plurality of holes Hc2, Hd2, He2 which will be detailed later. Each convex portion CV is arranged at a position different from each hole Hc2, Hd2, He2 in the width direction.

The two first extending walls W31 are arranged symmetrically in the width direction with respect to the center C2 of the holder 140 in the width direction. Each second extending wall W32 is arranged upstream of each first extending wall W31 with a space therebetween in the movement direction. The first extending wall W31 and the second extending wall W32 are arranged closer to the center C2 in the width direction of the holder 140 (holder main body 141) than the engaging portion 142 in the width direction. Specifically, the distance D5 from the first extension wall W31 and the second extension wall W32 to the center C2 in the width direction of the holder 140 (holder main body 141) is the distance from the first extension wall W31 and the second extension wall W32. It is smaller than the distance D6 to the engaging portion 142.

Here, FIG. 7 shows the distance relationship between the extending walls W31 and W32 on the left side of the drawing with respect to the center C2 and the engaging portion 142. As shown in FIG. Note that the distance relationship is similarly satisfied between the extending walls W31 and W32 and the engaging portion 143 on the right side of the drawing with respect to the center C2.

As shown in FIGS. 8A and 8B, the first extending wall W31 extends from the downstream end of the support wall W1 to the opposite side of the nip forming member N. As shown in FIGS. The first extending wall W31 extends to the opposite side of the nip forming member N than the second extending wall W32. The first extending wall W31 contacts the downstream surface Fa of the base portion 211 of the first stay 210 .

The second extending wall W32 extends from the supporting wall W1 to the side opposite to the nip forming member N. As shown in FIG. The second extending wall W32 extends on the opposite side of the nip forming member N from the rib W30. The second extending wall W32 contacts the upstream surface Fb of the base portion 211 of the first stay 210 . That is, the first extending wall W31 and the second extending wall W32 sandwich the base portion 211 in the movement direction.

As shown in FIG. 8B, the base portion 211 of the first stay 210 is arranged closer to the downstream nip forming member N2 in the movement direction. Specifically, in the moving direction, the distance D7 from the center C3 of the base portion 211 to the upstream end of the downstream pad P2 in the moving direction is the distance from the center C3 in the width direction of the base portion 211 to the downstream end of the upstream pad P1 in the moving direction. smaller than the distance D8.

As shown in FIG. 9A, the upstream guide G1 has an outer peripheral wall G11, a plurality of ribs G12, a plurality (five) of bosses G13, two fastening portions G14, and two projections G15. are doing. The outer peripheral wall G11 is an arc-shaped wall when viewed in cross section, and has an upstream guide surface Fu on the outside.

The rib G12 protrudes from the surface of the outer peripheral wall G11 opposite to the upstream guide surface Fu. The end surfaces of the plurality of ribs G12 are surfaces for sandwiching the upstream end portion 151A of the sliding sheet 150 with the second stay 220 (see FIG. 9B).

The boss G13, the fastening portion G14, and the protrusion G15 protrude downstream in the moving direction from the surface of the outer peripheral wall G11 opposite to the upstream guide surface Fu. The boss G13, the fastening portion G14, and the protrusion G15 are arranged in a line with an interval in the width direction. The boss G13, the fastening portion G14 and the projection G15 are formed in a cylindrical shape. The boss G13, the fastening portion G14, and the protrusion G15 are arranged at the same position as the rib G12 in the width direction.

The protrusion G15 protrudes further downstream in the movement direction than the fastening portion G14. The boss G13 protrudes further downstream in the moving direction than the protrusion G15.

The boss G13 is a boss for fixing the upstream guide G1 to the first stay 210 together with the downstream guide G2 (see FIG. 10(b)). The plurality of bosses G13 are arranged at intervals in the width direction. Each boss G13 is arranged at a position different from the upstream guide surface Fu. Specifically, each boss G13 is arranged on the opposite side of the outer peripheral wall G11 from the upstream guide surface Fu. Each boss G13 is arranged at the end of the upstream guide G1 opposite to the rotating body 120 in a predetermined direction.

The fastening portion G14 is a portion for fixing the upstream guide G1 to the second stay 220 (see FIG. 10(c)). The fastening portion G14 is arranged between the boss G13 arranged on the outermost side in the width direction among the five bosses G13 and the boss G13 adjacent to the boss G13.

The protrusion G15 is a part for positioning the upstream guide G1 on the second stay 220. As shown in FIG. The protrusions G15 are arranged on one end side and the other end side in the width direction of the upstream guide G1. Specifically, five bosses G13 are arranged between two protrusions G15 in the width direction.

The upstream end portion 151A of the sliding sheet 150 has five engaging holes Hc1 through which the five bosses G13 pass, two holes Hd1 corresponding to the two fastening portions G14, and two holes He1 through which the two projections G15 pass. have. Each of the holes Hc1, Hd1, He1 is an elongated hole elongated in the width direction.

The engagement hole Hc1 is a hole that engages with the boss G13. When the engaging hole Hc1 is engaged with the boss G13, the upstream end 151A of the sliding sheet 150 is sandwiched and fixed between the upstream guide G1 and the second stay 220, as shown in FIG. 9B. It is

The base portion 221 of the second stay 220 has five holes Hc2 through which the five bosses G13 pass, two holes Hd2 corresponding to the two fastening portions G14, and two holes He2 through which the two protrusions G15 pass. ing. Hole Hc2 is larger than the outer diameter of boss G13.

The hole Hd2 is a hole through which a shaft portion SC32 (see FIG. 10(c)) of a third screw SC3, which will be described later, passes. The hole Hd2 is smaller than the outer diameter of the fastening portion G14 and larger than the outer diameter of the shaft portion SC32 of the third screw SC3.

One of the two holes He2 is a round hole and the other is an elongated hole elongated in the width direction. As a result, even if the upstream guide G1 made of resin thermally expands in the width direction with respect to the second stay 220 made of metal, it is possible to suppress the distortion of the upstream guide G1.

The base portion 221 has holes Hf at both ends thereof for fixing the above-described crimping members SW (see FIG. 3). Each hole Hc2, Hd2, He2 described above is arranged between two holes Hf in the width direction.

As shown in FIG. 10(b), the upstream wall 213 of the first stay 210 has a first hole Hc3 through which the boss G13 passes. The first hole Hc3 is larger than the outer diameter of the boss G13. As shown in FIG. 3, five first holes Hc3 are provided corresponding to the five bosses G13. The first hole Hc3 is an elongated hole elongated in the width direction.

As shown in FIG. 10B, the base portion 221 of the first stay 210 has a second hole Hc4 corresponding to the boss G13. The second hole Hc4 is a hole for fixing the downstream guide G2 to the base portion 221 of the first stay 210 . The shaft portion SC12 of the first screw SC1 passes through the second hole Hc4. The second hole Hc4 is larger than the outer diameter of the shaft portion SC12 of the first screw SC1. As shown in FIG. 12, five second holes Hc4 are provided corresponding to the five bosses G13. The second hole Hc4 is located at a position different from each rib W30 in the width direction.

As shown in FIG. 10(b), the downstream guide G2 has a hole Hc5 corresponding to the boss G13. The shaft portion SC12 of the first screw SC1 passes through the hole Hc5. The hole Hc5 is larger than the outer diameter of the shaft portion SC12 of the first screw SC1. As shown in FIG. 7, five holes Hc5 are provided corresponding to the five bosses G13.

The downstream guide G2 has five fixed portions G22 having holes Hc5. The fixed portion G22 is a portion for fixing the downstream guide G2 to the base portion 221 of the first stay 210 . The fixed portion G22 is arranged on the upstream side in the movement direction of the hook engaging portion G21 described above. In addition, each fixing portion G22 is spaced apart in the width direction, and is arranged between the adjacent hook engaging portions G21.

As shown in FIG. 10(b), the boss G13 has a screw hole G16 into which the first screw SC1 is screwed at the tip on the downstream side in the moving direction. The screw hole G16 has a concave shape with a bottom.

Here, the screw hole G16 may be a hole in which a thread groove is cut in advance on the inner peripheral surface of the cylindrical boss G13, or a first thread when the first screw SC1 is screwed into the cylindrical boss G13. It may be a hole threaded by one screw SC1. The same applies to a screw hole G17 (see FIG. 10(c)), which will be described later.

The boss G13 is in contact with the base portion 211 of the first stay 210 through the respective holes Hc1, Hc2, Hc3 of the sliding sheet 150, the second stay 220 and the upstream wall 213 of the first stay 210. As shown in FIG. In addition, the boss G13 is arranged with a gap from the edges of the holes Hc2 and Hc3 when the fixing device 8 is assembled.

The first screw SC1 passes through the downstream guide G2 and holes Hc5 and Hc4 of the base portion 211 of the first stay 210 and is screwed into the screw hole G16 of the boss G13. Thus, the downstream guide G2 and the base portion 211 of the first stay 210 are held between the tip of the boss G13 and the head SC11 of the first screw SC1. In other words, in a state in which the base portion 211 of the first stay 210 is sandwiched between the tip of the boss G13 and the fixed portion G22 of the downstream guide G2, the first screw SC1 is fastened to the tip of the boss G13. A guide G1 and a downstream guide G2 are fixed to the base portion 211 . That is, the upstream guide G1, the first stay 210 and the downstream guide G2 are fastened together by the first screw SC1. In addition, the first screw SC1 is arranged in a state of being spaced apart from the edges of the holes Hc5 and Hc4 when fastened to the tip of the boss G13.

As shown in FIG. 10(c), the fastening portion G14 has a threaded hole G17 into which the third screw SC3 is screwed at the tip on the downstream side in the moving direction. The screw hole G17 has a concave shape with a bottom.

The fastening portion G14 is in contact with the base portion 221 of the second stay 220 through the hole Hd1 of the sliding sheet 150. As shown in FIG. The third screw SC3 passes through the hole Hd2 of the base portion 221 of the second stay 220 and is screwed into the screw hole G17 of the fastening portion G14. As a result, the base portion 221 of the second stay 220 is held between the tip of the fastening portion G14 and the head SC31 of the third screw SC3, and the upstream guide G1 is fixed to the second stay 220 with the third screw SC3. be.

As shown in FIG. 11, the head SC11 of the first screw SC1, the head SC21 of the second screw SC2, and the head SC31 of the third screw SC3 face downstream in the movement direction. The protrusion G15 is positioned farther from the center C1 of the second stay 220 than the first screw SC1 in the width direction.

The connecting member CM is positioned closer to the load input portion 211A than the center C1 of the first stay 210 in the width direction. Here, since the widthwise center of the second stay 220 and the widthwise center of the first stay 210 are located at the same position in the widthwise direction, they are denoted by the same reference numeral "C1".

Specifically, the connecting member CM is arranged between the center C1 of the first stay 210 and the load input portion 211A in the width direction. A distance D9 from the connecting member CM to the load input portion 211A is smaller than a distance D10 from the connecting member CM to the center C1 of the first stay 210. As shown in FIG.

As shown in FIG. 13, the fixing device 8 further includes a side frame 83, a bracket 84, and a pressing mechanism 300. As shown in FIG.

The side frame 83 is a frame that supports the heating unit 81 and the pressure unit 82 . The side frame 83 is made of metal or the like. The side frame 83 has a spring engaging portion 83A that engages with one end portion of a biasing member 320, which will be described later, and a notch portion 83B for passing the widthwise end portion of the base portion 211 of the first stay 210. ing.

The side frame 83 also has two projections 83C for positioning the bracket 84 and a hole 83D for fixing the bracket 84. As shown in FIG. Each protrusion 83C is arranged on one side and the other side in the moving direction with respect to the notch 83B. Each hole 83D is arranged on one side and the other side in the movement direction with respect to the notch 83B.

The bracket 84 has a first elongated hole 84A that supports the first stay 210 movably in a predetermined direction, two second elongated holes 84C for positioning, and two third elongated holes 84D for fixing. ing. The first elongated hole 84A is elongated in a predetermined direction. The engaging portion 143 of the holder 140 is engaged with the first long hole 84A (see FIG. 14).

The second elongated hole 84C and the third elongated hole 84D are elongated holes elongated in the moving direction. Each of the second elongated holes 84C is arranged on one side and the other side in the movement direction with respect to the first elongated holes 84A. Each of the third long holes 84D is arranged on one side and the other side in the moving direction with respect to the first long hole 84A.

Each protrusion 83C can be engaged with each second long hole 84C. The bracket 84 can move in the moving direction with respect to the side frame 83 in a state where each second long hole 84C is engaged with each protrusion 83C. Accordingly, by aligning the position of the first long hole 84A of the bracket 84 with a predetermined mark formed on the side frame 83, for example, the pressurizing unit 82 can be satisfactorily positioned on the side frame 83.

After positioning the bracket 84, the bracket 84 is fixed to the side frame 83 by screwing the third elongated holes 84D and the holes 83D with screws. The aforementioned movement restricting member R is in contact with the bracket 84 from the outside in the width direction (see FIG. 14). Thereby, the holder 140 and the first stay 210 are positioned in the width direction with respect to the side frame 83 .

The pressing mechanism 300 includes a pressing arm 310 and a biasing member 320 . The pressing arm 310 is a member for pressing the first stay 210 via the buffer member BF. The pressing arm 310 is an L-shaped plate member made of metal or the like. The pressing arm 310 includes a hole 311 that is rotatably supported by the side frame 83, a spring engaging portion 312 that engages with the other end of the biasing member 320, and an engaging hole 313 that engages with the buffer member BF. and

A hole 311 is located at one end of the push arm 310 . A spring engaging portion 312 is arranged at the other end of the pressing arm 310 . The engagement hole 313 is arranged near the bent portion of the pressing arm 310 .

The biasing member 320 is a member for biasing the first stay 210 toward the rotating body 120 . In this embodiment, biasing member 320 is an extension coil spring.

As shown in FIG. 15, a cam 85 is rotatably provided on the side frame 83 . The cam 85 is a member for switching the state of the fixing device 8 between the nip state and the nip release state.

Here, the nip state refers to a state in which a predetermined nip pressure is applied between the heating unit 81 and the pressure unit 82 (state shown in FIG. 2). The nip release state is a state in which no nip pressure is applied between the heating unit 81 and the pressure unit 82, or a nip pressure smaller than a predetermined nip pressure is applied.

When the cam 85 is separated from the pressing arm 310, the fixing device 8 is in the nip state. When the cam 85 rotates approximately 90 degrees counterclockwise from the orientation shown in FIG. It will be in release state.

Next, the effects of the fixing device 8 according to this embodiment will be described.
As shown in FIGS. 2 and 4, in the nip state, the fixing plates B1 and B2 are biased toward the walls W2 and W4 by the springs SP, so that the pads P1 and P2 are attached to the walls W2 and W4. and restricts the movement of the nip forming members N1 and N2. Similarly, in the nip release state, the pads P1 and P2 are in contact with the walls W2 and W4, restricting the movement of the nip forming members N1 and N2. Therefore, even if the nip state and the nip release state are repeated, the positions of the nip forming members N1 and N2 with respect to the holder 140 can be kept constant. The position of the entire nip portion NP can be stabilized.

Further, even if there is a manufacturing error in the nip forming members N1, N2, for example, a mounting error in adhering the pads P1, P2 to the fixing plates B1, B2, the urging force of the spring SP allows the pads P1, P2 to contacts the walls W2 and W4, the positions of the pads P1 and P2 with respect to the holder 140 can be kept constant, and the positions of the nip portions NP1 and NP2 can be stabilized.

Both ends of the fixing plates B1 and B2 in the width direction are also biased toward the support wall W1 by springs SP. Therefore, when the support surfaces F1 and F2 of the support wall W1 protrude (curve) toward the rotating body 120 as in the present embodiment, the nip forming members N1 and N2 are aligned with the support surfaces F1. , F2. That is, the surfaces of the pads P1 and P2 facing the rotating body 120 can be curved after the fixing device 8 is assembled, without the surfaces facing the rotating body 120 of the pads P1 and P2 being curved. . Further, since the manufacturing error of the holder 140 made of resin or the like is smaller than the manufacturing error of the pads P1 and P2 made of rubber, the surfaces of the pads P1 and P2 on the rotating body 120 side are Manufacturing variations in the pressure distribution in the width direction of the nip portion NP can be suppressed more than in the case of a curved surface.

According to the above, the following effects can be obtained in this embodiment.
Since the nip forming members N1 and N2 are urged and brought into contact with the walls W2 and W4, each nip portion NP1 can be operated regardless of manufacturing errors of the nip forming members N1 and N2 and repetition of the nip state and the nip release state. , NP2 can be stabilized. In addition, compared to, for example, a V-shaped leaf spring, the spring SP has a coil portion S1 with one or more turns. It is possible to suppress plastic deformation of the spring SP.

By configuring the springs SP to contact the fixed plates B1 and B2, compared to a configuration in which the springs are contacted to the pads, the springs SP do not deform the shapes of the pads P1 and P2. The positions of the parts NP1 and NP2 can be more stabilized.

By providing the holder 140 with a mounting boss W6 that fits into the coil portion S1, the spring SP can be assembled to the holder 140 simply by mounting the coil portion S1 of the spring SP on the mounting boss W6. can be easily done.

By locating the mounting boss W6 farther from the rotating body 120 than the fixed plates B1 and B2 in the predetermined direction, the nip forming members N1 and N2 can be pressed against the holder 140 by the spring SP. It is possible to prevent the nip forming members N1 and N2 from coming off the holder 140. As shown in FIG.

In the above embodiment, the mounting boss W6 is positioned between the end B11 of the upstream fixing plate B1 and the end B21 of the downstream fixing plate B2 in the moving direction, and the end B11 of the upstream fixing plate B1 and the downstream fixing plate The distance in the moving direction from the end B21 of B2 is larger than the outer diameter of the coil portion S1. As a result, the coil portion S1 of the spring SP can be attached to the mounting boss W6 through the space between the upstream fixing plate B1 and the downstream fixing plate B2, so that the assembling workability of the spring SP can be improved. Further, since the fixing plates B1 and B2 can be pressed against the holder 140 by the spring SP, the nip forming members N1 and N2 can be more reliably prevented from falling off from the holder 140, and variations in the nip pressure distribution can be suppressed. .

In the above-described embodiment, the length of the notch portion W7 in the moving direction is larger than the outer diameter of the coil portion S1. As a result, the coil portion S1 of the spring SP can be attached to the mounting boss W6 through the notch portion W7, so that the assembling workability of the spring SP can be improved.

A part of each of the projecting portions W10 and W11 is arranged at the same position as the arm portions S2 and S3 in the movement direction, and the mounting boss W6 extends to a position overlapping with each of the projecting portions W10 and W11 in the width direction. , the projections W10 and W11 can suppress the inclination of the spring SP and the falling off from the mounting boss W6.

Since the restricting protrusions W21 and W24 are fitted in the restricting recesses B14 and B24 of the fixing plates B1 and B2, it is possible to restrict the movement of the fixing plates B1 and B2 in the width direction. In addition, since the restricting recesses B14, B24 and restricting protrusions W21, W41 are positioned between the respective ends of the pads P1, P2 and the mounting boss W6 in the width direction, the restricting recesses and restricting protrusions, for example, can be mounted. The size of the fixing device 8 in the width direction can be reduced compared to the case where it is positioned outside the boss in the width direction.

Since the tip of each arm portion S2, S3 of the spring SP has a bent portion S4, for example, when the spring SP is held in a compressed state using tweezers, the bent portion S4 does not engage with the tweezers. , it is possible to prevent the spring SP from coming off the tweezers.

Since the bent portion S4 is formed in an annular shape, for example, when the spring SP is held in a compressed state using tweezers, the tip of the tweezers can be passed through the annular bent portion S4. drop-off can be further suppressed.

Since the upstream guide G1, the first stay 210 and the downstream guide G2 are fastened together with the first screw SC1, for example, the upstream guide is fixed to the first stay with a predetermined screw and the downstream guide is fixed to the first stay with another screw. The number of screws can be reduced compared to a fixed structure.

Since there is a gap between the boss G13 and the edge of the first hole Hc3, even if the first stay 210 is deformed, it is possible to prevent the first stay 210 from contacting the boss G13. , deformation of the upstream guide G1 can be suppressed.

Since the screw hole G16 has a concave shape with a bottom, even if chips are generated when the first screw SC1 is fastened to the screw hole G16, the chips can be retained in the screw hole G16. can.

If the load input portions 211A are located at both ends of the first stay 210 in the width direction, the amount of deformation at the center of the first stay 210 in the width direction tends to be greater than at the ends. In the above-described embodiment, the connecting member CM is arranged at a position closer to the load input portion 211A than the center of the first stay 210 in the width direction. As compared with the case, the deformation of the second stay 220 can be suppressed.

In addition, since the connecting member CM is arranged between the center C1 of the first stay 210 and the load input portion 211A in the width direction, the second Since the length of the stay 220 in the width direction can be shortened, the weight of the fixing device 8 can be reduced.

Since the crimping member SW is crimped to the second stay 220, the flatness of the first stay 210 to which the load is input can be maintained, compared with a structure in which the crimping member is crimped to the first stay, for example.

Since the upstream guide G1 is fixed to the first stay 210 with the first screw SC1 and fixed to the second stay 220 with the third screw SC3, the upstream guide G1 can be firmly supported by the stays 210 and 220. can.

The heads SC11 to SC31 of the screws SC1 to SC3 all face the downstream side in the movement direction, so that the fastening directions of the screws SC1 to SC3 are the same, which facilitates the assembly work of each member. can. Further, for example, when the head of the first screw faces upstream, it is necessary to form a through hole for the head of the first screw to escape in the upstream guide. In this case, the edge of the through-hole of the upstream guide surface on the outer periphery of the upstream guide becomes an edge, and the edge may become a conveying resistance of the endless belt. In contrast, in the above-described embodiment, since the head SC11 of the first screw SC1 is oriented downstream in the moving direction, there is no need to form a through hole in the upstream guide G1 for the head SC11 of the first screw SC1 to escape. It is possible to suppress formation of an edge on the upstream guide surface Fu.

Since the projection G15 for positioning the upstream guide G1 is arranged on the outer side in the width direction of the first screw SC1, the upstream guide G1 is positioned closer to the second stay than, for example, in a structure in which the projection is arranged on the inner side of the first screw in the width direction. 220 can be prevented from being assembled.

Since the first stay 210 and the second stay 220, which are separate bodies, are brought into contact with the holder 140, the stays 210 and 220 are different from each other, for example, in a structure where each end of two walls of a U-shaped stay is brought into contact with the holder. The position of the contact surface with the holder 140 can be arranged with high accuracy, and variations in the nip pressure can be suppressed. Further, since the first stay 210 has the bent hemming portion HB, the rigidity of the first stay 210 can be increased, and the force of the biasing member 320 can be transmitted to the holder 140 satisfactorily. Furthermore, since the connecting member CM is arranged at a position different from the bent hemming portion HB, it is possible to suppress deterioration of the strength of the portion of the base portion 211 whose rigidity is increased by the bent hemming portion HB.

Since the convex portion CV of the second stay 220 is arranged at a position different from the holes Hc2, Hd2, and He2 in the width direction, even if force is applied to the convex portion CV from the holder 140, the deformation of the second stay 220 is prevented. can be suppressed, and variations in pressure distribution can be suppressed.

Since the first stay 210 is directly positioned on the holder 140 by engaging the ends of the first stay 210 to which the load is input with the engaging portions 142 and 143 of the holder 140, the first stay 210 to which the load is input The positional accuracy in the moving direction of the holder 140 with respect to the stay 210 can be stabilized, and uneven nip pressure distribution can be suppressed.

In addition, since the first connecting wall W13 is located on the side opposite to the rotating body 120 with respect to the end of the first stay 210 in the width direction and contacts the first stay 210, in the load input direction (predetermined direction), The first stay 210 can be sandwiched between the holder main body 141 and the first connecting wall W13. Therefore, the positional accuracy of the holder 140 with respect to the first stay 210 can be stabilized. Moreover, the holder 140 and the first stay 210 can be properly assembled temporarily, and the assembling workability can be improved.

Since the second connecting wall W14 that connects the pair of holding walls W12 is provided, the rigidity of the engaging portions 142 and 143 can be increased.

For example, in a configuration in which the second connecting wall contacts the first stay, the distribution of the nip pressure in the width direction may change. You can prevent problems like this from happening.

Since the clamping wall W12 is reinforced by the reinforcing portion WA, the rigidity of the engaging portions 142 and 143 can be increased.

Since the first extending wall W31 is in contact with the downstream surface Fa of the first stay 210, the holder 140 can be prevented from tilting downstream in the movement direction.

When the second extension wall W32 contacts the upstream surface Fb of the first stay 210, the first stay 210 is sandwiched between the first extension wall W31 and the second extension wall W32. It is possible to suppress the deformation and twisting of the .

Since the first extending wall W31 and the second extending wall W32 are located closer to the center C2 in the width direction of the holder main body 141 than the engaging portions 142 and 143 in the width direction, It is possible to suppress the deformation of the center of the holder 140 with respect to the part in the moving direction.

The first stay 210 and the pair of holding walls W12 are provided with the through holes W18 and Hi through which the movement restricting member R is inserted, so that the first stay 210 can be positioned in the width direction with respect to the holder 140 .

Since the plurality of ribs W30 are brought into contact with the first stay 210, the contact of each rib W30 with the first stay 210 is less than that of a structure in which, for example, a flat surface formed in the holder that is long in the width direction is brought into contact with the entire end of the first stay. The accuracy of the surface can be improved, and the nip pressure distribution in the width direction can be made substantially uniform. In addition, since the rib W30 extends in the movement direction, the support wall W1 is more easily deformed along the first stay 210 than when a rib that is long in the width direction is provided, so that the nip pressure distribution in the width direction is substantially uniform. can be Here, the contact surface Ft of the first stay 210 can have a central convex shape (arc shape) in which the center in the width direction protrudes toward the holder 140 from the end portions in the width direction when viewed from the moving direction. In this case, the effects described above can be particularly exhibited.

Since the first stay 210 that receives the force from the biasing member 320 is arranged near the downstream nip forming member N2, the nip pressure at the downstream nip portion NP2 can be made appropriate. Here, in order to separate the sheet S from the rotating body 120, the downstream nip forming member N2 has a higher pressure peak than the upstream nip forming member N1. Therefore, by arranging the first stay 210 closer to the downstream nip forming member N2, such a pressure peak can be favorably produced.

Since the second stay 220 has the protrusion CV that contacts some of the ribs W30 among the plurality of ribs W30, the first stay 210 and the second stay 220 can support the support wall W1 satisfactorily.

Since the convex portion CV is arranged near the center C1 in the width direction of the second stay 220, it is possible to suppress deformation of the center portion in the width direction of the support wall W1 toward the second stay 220 side.

The second hole Hc4 of the first stay 210 is arranged at a position different from each rib W30 in the width direction. Since there is no Hc4, deformation of the first stay 210 can be suppressed, and the nip pressure can be further stabilized.

Since the slide sheet 150 has the elastically deformable hooks 152, the hooks 152 can be easily engaged with the openings Hg of the hook engaging portions G21 by roughly aligning the hooks 152 with the openings Hg. Therefore, the assembly work of the sliding sheet 150 can be easily performed.

The width of the tip of the tip 152A of the hook 152 and the width of the neck 152B are smaller than the width of the opening Hg, and the maximum width of the tip 152A is larger than the width of the opening Hg. can be inserted into the opening Hg, and the hook 152 can be made difficult to come off from the opening Hg.

Since the length of the neck portion 152B is greater than the thickness of the hook engaging portion G21, the downstream end portion 151B of the sliding sheet 150 can be fixed to the downstream guide G2 with play.

Since the distance between the hook engaging portion G21 and the first stay 210 is larger than the length of the tip portion 152A, the tip portion 152A of the hook 152 does not hit the first stay 210 when the tip portion 152A is inserted into the opening Hg. Therefore, the tip portion 152A can be easily inserted into the opening Hg.

Since the fixing portion G22 of the downstream guide G2 and the first stay 210 is arranged between two adjacent hook engaging portions G21, when the downstream guide G2 is fixed to the first stay 210, the hook engaging portion Since G21 does not get in the way, fixing work can be easily performed.

Tension is applied to the upstream end of the sliding sheet 150 by pulling the endless belt 130 and the sliding sheet 150 downstream at the nip portion NP, but tension is less likely to be applied to the downstream end of the sliding sheet 150 . In this embodiment, since the hook 152 is provided at the downstream end portion 151B of the sliding sheet 150 so that tension is not applied, the sliding sheet 150 can be moved by simply engaging the hook 152 with the opening Hg without using a screw or the like. The downstream end 151B can be fixed to the downstream guide G2. Therefore, the downstream end portion 151B of the sliding sheet 150 can be easily fixed while reducing the number of parts, for example, compared to a structure in which the downstream end of the sliding sheet is fixed with a screw.

The engagement hole Hc1 formed in the upstream end portion 151A of the sliding sheet 150 engages with the boss G13 of the upstream guide G1, and the upstream end portion 151A of the sliding sheet 150 engages between the upstream guide G1 and the second stay 220. Since the upstream end portion 151A of the sliding sheet 150 can be fixed to the upstream guide G1 by being sandwiched between them, the fixing operation of the upstream end portion 151A of the sliding sheet 150 can also be easily performed.

Since the sliding sheet 150 is arranged to cover the upstream guide surface Fu, sliding resistance between the upstream guide G1 and the endless belt 130 can be reduced.

The present invention is not limited to the above-described embodiments, and can be used in various forms as exemplified below.

In the above embodiment, the halogen lamp was exemplified as the heater, but the heater may be, for example, a carbon heater.

In the above-described embodiment, a cylindrical roller with a built-in heater 110 was exemplified as a rotating body, but the present invention is not limited to this, and for example, an endless belt whose inner peripheral surface is heated by a heater. good too. Alternatively, an external heating method in which a heater is arranged outside the rotating body to heat the outer peripheral surface of the rotating body, or an IH (Induction Heating) method may be used. Alternatively, a heater may be arranged inside the endless belt to indirectly heat the rotating body in contact with the outer peripheral surface of the endless belt. Also, the rotating body and the endless belt may each incorporate a heater.

In the above-described embodiment, the sliding sheet 150 is provided between the endless belt 130 and each nip forming member N, but the present invention is not limited to this. good too. A sliding sheet without hooks may be provided between the endless belt and the nip forming member. Also, the downstream end of the sliding sheet may be a free end that is not fixed to any member.

In the above embodiment, two nip forming members N1 and N2 are provided, but the present invention is not limited to this, and the number of nip forming members may be one.

In the above embodiment, the nip forming member is composed of the pad and the fixing plate, but the present invention is not limited to this, and the nip forming member may be composed of only the pad, for example. Also, the pad may be made of a hard material such as resin or metal that does not deform elastically even when pressurized.

In the above embodiment, the regulating members (walls W2, W4) are provided integrally with the holder 140, but the present invention is not limited to this, and the regulating members may be members separate from the holder, for example.

In the above-described embodiment, each arm portion S2, S3 of the spring SP is provided with the bent portion S4, but the present invention is not limited to this. You may provide a bending part only in the arm part of.

Although the bent portion S4 is formed in an annular shape in the above embodiment, the present invention is not limited to this, and the bent portion may be formed in an arc shape or a V shape, for example.

In the above-described embodiment, the connecting member CM is composed of the crimping member SW and the second screw SC2, but the present invention is not limited to this, and for example, a member that is screwed to each stay may be used as the connecting member. .

In the above embodiment, the biasing member 320 is a tension coil spring, but the present invention is not limited to this, and the biasing member may be, for example, a compression coil spring, a torsion spring, a leaf spring, or the like.

In the above embodiment, a torsion spring was exemplified as the movement restricting member R, but the present invention is not limited to this. It may consist of bolts and nuts.

In the above embodiment, the number of protrusions CV provided on the second stay 220 is four, but the present invention is not limited to this, and the second stay may have at least one protrusion.

Although the holder 140 and the stay 200 are illustrated as supporting members in the above embodiment, the present invention is not limited to this, and the supporting member may be, for example, only the holder or only the stay. Alternatively, the holder and the stay may be integrated.

In the above embodiment, the belt guide G is composed of two guides G1 and G2, but the present invention is not limited to this. may be composed of Also, the upstream guide and the downstream guide may be configured integrally.

Although the stay 200 is composed of two stays 210 and 220 in the above embodiment, the present invention is not limited to this, and the number of stays may be one or three or more.

In the above embodiment, the hook 152 is provided on the downstream end 151B of the sliding sheet 150, but the present invention is not limited to this, and the sliding sheet has a hook on at least one of the upstream end and the downstream end. It's fine if you do.

In the above-described embodiment, the hook engaging portion G21 with which the hook 152 engages is provided in the downstream guide G2, but the present invention is not limited to this, and the hook engaging portion includes the upstream guide, the holder, the first stay and the second stay. It may be provided in either of the two stays.

In the above embodiment, the tip portion 152A of the hook 152 protrudes from the neck portion 152B on both sides in the width direction, but the present invention is not limited to this, and the tip portion of the hook protrudes only on one side in the width direction from the neck portion. may protrude into

In the above embodiment, the upstream end 151A of the sliding sheet 150 is fixed to the upstream guide G1, but the present invention is not limited to this. It may be fixed to either the stay or the second stay.

In the above embodiment, the sliding sheet 150 is arranged so as to cover the upstream guide surface Fu, the nip forming member N, and the downstream guide surface Fd, but the present invention is not limited to this, and the sliding sheet covers at least the nip. It is sufficient if the forming member is covered. That is, the belt guide may be brought into contact with the inner peripheral surface of the endless belt.

Each element described in the above embodiment and modifications may be implemented in any combination.

8 fixing device 110 heater 120 rotating body 130 endless belt 140 holder 210 first stay N nip forming member NP nip portion W1 support wall W30 rib

Claims (13)

a heater;
a rotating body heated by the heater;
an endless belt;
a nip forming member that sandwiches the endless belt between itself and the rotating body to form a nip portion;
a holder that holds the nip forming member;
a first stay that supports the holder;
The holder is
a support wall located on the opposite side of the nip forming member to the rotating body and supporting the nip forming member;
a plurality of ribs projecting from the support wall and contacting the first stay;
The plurality of ribs extend in the moving direction of the endless belt in the nip portion and are arranged at intervals in the width direction of the endless belt ,
further comprising a biasing member that biases the first stay toward the rotating body;
The nip forming member is
an upstream nip forming member that sandwiches the endless belt between itself and the rotating body to form an upstream nip portion;
a downstream nip forming member arranged downstream in the movement direction with respect to the upstream nip forming member, and forming a downstream nip portion with the endless belt sandwiched between itself and the rotating body;
In the movement direction, the distance from the center in the movement direction of the portion of the first stay that supports the rib to the upstream end of the downstream nip forming member in the movement direction is A fixing device , wherein the distance from the center in the moving direction to the downstream end of the upstream nip forming member in the moving direction is smaller . a heater;
a rotating body heated by the heater;
an endless belt;
a nip forming member that sandwiches the endless belt between itself and the rotating body to form a nip portion;
a holder that holds the nip forming member;
a first stay that supports the holder;
The holder is
a support wall located on the opposite side of the nip forming member to the rotating body and supporting the nip forming member;
a plurality of ribs projecting from the support wall and contacting the first stay;
The plurality of ribs extend in the moving direction of the endless belt in the nip portion and are arranged at intervals in the width direction of the endless belt,
further comprising a second stay arranged upstream of the first stay in the moving direction and supporting the holder;
the second stay has a plurality of protrusions contacting some of the plurality of ribs,
The distance from the first protrusion farthest from the widthwise center of the second stay to the widthwise center of the second stay among the plurality of protrusions is the distance from the first protrusion to the second stay. and the distance to the end of the width direction of the fixing device. further comprising a downstream guide that guides the inner peripheral surface of the endless belt on the downstream side of the nip forming member in the moving direction;
the first stay has a hole for fixing the downstream guide,
3. The fixing device according to claim 1 , wherein the hole is located at a different position from the rib in the width direction. The holder is
a holder body including the support wall and the rib;
An engaging portion that engages with the widthwise end of the first stay, is arranged at a position different from the endless belt in the widthwise direction, and extends from the widthwise end of the holder main body. an engaging portion;
has
The engaging portion is
a pair of sandwiching walls sandwiching the first stay in the movement direction;
4. The fixing device according to claim 1, further comprising a first connecting wall that connects the pair of holding walls. 5. The fixing device according to claim 4 , wherein the first connecting wall is positioned opposite to the rotating body with respect to the widthwise end of the first stay and contacts the first stay. Device. The holder has a second connecting wall that connects the pair of holding walls,
6. The fixing device according to claim 5 , wherein the second connecting wall is positioned opposite to the first connecting wall with respect to the widthwise end of the first stay. 7. The fixing device according to claim 6 , wherein the second connecting wall is separated from the first stay. The holder body has a side wall disposed between the support wall and the engaging portion in the width direction and extending in a direction intersecting the width direction,
The holder has a reinforcing portion that connects one of the holding walls and the side wall,
The reinforcing part is
a first wall arranged parallel to one of the holding walls and connected to the side walls;
a second wall arranged parallel to the side walls and connecting the first wall and one of the holding walls;
8. The fixing device according to any one of claims 4 to 7 , comprising: The holder main body has a first extending wall extending from the supporting wall in a direction opposite to the nip forming member,
the first stay has a downstream surface positioned downstream in the movement direction,
The fixing device according to any one of claims 4 to 8 , wherein the first extending wall contacts the downstream surface. The holder main body has a second extending wall extending from the supporting wall in a direction opposite to the nip forming member,
the first stay has an upstream surface positioned upstream in the movement direction,
The fixing device according to claim 9 , wherein the second extending wall contacts the upstream surface. 10. The first extending wall and the second extending wall are arranged at a position closer to the center of the holder body in the width direction than the engaging portion in the width direction. The fixing device according to . further comprising a movement restricting member that restricts movement of the first stay with respect to the holder in the width direction;
12. The fixing device according to claim 4 , wherein the first stay and the pair of holding walls have through holes through which the movement restricting member is inserted. 13. The fixing device according to claim 12 , wherein the movement restricting member is a metal wire.

Images