JP6056950B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device that thermally fixes a developer image transferred to a recording sheet.

  As a fixing device used in an electrophotographic image forming apparatus, a fixing film, a heater, a heating plate (nip plate) that forms a nip portion between the pressure roller and the fixing film, and radiant heat from the heater Is provided with a reflector that reflects the nip to the nip plate (see, for example, Patent Document 1).

JP 2006-47769 A

  By the way, when a heater (such as a halogen heater) in which a gas and a heat source are enclosed in a glass tube is used as a heater, a tip portion formed when the gas is sealed protrudes radially outward from the surface of the glass tube. To be formed. The direction of the tip portion protruding from the surface of the glass tube in this way affects the position and size of the reflecting plate and nip plate, and is therefore a very important factor in reducing the size of the fixing device. It was.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device that can be downsized by specifying the direction of a chip portion.

  The present invention that solves the above-described problems is a fixing device that thermally fixes a developer image transferred to a recording sheet, a cylindrical fixing film, a heating element disposed inside the fixing film, and the fixing The fixing film is sandwiched between the nip plate disposed so as to be in sliding contact with the inner surface of the film, a reflection plate that reflects radiant heat from the heating element toward the nip plate, and the nip plate. A backup member that forms a nip portion with the film, and the heating element is a heater in which a gas and a heat source are enclosed in a glass tube, and the tip portion formed when the gas is enclosed in the glass tube Is provided so as to protrude radially outward from the surface of the glass tube, and the size of the cross-sectional shape of the glass tube including the tip portion in the facing direction in which the nip plate and the heater face each other, Serial to be smaller than the size of the cross-sectional shape in the direction orthogonal to the opposing direction, wherein the tip portion is characterized in that it is arranged facing the predetermined direction.

  According to the present invention, the tip of the glass tube including the tip portion in the facing direction where the nip plate and the heater face each other is made smaller than the size of the sectional shape in the direction orthogonal to the facing direction. Since the portion is directed in a predetermined direction, the reflecting plate and the nip plate can be brought close to the surface of the glass tube of the heater in the facing direction, and the fixing device can be downsized in this direction.

  According to the present invention, the reflecting plate and the nip plate can be brought close to the surface of the glass tube of the heater in the facing direction, so that the fixing device can be downsized.

1 is a diagram illustrating a schematic configuration of a laser printer including a fixing device according to an embodiment of the present invention. 1 is a diagram illustrating a schematic configuration of a fixing device according to an embodiment of the present invention. It is a perspective view of a halogen lamp, a nip plate, a reflecting plate, and a stay. It is the figure which looked at the nip plate, the reflecting plate, and the stay from the conveyance direction. The figure which shows the form which inclined the chip | tip part diagonally (a), the figure (b) which shows the form which turned the chip | tip part back, and the figure (c) which shows the form which provided two halogen lamps.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the schematic configuration of the laser printer 1 (image forming apparatus) including the fixing device 100 according to the embodiment of the present invention will be described first, and then the detailed configuration of the fixing device 100 will be described.

<Schematic configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes a main body housing 2 in which a paper sheet 3 as an example of a recording sheet is fed, an exposure device 4, and a toner image (developer) on the paper P. And the fixing device 100 for thermally fixing the toner image on the paper P.

  In the following description, the direction will be described with reference to the user who uses the laser printer. That is, the right side in FIG. 1 is “front”, the left side is “rear”, the front side is “left”, and the back side is “right”. Also, the vertical direction in FIG.

  The paper feed unit 3 is provided in the lower part of the main body housing 2, and includes a paper feed tray 31 that accommodates the paper P, a paper pressing plate 32 that lifts the front side of the paper P, a paper feed roller 33, and a paper feed pad 34. And paper dust removing rollers 35 and 36 and a registration roller 37 are mainly provided. The paper P in the paper feed tray 31 is brought close to the paper feed roller 33 by the paper pressing plate 32 and separated one by one by the paper feed roller 33 and the paper feed pad 34, and the paper dust removing rollers 35, 36 and the registration roller 37. Then, it is conveyed toward the process cartridge 5.

  The exposure apparatus 4 is arranged at the upper part in the main body housing 2 and mainly includes a laser light emitting unit (not shown), a polygon mirror 41 that is rotationally driven, lenses 42 and 43, and reflecting mirrors 44, 45, and 46. In preparation. In the exposure apparatus 4, the laser light (see the chain line) based on the image data emitted from the laser light emitting part is reflected or passed through the polygon mirror 41, the lens 42, the reflecting mirrors 44 and 45, the lens 43 and the reflecting mirror 46 in this order. The surface of the photosensitive drum 61 is scanned at high speed.

  The process cartridge 5 is disposed below the exposure apparatus 4 and is detachably mounted on the main body housing 2 through an opening formed when the front cover 21 provided on the main body housing 2 is opened. Yes. The process cartridge 5 includes a drum unit 6 and a developing unit 7.

  The drum unit 6 mainly includes a photosensitive drum 61, a charger 62, and a transfer roller 63. The developing unit 7 is configured to be detachably attached to the drum unit 6, and includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and a toner that contains toner (developer). The housing part 74 is mainly provided.

In the process cartridge 5, the surface of the photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser light from the exposure device 4, whereby image data is transferred onto the photosensitive drum 61. An electrostatic latent image based on is formed. Further, the toner in the toner container 74 is supplied to the developing roller 71 via the supply roller 72 and enters between the developing roller 71 and the layer thickness regulating blade 73 to form a thin layer of a certain thickness on the developing roller 71. It is carried on.

  The toner carried on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photosensitive drum 61. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 61. Thereafter, the paper P is conveyed between the photosensitive drum 61 and the transfer roller 63, whereby the toner image on the photosensitive drum 61 is transferred onto the paper P.

  The fixing device 100 is provided behind the process cartridge 5. The toner image (toner) transferred onto the paper P is thermally fixed onto the paper P by passing through the fixing device 100. The paper P on which the toner image is thermally fixed is discharged onto the paper discharge tray 22 by the transport rollers 23 and 24.

<Detailed configuration of fixing device>
As shown in FIG. 2, the fixing device 100 includes a fixing film 110, a halogen lamp 120 as an example of a heating element, a nip plate 130, a reflection plate 140, and a pressure roller 150 as an example of a backup member, Stay 160 is mainly provided.

  In the following description, the transport direction (substantially front-rear direction) of the paper P is simply referred to as “transport direction”, and the width direction (substantially left-right direction) of the paper P is simply referred to as “width direction”. Further, the facing direction (substantially vertical direction) in which the nip plate 130 and the halogen lamp 120 face each other is simply referred to as “facing direction”.

  The fixing film 110 is an endless (cylindrical) film having heat resistance and flexibility, and rotation is guided by guide members (not shown) at both ends in the width direction.

  The halogen lamp 120 is a heating element that heats the toner on the paper P by heating the nip plate 130 and the fixing film 110, and has a predetermined interval from the inner surface of the fixing film 110 and the nip plate 130 inside the fixing film 110. It is arranged with a gap. The halogen lamp 120 includes a glass tube 121, a filament 122 as an example of a heat source provided in the glass tube 121, and a halogen gas 123 as an example of a gas sealed in the glass tube 121. Yes.

  The glass tube 121 is provided with a tip portion 124 formed when the halogen gas 123 is sealed so as to protrude radially outward from the surface of the glass tube 121. In this tip portion 124, the size L1 of the cross-sectional shape of the glass tube 121 including the tip portion 124 in the vertical direction (the facing direction) is the size of the cross-sectional shape in the front-rear direction (the direction perpendicular to the facing direction). It is arranged facing forward (upstream in the transport direction) so as to be smaller than L2.

  Accordingly, the upper walls 141A and 166 of the reflecting plate 140 and the stay 160 can be lowered to a low position (position close to the glass tube 121), so that the fixing device 100 can be downsized in the vertical direction. Yes. Further, since the tip portion 124 is directed forward, the front portion (end portion 131B) of the nip plate 130 with respect to the nip portion N1 can be extended forward, so that the portion extending forward is slid with the fixing film 110. In contact therewith, it is possible to preheat the fixing film 110 before entering the nip portion N1.

Here, the nip portion N1 is a portion that sandwiches the paper P between the nip plate 130 (specifically, the fixing film 110) and the pressure roller 150, and is a portion that transfers heat of the fixing film 110 to the paper P. The central portion of the nip portion N1 is positioned on a line connecting the center of the glass tube 121 and the center of the pressure roller 150 in order to efficiently heat the nip portion N1 with the halogen lamp 120. . Therefore, when the tip portion 124 is directed forward as in the present embodiment, the front portion of the nip plate 130 with respect to the nip portion N1 is extended forward, and the above-described preheating can be performed.

  The nip plate 130 is a plate-like member that receives the pressing force of the pressure roller 150 and transmits the radiant heat from the halogen lamp 120 to the toner on the paper P via the fixing film 110, and the cylindrical fixing film 110. It is arrange | positioned so that it may slidably contact with the inner surface.

  The nip plate 130 has a thermal conductivity higher than that of a steel stay 160, which will be described later. For example, the nip plate 130 is formed by bending an aluminum plate or the like into a substantially U shape in sectional view. More specifically, the nip plate 130 mainly includes a base portion 131 that extends along the conveying direction and a bent portion 132 that is bent upward in a cross-sectional view.

  The base portion 131 is bent so that the central portion 131A in the transport direction is convex toward the pressure roller 150 side (downward) from both end portions 131B. In addition, the end 131B on the front side of the center part 131A in the both end parts 131B is formed longer in the front-rear direction than the end part 131B on the rear side, so that the preheating described above can be performed. Note that the inner surface (upper surface) of the base portion 131 may be painted black or provided with a heat absorbing member. According to this, the radiant heat from the halogen lamp 120 can be efficiently absorbed.

  As shown in FIG. 3, the nip plate 130 further includes an insertion portion 133 that extends in a flat plate shape from the right end portion of the base portion 131, and an engagement portion 134 that is formed at the left end portion of the base portion 131. The engaging portion 134 is formed in a U shape in a side view, and an engaging hole 134B is provided in a side wall portion 134A formed by bending upward.

  As shown in FIG. 2, the reflecting plate 140 reflects the radiant heat from the halogen lamp 120 (radiant heat radiated mainly in the front-rear direction and the upward direction) toward the nip plate 130 (the inner surface of the base portion 131). It is a member and is arranged at a predetermined interval from the halogen lamp 120 so as to surround the halogen lamp 120 inside the fixing film 110.

  By collecting the radiant heat from the halogen lamp 120 to the nip plate 130 with such a reflector 140, the radiant heat from the halogen lamp 120 can be used efficiently, and the nip plate 130 and the fixing film 110 can be heated quickly. Can do.

  The reflection plate 140 is formed by curving an aluminum plate or the like in a substantially U shape in cross section, for example, having a high infrared and far infrared reflectance. More specifically, the reflecting plate 140 mainly has a reflecting portion 141 having a curved shape (substantially U shape in cross section) and a flange portion 142 extending from both ends of the reflecting portion 141 along the transport direction. In order to increase the thermal reflectance, the reflection plate 140 may be formed using a mirror-finished aluminum plate or the like.

  As shown in FIG. 3, a total of four flange-like locking portions 143 are formed at both ends in the width direction of the reflector plate 140 (only three are shown). The locking portion 143 is located above the flange portion 142. As shown in FIG. 4, when the nip plate 130, the reflecting plate 140, and the stay 160 are assembled, a plurality of contact portions 163 of the stay 160 described later are provided. It arrange | positions so that it may pinch | interpose (adjacent to the outermost contact part 163A in the width direction).

As a result, even if the reflecting plate 140 tries to move left and right due to vibration or the like when the fixing device 100 is driven, the position of the reflecting plate 140 in the width direction is restricted by the locking portion 143 coming into contact with the contact portion 163A. The As a result, the positional deviation in the width direction of the reflecting plate 140 can be suppressed.

  As shown in FIG. 2, the pressure roller 150 is a member that forms a nip portion N <b> 1 with the fixing film 110 by sandwiching the fixing film 110 with the nip plate 130. Has been placed. More specifically, the pressure roller 150 presses the nip plate 130 through the fixing film 110 to form a nip portion N1 between the pressure roller 150 and the fixing film 110.

  The pressure roller 150 is configured to be driven to rotate by a driving force transmitted from a motor (not shown) provided in the main body housing 2, and to rotate with the fixing film 110 (or paper P). The fixing film 110 is driven and rotated by the frictional force.

  The sheet P on which the toner image is transferred is conveyed between the pressure roller 150 and the heated fixing film 110 (nip portion N1), whereby the toner image (toner) is thermally fixed.

  The stay 160 is a member that secures the rigidity of the nip plate 130 by supporting both end portions 131B of the nip plate 130 (base portion 131) in the transport direction, and follows the outer surface shape of the reflecting plate 140 (reflecting portion 141). It has a shape (substantially U shape in cross section) and is arranged so as to cover the reflector 140. Such a stay 160 has relatively high rigidity, for example, is formed by bending a steel plate or the like into a substantially U shape in cross-sectional view.

  At the lower ends of the front wall 161 and the rear wall 162 of the stay 160, as shown in FIG. 3, a plurality of contact portions 163 formed in a substantially comb shape are provided.

  Further, a substantially L-shaped locking portion 165 extending downward and further toward the left is provided at the right end portions of the front wall 161 and the rear wall 162 of the stay 160. Further, a holding portion 167 is provided at the left end of the stay 160 and extends leftward from the upper wall 166 and is bent into a substantially U shape in a side view. Engagement bosses 167B (only one is shown) projecting inward are provided on the inner surfaces of the side wall portions 167A of the holding portion 167.

  As shown in FIGS. 2 and 3, a total of four abutting bosses 168 projecting inward are provided at both ends in the width direction of the inner surfaces of the front wall 161 and the rear wall 162 of the stay 160. The abutting boss 168 abuts on the reflecting plate 140 (the reflecting portion 141) in the transport direction. Accordingly, even if the reflection plate 140 tries to move back and forth due to vibrations when the fixing device 100 is driven, the position of the reflection plate 140 in the transport direction is restricted by contacting the contact boss 168. As a result, it is possible to suppress displacement of the reflecting plate 140 in the transport direction.

  When the reflecting plate 140 and the nip plate 130 are assembled to the stay 160 described above, the reflecting plate 140 is first attached to the stay 160 so as to be fitted. Since the abutting boss 168 is provided on the inner surfaces of the front wall 161 and the rear wall 162 of the stay 160, the reflecting plate 140 is temporarily held by the stay 160 when the abutting boss 168 contacts the reflecting plate 140. The

  Thereafter, as shown in FIG. 4, the insertion portion 133 of the nip plate 130 is inserted between the locking portions 165 of the stay 160 to engage the base portion 131 (both end portions 131B) with the locking portions 165, and then Then, the engaging portion 134 (engaging hole 134B) of the nip plate 130 and the holding portion 167 (engaging boss 167B) of the stay 160 are engaged.

Thereby, the both ends 131 </ b> B of the base portion 131 are supported by the locking portion 165 and the engaging portion 134 is held by the holding portion 167, so that the nip plate 130 is held by the stay 160.
The reflecting plate 140 is held by the stay 160 in a state where the flange portion 142 is sandwiched between the nip plate 130 and the stay 160.

  Although illustration is omitted, the stay 160 that holds the nip plate 130 and the reflection plate 140 and the halogen lamp 120 are held by a guide member that guides the rotation of the fixing film 110. Then, by fixing the guide member to a housing (not shown) of the fixing device 100, the fixing film 110, the halogen lamp 120, the nip plate 130, the reflection plate 140, and the stay 160 are held on the housing of the fixing device 100. Yes.

  In the present embodiment, the reflecting plate 140 is supported in a state where the flange portion 142 is sandwiched between the nip plate 130 and the stay 160 as shown in FIG. As a result, even if the reflection plate 140 tries to move up and down due to vibrations when the fixing device 100 is driven, the flange portion 142 is sandwiched between the nip plate 130 and the stay 160 so that the reflection plate 140 is moved in the vertical direction. The position of is regulated. As a result, it is possible to suppress the positional deviation of the reflecting plate 140 in the vertical direction, and to fix the position of the reflecting plate 140 with respect to the nip plate 130.

According to the above, the following effects can be obtained in the present embodiment.
Since the tip portion 124 is directed forward so that the size L1 of the cross-sectional shape of the glass tube 121 including the tip portion 124 in the vertical direction is smaller than the size L2 of the cross-sectional shape in the front-back direction, The reflector 140 (upper wall 141A) and the nip plate 130 can be brought close to the surface of the glass tube 121 of the halogen lamp 120. Therefore, the position of the upper wall 166 of the stay 160 can be lowered to a lower position, and the fixing device 100 can be downsized in the vertical direction.

  By directing the tip portion 124 forward, a front portion of the nip plate 130 with respect to the nip portion N1 can be extended forward, so that the fixing film 110 can be preheated by the portion extending forward, and heat fixing. Can be improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the above-described embodiment, the tip portion 124 is directed forward (upstream in the transport direction), but the condition that the vertical size L1 of the cross-sectional shape of the glass tube 121 is smaller than the front-back size L2 is satisfied. Any orientation is possible as long as it is a predetermined orientation. For example, as shown in FIG. 5A, the tip portion 124 may be tilted so as to be directed obliquely upward to the extent that the relationship of L1 <L2 is satisfied, or as shown in FIG. The tip portion 124 may be rearward (downstream in the transport direction).

  Further, as shown in FIG. 5C, two halogen lamps 120 may be arranged side by side in the vertical direction (opposing direction). According to this, the nip plate 130 can be heated more quickly by the two halogen lamps 120.

  In this embodiment, the halogen lamp 120 disposed on the upper side (one in the facing direction) is directed rearward (downstream in the transport direction) and is disposed on the lower side (the other in the facing direction). It is desirable to direct 120 tip portions 124 forward (upstream in the transport direction). According to this, compared to the structure in which the glass tubes 121 of the two halogen lamps 120 are arranged in the vertical direction, the two halogen lamps 120 can be brought closer to the vertical direction, so that the two fixing devices 200 are not enlarged. The halogen lamp 120 can improve the heating performance (fixing performance).

In the above-described embodiment, the stay 160 is provided. However, the present invention is not limited to this, and a structure without a stay may be employed.
In the embodiment, the halogen lamp 120 (halogen heater) is exemplified as the heating element. However, the present invention is not limited to this. For example, an infrared heater or a carbon heater may be used.

  In the embodiment, the pressure roller 150 is exemplified as the backup member. However, the pressure roller 150 is not limited thereto, and may be a belt-shaped pressure member, for example. In the above embodiment, the configuration in which the nip portion N1 is formed by pressing the nip plate 130 by the pressure roller 150 (backup member) is illustrated, but the present invention is not limited to this, and the nip plate presses the backup member. It is good also as a structure which forms a nip part.

  In the embodiment, the paper P such as plain paper or postcard is exemplified as the recording sheet. However, the recording sheet is not limited to this, and may be, for example, an OHP sheet.

  In the above-described embodiment, the laser printer 1 is exemplified as the image forming apparatus including the fixing device of the present invention. However, the present invention is not limited to this. For example, an LED printer that performs exposure using LEDs may be used. It may be a copying machine or a multifunction machine. In the above-described embodiment, an image forming apparatus that forms a monochrome image is exemplified. However, the present invention is not limited to this, and an image forming apparatus that forms a color image may be used.

DESCRIPTION OF SYMBOLS 100 Fixing device 110 Fixing film 120 Halogen lamp 121 Glass tube 122 Filament 123 Halogen gas 124 Tip part 130 Nip plate 150 Pressure roller 160 Stay N1 Nip part P Paper

Claims (8)

A cylindrical fixing film;
A heating element disposed inside the fixing film;
A nip plate disposed in sliding contact with the inner surface of the fixing film and facing the heating element in a first direction ;
A reflector that reflects radiant heat from the heating element toward the nip plate;
A backup member that forms a nip portion with the fixing film by sandwiching the fixing film with the nip plate, and a developer image while conveying a recording sheet in a predetermined conveying direction at the nip portion. A fixing device for fixing the toner image on the recording sheet,
The heating element has a glass tube and a heat source disposed in the glass tube, and the glass tube of the heating element is viewed from the longitudinal direction of the glass tube from the outer peripheral surface of the glass tube in the transport direction. Having a tip portion projecting upstream or downstream of
The glass tube of the heating element is a second direction in which the dimension in the first direction is orthogonal to the first direction in a cross section cut by a plane passing through the tip portion and orthogonal to the longitudinal direction of the glass tube. Smaller than the dimensions in
The fixing device according to claim 1, wherein the tip portion is directed to a side opposite to the nip plate in the first direction. The tip portion includes a fixing device according to claim 1, characterized in that is directed to the upstream side in the transport direction. The tip portion includes a fixing device according to claim 1, characterized in that is directed to the downstream side in the transport direction.   The reflecting plate reflects the radiant heat radiated toward the conveying direction and the radiant heat radiated toward the direction opposite to the nip plate in the first direction toward the nip plate. The fixing device according to any one of claims 1 to 3, wherein the fixing device is characterized in that:   The fixing device according to claim 4, wherein the reflecting plate has a substantially U shape in a cross section cut by the plane.   The fixing device according to claim 5, wherein the reflection plate includes a substantially U-shaped reflection portion and a flange portion that extends from both ends of the reflection portion along the conveyance direction.   With a stay,
  The fixing device according to claim 6, wherein the flange portion is held by the stay while being sandwiched between the nip plate and the stay.   The back-up member is a roller, and a center portion of the nip portion is located on a line connecting a center of the glass tube and a center of the roller in a cross section cut by the plane. The fixing device according to claim 1.

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