JP2012141410A - Fixation device - Google Patents

Abstract

A fixing device capable of suppressing the slip of a fixing film and fixing the recording sheet satisfactorily is provided.
The fixing device includes a flexible fixing film 110, a nip plate 130 disposed so as to be in sliding contact with the inner surface of the fixing film 110, and a driving force supplied to the nip plate via the fixing film 110. A pressure roller 150 that forms a nip region with the pressure roller 150, and is in pressure contact with both the inside of the fixing film 110 and the pressure roller 150 and receives a driving force of the pressure roller 150. And a nip roller 170 that is driven to rotate.
[Selection] Figure 5

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 nip plate that forms a nip portion between a cylindrical fixing film, a heater disposed in the fixing film, and a pressure roller via the fixing film (For example, refer to Patent Document 1). Specifically, in this fixing device, the pressure roller is driven by a motor, and the fixing film rotates following the pressure roller.

JP-A-8-248791

  However, in the above-described technique, when the recording sheet passes between the fixing film and the pressure roller, the driving force from the pressure roller is not sufficiently transmitted to the fixing film, and the running performance of the fixing film is reduced. (The fixing film slips). As described above, when the fixing film slips, there has been a problem that the developer image cannot be satisfactorily fixed on the recording sheet.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing device that can prevent the fixing film from slipping and can satisfactorily fix the recording sheet.

  In order to achieve the above-described object, the fixing device of the present invention is supplied with a flexible cylindrical member, a nip member disposed so as to be in sliding contact with the inner surface of the cylindrical member, and a driving force. A backup member that forms a nip region with the nip member via a cylindrical member, wherein the backup member is in pressure contact with both the inner side of the cylindrical member and the backup member. It is characterized by comprising a roller that is driven and rotated by receiving the driving force.

  According to the fixing device configured as described above, the roller receives the driving force of the backup member and is driven to rotate, so that the roller applies the driving force to the inner surface of the cylindrical member, thereby suppressing the slip of the cylindrical member. can do.

  According to the present invention, the slip of the cylindrical member can be suppressed, so that the fixing to the recording sheet can be performed satisfactorily.

1 is a side sectional view showing a laser printer provided with a fixing device according to a first embodiment of the present invention. 1 is a diagram illustrating a schematic configuration of a fixing device according to a first embodiment of the present invention. It is a perspective view of a nip roller, a nip plate, a reflecting plate, and a stay. FIG. 3 is a diagram of the fixing device viewed from a conveyance direction. It is a perspective view of a fixing device. It is a schematic diagram which shows the connection part of a nip roller and a pressure roller. FIG. 6 is a side sectional view of a fixing device according to a second embodiment of the present invention.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of the laser printer 1 (image forming apparatus) including the fixing device 100 of the present invention will be described, and then a 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. A process cartridge 5 for transferring the image) and a fixing device 100 for 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 1. 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 as an example of a cylindrical member, a halogen lamp 120, a nip plate 130 as an example of a nip member, a reflection plate 140, and an example of a backup member. Pressure roller 150, stay 160, and nip roller 170 as an example of a roller.

  The fixing film 110 is an endless (cylindrical) film having heat resistance and flexibility, and both ends of the fixing film 110 are guided by a guide member 180 (see FIG. 5). That is, the fixing device 100 includes the guide member 180 that regulates the end surface of the fixing film 110. The fixing film 110 is in sliding contact with the nip plate 130 via grease. Depending on the material of the fixing film 110 and the nip plate 130, the grease may not necessarily be applied.

  The halogen lamp 120 is a known heating element that heats the toner on the paper P by heating the nip plate 130 and the fixing film 110. Inside the fixing film 110, a predetermined amount of heat is supplied from the inside of the fixing film 110 and the nip plate 130. They are arranged at intervals.

  The nip plate 130 is a plate-like member that receives radiant heat from the halogen lamp 120, and is disposed so as to be in sliding contact with the inner surface of the cylindrical fixing film 110. The nip plate 130 transmits the radiant heat received from the halogen lamp 120 to the toner on the paper P through the fixing film 110.

  The nip plate 130 has a thermal conductivity higher than that of a steel stay 160 described later, and is configured to be planar, for example, an aluminum plate. The upper surface 130A of the nip plate 130 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 extending in a flat plate shape from the right end portion and an engagement portion 134 formed at the left end portion. 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 reflector 140 reflects the radiant heat from the halogen lamp 120 (mainly radiant heat reflected in the front-rear direction or the upward direction) toward the nip plate 130 (the upper surface 130A of the nip plate 130). This member is disposed 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 by 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 includes a reflecting portion 141 having a curved shape (substantially U-shaped in cross section) and a flange portion 142 extending from both ends of the reflecting portion 141 along the outer side in the front-rear 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 of the reflection plate 140 in the left-right direction (the width direction of the paper P) (only three are shown). The locking portion 143 is disposed 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 left-right direction).

  As a result, even if the reflection plate 140 tries to move left and right due to vibrations when the fixing device 100 is driven, the position of the reflection plate 140 in the left-right direction is restricted by the locking portion 143 coming into contact with the contact portion 163A. The As a result, it is possible to suppress the displacement of the reflecting plate 140 in the left-right direction.

  As shown in FIGS. 2 and 4, the pressure roller 150 is an elastically deformable member that is longer in the left-right direction than the fixing film 110, and is disposed below the nip plate 130. The pressure roller 150 is urged toward the nip plate 130 by the first urging means 152.

  As the configuration of the first urging unit 152, a publicly known one can be arbitrarily adopted. As an example, as shown in FIG. 1, one end 153 </ b> A is swingably supported by the casing 101 of the fixing device 100. The arm portion 153 and the spring 154 can be used. The arm portion 153 holds a bearing 151 whose other end portion 153B rotatably supports the pressure roller 150, and one end of a spring 154 is engaged with an intermediate portion between the one end portion 153A and the other end portion 153B. . The other end of the spring 154 is locked to the casing 101, whereby the other end 153 </ b> B of the arm portion 153, that is, the pressure roller 150 is always urged upward.

  As shown in FIG. 2, the pressure roller 150 is elastically deformed by being urged toward the nip plate 130 by the first urging means 152, and the nip plate 130 is in this elastically deformed state. A nip region is formed between the fixing film 110 and the fixing film 110. That is, the pressure roller 150 forms a nip region with the nip plate 130 via the fixing film 110.

  The pressure roller 150 is connected to the motor M through a plurality of gears so that the driving force is supplied from the motor M provided in the main body housing 2 and is rotated. The fixing film 110 is driven to rotate by the frictional force with the film 110 (or paper P).

  Specifically, as shown in FIG. 1, the fixing device 100 includes a driving gear 155, a planetary gear 156, an input gear 157 connected to the motor M, and a swing arm that is omitted from the reference numerals. The driving gear 155 is fixed to the end of the rotating shaft of the pressure roller 150. The input gear 157 is rotatably supported by the casing 101, and the rotation center is immovable with respect to the casing 101. The planetary gear 156 meshes with the drive gear 155 and the input gear 157, and is rotatably supported by a swing arm that connects the rotation shaft of the input gear 157 and the rotation shaft of the planetary gear 156. .

  In the fixing device having a plurality of gears as described above, when the driving force is transmitted from the motor M to the input gear 157, the driving force is transmitted to the driving gear 155 via the planetary gear 156, and the pressure roller 150. Is driven to rotate. Further, at this time, the planetary gear 156 has a force that circulates the input gear 157, so that the planetary gear 156 is pressed against the driving gear 155 and meshed therewith. In order to reliably press the planetary gear 156 against the driving gear 155, a pulling spring that urges the planetary gear 156 toward the driving gear 155 may be provided on the swing arm.

  As shown in FIG. 2, the stay 160 is a member that secures the rigidity of the nip plate 130 by supporting both end portions 130 </ b> C of the nip plate 130 in the front-rear direction via flange portions 142 of the reflection plate 140. The stay 160 has a shape (substantially U shape in cross section) along the outer surface shape of the reflecting plate 140 (reflecting portion 141) and is disposed so as to cover the reflecting plate 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.

  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 left-right 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 (reflecting portion 141) in the front-rear direction. As a result, 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 front-rear direction is restricted by contacting the contact boss 168. As a result, it is possible to suppress the displacement of the reflector plate 140 in the front-rear direction.

  The nip rollers 170 are provided outside the stay 160 at two locations on the upstream side and the downstream side in the paper conveyance direction with respect to the nip plate 130, and as shown in FIG. 5, both the inside of the fixing film 110 and the pressure roller 150. And is driven to rotate by receiving the driving force of the pressure roller 150.

  Specifically, the nip roller 170 is formed in a columnar shape having a substantially constant diameter that is longer in the left-right direction than the fixing film 110 and the pressure roller 150 (see FIG. 4), and both end portions thereof can rotate to the bearing 171. It is supported by. Both ends of the nip roller 170 protrude outside the fixing film 110 and the guide member 180 and are in contact with both the inside of the fixing film 110 and the outer periphery of the pressure roller 150. The nip roller 170 extends axially outward from the peripheral surface of the pressure roller 150.

  As shown in FIG. 6, the bearing 171 of the nip roller 170 and the bearing 151 of the pressure roller 150 are examples of the second urging unit provided separately from the first urging unit 152. The tension springs 190 are connected to each other. As a result, the nip roller 170 and the pressure roller 150 are attracted to each other.

  In this way, the means (tensile spring 190) for urging the nip roller 170 toward the pressure roller 150 is used as the first urging means 152 for generating the urging force between the pressure roller 150 and the nip plate 130. Are provided separately from each other, so that the urging force between the pressure roller 150 and the nip plate 130 and the urging force of the nip roller 170 to the pressure roller 150 can be easily controlled individually.

  The guide member 180 has a groove 181 formed at the lower end thereof along the urging direction of the nip roller 170 in the depth direction. By disposing the nip roller 170 in the groove 181, the nip roller 170 can be prevented from moving in the front-rear direction along with the rotation of the pressure roller 150, and the urging direction of the nip roller 170 can be defined.

  In the fixing device 100 configured as described above, the sheet P on which the toner image is transferred is conveyed between the pressure roller 150 and the heated fixing film 110 (nip region), whereby the toner image (toner) ) Will be heat-fixed. At this time, even if the frictional force between the fixing film 110 and the pressure roller 150 or between the fixing film 110 and the paper P decreases, the nip roller 170 is driven to rotate by receiving the driving force of the pressure roller 150, and the fixing film 110. Since the nip roller 170 gives an auxiliary driving force to the inner surface of the fixing film 110, the slip of the fixing film 110 can be suppressed.

According to the above, the following effects can be obtained in the present embodiment.
Since the fixing device 100 includes a nip roller 170 that is pressed against both the inside of the fixing film 110 and the pressure roller 150 and is driven to rotate by receiving the driving force of the pressure roller 150, the pressure roller 150 and the fixing film 110 are provided. Even when the paper P is being transported during this period, the nip roller 170 can apply a driving force to the inner surface of the fixing film 110 and suppress the slip of the fixing film 110.

  The means for urging the nip roller 170 toward the pressure roller 150 (the tension spring 190) is the first urging means 152 for generating the urging force between the pressure roller 150 and the nip plate 130. By providing them separately, it is easy to individually control the urging force between the pressure roller 150 and the nip plate 130 and the urging force of the nip roller 170 to the pressure roller 150.

  Further, since the nip roller 170 is provided on the upstream side and the downstream side in the paper conveyance direction from the nip plate 130, the paper P is compared with the case where the nip roller 170 is provided only on either the upstream side or the downstream side. It is possible to increase the conveying force.

  Since the nip roller 170 extends to the outside of the peripheral surface of the pressure roller 150, the end of the nip roller 170 does not bite into the pressure roller 150, and the durability of the pressure roller 150 can be ensured. .

  In the present embodiment described here, the nip roller 170 is provided on the upstream side and the downstream side in the paper conveyance direction with respect to the nip plate 130, but the nip roller 170 may be provided on either the upstream side or the downstream side of the nip plate 130. Only one crab may be provided. In this case, it is desirable that the nip roller 170 is provided only on the downstream side of the nip plate 130 in the paper transport direction. This makes it easier for the paper P to enter the nip portion than when the nip roller 170 is provided on the upstream side.

[Second Embodiment]
Next, a second embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the present embodiment, the guide member supports the nip roller via a bearing. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 7, the nip roller 270 according to the second embodiment is rotatably supported by a bearing 271 at positions corresponding to both ends of the fixing film 110. The bearing 271 is supported by the guide member 280.

  Specifically, a hole 281 that extends upward is formed in the guide member 280 on the surface facing the nip roller 270, and the bearing 271 is engaged with the hole 281. A compression spring 290 as an example of a second urging unit is disposed between the bottom surface of the hole 281 and the bearing 271. The compression spring 290 always urges the bearing 271 downward. That is, the guide member 280 supports the bearing 271 so as to be movable in the vertical direction (opposite direction of the pressure roller 150 and the nip plate 130), and urges the nip roller 270 toward the pressure roller 150 by the compression spring 290. is doing.

  A protrusion 282 is formed at the lower end of the hole 281. On the other hand, a locking portion 272 is provided at the upper end of the bearing 271. When the pressure roller 150 is pulled away from the nip roller 270 due to jamming or the like, the bearing 271 (nip roller 270) is locked by the locking portion 272 hitting the protrusion 282, and the nip roller 270 is not detached from the guide member 280. The nip roller 270 does not pull the fixing film 110 down too much.

  The nip roller 270 is in pressure contact with the inside of the fixing film 110 on the inner side in the left-right direction than the bearing 271 and is in pressure contact with the outer periphery of the pressure roller 150 on the outer side in the left-right direction. Accordingly, when the pressure roller 150 is rotationally driven, the nip roller 270 receives the driving force of the pressure roller 150 and is driven to rotate to apply the driving force to the fixing film 110.

According to the above, even when the guide member 280 supports the bearing 270 as in the present embodiment, the same effects as those of the first embodiment can be obtained.
Unlike the first embodiment, the fixing device 100 of the present embodiment does not connect (pull) the pressure roller 150 and the nip roller 270 to each other by a spring. When the pressure roller 150 is pulled away from the nip roller 270, the nip roller 270 does not pull the fixing film 110 down too much, so that jamming can be easily performed and damage to the fixing film 110 can be suppressed.

  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 embodiment, the plate-shaped nip plate 130 is exemplified as the nip member. However, the present invention is not limited to this, and for example, a thick member that is not plate-shaped may be employed.

  Moreover, in the said embodiment, although the nip member and the heat generating body were used as separate parts, this invention is not limited to this. For example, a plate-shaped ceramic heater may be employed as a member that serves as both a nip member and a heating element.

  In the embodiment, the pressure roller 150 is exemplified as the backup member. However, the present invention is not limited to this, and may be, for example, a belt-like pressure member.

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

  In the embodiment, the laser printer 1 is exemplified as the image forming apparatus including the fixing device 100 of the present invention. However, the present invention is not limited to this, and may be, for example, an LED printer that performs exposure using LEDs. However, it may be a copier or multifunction machine other than a printer. 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 1 Laser printer 100 Fixing device 110 Fixing film 120 Halogen lamp 130 Nip plate 140 Reflecting plate 150 Pressure roller 160 Stay 170 Nip roller 180 Guide member 190 Tension spring 270 Nip roller 280 Guide member 290 Spring P Paper

Claims (8)

A tubular member having flexibility;
A nip member disposed so as to be in sliding contact with the inner surface of the tubular member;
A back-up member that is supplied with driving force and forms a nip region with the nip member via the cylindrical member, and a fixing device comprising:
A fixing device comprising: a roller that is in pressure contact with both the inside of the cylindrical member and the backup member, and that is driven to rotate by receiving a driving force of the backup member.   First biasing means for generating a biasing force between the backup member and the nip member and the first biasing means for biasing the roller toward the backup member are provided separately. The fixing device according to claim 1, further comprising a second urging unit.   The fixing device according to claim 2, wherein the backup member and the roller are attracted to each other by the second urging unit. A guide member for regulating the end face of the tubular member;
The fixing device according to claim 1, wherein the roller protrudes outside the guide member. A bearing for rotatably supporting the roller;
The fixing device according to claim 4, wherein the bearing is supported by the guide member.   The fixing device according to claim 5, wherein the guide member supports the bearing so as to be movable in a facing direction of the backup member and the nip member.   The fixing device according to claim 1, wherein the roller is provided only on a downstream side of the nip member in a recording sheet conveyance direction.   7. The fixing device according to claim 1, wherein the roller is provided on an upstream side and a downstream side in the recording sheet conveyance direction with respect to the nip member. 8.

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