JP2010217431A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of efficiently heating papers (recording sheets). <P>SOLUTION: The fixing device is provided with: a heat source (halogen lamp 110), which emits radiation to the recording sheet (paper 3) to heat the recording sheet; a bag body 120, which transmits radiation and in the inside of which a space is held; and a pressure roller 42 which conveys the recording sheet by rotating while holding the recording sheet between it and the bag body 120. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing device that thermally fixes toner on a sheet with radiant heat.

  2. Description of the Related Art Conventionally, a fixing device having a transparent cylindrical glass tube configured to be rotatable, a heat source disposed in the glass tube, and a pressure roller that is pressed by the glass tube and rotates together with the glass tube is known. (See Patent Document 1). In this technique, the radiation image emitted from the heat source passes through the glass tube, so that the toner image on the paper is favorably heated by the radiant heat.

JP-A-55-87178

  However, in the prior art, when the glass tube rotates, the heat of the paper heated by the radiant heat is taken away by a part of the glass tube, and then this part moves and is cooled by the external air. As a result, when a part of the cooled glass tube moves again to the nip position between the glass tube and the pressure roller, a large amount of heat is taken from the paper, and the paper cannot be heated efficiently. There was a problem.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of efficiently heating a sheet (recording sheet).

  The present invention that solves the above-described problems includes a heat source that emits radiation to the recording sheet and heats the recording sheet, a bag that transmits the radiation and that has a space therein, and the bag. And a pressure roller that conveys the recording sheet by rotating with the recording sheet sandwiched therebetween.

  Here, “a space is maintained inside” means a state in which the space is confined in the bag.

  According to the present invention, the radiation emitted from the heat source passes through the bag or space to reach the recording sheet, and heats the recording sheet with radiant heat. At this time, since the heat of the recording sheet is hardly transmitted to the space held in the bag, the recording sheet can be efficiently heated.

  According to the present invention, since the heat of the recording sheet heated by radiant heat is difficult to be transmitted to the space held in the bag, the recording sheet can be efficiently heated.

1 is a cross-sectional view illustrating a laser printer including a fixing device according to an embodiment of the present invention. It is sectional drawing which shows the detail of a heating body. They are the expanded sectional view (a) which shows the form which provided the infrared rays absorption layer in the permeation | transmission film, and the enlarged sectional view (b) which shows the form which provided the infrared rays absorption layer in the bag. It is sectional drawing (a) which shows the form which rotated the bag body, and sectional drawing (b) which shows the form which provided the infrared rays absorption layer in the bag body of Fig.4 (a). They are sectional drawing (a) which shows the form which provides a bag body around a cylindrical member, a transverse sectional view (b), and an expanded sectional view (c) which shows the mechanism which adjusts the pressure in a bag body. It is sectional drawing (a) which shows the modification of a pressure adjustment mechanism, and a cross-sectional view (b). It is sectional drawing which shows the form which used the 2nd bag body as a pressure roller.

<Overall configuration of laser printer>
Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the laser printer 1 includes a feeder unit 4 for feeding a sheet 3 as an example of a recording sheet in an apparatus main body 2 and an image for forming an image on the fed sheet 3. The formation part 5 etc. are provided.

  The feeder unit 4 mainly includes a paper feed tray 6 that is detachably attached to the bottom of the apparatus main body 2 and a paper supply mechanism 7 that transports the paper 3 from the paper feed tray 6 to the image forming unit 5. In the feeder unit 4, the sheets 3 in the sheet feeding tray 6 are separated one by one by the sheet supply mechanism 7 and supplied to the image forming unit 5.

  The image forming unit 5 includes a scanner unit 16, a process cartridge 17, a fixing device 18, and the like.

  The scanner unit 16 is provided in the upper part of the apparatus main body 2 and includes a laser light emitting unit (not shown), a polygon mirror 19 that is rotationally driven, lenses 20, 21 and reflecting mirrors 22, 23, 24, and the like. . In the scanner unit 16, the laser beam is irradiated on the surface of the photosensitive drum 27 of the process cartridge 17 by high-speed scanning through a path indicated by a chain line in the drawing.

  The process cartridge 17 is disposed below the scanner unit 16 and is configured to be detachably attached to the apparatus main body 2. The process cartridge 17 includes a known photosensitive drum 27, a charger 29, a transfer roller 30, a developing roller 31, a layer thickness regulating blade 32, a supply roller 33, a toner hopper 34, and the like.

  In the process cartridge 17, the surface of the photosensitive drum 27 charged by the charger 29 is exposed with a laser beam from the scanner unit 16, whereby an electrostatic latent image is formed on the photosensitive drum 27. A toner image (developer image) is formed on the photosensitive drum 27 by supplying toner in the toner hopper 34 to the electrostatic latent image via the supply roller 33 and the developing roller 31. Thereafter, when the sheet 3 is conveyed between the photosensitive drum 27 and the transfer roller 30, the toner image on the photosensitive drum 27 is transferred to the sheet 3.

<Configuration of fixing device>
The fixing device 18 mainly includes a heating body 100 that heats the paper 3 and a pressure roller 42 that conveys the paper 3 by sandwiching and rotating the paper 3 between the heating body 100. The pressure roller 42 is formed by providing silicon rubber around the core metal and covering the surface of the silicon rubber with a PTFE tube. The details of the heating body 100 will be described later.

  In the fixing device 18 configured as described above, the toner image transferred onto the paper 3 is heated by the heating body 100 while the paper 3 passes between the heating body 100 and the pressure roller 42. Is heat-fixed. Thereafter, the sheet 3 is transported to the paper discharge path 44 by the transport roller 43. The paper 3 sent to the paper discharge path 44 is discharged onto a paper discharge tray 46 by a paper discharge roller 45.

<Structure of heating element>
Next, the structure of the heating body 100 will be described in detail.
As shown in FIG. 2, the heating body 100 mainly includes a halogen lamp 110 as an example of a heat source, a bag body 120, and a transmission film 130.

  The halogen lamp 110 is a heat source that emits infrared rays (radiation rays). The emitted infrared rays are reflected directly or by the reflector 111 and directed toward the nip portion (clamping portion) between the pressure roller 42 and the bag body 120. Released. As a result, the sheet 3 sandwiched between the pressure roller 42 and the bag body 120 is heated by radiant heat.

  The bag body 120 is formed in a closed bag shape by a thin film-like sheet that transmits infrared rays (radiation rays) and is elastically deformable, and a closed space is held therein. Specifically, the bag body 120 is filled with compressed air as an example of compressed gas, and the upper portion thereof is fixed to the frame 18 </ b> A of the fixing device 18. As a result, the bag body 120 supported by the frame 18A is pressurized toward the pressure roller 42 by the internal compressed air, and a desired nip pressure is obtained.

  Here, the thickness of the thin film sheet is desirably set to 100 μm or less. In addition, as a material for the thin film sheet, for example, Silplus (registered trademark) manufactured by Nippon Steel Chemical Co., Ltd., Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd., or the like can be employed.

  The transmission film 130 is formed in a cylindrical shape that surrounds the bag body 120 with a material that transmits infrared rays (radiation rays), and a part of the transmission film 130 is disposed between the bag body 120 and the pressure roller 42. The transmission film 130 can be driven to rotate following the rotation of the pressure roller 42 when the pressure roller 42 is rotated by a driving source (not shown).

  Here, the thickness of the transmission film 130 is desirably set to 100 μm or less. Moreover, as a material of the transmissive film 130, for example, Sylplus (registered trademark) or Neoprim (registered trademark) can be employed.

<Operation of heating element>
Next, the operation of the heating body 100 will be described.
When the sheet 3 is sandwiched between the heating body 100 and the pressure roller 42, the infrared rays emitted from the halogen lamp 110 reach the sandwiched portion through the bag body 120 and the transmission film 130. Thereby, the paper 3 and the toner on the paper 3 are heated by radiant heat. At this time, since the heat of the paper 3 is hardly transmitted to the space held in the bag body 120, the paper 3 can be heated efficiently.

According to the above, in addition to the effects described above, the following effects can be obtained in the present embodiment.
Since the bag body 120 is formed of a thin sheet, the volume of the bag body 120 itself is small and the heat capacity is small, so that the heat transmitted from the paper 3 to the bag body 120 itself through the transmission film 130 can be reduced. Further, since the volume of the transmission film 130 is small and the heat capacity is small, the heat transferred from the paper 3 to the transmission film 130 can also be reduced. Thereby, the amount of heat taken away from the paper 3 by the transmissive film 130 and the bag body 120 is reduced, and the paper 3 can be heated more efficiently.

  Since the bag body 120 is formed of an elastically deformable thin-film sheet and compressed air is enclosed therein, the sheet 3 can be evenly pressurized by the bag body 120.

  Since the transparent film 130 that rotates following the rotation of the pressure roller 42 is provided around the bag body 120, it is possible to suppress the jamming of the paper 3 in the fixed bag 120, and the paper 3 is transported satisfactorily. be able to.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the said embodiment, although the bag body 120 and the whole transmission film 130 were formed with the material which can permeate | transmit infrared rays, this invention is not limited to this. For example, as shown in FIG. 3A, an infrared absorption layer 131 that absorbs infrared rays may be provided on the outer peripheral surface of the transmission film 130, or as shown in FIG. The infrared absorption layer 121 may be provided on the third side (specifically, the nip portion with the pressure roller 42).

  According to this, even when toner other than black is fixed, infrared rays are absorbed by the infrared absorption layers 131 and 121 without being reflected by the toner. Therefore, the color toner can be satisfactorily heated and fixed by heat conduction from the high-temperature infrared absorption layers 131 and 121 that absorb infrared rays.

  In the embodiment, the bag body 120 is fixed to the frame 18A of the fixing device 18, but the present invention is not limited to this. For example, as shown in FIG. 4A, the bag body 220 formed in a hollow cylindrical shape may be configured to be rotatable in accordance with the rotation of the pressure roller 42.

  Specifically, in this structure, the hollow cylindrical bag body 220 is supported so as to be sandwiched between the pressure roller 42 and the pair of rotation rollers R1 and R2 so as to be driven by the rotation of the pressure roller 42. It is configured. Further, the halogen lamp 110 and the reflection plate 111 may be disposed on the side opposite to the pressure roller 42 with the bag body 220 interposed therebetween. Even in this structure, the paper 3 is suppressed from being jammed by the bag body 220, and the paper 3 can be transported satisfactorily.

  Also in this structure, as shown in FIG. 4B, an infrared absorption layer 221 may be provided on the outer peripheral surface of the bag body 220. Also in this case, as described above, the color toner can be thermally fixed satisfactorily.

  In the above embodiment, the compressed air is simply enclosed in the bag body 120. However, the present invention is not limited to this, and a structure in which the pressure in the bag body 120 is always constant may be adopted. . As such a structure, for example, the structure shown in FIGS. 5 and 6 can be adopted. Specifically, in the structure shown in FIGS. 5A to 5C, the cylindrical tubular member 310, the bag 320 fixed to the outer peripheral surface 311 of the tubular member 310, and the tubular member 310 are rotated. It is configured to include a support portion 330 that supports it.

  The cylindrical member 310 is formed of a material such as alumina silicate glass that transmits infrared rays (radiation rays) from the halogen lamp 110. A part of the peripheral wall of the cylindrical member 310 includes the inside of the cylindrical member 310 (specifically, in a closed space formed by the cylindrical member 310 and the support portion 330) and the inside of the bag body 320 (specifically, the bag body). A communication hole 312 is formed to communicate between 320 and the cylindrical member 310 in a closed space.

  A gear 313 is fixed to one end of the cylindrical member 310 so as to rotate integrally. The gear 313 is driven by a driving source such as a motor (not shown) directly or via at least one gear G. Is transmitted. Thereby, the cylindrical member 310 rotates with respect to the support part 330.

  The bag body 320 is fixed to the outer peripheral surface 311 so as to surround the outer peripheral surface 311 of the cylindrical member 310 in the circumferential direction.

  The support part 330 is a part formed in the frame of the fixing device 18, and mainly includes an end support part 331 that rotatably supports one end side of the cylindrical member 310, and the other end side of the cylindrical member 310. The other end support part 332 supported so that it is possible, and the connection part 333 which connects the one end support part 331 and the other end support part 332 are provided.

  The connecting portion 333 is formed at a position away from the inner surface of the cylindrical member 310. Thereby, the communication hole 312 formed in the cylindrical member 310 communicates with a closed space formed by the inner surface of the cylindrical member 310, the inner surface of the one end support portion 331, and the inner surface of the other end support portion 332. . In addition, the reflection plate 111 is fixed to the connecting portion 333. The halogen lamp 110 is fixed to the support portion 330 via a bracket (not shown).

  An elongated bottomed cylindrical first pipe 341 is attached to the other end support portion 332 so as to penetrate in the axial direction of the cylindrical member 310. Specifically, the opening of the first pipe 341 is disposed in the tubular member 310, and the bottom surface is disposed outside the tubular member 310. The bottom surface of the second pipe 342 having a long bottomed cylindrical shape is fixed to the bottom surface of the first pipe 341.

  The first pipe 341 and the second pipe 342 are formed with an intake hole H1 and an exhaust hole H2 communicating with each other. An inlet valve 343 that closes the intake hole H1 by being biased by the first coil spring S1 is provided in the first pipe 341, and is biased by the second coil spring S2 in the second pipe 342. An outlet valve 344 that closes the exhaust hole H2 is provided.

  A pump (not shown) is connected to the opening of the second pipe 342. As a result, when the pressure in the second pipe 342 exceeds the pressure obtained by adding the pressure in the first pipe 341 and the pressure by the first coil spring S1, the inlet valve 343 opens and the pressure in the first pipe 341 is increased. As a result, the inside of the bag body 320 is pressurized. When the pressure in the bag body 320, that is, in the first pipe 341 exceeds the pressure obtained by adding the pressure in the second pipe 342 and the pressure by the second coil spring S2, the outlet valve 344 opens. The inside of the bag body 320 is depressurized.

  That is, when the pressure in the bag body 320 becomes a predetermined value or more, the outlet valve 344 is opened and the gas in the bag body 320 is released to the outside (in the second pipe 342). Moreover, when the pressure in the bag body 320 becomes less than a predetermined value, the inlet valve 343 is opened and gas is taken into the bag body 320 from the outside (inside the second pipe 342).

  As described above, according to this embodiment, since the pressure in the bag body 320 can be kept constant, the sheet 3 can be favorably sandwiched and transported between the bag body 320 and the pressure roller 42. Moreover, even if the inside of the bag body 320 is heated by the heat from the heated paper 3 and the pressure is increased, the internal compressed air can be appropriately removed from the outlet valve 344, so that the nip pressure has a good value. Can be maintained.

  Note that the pressure adjusting mechanism including the first pipe 341, the second pipe 342, the inlet valve 343, the outlet valve 344 and the like shown in FIG. 5 is, for example, a pressure inside the non-rotating bag 120 as shown in FIG. It can also be applied for adjustment.

  Moreover, the structure shown to Fig.6 (a), (b) is mainly provided with the cylindrical member 410 different from the form of FIG. Here, the bag body 320, the support portion 330, and the like having the same structure as that of the embodiment of FIG.

  The cylindrical member 410 is formed in a bottomed cylindrical shape with a material that transmits infrared rays (radiation rays), and the opening side of the cylindrical member 410 is rotatably fitted to one end support portion 331 of the support portion 330. On the bottom surface side of the tubular member 410, there are a piston 500 that is slidably in contact with the inner peripheral surface of the tubular member 410 and can advance and retreat in the axial direction, and a biasing member that biases the piston 500 toward the other end support portion 332. As an example, a coil spring 501 is provided.

  Further, between the piston 500 and the other end support portion 332 of the tubular member 410, the inside of the tubular member 410 (specifically, the closed formed by the tubular member 410, the other end support portion 332 and the piston 500). A communication hole 412 that communicates between the interior of the bag body 320 and the interior of the bag body 320 (specifically, the closed space formed by the bag body 320 and the tubular member 410). The other end support portion 332 disposed closer to the opening end side (one end side) of the tubular member 410 than the communication hole 412 allows the gas flow that moves from the communication hole 412 to the opening end side of the tubular member 410. It functions as a regulatory barrier to stop.

  Even in this structure, the pressure in the bag body 320 can be kept constant at a pressure corresponding to the urging force of the coil spring 501, so that the same effect as that of the embodiment of FIG.

  In the above embodiment, the pressure roller 42 is formed in a solid shape with silicon rubber or the like, but the present invention is not limited to this. For example, as shown in FIG. 7, the second bag body 520 holding a space therein is provided. You may employ | adopt as a pressure roller. Specifically, the second bag body 520 is formed in a hollow columnar shape, and is supported so as to be sandwiched from three directions by a bag body 320 similar to the form of FIG. 5 and a pair of rotating rollers R3 and R4. Yes.

  The second bag body 520 is configured to follow and rotate following the rotating bag body 320. According to this, the heat of the paper 3 heated and raised by the radiant heat is not easily transmitted to the second bag body 520 as the pressure roller, so that the paper 3 can be heated more efficiently.

  In the above embodiment, the compressed air is enclosed in the bag body 120. However, the present invention is not limited to this, and other compressed gas may be used, or the hollow cylindrical glass with a thin bag body. When formed with a tube, it may be a vacuum. In particular, it is desirable to use argon gas having a low thermal conductivity.

  In the form of FIG. 2, the transmission film 130 is provided. However, the present invention is not limited to this, and the pressure roller may be slidably brought into contact with the non-rotating bag body without providing the transmission film. Good.

In the embodiment, the halogen heater HH is employed as an example of the heat source. However, the present invention is not limited to this, and for example, an induction heating type IH (Induction Heating) heater or a heating resistor may be employed.
In the embodiment, the paper 3 such as a thick paper, a postcard, and a thin paper is used as an example of the recording sheet. However, the present invention is not limited to this, and may be an OHP sheet, for example.

  In the embodiment, the radiation is emitted toward the nip portion. However, the present invention is not limited to this, and the toner may be emitted toward the portion of the paper before the nip passes.

3 Paper 18 Fixing device 18A Frame 42 Pressure roller 100 Heating body 110 Halogen lamp 111 Reflecting plate 120 Bag body 130 Transmission film

Claims (11)

A heat source that emits radiation to the recording sheet to heat the recording sheet;
A bag body that transmits the radiation and has a space therein;
A fixing device, comprising: a pressure roller that conveys the recording sheet by rotating the recording sheet sandwiched between the bag body.   The fixing device according to claim 1, wherein the bag is formed of a thin film sheet. The thin film sheet is elastically deformable,
The fixing device according to claim 2, wherein a compressed gas is sealed in the bag body.   The fixing device according to claim 1, wherein the bag body is fixed to a frame of the fixing device. A transmission film that transmits the radiation and is formed in a cylindrical shape surrounding the bag body, and a part of the transmission film is disposed between the bag body and the pressure roller;
The fixing device according to claim 4, wherein the transmissive film is rotatable in accordance with the rotation of the pressure roller. The heat source is configured to emit infrared rays as the radiation;
The fixing device according to claim 5, wherein an infrared absorption layer is provided on the recording sheet side of the bag or the transmission film.   The fixing device according to claim 1, wherein the bag body is rotatable in accordance with rotation of the pressure roller. The heat source is configured to emit infrared rays as the radiation;
The fixing device according to claim 7, wherein an infrared absorption layer is provided on the bag body. An outlet valve that opens when the pressure in the bag becomes equal to or greater than a predetermined value and releases the gas in the bag to the outside;
The inlet valve which opens when the pressure in the said bag body becomes less than the said predetermined value, and takes in gas into the said bag body from the outside is provided, The any one of Claims 1-8 characterized by the above-mentioned. Fixing device. A cylindrical member that transmits the radiation;
The bag body is fixed to the outer peripheral surface so as to surround the outer peripheral surface of the cylindrical member in the circumferential direction,
In the tubular member,
A communication hole communicating the inside of the cylindrical member and the bag body;
A regulating wall that is disposed on one end side of the cylindrical member from the communication hole and stops the flow of gas that moves from the communication hole to one end side of the cylindrical member;
A piston which is provided on the opposite side of the restriction wall from the communication hole, and which is slidable in contact with the inner surface of the cylindrical member and capable of moving back and forth in the axial direction;
The fixing device according to claim 7, further comprising an urging member that urges the piston toward the restriction wall. 11. The fixing device according to claim 1, wherein the pressure roller is a second bag body that holds a space therein.

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