JP2008139382A - Fixing device, and image forming apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device by which a stable fixability can be secured, a warm-up time is shortened, the convenience of a user is improved and electric power consumption is saved. <P>SOLUTION: In the fixing device 1 provided with an endless, belt-like thin heating member 72; each radiation heating source 77 arranged in the heating member 72; a pressurizing member 73 press-welded with the heating member 72 so as to form a nip part N for passing a sheet and heating/pressurizing the same, and rotatively drives; a pressure-receiving member 74 provided at the inside of the heating member 72 so as to contact with the heating member 72 for receiving the pressure from the pressurizing member 73 in the nip part N; and a reinforcing member 76 planted in the pressure receiving member 74, a part of each radiation heating source 77 is provided with a reflecting film 81 or a reflecting member 83, in such a manner that radiation light does not directly strike the heating member 72 from each radiation heating source 77, and the reinforcing member 76 is provided with a reflecting film 80 or a reflecting member 82 for reflecting the radiation light from each radiation heating source 77. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and an image forming apparatus including the same.

  In general, in an electrophotographic image forming apparatus such as a copying machine, a fixing device is used as means for heating and pressurizing a toner image formed on a sheet by the image forming apparatus to melt the toner and fix the toner image on the sheet. In general, the fixing device heats and presses the sheet on which the toner image has been transferred to fix the toner image on the sheet, and is thus brought into pressure contact with a heating roller that is heated to a temperature at which the toner can be melted. A pressure roller, and a nip is formed by the heating roller and the pressure roller. The sheet onto which the toner image has been transferred enters the nip, and the sheet is conveyed while being sandwiched between the nip, whereby the toner image is fixed to the sheet.

  The fixing device usually has a heat source for heating the heating roller. Here, if the heating roller, that is, the fixing device can be rapidly warmed to a temperature capable of melting the toner, the waiting time of the user after the image forming apparatus is turned on or after returning from the sleep mode can be reduced. , User convenience is improved. In addition, it is possible to supply power to the heat source only when the image forming apparatus is used, and to lower the temperature of the fixing device when not in use as compared with the conventional one, thereby reducing the power consumption of the image forming apparatus. it can.

Therefore, Patent Document 1 describes a configuration for rapidly warming the fixing device. In Patent Document 1, in a heat roller type toner fixing device having a heating roller with a built-in heater and a pressure roller, a heat ray reflecting plate is provided in the heating roller, and the heat ray reflecting plate has not yet determined infrared rays from the heater. There has been proposed a heat roller type fixing device which is equipped to irradiate a fixing heating and pressing part region on the inner surface of the heating roller on the side in contact with the contacted toner. By configuring in this way, attempts have been made to achieve rapid temperature rise and power saving of the heating roller. (See Patent Document 1: Claim 1, FIG. 1, paragraph 0031).
JP 08-160794 A

  Here, in order to warm up the fixing device more rapidly, the fixing device is not a heating roller, but an endless belt-like heating member formed much thinner than the heating roller, and radiation provided inside the heating member. A heat generation source, a pressure member that presses against the heating member to form a nip, and a pressure receiving member that is provided in contact with the endless belt inside the heating member of the nip portion that receives the pressure of the pressure member because the heating member is thin May be configured. In such a fixing device, the pressure member is rotationally driven, and the heating member is driven.

  The endless belt-shaped heating member is made of, for example, a metal film, a metal foil, or the like, is thin, and specifically has a sleeve shape or a cylindrical shape. Since the heating member is thin, even if a radiation heat source with a lower output than before is used, the heating member is quickly heated by the heat source, and the warm-up time until the toner can be melted and fixed can be extremely shortened. Can achieve power saving. In this fixing device, the sheet onto which the toner image has been transferred enters the nip formed by the heating member, the pressure member, and the pressure receiving member, and is conveyed while being sandwiched between the nips. It is pressurized and melted and fixed to the sheet.

  However, when a thin member is used as a heating member for heating the sheet, there is a problem that temperature unevenness may occur on the surface of the heating member although it can be quickly heated. This is one of the reasons that radiation light is not emitted uniformly from the surface of the radiation heat source. For example, in a radiation heat source such as a halogen lamp, the filament is usually a winding, and the emitted radiation is uneven. In particular, the temperature unevenness that appears on the outer surface of the heating member becomes more prominent as the radiant heat source and the heating member are closer.

  Further, since the heating member is thin, the radiant heat generated by the radiant light absorbed by the inner surface of the heating member is not uniformized while being transmitted from the inner surface of the heating member to the outer surface. In other words, as long as the heating roller described in Patent Document 1 has a certain thickness (see Patent Document 1: Paragraph 0018) and has a certain heat capacity with respect to the heat generation source, it is transmitted from the inner surface of the heating member to the surface. In the meantime, the temperature unevenness is alleviated and uniformed, but if it is thin, it will appear as temperature unevenness on the surface of the heating member as it is.

  Such temperature unevenness on the outer surface of the heating member is more specifically, because the radiation heat source is provided inside along the longitudinal direction of the thin endless belt, the direction perpendicular to the sheet conveying direction. Appears as temperature unevenness in

  Since fixing cannot be performed reliably until the temperature rises to the fixable temperature even in the low temperature part, as a result, the temperature unevenness hinders the temperature rise of the entire fixing device and causes the warm-up time to become longer. Become. Further, if fixing is performed with the temperature unevenness on the surface of the heating member, a fixing failure may be caused due to a low temperature portion. Therefore, the temperature unevenness causes a fixing failure.

  Therefore, looking at the invention described in Patent Document 1, due to its configuration, a radiation heat source is actively brought close to the heating roller, and radiation light is applied to the heating roller (Patent Document 1: FIG. 1, paragraph). 0019). If a thin heating member is applied instead of the heating roller, temperature unevenness may occur on the outer surface of the heating member for the above reasons. Therefore, the invention described in Patent Document 1 cannot be applied to a fixing device using a thin heating member. Although the heat ray reflector is provided in the invention described in Patent Document 1, it is not provided in consideration of temperature unevenness, and the radiation heat source and the heating roller are arranged close to each other. It doesn't come to be solved.

  If it does so, invention of patent document 1 cannot be applied to the fixing apparatus using thin-walled, for example, a film-like heating member, Warm-up time will become long or a fixing defect will arise. Actually, Patent Document 1 does not describe temperature unevenness on the surface of the heating roller. In addition, the cylindrical member which is 0.5-1 mm is used for the heating roller of patent document 1 (patent document 1: Paragraph 0018), and it has a fixed thickness and a heat capacity, Description about temperature nonuniformity There is no.

  The present invention has been made in view of the above-described problems of the prior art, and provides a fixing device that can ensure stable fixing performance, shorten warm-up time, improve user convenience, and achieve power saving. For the purpose. Another object of the present invention is to provide a power-saving image forming apparatus that is highly convenient for the user, has no poor fixing, and has good image quality.

  In order to achieve the above object, the invention according to claim 1 forms an endless belt-like heating member, a radiant heat source disposed in the heating member, and a nip for heating and pressurizing the sheet through it. A pressure member that is in pressure contact with the heating member and rotationally driven, a pressure receiving member provided in contact with the heating member inside the heating member to receive pressure from the pressure member in the nip, In a fixing device including a reinforcing member that is pushed against the pressure receiving member, a reflection film or a reflection member is provided on a part of the radiation heat source so that radiation light does not directly strike the heating member from the radiation heat source. The reinforcing member is provided with a reflecting film or a reflecting member for reflecting radiation light from the radiation heat source.

  According to a second aspect of the present invention, in the first aspect of the present invention, the reinforcing member is formed to have an inclined surface for diffusing radiant light with respect to a direction thrust against the pressure receiving member. It was.

  According to a third aspect of the present invention, in the first or second aspect of the invention, aluminum is used for the reflective film and the reflective member.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising the fixing device according to any one of the first to third aspects.

  According to the first aspect of the present invention, the radiation light from the radiation heat source is not directly applied to the heating member, but the reflection light or the reflection member is provided on the radiation heat source or the reinforcing member so that the radiation light is reflected and diffused to some extent. Since the radiant light is applied to the inner surface of the heating member after being in a state of being made, for example, even when a heating member of a film-like endless belt is used, it is possible to prevent the occurrence of temperature unevenness on the outer surface of the heating member. it can. Therefore, since the heating member can be uniformly and rapidly heated, it is easily achieved to keep the heating member at the temperature required for fixing even if continuous fixing is performed, and the temperature on the outer surface of the heating member is easily achieved. It can prevent that a low part and a high part are made, and can secure a stable fixing property. In addition, it is not necessary to wait for the temperature of the low temperature portion to avoid fixing failure, and the warm-up time for warming the heating member can be shortened.

  Furthermore, since the heating member is formed thinner than a conventional heating roller and can quickly warm the heating member, the warm-up time can be extremely shortened in this respect as well. Rise. Further, since it is not necessary to preheat the heating member, power saving can be achieved.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, since the reinforcing member is formed to have an inclined surface, the reflection surface has an angle so that the radiation heat is emitted to the radiation heat source. Therefore, the heating member can be warmed efficiently. That is, the warm-up time can be further shortened and stable fixing properties can be secured.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, it is possible to provide a fixing device that is advantageous in terms of cost.

  According to the invention described in claim 4, since the fixing device according to any one of claims 1 to 3 is used, the warm-up time is extremely short, the fixing property is stable, and the convenience for the user is high. Therefore, it is possible to provide a high-quality image forming apparatus that saves power.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. However, each element such as configuration and arrangement described in this embodiment does not limit the scope of the invention and is merely an illustrative example.

  First, an outline of an electrophotographic full-color image forming apparatus 2 provided with a fixing device 1 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view seen from the front showing the schematic configuration of the image forming apparatus 2 according to the first embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus 2 includes a case 2a having a box shape. The case 2a includes an image forming unit 10, an intermediate transfer unit 20, a secondary transfer unit 30, a sheet supply unit 40, a sheet conveyance path 50, a fixing device 1, a discharge unit 60, and the like.

  The image forming unit 10 is for forming a toner image based on the image data input to the image forming apparatus 2. The image forming unit 10 is provided so as to be positioned above the inside of the image forming apparatus 2. As shown in FIG. 1, the image forming unit 10 includes an image forming unit 10B that forms a black image, an image forming unit 10Y that forms a yellow image, an image forming unit 10C that forms a cyan image, and a magenta image. Image forming units 10B, 10Y, 10C, and 10M are provided. Thereby, the image forming apparatus 2 can perform full-color image formation.

  The four image forming units 10B, 10Y, 10C, and 10M are sequentially arranged in the order of 10B (black), 10Y (yellow), 10C (cyan), and 10M (magenta) from the left side to the right side in FIG. Is done. Since the image forming units 10B, 10Y, 10C, and 10M have the same configuration, the image forming unit 10 is omitted from the reference numerals B, Y, C, and M, and the image forming unit 10 is described below. Unify unless otherwise stated. Accordingly, the image forming units 10B, 10Y, 10C, and 10M can be described in the same manner.

  As shown in FIG. 1, the image forming unit 10 includes a photosensitive drum 11 as an image carrier, a charging roller 12, an exposure device 13, a developing device 14, a primary transfer roller 15, a drum cleaning roller 16, and the like. ing.

  The photosensitive drum 11 is for forming a toner image by supplying toner T after an electrostatic latent image is formed on the peripheral surface thereof. The photosensitive drum 11 is disposed at the center position of the image forming unit 10. For example, the photosensitive drum 11 is configured to have a positively charged OPC or amorphous silicon photosensitive layer on the outer peripheral surface of an aluminum drum, and is driven at a predetermined process speed by a driving device (not shown). Is rotated counterclockwise when viewed from the front.

  The charging roller 12 is for charging the peripheral surface of the photosensitive drum 11 with a predetermined potential. Therefore, a predetermined voltage is applied to the charging roller 12. The charging roller 12 is disposed above the photosensitive drum 11 in FIG. 1 and rotates in a clockwise direction in front view in FIG. 1 at a predetermined process speed.

  The exposure device 13 applies laser light to the photosensitive drum 11 on the peripheral surface of the photosensitive drum 11 uniformly charged by the charging roller 12 based on the image data to be formed input to the image forming device 2. This is for irradiating and scanning and exposing the peripheral surface of the photosensitive drum 11. As a result, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 11. In FIG. 1, the exposure device 13 is disposed above the photosensitive drum 11 and on the left side of the charging roller 12.

  The developing device 14 supplies toner T toward the electrostatic latent image formed on the peripheral surface of the photosensitive drum 11. By supplying toner T from the developing device 14 to the electrostatic latent image on the photosensitive drum 11, a toner image is formed on the peripheral surface of the photosensitive drum 11. The developing device 14 is provided on the left side of the photosensitive drum 11 in FIG. 1, and a developing roller 14a is provided at a position facing the photosensitive drum 11 while providing a predetermined gap. Further, the developing roller 14a rotates in a clockwise or counterclockwise direction in FIG. 1 at a predetermined process speed.

  The developing device 14 stores the developer containing the toner T and charges the toner to a predetermined potential (note that the developing device 14 of the image forming unit 10B applies the developer containing the black toner T to the image forming unit. The developing device 14 of 10Y includes a developer containing yellow toner T, the developing device 14 of the image forming unit 10C includes a developer including cyan toner T, and the developing device 14 of the image forming unit 10M includes magenta toner T. Contains developer). The developer is accommodated in the developing device 14 above the developing roller 14a. The toner supply roller 14b disposed obliquely above the developing roller 14a applies an appropriate amount of toner T (developer) to the developing roller so that a thin layer of toner T is formed on the peripheral surface of the developing roller 14a. 14a for supply.

  The primary transfer roller 15 is for transferring a toner image formed on the photosensitive drum 11 to an intermediate transfer belt 24 stretched in an intermediate transfer unit 20 described later. The primary transfer roller 15 is disposed below the photosensitive drum 11 and abuts with the photosensitive drum 11 via an endless intermediate transfer belt 24 to form a nip for primary transfer. A predetermined voltage is applied to the primary transfer roller 15 for transferring the toner image. Further, the primary transfer roller 15 is driven by the photosensitive drum 11 and the intermediate transfer belt 24 in FIG. 1 and rotates counterclockwise when viewed from the front in FIG.

  The drum cleaning roller 16 is for removing and collecting the primary transfer residual toner T remaining on the surface of the photosensitive drum 11 so that a toner image to be formed next is appropriately formed. Is for. For example, the drum cleaning roller 16 has a peripheral surface made of a material such as EPDM, is formed in a cylindrical shape, and is driven to rotate counterclockwise in a front view of FIG. 1 at a predetermined process speed.

  Next, the intermediate transfer unit 20 will be described. The intermediate transfer unit 20 is for transferring a toner image formed on the photosensitive drum 11 and transferring the transferred toner image to the sheet S. The intermediate transfer unit 20 is disposed substantially at the center in the image forming apparatus 2 in the present embodiment, and includes a driving roller 21, two tension rollers 22, 23, an intermediate transfer belt 24, a belt cleaning device 25, and the like. Yes.

  The driving roller 21 is disposed so as to be positioned below the image forming unit 10B, and is for rotating the intermediate transfer belt 24. A rotational driving force is transmitted from a motor (not shown). In FIG. 1, the tension rollers 22 and 23 are arranged so that the intermediate transfer belt 24 is in a straight line at the nip between the photosensitive drums 11 and the primary transfer rollers 15 in the image forming units 10B, 10Y, 10C, and 10M. One is provided on the left side of the photosensitive drum 11 of the image forming unit 10B and one is provided on the right side of the image forming unit 10M, and is rotatably supported.

  The intermediate transfer belt 24 is stretched around the drive roller 21, tension rollers 22 and 23, and the primary transfer rollers 15, and the drive roller 21 rotates to rotate counterclockwise as viewed from the front in FIG. Is driven to rotate. Further, as described above, the intermediate transfer belt 24 is stretched so as to pass through the nip formed by the photosensitive drum 11 and the primary transfer roller 15, and the toner image on the photosensitive drum 11 is transferred at a predetermined timing. By applying a transfer voltage to the primary transfer roller 15, primary transfer is performed on the intermediate transfer belt 24.

  The belt cleaning device 25 is for cleaning, removing, and collecting the secondary transfer residual toner T remaining on the surface of the intermediate transfer belt 24. A contact / separation mechanism (not shown) is connected to the intermediate transfer belt 24. 1 and is provided to the left of the drive roller 21 and the tension roller 22 in FIG.

  The secondary transfer unit 30 mainly includes a secondary transfer roller 31 and a drive roller 21. The secondary transfer roller 31 is for performing secondary transfer in which the toner image primarily transferred onto the intermediate transfer belt 24 is transferred to a sheet S such as paper. The secondary transfer roller 31 is pressed against the drive roller 21 via the intermediate transfer belt 24 by a contact / separation mechanism (not shown) at a predetermined timing. At this time, a transfer voltage is applied to the secondary transfer roller 31, and the toner image is transferred to the sheet S.

  The sheet supply unit 40 is for supplying a sheet S such as a copy sheet, an OHP sheet, or a label sheet to the secondary transfer unit 30. The sheet supply unit 40 includes a cassette 41, a pickup roller 42, a double feed prevention roller pair 43, and the like. The cassette 41 is for accommodating a plurality of sheets S, and has a box shape and an open upper surface. In addition, a placement plate 44 on which a plurality of sheets S are placed is provided in the cassette 41. A pickup roller 42 is provided at the upper right position of the cassette 41 in FIG. When a specific sheet supply operation is seen, a lift mechanism (not shown) provided on the placement plate 44 causes the uppermost sheet S placed on the pickup roller 42 to abut on the pickup roller 42. The sheets S are sent out one by one to the sheet conveyance path 50. A double feed prevention roller pair 43 is provided in the vicinity of the pickup roller 42 and on the downstream side in the sheet conveying direction. The double feed prevention roller pair 43 is configured such that each roller rotates in the same direction and prevents the sheet S from being conveyed while being overlapped.

  The sheet conveyance path 50 is for conveying the sheet S from the sheet supply unit 40 to the discharge unit 60 through the secondary transfer unit 30 and the fixing device 1, and includes a plurality of guides 51 and conveyance roller pairs 52. Has been. A registration roller pair 53 is provided on the upstream side of the secondary transfer unit 30 in the sheet conveyance direction. The registration roller pair 53 temporarily stops the conveyed sheet S, and the secondary transfer unit 30 forms a sheet. The sheet S is sent to the secondary transfer unit 30 at a predetermined timing and speed so that the toner image is transferred at an appropriate position of S. In FIG. 1, the sheet conveyance direction is indicated by a broken line.

  The fixing device 1 is for pressurizing and heating the toner image secondarily transferred to the sheet S to melt the toner T and fix it to the sheet S. Details will be described later.

  The discharge unit 60 is for discharging the sheet S on which an image is formed from the image forming apparatus 2, and a discharge roller pair 61 for discharging the sheet S is provided at the discharge port. Further, a discharge tray 61 for receiving the discharged sheet S is provided on the upper surface of the image forming apparatus 2, and a fixed number of image-formed sheets S can be placed thereon.

  Next, an image forming operation by the above-described image forming apparatus 2 will be described.

  When the image formation start signal is issued, the photosensitive drum 11 that is rotationally driven at a predetermined process speed is uniformly charged to the positive polarity by the charging roller 12. The exposure device 13 converts each input image signal into an optical signal, and performs scanning exposure on the photosensitive drum 11 charged with a laser. Thereby, an electrostatic latent image is formed.

  The electrostatic latent image formed on the photosensitive drum 11 is supplied with toner T by the developing device 14 to which a developing bias having the same polarity as the charging polarity (positive polarity) of the photosensitive drum 11 is applied, and the toner Visualized as an image. Thereafter, the toner image is rotated (moved) by a transfer roller to which a primary transfer bias (opposite polarity (negative polarity) with respect to toner T) is applied at a primary transfer portion between the photosensitive drum 11 and the transfer roller. Primary transfer is performed on the intermediate transfer belt 24.

  Here, when forming a color image, a black toner image is first temporarily transferred to the intermediate transfer belt 24 by the image forming unit 10B in the same process as described above. Next, the portion of the intermediate transfer belt 24 is rotationally moved to the image forming unit 10Y. Then, the yellow toner image is superimposed on the image forming unit 10Y. This process is repeated, and the cyan toner image is superimposed on the magenta toner image in the image forming unit 10M in the image forming unit 10C. In this manner, a primary transfer is performed on the intermediate transfer belt 24, and a full-color toner image is formed by only rotating the intermediate transfer belt 24 once.

  The toner images superimposed on the intermediate transfer belt 24 are secondarily transferred to the sheet S conveyed by the secondary transfer unit 50, and the sheet S is conveyed to the fixing device 1 so that the toner image is melted and fixed. And then discharged from the discharge unit 60.

  Next, the arrangement and structure of each member of the fixing device 1 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a perspective view of the fixing device 1 according to the first embodiment of the present invention.

  As shown in FIG. 2, the fixing device 1 according to the present embodiment includes a casing 71, a heating member 72, a pressure member 73, a pressure receiving member 74, a fixing member 75, a reinforcing member 76, and the like.

  The casing 71 is formed long in the left-right direction in FIG. That is, it is formed long in a direction parallel to the axial direction of the heating member 72 and the pressure member 73. And the housing | casing 71 is comprised from three members fundamentally. Specifically, the upper surface plate 71a having a rectangular shape and the cross section attached at the end in the longitudinal direction of the upper surface plate 71a are composed of two side plates 71b and 71c that are substantially L-shaped. The two side plates 71b and 71c are provided with an oval through hole 71d. The casing 71 configured as described above has a substantially U-shaped cross section when viewed from a direction perpendicular to the longitudinal direction of the upper surface plate 71a.

  As shown in FIG. 2, the heating member 72 is an endless belt. Specifically, the heating member 72 can have a cylindrical shape or a sleeve shape, and the heating member 72 in this embodiment has a cylindrical shape. A roller-shaped pressure member 73 is provided below the heating member 72 so as to be in contact with the heating member 72 and parallel to the axis of the heating member 72. A roller shaft 73a protrudes from both ends of the pressure member 73, and is separately supported by a case and other members of the image forming apparatus 1 so as to be rotatable. By connecting a motor (not shown), the pressure member 73 is driven to rotate at a predetermined speed. Accordingly, since the pressing member 73 is in pressure contact with the heating member 72, the heating member 72 is also rotated by the rotation of the pressing member 73. The pressurizing member 73 is formed longer in the axial direction than the heating member 72, and is arranged so that the midpoint of the heating member 72 and the midpoint of the pressurizing member 73 substantially coincide. Has been.

  In the longitudinal direction of the casing 71, a fixing member 75 is disposed below the through hole 71d so as to straddle the inside and outside of the side plates 71b and 71c. The fixing member 75 has a convex shape when viewed from the axial direction of the heating member 72. Further, the fixing member 75 is finally coupled to the casing 71 and fixed.

  As shown in FIG. 2, the pressure receiving member 74 and the reinforcing member 76 are fixed by the fixing member 75 inside the heating member 72 so as to be sandwiched between the fixing member 75 and the fixing member 75. As shown in FIGS. 2 and 3, a reinforcing member 76 is provided on the upper surface of the pressure receiving member 74 in contact with the pressure receiving member 74. The details of the positional relationship among the heating member 72, the pressure receiving member 74, and the reinforcing member 76 will be described later.

  Next, the detailed structure of the fixing device 1 according to the first embodiment will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view of the fixing device 1 according to the first embodiment of the present invention. In the following drawings, the casing 71 and the fixing member 75 are omitted for convenience of explanation.

  As shown in FIG. 3, the fixing device 1 according to the first embodiment includes at least a heating member 72, a radiation heat source 77, a pressure member 73, a pressure receiving member 74, and a reinforcing member 76. The sheet S on which the toner T is placed enters and passes through a nip formed between the heating member 72 and the pressure member 73, and fixing is performed.

  As shown in FIG. 3, the heating member 72 is formed of a thin film, for example, a metal film, and has an endless belt shape. Specifically, the heating member 72 in the present embodiment is formed in a sleeve shape or a cylindrical shape. Here, the heating member 72 in the present embodiment can have a thickness of about 30 μm, for example. Note that the thickness is not limited to 30 μm, and can be appropriately changed depending on the material of the heating member 72 and the thickness of the sheet S to be fixed. For example, the thickness may be 20 to 100 μm. Is possible.

  For the heating member 72, for example, SUS (stainless steel) can be used in view of heat capacity, strength, heat resistance, wear resistance, and the like. Here, in this embodiment, since the thickness is, for example, 30 μm, a stainless steel foil is used. For the heating member 72, not only a metal but also a resin such as polyimide can be used. Further, the surface (circumferential surface) of the heating member 72 may have a release layer whose release property is enhanced by a fluororesin or the like. Accordingly, the sheet S can be prevented from sticking to the heating member 72 due to the adhesiveness of the toner T melted and fixed by the sheet S that has passed through the nip, and the sheet S can be prevented from being clogged by the fixing device 1. be able to.

  Further, the heating member 72 in the present embodiment has a diameter of about 30 mm, but the diameter is not limited to this, and if the size is further reduced, for example, the diameter can be 20 mm, and the size is increased. In this case, for example, the diameter can be set to 40 mm, and can be appropriately set in consideration of the overall size of the fixing device 1. In the present embodiment, the heating member 72 has a width in the direction perpendicular to the sheet conveying direction (the direction perpendicular to the paper surface in FIG. 3), that is, a length in the longitudinal direction, of about 310 mm. Although it corresponds to the size in the vertical direction, this length can also be appropriately set according to the size of the sheet S used in the fixing device 1 and the image forming device 2.

  In the present embodiment, two radiant heat sources 77 are provided in the heating member 72 along the axial direction of the heating member 72 so as to sandwich the reinforcing member 76. The radiation heat source 77 is for heating the heating member 72. For the radiation heat source 77, for example, a halogen lamp can be used. The radiant heat source 77 is not limited to a halogen lamp, and a known one can be used as long as it can warm the heating member 72.

  Of the halogen lamps of the radiant heat source 77 in the present embodiment, one can be set to 500 W, for example, and the other can be set to 600 W, so that the output can be about 1100 W in total. Here, the outputs of the two radiant heat sources 77 may be the same, or may be different as in the present embodiment. Further, the output of the radiation heat source 77 is not limited to 500 W or 600 W, and can be appropriately changed by the fixing device 1. The two radiation heat sources 77 (halogen lamps) do not always have to be operated at the same time. Both the heating members 72 are used when the heating members 72 are rapidly warmed, such as when the image forming apparatus 2 is activated. When fixing is performed continuously in a sufficiently warmed state, it is possible to perform control such that only one of them is used as an auxiliary to maintain the temperature of the heating member 72. That is, the temperature control of the heating member 72 can be accurately performed, and power saving can be achieved. With such a configuration, the thin heating member 72 is rapidly heated to about 200 ° C. necessary for melting the toner T.

  The pressure member 73 is provided so as to be in pressure contact with the heating member 72. For example, the pressing member 73 is cylindrical, that is, a roller, and is formed of rubber such as silicon rubber. Then, when the pressing member 73 is pressed against the heating member 72, a nip portion N is formed between the pressing member 73 and the heating member 72. By passing the sheet S on which the toner image is transferred to the nip portion N, the sheet S is heated by the heating member 72 and pressurized by the pressure member 73. As a result, the toner T on the sheet S is melted and fixed on the sheet S.

  The pressure member 73 in the present embodiment has a diameter of 25 mm, of which the roller shaft 73a has a diameter of 12 mm. Further, the width of the pressure member 73 in the direction perpendicular to the sheet conveying direction (the direction perpendicular to the paper surface in FIG. 3), that is, the length in the longitudinal direction is about 316 mm, and corresponds to the longitudinal size of A4 paper. However, it is slightly longer than the heating member 72. Thereby, the pressure can be reliably applied over the entire range of the nip portion N with the heating member 72, and the fixing pressure is stabilized. The length of each part in the pressure member 73 can be appropriately set according to the size of the sheet used in the fixing device 1 and the image forming apparatus 2.

  As shown in FIG. 3, the pressure receiving member 74 is formed inside the heating member 72 and extends in the axial direction of the heating member 72, and the pressure member 73 is formed at the nip between the heating member 72 and the pressure member 73. It is for receiving pressure and is provided in contact with the heating member 72. That is, it can be said that the pressure receiving member 74 forms the nip portion N with the pressure member 73 through the heating member 72.

  The pressure receiving member 74 needs to have a certain strength in order to receive the pressure. For example, SUS (stainless steel) can be used, and in this embodiment, a member having a thickness of about 0.1 mm can be used. The thickness is not limited to 0.1 mm, and can be changed as appropriate in accordance with the strength of the pressure at the nip portion N. Further, since the pressure receiving member 74 is in contact with the sliding heating member 72, it is necessary to have not only heat capacity, strength and heat resistance but also excellent wear resistance. In addition, if it has the said conditions, it is also possible to use resin. In addition, since the pressure receiving member 74 uses SUS of about 0.1 mm, for example, the heat capacity can be reduced, and the temperature rise of the heating member 72 is not hindered.

  Here, looking at the specific shape of the pressure receiving member 74, the pressure receiving member 74 has a substantially C-shaped cross section in FIG. 3 and is substantially perpendicular to the contact surface portion 74 a that contacts the heating member 72. There are two side walls 74b. And the connection surface 74c which connects the contact surface part 74a and the side wall part 74b is formed, and the C surface is formed. By having this C surface, sliding of the heating member 72 becomes smooth.

  The reinforcing member 76 has a substantially T-shaped cross section in FIG. 3 and is provided to receive the pressure received by the pressure receiving member 74 from the pressing member 73, that is, to assist and reinforce the pressure receiving member 74. . Therefore, the reinforcing member 76 is configured to extend in the axial direction of the heating member 72 and is abutted against the pressure receiving member 74 and is sandwiched between the groove portions 75a of the fixing member 75 to be supported and fixed (see FIG. 2). . Due to the presence of the reinforcing member 76, the pressure (fixing pressure) at the nip portion N is stabilized and the pressure can be increased more than before, and the pressure can be reliably applied to the sheet S passing through the nip portion N. And fixing failure can be eliminated.

  By providing the reinforcing member 76, the pressure receiving member 74 can be made thinner compared to the case where the pressure receiving member 74 alone receives pressure from the pressure member 73, and the heat capacity of the pressure receiving member 74 can be reduced compared to the conventional case. Can do. Therefore, the temperature rise of the heating member 72 during the warm-up of the image forming apparatus 2 and the maintenance of the temperature of the heating member 72 when performing continuous fixing are prevented. That is, the pressure receiving member 74 does not remove heat from the heating member 72. In addition, since the reinforcing member 76 is abutted against the pressure receiving member 74, the pressure from the pressure member 73 can be sufficiently received even if the reinforcing member 76 itself is thinned, compared to the case where only the pressure receiving member 74 is provided and formed thick. However, the heat capacity can be lowered while having the same strength.

  Here, reflection of radiation light of the fixing device 1 in the present embodiment will be described. As shown in FIG. 3, in the fixing device 1, reflection films 80 and 81 are provided for the reinforcing member 76 and the radiation heat source 77, respectively.

  First, the reflective film 80 in the reinforcing member 76 will be described. The reinforcing member 76 of the fixing device 1 according to the present exemplary embodiment is provided with a reflective film 80 on the surface thereof so that the radiant light can be efficiently reflected. As the reflective film 80, for example, the reinforcing member 76 can be plated with aluminum. The metal to be plated is not limited to aluminum, but other metals having high reflectivity such as gold and silver can be used, but aluminum is advantageous in terms of cost. Further, since the reflection film 80 is provided to reflect the radiation light, the reflection film 80 in the reinforcing member 76 may be provided in a portion where the radiation light from the radiation heat source 77 is applied.

  On the other hand, the reflective film 81 provided on the radiation heat source 77 can be a coating layer made of ceramic or the like in consideration of heat resistance. The reflective film 81 in the radiant heat generation source 77 is for preventing the radiant light from being directly applied to the heating member 72 from the radiant heat generation source 77. Therefore, the reflection film 81 of the radiation heat source 77 in FIG. 3 is semicircular, and the peripheral surface portion of the peripheral surface of the radiation heat source 77 that is close to the radiation heat source 77 and the heating member 72 is covered. In addition, a reflective film 81 is provided. In other words, the reflective film 81 is not provided on the peripheral surface portion of the peripheral surface of the radiation heat source 77 that faces the reinforcing member 76.

  Further, by providing such a reflection film 80, 81 on the reinforcing member 76 and the radiation heat source 77, it is possible to prevent direct irradiation of the heating member 72, and the heating member 72 is reflected at least once. The emitted radiation light finally strikes the heating member 72. In the process of being reflected, the radiant light diffuses moderately, so even if there is a variation in the intensity of the radiant light emitted from the peripheral surface of the radiant heat source 77, temperature unevenness is present on the outer surface of the heating member 72. It can be prevented from occurring.

  Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different in that the reflective films 80 and 81 in the first embodiment are replaced with reflective members 82 and 83. FIG. 4 is a schematic cross-sectional view of the fixing device 1 according to the second embodiment of the present invention.

  Since the basic configuration of the second embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 3, the configuration common to the above embodiment is described in the drawings. And explanation about explanation and operation effects is omitted. That is, except for the difference in which the reflecting films 80 and 81 are replaced with the reflecting members 82 and 83, the same effects as those in the first embodiment described with reference to FIGS. Have.

  In this embodiment, instead of the reflecting films 80 and 81 provided on the reinforcing member 76 and the radiation heat source 77, for example, reflecting members 82 and 83 obtained by applying aluminum plating or ceramic coating to a plate-like aluminum metal plate are provided. Provide.

  The reflecting member 82 provided on the reinforcing member 76 is bent in accordance with the surface shape of the reinforcing member 76 and has a substantially L-shaped cross section as shown in FIG. The reflecting member 82 is attached to a surface where the reinforcing member 76 faces the radiation heat source 77. On the other hand, the reflection member 83 provided in the radiant heat source 77 is a peripheral surface portion that is close to the radiant heat source 77 and the heating member 72 so that the direct radiant light does not hit the heating member 72 as in the first embodiment. It is attached to the radiation heat source 77 so as to cover. Therefore, the reflecting member 83 has a semicircular cross section.

  Thus, by providing the reflecting members 82 and 83, it is not necessary to perform plating or coating on the reinforcing member 76 or the radiation heat source 77. That is, in the manufacture of the fixing device 1, it is only necessary to provide the reflection member on the reinforcing member 76 and the radiation heat source 77, and the manufacturing process may be simplified.

  In this way, an endless belt-like thin heating member 72, a radiant heat source 77 disposed in the heating member 72, and a heating member so as to form a nip portion N for passing and heating and pressurizing the sheet are formed. A pressure member 73 that is in pressure contact with the pressure member 72 and rotationally driven; a pressure receiving member 74 provided in contact with the heating member 72 inside the heating member 72 to receive pressure from the pressure member 73 in the nip portion N; In the fixing device 1 including the reinforcing member 76 protruding from 74, a reflective film 81 or a reflective member 83 is provided on a part of the radiant heat source 77 so that the radiant light does not directly strike the heating member 72 from the radiant heat source 77. If the reinforcing member 76 is provided with the reflective film 80 or the reflective member 82 for reflecting the radiation light from the radiation heat source 77, the radiation from the radiation heat source 77 is provided. By providing the reflection films 80 and 81 or the reflection members 82 and 83 on the radiation heat source 77 and the reinforcing member 76 without directly applying the light to the heating member 72, the radiation light is reflected and diffused to some extent. Thus, radiation light is applied to the inner surface of the heating member 72. Therefore, even when an endless belt-like thin heating member 72 is used, temperature unevenness on the outer surface of the heating member 72 can be prevented. Accordingly, since the heating member 72 can be uniformly and rapidly heated, it is easily achieved that the heating member 72 is maintained at a temperature required for fixing even if continuous fixing is performed, and on the outer surface of the heating member 72. In addition, it is possible to prevent a low temperature portion and a high temperature portion from being formed, and a stable fixing property can be ensured. In addition, it is not necessary to wait for the temperature of the low temperature part to rise in order to avoid fixing failure, and the warm-up time for warming the heating member 72 can be shortened.

  Furthermore, the heating member 72 has an endless belt shape, is formed thinner than a conventional heating roller, and can quickly warm the heating member. Therefore, in this respect as well, the warm-up time can be extremely shortened, User convenience is enhanced. Further, since it is not necessary to preheat the heating member 72, power saving can be achieved.

  If aluminum is used for the reflective film 80 and the reflective member 82, the fixing device 1 that is advantageous in terms of cost can be provided.

  If the image forming apparatus 2 is provided with these fixing devices 1, the high-quality image forming device 2 that has a short warm-up, a stable fixing property, high user convenience, and low power consumption can be obtained. Can be provided.

  Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different in that a difference is provided in the shape of the reinforcing member 76 in the first and second embodiments. FIG. 5 is a schematic cross-sectional view of the fixing device 1 according to the third embodiment of the present invention.

  The basic configuration of the third embodiment is the same as that of the first and second embodiments described with reference to FIGS. The description of the drawings, the description, and the effects are omitted. That is, the points other than the shape of the reinforcing member 76 may be the same as those in the first and second embodiments described with reference to FIGS. Have.

  In the present embodiment, the reinforcing member 760 is formed so as to have an inclined surface 760a for diffusing the radiated light with respect to the direction thrusting the pressure receiving member 74. By having this inclined surface 760a, it is possible to prevent radiation light from the radiation heat source 77 from returning to the radiation heat source 77 as much as possible.

  Furthermore, the reinforcing member 760 in the present embodiment has a substantially rhombus shape in a cross section viewed from the circumferential direction. In the present embodiment, the two opposing vertices 760b of the rhombus are positioned approximately on a straight line connecting the centers of the two radiation heat sources 77, and the radiation from the radiation heat source 77 is obtained. Divide the light into two. By configuring the reinforcing member 760 in this way, it is possible to prevent the radiant light from the radiant heat source 77 from returning to the radiant heat source 77 and to go to the heating member 72.

  In this way, if the reinforcing member 760 is formed to have the inclined surface 760a for diffusing the radiated light with respect to the direction thrust against the pressure receiving member 74, the radiant heat source 77 is formed by the reflection surface having an angle. Therefore, the heating member 72 can be efficiently warmed. That is, the warm-up time can be further shortened and stable fixing properties can be secured.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a fixing device in an image forming apparatus and an image forming apparatus using the same.

1 is a schematic cross-sectional view seen from the front showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention. 1 is a perspective view of a fixing device according to a first embodiment of the present invention. 1 is a schematic cross-sectional view of a fixing device according to a first embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a fixing device according to a second embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a fixing device according to a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing apparatus 2 Image forming apparatus 72 Heating member 73 Pressure member 74 Pressure receiving member 76, 760 Reinforcement member 77 Radiation heat source 80, 81 Reflective film 82, 83 Reflective member N Nip part

Claims (4)

An endless belt-shaped heating member, a radiant heat source disposed in the heating member, and a pressurizing member that is in pressure contact with the heating member so as to form a nip through which a sheet is passed and heated and pressed. A fixing device comprising: a member; a pressure receiving member provided in contact with the heating member inside the heating member so as to receive pressure from the pressure member at the nip; and a reinforcing member thrust against the pressure receiving member. ,
A reflective film or a reflective member is provided on a part of the radiation heat source so that radiation light does not directly hit the heating member from the radiation heat source,
The fixing device, wherein the reinforcing member is provided with a reflection film or a reflection member for reflecting radiation light from the radiation heat source.   The fixing device according to claim 1, wherein the reinforcing member is formed to have an inclined surface for diffusing radiant light with respect to a direction in which the reinforcing member is thrust.   The fixing device according to claim 1, wherein aluminum is used for the reflection film and the reflection member.   An image forming apparatus comprising the fixing device according to claim 1.

Images