JP2010217492A - Fixing device and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device for preventing thermal deformation of a device casing with a simple configuration, and an image forming apparatus equipped with the same. <P>SOLUTION: The fixing device 5 includes a heat roller 18 incorporating first to third heaters 43-45 for heating a toner image on a sheet 9, the device casing 50 for holding the heat roller 18 at both ends in the axial direction of the heat roller 18, and a heat reflection face 55a disposed on the end part side in the axial direction inside the heat roller 18. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine using the electrophotographic method, and an image forming apparatus provided with the fixing device. And an image forming apparatus including the same.

  2. Description of the Related Art Conventionally, a fixing device has a heating member and a pressure member that presses the heating member, and a toner image on a sheet is heated and fixed at a pressure contact portion between the heating member and the pressure member. Normally, in this fixing device, the paper conveyed in a substantially vertical direction from the lower side to the upper side of the device case is fixed by passing through the press contact portion, and then discharged through an upper opening formed in the device case. It has become so.

  The heat generated in the fixing device is released upward from the upper opening of the device casing. A paper detection sensor, a reading optical system, and the like are arranged immediately above the fixing device. However, since these members and units may deteriorate in performance due to heat, it is necessary to minimize heat as much as possible. is there. Further, in order to heat and fix the toner image on the paper, it is necessary to keep the temperature of the heating member constant.

  Therefore, in Patent Document 1, an upper opening is formed in a resin casing of the fixing device, and an opening / closing plate for opening and closing the upper opening is disposed on the upper portion of the casing forming the opening. One end of the opening / closing plate is pivotally supported on the upper portion of the housing, and is arranged to be swingable within a range of 60 degrees or less by the stiffness and conveying force of the sheet in the sheet conveying direction. When the fixed paper passes through the upper opening, the open / close plate is pushed up by the stiffness and conveying force of the paper to change from the closed state to the open state. Return to the closed state. This suppresses the release of heat to the outside of the casing as much as possible, suppresses the temperature rise of members and units located above the casing, and suppresses the temperature drop inside the casing.

  However, in the above-described prior art, the heat in the heating member is not sufficiently utilized for the heat fixing action on the paper, there is still wasteful heat dissipation, and the heating member is in the closed state. In contrast to the heat radiated from the heater for heating the housing, the casing in the vicinity of the heater cannot withstand the heat and may be thermally deformed.

  Therefore, in Patent Document 2, a heating member having a built-in heater, a pressure member in pressure contact with the heating member, a reflecting plate that covers the periphery of the heating member with a slight space therebetween, and the reflecting plate And an apparatus housing disposed with a space therebetween. As a result, the radiant heat of the heating member is reflected by the reflecting plate and returned to the heating member, and the device housing is attached to the outside of the reflecting plate with a space so that an air layer is provided between the reflecting plate and the heating plate. It has been.

  In the prior art described above, the air layer provided between the reflection plate and the apparatus housing suppresses the reflection plate from being cooled by the flow of the airflow, thereby preventing heat loss of the heating member. Further, by covering the periphery of the heating member with the reflecting plate, there is no possibility that the apparatus housing disposed around the heating member is thermally deformed. However, the side surface portion of the apparatus housing that holds the end portion of the heater in the heating member is heated to a high temperature by the heater.

Japanese Patent Laying-Open No. 2003-241551 (paragraphs [0008] to [0011], FIG. 2) Japanese Patent Laid-Open No. 5-188805 (paragraphs [0019] to [0023], FIG. 1)

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device that prevents thermal deformation of an apparatus housing with a simple configuration and an image forming apparatus including the fixing device. .

  In order to achieve the above object, the present invention includes a heat roller that incorporates a heater for heating a toner image on a sheet, and an apparatus housing that holds the heat roller at both axial ends of the heat roller. And a heat reflecting surface disposed on the end side in the axial direction inside the heat roller.

  According to this configuration, the heater dissipates heat in the circumferential direction in the heat roller, whereby the heat roller is heated, and the toner image is heat-fixed on the paper by the heat of the heat roller. The heater also radiates heat in the axial direction inside the heat roller, but this heat is reflected by the heat reflecting surface, preventing heat from being transferred to the corresponding device case inside the heat roller. Is suppressed.

  The invention according to claim 2 is characterized in that a plurality of the heaters are arranged side by side in the axial direction, and the heat reflecting surface is disposed at a position corresponding to the space between the plurality of heaters. According to this configuration, the heat distribution is such that the temperature between the plurality of heaters is higher than the peripheral surface of the heat roller. However, by disposing the heat reflecting surface at a position corresponding to the plurality of heaters, Overheating to the body is effectively suppressed.

  According to a third aspect of the present invention, the apparatus housing includes a housing and a holding member attached to the housing, and the heat reflecting surface and the heater are provided on the holding member. Yes. According to this configuration, the heat reflecting surface and the heater are attached to the holding member, and then the holding member is attached to the housing.

  According to a fourth aspect of the present invention, the heat reflecting surface is formed on a metal plate.

  According to a fifth aspect of the present invention, the metal plate has a connection terminal portion connected to a terminal portion provided in the heater.

  According to a sixth aspect of the present invention, a pressure roller is provided in pressure contact with the heat roller, and a toner image on the paper is heat-fixed at a nip portion between the heat roller and the pressure roller. It is said.

  According to a seventh aspect of the present invention, an endless fixing belt is stretched between the heat roller and the fixing roller, and a pressure roller is provided in pressure contact with the fixing roller via the fixing belt. A toner image on a sheet is heat-fixed at a nip portion where the pressure roller is in pressure contact.

  According to an eighth aspect of the present invention, there is provided an image forming apparatus equipped with the fixing device having the above configuration.

  According to the first aspect of the present invention, the heater dissipates heat in the circumferential direction within the heat roller, whereby the heat roller is heated, and the toner image is heat-fixed on the paper by the heat of the heat roller. In addition, the heater radiates heat in the axial direction inside the heat roller, but this heat is reflected by the heat reflecting surface, preventing the heat from being transferred to the device housing corresponding to the inside of the heat roller. An increase in temperature of the housing can be suppressed, and thermal deformation of the device housing can be prevented.

  According to the second aspect of the present invention, when a plurality of heaters are arranged side by side in the axial direction, the heat distribution is such that the temperature between the plurality of heaters is higher than the peripheral surface of the heat roller. By disposing the heat reflecting surface at a position corresponding to the above, overheating to the apparatus casing can be efficiently suppressed, and thermal deformation of the apparatus casing can be prevented.

  According to the invention described in claim 3, since the heat reflecting surface and the heater are attached to the holding member, and then the holding member is attached to the housing, the heat reflecting surface and the heater can be easily assembled. . Moreover, since the housing and the holding member are provided separately, materials can be selected as appropriate according to the heat resistance and strength characteristics required for each member.

  In addition, according to the invention of claim 4, since the heat reflecting surface is formed on the metal plate, the heat reflecting surface can use the gloss of the metal plate, without performing special treatment, The heat reflecting surface can be formed with a simple member.

  According to the invention described in claim 5, since the metal plate has both the connection terminal electrically connected to the heater and the heat reflecting surface, the assembling is simplified and the apparatus is downsized. Can do.

  According to the invention described in claim 6, the pressure roller that presses against the heat roller is provided, and the toner image on the paper can be heat-fixed at the nip portion between the heat roller and the pressure roller, Further, the heat reflection surface disposed on the end side in the axial direction on the inner side of the heat roller can suppress the temperature rise of the device case corresponding to the inner side of the heat roller, and can prevent the heat deformation of the device case. .

  According to the seventh aspect of the present invention, the pressure belt includes a pressure roller that stretches an endless fixing belt between the heat roller and the fixing roller and presses the fixing roller via the fixing belt. The toner image on the paper can be heated and fixed at the nip portion where the roller is pressed. Further, the heat reflection surface disposed on the end side in the axial direction on the inner side of the heat roller can suppress the temperature rise of the device case corresponding to the inner side of the heat roller, and can prevent the heat deformation of the device case. .

  According to the eighth aspect of the present invention, an image forming apparatus including a fixing device that prevents thermal deformation of the apparatus housing can be provided with a simple configuration.

FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 1 is a diagram illustrating a schematic configuration of a fixing device used in an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view partially showing a heat roller of the fixing device according to the first embodiment of the present invention. FIG. 3 is a perspective view of the main part of the fixing device showing a state before the heater according to the first embodiment of the present invention is attached. FIG. 3 is an exploded perspective view of an attachment portion for a heater and a heat reflecting member in the fixing device according to the first embodiment of the present invention. These are perspective views which show the heat | fever reflecting member used for the fixing device which concerns on 1st Embodiment of this invention. FIG. 3 is a perspective view showing a holding member used in the fixing device according to the first embodiment of the present invention. FIG. 3 is a partially sectional side view showing a holding member to which a heater and a heat reflecting member of the fixing device according to the first embodiment of the present invention are attached. These are the figures which show schematic structure of the holding member which attached the heat | fever reflection member of the fixing device which concerns on 1st Embodiment of this invention. FIG. 3 is a diagram showing a schematic configuration of a fixing device used in an image forming apparatus according to a second embodiment of the present invention. These are the partial sectional side views which show the holding member which attached the heater and heat reflection member of the fixing device which concerns on 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Further, the use of the invention and the terms shown here are not limited thereto.

(First embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is provided with a sheet feeding unit 2 disposed in a lower portion thereof, a sheet conveying unit 3 disposed on a side of the sheet feeding unit 2, and an upper side of the sheet conveying unit 3. The image forming unit 4, the manual feed tray 25 disposed outside the apparatus on the right side of the image forming unit 4, the fixing device 5 disposed on the discharge side of the image forming unit 4, the image forming unit 4 and the fixing unit An image reading unit 6 disposed above the apparatus 5 is provided.

  The paper feed unit 2 includes a plurality of paper feed cassettes 7 for containing paper 9, and the paper 9 is fed from the selected paper feed cassette 7 among the plurality of paper feed cassettes 7 by the rotation of the paper feed roller 8. Each sheet is surely sent out to the sheet transport unit 3.

  The manual feed tray 25 is loaded with paper having a size different from that of the paper 9 stored in the paper feed cassette 7 or a recording material such as an OHP sheet or envelope, and sends the paper, OHP sheet, envelope, or the like to the paper transport unit 3. .

  The paper 9 sent to the paper transport unit 3 is transported toward the image forming unit 4 via the paper supply path 10. The image forming unit 4 forms a toner image on a sheet 9 by an electrophotographic method. The photosensitive member 11 is rotatably supported in a predetermined direction (the arrow direction in FIG. 1), and the photosensitive member 11. A charging device 12, an exposure device 13, a developing device 14, a transfer device 15, a cleaning device 16, and a charge removal device 17 are provided around the rotation direction of the device.

  The charging device 12 includes a charging wire to which a high voltage is applied. When a predetermined potential is applied to the surface of the photoconductor 11 by corona discharge from the charging wire, the surface of the photoconductor 11 is uniformly charged. Then, laser light based on the image data of the original read by the image reading unit 6 is irradiated to the photoconductor 11 by the exposure device 13. The surface potential of the photoconductor 11 is selectively attenuated by the irradiated laser light, and an electrostatic latent image is formed on the surface of the photoconductor 11. Next, the developing device 14 develops the electrostatic latent image on the surface of the photoconductor 11, and a toner image is formed on the surface of the photoconductor 11. This toner image is transferred by the transfer device 15 onto the paper 9 supplied between the photoreceptor 11 and the transfer device 15.

  The sheet 9 on which the toner image has been transferred is conveyed toward the fixing device 5 disposed downstream of the image forming unit 4 in the sheet conveying direction. In the fixing device 5, the paper 9 is heated and pressed by the heat roller 18 and the pressure roller 19, and the toner image is fixed on the paper 9. Next, the sheet 9 on which the toner image is fixed is discharged onto the discharge tray 21 by the discharge roller pair 20.

  After the transfer by the transfer device 15, the toner remaining on the surface of the photoconductor 11 is removed by the cleaning device 16, and the residual charge on the surface of the photoconductor 11 is removed by the charge eliminating device 17. Then, the photoreceptor 11 is charged again by the charging device 12, and image formation is performed in the same manner.

  The fixing device 5 will be described in detail with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of the fixing device 5 used in the image forming apparatus 1 described above.

  The fixing device 5 is a roller fixing method, and includes a heat roller 18 as a heating member, a pressure roller 19, a plurality of heaters 43 to 45 as a heat source, and a drive source 49 having a motor, a reduction gear, and the like. .

  The heat roller 18 has a cylindrical cored bar made of a metal such as aluminum or iron having excellent thermal conductivity, and the cored bar is coated with a fluororesin coating or a tube. Three heaters 43 to 45 such as halogen lamps are provided inside the core of the heat roller 18.

  The plurality of heaters 43 to 45 are arranged at a position equal to the circumference of the heat roller 18 and equally spaced from the circumferential surface of the heat roller 18. The plurality of heaters 43 to 45 have different heat distributions in the axial direction of the heat roller 18. For example, the first heater 43 has a small amount of heat distribution at one end in the axial direction compared to other parts, the second heater 44 has a large amount of heat distribution at one end compared to other parts, and the third heater 45 The central portion has a heat distribution that has a larger heat distribution amount than other portions.

  The pressure roller 19 is a resin in which an elastic layer such as silicon rubber is formed on a cylindrical base material made of synthetic resin, metal or other material, and the surface of the elastic layer is excellent in releasability such as fluororesin. The one covered with is used. A nip portion N is formed at a portion where the pressure roller 19 contacts the heat roller 18. When the pressure roller 19 comes into contact with the heat roller 18, the elastic layer is elastically deformed, and the nip pressure due to the elastic deformation pressure acts on the nip portion N.

  The driving source 49 is gear-connected to the heat roller 18 and transmits the driving force from the motor to the heat roller 18 through the gear. When the motor is driven to rotate, the heat roller 18 rotates in the direction of the arrow in FIG. The rotation of the heat roller 18 causes the pressure roller 19 in pressure contact with the heat roller 18 to follow and rotate in the direction of the arrow in FIG. 2, and the heat roller 18 and the pressure roller 19 rotate in the opposite directions.

  The sheet 9 is guided by the conveyance guide 40 and is nipped and conveyed by the nip portion N. The nip portion N is heated and pressed by the heat roller 18 and the pressure roller 19, so that the powder state on the sheet 9 is changed. The toner is fixed by heating. Further, due to the rotation of the heat roller 18 and the pressure roller 19, the fixed sheet 9 is separated from the heat roller 18 and conveyed to the left in FIG.

  Next, attachment of the heat roller and the heater to the apparatus housing will be described with reference to FIGS. FIG. 3 is a perspective view partially showing a mounting portion of the heat roller, and FIG. 4 is a perspective view of a main portion showing a state before the heater is attached to the apparatus housing.

  As shown in FIG. 3, the heat roller 18 has a mounting shaft 18a on one end side in the axial direction. The mounting shaft 18 a is rotatably held by a bearing provided in the upper housing 51. Further, the other end side of the heat roller 18 is also rotatably held by the upper casing 51 in the same manner as the one end side.

  As shown in FIG. 4, the upper housing 51, the holding member 52 attached to the upper housing 51, and the lower housing 53 constitute an apparatus housing 50. The upper housing 51 is made of resin and rotatably supports a gear of a drive source 49 that rotates the heat roller 18 together with the heat roller 18 (see FIG. 3). The lower casing 53 is provided below the upper casing 51 and holds the pressure roller 19 (not shown) in a freely rotatable manner.

  The holding member 52 is formed of a resin having heat resistance such as a liquid crystal polymer. One end side of the first to third heaters 43 to 45 in the axial direction is attached to the holding member 52. On the other end side of the first to third heaters 43 to 45, although not shown, lead wires for electrical connection to a power source or the like are provided.

  In order to attach the first to third heaters 43 to 45 to the upper housing 51, the first to third heaters 43 to 45 are attached to the holding member 52, and the first to third heaters 43 to 45 attached to the holding member 52 are attached. Is inserted into the heat roller 18 (see FIG. 3) from the opening 51a formed in the upper casing 51. After the first to third heaters 43 to 45 are inserted in the direction of the arrow in FIG. 4, the holding member 52 is attached to the upper housing 51 with a screw (not shown). Next, the other end sides of the first to third heaters 43 to 45 are attached to a sheet metal (not shown), and the lead wires are connected to a power source or the like.

  Next, the detailed attachment structure of the 1st-3rd heaters 43-45 to the holding member 52 and the structure of a heat | fever reflection member are demonstrated using FIGS. FIG. 5 is an exploded perspective view illustrating a configuration in which the first to third heaters 43 to 45 and the heat reflecting member are attached to the holding member 52. FIG. 6 is a perspective view showing the heat reflecting member, and FIG. 7 is a perspective view showing the holding member 52. In FIG. 5, nuts for attaching the second and third heaters 44 and 45 are omitted.

  As shown in FIG. 5, in order to attach the first to third heaters 43 to 45 to the holding member 52, a nut 58 and a screw 59 are provided in addition to the first to third heaters 43 to 45 and the heat reflecting member 55. It is done.

  The first to third heaters 43 to 45 include a glass tube containing a tungsten filament and enclosing a halogen gas, and lead wires 43a to 45a protruding from the end of the glass tube. The lead wires 43a to 45a are soldered to the first to third terminal portions 46 to 48 having conductivity. Holes 46 a to 48 a are formed in the first to third terminal parts 46 to 48. The first terminal portion 46 is disposed to extend to the upper side of the holding member 52, and the second and third terminals 47 and 48 are disposed to extend into the opening 52 g formed on the lower side of the holding member 52.

  The first terminal portion 46 is attached to the holding member 52 by bringing the first terminal portion 46 crimped and soldered to the first heater 43 onto the heat reflecting member 55 already placed on the holding member 52. The configuration and attachment of the heat reflecting member 55 will be described in detail later. In this state, the screw 59 is inserted through the hole 46 a of the first terminal portion 46 and the mounting hole 55 c of the heat reflecting member 55. The first terminal portion 46 is attached to the holding member 52 by screwing the inserted screw 59 into the screw hole 58 a of the nut 58 inserted below the holding member 52.

  The attachment of the second and third heaters 44 and 45 to the holding member 52 of the second and third terminal portions 47 and 48 is the same as the attachment of the first terminal portion 46 to the holding member 52, and the nut 58 and the screw 59. It is done using. The second and third terminal portions 47 and 48 are attached to the holding member 52 without the heat reflecting member 55 interposed.

  Next, attachment of the heat reflecting member 55 to the holding member 52 will be described.

  As shown in FIG. 6, the heat reflecting member 55 reflects the heat radiated from the heater, is glossy, reflects radiant heat, and is formed of a material having a relatively high thermal conductivity. For example, a thin stainless steel plate or aluminum plate is used for the heat reflecting member 55. The heat reflecting member 55 is formed by bending and has an attachment portion 55b, a heat reflection surface 55a, and an attachment portion 55e.

  The attachment portion 55 b is a portion attached to the holding member 52, and has an attachment hole 55 c through which the screw 59 (see FIG. 5) is inserted and a notch portion 55 d that is positioned with respect to the holding member 52. A pair of notches 55d are formed on both side end surfaces.

  The heat reflection surface 55a is continuously provided by being bent in a substantially L shape below the attachment portion 55b via an inclined surface, and spreads in the left-right direction in FIG. When the heat reflecting member 55 is attached to the holding member 52, the heat reflecting surface 55a reflects the heat radiated in the axial direction of the first to third heaters 43 to 45, and from the first to third heaters 43 to 45. Is prevented from being transferred to the holding member 52.

  The attachment part 55e is bent and connected in a substantially L shape below the heat reflection surface 55a, and protrudes from the heat reflection surface 55a in a direction facing the attachment part 55b. The heat reflecting member 55 has elasticity in the bent direction (the axial direction of the heat roller 18 when the heat reflecting member 55 is attached to the holding member 52), and this attachment is performed when the heat reflecting member 55 is attached to the holding member 52. The portion 55e holds the holding member 52 together with the attachment portion 55b.

  As shown in FIG. 7, the holding member 52 has a flat portion 52b, a facing portion 52a, a locking portion 52e, and a screw mounting hole 55g for screwing the holding member 52 to the upper housing 51 (see FIG. 4). And have.

  The flat surface portion 52b faces the attachment portion 55b (see FIG. 6) of the heat reflecting member 55 so that the heat reflecting member 55 can be attached thereto. A pair of protrusions 52d into which the cutout portions 55d (see FIG. 6) of the heat reflecting member 55 are fitted and a long hole portion 52c through which the screws 59 (see FIG. 5) are inserted are formed in the flat surface portion 52b.

  The facing portion 52a has a surface extending in a direction orthogonal to the axial direction of the first to third heaters 43 to 45 (see FIG. 5) between the flat surface portion 52b and the opening portion 52g. A portion having the heat reflecting surface 55a (see FIG. 6) can be contacted.

  The locking portion 52e is formed on the upper surface in the opening 52g below the flat portion 52b, and can be engaged with the mounting portion 55e (see FIG. 6) of the heat reflecting member 55.

  The attachment of the heat reflecting member 55 to the holding member 52 will be described with reference to FIGS. 6 and 7. The cutout portion 55 d of the heat reflecting member 55 is fitted into the protrusion 52 d of the holding member 52, and the mounting portion 55 b of the heat reflecting member 55 is brought into contact with the flat portion 52 b of the holding member 52. When all of the attachment portions 55b come into contact with the flat surface portion 52b, the attachment portion 55e of the heat reflection member 55 engages with the engaging portion 52e of the holding member 52 by the elasticity of the heat reflection member 55, and has the heat reflection surface 55e. The part comes into contact with the facing part 52a. Thus, the heat reflecting member 55 is held by the holding member 52.

  Next, to attach the first heater 43 to the holding member 52, the first terminal portion 46 is brought into contact with the heat reflecting member 55 as described above with reference to FIG. 5. Next, the screw 59 is inserted through the hole 46 a of the first terminal portion 46, the attachment hole 55 c of the heat reflecting member 55, and the long hole portion 52 c of the holding member 52. The first heater 43 is attached to the holding member 52 by screwing the inserted screw 59 into the screw hole 58 a of the nut 58.

  The state in which the heat reflecting member 55 and the first heater 43 are attached is shown in FIGS. FIG. 8 is a partially sectional side view showing the holding member to which the heater and the heat reflecting member are attached. FIG. 9 is a schematic configuration diagram showing the arrangement of the heat reflecting surface with respect to the heater. FIG. 9 shows a state in which the terminal portions 46 to 48 are omitted and the screw 59 and the nut 58 are removed from the holding member 52.

  As shown in FIG. 8, the holding member 52 has a flat surface portion 52b, a facing portion 52a, and a locking portion 52e, and the flat surface portion 52b, the facing portion 52a, and the locking portion 52e are formed in a U-shaped cross section. . The heat reflecting member 55 and the first terminal portion 46 are disposed on the flat portion 52b. In this state, a screw 59 is screwed into a nut 58 disposed in a gap 52f formed by the flat portion 52b, the facing portion 52a, and the locking portion 52e. The second heater 44 and the third heater 45 are attached to the holding member 52 in the same manner as the first heater 43 without the heat reflecting member 55 interposed.

  The first to third heaters 43 to 45 attached to the holding member 52 are inserted into the heat roller 18, and the holding member 52 is attached to the upper housing 51 with screws 54. And the other end side of the axial direction of the 1st-3rd heaters 43-45 is attached to the sheet metal which is not illustrated.

  As described above, the heat reflecting member 55 is held by the holding member 52 by contacting the flat portion 52b of the holding member 52 and engaging the locking portion 52e. Thus, the heat reflecting surface 55a faces the direction perpendicular to the axial direction of the heat roller 18 in the heat roller 18, and is disposed toward the first to third heaters 43 to 45.

  Further, the heat reflecting surface 55a is arranged as shown in FIG. 9 with respect to the heat roller 18 and the first to third heaters 43 to 45. With this arrangement, the circumferential surface of the heat roller 18 is heated by being assigned approximately equally to the heaters 43 to 45 that are arranged in three equal parts on the circumference, and reaches a predetermined temperature. However, in the central portion surrounded by the first to third heaters 43 to 45, the heat heated by the first to third heaters 43 to 45 is concentrated, so that the central portion is more extreme than the peripheral surface of the heat roller 18. It is very hot. Therefore, even if the holding member 52 is formed of a heat-resistant material, the portion corresponding to the central portion is overheated by the heat radiation of the first to third heaters 43 to 45, and may be thermally deformed. Therefore, the heat reflection surface 55a is disposed at a position corresponding to the substantially central portion surrounded by the first to third heaters 43 to 45, so that the first to third heaters 43 to 45 are directed toward the holding member 52. The reflected heat is reflected, heat transfer to the holding member 52 can be suppressed, and thermal deformation of the holding member 52 can be prevented.

  According to the first embodiment, the fixing device 5 includes the heat roller 18 including the first to third heaters 43 to 45 for heating the toner image on the paper 9, and the heat roller 18. An apparatus housing 50 that holds the heat roller 18 at both ends in the axial direction, and a heat reflecting surface 55a disposed on the end side in the axial direction inside the heat roller 18 are provided.

  According to this configuration, the first to third heaters 43 to 45 dissipate heat in the circumferential direction in the heat roller 18 to heat the heat roller 18, and the heat of the heat roller 18 heats and fixes the toner image to the paper 9. Is done. Further, the first to third heaters 43 to 45 radiate heat in the axial direction in the heat roller 18, but this heat is reflected by the heat reflecting surface 55 a and is transferred to the device housing 50 corresponding to the inside of the heat roller 18. Therefore, the temperature rise of the apparatus housing can be suppressed with a simple configuration, and thermal deformation of the apparatus housing can be prevented.

  Further, according to the first embodiment, the first to third heaters 43 to 45 are arranged side by side in the axial direction, and the heat reflecting surface 55a is arranged at a position corresponding to between the first to third heaters 43 to 45. Set up. When the first to third heaters 43 to 45 are arranged side by side in the axial direction, the heat distribution is such that the temperature between the first to third heaters 43 to 45 is higher than the peripheral surface of the heat roller 18. By disposing the heat reflecting surface 55a at a position corresponding to between the third heaters 43 to 45, overheating of the apparatus housing can be efficiently suppressed, and thermal deformation of the apparatus housing can be prevented.

  Further, according to the first embodiment, the apparatus housing 50 includes the upper housing 51 (housing) and the holding member 52 attached to the upper housing 51, and the holding member 52 includes the heat reflecting surface 55a and the heat reflecting surface 55a. First to third heaters 43 to 45 are provided. As a result, the heat reflecting surface 55a and the first to third heaters 43 to 45 are attached to the holding member 52, and then the holding member 52 is attached to the upper housing 51, so that the heat reflecting surface 55a and the first to first heaters are attached. The three heaters 43 to 45 can be easily assembled. Moreover, since the upper housing | casing 51 and the holding member 52 are provided separately, a material can be suitably selected according to the heat resistance and intensity | strength characteristic required for each member.

  In addition, according to the first embodiment, the heat reflecting surface 55a is formed on the heat reflecting member 55 made of a metal plate, so that the heat reflecting surface 55a can use the gloss of the metal plate. The heat reflecting surface can be formed with a simple member without performing the above process.

  Further, according to the first embodiment, the pressure roller 19 that is in pressure contact with the heat roller 18 is provided, and the toner image on the paper 9 is heat-fixed at the nip portion N where the heat roller 18 and the pressure roller 19 are in pressure contact. In addition, the temperature rise of the device housing 50 corresponding to the inside of the heat roller 18 is suppressed by the heat reflecting surface 55a disposed on the end side in the axial direction inside the heat roller 18, and the device housing It can prevent thermal deformation of the body.

  In addition, although the structure which forms the heat | fever reflective surface 55a in a metal plate was shown in the said 1st Embodiment, this invention is not limited to this, The heat insulation layer which can be thermally reflected is coated in the opposing part 52a of the holding member 52. You may do it.

(Second Embodiment)
FIG. 10 is a diagram showing a schematic configuration of a fixing device used in an image forming apparatus according to the second embodiment of the present invention. FIG. 11 is a partial cross-sectional side view showing a holding member to which a heater and a heat reflecting member used in the fixing device are attached. Different from the first embodiment, the heat reflection member that also serves as a fixing method and an electrical connection terminal will be mainly described, and the description of the same parts as those of the first embodiment will be omitted hereinafter.

  As shown in FIG. 10, the fixing device is a belt fixing system, and includes a fixing belt 232, a fixing roller 233, a pressure roller 219, a heat roller 218, a plurality of heaters 243 to 245 as heat sources, and a motor. And a drive source 249 having a reduction gear.

  The heat roller 218 has a cylindrical cored bar made of a metal such as aluminum or iron having excellent thermal conductivity, and the cored bar is coated with a fluororesin coating or a tube. Three heaters 243 to 245 such as halogen lamps are provided inside the core of the heat roller 218.

  The plurality of heaters 243 to 245 are arranged at a position equally divided by three in the circumference of the heat roller 218 and at a substantially equal distance from the circumferential surface of the heat roller 218. The plurality of heaters 243 to 245 have different heat distributions in the axial direction of the heat roller 218. For example, the heater 243 has a small amount of heat distribution at one end in the axial direction compared to other parts, the heater 244 has a large amount of heat distribution at one end compared to other parts, and the heater 245 has other parts at the center. It has a heat distribution with a large amount of heat distribution compared to the part.

  The fixing belt 232 is an endless belt formed of a nickel thin plate, and an outer peripheral surface is coated with an offset preventing agent such as a silicon rubber film.

  The fixing roller 233 includes sponge rubber on a cylindrical base material, and gives elasticity to the nip portion N. The fixing roller 233 is rotatably supported and stretches the fixing belt 232 together with the heat roller 218. Heat from the plurality of heaters 243 to 245 disposed in the heat roller 218 is transmitted to the fixing belt 232 via the heat roller 218, and the fixing belt 232 is heated.

  The pressure roller 219 is a resin in which an elastic layer such as silicon rubber is formed on a cylindrical base material made of synthetic resin, metal or other material, and the surface of the elastic layer is excellent in releasability such as fluororesin. The one covered with is used. When the pressure roller 219 is pressed toward the center of the fixing roller 233 via the fixing belt 232, a nip portion N is formed between the pressure roller 219 and the fixing belt 232.

  The drive source 249 is gear-connected to the pressure roller 219 and transmits the driving force from the motor to the pressure roller 219 via the gear. When the motor is driven to rotate, the pressure roller 219 rotates in the direction of the arrow in FIG. With the rotation of the pressure roller 219, the fixing roller 233 and the fixing belt 232 that are in pressure contact with the pressure roller 219 rotate at the same speed in the direction of the arrow in FIG. 10, and the heat roller 218 is rotated by the fixing belt 232.

  The sheet 9 conveyed to the nip portion N is heated and pressed by the fixing belt 232 and the pressure roller 219, whereby the powdery toner on the sheet 9 is heated and fixed. Further, due to the rotation of the fixing belt 232 and the pressure roller 219, the fixed sheet 9 is separated from the heat roller 218 and conveyed upward in FIG.

  Next, the structure of the heat | fever reflection member attached to a holding member is demonstrated using FIG.

  The holding member 252 is formed of a resin having heat resistance such as a liquid crystal polymer, and includes a flat portion 252b, a facing portion 252a, and a lower portion 252e. The flat portion 252b, the facing portion 252a, and the lower portion 252e are formed in a U-shaped cross section. The facing portion 252a has a surface that expands in a direction orthogonal to the axial direction of the plurality of heaters 243 to 245.

  A connection terminal member 257 having an L-shaped cross section abuts against the flat portion 252b and the facing portion 252a. The connection terminal member 257 electrically connects the heater and reflects heat radiated from the heater. Therefore, the connection terminal member 257 is formed of a material such as a stainless steel plate or an aluminum plate that has conductivity, is glossy, reflects radiant heat, and has a relatively high thermal conductivity.

  The heater 243 includes a glass tube containing a tungsten filament and enclosing a halogen gas, and a lead wire 243a protruding from an end of the glass tube. The lead wire 243a of the heater 243 is crimped and soldered to the flat terminal portion 246.

  A terminal portion 246 of the heater 243 is in contact with the connection terminal member 257. A nut 258 having a screw hole is disposed in a gap formed by the flat portion 252b, the facing portion 252a, and the lower portion 252e of the holding member 252. The screw 259 is inserted into the hole of the terminal portion 246 of the heater 243, the hole of the connection terminal member 257, and the long hole portion 252c formed in the flat surface portion 252b, and the screw 259 is screwed into the screw hole of the nut 258. Accordingly, the terminal portion 246 of the heater 243 is attached to the connection terminal member 257, the heater 243 and the connection terminal member 257 can be energized, and the connection terminal member 257 is attached to the holding member 252. The other heaters 244 and 245 are directly attached to the holding member 252 in the same manner as the attachment of the second heater 44 and the third heater 45 of the first embodiment.

  When the connection terminal member 257 is attached to the holding member 252, the heat reflecting surface 257 a faces the surface in a direction perpendicular to the axial direction of the plurality of heaters 243 to 245 and is surrounded by the plurality of heaters 243 to 245. It will be arranged at a position corresponding to the substantially central portion. As a result, the heat reflecting surface 257c reflects the heat radiated from the plurality of heaters 243 to 245 toward the holding member 252, suppressing heat transfer to the holding member 252, and preventing the heat deformation of the holding member 252. .

  According to the second embodiment, the fixing device 5 includes the heat roller 218 including a plurality of heaters 243 to 245 for heating the toner image on the paper 9, and the axial direction of the heat roller 218. An apparatus housing that holds the heat roller 218 at both ends, a heat reflection surface 257a disposed on the end side in the axial direction inside the heat roller 218, and connected to a terminal portion 246 provided on the heater 243. Connecting terminal member 257 (metal plate).

  According to this configuration, the plurality of heaters 243 to 245 dissipate heat in the circumferential direction in the heat roller 218, whereby the heat roller 218 is heated and the toner image is heated and fixed on the paper 9 by the heat of the heat roller 218. Further, the plurality of heaters 243 to 245 radiate heat in the axial direction in the heat roller 218, but this heat is reflected by the heat reflecting surface 257a and is prevented from being transmitted to the corresponding device housing inside the heat roller 218. Therefore, with a simple configuration, the temperature rise of the apparatus housing can be suppressed, and thermal deformation of the apparatus housing can be prevented. Further, since the connection terminal member 257 has both the connection terminal electrically connected to the heater and the heat reflecting surface 257a, the assembly can be simplified and the apparatus can be downsized.

  Further, according to the second embodiment, the endless fixing belt 232 is stretched between the heat roller 218 and the fixing roller 233, and the pressure roller 219 is pressed against the fixing roller 233 via the fixing belt 232. The toner image on the sheet 9 can be heat-fixed at the nip portion N where the fixing belt 232 and the pressure roller 219 are in pressure contact, and the heat roller 218 is disposed on the end side in the axial direction inside the heat roller 218. By the reflection surface 257a, the temperature rise of the apparatus housing corresponding to the inside of the heat roller 218 can be suppressed, and thermal deformation of the apparatus housing can be prevented.

  In the first and second embodiments, the heater and the heat reflecting surface are attached to the holding member and the holding member is attached to the upper housing. However, the present invention is not limited to this, and the heater and the heat reflecting surface are attached. You may make it the structure which attaches a reflective surface to an upper side housing | casing. In this case, the same effect as described above is obtained.

  In the first and second embodiments, an example in which three heaters are arranged as a plurality of heaters has been described. However, the present invention is not limited to this, and two heaters are arranged. In other words, the heat reflecting surface may be arranged on the end side in the corresponding axial direction between the two heaters. In the case where one heater is provided, the heat reflecting surface may be arranged on the end side in the axial direction corresponding to the periphery of the heater. Furthermore, a heat reflecting surface may be provided on the entire surface of the opposing portion of the holding member to suppress an increase in the temperature of the apparatus housing in a wide range inside the heat roller.

  INDUSTRIAL APPLICABILITY The present invention can be used for a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using the electrophotographic method, and an image forming apparatus including the fixing device. The present invention can be used in a fixing device built in a roller and an image forming apparatus including the fixing device.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Fixing device 18, 218 Heat roller 18a Mounting shaft 19, 219 Pressure roller 43-45, 243-245 Heater 43a-45a Lead wire 46-48, 246 Terminal part 50 Device case 51 Upper case ( Housing)
51a Opening portion 52, 252 Holding member 52a, 252a Opposing portion 52b, 252b Plane portion 52c, 252c Long hole portion 52d Protrusion portion 52e Locking portion 52f Cavity portion 52g Opening portion 53 Lower casing 54, 59, 259 Screw 55 Heat Reflective member 55a, 257a Heat reflecting surface 55b, 55e Mounting portion 55c Mounting hole 55d Notch 55g Screw mounting hole 257 Connection terminal member (metal plate)
58, 258 Nut 232 Fixing belt 233 Fixing roller N Nip part

Claims (8)

  A heat roller having a built-in heater for heating the toner image on the paper, an apparatus housing for holding the heat roller at both axial ends of the heat roller, and an axial direction inside the heat roller And a heat reflecting surface disposed on the end side of the fixing device.   The fixing device according to claim 1, wherein a plurality of the heaters are arranged side by side in the axial direction, and the heat reflecting surface is disposed at a position corresponding to the space between the plurality of heaters.   The said apparatus housing | casing has a housing | casing and the holding member attached to this housing | casing, The said heat reflection surface and the said heater are provided in the said holding member, The Claim 1 or Claim 2 characterized by the above-mentioned. Fixing device.   The fixing device according to claim 1, wherein the heat reflecting surface is formed on a metal plate.   The fixing device according to claim 4, wherein the metal plate has a connection terminal portion connected to a terminal portion provided in the heater.   6. The toner image on a sheet is heat-fixed at a nip portion between the heat roller and the pressure roller, wherein the toner image on the sheet is heated and fixed. A fixing device according to claim 1.   An endless fixing belt is stretched between the heat roller and the fixing roller, and includes a pressure roller that presses against the fixing roller via the fixing belt, and a nip portion that presses the fixing belt and the pressure roller; 6. The fixing device according to claim 1, wherein the toner image on the sheet is fixed by heating.   An image forming apparatus on which the fixing device according to claim 1 is mounted.

Images