JP5504186B2 - FIXING DEVICE, IMAGE FORMING DEVICE EQUIPPED WITH THE FIXING DEVICE, AND METHOD FOR MANUFACTURING FIXING DEVICE - Google Patents

Description

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

  2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines and printers, fixing devices that fix a toner image carried on a recording medium to the recording medium by heating and pressurizing are widely used. With the recent increase in awareness of energy saving, there is a demand for lower power consumption of image forming apparatuses, and in particular, there is a particular demand for higher efficiency of fixing devices that consume more power in the image forming apparatus.

  Specifically, the fixing device includes a fixing roller and a pressure roller, the fixing roller includes a heat source such as a halogen lamp, and is attached in a state where the pressure roller is in pressure contact with the fixing roller. The toner image carried on the recording medium is thermally melted and fixed on the recording medium when the recording medium passes through the nip portion between the fixing roller and the pressure roller. It has become important to prevent the heat generated from such a fixing device from flowing out of the fixing device. In order to suppress heat divergence from the fixing roller and to suppress heat transfer to the outside of the fixing device, a heat insulating cover is provided along the outer periphery of the fixing roller to constitute the heat insulating cover and the outer frame of the device. A void portion surrounded by and is formed so that the air layer in the void portion has a heat insulating effect.

  In order to secure a high heat insulation effect and to make a fixing device that is low-cost and easy to manufacture, in Patent Document 1, a foam material containing a resin and a foaming agent is placed in the gap, and this is foamed in the gap. A resin foam is formed in the gap.

Japanese Patent Laid-Open No. 10-10890 (paragraph [0006], FIG. 1)

  In Patent Document 1 described above, if the resin foam formed in the gap portion has a variation in the foaming size, or a variation in the foamed state due to a variation in the ratio between the closed cells and the open cells, the heat insulation performance is in the paper passing region. In addition, the heat insulation effect becomes unstable because individual differences occur in fixing devices incorporating such a resin foam. In addition, when printing a recording medium having a width smaller than the maximum width of the recording medium to be fixed, a temperature difference occurs between the sheet passing area and the non-sheet passing area. In the configuration having the effect, heat transfer to the outside of the apparatus is also suppressed in the non-sheet passing area, and the non-sheet passing area is excessively heated.

  The present invention has been made in order to solve the above-described problems, and prevents heat from flowing out of the apparatus to improve heat insulation performance, and continuously performs fixing processing of a recording medium having a small width. Of the fixing device that eliminates the temperature difference generated between the paper passing area and the non-paper passing area, and can be easily manufactured at low cost, and an image forming apparatus and a fixing device provided with the fixing device. An object is to provide a manufacturing method.

  In order to achieve the above object, the first invention has a fixing roller heated by a heating means, and a pressure roller pressed against the fixing roller, and the fixing roller and the pressure roller are pressed against each other. In a fixing device for fixing a toner image carried on a recording medium to a recording medium at a nip portion to be disposed, a part of an outer peripheral surface of at least one of the fixing roller or the pressure roller is arranged at a predetermined interval. An outer peripheral surface in the radial direction of the at least one roller, a heat insulating cover that is disposed outside the heat insulating cover, constitutes an outer frame of the apparatus, and forms a gap between the heat insulating cover and the heat insulating cover. And a plurality of cylindrical hollow members filled in the gap so as to contact each other.

  According to a second aspect of the present invention, in the above fixing device, the plurality of hollow members are filled so that both end portions are in contact with inner walls of the gap portion in the roller axial direction.

  According to a third aspect of the present invention, in the fixing device, the gap is formed at a first gap corresponding to a paper passing area having a width smaller than the maximum width of the paper passing area and at both ends in the roller axis direction. The first gap member is divided into a second gap portion corresponding to the non-sheet passing area, and the second gap portion includes a first opening / closing member that opens and closes one of the both end sides in the roller axis direction, and has a small width recording. When the medium passes through the nip portion, the first opening / closing member opens the second gap portion.

  According to a fourth aspect of the present invention, in the above fixing device, the second opening / closing member capable of opening / closing the other of the both ends of the second gap portion and air from one of the second gap portions to the other. A blower member capable of blowing air, and when the narrow recording medium is passed through the nip portion, the first and second opening / closing members open both ends of the second gap portion, and The blowing member is characterized in that air is sent from one of the second gaps to the other.

  According to a fifth aspect of the present invention, in the above fixing device, the hollow member is formed of an elastic material.

  According to a sixth aspect of the present invention, in the above fixing device, the gap is formed at the first gap corresponding to a paper passing area having a width smaller than the maximum width of the paper passing area and at both ends in the roller axis direction. The plurality of hollow members that are divided into second gap portions corresponding to the non-sheet-passing areas and provided in the second gap portions are elastically deformable, and the second gap portions are A movable frame that constitutes a part of the outer wall of the frame and is reciprocally movable in the roller radial direction, and when the small-width recording medium is passed through the nip portion, the movable frame is When the second gap is compressed and the plurality of hollow members are crushed by being arranged at the first position closest to the roller, the maximum width of the recording medium is passed through the nip. The movable frame is arranged at the second position farthest from the one roller. In Rukoto, the plurality of hollow members the second gap portion is extended is characterized in that to restore the original state.

  In the seventh invention, in the fixing device, the heat insulating cover is characterized in that a surface facing the outer peripheral surface of the at least one roller is a reflecting surface.

  According to an eighth aspect of the present invention, in the fixing device, the heat insulating cover and the frame are arranged at a predetermined distance from at least an outer peripheral surface of the fixing roller.

  According to a ninth aspect of the invention, there is provided an image forming apparatus including the fixing device having the above-described configuration.

  According to a tenth aspect of the present invention, there is provided a heat insulating cover disposed at a predetermined distance from a part of an outer peripheral surface of at least one of the fixing roller and the pressure roller, and disposed outside the heat insulating cover. A frame that forms a frame and forms a space between the heat insulating cover and a plurality of cylindrical hollows that are filled in the space so that outer peripheral surfaces abut each other in the radial direction of the at least one roller A fixing device comprising: a member; and forming a molten adhesive layer on an outer peripheral surface of the plurality of hollow members, and filling the gap with the plurality of hollow members formed with the molten adhesive layer, It is characterized by being left for a predetermined time at a temperature equal to or higher than the melting point of the molten adhesive layer.

  The eleventh aspect of the present invention is a heat insulating cover disposed at a predetermined distance from a part of the outer peripheral surface of at least one of the fixing roller or the pressure roller, and disposed outside the heat insulating cover. A frame that forms a frame and forms a space between the heat insulating cover and a plurality of cylindrical hollows that are filled in the space so that outer peripheral surfaces abut each other in the radial direction of the at least one roller A plurality of hollow members are bundled with a film, and the plurality of bundled hollow members are filled in the gap portion.

  In a twelfth aspect of the invention, in the method for manufacturing a fixing device, the film covers both end surfaces of the plurality of hollow members.

  According to the first invention, the plurality of hollow members are filled in the gap so that the outer peripheral surfaces thereof are in contact with each other in the roller radial direction, whereby the air layer flows in the roller radial direction and the roller circumferential direction. Stays. Therefore, the heat in the apparatus can be prevented from flowing to the outside, and the heat insulation performance can be improved. Further, in the fixing process of the recording medium having a small width, convection due to the temperature difference in the roller axial direction is generated in the hollow portion of the hollow member corresponding to the temperature difference between the sheet passing area and the non-sheet passing area. A temperature difference generated between the paper passing area and the non-paper passing area can be eliminated.

  According to the tenth invention, after filling the hollow portion with a plurality of hollow members, the adhesive layer of the melt adhesive layer is melted by leaving it at a temperature equal to or higher than the melting point of the melt adhesive layer for a predetermined time, The plurality of hollow members are fixed to each other by the melted adhesive layer, and are fixed to the inner wall of the gap by the melted adhesive layer. Therefore, a plurality of hollow members can be easily filled in the gap at low cost.

  In addition, according to the eleventh invention, it is possible to enhance the heat insulating performance by simply bundling a plurality of hollow members with a film and filling the plurality of bundled hollow members into a gap portion, and a plurality of hollow members. Is easily filled in the gap.

1 is a diagram illustrating a schematic configuration of an image forming apparatus including a fixing device according to a first embodiment of the present invention. 1 is a side sectional view showing a fixing device according to a first embodiment. FIG. 3 is a cross-sectional plan view showing the main part of the fixing device according to the first embodiment. Side surface sectional drawing of the hollow member used for the fixing device which concerns on 1st Embodiment. Plan sectional drawing which shows the principal part of the fixing device which concerns on 2nd Embodiment. FIG. 10 is a cross-sectional plan view illustrating a main part of the fixing device according to the second embodiment when fixing a sheet having a small width. Plan sectional drawing which shows the principal part of the fixing device which concerns on 3rd Embodiment. FIG. 9 is a cross-sectional plan view illustrating a main part of a fixing device according to a third embodiment when fixing a sheet having a small width. The top view which shows the hollow member of the fixing device which concerns on 4th Embodiment. The top view which shows the modification of the film which bundles the hollow member which concerns on 4th Embodiment

  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 including a fixing device according to an embodiment of the present invention. The image forming apparatus 1 includes a sheet feeding unit 2 disposed in a lower portion thereof, a sheet conveying unit 3 disposed on the right side of the sheet feeding unit 2, and an image disposed on the upper side of the sheet conveying unit 3. The image forming unit 4 includes a forming unit 4, a fixing device 5 disposed on the discharge side of the image forming unit 4, and an image reading unit 6 disposed on the upper side of the image forming unit 4 and the fixing device 5.

  The paper feed unit 2 includes a plurality of paper feed cassettes 7 that store paper 9 that is a recording medium. The paper 9 is sent to the paper transport unit 3 one by one.

  The paper 9 sent to the paper transport unit 3 is transported toward the image forming unit 4 via the paper transport path 10. The image forming unit 4 forms a toner image on the paper 9 by an electrophotographic process, and a photosensitive member 11 that can rotate in the direction of an arrow, and a charging device around the photosensitive member 11 along the rotating direction. A unit 12, an exposure unit 13, a developing device 14, a transfer unit 15, a cleaning unit 16, and a charge removal unit 17.

  The charging unit 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, when 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 unit 13, the surface potential of the photoconductor 11 is selectively attenuated, and the surface of the photoconductor 11 is irradiated. An electrostatic latent image is formed.

  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 unit 15 to the paper 9 supplied between the photoconductor 11 and the transfer unit 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 fixing roller 18 and the pressure roller 19, and the toner image is melted and 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 unit 15, the toner remaining on the surface of the photoconductor 11 is removed by the cleaning unit 16, and the residual charge on the surface of the photoconductor 11 is removed by the charge eliminating unit 17. Then, the photosensitive member 11 is charged again by the charging unit 12, and image formation is performed in the same manner.

  FIG. 2 is a side sectional view showing a schematic configuration of the fixing device 5 used in the above-described image forming apparatus 1, and FIG. 3 is a sectional plan view showing a main part of the fixing device 5. The roller axial direction of the fixing roller 18 is the X direction, and the roller radial direction of the fixing roller 18 is the Y direction.

  As shown in FIG. 2, the fixing device 5 is a roller fixing system, and includes a fixing roller 18, a pressure roller 19, a heater 43 that is a heating unit, a lower frame body 55, an upper frame body 56, Insulating covers 57 and 58 and a hollow member 61 are provided.

  As the fixing roller 18, a cylindrical cored bar made of a metal such as aluminum or iron having excellent thermal conductivity is coated with a fluororesin coating or a tube. A heater 43 such as a halogen lamp or a xenon lamp is provided inside the cored bar of the fixing roller 18.

  The pressure roller 19 is formed by forming an elastic layer such as silicon rubber on a cylindrical base material made of synthetic resin, metal or other material, and coating the surface of this elastic layer with a fluororesin coat. .

  Further, when the pressure roller 19 is brought into pressure contact with the fixing roller 18 at a predetermined pressure and the pressure roller 19 is rotationally driven, the fixing roller 18 is driven to rotate. A nip portion N is formed at a portion where the fixing roller 18 and the pressure roller 19 come into contact with each other while rotating in reverse.

  The lower frame 55 forms a part of the outer frame of the fixing device 5 in a semicircular shape, and supports the pressure roller 19 to be rotatable in the roller axial direction X. Further, an upstream conveyance guide 40 and a downstream conveyance guide 41 are attached to the lower frame 55 so as to face the pressure roller 19, respectively. The upstream conveyance guide 40 guides the sheet 9 to the nip N, and the downstream conveyance guide 41 guides the sheet 9 fixed at the nip N to a predetermined position outside the fixing device 5. is there.

  The heat insulating cover 58 prevents the heat of the pressure roller 19 from being released to the outside of the apparatus, and is formed of aluminum in a circular arc shape when viewed from the side along the lower outer periphery of the pressure roller 19. Is done. The heat insulating cover 58 is attached to the upper part of the lower frame 55 with a predetermined distance from the pressure roller 19 and surrounds the lower frame 55 to form a semi-cylindrical gap S. Note that the heat insulating cover 58 may be formed of resin and aluminum may be deposited on the surface facing the pressure roller 19. The surface of the heat insulating cover 58 that faces the pressure roller 19 is formed of an aluminum reflecting surface, so that the infrared radiation emitted from the pressure roller 19 is reflected by the heat insulating cover 58 and the temperature of the lower frame 55 increases. Can be suppressed, and the heat insulation is improved.

  The upper frame 56 forms a part of the outer frame of the fixing device 5 in a semicircular shape, and supports the fixing roller 18 so as to be rotatable in the roller axial direction X. A separation claw (not shown) is attached to the upper frame 56, and the separation claw separates the paper 9 after the fixing process from the surface of the fixing roller 18.

  The sheet 9 is guided by the conveyance guide 40 and is conveyed to the nip portion N, and the toner in the powder state on the sheet 9 is heated and pressed by the fixing roller 18 and the pressure roller 19 in the nip portion N. Is melted and fixed. The sheet 9 after the fixing process is separated from the surface of the fixing roller 18 by the separation claw, and then guided to a predetermined position outside the fixing device 5 by the downstream side conveyance guide 41. Further, when a small size paper or A4 vertical paper is passed through the nip portion N, a narrow paper passing region is formed in the central portion in the roller axial direction X, while non-passage is formed in both sides in the roller axial direction X. A sheet passing area is formed and heated and pressed by the fixing roller 18 and the pressure roller 19, whereby the powdered toner on the sheet 9 is thermally melted and fixed.

  The heat insulating cover 57 prevents the heat of the fixing roller 18 from being released to the outside of the apparatus, and is formed of aluminum in a circular arc shape when viewed from the side so as to follow the outer periphery on the upper side of the fixing roller 18. The heat insulating cover 57 is attached to the lower part of the upper frame body 56 with a predetermined distance from the fixing roller 18, and surrounds the upper frame body 56 to form the gap S. The heat insulating cover 57 may be formed of a resin so that aluminum is deposited on the surface facing the fixing roller 18. The heat insulating cover 57 is configured such that the surface facing the fixing roller 18 is an aluminum reflecting surface, so that the infrared radiation emitted from the fixing roller 18 is reflected by the heat insulating cover 57 and suppresses the temperature rise of the upper frame 56. And heat insulation is improved.

  The gap S is formed in a semi-cylindrical shape facing the fixing roller 18 and extends longer than the fixing roller 18 in the roller axial direction X (see FIG. 3). In the gap S, a plurality of hollow members 61 are provided.

  The plurality of hollow members 61 are provided such that the outer peripheral surfaces of the hollow members 61 are in contact with each other so as to fill the space from the upper wall portion 56b of the upper frame 56 to the heat insulating cover 57 in the roller radial direction Y of the gap portion S. In addition, it extends in the roller axial direction X and is provided in contact with the side wall portions 56a (see FIG. 3) on both sides of the upper frame 56.

  The hollow member 61 has a cross-sectional configuration shown in FIG. FIG. 4 is a side sectional view of the hollow member 61. The hollow member 61 is formed in a cylindrical shape having a hollow portion 61a of a heat-resistant and elastic resin material such as polyimide resin, polyamide resin, silicon, or fluororesin. The diameter of the hollow portion 61a is 1 to 2 mm, and the thickness T of the hollow member 61 is desirably 0.5 mm or less. When the hollow member 61 is in this range, good heat insulation is obtained and the hollow member 61 is hollow. Air convection is likely to occur in the portion 61a.

  On the outer peripheral surface of the hollow member 61, a molten adhesive layer 62 is formed in which the adhesive layer melts when heated to the melting point or higher. The molten adhesive layer 62 is made of a material that melts the adhesive layer when heated to the melting point or higher.

  After housing the plurality of hollow members 61 in the upper frame 56, the heat insulating cover 57 is attached to the upper frame 56. That is, after incorporating the plurality of hollow members 61 into the gap S, the upper frame body 56 is left in a high-temperature tank set at a temperature equal to or higher than the melting point of the molten adhesive layer 62 for a predetermined time. Accordingly, the plurality of hollow members 61 are fixed to each other by the melted molten adhesive layer 62, and are also fixed to the inner wall of the gap S by the melted molten adhesive layer 62. By adopting such a manufacturing method, the plurality of hollow members 61 can be filled in the gap S easily at low cost.

  According to the first embodiment, the fixing device 5 includes the heat insulating cover 57 disposed at a predetermined distance from a part of the outer peripheral surface of the fixing roller 18, and the heat insulating cover 57 disposed outside the heat insulating cover 57. An upper frame 56 forming a gap S between the frame and the heat insulating cover 57, and a plurality of cylindrical hollow members filled in the gap S so that the outer peripheral surfaces abut each other in the roller radial direction Y 61.

  According to this configuration, the plurality of hollow members 61 are filled in the gap S so that the outer peripheral surfaces thereof are in contact with each other in the roller radial direction Y, so that in the roller radial direction Y and the roller circumferential direction, the air layer The stream stays. Therefore, it is possible to prevent heat from flowing out of the apparatus and improve the heat insulation performance.

  Usually, when a sheet having a width smaller than the maximum width of the sheet to be subjected to the fixing process is fixed, a temperature difference occurs between the sheet passing area and the non-sheet passing area. However, according to the above configuration, in the fixing process of the small-width paper 9, the hollow portions 61a of the plurality of hollow members 61 are arranged in the roller axial direction in accordance with the temperature difference between the paper passing area and the non-paper passing area. Since the convection due to the temperature difference of X occurs, the temperature difference generated between the paper passing area and the non-paper passing area can be eliminated.

  Further, according to the first embodiment, the plurality of hollow members 61 are filled in contact with the side wall portion 56a of the upper frame body 56 (the inner wall of the gap portion S in the roller axial direction X).

  According to this configuration, the hollow portion 61a of the hollow member 61 is sealed by the end surface of the hollow member 61 and the side wall portion 56a of the upper frame body 56, and there is no possibility that air leaks from the hollow portion 61a. The heat insulating property of S is further improved.

  Moreover, according to the said 1st Embodiment, the some hollow member 61 is formed with an elastic material.

  According to this configuration, if the hollow member 61 is set to be slightly longer than the predetermined length in the roller axial direction X, even if the length of the hollow member 61 varies, the hollow member 61 is elastically deformed and the hollow member 61 is deformed. It becomes possible to abut the end surface of this and the side wall portion 56a of the upper frame body 56. The hollow portion 61a of the hollow member 61 is sealed by the end face of the hollow member 61 and the side wall portion 56a of the upper frame body 56, and there is no risk of air leaking from the hollow portion 61a, so that the heat insulation of the gap portion S is maintained. can do.

  A plurality of hollow members 61 are also provided in the gap S (the pressure roller 19 side) formed by the lower frame 55 and the heat insulating cover 58 shown in FIG. Since the hollow member 61 is assembled with the same configuration and arrangement as the plurality of hollow members 61 on the fixing roller 18 side, the same effect as the plurality of hollow members 61 on the fixing roller 18 side is exhibited.

(Second Embodiment)
FIG. 5 is a plan sectional view showing an upper frame body incorporating a hollow member according to the second embodiment, and FIG. 6 is a plan sectional view showing the upper frame body when a paper having a small width is fixed. . The second embodiment is different from the first embodiment in that the gap portion is divided and the opening / closing member and the air blowing member are further provided. The description of the same part is omitted.

  As shown in FIG. 5, the upper frame body is provided on the both ends of the first frame body 74 and the first frame body 74 in the roller axial direction X by partitioning with the wall portions constituting the upper frame body. A pair of second frames 75 are divided. The first frame 74 is provided with a width TA in the roller axial direction X corresponding to the paper passing area of the paper 9 with a small width, and the second frame 75 is a non-passage of the paper 9 with a small width. It is provided with a width TB in the roller axial direction X corresponding to the paper region.

  The heat insulating cover 78 prevents the heat of the fixing roller 18 (see FIG. 2) from being released to the outside of the apparatus, and the first frame 74 and the fixing roller 18 are spaced apart from each other by a predetermined distance. It is attached to the lower part of each of the second frame bodies 75. A space S1 is formed in a space surrounded by the first frame 74 and the heat insulating cover 78, and a space S2 is formed in a space surrounded by the second frame 75 and the heat insulating cover 78. Instead of providing the heat insulating cover 78 separately for the first frame 74 and the second frame 75, the heat insulating cover 78 is integrated with the first frame 74 and the second frame 75, respectively. May be provided.

  A plurality of first hollow members 71 are provided in the gap portion S1, and a plurality of second hollow members 72 are provided in the pair of gap portions S2.

  The plurality of first hollow members 71 are provided so that the outer peripheral surfaces thereof are in contact with each other in the roller radial direction Y of the gap S1, and extend in the roller axial direction X of the gap S1 on the side wall portions on both sides of the gap S1. It is provided in contact. On the other hand, the plurality of second hollow members 72 are provided such that the outer peripheral surfaces are in contact with each other in the roller radial direction Y of the gap portion S2, and extend in the roller axial direction X of the gap portion S2. It is provided in contact with the part. A fusion bonding layer 62 (see FIG. 4) is formed on each outer peripheral surface of the first and second first hollow members 71 and 72, and a plurality of first and second hollows are formed as in the first embodiment. The members 71 and 72 are filled in the gaps S1 and S2, respectively.

  An outer opening / closing member 76 and an inner opening / closing member 77 are provided at both ends of the second frame 75 in the roller axial direction X. The outer opening / closing member 76 constitutes the outer wall of the second frame 75 and is provided so as to be movable in the roller radial direction Y. On the other hand, the inner opening / closing member 77 constitutes the inner wall of the second frame 75 and is provided so as to be movable in the roller radial direction Y. The outer opening / closing member 76 and the inner opening / closing member 77 may be configured to be movable in the transport direction of the paper 9.

  When fixing the sheet 9 having the maximum width capable of passing paper, the outer opening / closing member 76 and the inner opening / closing member 77 are closed, so that each hollow portion of the plurality of second hollow members 72 is formed in the gap portion S2. An air layer is formed, and the flow of the air layer stays in the roller radial direction Y and the roller circumferential direction. Therefore, heat can be prevented from flowing out of the apparatus in the gap S2 together with the gap S1, and the heat insulation performance can be enhanced over the entire widths TA and TB.

  As shown in FIG. 6, when fixing a sheet 9 having a width smaller than the maximum width, the outer opening / closing member 76 and the inner opening / closing member 77 are opened, and the air gap S2 is opened to the outside. 79 sends air from the outer opening / closing member 76 side to the inner opening / closing member 77 side.

  With this configuration, an air flow indicated by an arrow is generated in the gap S2, and the heat of the gap S2 is diffused, so that the width TB corresponding to the non-sheet passing area and the width TA corresponding to the sheet passing area are between. The temperature difference that occurs in can be eliminated.

  When fixing the sheet 9 having a width smaller than the maximum width, instead of the above-described embodiment, the configuration is such that one of the outer opening / closing member 76 and the inner opening / closing member 77 is opened without driving the air blowing member 79. It may be. In this configuration, air convection is generated by the temperature difference between the gap S2 and the open outside air, and the heat in the gap S2 is diffused, so that the width TB corresponding to the non-sheet passing region and the sheet passing It is possible to eliminate the temperature difference that occurs between the width TA corresponding to the region.

(Third embodiment)
FIG. 7 is a plan cross-sectional view showing an upper frame body incorporating a hollow member according to the third embodiment, and FIG. 8 is a plan cross-sectional view showing the upper frame body when fixing a sheet having a small width. . The third embodiment is different from the second embodiment in that a movable frame and a cam member are provided instead of the opening / closing member and the air blowing member.

  As shown in FIG. 7, the upper frame body is provided on both ends of the first frame body 74 and the first frame body 74 in the roller axial direction X by partitioning with a wall portion constituting the upper frame body. A pair of second frames 81 are divided. The first frame 74 is provided with a width TA in the roller axial direction X corresponding to the paper passing area of the paper 9 having a small width, and the second frame 81 is not passing through the paper 9 having a small width. It is provided with a width TB in the roller axial direction X corresponding to the paper region. A space S1 is formed in a space surrounded by the first frame 74 and the heat insulating cover 78, and a space S2 is formed in a space surrounded by the second frame 81 and the heat insulating cover 78.

  A plurality of first hollow members 71 are provided in the gap portion S1, and a plurality of second hollow members 72 are provided in the pair of gap portions S2. A fusion bonding layer 62 (see FIG. 4) is formed on each outer peripheral surface of the first and second hollow members 71, 72, and, similar to the first embodiment, a plurality of first and second hollow members 71, 72 is assembled into the gaps S1 and S2, respectively.

  A movable frame 82 is provided on the outer side of the second frame 81 in the roller radial direction Y. The movable frame 82 constitutes the outer wall of the second frame 81 and is provided so as to be movable in the roller radial direction Y.

  The cam member 83 is an eccentric cam that is rotatably held by the apparatus main body, and is provided so as to always contact the movable frame 82. When the cam member 83 rotates 180 degrees from the state shown in FIG. 7, the movable frame 82 moves to the heat insulating cover 78 side, and the gap S2 is compressed as shown in FIG. When the gap S <b> 2 is compressed, the second hollow member 72 is crushed against elasticity, and the air layer is substantially eliminated in the hollow portion of the second hollow member 72. Further, when the cam member 83 is rotated 180 degrees from the state shown in FIG. 8, the second hollow member 72 is restored to a cylindrical shape by its elastic force, so that the movable frame 82 is pushed upward in FIG. It becomes. Instead of the cam member 83, the movable frame 82 may be moved in the roller radial direction Y by a member that pushes and pulls the movable frame 82 in the roller radial direction Y.

  According to the third embodiment, the plurality of second hollow members 72 provided in the second gap S <b> 2 can be elastically deformed, and the second gap S <b> 2 is the outer wall of the second frame 81. It can be compressed by a movable frame 82 configured to be movable in the roller radial direction at the portion.

  With this configuration, when the sheet 9 having the maximum width that can be passed is fixed, the cam member 83 is in the state shown in FIG. 7, so that each hollow portion of the plurality of second hollow members 72 is in the gap portion S <b> 2. In the roller radial direction Y and the roller circumferential direction, the flow of the air layer stays. Therefore, heat can be prevented from flowing out of the apparatus in the gap S2 together with the gap S1, and the heat insulation performance can be enhanced over the entire widths TA and TB.

  In addition, with this configuration, when the paper 9 having a small width is fixed, the movable frame 82 is moved toward the heat insulating cover 78 in the roller radial direction Y by the cam member 83, thereby pushing the plurality of second hollow members 72. Crush. Accordingly, the air layer is substantially eliminated in the hollow portion of the second hollow member 72, and the heat of the width TB corresponding to the non-sheet passing region is diffused, so that the width TB and the width TA corresponding to the sheet passing region are reduced. Temperature difference generated between the two can be eliminated.

(Fourth embodiment)
FIG. 9 is a plan view showing a hollow member according to the fourth embodiment. The fourth embodiment is different from the first to third embodiments in that a plurality of hollow members are bundled and assembled with a film.

  The film 86 is wound around the outer periphery of the plurality of hollow members 61 in a state where the plurality of hollow members 61 are in contact with the outer peripheral surfaces. The film 86 is made of a heat-resistant sheet material such as polyimide resin or polyamide resin. The hollow member 61 is made of the same material as in the first to third embodiments.

  After housing the plurality of hollow members 61 bundled with the film 86 in the upper frame 56 (see FIG. 2), the heat insulating cover 57 (see FIG. 2) is attached to the upper frame 56. By adopting such a manufacturing method, the plurality of hollow members are easily filled in the gaps.

  The film 86 may be configured as shown in FIG. FIG. 10 is a plan view showing a modification of the film. The film 86 is provided longer than the hollow member 61 in the roller axial direction X. After the film 86 is wound around the outer periphery of the plurality of hollow members 61, the film 86 is attached to the plurality of hollow members 61 such that both ends of the film 86 cover both end surfaces of the plurality of hollow members 61. By adopting such a manufacturing method, the plurality of hollow members 61 are easily filled in the gap portion S, and the hollow portion 61a (see FIG. 4) of the hollow member 61 is sealed. There is no possibility of air leaking out, and the heat insulating property of the gap S can be maintained.

  In the second and third embodiments, the hollow members 71 and 72 are provided in the gap S on the fixing roller 18 side. However, in the present invention, the hollow member is provided in the gap S on the pressure roller 19 side. Even in the configuration in which 71 and 72 are provided, the same effects as those of the above-described embodiment can be obtained.

  In the first to fourth embodiments, the fixing roller 18 is applied to a heater heating method in which the fixing roller 18 is heated by the heater 43. However, the present invention is not limited to this, and the fixing roller 18 is an induction heating layer. And may be applied to an electromagnetic induction heating method in which the fixing roller 18 is heated by electromagnetic induction. In this case as well, the same effects as in the above embodiment can be obtained.

  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 an electrophotographic method, an image forming apparatus including the same, and a method for manufacturing the fixing device. .

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Fixing apparatus 18 Fixing roller (one roller)
19 Pressure roller 43 Heater (heating means)
55 Lower frame 56 Upper frame (frame)
56a Side wall portion 56b Upper wall portion 57, 58 Thermal insulation cover 61 Hollow member 61a Hollow portion 62 Melting adhesive layer 71 First hollow member 72 Second hollow member 74 First frame body 75 Second frame body 76 Outside open / close member 77 Inner opening / closing member 78 Heat insulating cover 79 Blowing member 81 Second frame body 82 Movable frame 83 Cam member 86 Film N Nip portion S Cavity portion S1 First gap portion S2 Second gap portion X Roller axial direction Y Roller radial direction

Claims (10)

A toner image having a fixing roller heated by a heating unit and a pressure roller pressed against the fixing roller, and carried on a recording medium at a nip portion where the fixing roller and the pressure roller are pressed against each other In a fixing device for fixing a recording medium to a recording medium,
A heat insulating cover arranged at a predetermined interval from a part of the outer peripheral surface of at least one of the fixing roller or the pressure roller;
A frame that is arranged outside the heat insulating cover and constitutes an outer frame of the device and forms a gap between the heat insulating cover, and
A plurality of cylindrical hollow members filled in the gap so that the outer peripheral surfaces are in contact with each other in the radial direction of the at least one roller,
The fixing device according to claim 1, wherein the plurality of hollow members are filled such that both end portions abut against inner walls of the gap portion in the roller axial direction . The gap portion includes a first gap portion corresponding to a sheet passing region having a width smaller than the maximum width sheet passing region, and a second gap portion corresponding to a non-sheet passing region formed at both ends in the roller axis direction. And is divided into
The second gap portion includes a first opening and closing member that opens and closes one of both end sides in the roller axial direction.
The fixing device according to claim 1, wherein the first opening / closing member opens the second gap when a narrow recording medium is passed through the nip portion . A second opening / closing member capable of opening and closing the other of the both ends of the second gap, and a blowing member capable of blowing air from one of the second gaps to the other;
When the narrow recording medium is passed through the nip portion, the first and second opening / closing members open both ends of the second gap portion, and the air blowing member is one of the second gap portions. The fixing device according to claim 2, wherein air is sent from one to the other . The fixing device according to claim 1 , wherein the hollow member is formed of an elastic material . The gap portion includes a first gap portion corresponding to a sheet passing region having a width smaller than the maximum width sheet passing region, and a second gap portion corresponding to a non-sheet passing region formed at both ends in the roller axis direction. And is divided into
The plurality of hollow members provided in the second gap portion can be elastically deformed, and the second gap portion constitutes a part of the outer wall portion of the frame body and can reciprocate in the roller radial direction. Has a movable frame,
When the narrow-width recording medium is passed through the nip portion, the movable frame is disposed at the first position closest to the one roller, so that the second gap portion is compressed and the plurality of the plurality of gaps are compressed. When the hollow member is crushed and the recording medium having the maximum width is passed through the nip portion, the movable frame is disposed at the second position farthest from the one roller, whereby the second gap The fixing device according to claim 1 , wherein the fixing unit is expanded to restore the plurality of hollow members to an original state . The fixing device according to claim 1, wherein a surface of the heat insulating cover that faces at least one roller outer peripheral surface is a reflective surface . The fixing device according to claim 1, wherein the heat insulating cover and the frame body are disposed at a predetermined distance from at least an outer peripheral surface of the fixing roller . An image forming apparatus comprising the fixing device according to claim 1 . A heat insulating cover arranged at a predetermined interval from a part of the outer peripheral surface of at least one of the fixing roller or the pressure roller;
A frame that is arranged outside the heat insulating cover and constitutes an outer frame of the device and forms a gap between the heat insulating cover, and
A plurality of cylindrical hollow members filled in the gap so that outer peripheral surfaces thereof are in contact with each other in the radial direction of the at least one roller,
A melt adhesive layer is formed on the outer peripheral surface of the plurality of hollow members, and the plurality of hollow members formed with the melt adhesive layer are filled in the gap, and then left at a temperature equal to or higher than the melting point of the melt adhesive layer for a predetermined time. A method of manufacturing a fixing device . A heat insulating cover arranged at a predetermined interval from a part of the outer peripheral surface of at least one of the fixing roller or the pressure roller;
A frame that is arranged outside the heat insulating cover and constitutes an outer frame of the device and forms a gap between the heat insulating cover, and
A plurality of cylindrical hollow members filled in the gap so that outer peripheral surfaces thereof are in contact with each other in the radial direction of the at least one roller,
A method of manufacturing a fixing device , comprising: bundling with a film covering both end faces of the plurality of hollow members, and filling the plurality of bundled hollow members into the gap .