JP2012008325A - Fixing device and image forming apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device having a simple structure and capable of ensuring position accuracy (of bearings).SOLUTION: The fixing device comprises a heating roller 14, a pressure roller 15, driving side bearings 56, 57 and a driven side bearing 51 that support each end of the heating roller 14, a holding member 48 that holds the driven side bearing 51, and a frame 50 that holds the holding member 48. An ejection port 70 extending in a horizontal direction perpendicular to the axis direction of the heating roller 14 is formed in the frame 50, and a slide bearing part 71 is formed in the ejection port 70 so as to be capable of sliding the holding member 48.

Description

  The present invention relates to an image forming apparatus such as a laser beam printer, and more particularly to a heating roller replacement mechanism in the fixing apparatus.

  As a fixing device of an image forming apparatus such as a laser beam printer or a copying machine, a recording medium holding an unfixed toner image on the surface is sandwiched between a heating roller and a pressure roller, and heated and pressed while being conveyed. There is known a fixing device configured to fix a toner image onto the recording medium. The pressure roller is provided so as to be in pressure contact with the heating roller.

  Inside the heating roller, multiple heater lamps are installed as heat sources, and the heat capacity required for fixing the toner image is generally increased as the image forming apparatus with a high printing speed or the image forming apparatus that supports high reaming paper is used. Therefore, the heating roller must be maintained above a certain temperature, and the fixing temperature becomes higher.

  When the heating roller maintained at such a high temperature has reached the end of its life and the heating roller is to be replaced, after the operation of the image forming device has been stopped, the temperature of the heating roller itself has been cooled to such an extent that it can be replaced. When the maintenance engineer removes the heating roller from the fixing device and replaces it with a new heating roller, it takes time to cool the heating roller, which is very inefficient. This not only lengthens the downtime of the image forming apparatus, lowers the operating efficiency of the image forming apparatus, but also increases the cost of replacement maintenance work.

  In recent years, image forming apparatuses have been required to support high printing speeds, high image quality, and various types of paper. In fixing apparatuses, when high-speed printing is required, heat supply necessary for toner image fixing is required. Heat roller with a thin surface layer coated with PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) resin for the purpose of speeding up. When high image quality is required, crushing and blurring when fixing the toner image A heating roller whose surface layer is covered with silicon rubber or the like for the purpose of minimizing the temperature, and when a certain level of image quality and durability of the heating roller are required, a PFA is formed on the silicon rubber layer. Several types of heating rollers are required to be used, such as a heating roller covered with a tube.

  Therefore, in order to meet the demand for one image forming apparatus, it is necessary to change to a heating roller that meets the demand. However, although the heating roller has a slight difference depending on the type, it basically has a large heat capacity, and the roller is cooled from the high temperature, which is the maintenance temperature of the heating roller to supply the amount of heat necessary for optimal toner image fixing, and the roller is replaced. It took a considerable amount of time to become possible.

Regarding the replacement of the heating roller, for example, Patent Document 1 as described below can be cited.
7 and 8 are a partial cross-sectional view of the fixing device described in Patent Document 1 and a perspective view showing a state when the heating roller is replaced.

  As shown in FIG. 7, one end of the heating roller 100 is supported on the frame 102 via a support flange 101. The bearing flange 101 has a bearing 103, and the bearing 103 is fitted to the opening end of the heating roller 100 together with the centering member 104. Although not shown, the other end of the heating roller 100 is also supported by a support flange via a bearing.

  The support flange 101 is fixed to the frame 102 via a thumbscrew 106. A holding pawl 108 is fixed to the support flange 101 via a thumbscrew 107, and the holding pawl 108 has a function of fixing the heating roller 100 when the heating roller 100 is replaced.

  A plurality of radiator modules 105 are arranged inside the heating roller 100, and one end of the radiator module 105 is held at the center of the support flange 101 via a holding member 109. Although not shown, the other end of the radiator module 105 is also indirectly held by the support flange via a holding member.

  As shown in the figure, the connector 110 provided at the end of the radiator module 105 projects outward from the support flange 101 in a state where the radiator module 105 is held at the center of the support flange 101. A grip 111 for exchanging the heating roller 100 is integrally provided on the support flange 101, and this grip 111 is provided so as to straddle the connector 110 of the radiator module 105 protruding from the support flange 101. .

  When replacing the heating roller 100, the thumbscrew 106 is loosened, the grip 111 is held with one hand as shown in FIG. 8, and the heating roller 100 is pulled out of the frame 102 together with the support flange 101 and the like. At this time, in order to prevent the heating roller 100 from coming into contact with the frame 102 when passing through the opening of the frame 102, felt 130 is attached to the outer periphery of the opening of the frame 102 to prevent damage to the heating roller 100.

  The heating roller used in this type of fixing device has a cylindrical shape with a diameter of about 100 mm and a length of 500 mm or more, and itself has a considerable weight. Under such circumstances, in the fixing device disclosed in Patent Document 1, the heating roller 100 is supported by the support flange 101 while holding the grip 111 with one hand and supporting the heating roller 100 with the other hand wearing gloves 120. When pulling out from the frame 102 together with the above, the operation during the insertion / extraction operation is unstable due to the weight and heat of the heating roller 100 and the like. For this reason, there is a risk that the heating roller 100 may come into contact with other parts such as the frame 102 and damage the surface of the roller during the replacement operation of the heating roller 100.

  As described above, since the posture of the heating roller 100 is unstable and there is no auxiliary tool for stabilizing the posture of the heating roller 100, in the embodiment disclosed in Patent Document 1, the heating roller 100 is replaced with the heating roller 100 at the time of replacement. This is done with a hand wearing gloves 120. However, there is a problem in operability, such as a burn when touching the heating roller 100 in a high temperature state, and a mold release agent or lubricating oil adhering to the heating roller 100 adheres to the glove 120 and the like.

  Also, when holding the grip 111 with one hand and pulling out the heating roller 100 together with the support flange 101 and the like from the frame 102, there is a risk of touching the frame 102 and scratching the roller surface. A felt 130 is attached in the vicinity of the opening for protection. However, since the heating roller 100 to which the release agent or lubricating oil is attached is slid, dirt accumulates on the felt 130, which is insufficient for protecting the surface of the heating roller 100.

  Further, every time the heating roller 100 is replaced, an operation of attaching or peeling the felt 130 is necessary, which makes the replacement operation complicated. Further, since the felt 130 becomes dirty each time the heating roller 100 is replaced, it is necessary to dispose of the dirty felt 130 and to prepare a new felt 130.

  In addition, the fixing roller mechanism described in Patent Document 2 described later includes a frame member that holds both ends of the roller shaft, and both ends of the heat roller shaft, and is slidable on the frame member. A pair of mounted heat roller bearing members are held by lever members. Further, the frame member can take out a pair of heat roller bearing members in a direction perpendicular to the axis.

  However, in the fixing device roller mechanism described in Patent Document 2, since the lever member is fixed after the bearing portion is attached to the frame, the lever member is necessary, the number of parts increases, the structure becomes complicated, There is a disadvantage of incurring high costs.

  An object of the present invention is to solve such drawbacks of the prior art, to fix the fixing roller to the bearing of the fixing device with a simple structure, and to easily secure the fixing roller mounting position accuracy and the fixing device The present invention provides an image forming apparatus including the above.

In order to achieve the above object, the first means of the present invention comprises:
A heating roller;
A pressure roller provided in pressure contact with the heating roller;
A driving side bearing and a driven side bearing that rotatably support both ends of the heating roller;
A holding member for holding the driven bearing;
A frame for holding the holding member;
In the fixing device in which the heating roller and the holding member are detachable together with respect to the driving side bearing and the frame,
An extraction port extending in the horizontal direction perpendicular to the axial direction of the heating roller is formed in the frame portion that holds the holding member, and a slide bearing portion for sliding the holding member is provided in the extraction port. It is characterized by.

According to a second means of the present invention, in the first means,
The slide bearing portion is made of a heat-resistant resin material such as polytetrafluoroethylene.

According to a third means of the present invention, in the first means,
Forming a substantially circular opening in a portion of the frame that holds the holding member, and forming a takeout port extending in a horizontal direction perpendicular to the axial direction of the heating roller so as to communicate with the opening;
The holding member is provided with a frame fitting portion that fits into the opening of the frame portion, and a cylindrical portion on the inner side in the axial direction of the heating roller than the frame fitting portion,
When the outer diameter of the frame fitting portion is D1, the inner diameter of the opening is D2, the outer diameter of the cylindrical portion is D3, and the vertical distance of the slide bearing portion is H, the following dimensional relationship is satisfied. It is a feature.

D1 ≒ D2
D1, D2> D3
H> D3
According to a fourth means of the present invention, in the third means,
A surface layer is provided on a paper passing area on the peripheral surface of the heating roller,
An abutting portion that protrudes radially outward from the cylindrical portion is provided inside the cylindrical portion in the heating roller axial direction,
When the outer diameter of the abutting portion is D4, the following dimensional relationship is provided.

D4> D2
D4> H
A fifth means of the present invention is the first to fourth means,
A roller replacement tray can be removably mounted below the heating roller.

In order to achieve the above object, the sixth means of the present invention comprises:
A photoconductor, a charger for charging the surface of the photoconductor, an exposure device for forming an electrostatic latent image on the surface of the charged photoconductor, and developing the electrostatic latent image to form a toner image on the photoconductor An image forming apparatus comprising: a developing device that forms a toner image; a transfer device that transfers a toner image on the photoreceptor onto a recording medium; and a fixing device that fixes the transferred toner image on the recording medium.
The fixing device is a fixing device of the first to fifth means.

  The present invention is configured as described above, and has a simple structure. The fixing roller can be fixed to the bearing of the fixing device, and the fixing roller mounting position accuracy can be easily secured, and an image including the same. A forming apparatus can be provided.

FIG. 4 is a cross-sectional view showing a state in the middle of taking out the heating roller from the fixing device in the embodiment of the present invention. In the Example of this invention, it is sectional drawing which shows the state with which the heating roller and the holding member were integrated. FIG. 6 is a perspective view showing a state in which the heating roller is taken out from the fixing device in the embodiment of the present invention. In the Example of this invention, it is explanatory drawing which shows the state which slides the cylindrical part of a holding member on the slide bearing part provided in the flame | frame, and takes out a heating roller. FIG. 3 is a cross-sectional view showing a structure near a heating roller of a fixing device in an embodiment of the present invention. 1 is a schematic configuration diagram of a laser beam printer according to an embodiment of the present invention. It is a partial cross-sectional view of a conventionally proposed fixing device. It is a perspective view showing a state when the heating roller of the fixing device is replaced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Overall configuration of laser beam printer)
First, a laser beam printer using an electrophotographic system is exemplified as an image forming apparatus to which the present invention is applied, and the overall configuration will be described with reference to FIG.

  In the figure, reference numeral 1 denotes a laser beam printer. The photosensitive drum 21 starts to rotate in the direction of the arrow based on a printing operation start signal from the controller 22. The photosensitive drum 21 rotates at a speed corresponding to the printing speed of the laser beam printer 1 and continues to rotate until the printing operation is completed. When the photosensitive drum 21 starts to rotate, a high voltage is applied to the corona charger 2 and, for example, positive charges are uniformly charged on the surface of the photosensitive drum 21.

  The rotary polygon mirror 3 starts rotating as soon as the laser beam printer 1 is turned on, and maintains constant speed rotation with high accuracy while the power is turned on. Light output from the light source 4 such as a semiconductor laser is reflected by the rotary polygon mirror 3 and irradiated while scanning the photosensitive drum 21 through the fθ lens 5.

  When character data or graphic data converted into a dot image is sent from the controller 22 to the laser beam printer 1 as a laser beam on / off signal, the surface of the photosensitive drum 21 is irradiated with the laser beam and the non-irradiated portion. Are formed, and a so-called electrostatic latent image is formed. When the photosensitive drum area holding the electrostatic latent image reaches a position facing the developing device 6, toner is supplied to the electrostatic latent image, and the portion of the photosensitive drum 21 on which the electric charge has disappeared due to the laser beam irradiation, For example, a positively charged toner is attracted by static electricity and a toner image is formed on the photosensitive drum 21.

  The continuous sheet 7 stored in the sheet hopper 11 is synchronized with the timing at which the toner image of the print data formed on the photosensitive drum 21 reaches the transfer position by the sheet conveying tractor 8 and the transfer unit. 10 is conveyed toward the middle.

  The toner image formed on the photosensitive drum 21 is sucked onto the sheet 7 by the action of the transfer unit 10 that applies a charge having a polarity opposite to that of the toner image to the back side of the sheet 7.

  In this way, the paper 7 set in the paper hopper 11 is transported to the fixing device 12 through the paper transport tractor 8, the transfer device 10, the paper transport tractor 9, and the buffer plate 24. The paper 7 that has reached the fixing device 12 is preheated by a preheater 13 having a plurality of heaters therein, and then a pair of fixing rollers including a heating roller 14 having a plurality of lamps 25 and a pressure roller 15 therein. The toner image is melted and fixed on the sheet 7 while being nipped and conveyed while being heated and pressurized by the formed nip portion. In a high-speed printing apparatus, it is common to replace the heating roller 14 as a single unit, and it is not a good idea because it is expensive to replace the gears integrally as in a small-sized printing apparatus.

  The paper 7 sent out by the heating roller 14 and the pressure roller 15 is sent out to the stacker table 19 by the paper feed roller 16 and is alternately folded along the perforation by the swinging motion of the swing fin 17. Further, while the folded state is adjusted by the rotating paddle 18, they are stacked on the stacker table 19. The area that has passed the transfer position of the photosensitive drum 21 is cleaned by the cleaning device 20 and is prepared for the next printing operation.

  In FIG. 6, reference numeral 23 denotes a display screen for displaying information based on the state of the laser beam printer 1 during the printing operation. Further, the buffer plate 24 described above absorbs slack or tension generated on the sheet 7 when a sheet conveyance speed difference occurs between the sheet conveyance tractor 9 and the fixing roller (the heating roller 14 and the pressure roller 15). Is for. Reference numeral 26 denotes a web member provided so as to be able to come into contact with the surface of the heating roller 14 and to be wound up. The web member 26 is used to apply oil as a release agent to the surface of the heating roller 14.

(Structure around the heating roller)
Next, the structure in the vicinity of the heating roller of the fixing device 12 will be described with reference to FIG. The heating roller 14 includes, for example, a metal base tube 14a such as aluminum, PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) resin, silicon provided on a paper passing region on the peripheral surface of the base tube 14a. The surface layer 14b is made of a PFA tube or the like coated on a rubber or silicon rubber layer.

  Inside the vicinity of the opening portions at both ends of the heating roller 14, heat radiation preventing members (hereinafter referred to as absorbers) 14c and 14d such as aluminum are fixed. The absorbers 14c and 14d prevent the radiant heat from the plurality of lamps 25 inserted inside the heating roller 14 from being released to the outside of the heating roller 14 and causing the inside of the machine to become high temperature.

  Both ends of the heating roller 14 are supported by the frame 50 of the fixing device via holding members 48 and 49 having centering members 46 and 47.

  The holding member 48 is provided with a centering member 46 via a driven-side bearing 51, and the centering member 46 is inserted inside the opening end of the heating roller 14. Also, the bearing 51 absorbs the thermal expansion of the heating roller 14 and variations in surrounding support members by a plurality of springs 52 installed in the circumferential direction of the bearing 51 and a stopper plate 53 attached to the inner end surface of the holding member 48. It can be done. In the state in which the heating roller 14 is incorporated, the spring 52 is slightly compressed, and a gap is formed between the centering member 46 and the bearing 51 and the stopper plate 53 as shown in FIG. The holding member 48 is fixed to the frame 50 by a plurality of wing screws 54.

  The holding member 49 is provided with a gear 55 that receives a driving force from a motor (not shown) that rotationally drives the heating roller 14, and the holding member 49 is rotated by housings 58 and 59 via drive side bearings 56 and 57. It is supported freely. In order to prevent the outflow and damage of heat from the heating roller 14 to the centering members 46, 47, a heat-resistant plastic ring 60 is interposed between both ends of the heating roller 14 and the centering members 46, 47.

  A plurality of lamps 25 serving as heat sources for the heating roller 14 are bundled by lamp holders 61 and 62 that hold both ends of each lamp 25 to form a lamp cartridge 63. The lamp cartridge 63 is heated as shown in the figure. It is installed at the inner center of the roller 14.

  When taking out the lamp cartridge 63 from the heating roller 14, the protection member 64 is inserted from the through hole 59a side of the housing 59 as shown by the arrow B in FIG. As a result, the lamp 25 can be prevented from being damaged during handling of the lamp cartridge. The paper tube is suitable as the protective member 64 because it has a heat insulating property, has a predetermined mechanical strength, is inexpensive and easily available.

(Heat roller take-out structure)
Next, the structure for taking out the heating roller 14 will be described with reference to FIGS. 1 is a cross-sectional view showing a state in the middle of taking out the heating roller 14 from the fixing device, FIG. 2 is a cross-sectional view showing a state in which the heating roller 14 and the holding member 48 are integrated, and FIG. 3 is a view showing taking out the heating roller 14 from the fixing device. FIG. 4 is an explanatory view showing a state in which the heating roller 14 is taken out by sliding the cylindrical portion 68 of the holding member 48 on the slide bearing portion 71 provided on the frame 50. In FIG. 3, the drawing of the holding member 48 is omitted because the drawing becomes complicated.

  A stepped frame fitting portion 66 is provided on the flange portion of the holding member 48, and an outer diameter D1 (see FIG. 2) of the frame fitting portion 66 is a substantially circular shape formed in the frame 50. The opening 67 is designed to have substantially the same dimension (D1≈D2) as the inner diameter D2 (see FIGS. 3 and 4).

  In this dimensional relationship, as shown in FIG. 5, the frame fitting portion 66 of the holding member 48 is fitted to the opening 67 of the frame 50, and one opening end 14 e of the heating roller 14 is connected to the centering member via the ring 60. By fitting into 47, the heating roller 14 is held at an appropriate position in the fixing device.

  Further, the width of the frame fitting portion 66 in the axial direction is from the same dimension to about 20% with respect to the width (thickness) of the frame 50, and the frame fitting portion 66 is connected to the opening 67 of the frame 50. The heating roller 14 can be accurately positioned by being fitted to. The fitting is possible even if the axial width of the frame fitting portion 66 is less than 20% with respect to the width (thickness) of the frame 50, but the fitting portion between the holding member 48 and the frame 50 can be used. There is a concern that the bonding area of the heating roller 14 is reduced and the positional stability of the heating roller 14 is lacking.

  Between the frame fitting portion 66 of the holding member 48 and the centering member 46, there is provided a cylindrical portion 68 to be inserted into the opening 67 of the frame 50 when the heating roller 14 is taken out. An abutting portion 69 that protrudes in a flange shape is integrally formed at the inner end portion, that is, the end portion on the centering member 46 side.

  When the outer diameter of the cylindrical portion 68 is D3 and the outer diameter of the abutting portion 69 is D4 (the outer diameter of the abutting portion 69 is D4)> (the outer diameter of the frame fitting portion 66 D1≈the opening of the frame 50 The inner diameter D2 of the portion 67> (the outer diameter of the cylindrical portion 68 is D3) (see FIG. 2).

  As shown in FIG. 5, when the heating roller 14 is installed in the fixing device, one opening end 14 e of the heating roller 14 is externally fitted to the centering member 47 via the ring 60. The heating roller 14 is taken out of the fixing device together with the holding member 48. When the heating roller 14 is taken out, the heating roller 14 and the centering member 47 are heated by a fitting width dimension X (see FIG. 1) or more. It is necessary to move the roller 14 (holding member 48) in the A direction, and when the dimension X is moved, the frame fitting portion 66 is completely removed from the opening 67 of the frame 50 (the fitting is completely released). The axial width of the cylindrical portion 68 is determined so that the cylindrical portion 68 is positioned in the opening 67 of the frame 50.

  When the heating roller 14 is moved in the direction A, the surface layer 14b formed on the outer peripheral surface of the heating roller 14 may come into contact with the opening 67 of the frame 50 and damage the surface layer 14b. As described above, an abutting portion 69 protruding to the outer periphery is integrally formed at the inner end portion of the cylindrical portion 68. The outer diameter D4 of the abutting portion 69 is slightly larger than the inner diameter D2 of the opening 67 of the frame 50 (D4)> (D2).

  As shown in FIGS. 3 and 4, the frame 50 is formed with a takeout port 70 extending in front of the horizontal direction perpendicular to the axial direction of the heating roller 14 so as to communicate with the opening 67. Rail-shaped slide bearing portions 71 made of a heat-resistant resin material such as polytetrafluoroethylene are laid on both upper and lower ends of 70. The vertical distance H of the slide bearing portion 71 is slightly larger than the outer diameter D3 of the cylindrical portion 68 (H> D3), so that the cylindrical portion 68 slides on the slide bearing portion 71. Further, the outer diameter D4 of the abutting portion 69 and the vertical distance H of the slide bearing portion 71 are in a relationship of D4> H.

  A wider width dimension (width dimension along the axial direction of the heating roller 14) of the slide bearing portion 71 stabilizes the posture of the heating roller 14 when the heating roller 14 is pulled out. However, the slide bearing portion 71 is set so as not to enter the region of the surface layer 14 b provided on the peripheral surface of the heating roller 14 when the heating roller 14 is taken out.

  Further, as shown in FIG. 3, a roller replacement tray having a bottom surface 72a and a side surface 72b and having an L-shaped side surface and designed to be the same size as or slightly longer than the axial length of the heating roller 14. 72 is removably attached to the fixing device. An operation handle 76 is attached to a side surface 72b of the roller exchange tray 72, and the roller exchange tray 72 is made of a rigid metal material.

 Further, in order to slidably attach the roller replacement tray 72 to the fixing device, a tray pedestal 73 is provided below the heating roller 14, and the tray pedestal 73 is a pedestal rail that is movable in a horizontal direction perpendicular to the axial direction of the heating roller 14. 74, and the roller replacement tray 72 is detachably disposed on the pedestal rail 74.

  Accordingly, the roller replacement tray 72 slides on the pedestal rail 74, and the bottom surface 72 a of the roller replacement tray 72 moves to the lower part of the heating roller 14 and receives the heating roller 14.

  Reference numeral 77 in FIG. 3 denotes a door that movably supports the web member 26 and is installed at a position facing the heating roller 14 of the frame 50 so as to be opened and closed.

(How to remove the heating roller)
Next, a method for removing the heating roller 14 will be described. First, the protection member 64 is inserted from the direction of arrow B shown in FIG. 5 to cover the lamp cartridge 63, the connector of the power supply cable (not shown) is removed, and the lamp cartridge 63 covered with the protection member 64 is removed from the fixing device. .

  Next, as shown in FIG. 3, the door 77 is opened, the roller replacement tray 72 and the pedestal rail 74 are attached to the tray base 73, and the roller replacement tray 72 is slid on the base rail 74 while lowering the heating roller 14. Push in.

  Subsequently, the thumbscrew 54 (see FIG. 5) fixing the holding member 48 to the frame 50 is removed, and the end of the heating roller 14 is passed through a through hole (not shown) formed in the holding member 48. The heating roller 14 and the holding member 48 are connected to each other by screwing into a screw hole (not shown).

  The connection force at this time may be a connection force that can move the heating roller 14 by pulling a handle 75 (see FIG. 1) provided in the holding member 48 in the A direction. The handle 75 is detachably attached to the holding member 48.

  Using this handle 75, the heating roller 14 is moved by a dimension X in the A direction to remove the heating roller 14 from the centering member 47 as shown in FIG. 1, and the frame fitting portion 66 of the holding member 48 is moved to the frame 50. The cylindrical portion 68 of the holding member 48 is inserted into the opening 67 of the frame 50. At the end of this movement, the abutting portion 69 comes into contact with the inner surface of the frame 50 and further movement of the heating roller 14 is prevented.

  A state in which this movement is prevented is shown in FIG. 1, and the surface layer 14 b formed on the peripheral surface of the heating roller 14 is sufficiently separated from the opening 67 of the frame 50. Safety measures are taken so that the surface layer 14b does not come into contact with the opening 67 and become damaged.

  Next, the heating roller 14 and the holding member 48 are moved together in the horizontal direction perpendicular to the axial direction, the heating roller 14 is placed on the roller replacement tray 72, and moved to a position where it contacts the side surface 72b of the roller replacement tray 72. At this time, as shown in FIG. 4, the cylindrical portion 68 of the holding member 48 moves while sliding on the slide bearing portion 71 and the abutting portion 69 is in sliding contact with the inner surface of the slide bearing portion 71. The movement in the axial direction is maintained.

  Thereafter, the roller replacement tray 72 is pulled out to the front side, and the heating roller 14 and the holding member 48 are removed from the fixing device while being placed on the roller replacement tray 72. After removal, the thumbscrew 54 is loosened and the heating roller 14 is separated from the holding member 48.

  When the heating roller 14 is newly mounted on the fixing device, the heating roller 14 is smoothly mounted at an appropriate position by performing the reverse operation of taking out the heating roller 14 described above.

  In the fixing device according to the present embodiment, the surface layer 14b of the heating roller 14 does not pass through the opening 67 and the takeout port 70 of the frame 50, so that the surface layer 14b is protected at the opening 67 and the takeout port 70 of the frame 50. There is no need to install a flaw prevention member such as a felt.

  DESCRIPTION OF SYMBOLS 1 ... Laser beam printer, 2 ... Corona charger, 3 ... Rotary polygon mirror, 4 ... Light source, 6 ... Developing apparatus, 7 ... Paper, 10 ... Transfer device, DESCRIPTION OF SYMBOLS 12 ... Fixing device, 13 ... Preheater, 14 ... Heating roller, 14a ... Element tube, 14b ... Surface layer, 14c ... Heat radiation prevention member (absorber), 14d ... Heat radiation Preventing member (absorber), 15 ... pressure roller, 21 ... photosensitive drum, 25 ... lamp, 46 ... centering member, 47 ... centering member, 48 ... holding member, 49 ... Holding member, 50 ... Frame, 51 ... Driven side bearing, 54 ... Thumbscrew, 56 ... Drive side bearing, 57 ... Drive side bearing, 63 ... Lamp cartridge, 66 ... Frame fitting part, 67 ... Opening part, 68 ... Cylindrical part 69 ... Abutting part, 70 ... Removal port, 71 ... Slide bearing part, 72 ... Roller exchange tray, 72a ... Bottom surface of roller exchange tray, 72b ... Roller exchange tray Side, 73 ... Tray base, 74 ... Base rail, 76 ... Operation handle, D1 ... Outer diameter of frame fitting part, D2 ... Inner diameter of opening, D3 ... Cylinder , D4..., X..., X... Axial fitting width dimension between heating roller and centering member, H.

Japanese National Patent Publication No. 5-504633 JP-A-5-333738

Claims (6)

A heating roller;
A pressure roller provided in pressure contact with the heating roller;
A driving side bearing and a driven side bearing that rotatably support both ends of the heating roller;
A holding member for holding the driven bearing;
A frame for holding the holding member;
In the fixing device in which the heating roller and the holding member are detachable together with respect to the driving side bearing and the frame,
An extraction port extending in the horizontal direction perpendicular to the axial direction of the heating roller is formed in the frame portion that holds the holding member, and a slide bearing portion for sliding the holding member is provided in the extraction port. A fixing device characterized by the above. The fixing device according to claim 1,
A fixing device in which the slide bearing portion is made of a heat-resistant resin material. The fixing device according to claim 1,
Forming a substantially circular opening in a portion of the frame that holds the holding member, and forming a takeout port extending in a horizontal direction perpendicular to the axial direction of the heating roller so as to communicate with the opening;
The holding member is provided with a frame fitting portion that fits into the opening of the frame portion, and a cylindrical portion on the inner side in the axial direction of the heating roller than the frame fitting portion,
When the outer diameter of the frame fitting portion is D1, the inner diameter of the opening is D2, the outer diameter of the cylindrical portion is D3, and the vertical distance of the slide bearing portion is H, the following dimensional relationship is satisfied. A fixing device characterized.
D1 ≒ D2
D1, D2> D3
H> D3 The fixing device according to claim 3.
A surface layer is provided on a paper passing area on the peripheral surface of the heating roller,
An abutting portion that protrudes radially outward from the cylindrical portion is provided inside the cylindrical portion in the heating roller axial direction,
A fixing device having the following dimensional relationship when the outer diameter of the abutting portion is D4.
D4> D2
D4> H The fixing device according to any one of claims 1 to 4,
A fixing device, wherein a roller replacement tray can be removably mounted below the heating roller. A photoconductor, a charger for charging the surface of the photoconductor, an exposure device for forming an electrostatic latent image on the surface of the charged photoconductor, and developing the electrostatic latent image to form a toner image on the photoconductor An image forming apparatus comprising: a developing device that forms a toner image; a transfer device that transfers a toner image on the photoreceptor onto a recording medium; and a fixing device that fixes the transferred toner image on the recording medium.
An image forming apparatus, wherein the fixing device is the fixing device according to claim 1.

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