Image heating apparatus and image forming apparatus

Abstract

The invention relates to an image heating apparatus and an image forming apparatus. The image heating apparatus includes a first rotating member, a second rotating member, a frame member, a guide portion, and a cover. The first rotating member is configured to heat a toner image formed on a recording material. The second rotating member is configured to be in contact with the first rotating member, and forms a fixing nip together with the first rotating member. The frame member is configured to support the first rotating member and the second rotating member. The guide portion is configured to guide the first rotating member to move upstream in a transport direction of the recording material when the first rotating member is being removed. The cover is attached to the frame member and is configured to rotate about a rotation axis to open and close the guide portion. The cover is configured to rotate in a direction toward the conveying direction to open the guide portion.

Description

[0001] This application is a divisional application of invention patent application 202110503207.0, filed on May 10, 2021, and entitled “Image heating device and imaging device”. Technical Field

[0002] The present invention relates to an image heating device for fixing a toner image transferred onto a recording material in an image forming apparatus using an electrophotographic system or an electrostatic recording system, and the image forming apparatus. Background Art

[0003] Hitherto, in an image forming apparatus adopting an electrophotographic system, an electrostatic latent image formed on a photosensitive drum serving as an image bearing member is developed using a toner to form a toner image, and the toner image is transferred onto a recording material before being fixed onto the recording material in a fixing unit (which is an example of an image heating device). An example of a widely used fixing unit is a heat-pressing type unit including a heating rotating member and a pressing rotating member that applies pressure to the heating rotating member, wherein a fixing nip portion formed between the heating rotating member and the pressing rotating member clamps and conveys the recording material, thereby fixing the toner carried on the recording material onto the recording material by heat and pressure.

[0004] The processing speed of an electrophotographic image forming apparatus is increasing, and in response thereto, the size of a heating rotating member in a fixing unit is increasing. Therefore, a fixing unit has been developed in which a heating rotating member stretched on a fixing roller and a heating roller is formed of a thin belt member (refer to Japanese Patent Application Publication No. 2011-123181). According to the fixing unit disclosed in Japanese Patent Application Publication No. 2011-123181, for example, a heating unit including a heating rotating member can be replaced relative to a frame member (e.g., a housing of the fixing unit) to facilitate maintenance and extend the service life of the heating rotating member forming a fixing nip portion.

[0005] However, according to the fixing unit disclosed in the above-mentioned Japanese Patent Application Publication No. 2011-123181, the cover of the frame member provided in the fixing unit is designed to be opened in the direction in which the heating unit is removed. Therefore, when the heating unit is removed from the frame member for replacement, the opened cover may block the heating unit and hinder the replacement operation of the heating unit.

[0006] The present invention provides an image heating apparatus and an image forming apparatus capable of improving the operability of attaching and detaching a heating unit to and from a frame member. Summary of the invention

[0007] According to a first aspect of the present invention, an image heating device includes: a first rotating member configured to heat a toner image formed on a recording material; a second rotating member configured to contact the first rotating member and form a fixing nip portion together with the first rotating member for conveying the recording material; a frame member configured to support the first rotating member and the second rotating member; a guide portion configured to guide the first rotating member to move upstream in a conveying direction of the recording material when the first rotating member is being removed; and a cover attached to the frame member and configured to rotate around a rotation axis to open and close the guide portion. The cover is configured to rotate in a direction toward the conveying direction to open the guide portion.

[0008] According to a second aspect of the present invention, an image forming apparatus configured to form an image on a recording material includes an image heating device, and a drawer portion configured to support the image heating device and to be withdrawn from the image forming apparatus.

[0009] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a cross-sectional view showing the overall configuration of an imaging device according to an embodiment.

[0011] Figure 2 is a control block diagram of the imaging device according to this embodiment.

[0012] Figure 3 is a cross-sectional view showing a state in which the heating unit is positioned at the attachment position and the cover is closed to form a fixing nip portion in the fixing unit according to the embodiment.

[0013] Figure 4 is a cross-sectional view showing a state in which the heating unit is positioned at the attachment position and the cover is opened in the fixing unit according to the embodiment.

[0014] Figure 5 is a cross-sectional view showing a state in which the heating unit is positioned at the insertion start position and the cover is opened in the fixing unit according to the embodiment.

[0015] Figure 6 is a cross-sectional view showing a state in which the heating unit is positioned outside the opening portion and the cover is opened in the fixing unit according to the embodiment.

[0016] Figure 7 is a cross-sectional view showing a state in which the heating unit is positioned at the attachment position and the cover is not closed in the fixing unit according to the embodiment.

[0017] Figure 8is a cross-sectional view showing a state in which, in the fixing unit according to the embodiment, the heating unit is positioned at the attachment position and the cover is closed and the fixing nip portion is not formed.

[0018] Fig. 9 is a perspective view showing a state in which the fixing unit is drawn out from the image forming apparatus in the fixing unit according to the embodiment. DETAILED DESCRIPTION

[0019] Will refer to Figures 1 to 9 One embodiment of the present invention is described in detail. In this embodiment, as an example of the imaging device 1, a cascade type full-color printer is shown. However, the present technology is not limited to being applied to the cascade type imaging device 1, and it can be applied to other types of imaging devices. In addition, the printer is not limited to a full-color printer, and it can be a black and white or monochrome printer.

[0020] Imaging device

[0021] like Figure 1 As shown, the image forming apparatus 1 is a full-color printer adopting an electrophotographic system, in which four image forming units PY, PM, PC, and PK of yellow, magenta, cyan, and black are provided in the main body of the apparatus. The present embodiment adopts a tandem intermediate transfer system, in which the image forming units PY, PM, PC, and PK are arranged along the rotation direction of the intermediate transfer belt 7 described later. The image forming apparatus 1 forms a toner image on a recording material S according to an image signal from a document reader (not shown) connected to the main body of the apparatus or a host device (e.g., a personal computer) connected to the main body of the apparatus and communicating therewith. Sheet materials such as paper, plastic film, and cloth are examples of the recording material S. In addition, the image forming apparatus 1 includes a control unit 20 for performing various controls (e.g., an image forming process).

[0022] The image forming process will be described. First, the image forming units PY, PM, PC, and PK will be described. In the present embodiment, the image forming units PY, PM, PC, and PK adopt substantially the same configuration except that the toner colors (which are yellow, magenta, cyan, and black) are different. The image forming unit PY of the yellow toner will be described below as an example, and the description of the other image forming units PM, PC, and PK will be omitted.

[0023] The imaging unit PY is mainly composed of a photosensitive drum 2, a charging device 3, an exposure unit 4, and a developing device 5. The surface of the photosensitive drum 2, which is an example of an image bearing member driven to rotate, is uniformly charged in advance by the charging device 3, and thereafter, an electrostatic latent image is formed on the photosensitive drum by the exposure unit 4 driven based on an image information signal. That is, an electrostatic latent image is formed on the photosensitive drum 2. The electrostatic latent image formed on the photosensitive drum 2 is developed by the toner in the developing device 5 and is visualized as a toner image. The toner in the developer consumed by the image formation is replenished together with the carrier from the toner cartridge not shown.

[0024] Thereafter, by applying a predetermined pressing force and a primary transfer bias voltage by the primary transfer roller 6 arranged opposite to the photosensitive drum 2 with the intermediate transfer belt 7 interposed therebetween, the toner image formed on the photosensitive drum 2 is primarily transferred onto the intermediate transfer belt 7. The transfer residual toner slightly remaining on the photosensitive drum 2 after the primary transfer is removed by the cleaning device 8 to prepare the photosensitive drum 2 for the subsequent image forming process.

[0025] The intermediate transfer belt 7 is stretched on the tension roller 10, the secondary transfer inner roller 11 and the driving roller 12. The intermediate transfer belt 7 is driven by the driving roller 12 to move in the direction of the arrow R1 in the figure. The image forming processes of each color performed by the above-mentioned image forming units PY, PM, PC and PK are performed at the set timing, so that the colorant images are sequentially superimposed on the colorant images previously formed on the intermediate transfer belt 7 upstream in the moving direction by the primary transfer. As a result, a full-color toner image is finally formed on the intermediate transfer belt 7 and is transferred to the secondary transfer portion T2. ​​The secondary transfer portion T2 is a transfer nip portion formed between the secondary transfer outer roller 13 and the intermediate transfer belt 7 stretched on the secondary transfer inner roller 11. The transfer residual toner remaining after passing through the secondary transfer portion T2 is removed from the intermediate transfer belt 7 by the transfer cleaning device 14.

[0026] The conveying process of the recording material S to the secondary transfer portion T2 is performed at a timing similar to the formation process of the toner image that has been conveyed to the secondary transfer portion T2. ​​During the conveying process, the recording material S is fed from a sheet cassette, etc., not shown, and is sent to the secondary transfer portion T2 at a timing that matches the formation of the image. At the secondary transfer portion T2, a secondary transfer voltage is applied to the secondary transfer inner roller 11.

[0027] As described, through the image forming process and the conveying process, the toner image is secondarily transferred from the intermediate conveying belt 7 to the recording material S at the secondary transfer portion T2. ​​Thereafter, the recording material S is conveyed to the fixing unit 30, and is subjected to heat and pressure by the fixing unit 30, whereby the toner image is melted and fixed to the recording material S. The fixing unit 30 is an example of an image heating device for fixing the unfixed toner image formed by the image forming unit to the recording material S.

[0028] Control unit

[0029] The imaging device 1 includes a control unit 20 for performing various controls such as the above-mentioned imaging operation. The operations of the respective units of the imaging device 1 are controlled by the control unit 20 provided in the imaging device 1. A series of imaging operations are controlled by the control unit 20 according to various input signals input through an operation portion provided on the upper side of the device body or via a network.

[0030] like Figure 2 As shown, the control unit 20 includes a CPU (Central Processing Unit) 21 as an operation control unit, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, and the like. The CPU 21 reads a program corresponding to a control process stored in the ROM 22 to perform control on each unit of the image forming apparatus 1. The RAM 23 stores working data and input data, and the CPU 21 performs control based on, for example, the aforementioned program with reference to the data stored in the RAM 23. A driving motor M1 for driving a fixing belt 41 and a pressure roller 32 (mentioned later) of the fixing unit 30, and a heater 48 and a thermistor 49 mentioned later are connected to the control unit 20.

[0031] Fusing unit

[0032] Next, we will refer to Figure 3 The fixing unit 30 will be described in detail. Figure 3 As shown, the fixing unit 30 is a belt heating type heating device in the form of a cartridge (refer to Figure 1 ). The fixing unit 30 includes a housing 31 as an example of a frame member, a heating unit 40, a pressure roller 32 as a second rotating member, a separation unit 50, and a cover 60. The housing 31 according to the present embodiment is formed by welding a plurality of metal plates together. However, the metal plates may be fixed by a method other than welding (e.g., by screwing).

[0033] Meanwhile, according to the present embodiment, the fixing unit 30 is composed of a drawer portion 100 (eg, Fig. 9 The fixing unit 30 can be accessed in a state where the cover 101 of the imaging device 1 is opened and the drawer portion 100 is pulled out in the pulling-out direction Y. In the present embodiment, the pulling-out direction Y is a horizontal direction orthogonal to the conveying direction X of the recording material, that is, the sheet conveying direction.

[0034] The heating unit 40 includes a fixing belt 41 (which is a rotatable endless belt) as a first rotating member, a pressure pad 42 as a fixing member, a heating roller 43, a steering roller 44, a bracket 45, and a unit side plate 46 integrating these members into a box. The heating unit 40 is detachably attached to the housing 31.

[0035] The fixing belt 41 is a thin, cylindrical belt member having thermal conductivity and heat resistance, and can abut and heat the recording material S. In the present embodiment, the fixing belt 41 adopts a three-layer structure including a base layer, an elastic layer formed on the periphery of the base layer, and a release layer formed on the periphery of the elastic layer. The base layer is formed of polyimide resin (PI) with a thickness of 30 μm, and the elastic layer is formed of silicone rubber with a thickness of 300 μm. The release layer is formed of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin with a thickness of 30 μm. The fixing belt 41 is stretched on the pressure pad 42, the heating roller 43, and the steering roller 44. The outer diameter of the fixing belt 41 is, for example, 120 mm.

[0036] The pressure pad 42 is supported by a bracket 45, and is pressed by the pressure roller 32 with the fixing belt 41 interposed therebetween. The bracket 45 is formed of stainless steel, and both ends of the bracket 45 in the rotation axis direction are supported by the fixing frame 33 of the housing 31 of the fixing unit 30. The bracket 45 includes a separation plate positioning portion 45a. The fixing nip portion N is formed by a contact portion of the fixing belt 41 and the pressure roller 32. The rotation axis direction refers to a direction orthogonal to the sheet conveying direction X of the recording material S that has passed through the fixing nip portion N.

[0037] The pressure pad 42 is formed of, for example, an LCP (liquid crystal polymer) resin. A lubricating sheet 47 is interposed between the pressure pad 42 and the fixing belt 41. A PI (polyimide) sheet having a thickness of 100 μm and coated with PTFE (polytetrafluoroethylene) is used as the lubricating sheet 47. The PI sheet has protrusions of 100 μm formed at intervals of 1 mm to reduce the contact area with the fixing belt 41, thereby reducing sliding resistance. A lubricant is applied to the inner side of the fixing belt 41 so that the fixing belt 41 slides smoothly on the pressure pad 42. The lubricant may be, for example, silicone oil.

[0038] The heating roller 43 is a stainless steel tube having a thickness of 1 mm and having a heater 48 formed of a halogen heater arranged inside the heating roller 43 (see Figure 2 ) to heat the heating roller to a predetermined temperature. The fixing belt 41 is heated by the heating roller 43 and based on the thermistor 49 (see Figure 2) The detected temperature is controlled to a predetermined target temperature according to the sheet type. In addition, the heating roller 43 has a gear (not shown) fixed to its first end portion in the rotation axis direction, and the heating roller 43 is connected to a drive motor M1 (see Figure 2 The fixing belt 41 is driven to rotate following the rotation of the heating roller 43 .

[0039] The steering roller 44 has a pivot axis arranged substantially in the vertical direction at a first end portion or near a center portion in the rotation axis direction, and pivots relative to the fixing belt 41 to generate a tension difference in the main scanning direction and adjust the position of the fixing belt 41 in the main scanning direction. In addition, the steering roller 44 is urged by a spring (not shown) supported by a frame of the heating unit 40, and functions as a tension roller for applying a predetermined tension to the fixing belt 41.

[0040] The pressure roller 32 is opposite to the fixing belt 41 and abuts against the fixing belt 41, thereby forming a fixing nip portion N in which pressure is applied between the pressure roller 32 and the fixing belt 41. The pressure roller 32 is a roller in which an elastic layer is formed on the outer periphery of the shaft and a release layer is formed on the outer periphery of the elastic layer. In the pressure roller 32, the shaft is formed of stainless steel, and the elastic layer is formed of conductive silicone rubber with a thickness of 3 mm. The release layer is formed of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin, and its thickness is 30 μm. The pressure roller 32 is axially supported on the housing 31 of the fixing unit 30 by a fixing frame 33, and a gear is fixed to the first end portion of the pressure roller 32 in the direction of the rotation axis, wherein the pressure roller is connected to the drive motor M1 (see Figure 2 ) and rotate.

[0041] The recording material S carrying the toner image (see Figure 1 ) is nipped by the fixing nip portion N formed between the fixing belt 41 and the pressure roller 32, and the toner image is heated while the recording material is conveyed. As described, the fixing unit 30 nipped and conveyed the recording material S while fixing the toner image onto the recording material S. Therefore, the fixing unit 30 must simultaneously realize the function of applying heat and pressure and the function of conveying the recording material S.

[0042] The separation unit 50 is provided on the fixing frame 33, and includes a separation plate 51, and a guide shaft 52 and a rotating shaft 53 protruding toward either side in the direction of the rotation axis. The separation unit 50 is axially supported on the fixing frame 33 in a swingable manner by the rotating shaft 53. The separation plate 51 is provided to separate the recording material S having passed through the fixing nip portion N from the fixing belt 41, and is formed by adhering a fluorine-based tape on a metal plate, and is used to prevent adhesion of toner and damage of an image on the recording material S due to sliding movement. The guide shaft 52 is arranged upstream of the rotating shaft 53 in the sheet conveying direction (direction D1 in the figure) X.

[0043] The fixing frames 33 are arranged on both side portions of the housing 31 in a fixed manner with respect to the rotation axis direction, and each fixing frame 33 is provided with a guide portion 34, a pressing frame 35, and a pressurizing spring 36. The bracket 45 of the heating unit 40 is inserted into the guide portion 34, pressed on the guide portion 34 by a pressing portion 80 described later, and fixed to the guide portion 34. After the bracket 45 is fixed to the guide portion 34, the pressing frame 35 is moved toward the heating unit 40 by a driving source and a cam (not shown), whereby the pressure roller 32 is pressed against the pressure pad 42 via the fixing belt 41. The pressing force of the pressure roller 32 to the pressure pad 42 during the image forming operation is set to 1000N, for example.

[0044] The guide portion 34 includes a support surface 34a, a positioning surface 34b as an example of a positioning portion, a slide surface 34c, and an opening portion 34d. The support surface 34a is formed on the opposite side of the pressure roller 32 along the attachment direction D1 for inserting the heating unit 40, and is positioned when the heating unit 40 is positioned. Figure 3 In the state at the attachment position shown, the fixing belt 41 supports the reaction force received from the pressure roller 32 at the inner peripheral side of the fixing belt 41. The positioning surface 34b is formed approximately vertically at the deepest part of the guide portion 34 in the attachment direction D1, and in the state where the heating unit 40 is positioned at the attachment position, the heating unit 40 is positioned by abutting the positioning surface 34b in the attachment direction D1. The sliding surface 34c is opposite to the supporting surface 34a and is formed along the attachment direction D1 so as to guide the bracket 45 by sliding movement when inserting or removing the heating unit 40. The opening portion 34d is an opening that connects the inside and the outside of the guide portion 34. By inserting the bracket 45 into the guide portion 34 through the opening portion 34d, the heating unit 40 can be moved to the attachment position, and by moving the bracket 45 out to the outside of the guide portion 34 through the opening portion 34d, the heating unit 40 can be removed from the housing 31. The guide portion 34 has a first guide portion 34 e extending in the horizontal direction, and a second guide portion 34 f connected to the first guide portion 34 e and extending obliquely upward in the direction opposite to the sheet conveying direction X.

[0045] When attaching the heating unit 40 to the housing 31, the guide portion 34 guides and causes the heating unit 40 to be inserted from the insertion start position (see Figure 5 ) to the attachment location (see Figure 3 ), so that the fixing belt 41 is positioned at the fixing nip portion N. The attachment position is a position where the bracket 45 abuts on the positioning surface 34b and the fixing belt 41 is positioned at the fixing nip portion N. In the present embodiment, the insertion start position is a position where the end of the bracket 45 in the attachment direction D1 is inserted between the support surface 34a and the slide surface 34c, at which the guidance by the guide portion 34 during insertion starts and the guidance by the guide portion 34 during removal ends, as shown in Figure 5 In addition, the area (defined by Figure 5 The region 402 (shown by the imaginary line in FIG. 1 ) is referred to as the movable region Ar1.

[0046] In the present embodiment, the attachment direction D1 for inserting the heating unit 40 is a direction along the sheet conveying direction of the recording material S nipped by the fixing nip portion N, which is set to be parallel in the illustrated example. However, the attachment direction D1 is not limited to being completely parallel to the sheet conveying direction X at the fixing nip portion N, and it may be approximately parallel, or the attachment direction D1 and the sheet conveying direction X may be set to opposite directions.

[0047] Further, the heating unit 40 is positioned as Figure 3 In the state of the attachment position shown, the position of the separation unit 50 relative to the fixing belt 41 is determined by the engagement of the guide shaft 52 of the separation unit 50 with the separation plate positioning portion 45a of the bracket 45. That is, the separation unit 50 held around the rotation shaft 53 in a swingable manner is engaged by the guide shaft 52 pressed on the engagement portion of the separation plate positioning portion 45a, thereby determining the position of the separation unit 50 in the swinging direction, and enabling the positioning of the separation unit 50 and the fixing nip portion N to be achieved.

[0048] The unit side plates 46 are arranged on both sides in the direction of the rotation axis. Each unit side plate 46 includes a first abutment surface 46a and a second abutment surface 46b. The second abutment surface 46b is arranged along the attachment direction D1 and is arranged continuously with the first abutment surface 46a, but the angle value is different. The details of the first abutment surface 46a and the second abutment surface 46b will be described later.

[0049] build

[0050] Next, the cover 60 will be described in detail. The cover 60 is provided to cover the opening portion of the housing 31 and the heating unit 40 attached to the housing 31, thereby protecting the heating unit 40 and shielding heat from the heating unit 40. The cover 60 includes a cover body 61, a cleaning unit 70, and a pressing portion 80.

[0051] The cover body 61 may cover the upper portion of the housing 31, both end portions of the housing 31 in the direction of the rotation axis, and both upstream and downstream side portions of the housing 31 in the attachment direction D1. Both end portions of the cover body 61 in the direction of the rotation axis are pivotally supported axially on the fixing frame 33 by a swing shaft 62 as an example of a rotation shaft. In the present embodiment, the swing shaft 62 is arranged downstream in the attachment direction D1 of the heating unit 40 positioned at the attachment position. That is, the cover body 61 is provided in a swingable manner, wherein the swing center with respect to the housing 31 is arranged downstream in the attachment direction D1 of the heating unit 40 located at the attachment position or the fixing nip portion N. The swing shaft 62 is not limited to being arranged downstream in the attachment direction D1 of the heating unit 40 located at the attachment position, and for example, even if the swing shaft 62 is not arranged downstream in the attachment direction D1 of the heating unit 40, the cover body 60 should be openable only in the attachment direction D1.

[0052] The cover body 61 includes an open / close engaging shaft 63 provided on both sides in the rotation axis direction on the outer diameter side of the swing shaft 62. When the cover 60 is closed, the open / close engaging shaft 63 engages with the fixing frame 33, thereby determining the position of the cover 60 relative to the fixing frame 33 in the swing direction.

[0053] The cover body 61 can be moved between the first position and the second position by a swinging motion. The first position is a position where the cover 60 covers the heating unit 40 positioned at the attachment position, such as Figure 3 That is, the state in which the cover body 61 is positioned at the first position is a closed state in which the guide portion 34 is closed. The second position is a state in which the cover body 60 has been moved from the movable area Ar1 (see Figure 5 ) is retracted and the heating unit 40 can be attached to or removed from the housing 31, such as Figure 4 In other words, the state in which the cover main body 61 is positioned at the second position is an open state in which the guide portion 34 is opened.

[0054] like Figure 3 As shown, the cover body 61 includes a shielding portion 64 which is positioned upstream in the attachment direction D1 of the heating unit 40 in the first position. In the present embodiment, in a state where the cover body 61 is positioned in the first position, the shielding portion 64 extends upstream in the attachment direction D1 of the heating unit 40 in the up-down direction and is positioned to be aligned with the movable area Ar1 (see Figure 5) overlap. Therefore, the heating unit 40 positioned at the attachment position cannot be removed, or the heating unit 40 cannot be attached from the outside. In addition, when the cover body 61 is positioned at the second position, as shown in FIG. Figure 4 As shown, the shielding portion 64 is moved to swing along with the swinging motion of the cover body 61, and the position of the shielding portion 64 is located downstream in the attachment direction D1 compared to its position in the state where the cover body 61 is located in the first position. Therefore, the heating unit 40 positioned in the attachment position can be easily removed, or the heating unit 40 can be easily attached from the outside without interference from the cover 60. When the cover body 61 is positioned in the second position, the cover body 61 will contact a stopper (not shown) provided on the housing 31 and cannot be further opened.

[0055] The cleaning unit 70 is an example of a contact portion, and is configured to clean the surface of the fixing belt 41. The cleaning unit 70 is arranged at a position such as Figure 3 In the first position shown in FIG. 1 , the fixing belt 41 of the heating unit 40 positioned at the attachment position is abutted, and in the position shown in FIG. Figure 4 The cleaning unit 70 includes an arm 71, a swing shaft 72, and a cleaning roller 73. The arm 71 is supported by the swing shaft 72 in a swingable manner relative to the cover 60. The cleaning roller 73 is configured to remove foreign matter attached to the surface of the fixing belt 41. In the present embodiment, the cleaning roller 73 is, for example, a brush roller having an outer diameter of approximately 10 mm, formed by winding a brush having a fiber bundle embedded therein on the surface of a core metal having a diameter of 6 mm formed of metal (e.g., stainless steel or electroplated iron). The pressing unit, not shown, moves the cleaning roller 73 axially supported on the arm 71 between a contact position and a separation position, and in the contact position, causes the cleaning roller 73 to contact the fixing belt 41 with a force of approximately 20 N. In the present embodiment, the cleaning roller 73 abuts against the fixing belt 41 during the imaging operation, and is separated from the fixing belt 41 during the non-imaging operation including the maintenance operation.

[0056] The pressing portion 80 is provided to press the bracket 45 of the heating unit 40 attached to the housing 31 against the positioning surface 34b and to position the heating unit 40 at the attachment position. The pressing portion 80 is a locking mechanism that stabilizes the position of the heating unit 40 relative to the fixing unit 30 by pressing the heating unit 40 against the fixing frame 33 in a state where the cover 60 is closed and positioned at the first position. The pressing portion 80 includes a pressing arm 81, a swing shaft 82, a pressing roller 83, a pressing spring 84, and a stopper 85.

[0057] The pressing arm 81 is axially supported by the swing shaft 82 on both side portions in the rotation axis direction of the cover body 61 in a swingable manner. The pressing roller 83 is axially supported by the pressing arm 81 in a rotatable manner. The pressing spring 84 is formed of, for example, a tension coil spring, and the pressing roller 83 pushes the pressing arm 81 in a direction to press the heating unit 40. Figure 4 As shown, in a state where the pressing roller 83 is not in contact with the heating unit 40 , the pressing arm 81 is in contact with the stopper 85 and the rotation of the pressing arm 81 is regulated.

[0058] Removal of the heating unit

[0059] Next, we will refer to Figures 4 to 6 The operation for removing the heating unit 40 from the fixing unit 30 according to the present embodiment is described. Generally, the maintenance operation is performed when the image forming process is not performed. Therefore, the removal of the heating unit 40 is performed when the pressure roller 32 and the cleaning roller 73 are removed from the fixing unit 30. Figure 3 The state shown is carried out in a state where the fixing belt 41 is separated. Figure 4 As shown, the cover 60 is moved to the second position in a state where the regulation by the opening / closing engagement shaft 63 is canceled and the cover 60 is swung in the swing direction R2 around the swing shaft 62. As a result, the pressing portion 80 pressing the heating unit 40 moves upward in the attachment direction D1, and the pressure applied to the heating unit 40 is canceled. As a result, the heating unit 40 can be removed in the removal direction D2 opposite to the attachment direction D1.

[0060] When the heating unit 40 is removed from the guide portion 34, as shown in FIG. Figure 5 As shown, the removal direction D2 is regulated by the sliding surface 34c. In a state where the heating unit 40 is moved in the removal direction D2, the engagement between the separation plate positioning portion 45a and the guide shaft 52 is released. The heating unit 40 moves in the removal direction D2 until the bracket 45 leaves through the opening portion 34d of the guide portion 34 formed on the fixing frame 33.

[0061] When the bracket 45 is removed to the outside through the opening portion 34d, the heating unit 40 can be removed from the fixing unit 30. Figure 6 As shown. In a state where the heating unit 40 is removed from the fixing unit 30, the separation plate 51 and the pressure roller 32 remain in the fixing unit 30. The cover 60 is positioned at a second position in which the cover is retracted in a direction opposite to the removal direction D2 of removing the heating unit 40, and the entire body of the cover 60 is retracted from the working area Ar2 (the area shown between the long dashed line and the short dashed line) for attaching and detaching the heating unit 40. Therefore, in the removal operation and the attachment operation of the heating unit 40, the cover 60 does not interfere with the movement route of the heating unit 40, nor does it hinder the operation.

[0062] Therefore, the operator will not have to take an unreasonable posture to work with the cover 60 interposed therebetween, but can work in a natural posture, thereby preventing deterioration of the operating performance due to the presence of the cover 60 or the occurrence of an excessive operation to remove the cover 60. In a state where the cover 60 is located at the second position, the cleaning roller 73 is separated from the fixing belt 41 and moves to the retracted position in the removal direction D2 of the heating unit 40. Therefore, during the removal operation and the attachment operation of the heating unit 40, the risk of the cleaning roller 73 contacting the fixing belt 41 and damaging the fixing belt 41 can be suppressed.

[0063] Heating unit attachment operation

[0064] Next, we will refer to Figure 6 , 5 , 4, 7, and 8 describe the operation for attaching the heating unit 40 to the fixing unit 30 according to the present embodiment in this order. Figure 6 As shown, when attaching the heating unit 40, the bracket 45 is inserted into the opening portion 34d of the guide portion 34 and the bracket 45 is placed on the sliding surface 34c, as shown in FIG. Figure 5 Then, the heating unit 40 is swung in the attachment direction D1, and the bracket 45 abuts against the positioning surface 34b, as shown in FIG. Figure 4 In this state, the guide shaft 52 of the separation unit 50 is engaged with the separation plate positioning portion 45a, and the relative positions of the heating unit 40 and the separation plate 51 are determined.

[0065] like Figure 7 As shown, in a state where the cover 60 is swung in the swing direction R3, the pressing arm 81 moves in a state of abutting against the stopper 85, and the pressing roller 83 abuts against the second abutting surface 46b formed on the heating unit 40. In a state where the cover 60 is further swung in the swing direction R3 with the pressing roller 83 abutting against the second abutting surface 46b, the pressing arm 81 swings in the swing direction R2 around the swing shaft 82 via the pressing roller 83, and separates from the stopper 85 against the pressing spring 84. Thus, the pressing force generated by the pressing spring 84 acts on the heating unit 40. That is, in a state where the heating unit 40 is positioned at the attachment position and the cover 60 moves from the second position to the first position, the pressing roller 83 abuts against the second abutting surface 46b before abutting against the first abutting surface 46a.

[0066] like Figure 8As shown, in a state where the cover 60 is closed and positioned at the first position, the pressing roller 83 presses the first abutting surface 46a of the heating unit 40 through the pressing spring 84. That is, in a state where the heating unit 40 is positioned at the attachment position and the cover 60 is positioned at the first position, the pressing roller 83 abuts against the first abutting surface 46a. In this state, the pressing force is decomposed according to the angle formed by the inclination angle of the first abutting surface 46a and the pressing direction of the pressing roller 83, and the pressing force is applied in the attachment direction D1 to press the heating unit 40 against the fixing frame 33. Thus, when the cover 60 is positioned at the first position, the pressing portion 80 abuts against the heating unit 40 positioned at the attachment position to press the heating unit 40 downstream along the attachment direction D1 and position the heating unit 40 on the positioning surface 34b.

[0067] The angle formed by the first abutting surface 46a and the attaching direction D1 should be close to 90 degrees to effectively press the heating unit 40 against the fixing frame 33. Therefore, the first abutting surface 46a preferably forms an angle of 45 degrees or more and 90 degrees or less with the attaching direction D1.

[0068] The second abutting surface 46b and the first abutting surface 46a have different inclination angles, but they are arranged continuously. Therefore, the pressing roller 83 can contact the second abutting surface 46b and apply a rotational force by the pressing spring 84 while moving toward the first abutting surface 46a, so that the pressing part 80 can press the heating unit 40 after contacting the heating unit 40. If the heating unit 40 is simply attached in place by the user, there may be a gap between the bracket 45 of the heating unit 40 and the positioning surface 34b of the guide part 34. On the contrary, by making the pressing roller 83 contact the first abutting surface 46a, a force that presses the bracket 45 on the positioning surface 34b can be generated, and the position and posture of the heating unit 40 can be preferably set.

[0069] As described, according to the fixing unit 30 of the present embodiment, in the state where the cover 60 is opened and positioned at the second position, the cover 60 is positioned downstream in the attachment direction D1 compared to when the cover 60 is closed and positioned at the first position. Therefore, by positioning the cover 60 at the second position retracted in the direction opposite to the removal direction D2 for removing the heating unit 40, the entire body of the cover 60 can be retracted from the working area Ar2 (refer to Figure 6 ), for attaching and detaching the heating unit 40. Therefore, during the operation of attaching and detaching the heating unit 40, the cover 60 does not overlap with the movement route of the heating unit 40, so that it is possible to suppress the hindrance of the operation and improve the operability. According to the present embodiment, the pivot angle from the first position where the cover body 61 is closed to the position where the cover body 61 abuts against a stopper (not shown) provided on the fixing unit 30 and opens is preferably 90 degrees or more and 135 degrees or less.

[0070] According to the fixing unit 30 of the present embodiment, the cover 60 includes the pressing portion 80. Therefore, when attaching the heating unit 40, the heating unit 40 can be pressed in the attaching direction simply by closing the cover 60, and the heating unit 40 can be accurately positioned and attached to the fixing unit 30.

[0071] Further according to the fixing unit 30 of the present embodiment, the cover 60 includes the cleaning unit 70. Therefore, when attaching and detaching the heating unit 40, the members and mechanisms contacting the surface of the fixing belt 41 can be retracted, and the attachment and detachment of the heating unit 40 can be facilitated.

[0072] According to the fixing unit 30 of the present embodiment, the second abutting surface 46b and the first abutting surface 46a are arranged continuously at different inclination angles. Therefore, the contact and pressing operation of the pressing roller 83 on the heating unit 40 can be performed continuously, and the heating unit 40 can be smoothly positioned at the attachment position.

[0073] The fixing unit 30 of the present embodiment described above has explained the case where both the heating roller 43 and the pressure roller 32 are driven by driving the drive motor M1, but the present technology is not limited to this. For example, the pressure roller 32 may be driven by the drive motor M1, and the fixing belt 41 may rotate following the rotation of the pressure roller 32. In this case, the heating unit 40 is pressed toward the sheet conveying direction X, so it is advantageous to attach the heating unit 40 along the sheet conveying direction X from the perspective of force. According to the fixing unit 30 of the present embodiment, the attachment direction D1 of the heating unit 40 is set to a direction parallel to the sheet conveying direction X of the recording material S clamped by the fixing clamping portion N, so it is also preferred in the above case.

[0074] Further, the fixing unit 30 of the present embodiment described above has exemplified the case where the cleaning unit 70 and the pressing portion 80 are provided on the cover 60, but the present technology is not limited thereto, and these components may be omitted. Further according to the fixing unit 30 of the present embodiment described above, the cover 60 is opened and closed by a swinging motion, but the present technology is not limited thereto. For example, the cover 60 may be opened and closed by a sliding motion.

[0075] Even further, the fixing unit 30 of the present embodiment described above has exemplified the use of a belt as the first rotating member, but the present technology is not limited thereto, and for example, the first rotating member may be a roller. In addition, the heating roller 43 may be omitted, and the heating source for the heating unit 40 may adopt a configuration that heats the first rotating member from the outside of the heating unit 40.

[0076] In addition, the fixing unit 30 of the above-mentioned embodiment adopts a structure in which the heating unit 40 is attached to and detached from the fixing unit 30 independently of the pressure roller 32, but the present technology is not limited to this, but a structure in which the heating unit 40 and the pressure roller 32 are integrally attached to and detached from the fixing unit 30 can be adopted.

[0077] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A fixing device configured to fix an unfixed toner image formed by an image forming unit onto a recording material, the fixing device comprising: a heating unit including a first rotating member configured to abut against and heat the recording material; a second rotating member configured to abut against the first rotating member and form a fixing nip portion that applies pressure between the second rotating member and the first rotating member; a housing configured to support the second rotating member and to detachably support the heating unit; a separation plate supported by the housing and disposed downstream of the fixing nip portion in a conveying direction of the recording material, the separation plate being configured to separate the recording material from the first rotating member without contacting the first rotating member; a guide portion configured to guide the heating unit in an attachment direction from an insertion start position to an attachment position to attach the heating unit to the housing in a case where the heating unit is to be attached to the housing so that the first rotating member is located at the fixing nip portion; and a cover attached to the housing and configured to rotate about a rotation axis to open and close the guide portion, the rotation axis being disposed downstream of the fixing nip portion in a conveying direction of the recording material, Here, the attaching direction is a direction along the conveying direction of the recording material nipped by the fixing nip portion.

2. The fixing device according to claim 1, wherein: The cover is configured to move between a first position and a second position by rotation, wherein the first position is a position in which the cover covers the heating unit at the attachment position, and the second position is a position in which the cover is retracted from a movable area of ​​the heating unit and the heating unit can be attached to or removed from the housing, and the movable area is an area in which the heating unit can move between an insertion start position and an attachment position.

3. The fixing device according to claim 2, in, The cover comprises a shielding portion which is located upstream of the heating unit in the attachment direction in the first position, and Here, the position of the shielding portion when the cover is located in the second position is located downstream in the attachment direction compared to the position of the shielding portion when the cover is located in the first position.

4. The fixing device according to claim 2 or 3, in, The guide portion includes a positioning portion configured to position the heating unit to an attachment position by abutment, and The cover includes a pressing portion, which is configured to abut the heating unit located at the attachment position when in the first position, and press the heating unit downstream in the attachment direction to position the heating unit at the positioning portion.

5. The fixing device according to claim 4, in, The heating unit includes a first abutment surface against which the pressing portion abuts in a state in which the heating unit is located at the attachment position and the cover is located at the first position, and The first abutting surface forms an angle with the attachment direction that is greater than 45 degrees and less than 90 degrees.

6. The fixing device according to claim 5, in, the heating unit includes a second abutment surface, the pressing portion abuts against the second abutment surface before abutting against the first abutment surface in a state where the heating unit is located at the attachment position and the cover is moved from the second position to the first position, and The second abutting surface is arranged along the attachment direction and is formed continuously with the first abutting surface.

7. The fixing device according to claim 2 or 3, in, The cover includes a contact portion, wherein the contact portion is configured to abut against the first rotating member of the heating unit located at the attachment position in a state where the cover is located at the first position, and The contact portion is configured to be separated from the first rotating member of the heating unit located at the attachment position in a state where the cover is located at the second position.

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