JP2010128223A - Image heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image heater capable of enhancing replacement workability and disassembling performance and reassembling performance while securing the high precision of a heating nip of a recording material and high reproducibility after the replacement/reassembling a pressure belt unit. <P>SOLUTION: A rotary shaft 42 is a parallel pin fixed to an upper unit frame body 40, and inserted slidably into a pin hole formed at a lower unit frame body 20. An engagement pin 41 for prohibiting an opening operation of the upper unit frame body 40 around the rotary shaft 42 as the center at an opposite side of the rotary shaft 42 is a parallel pin fixed to the upper unit frame body 40, and inserted slidably into the pin hole 20a. The engagement pin 41 comes off from the pin hole 20a when sliding the upper unit frame body 40 in a direction along the rotary shaft 42 with respect to the lower unit frame body 20 to release the upper unit frame body 40 around the rotary shaft 42 as the center. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image heating apparatus that forms a heating nip of a recording material by press-contacting a contactable / separable first rotating body and a second rotating body. The present invention relates to a frame opening / closing structure for access.

  2. Description of the Related Art An electrophotographic image forming apparatus equipped with an image heating apparatus that forms a heating nip of a recording material by pressing a first rotating body (roller or belt) and a second rotating body (roller or belt) is widely used. Yes.

  In the image heating apparatus, it is necessary to access the second rotating body from the side of the first rotating body with the heating nip greatly opened for the purpose of inspecting, cleaning, replacing, removing jammed sheets, and the like of the second rotating body.

  Patent Document 1 discloses a fixing device that forms a toner image fixing nip by pressing a fixing roller, which is an example of a first rotating body, and a pressure roller, which is an example of a second rotating body. Here, the pressure side frame that rotatably supports the pressure roller with respect to the fixing side frame that rotatably supports the fixing roller is assembled so as to be openable and closable around a predetermined rotation axis.

  Patent Document 2 discloses a fixing device that forms a toner image fixing nip by pressing a fixing belt, which is an example of a first rotating body, and a pressure belt, which is an example of a second rotating body. Here, a contact / separation mechanism for releasing the fixing nip by separating the pressure belt downward with respect to the fixing belt is shown, and the fixing nip is formed by raising the pressure belt every time the recording material is loaded during image formation. ing.

JP 2006-267865 A JP 2004-341346 A

  In the fixing device of Patent Document 1, the fixing side frame that can rotate around a predetermined rotation axis and the rotation end side of the pressure side frame are screwed in the opening and closing direction. For this reason, the screw positioning accuracy and tightening state may cause the parallelism between the fixing roller and the pressure roller to be out of order, or the pressure distribution in the longitudinal direction of the fixing nip may be uneven.

  In the fixing device of Patent Document 2, if the fixing side frame supporting the fixing belt unit is removed upward, the pressure belt unit held by the lower pressure side frame can be taken out upward. However, when such a frame opening / closing structure is adopted, the number of screws is increased as compared with the fixing device of Patent Document 1 whose one end is a rotating shaft, so that the reproducibility of the fixing nip after disassembly / reassembly is deteriorated.

  Although not shown in Patent Document 1, normally, the fixing roller and the pressure roller are connected by a gear train, and a gear on the fixing roller side and a gear on the pressure roller side are associated with the opening of the fixing nip. And release the mesh. When reassembling, the fixing roller side gear and the pressure roller side gear are engaged with each other in the process of closing the fixing side frame and the pressure side frame. However, when the fixing roller side gear and the pressure roller side gear abut against each other at the tooth tip when they are closed, the fixing side frame and the pressure side frame cannot be closed. If the collided tooth tip is damaged and metal powder is generated, it may adhere to the fixing roller and impair image quality.

  SUMMARY OF THE INVENTION A first object of the present invention is an image heating apparatus having a housing structure that has improved exchange workability and disassembly / reassembly while ensuring high accuracy of the heating nip of the recording material and reproducibility after reassembly. Is to provide.

  According to a second object of the present invention, the meshing of the gear on the first rotating body and the gear on the second rotating body can be smoothly attached and detached as the heating nip of the first rotating body and the second rotating body is opened and closed. An image heating apparatus is provided.

  The image heating apparatus according to the present invention includes a first rotating body rotatably supported by a first frame and a second frame rotatably supported by the first frame, and press-contacting the first rotating body to form a heating nip for a recording material. And a separating mechanism for separating the first rotating body and the second rotating body so as to release the heating nip. The first frame can be opened and closed around a predetermined rotation axis until the second rotating body can be taken out from the second frame, and the heating nip is released by the separation mechanism. A rotation mechanism capable of slidingly moving the first frame along the predetermined rotation axis, and the predetermined rotation axis along with the sliding movement of the first frame along the predetermined rotation axis. And an engaging member that fixes the positional relationship by engaging the first frame with the second frame at a position away from the first frame.

  In the image heating apparatus of the present invention, when the first frame is moved along the predetermined rotation axis, the engagement between the first frame and the second frame is released, and the first frame is moved relative to the second frame. It can be opened and closed. By rotating the first frame around a predetermined rotation axis to open the space between the second frame and the second rotation body, an access path to the second rotation body or a space for taking out the second rotation body is secured.

  After completion of the work, the first frame is rotated around a predetermined rotation axis to close the interval between the second frames. After that, by moving the first frame to the initial position along a predetermined rotation axis, the engagement between the first frame and the second frame is recovered, and the first frame is the first to the second frame. It is positioned and fixed as follows.

  Accordingly, it is possible to improve the exchange workability and the disassembly / reassembly of the image heating apparatus, and to ensure high accuracy of the recording material heating nip and reproducibility after the disassembly / reassembly.

  Prior to the opening operation of the first frame with respect to the second frame, the first frame slides along a predetermined rotation axis, and the first frame is determined after the closing operation of the first frame with respect to the second frame. It slides in the reverse direction along the rotation axis. For this reason, it is possible to adopt a configuration in which the gear on the first rotating body side and the gear on the second rotating body side are attached and detached in the tooth width direction along with the sliding movement in both directions along the predetermined rotation axis. When such a configuration is adopted, the tooth tips of the gear do not collide during the movement process of the gears in the inter-axis distance direction accompanying the frame opening / closing operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is another implementation in which part or all of the configuration of the embodiment is replaced with the alternative configuration as long as the frame can be opened around the rotation axis by movement along the rotation axis. It can also be implemented in the form.

  In this embodiment, a belt heating type fixing device will be described as the image heating device. However, the present invention can also be implemented by a roller heating type, belt-roller heating type fixing device, and an image surface gloss processing device.

  In the present embodiment, an image forming apparatus that transfers a toner image from a photosensitive drum to a recording material in a sheet-fed manner will be described. However, the present invention can be implemented.

  In the present embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention includes a printer, various printing machines, a copier, a fax machine, a composite machine, in addition to necessary equipment, equipment, and a housing structure. It can be implemented in various applications such as a machine.

  In addition, about the structure of the image forming apparatus shown by patent document 1, 2 and the general matter regarding control of an image heating apparatus, illustration is abbreviate | omitted and the overlapping description is abbreviate | omitted.

<Image forming apparatus>
FIG. 1 is an explanatory diagram of a configuration of the image forming apparatus according to the embodiment.

  As shown in FIG. 1, the image forming apparatus 100 is a laser beam printer that transfers a toner image onto a recording material using an electrophotographic process and heat-fixes the toner image onto the recording material with a fixing device 110.

  In the image forming apparatus 100, a charging roller 102, an exposure device 103, a developing device 104, and a transfer roller 105 are arranged around a rotating photosensitive drum 101.

  The photosensitive drum 101 is a rotating drum type electrophotographic photosensitive member, and is driven to rotate at a predetermined peripheral speed in the direction of arrow R1. The photosensitive drum 101 is formed of a photosensitive material such as OPC or amorphous silicon on a cylindrical substrate such as aluminum or nickel.

  The charging roller 102 is driven to rotate in contact with the photosensitive drum 101 and is applied with an oscillating voltage obtained by superimposing an AC voltage on a DC voltage from a power source (not shown), so that the surface of the photosensitive drum 101 has a uniform negative polarity. Charge to dark part potential VD.

  The exposure device 103 scans a laser beam that is ON-OFF modulated in accordance with an image signal obtained by developing the image data, and forms an electrostatic image of the image on the surface of the photosensitive drum 101. The exposed portion is uncharged by the laser beam and the potential is lowered to the bright portion potential VL.

  The developing device 104 magnetically carries a one-component developer charged to a negative polarity on a developing sleeve and rubs the photosensitive drum 101 with a magnetic spike of the one-component developer. A toner charged negatively in a portion of the light portion potential VL having a relatively positive polarity by applying an oscillating voltage obtained by superimposing an AC voltage to a negative DC voltage Vdc from a power source (not shown) to the developing sleeve. The electrostatic image is reversed and developed.

  The transfer roller 105 is driven to rotate and rotates in the width direction with the photosensitive drum 101, and forms a transfer nip T <b> 1 where the recording material P is nipped and conveyed while being pressed against the photosensitive drum 101. By applying a positive voltage from a transfer power source (not shown) to the transfer roller 105, the toner image charged to the negative polarity and carried on the photosensitive drum 101 is transferred to the recording material P that is nipped and conveyed through the transfer nip T1. The

  The recording material P is taken out from the cassette 106 by the paper feed roller 107, waits at the registration roller 108, and is fed to the transfer nip T1 by the registration roller 108 in synchronization with the toner image on the photosensitive drum 101.

  The recording material P, to which the toner image is transferred at the transfer nip T1 and separated from the photosensitive drum 101, is conveyed to the fixing device 110. The fixing device 110 heats and pressurizes the recording material P carrying an unfixed toner image to fix the toner image on the recording material P to form a permanent image. The recording material P on which the image is fixed is discharged and stacked on a discharge tray 112 on the casing by a discharge roller 111.

<Fixing device>
FIG. 2 is an explanatory diagram of the configuration of the fixing device.

  As shown in FIG. 2, in the fixing device 110, the pressure belt 13 is brought into pressure contact with the fixing belt 30 to form a fixing nip for nipping and conveying the recording material while heating. The fixing device 110 is rotatably supported by the first rotating body (30) supported by the first frame (40) and the second frame (20). And a second rotating body (13) that forms a heating nip. In addition, a separation mechanism (24) for separating the first rotating body and the second rotating body so as to release the heating nip is provided.

  The fixing belt 30 is wound around a fixing roller 31 and a fixing tension roller 32 and rotates. The fixing belt 30 is endlessly formed of a heat-resistant material that can generate heat by the induction heating coil 35.

  When an alternating current is passed through the induction heating coil 35, magnetic lines of force are generated around the coil, and an eddy current is generated in the metal layer of the fixing belt 30. The fixing belt 30 is heated by converting the eddy current into Joule heat by the resistance of the metal layer and generating heat in the metal layer.

  A thermistor is disposed on the inner surface of the fixing belt 30. A temperature control unit (not shown) detects the temperature of the fixing belt 30 based on the output signal of the thermistor and controls the output of the induction heating coil 35 so that the temperature of the fixing belt 30 becomes 180 ° C.

  The pressure belt 13 is wound around the pressure roller 14 and the pressure tension roller 15 and rotates.

  A halogen lamp heater (not shown) is arranged inside the pressure roller 14 as a heating element to heat the pressure belt 13 from the inside.

  A contact type thermistor is disposed in contact with the outer peripheral surface of the pressure belt 13. A temperature control unit (not shown) detects the temperature of the pressure belt 13 based on the output signal of the thermistor, and controls the output of the halogen lamp heater so that the surface temperature of the pressure belt 13 becomes 100 ° C.

  The fixing belt 30 is formed by coating a magnetic metal layer such as a nickel metal layer or a stainless steel layer having a thickness of 100 μm, a width of 380 mm, and a circumferential length of 200 mm with a silicon rubber having a thickness of 500 μm, and covering a surface layer with a PFA tube.

  The fixing roller 31 is formed by integrally molding a heat-resistant silicone rubber elastic layer on the surface of a metal core having an outer diameter of a solid stainless steel of φ19 mm.

  The fixing tension roller 32 is a hollow roller made of a stainless material and having an outer diameter φ20 and an inner diameter φ16. The fixing tension roller 32 is urged outward by a tension urging spring to maintain the belt tension of the fixing belt 30 at 120N.

  A fixing pad 37 made of a stainless material is disposed inside the fixing belt 30 upstream of the fixing roller 31. The fixing pad 37 is pressed against the pressure pad 18 that supports the inner surface of the pressure belt 13 with a set pressure 400N.

  The pressure roller 14 is a hollow rod made of stainless steel and has an outer diameter of about 21 mm and an inner diameter of about 19 mm.

  The pressure tension roller 15 is a hollow roller formed of a stainless material with an outer diameter of about 22 mm and an inner diameter of about 20 mm. The pressure tension roller 15 is urged outward by a tension urging spring to maintain the belt tension of the pressure belt 13 at 100N.

  A pressure pad 18 made of silicon rubber is disposed inside the pressure belt 13 on the upstream side of the pressure roller 14. The pressure pad 18 is pressed against the fixing pad 37 that supports the inner surface of the fixing belt 30 with a set pressure 400N.

  In the fixing device 110 configured as described above, the pressure roller 14 and the pressure pad 18 are in pressure contact with the fixing roller 31 and the fixing pad 37, respectively, via the overlap of the fixing belt 30 and the pressure belt 13. At this time, the surface silicon rubber layers of the fixing belt 30 and the pressure belt 13 are elastically deformed to form a fixing nip that is continuous in the conveying direction. In the process in which the recording material to which the toner image is transferred passes through the fixing nip, the toner image is fixed on the recording material.

  In the vicinity of the fixing belt 30, a separation member 50 for assisting the separation of the recording material from the fixing belt 30 is disposed. After the toner image is fixed, the recording material to be rotated without being separated from the curvature of the fixing belt 30 is forcibly separated from the fixing belt 30 by the separation member 50.

  Since the pressure belt unit 27 is often a consumable part and needs to be replaced in the market, the housing structure of the fixing device 110 needs to be designed in consideration of the replacement workability.

  In addition, since the accuracy of the nip pressure of the fixing nip is an important factor for obtaining a high-quality image, the housing structure of the fixing device 110 needs to improve the accuracy of the nip pressure.

  It is also necessary to reliably avoid the occurrence of scratches due to the contact between the separation member and the fixing belt during the replacement operation.

<Pressure belt unit removal structure>
FIG. 3 is an explanatory view of the disassembling structure of the fixing device, and FIG. 4 is an explanatory view of the work of taking out the pressure roller unit.

  As shown in FIG. 2, the pressure roller 14 and the pressure tension roller 15 are moved up and down integrally by the rotation of the pressure cam 24, and the pressure belt 13 is pressed against / separated from the fixing belt 30. To form / release the fixing nip.

  The lower unit frame 20 forms a U-shaped column structure (see FIG. 5) that surrounds the outside of the pressure belt 13 from the lower unit base 21 and stands at four corners.

  A pair of front and rear rotating plates 25 supported by a rotating shaft 26 disposed on the downstream side of the lower unit frame 20 rotates a pair of front and rear pressure cams 24 provided on the lower unit base 21. Then, the rotating end where the pressure spring pair 23 is arranged is moved up and down integrally.

  The rotating plate pair 25 supports the rotating end of the arm pair 22 that can rotate around the same rotating shaft 26 from below via the pressure spring pair 23. The pressure roller 14 and the pressure tension roller 15 over which the pressure belt 13 is stretched are supported at respective shaft ends with respect to the pair of front and rear arms 22.

  Therefore, when the pressure cam 24 disposed on the lower unit base 21 is rotated, the rotating plate pair 25 is rotated upward around the rotation shaft 26 to push up the lower end of the pressure spring pair 23. When the upper end of the pressure spring pair 23 is pushed and the arm pair 22 rotates upward, the pressure roller 14 and the pressure tension roller 15 rise. As a result, the pressure belt is pressed against the fixing belt 30 to form a fixing nip to which a nip pressure is applied by the pressure spring pair 23. The nip pressure can be arbitrarily adjusted by rotating the adjusting screw 44 to change the upper end position of the pressure spring pair 23.

  At the time of image formation, the pressure belt 13 and the fixing belt 30 are rotated at a distance from each other and are adjusted to different temperatures. When the pressure cam 24 rotates in synchronization with the recording material entering, the pressure belt 13 and the fixing belt 30 come into pressure contact to form a fixing nip. After the recording material is output, the pressure cam 24 rotates again. Then, the pressure belt 13 and the fixing belt 30 are separated.

  The pair of rotating plates 25, the pair of pressure springs 23, the pair of arms 22, the pressure roller 14, the pressure tension roller 15, and the pressure belt 13 constitute a pressure belt unit 27 as a replacement part assembled integrally. . The pressure belt unit 27 is configured to be separated from the lower unit base 21 and can be replaced as a consumable unit.

  On the other hand, the fixing roller 31 and the fixing tension roller 32 that are wound around the fixing belt 30 are supported by the upper unit frame body 40 at respective shaft ends. The upper unit frame body 40 can be rotated upward around a predetermined rotation shaft 42 disposed on the upstream side of the lower unit frame body 20 to open and close the space between the upper unit frame body 40 and the pressure belt unit 27.

  As shown in FIG. 3A, the upper unit frame 40 slides in the direction perpendicular to the paper surface and the pair of front and rear engaging pins 41 are released, so that the upper unit frame 40 is It can be opened and closed around a predetermined rotation axis 42.

  As shown in FIG. 3B, the upper unit frame body 40 can be opened in the direction of the arrow R <b> 2 around a predetermined rotation shaft 42, thereby opening the gap with the lower unit frame body 20. it can.

  As shown in FIG. 4, when the upper unit frame 40 is rotated and released from the lower unit frame 20, when the engagement between the rotation shaft 26 and the rotation hole 26 a is released, the lower unit frame 20. The pressure belt unit 27 is taken out upward.

<Engagement pin>
FIG. 5 is an explanatory view of the planar arrangement of the engaging pins, FIG. 6 is an explanatory view of the arrangement of a gear train for interlocking the fixing roller and the pressure roller, and FIG.

  As shown in FIG. 5A, the upper unit frame body 40 can be slid in the direction along the predetermined rotation axis 42 with respect to the lower unit frame body 20 by removing the set screw 43. .

  The rotating shaft 42 is a stainless steel parallel pin having a ring groove formed on the tip side, and is fixed to the upper unit frame body 40 and slidably inserted into a pin hole formed in the lower unit frame body 20. ing. In the ring groove, a C-ring 44 is fixed to prevent the drop-out from the lower unit frame 20.

  The engagement pin 41 that restrains the rotation of the upper unit frame 40 on the opposite side of the rotation shaft 42 is a parallel pin, and is fixed to the upper unit frame 40 and formed on the lower unit frame 20. The pin hole 20a is slidably inserted.

  As shown in FIG. 5B, the length of the engagement pin 41 is shorter than the movable distance α of the upper unit frame body 40 that is regulated by the C ring 44. For this reason, when the upper unit frame 40 is slid in the direction along the predetermined rotation shaft 42 until the C ring 44 comes into contact with the lower unit frame 20, the engagement pin 41 comes out of the pin hole 20a and is engaged. Is released. Thereby, as shown in FIG. 4, the upper unit frame body 40 can be rotated upward to open an interval from the pressure belt unit 27 held by the lower unit frame body 20.

  As shown in FIG. 6, gears 71 a to 71 f for interlocking the pressure roller 14 and the fixing roller 31 are arranged inside the lower unit frame 20 on the back side of the fixing device 110. A driving input gear for receiving rotational driving from the main body side of the image forming apparatus (100: FIG. 1) is disposed on the side opposite to the gear 71a of the fixing roller 31. The rotation of the drive input gear rotates the fixing roller 31 and is transmitted to the pressure roller 14 via the gears 71a to 71f.

  Since the gear 71d is arranged coaxially with the rotation shaft 26 of the pressure belt unit 27, when the pressure cam 24 is rotated to raise and lower the pressure belt unit 27, the gear 71d is engaged with the gear 71c. It does not change.

  However, the gears 71 a to 71 c are disposed on the upper unit frame body 40, while the gears 71 d to 71 e are disposed on the pressure belt unit 27. For this reason, when the upper unit frame 40 is rotated around the predetermined rotation shaft 42, the inter-axis distance between the gear 71d and the gear 71c changes. As shown in FIG. 3A, when the upper unit frame 40 is closed in a state where the pressure belt unit 27 is held inside the lower unit frame 20, the tooth tips of the gear 71d and the gear 71c collide with each other. there is a possibility.

  Therefore, the meshing width of the gear 71d and the gear 71c is made shorter than the movable distance α of the upper unit frame body 40 regulated by the C ring 44, and during the rotation of the upper unit frame body 40, The meshing with the gear 71c is released.

  As shown in FIG. 7A, in the engaged state, the meshing width of the gear 71d and the gear 71c is β.

  As shown in FIG. 7B, since the movable distance α of the upper unit frame 40 is larger than the meshing width β, the gear 71d and the gear 71c are separated from each other in the axial direction in the disengaged state. is doing. For this reason, when the upper unit frame 40 is closed from (b) to (a) in FIG. 3 in the disengaged state, the gear 71d and the gear 71c do not collide.

  In the fixing device 110, the lower unit frame body 20 and the upper unit frame body 40 are engaged with the engagement pins 41 of the upper unit frame body 40 and the predetermined rotation shaft 42 in four holes provided in the lower unit frame body 20. It is positioned by joining. Since positioning is performed by the shaft disposed on the side surface of the upper unit frame body 40 and the hole formed in the lower unit frame body 20, it is possible to ensure a very high positioning accuracy of both frame bodies. Further, since the lower unit frame body 20 and the upper unit frame body 40 are fixed only by the two set screws 43 in the vicinity of the engaging pin 41, disassembly and reassembly are easy.

<Separation member>
FIG. 8 is an explanatory view of the separating member retracting mechanism, and FIG. 9 is a partially enlarged view of the retracting mechanism.

  If a defect occurs on the surface layer of the fixing belt 30, problems such as image streaks occur. Therefore, the separation member that peels the recording material from the fixing belt 30 is not contacted while the tip is brought close to the fixing belt. It is. However, at the moment when the engagement of the engagement pin 41 with the lower unit frame 20 is released, the lower unit frame 20 slightly falls within the range of rattling. At this time, the separation member 50 may collide with the fixing belt 30 to cause damage.

  Therefore, while the engaging pin 41 and the lower unit frame body 20 are engaged, the separation member 50 is greatly separated from the fixing belt 30 to a position where it does not contact the fixing belt 30 even if the lower unit frame body 20 falls. I am letting.

  As shown in FIG. 8A, the separating member 50 is disposed so as to be supported by the rotating shaft 51, and is urged by the torsion spring 53 in the direction approaching the fixing belt 30. The separation member 50 is formed by coating a fluororesin on the surface of an aluminum plate having a thickness of 0.5 mm. The front end of the separation member 50 is held at a position immediately before contacting the fixing belt 30 by a stopper 54 that restricts the rotation range of the separation member 50.

  As shown in FIG. 5B, in the process of sliding the upper unit frame 40 in the disengagement direction along the predetermined rotation axis 42 with respect to the lower unit frame 20, as shown in FIG. In addition, the separating member 50 moves in a direction to retract from the fixing belt 30. The rollers 45 provided on the upper unit frame 40 come into contact with the separation member 50, and as shown in FIGS. 9A to 9B, the separation member 50 is pushed down. As a result, the separation member 50 rotates about the rotation shaft 51 to increase the distance between the fixing belt 30 and the separation member 50 from when the fixing device 110 is used, and the engagement pin 41 is engaged with the lower unit frame 20. When the alignment is lost, the separating member 50 does not collide with the fixing belt 30.

<Pressure belt unit replacement procedure>
The configuration of this embodiment will be described according to the procedure for replacing the pressure belt unit 27 that is a consumable unit. The procedure for replacing the pressure belt unit 27 is as follows.

  As shown in FIG. 5A, the set screw 43 is removed, and the upper unit frame 40 is slid in the direction of the arrow shown in FIG. The sliding distance (α) is set larger than the meshing width (β) of the gears 71c and 71d shown in FIG. The length of the engaging pin 41 is designed to be shorter than the length of the predetermined rotation shaft 42 by the length γ so as to satisfy the relationship of α> γ> β. As a result, as shown in FIG. 7, after the meshing of the gears 71 c and 71 d is released by the slide movement, the restraint of the lower unit frame body 20 by the engaging pin 41 is released as shown in FIG. 5 (b). The

  The end position of the slide movement is determined by the C ring 44 fixed to the predetermined rotation shaft 42 coming into contact with the lower unit frame 20.

  Thereafter, as shown in FIG. 4, the upper unit frame body 40 is rotated by 150 ° around the predetermined rotation shaft 42, and the work for removing the pressure belt unit 27 upward is enabled.

  With the above configuration, it is possible to secure the positional accuracy of the lower unit frame body 20 and the upper unit frame body 40, which cause deterioration of the nip pressure accuracy, at a high level. At the same time, contact between the separation member 50 and the fixing belt 30, which has a high risk of occurrence in the operation of replacing the pressure belt unit 27 that is a consumable part, is avoided. In addition, it is possible to prevent the occurrence of cracks, chipping, and scratches due to the collision between the tooth tips of the gear train that transmits driving between the lower unit frame body 20 and the upper unit frame body 40.

<Example 2>
In the first embodiment, the belt type fixing device using the upper and lower belts has been described. However, the present invention is not limited to this.

In the second embodiment, the following configuration is adopted in the roller type fixing device as in the first embodiment.
(1) The first frame can be rotated by a predetermined rotation shaft until the second rotating body can be taken out from the second frame, and the heating nip is released by the separation mechanism, and the predetermined rotation is performed. A rotation mechanism capable of moving the first frame along the axis is provided.
(2) An engaging member that engages the first frame with the second frame at a position away from the predetermined rotation axis and fixes the positional relationship in the process of moving the first frame along the predetermined rotation axis. Prepare.
(3) a first gear disposed on the first frame side for rotating the first rotating body; and a second gear disposed on the second frame side for rotating the second rotating body.
(4) The first gear and the second gear are engaged in the tooth thickness direction in the moving process of the first frame in the engaging direction along the predetermined rotation axis.

  With the above configuration, the positional accuracy between the second frame and the first frame, which causes the nip pressure accuracy to deteriorate, can be secured at a high level. At the same time, there is a high risk of occurrence in the operation of replacing the second rotating body, which is a consumable part, due to a collision between the tooth tips of the gear train transmitting the drive between the first frame side and the second frame side. The generation of cracks, chips and scratches can be prevented.

1 is an explanatory diagram of a configuration of an image forming apparatus according to an embodiment. FIG. 3 is an explanatory diagram of a configuration of a fixing device. FIG. 4 is an explanatory diagram of an exploded structure of the fixing device. It is explanatory drawing of the taking-out operation | work of a pressure roller unit. It is explanatory drawing of the planar arrangement | positioning of an engagement pin. It is explanatory drawing of arrangement | positioning of the gear train which makes a fixing roller and a pressure roller interlock | cooperate. It is explanatory drawing of meshing | engagement of a gearwheel and meshing cancellation | release. It is explanatory drawing of the retracting mechanism of a separation member. It is the elements on larger scale of a evacuation mechanism.

Explanation of symbols

13 Pressure belt 14 Pressure roller 15 Pressure tension roller 18 Pressure pad 20 Lower unit frame 21 Lower unit base 22 Arm pair 23 Pressure spring 24 Pressure cam 25 Rotating plate pair 26 Rotating shaft 27 Pressure belt unit 30 fixing belt 31 fixing roller 32 fixing tension roller 35 induction heating coil 37 fixing pad 40 upper unit frame 41 engaging pin 42 predetermined rotating shaft 43 set screw 44 C ring 45 roller 50 separating member 51 rotating shaft 52 positioning shaft 53 Torsion springs 71a, 71b, 71c, 71d, 71e, 71f Gear 100 Image forming apparatus 110 Fixing apparatus

Claims (5)

A first rotating body rotatably supported by the first frame;
A second rotating body that is rotatably supported by the second frame and presses against the first rotating body to form a heating nip of the recording material;
An image heating apparatus comprising: a separation mechanism that separates the first rotating body and the second rotating body so as to release the heating nip.
In a state where the first frame can be opened and closed around a predetermined rotation axis until the second rotating body can be taken out from the second frame, and the heating nip is released by the separation mechanism, A rotation mechanism capable of slidingly moving the first frame along a predetermined rotation axis;
As the first frame slides along the predetermined rotation axis, the positional relationship is fixed by engaging the first frame with the second frame at a position away from the predetermined rotation axis. An image heating apparatus comprising: an engagement member. A first gear disposed on the first frame side for rotating the first rotating body;
A second gear disposed on the second frame side for rotating the second rotating body,
The first gear and the second gear are engaged in a tooth thickness direction as the first frame slides in the engagement direction along the predetermined rotation axis. The image heating apparatus according to 1. The predetermined rotation axis is disposed on the outer side of the second rotating body in the recording material conveyance direction, in parallel with the rotating axis of the second rotating body,
The said engaging member is a parallel pin arrange | positioned in parallel with the rotating shaft of a said 2nd rotary body on the opposite side to the said predetermined rotating shaft in the conveyance direction of a recording material. Image heating device. The second frame has a support structure that is erected at four corners on the outer side of the second rotating body so as to hold the second rotating body inside.
4. The image heating according to claim 3, wherein the predetermined rotation shaft is disposed on the support structure on the downstream side in the recording material conveyance direction, and the engagement member is disposed on the support structure on the upstream side. apparatus. A separating member that is pivotally attached to the support structure and separates a recording material, the tip of which is taken along with the first rotating body, from the first rotating body;
A spring member that biases the separation member toward the first rotating body;
A retracting mechanism for retracting the separation member from the first rotating body against the spring member as the first frame slides in the disengagement direction along the predetermined rotation axis. The image heating apparatus according to claim 1, wherein the image heating apparatus is characterized.

Images