JP2014191039A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which is capable of adjusting pressure exerted to a recording medium by the recording medium itself and an image forming apparatus.SOLUTION: The fixing device includes a rotating body 64, an endless belt 66 revolving while holding a recording medium P between the endless belt 66 and the rotating body 64, and a pressure member 80 arranged along the rotation axis direction of the rotating body 64 on the inner peripheral side of the endless belt 66 and pressurizing the endless belt 66 toward the rotating body 64. The pressure member 80 has a first position where the pressure member 80 comes into contact with the rotating body 64 through the endless belt 66 and a second position where the pressure member 80 does not come into contact with the rotating body 64. The pressure member 80 comes into contact with the rotating body 64 through the recording medium P and the endless belt 66 in the second position, when the recording medium P is conveyed.

Description

  The present invention relates to a fixing device and an image forming apparatus.

In an image forming apparatus such as a copying machine or a printer, for example, a toner image is transferred onto a recording medium, and the transferred toner image is fixed by heating and pressing with a fixing device to form an image. Wrinkles, wrinkles, etc. may occur in envelopes that are thicker than plain paper.
A fixing device and an image forming apparatus in which wrinkles, wrinkles, and the like are suppressed by changing a conveyance path are known (for example, see Patent Document 1).
Also, a fixing device that adjusts the pressure exerted on the recording medium according to the type of the recording medium is known (see, for example, Patent Document 2).
Furthermore, the pressing member that presses against the heating roller has a soft pad and a hard pad, a standard mode that presses the soft pad and the hard pad with full pressure, and a special mode that presses only the soft pad toward the heating roller. There is known an image forming apparatus provided with a pressure switching mechanism for switching between them (for example, see Patent Document 3).

JP 2012-13875 A JP 2009-163188 A JP 2008-233133 A

  An object of the present invention is to provide a fixing device and an image forming apparatus that can adjust the pressure exerted on the recording medium by the recording medium.

  According to the first aspect of the present invention, a rotating body, an endless belt that circulates with a recording medium sandwiched between the rotating body, and an inner peripheral side of the endless belt are arranged along the rotation axis direction of the rotating body. And a pressing member that pressurizes the endless belt toward the rotating body, the pressing member contacting the rotating body via the endless belt, and the rotating body. The pressure member has a second position that is non-contact, and the pressure member contacts the rotating body via the recording medium and the endless belt when the recording medium is conveyed at the second position. The fixing device characterized by the above.

  According to a second aspect of the present invention, the pressurizing member rotates the endless belt on the downstream side in the rotation direction with respect to the contact forming unit, the contact forming unit contacting the recording medium toward the rotating body. The fixing device according to claim 1, further comprising a pressure unit that pressurizes the body.

  According to a third aspect of the present invention, the second position is a position where the thin recording medium clogged between the conveying belt and the rotating body is removed. Item 3. The fixing device according to Item 2.

  According to a fourth aspect of the present invention, in the second position, a distance between the contact forming portion and the rotating body and a distance between the pressing portion and the rotating body are substantially the same distance. The fixing device according to claim 1, wherein the fixing device is set to a distance shorter than a thickness of the thick recording medium.

  According to a fifth aspect of the present invention, there is provided an image forming unit that transfers an unfixed toner image to a recording medium, and the unfixed toner image is fixed to the recording medium. An image forming apparatus comprising the fixing device described in 1. above.

  According to the first aspect of the present invention, the pressure exerted on the recording medium by the recording medium can be adjusted as compared with the case where the present configuration is not provided.

  According to the second aspect of the present invention, the pressure exerted on the recording medium by the recording medium can be adjusted as compared with the case where the present configuration is not provided.

  According to the third aspect of the present invention, the pressure exerted on the recording medium by the recording medium can be adjusted and the recording medium can be removed as compared with the case where this configuration is not provided.

  According to the fourth aspect of the present invention, the pressure exerted on the recording medium by the recording medium can be adjusted as compared with the case where this configuration is not provided.

  According to the fifth aspect of the present invention, the pressure exerted on the recording medium by the recording medium can be adjusted as compared with the case where the present configuration is not provided.

1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a perspective view of a heating roll and a pressure belt housed in a fixing device main body of the fixing device according to the embodiment. FIG. 3 is a schematic side view of a fixing device in which a pressure member is in a first position. FIG. 6 is a schematic side view of a fixing device in which a pressure member is in a second position. The schematic perspective view of a pressurization body.

  Below, an example of an embodiment concerning the present invention is described based on a drawing.

(Configuration of image forming apparatus 10)
First, the configuration of the image forming apparatus will be described. FIG. 1 is a schematic configuration diagram illustrating a configuration of an image forming apparatus 10 according to the embodiment. Note that an arrow UP shown in the drawing indicates a vertically upward direction.

  In FIG. 1, an image forming apparatus 10 includes an image forming apparatus main body 11 in which each component is housed. Inside the image forming apparatus main body 11, an accommodating portion 12 that accommodates a recording medium P such as paper, an image forming portion 14 that transfers a toner image that is an example of an unfixed toner image on the recording medium P, and undetermined And a fixing device 60 for fixing the received toner image to the recording medium P.

  Further, a transport unit 16 that transports the recording medium P from the storage unit 12 to the image forming unit 14 and a control unit 20 that controls the operation of each unit of the image forming apparatus 10 are provided. Further, a discharge unit 18 for discharging the recording medium P on which an image is formed by the image forming unit 14 is provided on the upper portion of the image forming apparatus main body 11.

  The image forming unit 14 includes image forming units 22Y, 22M, 22C, and 22K (hereinafter referred to as 22Y to 22K) that form toner images of colors of yellow (Y), magenta (M), cyan (C), and black (K). And an intermediate transfer belt 24 to which the toner images formed by the image forming units 22Y to 22K are transferred, and a first transfer roll for transferring the toner images formed by the image forming units 22Y to 22K to the intermediate transfer belt 24 26 and a second transfer roll 28 for transferring the toner image transferred to the intermediate transfer belt 24 by the first transfer roll 26 from the intermediate transfer belt 24 to the recording medium P. The image forming unit 14 is not limited to the above-described configuration, and may have another configuration as long as it transfers an unfixed toner image onto the recording medium P.

  The image forming units 22 </ b> Y to 22 </ b> K are arranged side by side at the center in the vertical direction of the image forming apparatus 10 while being inclined with respect to the horizontal direction. Each of the image forming units 22Y to 22K includes a photoreceptor 32 that rotates in one direction (for example, the clockwise direction in FIG. 1). Since the image forming units 22Y to 22K are configured in the same manner, the reference numerals of the respective parts of the image forming units 22M, 22C, and 22K are omitted in FIG.

  Around each photoconductor 32, in order from the upstream side in the rotation direction of the photoconductor 32, the charging roll 23 for charging the photoconductor 32 and the photoconductor 32 charged by the charge roll 23 are exposed to electrostatically adhere to the photoconductor 32. An exposure device 36 that forms a latent image, a developing device 38 that develops an electrostatic latent image formed on the photoconductor 32 by the exposure device 36 to form a toner image, and a photoconductor 32 that contacts the photoconductor 32. A removal member 40 for removing the remaining toner is provided.

  The exposure device 36 is configured to form an electrostatic latent image based on the image signal sent from the control unit 20. Examples of the image signal sent from the control unit 20 include an image signal acquired by the control unit 20 from an external device.

  The developing device 38 includes a developer supply body 38A that supplies the developer to the photoconductor 32, and a plurality of transport members 38B that transport the developer applied to the developer supply body 38A while stirring.

  The intermediate transfer belt 24 is formed in an annular shape and is disposed on the upper side of the image forming units 22Y to 22K. On the inner peripheral side of the intermediate transfer belt 24, winding rolls 42 and 44 around which the intermediate transfer belt 24 is wound are provided. The intermediate transfer belt 24 is circulated and moved in one direction (for example, counterclockwise in FIG. 1) while being in contact with the photosensitive member 32 when one of the winding rolls 42 and 44 is rotationally driven. Yes. The winding roll 42 is an opposing roll that faces the second transfer roll 28.

  The first transfer roll 26 faces the photoconductor 32 with the intermediate transfer belt 24 interposed therebetween. A space between the first transfer roll 26 and the photoconductor 32 is a first transfer position where the toner image formed on the photoconductor 32 is transferred to the intermediate transfer belt 24.

  The second transfer roll 28 faces the winding roll 42 with the intermediate transfer belt 24 interposed therebetween. A space between the second transfer roll 28 and the winding roll 42 is a second transfer position where the toner image transferred to the intermediate transfer belt 24 is transferred to the recording medium P.

  The transport unit 16 is disposed along the transport path 48 and is transported along a transport roll 48 for transporting the recording medium P stored in the storage section 12, a transport path 48 for transporting the recording medium P transported to the transport roll 46. There are provided a plurality of transport rolls 50 for transporting the recording medium P sent out by the roll 46 to the second transfer position.

  A fixing device 60 that fixes the toner image transferred to the recording medium P by the second transfer roll 28 to the recording medium P is provided on the downstream side in the transport direction from the second transfer position. Further, the fixing device 60 is provided with a discharge roll 52 that discharges the recording medium P on which the toner image is fixed to the discharge unit 18. A specific configuration of the fixing device 60 will be described later.

  Next, an image forming operation for forming an image on the recording medium P in the image forming apparatus 10 according to the present embodiment will be described.

  In the image forming apparatus 10 according to the embodiment, the recording medium P sent out from the storage unit 12 by the sending roll 46 is sent to the second transfer position by the plurality of conveying rolls 50.

  On the other hand, in the image forming units 22 </ b> Y to 22 </ b> K, the photosensitive member 32 charged by the charging roll 23 is exposed by the exposure device 36 to form an electrostatic latent image on the photosensitive member 32. The electrostatic latent image is developed by the developing device 38 to form a toner image on the photoreceptor 32. The color toner images formed by the image forming units 22Y to 22K are superimposed on the intermediate transfer belt 24 at the first transfer position to form a color image. Then, the color image formed on the intermediate transfer belt 24 is transferred to the recording medium P at the second transfer position.

  The recording medium P to which the toner image has been transferred is conveyed to the fixing device 60, and the transferred toner image is fixed by the fixing device 60. The recording medium P on which the toner image is fixed is discharged to the discharge unit 18 by the discharge roll 52. As described above, a series of image forming operations are performed.

(Configuration of Fixing Device 60)
In FIG. 1, a fixing device 60 according to the embodiment includes a fixing device main body 62 provided with each component. FIG. 2 is a perspective view of a heating roll 64 that is an example of a rotating body housed in a fixing device main body 62 of the fixing device 60 and a pressure belt 66 that is an example of an endless belt. FIG. A schematic side view of the fixing device 60 in which the member is in the first position is shown. FIG. 4 shows a schematic side view in which a pressure member described later is in the second position. FIG. 5 shows a schematic perspective view of the pressurizing body 82.

  The heating roll 64 rotates around the rotation axis AR. The rotation axis AR is indicated by a solid line double arrow. In FIG. 3, the conveyance path along which the recording medium P is conveyed by the heating roll 64 and the pressure belt 66 is indicated by a two-dot chain line.

  The fixing device 60 includes a heating roll 64, a pressure belt 66 that circulates with the recording medium P interposed between the heating rolls 64, and an inner peripheral side of the pressure belt 66 along the direction of the rotation axis AR of the heating roll 64. And a pressure member 80 that pressurizes the pressure belt 66 toward the heating roll 64.

  Further, the pressing member 80 contacts the recording medium P toward the heating roll 64, and applies the pressing belt 66 toward the heating roll 64 on the downstream side of the rotation direction of the contact forming section 82 A. And a pressurizing part 82B for pressing. When the thin recording medium P is conveyed by the pressure member 80, the pressure member 66 takes the first position where the pressure belt 66 is pressed against the heating roll 64 via the thin recording medium P, and the thickness d is thick. When the recording medium P is conveyed, the recording medium P moves in a direction away from the heating roll 64, and takes a second position where the pressure belt 66 is pressed against the heating roll 64 via the thick recording medium PT.

  The fixing device 60 includes a heating source 64B that heats at least one of the heating roll 64 and the pressure belt 66, and an unfixed toner image is formed in an area where the pressure belt 66 is pressed toward the heating roll 64. It is heated and fixed on the recording medium P. In the embodiment, the area to be pressurized is an area in which the pressure belt 66 is pressurized toward the heating roll 64 by the contact forming unit 82A and the pressure unit 82B. In the embodiment, the heating source 64B is provided inside the heating roll 64, but the pressure belt 66 may be heated by the heating source.

  The recording medium P conveyed by being sandwiched between the heating roll 64 and the pressure belt 66 is heated with the toner image by the heating roll 64 and pressurized with the heating roll 64. An image is fixed in a pressure region with the belt 66.

  Next, a specific configuration of the heating roll 64 and the pressure belt 66 and a support structure for the heating roll 64 and the pressure belt 66 will be described in detail.

  2 and 3, the heating roll 64 includes a cylindrical cylindrical member 64A and a heating source 64B such as a halogen lamp provided in the internal space of the cylindrical member 64A. The cylindrical member 64A is made of a metal material such as aluminum or stainless steel. A gear 64C for transmitting a rotational force from a drive motor (not shown) to the cylindrical member 64A is attached to one end of the cylindrical member 64A in the axial direction.

  2 and 3, the cylindrical member 64 </ b> A has both end portions in the axial direction as supported portions 64 </ b> D supported by the slide bearing 68.

  A covering member 64E that covers the outer peripheral surface of the cylindrical member 64A is provided between the supported portions 64D on both ends in the axial direction of the cylindrical member 64A. The covering member 64E is made of an elastic material such as rubber.

  The fixing device main body 62 shown in FIG. 1 is provided with a support 70 that supports the heating roll 64 and the pressure belt 66. The support 70 includes a roll support member 74 that supports the heating roll 64 and a belt support member 76 that supports the pressure belt 66.

  The roll support member 74 includes a pair of side plates 74A that are disposed on both axial ends of the heating roll 64 and support the heating roll 64, and a connection plate 74B that is disposed between the pair of side plates 74A and couples the pair of side plates 74A. I have.

  Slide bearings 68 are respectively attached to the pair of side plates 74A. The slide bearing 68 rotatably supports the supported portion 64D of the cylindrical member 64A.

  A shaft portion 74J that rotatably supports the belt support member 76 is provided at one end of the pair of side plates 74A.

  An attachment portion 74E to which one end portion of the tension spring 90 is attached is provided at the other end portion of the pair of side plates 74A. Specifically, the mounting portion 74E is formed of a recess formed in the pair of side plates 74A. A hook 90 </ b> A formed at one end of the tension spring 90 is hooked on the mounting portion 74 </ b> E configured by a recess.

  The belt support member 76 includes a pair of side plates 76 </ b> A disposed on both ends of the pressure belt 66 in the axial direction.

  The pressure belt 66 is supported by the belt support member 76 at a position facing the heating roll 64 so as to be able to go around the fixing device main body 62 shown in FIG. In the heating roll 64 and the pressure belt 66, the heating roll 64 is driven to rotate, and the pressure belt 66 is driven and rotated by the heating roll 64, so that the recording medium P onto which the toner image is transferred is sandwiched and conveyed. It has a configuration.

  An attachment portion 76C to which the other end portion of the tension spring 90 is attached is provided at the other end portion of the pair of side plates 76A. Specifically, the attachment portion 76C includes a through hole that penetrates the pair of side plates 76A. A hook 90 </ b> B formed on the other end of the tension spring 90 is hooked on the mounting portion 76 </ b> C configured by a through hole.

  Insertion grooves 76B into which the plate body 84 shown in FIG. 3 can be inserted are formed in the pair of side plates 76A.

  A lever 76D is formed on the side opposite to the attachment portion 76C formed on the one side plate 76A. In FIG. 3, when the lever 76D is pulled in the direction of the white arrow, the positions of the heating roll 64 and the pressure belt 66 can be changed from the first position to the second position against the tension spring 90.

  FIG. 4 is a schematic side view of the pressing member 80 in a state where the lever 76D is pulled in the direction of the white arrow, in the second position. Incidentally, FIG. 3 is a schematic side view of the pressing member 80 in the first position.

  In the embodiment, the heating roll 64 and the pressure belt 66 are separated from each other by pulling the lever 76D from the first position where the heating roll 64 and the pressure belt 66 are pressed by the force of the tension spring 90. Move the second position. A well-known method can be used as the fixing method at the second position. For example, the side plate 74A and the side plate 76A can be formed so as to stop at the second position, and a portion where the projection and the projection are fitted can be formed, and the position can be determined by fitting using the elasticity of the side plate 76A on one side. Also when returning to the first position, using the elasticity of the side plate 76A on one side, the fitting is released and the tension spring 90 returns the tension.

  Other examples of the method for moving the pressure member 80 to the second position include, but are not limited to, a method using rotation of a cam and a method using an electric step motor.

  In FIG. 3, when the pressing member 80 is in the first position, the heating roll 64 and the pressing belt 66 are in contact with each other. When the thin recording medium P is conveyed at this position, the thin recording medium P is taken in between the heating roll 64 and the pressure belt 66, and the thin recording medium P is recorded between the heating roll 64 and the pressure belt 66. The medium P is pressurized.

  On the other hand, in FIG. 4, when the pressure member 80 is in the second position, the pressure member 80 is separated from the heating roll 64. When the thick recording medium PT is conveyed at this position, the pressure member 80 is separated from the heating roll 64. However, since the recording medium PT is thick, it is thicker between the heating roll 64 and the pressure belt 66. Recording medium PT is taken in, and the thick recording medium PT is pressurized by the heating roll 64 and the pressure belt 66. Here, in order to press the thick recording medium PT, the distance between the contact forming portion 82A and the heating roll 64 and the pressing portion 82B and the heating roll 64 are determined based on the thickness d of the thick recording medium PT. Set the distance between to short.

  In the second position, the pressure member 80 moves away from the heating roll 64. However, in the thick recording medium PT, the thickness is fixed without applying pressure as much as the first position. . Therefore, it is possible to obtain the fixing device 60 that suppresses deterioration of fixing property and generation of wrinkles even when fixing a thick recording medium PT. For example, in the case of an envelope which is an example of a thick recording medium PT, there are sheets on the front and back, and wrinkles are likely to occur due to the speed difference between the front and back, but the pressure applied to the envelope in the first position is strong. In comparison, since the pressure applied to the envelope is weak, wrinkles are less likely to occur.

  The second position may be a position where the thin recording medium P clogged between the pressure belt 66 and the heating roll 64 is removed. As a result, the thick recording medium PT can be fixed at the position where the thin recording medium P is removed, and a decrease in fixing property and generation of wrinkles can be suppressed when fixing the thick recording medium PT. Thus, the fixing device 60 capable of removing the thin recording medium P is obtained.

(Configuration of the pressure member 80)
In FIG. 3, a pressure member 80 that pressurizes the pressure belt 66 to the heating roll 64 is disposed along the rotation axis AR of the pressure belt 66 on the inner periphery of the pressure belt 66. The pressurizing member 80 includes a pressurizing body 82 disposed on the heating roll 64 side, and a plate body 84 having an L shape in side view provided on the pressurizing body 82.

  In FIG. 5, the pressing body 82 has a length along the direction of the rotation axis AR of the heating roll 64 and is formed in a substantially rectangular shape (block shape) in a side view. On the heating roll 64 side of the pressurizing body 82, a contact forming portion 82A and a pressurizing portion 82B are formed. Here, although not shown in detail, the contact forming portion 82A and the pressurizing portion 82B are formed as contact surfaces.

  An insertion groove 82 </ b> C into which the plate body 84 is inserted is formed along the longitudinal direction of the pressure body 82 on the side away from the heating roll 64 of the pressure body 82. The insertion groove 82 </ b> C is disposed on the downstream side in the rotation direction of the pressure belt 66 in the pressure body 82. The plate body 84 has a length along the direction of the rotation axis AR of the heating roll 64.

  The pair of side plates 76A of the belt support member 76 shown in FIGS. 2 and 3 and the pair of side plates 74A of the roll support member 74 are pulled by the tension spring 90, whereby the pressure member 80 rotates the rotation shaft of the pressure belt 66. The pressure belt 66 is pressed against the heating roll 64 by applying a load (pressing force) at both ends in the AR direction.

  Since the pressurizing body 82 is applied with a pressing force F from the plate body 84 inserted into the insertion groove 82C, the pressurizing portion 82B causes the second pressurizing belt 66 to move to the second position in the portion where the insertion groove 82C is disposed. The pressure F is maximized. As a result, as shown in FIG. 5, the pressure F applied to the heating roll 64 of the pressure belt 66 is maximized at the pressure unit 82 </ b> B in a side view along the rotation axis direction of the pressure belt 66.

  The contact forming unit 82A is disposed on the upstream side in the transport direction with respect to the pressurizing unit 82B, and the pressurizing belt 66 is moved to the heating roll 64 so that the pressurizing belt 66 contacts the recording medium P with the heating roll 64. Pressurization is performed at a first pressure smaller than the second pressure. When the recording medium P is not present at the position where the contact forming portion 82A is disposed, there is a gap between the heating roll 64 and the pressure belt 66, or the heating roll 64 and the pressure belt 66 are in contact with each other. It is a state of not to do.

  In FIG. 4, at the second position, the distance between the contact forming portion 82A and the heating roll 64 and the distance between the pressing portion 82B and the heating roll 64 are substantially the same distance j, and the thicker recording is performed. It is preferable that the distance is shorter than the thickness d of the medium PT. At the first position, the thin recording medium P is mainly pressed by the contact forming portion 82A, whereas at the second position, the thick recording medium PT is pressed at two locations of the contact forming portion 82A and the pressing portion 82B. Since the fixing is performed under pressure, the fixing device 60 can be obtained in which deterioration of fixing property and fixing unevenness are suppressed.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made. For example, in the second position, the distance between the contact forming portion 82A and the heating roll 64 and the distance between the pressing portion 82B and the heating roll 64 are not limited to the substantially same distance j, but the contact forming portion 82A. The distance between the heating roll 64 and the pressure roller 82B and the heating roll 64 may be such that the thin recording medium P is removed and the thick recording medium PT can be pressurized. .

  DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 14 ... Image forming part, 60 ... Fixing device, 64 ... Heating roll which is an example of rotating body, 64B ... Heat source, 66 ... Pressure belt which is an example of endless belt, 80 ... Pressure member , 82A ... contact forming part, 82B ... pressure part, AR ... rotating shaft, P ... thin recording medium, PT ... thick recording medium, R ... rotational direction.

Claims (5)

A rotating body,
An endless belt that circulates around the recording medium between the rotating body,
A pressure member that is disposed along the rotation axis direction of the rotating body on the inner peripheral side of the endless belt, and pressurizes the endless belt toward the rotating body;
The pressure member has a first position in contact with the rotating body via the endless belt, and a second position in non-contact with the rotating body,
The fixing device, wherein the pressure member contacts the rotating body via the recording medium and the endless belt when the recording medium is conveyed at the second position.   The pressurizing member includes a contact forming unit that contacts the recording medium toward the rotating body, and a pressurizing unit that pressurizes the endless belt toward the rotating body on the downstream side of the contact forming unit in the rotation direction. The fixing device according to claim 1, further comprising: The fixing device according to claim 1, wherein the second position is a position from which the thin recording medium clogged between the conveyance belt and the rotating body is removed. In the second position, the distance between the contact forming portion and the rotating body and the distance between the pressing portion and the rotating body are substantially the same distance, and the thickness of the thicker recording medium The fixing device according to claim 1, wherein the fixing device is set to a shorter distance. An image forming unit that transfers an unfixed toner image to a recording medium;
An image forming apparatus comprising: the fixing device according to claim 1, wherein the unfixed toner image is fixed on the recording medium.

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