JP5488155B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  A general fixing device in an image forming apparatus is a recording paper in which a nip area is formed by two rollers, a heating roller (heating member) and a pressure roller (pressure member), and a toner image is transferred to the nip area. The toner image is fixed on the medium by passing through (hereinafter referred to as the medium). Since the toner melts in the nip region of the fixing device, the adhesion between the heating roller and the media is increased by the melted toner, and there is a problem that the media is wound around the heating roller.

  In order to solve this problem, a technique has been proposed in which the separation claw is brought into contact with the surface of the heating roller.

  The separation claw is good in terms of prevention of media wrapping, but because it is in contact with the surface of the heating roller, it causes a streak-like scratch on the surface of the heating roller, which causes image defects (uneven gloss) on the media. Etc.) has been a problem for image forming apparatuses that require high image quality. As a technique in consideration of this point, a technique is proposed in which the separation claw is movable in the axial direction of the heating roller so that the separation claw is not always in contact with the same position of the heating roller (Patent Document 1, Patent Document). 2).

  Further, when a member having a low hardness (Asker-c hardness of 40 to 45 °) is used on the surface of the heating roller in order to cope with various kinds of media such as copy paper, glossy paper of thick paper, and printing paper, paper is passed. There is a problem in that the surface of the heating roller is damaged by the edge of the media, and the surface of the heating roller appears as an image defect on the media in the same manner as the separation claw. In order to solve this problem, a technique is also known in which the fixing device can be moved in the axial direction of the heating roller relative to the medium.

  Furthermore, in order to suppress both the scratches on the surface of the heating roller due to the separation claw and the scratches on the surface of the heating roller due to the media, the separation claw can be moved in the axial direction of the heating roller and the fixing device can be moved relative to the media. A technique that enables movement in the axial direction of the heating roller is also known.

JP-A-9-160390 JP 2007-72259 A

  However, the technology that enables the separation claw to be movable in the axial direction of the heating roller and also enables the fixing device to be moved in the axial direction of the heating roller relative to the medium is used in the fixing device that has moved relative to the media. Since the separation claw moves further, the position of the separation claw may not be appropriate with respect to the media, and the media may not be separated from the heating roller.

  Considering this point, it is conceivable to increase the number of separation claws, but increasing the number of separation claws has the disadvantage of increasing the risk of scratches caused by the nails.

  An object of the present invention is to provide a fixing device that suppresses scratches caused by a separation claw and a medium on a heating member and appropriately separates the medium from the heating member.

In order to achieve the above object, a fixing device according to the present invention includes:
A fixing device used in an image forming apparatus for fixing a toner image to a medium by a heating member and a pressure member,
A separation claw that contacts the heating member and separates the media from the heating member;
A separation claw holding portion for holding the separation claw and fixing the position of the separation claw relative to the heating member;
Fixing swinging means for swinging the heating member in the axial direction of the heating member ;
When the heating member moves beyond a normal swing range, the separation claw is separated from the heating member .

An image forming apparatus according to the present invention is
The fixing device is used.

  According to the fixing device and the image forming apparatus of the present invention, it is possible to suppress the scratches caused by the separation claw and the medium on the heating member and to appropriately separate the medium from the heating member.

1 is a configuration diagram showing an embodiment of an image forming apparatus using a fixing device of the present invention. FIG. 2 is a schematic top view showing a conventional fixing device, and FIG. 2A is a view showing a state where a oscillated heating roller is at the most front side. FIG. 2B is a diagram showing a state where the heating roller is at the innermost side. FIG. 10 is a schematic cross-sectional view of a conventional fixing device viewed from a direction orthogonal to a medium conveyance direction. FIG. 4 is a schematic top view showing the fixing device of the present invention, and FIG. 4A is a diagram showing a state where the heating roller is at the most front side during normal operation. FIG. 4B is a diagram illustrating a state in which the heating roller is at the innermost side during normal operation. It is a perspective view which shows the place which attached the separation nail to the separation nail holding part. FIG. 3 is a cross-sectional view of the fixing device as viewed from a direction orthogonal to a medium conveyance direction. FIG. 4 is a diagram illustrating a state in which the fixing device is pulled out from the image forming main body. FIG. 6 is a cross-sectional view of the fixing device showing where the concave portion and the convex portion are fitted when viewed from a direction orthogonal to the medium conveyance direction.

  An embodiment of the present invention will be described. The description in this column does not limit the technical scope of the claims or the meaning of terms. Further, the following definitive explanation in the embodiment of the present invention shows the best mode, and does not limit the meaning and technical scope of the terms of the present invention.

(Image forming device)
FIG. 1 is a configuration diagram showing an embodiment of an image forming apparatus using the fixing device of the present invention, and mainly includes an image reading device SC and an image forming unit A.

  The image reading device SC scans and exposes the document placed on the document table using the optical system of the document image scanning exposure device, and projects it onto a line image sensor such as a CCD sensor. The image projected on the line image sensor is converted into an analog signal, and after performing analog processing, A / D conversion, shading correction, image compression processing, etc. in the image processing unit, the scanning optical devices 3Y, 3M, 3C, 3K Is input.

  The image forming unit A includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-shaped intermediate transfer belt 6, a scanning optical device 3, a paper feeding device 20, and an electric unit including a control unit. CPE (not shown) etc. are comprised.

  The image forming unit 10Y that forms a yellow (Y) image includes a band electrode unit 2Y, a scanning optical device 3Y, a developing unit 4Y, and a cleaning unit 5Y disposed around a photosensitive drum 1Y as an image carrier. . An image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a band electrode unit 2M, a scanning optical device 3M, a developing unit 4M, and a cleaning unit 5M. The image forming unit 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image carrier, a band electrode unit 2C, a scanning optical device 3C, a developing unit 4C, and a cleaning unit 5C. The image forming unit 10K that forms a black (K) image includes a photosensitive drum 1K as an image carrier, a band electrode unit 2K, a scanning optical device 3K, a developing unit 4K, and a cleaning unit 5K.

  The band electrode unit 2Y and the scanning optical device 3Y, the band electrode unit 2M and the scanning optical device 3M, the band electrode unit 2C, the scanning optical device 3C, the band electrode unit 2K, and the scanning optical device 3K constitute a latent image forming unit.

  Reference numerals 4Y, 4M, 4C, and 4K denote developing units 4 that contain a two-component developer composed of a small particle size toner of yellow (Y), magenta (M), cyan (C), and black (K) and a carrier.

  The intermediate transfer belt 6 is an intermediate transfer body that temporarily holds the toner image developed by the developing unit 4, and is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred onto the rotating intermediate transfer belt 6 by the primary transfer units 7Y, 7M, 7C, and 7K, and a combined color image is obtained. It is formed.

  A recording medium (hereinafter referred to as a recording sheet) P accommodated in a sheet feeding cassette 21 of the sheet feeding device 20 is fed by a sheet feeding means (first sheet feeding unit) 22 and fed by sheet feeding rollers 23, 24, 25, 26, registration rollers (second paper feed unit) 27, etc., are conveyed to the secondary transfer means 9, and the color image is transferred onto the recording paper P.

  Note that the three-stage sheet feeding cassettes 21 arranged vertically in the vertical direction below the image forming unit A have substantially the same configuration. The three-stage sheet feeding means 22 has almost the same configuration. The sheet feeding cassette 21 and the sheet feeding means 22 are collectively referred to as a sheet feeding device 20.

  The recording paper P to which the color image has been transferred is sandwiched by the fixing device TP, and the color toner image (or toner image) on the recording paper P is fixed by applying heat and pressure to the recording paper P. The sheet is fixed on the upper side, sandwiched between the sheet discharge rollers 28 and placed on a sheet discharge tray 29 outside the apparatus.

  On the other hand, after the color image is transferred onto the recording paper P by the secondary transfer means 9, the residual toner is removed by the belt cleaning means 8 from the intermediate transfer belt 6 from which the recording paper P is separated by curvature.

  In the description of the image forming apparatus A, the color image formation has been described. However, the present invention includes a case of forming a monochrome image.

  A high voltage of 5 to 10 kV by a DC power source is applied to the corona wire of the band electrode unit 2, and a uniform constant potential is charged on the surface of the photosensitive drum 1.

  Laser light or the like is used for the exposure system of the scanning optical device 3, and the exposure amount is controlled by, for example, pulse width modulation.

  Next, before describing the fixing device according to the present invention, problems in the conventional fixing device will be described.

(Conventional fixing device)
FIG. 2 is a schematic top view showing a conventional fixing device TP1 in which the separation claw 51 is swung and the heating roller (heating member) 50 is swung. FIG. 2A is a diagram showing a state in which the heating roller 50 is closest to the user (the user side or the front side) during the fixing operation on the medium P, and FIG. It is a figure which shows the state which has the heating roller 50 in the back | inner side at the time of operation | movement. FIG. 3 is a schematic cross-sectional view of a conventional fixing device TP1 as seen from a direction orthogonal to the medium conveyance direction.

  In the conventional fixing device TP1 shown in FIGS. 2 and 3, since the surface of the heating roller 50 is scratched when the separation claw 51 is always in contact with the same position of the heating roller 50, the separation claw 51 is attached to the heating roller 50. It is swung in the axial direction. Further, the fixing device TP1 including the heating roller 50 is also swung in the axial direction of the heating roller 50 in order to suppress scratches on the surface of the heating roller 50 caused by the edge of the recording paper as a medium.

  A plurality of separation claws 51 are arranged in a separation claw holding portion 521 that holds the separation claws 51 according to the size of the recording paper P.

  As shown in FIG. 3, the separation claw 51 rotates around the axis J <b> 1 formed integrally with the separation claw 51 in the medium conveyance direction, and the separation claw tip is heated by the elastic member 53. It is pressed to contact

  In FIG. 2, the conventional fixing device TP1 is mounted so as to slide on the fixing substrate 56, and includes a cam CM1 provided on the fixing substrate 56 and a fixing swing configured by a motor (not shown) that drives the cam CM1. The moving means swings in the axial direction (X1 direction). A tension spring 54 biases the conventional fixing device TP1 toward the cam CM1.

  The means for swinging the separation claw holding portion 521 holding the separation claw 51 in the axial direction (X2 direction) is constituted by a cam CM2 and a motor (not shown) that drives the cam CM2, as in the fixing swinging means. The separation claw holder 521 is swung by the rotation of the cam CM2. Reference numeral 55 denotes a tension spring that urges the separation claw holder 521 toward the cam CM2.

  The separation claw holder 521 is incorporated in the conventional fixing device TP1, and the swinging means of the separation claw holder 521 is provided in the conventional fixing device TP1. As shown in FIG. 2B, when the conventional fixing device TP1 moves in the X1 direction to the maximum eccentric amount L1 of the cam CM1, and the separation claw holder 521 moves to the maximum eccentric amount L2 of the cam CM2, the separation is performed. The nail holder 521 moves a maximum of L1 + L2. In other words, a part of the separation claw 51 may be out of the position where the media P is separated, which may cause a problem of poor separation.

(Fixing device of the present invention)
Next, the fixing device TP of the present invention will be described. The fixing device TP of the present invention solves the problem of poor separation in the conventional fixing device TP1, and will be described below with reference to the drawings. Note that members having the same functions as those of the conventional fixing device TP1 described in FIGS. 2 and 3 are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 4 is a top view illustrating the fixing device TP according to the present invention. 4A is a diagram illustrating a state in which the heating roller (heating member) 50 is closest to the user (the user side or the front side) during the fixing operation on the medium P, and FIG. FIG. 6 is a diagram illustrating a state in which a heating roller is in the innermost side during a fixing operation on a medium.

  FIG. 5 is a perspective view showing the separation claw 51 attached to the separation claw holding portion 52, and FIG. 6 is a cross-sectional view of the fixing device TP as seen from a direction perpendicular to the medium transport direction.

  As described above, in order to prevent the separation claw 51 from damaging the surface of the heating roller 50 and prevent image defects from appearing on the medium P, the heating roller 50 and the separation claw 51 move relative to each other in the axial direction. There is a need to. Further, in order to prevent the edge of the medium P from damaging the surface of the heating roller 50 so that no image defect appears on the medium P, the medium P and the heating roller 50 need to move relatively in the axial direction. is there. In the present invention, focusing on this point, the position of the separation claw 51 is fixed, and only the heating roller 50 is moved in the axial direction.

  As shown in FIG. 4, the fixing device TP is placed so as to slide on the fixing substrate 56, and a lock lever 62 for fixing the fixing device TP is provided on the front side of the fixing device TP. The lock lever 62 rotates around the fulcrum J2, and the front side of the fixing device TP is locked by the lock member 63. Further, the lock lever 62 includes an elastic member 57 for urging the separation claw holding portion 52 against the back plate 58 of the image forming main body, and an elastic member 541 for urging the fixing device TP against the cam CM1 provided on the fixing substrate 56. Is provided. The fixing device TP is oscillated in the axial direction (X1 direction) by a fixing oscillating means including a cam CM1 and a motor (not shown) that drives the cam CM1.

  In FIG. 4A, the separation claw holder 52 is separated from the fixing device TP, and the relative position between the separation claw 51 and the medium is fixed. Further, the housing on the paper discharge side of the fixing device TP is provided with a fitting member 60 provided with a concave portion 59 so as to be fitted with a convex portion 61 provided on the separation claw holding portion 52.

  4 and 6 show a state in which the convex portion 61 does not fit into the concave portion 59. When not fitted, the tip of the separation claw 51 is in contact with the heating roller 50.

  As shown in FIG. 4A, the heating roller 50 is in the foremost side (user side or front side), or the heating roller 50 is in the backmost side as shown in FIG. 4B. Even in the state, the convex portion 61 does not fit into the concave portion 59, and the tip of the separation claw 51 is in contact with the heating roller 50.

  Thus, even when the fixing device TP is swinging, the separation claw holding portion 52 is fixed and the heating roller 50 is relatively swung, so that the tip of the separation claw is always on the surface of the heating roller at the same position. Generation of scratches due to contact can be suppressed.

  Next, a description will be given of a releasing unit in which the leading end of the separation claw 51 is separated from the heating roller 50 when the fixing device TP is pulled out from the image forming main body by jamming or the like.

  FIG. 7 is a diagram illustrating a state in which the fixing device TP is pulled out from the image forming main body. When the lock lever 62 is unlocked and the lock lever 62 rotates, the elastic members 57 and 541 also rotate simultaneously.

  When the fixing device TP is pulled out in this state, the concave portion 59 provided in the fitting member 60 and the convex portion 61 provided in the separation claw holding portion 52 are fitted in the middle. Even when the lock lever 62 is unlocked, the position of the separation claw holder 52 is pressed in the direction of the fitting member 60 while being restricted by the pressing force of an unillustrated elastic member (black arrow direction).

  FIG. 8 is a cross-sectional view of the fixing device TP showing where the concave portion 59 and the convex portion 61 are fitted, as seen from a direction orthogonal to the medium transport direction.

  That is, when the movement of the fixing device TP exceeds the normal swing range, the concave portion 59 and the convex portion 61 are fitted, and the separation claw 51 releases the contact from the heating roller 50. When the fixing device TP is pulled out from the image forming main body, the separation claw holder 52 is also pulled out at the same time, so that jam processing can be easily performed.

  As described above, when the image forming apparatus is in operation, the separation claw 51 does not swing, and only the heating roller 50 (the fixing device TP in the present embodiment) is moved in the axial direction, so that the separation claw 51 or the heating roller by the medium is used. The occurrence of scratches on the surface is suppressed.

  Further, since the separation claw 51 does not need to move with respect to the media, the media can be properly separated from the heating roller.

  Further, the separation claw holding part 52 is only pressed against the machine main body by the elastic member 57 (see FIG. 4), and does not have any special moving means, which is advantageous in terms of cost.

  In this embodiment, the heating roller 50 is moved together with the fixing device TP, but the same effect can be obtained by moving only the heating roller 50. Further, although the heating roller has been described, the same effect can be obtained even with a fixing belt.

  Furthermore, the heating roller 50 is a metal pipe made of aluminum or the like coated with a highly peelable tetrafluoroethylene perfluoroalkoxyethylene resin (PFA) or the like, or an elastic member such as rubber is wrapped around the metal pipe, and further a PFA tube. It may be a material in which is inserted.

  As a material of the separation claw 51, a resin material that can withstand a fixing temperature (about 150 ° C. to 220 ° C.), for example, a polyallyl ether ketone (PAEK) material or the like is used.

DESCRIPTION OF SYMBOLS 50 Heating roller 51 Separation claw 52,521 Separation claw holding | maintenance part 56 Fixing board | substrate 59 Concave part 60 Fitting member 61 Convex part TP Fixing device TP1 Conventional fixing device

Claims (4)

A fixing device used in an image forming apparatus for fixing a toner image to a medium by a heating member and a pressure member,
A separation claw that contacts the heating member and separates the media from the heating member;
A separation claw holding portion for holding the separation claw and fixing the position of the separation claw relative to the heating member;
Fixing swinging means for swinging the heating member in the axial direction of the heating member ;
The fixing device , wherein the separation claw is separated from the heating member when the heating member moves beyond a normal swinging range .   The fixing device according to claim 1, wherein the swinging operation of the heating member in the axial direction is performed by swinging the fixing device. The separation pawl holding unit, when the fixing device is withdrawn from the image forming apparatus, a fixing device according to claim 1 or 2, characterized in that the drawn simultaneously. An image forming apparatus characterized by using the fixing device according to any one of claims 1 to 3.

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