JP2006153937A - Separating device, carrying device, fixing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separating device which allows a front end part of a separating claw to be separated from the roller in the case of the occurrence of a jam so as to keep a good image quality and also to prevent breakdown of a roller, and provide a carrying device, a fixing device, and an image forming apparatus. <P>SOLUTION: A separating device 30 for separating a recording paper from a heat roller 21 is disposed downstream of a nip part between the heat roller 21 and a pressure roller 22, where the recording paper is held and carried, in a traveling direction of the recording paper and is between a passage path of the recording paper and the heat roller 21. The separating device 30 includes; a separating claw 31 which is rotatable around a revolving shaft 33 and has a front end, which is upstream of the revolving shaft 33 in the traveling direction of the recording paper, brought into contact with the surface of the heat roller 21; and a spur 32 projecting from a recording paper-side surface of the separating claw 31. A revolving shaft 34 of the spur 32 is disposed downstream of the revolving shaft 33 of the separating claw 31 in the traveling direction of the recording paper. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device that performs fixing by heating and pressurization, a separation device used in the fixing device, a transport device, and an image forming apparatus such as a printer and a copying machine that use the fixing device. More specifically, the present invention relates to a fixing device, a separating device, a conveying device, and an image forming device that fix a medium to be transferred by sandwiching between a heating roller and a pressure roller.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a copying machine or a printer has a fixing device for heating and pressing a recording material on which a toner image is formed to fix the toner to the recording material. . Such a fixing device has a heating roller and a pressure roller, and is known to perform fixing by passing the nip of the recording material through the nip. Further, many have a separating device for separating the recording material from these rollers.

  When a jam or the like of a recording material occurs in such an image forming apparatus, the jammed paper may accumulate on the exit side of the fixing device, and the jammed paper may press the separation claw of the separation device. In such a case, in the fixing device in which the separation claw is in contact with the heating roller or the pressure roller, the tip of the separation claw may bite into the roller. In particular, in a roller having an elastic layer on the surface, the elastic layer may be damaged.

  On the other hand, for example, in the fixing device described in Patent Document 1, a guide for forming a paper passage and a separation claw are interlocked. Thus, when a jam occurs, the guide is pressed by the jam paper, and the separation claw is moved backward in conjunction with the guide. Further, in the fixing device described in Patent Document 2, a protrusion is formed at the rear portion of the separation claw (downstream in the conveyance direction of the recording material). When a jam occurs, the leading edge of the separation claw is separated from the roller surface by the jam paper pressing the projection.

Also, some conventional fixing devices have a spur that rotates freely in order to prevent the recorded material separated from the roller by the separation claw from touching the rear portion of the separation claw and damaging the formed image. (For example, refer to Patent Document 3). In the fixing device described in this document, a rotatable spur is provided slightly downstream from the tip of the separation claw. In order to reduce the contact area between the outer peripheral portion of the spur and the recording material, the outer peripheral portion of the spur is thin and jagged. The recording material fixed by the fixing device and separated by the separation claw rotates in contact with the spur to advance the spur. Therefore, the area of the member in contact with the recording material immediately after fixing is very small, and the formed image is prevented from being damaged.
JP-A-6-194990 JP-A-7-28352 JP 2001-175112 A

  However, in the fixing device described in Patent Document 1, the configuration for moving the separation claw is quite complicated. Furthermore, the separation claw moves only when the guide is pressed. If jammed paper first accumulates around the separation claw, the separation claw itself may be pressed before the guide is pressed. There is. In that case, there is a problem that the tip of the separation claw may bite into the roller.

  Further, in the fixing device described in Patent Document 2, the protruding portion always protrudes into the sheet passing path. For this reason, there is a possibility that the recording material may come into contact with the protruding portion other than when the jam occurs. When the image surface of the recording material rubs against such a portion, there is a problem in that the image quality is deteriorated.

  Further, in the fixing device described in Patent Document 3, a rotatable spur protrudes into the sheet passing path. Therefore, when a jam occurs, the spur may be pressed by the jam paper. Since the spur is attached to the separation claw, this pressing force is a force in the direction of pressing the separation claw against the roller. As a result, there is a problem that the roller may be damaged.

  The present invention has been made to solve the above-described problems of the prior art. That is, the problem is that when a jam occurs, the tip of the separation claw is separated from the roller, and a separation device, a conveyance device, a fixing device, and an image that maintain both good image quality and prevent roller breakage. It is to provide a forming apparatus.

  The separation device of the present invention, which has been made for the purpose of solving this problem, is located downstream of the contact position of the first rotating body and the second rotating body that conveys the sheet-shaped member through the sheet-shaped member to the contact position. A separation device for separating the sheet-shaped member from the first rotating body, which is provided at a position between the passage path of the sheet-shaped member and the first rotating body, and is rotatable about an axis and has a rotating shaft. A separation member that comes into contact with the surface of the first rotating body at the tip upstream of the sheet-like member in the traveling direction, and a pressed member that protrudes from the surface of the separation member on the sheet-like member side. The member is located on the downstream side in the traveling direction of the sheet-like member with respect to the rotating shaft of the separating member.

  According to the separation device of the present invention, the sheet-like member is conveyed by being passed through the contact portion of the first rotating body and the second rotating body. Further, it is separated from the first rotating body by the separation device downstream of the contact point. At this time, the separation device includes a separation member and a pressed member provided to protrude. From this, when the jam of the sheet-like member occurs in the vicinity of the separation device, the pressed member is pressed toward the first rotating body by the sheet-like member. Here, since the pressed member is located on the downstream side in the traveling direction of the sheet-like member with respect to the rotating shaft of the separating member, the tip on the upstream side of the separating member is pressed away from the first rotating body. Therefore, when a jam occurs, the tip of the separation claw is separated from the roller, so that the roller is prevented from being broken.

Furthermore, in the present invention, the pressed member is a separation rotating body rotatably provided on the separation member, and the rotation shaft of the separation rotation body is located downstream of the rotation axis of the separation member in the traveling direction of the sheet-like member. It is desirable.
If it does in this way, after a sheet-like member will be separated from the 1st rotating body by a separating member, it will contact and contact a separating rotating body. Since the separation rotator is rotatable, it rotates following the progress of the sheet-like member, and the surface of the sheet-like member is not rubbed, so that good image quality is maintained. Further, when the separation rotator is pressed by jammed paper or the like, the rotation shaft position of the separation rotator is pressed against the separation member. Since the rotation shaft of the separation rotating body is located downstream of the rotation shaft of the separation member in the traveling direction of the sheet-like member, the pressing force by the jammed paper is in the direction in which the tip of the separation member is separated from the first rotation body. Therefore, when a jam occurs, the tip of the separation claw is separated from the roller, so that the separation device achieves both good image quality and prevention of roller breakage.

Furthermore, in the present invention, it is desirable to have a rotation restricting member that restricts rotation of the separating member in a direction in which the tip of the separating member is separated from the first rotating body.
If the separating member is too far away from the first rotating body, there is a risk of contact with the second rotating body. If it does in this way, it can control with a smaller rotation angle in which a separation member contacts the 2nd rotating body.

Furthermore, in the present invention, it is desirable that the maximum distance between the tip of the separation member regulated by the rotation regulating member and the first rotating body is within 0.5 mm.
In this way, there is no possibility that a part of the sheet-like member enters between the tip of the separation member and the first rotating body.

Furthermore, in the present invention, it is desirable to have a biasing member that biases the separation member in a direction in which the tip of the separation member is pressed against the first rotating body.
In this way, when the pressed member is not pressed, the separating member is in contact with the first rotating body by the biasing member. Therefore, separation by the separation member can be performed.

  Further, the present invention includes a first rotating body and a second rotating body, the surface of the first rotating body and the surface of the second rotating body are in contact with each other, and a sheet-like member is passed through the contact portion through the sheet-like member. A transport device that transports a member, and is located downstream of the contact point between the first rotating body and the second rotating body in the traveling direction of the sheet-shaped member and between the passage of the sheet-shaped member and the first rotating body. Provided with a separating device for separating the sheet-like member from the first rotating body, the separating device being rotatable about an axis and having a first end upstream of the rotating shaft in the traveling direction of the sheet-like member. A separating member that contacts the surface of the rotating body; and a pressed member that protrudes from the surface of the separating member on the sheet-like member side, and the pressed member advances from the rotating shaft of the separating member. It extends to a transport device located downstream in the direction.

  The present invention also includes a heating rotator and a pressure rotator, and the surface of the heating rotator and the surface of the pressure rotator are in contact with each other. A fixing device for fixing a toner image of the recording medium, wherein the recording material is downstream of the contact point between the heating rotator and the pressure rotator in the traveling direction of the recording material and between the passage of the recording material and the heating rotator. Provided with a separation device for separating the recording material from the heating rotator, the separation device being rotatable about the axis, and being heated at the tip upstream of the recording material in the advancing direction of the recording material. A separating member that contacts the surface of the recording member and a pressed member that protrudes from the surface of the separating member on the recording material side, and the pressed member is downstream of the rotating shaft of the separating member in the traveling direction of the recording material. It extends to the fixing device located on the side.

  The present invention also includes an image forming unit that forms a toner image on a recording material with toner, a heating rotator, and a pressure rotator, and includes a surface of the heating rotator and a surface of the pressure rotator. Is an image forming apparatus for forming an image by fixing a toner image on a recording material through a recording material on which a toner image has been formed at the contact portion, the heating rotator and the pressure rotator A separation device for separating the recording material from the heating rotator, which is provided downstream of the contact point with the recording material in the traveling direction of the recording material and between the passage of the recording material and the heating rotator, The separation device is rotatable about an axis, and is separated from the surface of the recording material side of the separation member, the separation member contacting the surface of the heating rotator at the tip upstream of the recording material in the traveling direction of the recording material. The pressed member is provided with a separating portion. Also extends to an image forming apparatus located in the traveling direction downstream side of the recording material from the rotary shaft.

  According to the separation device, the conveyance device, the fixing device, and the image forming device of the present invention, when a jam occurs, the tip of the separation claw is separated from the roller, and both good image quality maintenance and prevention of roller breakage are achieved. is doing.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a tandem color printer.

  As schematically shown in FIG. 1, the color printer 1 of this embodiment includes yellow (Y), magenta (M), cyan (C), and black (K) process units 10Y, 10M, 10C, and 10K. A so-called tandem type is arranged along the intermediate transfer belt 11. Each of the process units 10Y, 10M, 10C, and 10K is a general unit for image formation, and includes a photosensitive drum, a charging device, an exposure device, a developing device, a cleaning device, and the like. The color printer 1 further includes a paper feed cassette 12, a secondary transfer roller 13, a fixing unit 14, a paper discharge tray 15, and the like. In the following text, YMCK subscripts are omitted when there is no need to distinguish between them.

  As shown in FIG. 2, the fixing unit 14 of this embodiment includes a heating roller 21 and a pressure roller 22 that are two rollers having substantially the same outer diameter. The heating roller 21 has a heater 23 at the center, and the entire roller is heated by this. Further, an elastic body layer 24 is formed on the outer peripheral surface, and an aluminum cored bar 25 is provided on the inner peripheral side thereof. Further, a fluorine tube layer may be provided on the outer surface of the elastic body layer 24. On the other hand, the pressure roller 22 has an elastic layer 26 on the outer peripheral surface and a core metal 27 on the inner peripheral side thereof. The material of the elastic layers 24 and 26 is silicon rubber or the like.

  Here, as shown in FIG. 2, the elastic layer 24 of the heating roller 21 is formed relatively thin. This is to make the preheating time of the heating roller 21 as short as possible. On the other hand, the elastic body layer 26 of the pressure roller 22 is formed relatively thick. This is to obtain a nip necessary for fixing even if the elastic layer 24 is thin. When the recording paper 28 passes through the nip between these rollers 21 and 22, the recording paper 28 is simultaneously subjected to heating and pressurization. As a result, the toner is fixed. Further, on the downstream side of the nip of these rollers, a separation device 30 is provided in contact with the surface of the heating roller 21.

  As shown in FIGS. 2 and 3, the separation device 30 includes a separation claw 31 and a spur 32. As shown in FIG. 4, the separation claw 31 is a member having a thin tip portion (lower end portion in the figure), and has a rotating shaft 33 at a position slightly below the central portion and projecting to the left side in the figure. Yes. As shown in FIGS. 2 and 3, the spur 32 has a jagged periphery and is rotatably attached to the separation claw 31 by a rotary shaft 34. That is, the spur 32 is rotated integrally with the separation claw 31 by the rotation shaft 33 and is rotated alone by the rotation shaft 34. The rotation shaft 33 of the separation claw 31 is arranged in the lower left of the drawing (position closer to the heating roller 21) compared to the rotation shaft 34 of the spur 32.

  Further, as shown in FIGS. 3 and 4, the separation claw 31 has one end of a spring 35 fixed to the upper part in the drawing. The other end of the spring 35 is fixed to a predetermined location inside the color printer 1. The upper portion of the separation claw 31 is biased rightward in the drawing by the spring 35 so that the tip end portion of the separation claw 31 contacts the heating roller 21 with an appropriate pressure. Further, as shown in FIG. 3, the limiting member 36 is provided at a position substantially coaxial with the spring 35. When the separation claw 31 is rotated counterclockwise around the rotation shaft 33 in the figure, the upper portion of the separation claw 31 abuts against the restriction member 36 to restrict further rotation.

  Further, in the color printer 1, as shown in FIG. 3, a slightly curved sheet passing path 41 is provided from the right side to the upper side of the separation device 30 in the drawing. The recording paper 28 that has been fixed by the fixing unit 14 is discharged through the paper passing path 41. A sensor 42 for detecting the recording paper 28 passing through the paper passing path 41 is provided above the separation device 30 in the drawing.

  Next, the operation of the color printer 1 will be described. When the printing operation is started, first, a toner image of each color is formed on the photosensitive drum of each process unit 10 based on image data instructed to form an image. The formed toner images of the respective colors are superimposed on the intermediate transfer belt 11 and transferred by the secondary transfer roller 13 onto the recording paper 28 conveyed from the paper feed cassette 12. As shown in FIG. 2, the recording paper 28 to which the toner image has been transferred enters the fixing unit 14 from below in the drawing. The recording paper 28 is heated and pressed at the nip between the heating roller 21 and the pressure roller 22 to fix the toner image.

  The recording paper 28 that has passed through the nip between the heating roller 21 and the pressure roller 22 generally sticks to the surface of the heating roller 21 and is separated from the heating roller 21 by the separating device 30. That is, first, the leading end of the recording paper 28 comes into contact with the leading end of the separation claw 31 and moves away from the heating roller 21 along the separation claw 31. Next, the leading end portion of the recording paper 28 passes through the right side in FIG. 3 of the separating device 30 and advances while contacting the outer peripheral portion of the spur 32. At this time, the outer peripheral portion of the spur 32 has a jagged shape, a small contact area with the recording paper 28, and is rotatable, so that the spur 32 is rotated following the progress of the recording paper 28. Therefore, since the image surface is not rubbed, good image quality is maintained. Then, the recording paper 28 advances in the direction of the white arrow in FIG. 3 along the paper passing path 41 and is discharged to the paper discharge tray 15 after being detected by the sensor 42.

  However, the recording paper 28 may not travel along this route as scheduled. If the sensor 42 does not detect within a predetermined time after starting the fixing operation, the fixing operation is immediately stopped. This may be due to a paper jam at the entrance of the fixing unit 14 or a separation failure in the separation device 30. On the other hand, after the leading end of the recording paper 28 is detected by the sensor 42, a jam may occur in the middle of the paper passing path 41 as shown in FIG. A part of the recording paper 28 hits the wall surface of the paper passing path 41 and stops. In this case, since the fixing unit 14 is not stopped immediately, the recording paper 28 is stagnated in the paper passing path 41 as shown in FIG. The separating device 30 receives a pressing force in the left direction in the figure by the staying recording paper 28.

  Here, since the spur 32 is the most arranged in the right side of the drawing in the separating device 30, the recording paper 28 first presses the spur 32 to the left. Since the spur 32 is attached to the separation claw 31 by the rotation shaft 34, the pressing force by the recording paper 28 is a pressing force for pushing the position of the rotation shaft 34 of the separation claw 31 leftward in the drawing as shown in FIG. p. At this time, since the rotation shaft 34 is above the rotation shaft 33 in the figure, the separation claw 31 receives a counterclockwise rotation force in the figure about the rotation shaft 33. Then, until the upper portion of the separation claw 31 comes into contact with the restricting member 36, it is rotated overcoming the biasing force q of the spring 35. As a result, as shown by a dotted line in FIG. 4, the tip of the separation claw 31 moves to the right by the distance r. This is the arrangement shown in FIG.

  That is, when the recording paper 28 is jammed in the paper passing path 41, the leading end of the separation claw 31 is separated from the heating roller 21 by the pressing force p of the recording paper 28. Therefore, the leading end of the separation claw 31 is not pressed against the heating roller 21 due to the occurrence of a jam, and there is no possibility of damaging the elastic member 24 of the heating roller 21. The separated distance r is defined to be 0.5 mm or less depending on the arrangement of the limiting member 36. If the distance r is too large, a part of the recording paper 28 may enter between the heating roller 21 and the separation claw 31, which is not preferable.

  As described above in detail, according to the color printer 1 of the present embodiment, the fixing unit 14 includes the separating device 30, so that the recording paper 28 after fixing is easily separated from the heating roller 21. Here, since the separating device 30 has a rotatable spur 32, the image surface is not rubbed and good image quality is maintained. Furthermore, since the rotation shaft 33 of the separation claw 31 is provided at a position closer to the heating roller 21 than the rotation shaft 34 of the spur 32, when the spur 32 is pressed toward the heating roller 21, the separation claw 31 is separated. The tip of the claw 31 is rotated in a direction away from the heating roller 21. Therefore, when a jam occurs on the exit side of the fixing unit 14, the tip of the separation claw 31 is separated from the heating roller 21. As a result, when a jam occurs, the tip of the separation claw 31 is separated from the heating roller 21, so that the fixing unit 14 is compatible with both maintaining good image quality and preventing the heating roller 21 from being destroyed.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, in the above embodiment, the limiting member 36 is provided coaxially with the spring 35 so as to contact the upper portion of the separation claw 31. However, the arrangement of the limiting member 36 is not limited to this, and it is sufficient that the maximum rotation angle of the separation claw 31 is limited. For example, it can be limited by the shortest compression width of the spring 35.
Further, for example, in the above embodiment, the color printer 1 using the fixing unit 14 using the heating roller 21 is illustrated, but a heating roller having a belt-like elastic layer may be used. The material of the elastic body layer and the metal core is not limited to the above.
Further, for example, the present invention is applicable not only to the color printer 1 but also to an image forming apparatus such as a monochrome printer, a facsimile machine, and a copier. Further, the present invention is not limited to the fixing device, and can be applied to a paper or document conveying device and a separating device.

1 is a schematic configuration diagram of a main part of a color printer according to an embodiment. 1 is a schematic configuration diagram of a fixing device. It is explanatory drawing which shows schematic structure of a separation apparatus. It is explanatory drawing which shows a motion of a separation nail. It is explanatory drawing which shows the motion of a separation apparatus.

Explanation of symbols

1 Color printer (image forming device)
10Y, 10M, 10C, 10K process unit (image forming unit)
14 Fixing unit (conveying device, fixing device)
21 Heating roller (first rotating body, heating rotating body)
22 Pressure roller (second rotary body, pressure rotary body)
30 Separation device 31 Separation claw (separation member)
32 Spur (pressed member, separated rotating body)
35 Spring (biasing member)
36 Restriction member (rotation restriction member)

Claims (7)

The sheet-like member is transported through the sheet-like member to the contact location, and the downstream of the sheet-like member in the traveling direction from the contact location of the first rotating body and the second rotary body, and between the passage path of the sheet-like member and the first rotary body In the separating apparatus for separating the sheet-like member from the first rotating body,
A separation member that is rotatable about an axis and is in contact with the surface of the first rotating body at a tip upstream of the rotation axis in the traveling direction of the sheet-like member;
A pressed member provided so as to protrude from the surface on the sheet-like member side of the separating member;
The separation device according to claim 1, wherein the pressed member is located downstream of the rotation axis of the separation member in the traveling direction of the sheet-like member. The separation device according to claim 1,
The pressed member is a separation rotating body provided rotatably on the separation member,
The separation apparatus according to claim 1, wherein a rotation shaft of the separation rotating body is located downstream of the rotation shaft of the separation member in the traveling direction of the sheet-like member. The separation device according to claim 1,
A separation device comprising: a rotation regulating member that regulates rotation of the separation member in a direction in which a tip of the separation member is separated from the first rotating body. The separation device according to claim 1,
A separation device comprising a biasing member that biases the separation member in a direction in which the tip of the separation member is pressed against the first rotating body. A first rotating body and a second rotating body are provided, the surface of the first rotating body and the surface of the second rotating body are in contact with each other, and the sheet-like member is conveyed through the sheet-like member to the contact location. In the transport device,
The first rotating body and the second rotating body are provided at a position downstream of the contact portion between the first rotating body and the second rotating body in the traveling direction of the sheet-like member and between the passage of the sheet-like member and the first rotating body A separation device for separating the sheet-like member from the rotating body;
The separator is
A separation member that is rotatable about an axis and is in contact with the surface of the first rotating body at a tip on the upstream side in the traveling direction of the sheet-like member from the rotation shaft;
A pressed member provided so as to protrude from the surface on the sheet-like member side of the separating member;
The conveying device, wherein the pressed member is located downstream of the rotation axis of the separating member in the traveling direction of the sheet-like member. A heating rotator and a pressure rotator, wherein the surface of the heating rotator and the surface of the pressure rotator are in contact with each other, and a toner image on the recording material is passed through the recording material at the contact point. In the fixing device for fixing,
Provided downstream of the contact position between the heating rotator and the pressure rotator in the traveling direction of the recording material and between the passage of the recording material and the heating rotator, A separation device for separating the recording material;
The separator is
A separation member that is rotatable about an axis and is in contact with the surface of the heating rotator at the tip upstream of the recording material in the traveling direction of the recording material;
A pressed member provided so as to protrude from the surface on the recording material side of the separating member;
The fixing device is characterized in that the pressed member is located downstream of the rotating shaft of the separating member in the traveling direction of the recording material. An image forming unit that forms a toner image on a recording material with toner, a heating rotator, and a pressure rotator, and the surface of the heating rotator and the surface of the pressure rotator are in contact with each other. In the image forming apparatus for forming an image by fixing the toner image on the recording material through the recording material on which the toner image has been formed at the contact location,
Provided downstream of the contact position between the heating rotator and the pressure rotator in the traveling direction of the recording material and between the passage of the recording material and the heating rotator, A separation device for separating the recording material;
The separator is
A separation member that is rotatable about an axis and is in contact with the surface of the heating rotator at the tip upstream of the recording material in the traveling direction of the recording material;
A pressed member provided so as to protrude from the surface on the recording material side of the separating member;
The image forming apparatus according to claim 1, wherein the pressed member is located downstream of the rotation axis of the separation member in the traveling direction of the recording material.

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