JP2011007977A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt nip type fixing device of good maintenance work efficiency.SOLUTION: The fixing device is constituted in such a manner that one of rollers constituting a fixing belt unit is supported to be movable relative to a frame body of a fixing roller unit, and tension of a fixing belt is automatically released when the fixing belt unit is detached from the fixing device. When the fixing belt unit is attached to the fixing device, the frame body of the fixing belt unit and the movable roller are each engaged with and positioned with respect to the fixing device, then tension is given to the fixing belt. Thus, the fixing belt unit is energized to the fixing device by belt tension acting on the fixing belt unit and is prevented from falling off as a result.

Description

  The present invention relates to a fixing device used in a printer, a copying machine, a facsimile, or the like that employs an electrophotographic system or an electrostatic recording system.

  Conventionally, as an electrophotographic fixing device, a belt nip type fixing device in which a fixing nip is widened by using an endless belt has been proposed in Patent Document 1 and the like. This is a method in which a heat-fixing roller rotatably supported and a pressure belt capable of endless movement are pressed against each other, and a recording sheet is fed and fixed between them, which is called a belt nip method or the like. .

  FIG. 7 shows a conventional belt nip type fixing device. A fixing roller 510, which is a rotating member for fixing arranged rotatably, is rotated in the direction of arrow A by a driving source (not shown) and is heated by a halogen heater 520 arranged therein.

  A belt unit 53 is disposed below the fixing roller 510. The endless fixing belt 531 is stretched around an entrance roller 532, a separation roller 533, and a tension roller 534. The separation roller 533 is made of metal such as SUS and is in pressure contact with the fixing roller 510 via the fixing belt 531 in the direction of arrow SF. The tension roller arm 5341 rotatably supports the tension roller 534 and is attached to the front plate 544 so as to be slidable in the direction of arrow A. The tension roller 534 is urged to the inner surface of the fixing belt 531 by the tension spring 5342 via the tension roller arm 5341 and applies tension to the fixing belt 531. Further, the tension roller 534 is movable in the arrow B direction with respect to the tension roller arm 5341. The displacement of the fixing belt is controlled by displacing the front end portion and the rear end portion of the tension row 534 in opposite directions by a displacement control means (not shown).

  A pressure pad portion 540 is disposed between the entrance roller 532 and the separation roller 533. The pressure pad unit 540 includes a base 541 made of a metal such as SUS, a pressure pad 542 made of silicon rubber, and a sliding sheet 543 made of a PI film or the like disposed between the pressure pad 542 and the fixing belt 531. And is in pressure contact with the fixing roller 510 via the fixing belt 531 in the direction of the arrow PF.

  Further, an oil application roller 536 is provided between the entrance roller 532 and the pressure pad portion 540. The oil application roller 536 is impregnated with silicon oil, and oil is applied to the inner surface of the fixing belt 531 to reduce the frictional force between the fixing belt 531 and the sliding sheet 543.

  In such a fixing belt 531, a nip W is formed by the fixing roller 510, the fixing belt 531, the pressure pad unit 540, and the separation roller 533. As described above, since the nip width can be widened, the toner on the recording paper can be melted more, and the configuration is suitable for the image forming apparatus using a large amount of toner in the color image forming apparatus.

  By the way, in an electrophotographic image forming apparatus in which such a fixing device is used, there are items that require maintenance such as replenishment of consumables such as toner and replacement of parts whose performance deteriorates due to durability. In order to reduce time, improvement of maintenance workability is required. In particular, in maintenance of the fixing device, it is desirable to be able to work easily without waiting for the high temperature unit to cool down in order to reduce downtime.

JP 2005-292713 A

  The prior art has the following problems. That is, in the case of the fixing device according to Patent Document 1, among the components of the fixing belt unit, the components such as the fixing belt, the pressure pad, the pad cover, and the oil application roller deteriorate performance due to durability. It needs to be replaced. In order to replace these parts, it is necessary to remove the fixing belt unit from the fixing device, release the tension applied to the fixing belt, and remove the fixing belt from the fixing belt unit.

  The present invention has been made to solve the above-described problems of the prior art. The object of the present invention is to easily release the tension of the fixing belt when the fixing belt unit is removed from the fixing device. It is another object of the present invention to provide a fixing device excellent in maintenance workability in which the fixing belt unit can be maintained, and the fixing belt unit can be easily attached to the fixing device.

  The present invention is a fixing device having the following configuration.

  (1) A heat fixing member having a heating source and rotatably arranged, a fixing belt unit in which an endless belt-like belt fixing member is stretched on a plurality of rotating bodies, and the fixing belt unit mounted thereon And a fixing device including a mounting member that pressurizes the heat fixing member, wherein one of the plurality of rotating bodies constituting the fixing belt unit is a tension that applies tension to the belt fixing member. And another one of the plurality of rotating members constituting the fixing belt unit is a moving roller attached to the frame of the fixing belt unit so as to be movable in the diameter direction of the rotating member. The mounting member includes first and second engaging portions for engaging and positioning with the fixing belt unit, and the first engaging portion is a bearing that rotatably supports the moving roller. Element Engaging said second engagement portion constitutes a frame of the fixing belt unit, engages the non-movable member.

  (2) The fixing belt unit is placed on the mounting member, and when the frame body of the fixing belt unit and the moving roller are positioned, tension is applied to the belt fixing member by the tension roller, When the positioning roller is detached from the mounting member and is in a state in which the positioning roller is freely movable with respect to the frame of the fixing belt unit, no tension is applied to the belt fixing member.

  That is, when the fixing belt unit is removed from the fixing device, the tension of the fixing belt is automatically released.

  (3) When the fixing belt unit is placed on the mounting member, the force acting on the frame of the belt fixing member due to the tension of the belt fixing member is in a direction to press the belt unit against the mounting member. Works.

  That is, when the fixing belt unit is attached to the fixing device, the tension of the fixing belt acts in the direction of pressing the fixing belt unit against the fixing device, so that a member for fixing the fixing belt unit is unnecessary.

According to the present invention,
When the fixing belt unit is removed from the fixing device, the fixing belt tension is automatically released, and the fixing belt unit can be easily maintained, and the fixing belt unit can be easily attached to the fixing device. Therefore, it is possible to provide a fixing device that is excellent in maintenance workability.

FIG. 3 is a cross-sectional view illustrating a configuration of a fixing device of the present invention. FIG. 3 is a front view showing the configuration of the fixing device of the present invention. FIG. 3 is a view showing a pressure mechanism of a fixing belt unit of the fixing device of the present invention. FIG. 4 is a diagram illustrating a pressing operation of a fixing belt unit of the fixing device of the present invention. FIG. 4 is a diagram illustrating a method for attaching and detaching the fixing belt unit of the fixing device of the present invention. FIG. 3 is a diagram illustrating a mounting state of a fixing belt unit of the fixing device of the present invention. Conventional belt nip type fixing device. FIG. 4 is a diagram illustrating a method for attaching and detaching the fixing belt unit of the fixing device of the present invention. FIG. 4 is a diagram illustrating a method for attaching and detaching the fixing belt unit of the fixing device of the present invention.

Example 1
FIG. 1 is a sectional view of a fixing device showing an embodiment of the present invention. The fixing device 7 includes a fixing roller unit 70 and a fixing belt unit 73.

  The fixing roller 71 is provided with an elastic layer 712 made of silicon rubber on a surface layer of a cored bar 711 made of aluminum or the like, and on the surface layer, a fixing layer made of a PFT tube and a release layer for improving the releasability of toner are provided. Is provided. A heater 721 is disposed in the vicinity of the central portion inside the fixing roller.

  In the fixing belt unit 73, a fixing belt 731 that is an endless belt is stretched around an entrance roller 732, a separation roller 733, and a tension roller 734. Further, a pressure pad portion 740 is disposed inside the belt, and a pad base 741 made of metal such as SUS, a pressure pad 742 made of silicon rubber or the like, and a PI film disposed between the pressure pad 742 and the fixing belt 731. It is comprised from the sliding sheet | seat 743 which consists of these.

  An oil application roller 735 is provided between the entrance roller 732 and the pressure pad portion 740. The oil application roller 735 is impregnated with silicon oil, and oil is applied to the inner surface of the fixing belt 731 to reduce the frictional force between the fixing belt 731 and the sliding sheet 743.

  2 is a front view showing an embodiment of the present invention. FIG. 2A shows a state in which the fixing belt unit 73 is attached to the fixing device 7, and FIG. 2B shows a state in which the fixing belt unit 73 is attached. Shows a state in which is removed from the fixing device 7.

  A front plate 744 is attached to the front end portion of the pad base 741 and constitutes a frame of the fixing belt unit 73. The entrance roller arm 7321 supports the entrance roller 732 rotatably and is attached to the front side plate 744 so as to be slidable in the arrow C direction. The tension roller arm 7341 rotatably supports the tension roller 734 and is attached to the front side plate 744 so as to be slidable in the arrow D direction. The tension roller 734 is urged toward the inner surface of the belt by a tension spring 7342 via a tension roller arm 7341 and applies tension to the fixing belt 731. Further, the tension roller 734 is movable in the arrow E direction with respect to the tension roller arm 7341. The displacement of the fixing belt 731 is controlled by displacing the front end portion and the rear end portion of the tension roller 734 in opposite directions by a displacement control means (not shown). The separation roller 733 is supported so as to be movable in the direction of arrow F with respect to the front side plate 744, and is pressed against the fixing roller 71 independently by a pressure mechanism described later.

  In a state where the fixing belt unit 73 is removed from the fixing device 7, the entrance roller arm 7321 can freely slide with respect to the front side plate 744. FIG. 2B shows a state where the entrance roller arm 7321 slides and the entrance roller 732 is retracted to the inside of the belt. At this time, the tension roller 734 abuts on the outermost side of the movable range, but since the retracting amount of the entrance roller 732 is large, no tension is applied to the fixing belt 731 and a large extra length is generated. For this reason, the fixing belt unit 73 of this embodiment does not require the work of releasing the belt tension, and the fixing belt 731 can be removed.

  3A and 3B, the pressing mechanism of the fixing belt unit 73 against the fixing roller 71 will be described.

  Pressure mechanisms 75 are provided at both ends of the fixing belt unit 73. Both sides have substantially the same configuration, and only the front side is shown and described in FIGS. 3 (a) and 3 (b).

  A pressure holder 753 is disposed below the roller pressure holder 751 and the pad pressure holder 752 and is configured to be rotatable about a rotation shaft 754.

  A roller pressure spring 757 is disposed between the pressure holder 753 and the roller pressure holder 751, and a guide shaft 755 fixed to the pressure holder 753 passes through the roller pressure spring and is provided in the roller pressure holder 751. It is arranged through the hole.

  A pad pressure spring 758 is disposed between the pressure holder 753 and the pad pressure holder 752, and the guide shaft 756 fixed to the pressure holder 753 passes through the pad pressure spring and passes to the pad pressure holder 752. It is provided and arranged through the hole.

  A receiving portion 759 is provided on the side surface of the pressure holder 753, and a pressure cam 761 is provided on the rotating shaft 760 below the receiving portion 759.

  The pad pressure holder 752 is provided with an engaging portion J7521 and an engaging portion K7522. A bearing 7322 is provided at the end of the fixing entrance roller 732. An engaging portion L7411 is provided at the end of the pad base 741. When the fixing belt unit 73 is attached to the pressure mechanism unit 75, the bearing 7322 and the engagement portion J7521 of the pressure pad holder 752 are engaged, and the engagement portion L7411 of the pad base 741 and the pressure pad holder 752 are engaged. Part K7522 is engaged. As a result, the frame of the fixing belt unit 73 and the entrance roller 732 are positioned with respect to the pressure mechanism unit 75.

  A bearing 7331 is provided at the end of the separation roller 733. The roller pressure holder 751 is provided with a pressure surface 7511. When the fixing belt unit 73 is attached to the pressure mechanism unit 75, the bearing 7331 comes into contact with the pressure surface 7511 and the separation roller 733 is positioned.

  FIG. 4A shows a state where the fixing belt portion 73 is pressed against the fixing roller 71, and FIG. 4B shows a state where the fixing belt portion 73 is retracted from the fixing roller 71.

  In FIG. 4A, when the pressure cam 761 is rotated by a drive system (not shown) around the rotation shaft 760 and the major diameter of the pressure cam 761 is brought into contact with the receiving portion 759, the receiving portion 759 is pushed upward. Then, the pressure holder 753 rotates in the arrow M direction around the rotation shaft 754. As a result, the roller pressure spring 757 causes the roller pressure holder 751 to rotate about the rotation shaft 754 so that the separation roller 731 is pressed against the fixing roller 71 with the applied pressure SF. Similarly, the pad pressure holder 752 is rotated about the rotation shaft 754 by the pad pressure spring 758 so that the fixing pad portion 740 is pressed against the fixing roller 71 with the applied pressure PF.

  In FIG. 4B, when the pressure cam 761 is rotated by a drive system (not shown) around the rotation shaft 760 and the short diameter 761b of the pressure cam 761 is brought into contact with the receiving portion 759, the receiving portion 759 is The pressure holder 753 is rotated downward in the direction of arrow N about the rotation shaft 754. For this reason, the urging force of the roller pressure spring 757 is not applied by the stopper portion of the guide shaft 755, the roller pressure holder 751 rotates about the rotation shaft 754, and the separation roller 731 is separated from the fixing roller 71. .

  Similarly, the urging force of the pad pressure spring 758 is no longer applied by the stopper portion of the guide shaft 756, and the pad pressure holder 752 rotates about the rotation shaft 754 so that the fixing pad portion 740 moves from the fixing roller 71. Separate.

  Next, with reference to FIGS. 5A, 5B, 8C, 8D, 9E, and 9F, a method for attaching and detaching the fixing belt unit 73 to the drive mechanism unit 75 will be described. To do. FIG. 5 is for illustrative purposes. For the pressure mechanism 75, only the pad pressure holder 752 is shown, and for the fixing belt unit 73, the front plate 744 is shown without being shown.

  In a state where the fixing belt unit 73 is removed (FIG. 5A), the tension roller 734 is urged by the tension spring 7342 and is positioned on the outermost side of the movable range, but the inlet roller arm 7321 slides and the inlet roller arm 7321 slides. Since the roller 732 is retracted inward, no tension is applied to the fixing belt 731.

  From this state, the bearing 7321 of the entrance roller 732 is engaged with the engaging portion J7521 of the pad pressure holder 752 (FIG. 5B). In this state, the engagement portion L7411 of the pad base and the engagement portion K7522 of the pressure holder cannot be engaged with each other due to the interference of the tip portions. When the fixing belt unit 73 is pulled in the direction indicated by the arrow P in FIG. 8C, the tension spring 7342 is compressed and the fixing belt unit 73 is displaced in the direction indicated by the arrow P while the position of the entrance roller 732 is maintained. As shown in FIG. 8C, the tip of the engaging portion L7411 can get over the tip of the engaging portion K7522. As shown in FIG. 8D, when the fixing surface of the pad base 741 is brought into contact with the fixing surface of the pad pressure holder 752 and the force for pulling the belt unit 73 is removed, the tension spring 7342 is extended to extend the belt unit frame. The body is pulled to the right by belt tension. Thus, as shown in FIGS. 9E and 9F, the engaging portion J7521 and the engaging portion L7411 come into contact with each other, and the fixing belt unit is positioned.

  As shown in FIG. 6, since the entrance roller 732 is positioned in the pad pressure holder 752, the fixing belt unit frame is attached to the fixing belt unit frame via the separation roller 733 by the belt tension T. A force that biases in the direction is acting. For this reason, the fixing belt unit 73 does not fall off the pad pressure holder 752 without performing any work for fixing the fixing belt unit 73 to the pad pressure holder 752. Even when the fixing belt unit 73 is detached, the engagement between the engaging portion J7521 and the engaging portion L7411 can be released easily by displacing the fixing belt unit 73 toward the separation roller 733 against the belt tension. Can be removed.

DESCRIPTION OF SYMBOLS 7 Fixing apparatus 70 Fixing roller part 73 Fixing belt unit 71 Fixing roller 711 Core metal 712 Elastic layer 721 Heater 731 Fixing belt 732 Entrance roller 7321 Entrance roller arm 7322 Bearing 733 Separation roller 7331 Bearing 734 Tension roller 7341 Tension spring arm 7342 Oil application roller 740 Pressure pad part 741 Pad base 7411 Engagement part L
742 Pressure pad 743 Sliding sheet 744 Front side plate 751 Roller pressure holder 7511 Pressure surface 752 Pad pressure holder 7521 Engagement section J
7522 Engagement part K
753 Pressure holder 754 Rotating shaft 755 Guide shaft 756 Guide shaft 757 Roller pressure spring 758 Pad pressure spring 759 Receiving portion 760 Rotating shaft 761 Pressure cam

Claims (3)

A heat fixing member having a heating source and rotatably disposed;
A fixing belt unit in which an endless belt-shaped belt fixing member is stretched around a plurality of rotating bodies;
A fixing device including a mounting member that mounts the fixing belt unit and pressurizes the heat fixing member;
One of the plurality of rotating bodies constituting the fixing belt unit is a tension roller that applies tension to the belt fixing member,
The other one of the plurality of rotating bodies constituting the fixing belt unit is a moving roller attached to the frame of the fixing belt unit so as to be movable in the diameter direction of the rotating body,
The mounting member includes first and second engaging portions for engaging and positioning with the fixing belt unit,
The first engagement portion engages with a bearing member that rotatably supports the moving roller. The second engagement portion engages with a non-movable member that constitutes a frame of the fixing belt unit. A fixing device characterized by that. The fixing belt unit includes:
When the frame body of the fixing belt unit and the moving roller are positioned on the mounting member, tension is applied to the belt fixing member by the tension roller,
When the positioning roller is in a state in which it can be freely moved with respect to the frame of the fixing belt unit, the belt fixing member is not tensioned.
The fixing device according to claim 1, wherein: When the fixing belt unit is mounted on the mounting member,
The force acting on the frame of the belt fixing member by the tension of the belt fixing member is
The fixing device according to claim 1, wherein the fixing device acts in a direction in which the belt unit is pressed against the mounting member.

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