JP4483575B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device used in an electrophotographic image forming apparatus, and more particularly to a technique for separating a recording material after fixing from a heating member.

  In an electrophotographic image forming apparatus, generally, a recording material carrying an unfixed toner image is passed between a heating member and a pressure member that are pressed against each other, whereby the toner image is fixed to the recording material by heat and pressure. In general, such a fixing device has a separation claw for separating the recording material after fixing from the heating member.

  Thus, the leading end of the separation claw contacts the heating member to guide the recording material to separate the recording material. However, when a jam occurs in the fixing device, the leading end of the separation claw is separated from the heating member. There is a need. If the leading edge of the separation claw remains in contact when a jam occurs, the leading edge of the separation claw is strongly pressed against the heating member by the jammed recording material, or when the jammed recording material is removed, The tip of the separation claw is strongly pressed against the heating member. As a result, the separation claw damages the surface of the heating member, and the heating member needs to be replaced.

Mechanism to separate the tip of the separation claw when the jam of the recording material occurs from the heating member is not easy because the narrow separation claw is installation space, with respect to the mechanism that has various contrivances have been made conventionally.

  In Patent Document 1, the tip of the separation claw is received by a U-shaped receiving portion so that the tip of the separation claw can be moved between the contact position and the separation position, and the receiving portion is biased by a biasing member. A fixing device is disclosed in which is brought into contact with the surface of a heating member.

  In Patent Document 2, when the tip is at a retracted position away from the rotating body, a strong force is applied to the separation claw so that the tip does not come into contact with the rotating body. A guide member having a guide surface that forms the same surface is provided.

In Patent Literature 3, when the tip is at a retracted position away from the rotating body, a force is applied to the separation claw so that the movement of the separation claw is restricted in order to prevent the tip from contacting the rotating body. A fixing device provided with means has been proposed.
JP 2001-240284 A JP 2003-255749 A JP 2003-255750 A

  Since the mechanism of Patent Document 1 moves the separation claw only in one direction and retracts it, the separation claw of the separation claw is secured in order to retreat to a position where contact with the heating member can be reliably prevented. There is a problem that the installation space becomes large and the fixing device becomes large.

  In Patent Documents 2 and 3, since the number of components is increased and the structure is complicated, there is a problem that the assembly process is complicated and the cost is increased. In Patent Documents 2 and 3, since many parts are installed in a narrow space, it is not easy to remove the jammed recording material, and the operability for releasing jamming is not good.

  The present invention provides a fixing device that has a simple structure and that reliably prevents the tip of the separation claw from coming into contact with the heating member even when forces having different strengths are applied to the separation claw during jamming and jam release. The purpose is to provide.

The object is achieved by the following invention.
(Claim 1)
A heating member that heats the toner image, a pressure member that presses against the heating member, a separation claw that contacts the heating member, a support member that supports the separation claw , and a separation claw that supports the separation claw at the heating member The toner image is fixed to the recording material by heat and pressure through a recording material carrying an unfixed toner image between the heating member and the pressure member. In the fixing device for separating the recording material from the heating member by the separation claw,
A first pin member provided on the separation claw and functioning as a first fulcrum;
A second pin member provided on the separation claw and functioning as a second fulcrum;
A first guide portion provided on the support member for receiving and guiding the first pin member ; and
A second guide portion provided on the support member for receiving and guiding the second pin member ;
The first guide portion includes a first receiving portion that rotatably receives the first pin member, a linear portion that guides the first pin member to the side opposite to the conveyance path of the recording material, and the first pin member Consisting of a second receiving part larger than the outer diameter,
The second guide part is positioned closer to the recording material conveyance path than the first guide part, and the inclined second pin member guide part guides the second pin member in a direction away from the heating member and the conveyance path. A second pin member receiving portion provided at an end of the second pin member guide portion and rotatably receiving the second pin member;
In a normal state in which the recording material is separated, the separation claw is rotatable about the first pin member received by the first receiving portion , and a tip thereof contacts the heating member,
When a force is applied to the separation claw , the separation claw rotates around the first pin member, and the first pin member is guided by the linear portion to the second receiving portion side. move, and the first movement and the second pin member is moved to the portion receiving the second pin member is guided by the second pin member guide unit, the tip of that is separated from the heating member,
When further force to said separation claw is applied, the separating claw is rotated around the second pin member in a state in which the second pin member enters the second pin member receiving portion, said first the second movement 1 pin member is moved to the heating member side of the second receiving unit, a fixing device that the tip is equal to or further away from the heating element.
(Claim 2)
The fixing device according to claim 1, wherein the heating member includes a heat-resistant elastic layer.

  According to the first or second aspect of the present invention, the separation claw is reliably separated from the surface of the heating member when the jam occurs and when the jammed recording material is removed by the simple support structure in which the separation claw is supported by the support member. Therefore, damage to the heating member can be prevented with a simple structure.

  Therefore, an assembling is simple and a low-cost fixing device is realized. In addition, since the structure of the recording material guide portion on which the separation claw is arranged is simple, it is easy to remove the jammed recording material, and a fixing device with good operability for jam release is realized.

  According to the second aspect of the present invention, even when a so-called soft roller is used for the heating member, the surface of the heating member is reliably prevented from being damaged when a jam occurs.

  Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited to the embodiments. FIG. 1 is a sectional view of a fixing device according to an embodiment of the present invention.

  Each component constituting the fixing device is arranged in a bowl-shaped frame A. Reference numerals 1 and 2 are guide plates for guiding the entry of the recording material P. Reference numeral 3 denotes a heating roller as a heating member that heats the recording material P and fixes the toner image, and includes a cored bar 3a, a heat resistant elastic layer 3b, and a releasable surface layer 3c. As the heating roller 3, a so-called hard roller in which a releasable surface layer is provided on a core metal or a so-called soft roller in which a heat-resistant elastic layer and a releasable surface layer are provided thereon is used. However, a soft roller is preferably used for fixing a toner image having a large amount of toner such as a color image.

4 is a pressure roller as a pressure member for pressing the recording material P to the heating roller 3, similar to the heating roller 3, the metal core, and a heat-resistant elastic layer and a releasing surface layer. A belt can also be used as the heating member 3 and the pressure member 4. A heater 5 provided in the heating roller 3 heats the heating roller 3. Although a halogen lamp is used as the heater 5, a heater such as a resistance heating element or an induction heating element can be used. Reference numeral 6 denotes a cleaning web for cleaning the surface of the heating roller 3. Reference numerals 7 and 8 are guide members for guiding the discharge of the recording material.

  Reference numeral 10 denotes a separation claw for separating the recording material P from the heating roller 3, and 9 is a separation claw for separating the recording material P from the pressure roller 4.

  When the heating roller 3 is driven by a motor (not shown), the heating roller 3 and the pressure roller 4 are rotated as indicated by arrows, respectively, and the recording material P is conveyed as indicated by arrows, and the recording material P is heated by the heating roller. The toner image T on the recording material P is fixed by passing through the nip between the pressure roller 3 and the pressure roller 4.

  FIG. 2 is a view showing the support structure and operation of the separation claw 10 for separating the recording material from the heating roller 3.

The separation claw 10 includes a tip portion 10a that contacts the heating roller 3, a guide portion 10b that guides the recording material, a pin 10c that constitutes a first fulcrum (first pin member), and a pin 10d that constitutes a second fulcrum (second pin). It is made of an inverted L-shaped resin molded member having a member.

  The support member 11 that is a part of the frame A and supports the separation claw 10 is made of a plate material, and the hole 12 that forms the first guide portion at the upper portion and the guide that forms the second guide portion at the lower end portion. Each edge 13 is formed.

FIG. 3 is an enlarged view of the hole 12. The hole 12 has a hole portion 12a (first receiving portion) having a diameter slightly larger than the outer diameter of the pin 10c, and a hole portion 12b having a diameter considerably larger than the outer diameter of the pin 10c. (2nd receiving part) It consists of the linear part 12c which connects the hole part 12a and the hole part 12b. The pin 10c is fitted in a state where slight play is interposed in the hole 12a.

FIG. 4 is an enlarged view of the guide edge 13, and the guide edge 13 includes a guide portion 13a (second pin member guide portion) and a receiving portion 13b (second pin member receiving portion) that are inclined upward to the right. The receiving portion 13b is formed of a semicircular arc having a diameter slightly larger than the outer diameter of the pin 10d. The pin 10d is inserted in a state where a slight play is interposed in the receiving portion 13b.

  Reference numeral 14 denotes a spring having an upper end attached to the separation claw 10 and a lower end attached to the support member 11 and biasing the separation claw 10 downward.

2A shows a normal state in which the leading end 10a contacts the heating roller 3 to separate and guide the recording material, and FIG. 2B shows the recording material jammed due to the jamming of the recording material. 2 (a) shows a state where a force F1 as indicated by an arrow is applied to the separation claw 10 , and FIG. 2 (c) shows a state where a larger force F2 is applied to the separation claw 10.

  In the normal state, that is, the state shown in FIG. 2A, the pin 10 c is fitted into the hole 12 a by the urging force of the spring 14, and the separation claw 10 can rotate about the pin 10 c as a fulcrum. The tip 10 a is biased in the clockwise direction and is in contact with the heating roller 3.

  When a jam occurs and the recording material is jammed between the guide member 7 and the guide member 8 in an accordion shape, a force F1 that pushes the separation claw 10 upward is applied. The separation claw 10 rises from the state of FIG. 2A by the action of the force F1 (first movement). When the first movement rises, the separation claw 10 is guided by the guide portion 13a, and the pin 10d rises along the guide portion 13a, resulting in the state shown in FIG. In the state of FIG. 2B, the pin 10 c is in contact with the linear portion 12 c by the action of the spring 14.

  As shown in FIG. 2 (b), when the separation claw 10 moves upward, the pin 10c rises vertically while the pin 10d rises diagonally to the right. Is rotated counterclockwise and the tip 10 a is separated from the surface of the heating roller 3.

  When a force F2 for pushing the separation claw 10 further upward is applied by the clogged recording material or when removing the clogged recording material, the separation claw 10 is changed from the state of FIG. 2B to FIG. 2C. (Second movement).

  That is, the second movement is performed in which the pin 10 (c) moves to the upper left along the edge of the hole 12b. During the second movement, since the pin 10d is fitted in the receiving portion 13b, the separation claw 10 rotates counterclockwise about the pin 10d. Accordingly, the distal end portion 10a further moves rightward from the position shown in FIG. 2B and moves to the position shown in FIG. 2C away from the surface of the heating roller 3.

  As described above, the tip 10a of the separation claw 10 is normally in contact with the surface of the heating roller 3, but when a jam occurs, it is separated from the surface of the heating roller 3 by the pushing force F1 of the jammed recording material ( (First movement), further away when the push-up force F2 is applied (second movement), it is reliably prevented that the heating roller 3 is damaged by the separation claw 10 at the time of jam occurrence and jam recovery operation. .

  As shown in FIG. 1, in the soft roller in which the heat-resistant elastic layer 3b is formed on the cored bar 3a and the releasable surface layer 3c is formed thereon, the tip portion 10a of the separation claw 10 is easy to bite, and the heating roller 3 is easily damaged, but the separation claw 10 is retracted by the first movement and the second movement as described above, so that the heating roller 3 is reliably prevented from being damaged.

  And since it is a structure which only provides the support member 11 which supports the separation nail | claw 10, the support structure of the separation nail | claw 10 with the retraction | saving mechanism which operate | moves very simply and reliably is implement | achieved.

1 is a cross-sectional view of a fixing device according to an embodiment of the present invention. It is a figure which shows the support structure and operation | movement of a separation nail. It is an enlarged view of a hole. It is an enlarged view of a guide edge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Heating roller 4 Pressure roller 10 Separation claw 10a Tip part 10c, 10d Pin 11 Support member 12 Hole 13 Guide edge

Claims (2)

A heating member that heats the toner image, a pressure member that presses against the heating member, a separation claw that contacts the heating member, a support member that supports the separation claw , and a separation claw that supports the separation claw at the heating member The toner image is fixed to the recording material by heat and pressure through a recording material carrying an unfixed toner image between the heating member and the pressure member. In the fixing device for separating the recording material from the heating member by the separation claw,
A first pin member provided on the separation claw and functioning as a first fulcrum;
A second pin member provided on the separation claw and functioning as a second fulcrum;
A first guide portion provided on the support member for receiving and guiding the first pin member ; and
A second guide portion provided on the support member for receiving and guiding the second pin member ;
The first guide portion includes a first receiving portion that rotatably receives the first pin member, a linear portion that guides the first pin member to the side opposite to the conveyance path of the recording material, and the first pin member Consisting of a second receiving part larger than the outer diameter,
The second guide part is positioned closer to the recording material conveyance path than the first guide part, and the inclined second pin member guide part guides the second pin member in a direction away from the heating member and the conveyance path. A second pin member receiving portion provided at an end of the second pin member guide portion and rotatably receiving the second pin member;
In a normal state in which the recording material is separated, the separation claw is rotatable about the first pin member received by the first receiving portion , and a tip thereof contacts the heating member,
When a force is applied to the separation claw , the separation claw rotates around the first pin member, and the first pin member is guided by the linear portion to the second receiving portion side. move, and the first movement and the second pin member is moved to the portion receiving the second pin member is guided by the second pin member guide unit, the tip of that is separated from the heating member,
When further force to said separation claw is applied, the separating claw is rotated around the second pin member in a state in which the second pin member enters the second pin member receiving portion, said first the second movement 1 pin member is moved to the heating member side of the second receiving unit, a fixing device that the tip is equal to or further away from the heating element. The fixing device according to claim 1, wherein the heating member includes a heat-resistant elastic layer.

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