JP2003255750A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which prevents a rotary body from being damaged even if a separation claw is pressed beyond a specific degree, and an image forming apparatus. <P>SOLUTION: The fixing device in which the separation claw 60 is in contact with a fixing roller 30 so as to be slidable over the roller 30 is provided with a guide pin 61 which, when the separation claw is pushed up, rotates the separation claw 50 around a support shaft 61 in the direction in which the separation claw 50 is separated from the fixing roller 30 against the action of a spring 54. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device having a separating claw and an image forming apparatus.

[0002]

2. Description of the Related Art An image forming apparatus using a toner for forming a visible image is provided with a fixing device for fixing a toner image on a recording sheet such as transfer paper as a permanent image. In such a fixing device, as shown in FIG.
When the recording sheet P carrying the unfixed toner image T is nipped and conveyed by the fixing roller 100 and the pressure roller 101 pressed against the fixing roller 100,
An apparatus that fixes an unfixed toner image on the recording sheet P by the action of heat and pressure is well known. In many fixing devices of this type, a heating unit is provided inside the fixing roller 100, and the sheet is passed through so that the unfixed toner image side contacts the fixing roller 100. Therefore, since the toner is offset on the fixing roller 100, a Teflon (trade name) coating layer is provided on the surface, or a Teflon tube is wound to improve the releasability and reduce the toner offset.

Further, a separating claw 102 is arranged on the fixing roller 100 in order to prevent the sheet from being wound around due to welding of toner or the like. The separating claw 102 is arranged at a position immediately beyond the nip with the pressure roller 101, and therefore the lower surface of the separating claw 102 is also used as a conveying surface for guiding the sheet between the fixing roller and the discharge roller.

However, when such a separating claw 102 is provided, as shown in FIG. 5, the sheet P jammed in the paper discharge portion is bent in a bellows shape, hits near the tip of the separating claw 102, and is separated. In some cases, the claw 102 was pressed in a direction that bites into the fixing roller 100. When such a phenomenon occurs, the separation claw 102 may peel off the Teflon layer, and the fixing roller 100 may have to be replaced.

Therefore, in Japanese Unexamined Patent Application Publication No. 2001-240284, when the jammed paper pushes the tip of the claw, the separation claw displaces the support shaft, which is the center of rotation, in the direction in which the claw does not bite into the claw. It is disclosed to prevent this.

[0006]

However, even in the fixing device in which the separating claw is displaced, if the separating claw is pressed for a certain amount or more, the fixing roller may be damaged at the tip thereof. In particular, in a fixing roller provided with an elastic layer on the surface to improve image quality, compared to a fixing roller provided with a Teflon layer on a core metal, a nail may bite into the elastic layer and damage it even if the pressing force is small. there were.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a fixing device and an image forming apparatus capable of preventing the rotating body from being damaged even if the separating claw is pressed more than a certain amount.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a rotating body and a claw portion capable of sliding contact with the surface of the rotating body are formed, and the rotating body is mounted rotatably around a support shaft. A separation pawl, a first urging means for urging a rotational force centered on the support shaft in the direction in which the pawl portion is slidably contacting the rotating body toward the separation pawl, and the pawl portion is the rotating body. Means for guiding the support shaft so as to be movable between a sliding contact position in sliding contact with the rotating body and a spaced position separated from the rotating body; and a second means for urging an elastic force for holding the supporting shaft in the sliding contact position. In a fixing device having a biasing means, and the separation claw is configured as a conveyance surface on the side opposite to the side of the claw portion facing the rotating body, the separation claw functions as the second biasing means. When the sliding claw is moved from the sliding contact position toward the separated position, the separation claw is moved to the support shaft. It is characterized by having a regulating means for rotating in a direction away from said rotary body against the action of the first biasing means around.

According to the present invention, when the separating means moves the separating claw from the sliding contact position toward the separating position against the action of the second urging means, the separating claw is separated. It is effective to use the guide pin that comes into contact with the surface of the side facing the rotating body.

Further, according to the present invention, when the regulating means moves the separating claw from the sliding contact position toward the separating position against the action of the second urging means, the guide part is the It is effective if it is attached to a guide member provided so as to be substantially flush with the transport surface.

Further, in order to solve the above-mentioned problems, the present invention is characterized by including the fixing device according to any one of claims 1 to 3.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a copying machine using a fixing device according to the present invention. The copying machine 1 includes a reading section 3 for reading a document image, an image forming section 5 for forming an image, and a sheet feeding section for feeding a transfer material (recording material) P in order from above the copying machine 1. 7 and 7.

The reading unit 3 is provided on the top surface of the cover 9 that covers the surroundings, a contact glass 11 on which an original image (copy original) is set, and a contact glass 11 which can be opened and closed. A document holder 13 for holding the set copy original, and a photoconductor 17 for reading the copy original set on the contact glass 11
And an optical device (exposure means) 15 for forming an electrostatic latent image.

The image forming section 5 has a photoconductor (image carrier) 17 which rotates clockwise (see arrow) in the figure. A charging device (charging means) 19 that uniformly charges the surface of the body 17, a developing device (developing means) 22 that visualizes the electrostatic latent image of the photoconductor 17 as a toner image by the developing sleeve 20, and the photoconductor 1.
Transfer device (transfer means) 24 for transferring the toner image (visible image) of No. 7 to the transfer material P which is a recording sheet, and the photoconductor 17 by removing the toner remaining on the photoconductor 17 after the transfer.
And a photoconductor cleaning device 28 for cleaning.

Further, the fixing roller 30 as a rotating body for applying heat and the pressure roller 34 for pressing (pressurizing) the transfer material P toward the fixing roller 30 are located at the lower left of the photoconductor cleaning device 28 in the figure. And a fixing device 32 for thermally fixing the toner image transferred to the transfer material P. The transfer material P on which the toner image is fixed by the fixing device 32 is ejected to the ejection tray 45 and stacked.

The paper feeding section 7 is located at the lower part of the copying machine 1, and has a paper feeding cassette 33 for accommodating the transfer material P and one end side in the paper feeding direction of the paper feeding cassette 33 (upper right side in FIG. 1). ) For feeding the transfer material P in the paper feed cassette 33, and the transfer material P fed by the paper feed roller 35 is conveyed between the photoconductor 17 and the transfer device 24. And a transfer paper transport device 37.

The transfer paper transporting device 37 has a plurality of guide plates 39 with a transfer paper transporting path 40 which is folded back from the right side of the paper feed roller 35 in the drawing toward the space between the photoconductor 17 and the transfer device 24. And the first intermediate roller pair 41a and the second intermediate roller pair 41 are formed in the transfer paper conveyance path 40.
b and the registration roller pair 43 are arranged.

FIG. 2 is an enlarged explanatory view showing a fixing roller using the fixing device 32 according to the present invention and a separating claw 50 slidably contacting the roller, and FIG. 3 is an explanatory view of the separating claw 50 of FIG. 2 seen from the right side. 4 is a sectional view taken along line IV-IV in FIG.

2 to 4, the separation claw 50 has a claw portion 51 on one end side and a locking portion 52 protruding upward on the other end side.
Are provided respectively, and the bearing portion 53 is provided in the middle thereof. A support shaft 61 provided on the support member 60 penetrates the bearing portion 53, and the separation claw 50 is rotatable around the support shaft 61. The locking portion 52 of the separation claw 50 has a first end locked to a machine frame (not shown) or the like.
The other end of the spring 54 as an urging means of the
The elastic force of the spring 54 urges the elastic force in the direction in which the claw portion 51 is in sliding contact with the fixing roller 30.

The claw portion 51 of the separation claw 50 is a fixing roller 30.
The surface opposite to the surface opposite to the surface, that is, the surface on the lower surface side in FIG. 2, is guided to the paper discharge roller 44 on the left side, which is not shown in FIG. The transport surface 55 is configured as a flat transport surface. The separation claw 50 has a support shaft 61 fitted in a long hole 62 formed in the support member 60, and the extending direction of the long hole 62 is the tangent line of the sliding contact portion of the fixing roller 30 in the separation claw 50. It is almost parallel. Then, the separation claw 50 contacts the lower end of the elongated hole 62 with the support shaft 61 by a spring 64 as a second biasing means provided between the support shaft 61 and a locking portion 63 provided on the support member 60. It is held in contact position. The position where the support shaft 61 is at the lower end of the elongated hole 62 is the sliding contact position where the separation claw 50 is in sliding contact with the fixing roller 30, and the position where the support shaft 61 is at the upper end of the elongated hole 62 is the separation claw 50 is fixed. Laura 3
It is a separated position away from zero. The conveying surface 55 of the separation claw 50 at the separated position is elevated to the L position shown by the chain line in FIG.

In the fixing device 32 constructed as described above, when the transfer material P jams and pushes the separating claw 50 upward as described above, the support shaft 61 resists the spring 64 and the long hole 62.
And the separation claw 50 is separated from the fixing roller 30. Therefore, the fixing claw 50 is prevented from being damaged by the separation claw 50, but the pushing force of the transfer material P is large, and if the supporting shaft 61 reaches the upper end of the elongated hole 62 and is further pushed, depending on the pushing direction. The claws 51 may bite into the fixing roller 30, and the fixing roller 30 is damaged at this time.

Therefore, in order to solve such a problem, the fixing device 32 according to the present invention is located at a position close to the surface 56 of the claw portion 51 of the separation claw 50 facing the fixing roller and contacted by the pushed-up separation claw 50. Guide pin 6 as a regulation means
7 is planted in a guide member 65 described later.

When such a guide pin 67 is provided, when the separation claw 50 is pushed up, its surface 56 contacts the guide pin 67, and the separation claw 50 rotates counterclockwise around the support shaft 61 in FIG. Prevent it from moving. That is,
The separation claw 50 is pushed up and its surface 56 is guided by the guide pin 6.
7, the surface 56 is inclined so that the left side is upward in FIG.
Is rotated clockwise along the inclination. This rotation direction is the direction in which the claw portion 51 separates from the fixing roller 30, and thus the biting into the fixing roller 30 is prevented.

As described above, when the separation claw 50 is pushed up, the guide pin 67 prevents the claw portion 51 from rotating counterclockwise about the support shaft 61, that is, the direction in which the claw portion 51 bites into the fixing roller 30, and the fixing is performed. The roller 30 can be prevented from being damaged.

Further, in this embodiment, a guide member 65 is provided which the transfer material P contacts when the separation claw 50 is pushed up. The guide member 65 in the present embodiment is provided on the support member 60, but the guide member 65 is not the support member 6.
It may be separate from 0. However, the guide member 65
If it is provided apart from the separation claw 50, it may happen that depending on the form of the transfer material P, only the separation claw 50 pushes and does not come into contact with the guide member 65. According to the experiments conducted by the present inventor, all of the apparatuses using the fixing roller having a diameter of 3 cm, in which the distance between the guide member 65 and the separating claw 50 is set within 5 mm, are all good.

The guide member 65 has a guide surface 66 whose lower surface is substantially parallel to the conveying surface 55 of the separating claw 50. The guide surface 65 is formed on the transfer material P before the conveying surface 55 of the separating claw 50 moves up to the L position. It is provided so as to come into contact with. Further, the width of the guide surface 66 is a portion indicated by a symbol a in FIG. 4 from a perpendicular line passing through the center of the support shaft 61 to near the tip of the claw portion 51. This is because if the conveyance surface of the claw portion 51 is pushed to the left of the width a, the pushing force is clockwise with respect to the support shaft 61 in FIG. 4, that is, the claw portion 51 moves away from the fixing roller 30. Therefore, it is sufficient if the guide surface 66 of the guide member 65 is in the width a portion.

Thus, in the fixing device 32 of this embodiment, when the transfer material P is jammed and the separation claw 50 is pushed upward as described above, the transfer material P is guided by the guide surface 6 of the guide member 65.
Hit 6 Therefore, it is possible to prevent the separation claw 50 from being further pushed up, and thus the separation claw 50 is prevented from damaging the fixing roller 30 even if the amount of push-up of the transfer material P is larger than expected.

The guide pin 67 may be supported by anything, but like the present embodiment, the guide plate 652 is used.
If provided, it becomes easy to determine the positional relationship with the separation claw 50. Further, it is sufficient to prevent the fixing roller 30 from being damaged by providing either the guide member 65 or the guide pin 67, but as in the present embodiment, providing both of them provides a double safety measure. Will be more complete.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made. For example, although the rotating body is described as the fixing roller in the above-described embodiment, the rotating body may be a pressure roller, and the elastic belt or the film may be wound around any roller of a belt fixing device that is wound around a plurality of rollers. It can also be applied to a device in which the separating claw is arranged at the hanging position.

[0030]

According to the first and second aspects of the present invention, even if the separation claw moves from the sliding contact position to the separation position by the transfer material, the transfer material contacts the guide pin and the separation claw serves as the rotating body. It is possible to prevent bite.

According to the third aspect of the present invention, the installation position of the regulating means can be easily indexed, and it can be provided at the correct position with respect to the separating claw. According to the configuration of claim 4, it is possible to provide the image forming apparatus in which the rotating body is prevented from being damaged by the separating claw of the present invention.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing a copying machine using a fixing device according to the present invention.

FIG. 2 is an enlarged explanatory view showing a fixing roller using the fixing device according to the present invention and a separation claw slidingly contacting the roller.

FIG. 3 is a side view illustrating the separation claw shown in FIG. 2 as viewed from the right side.

4 is a cross-sectional view taken along the line IV-IV of FIG.

FIG. 5 is a schematic configuration diagram of a conventional fixing device.

[Explanation of symbols]

30 fixing roller 32 fixing device 50 separate nails 51 nails 54 spring 55 Transport surface 56 Face of fixing roller 60 Support member 61 Support shaft 63 spring 65 Guide member 66 Guide surface connector 67 Guide pin

Claims (4)

[Claims] 1. A rotating body, a claw portion slidably contacting the surface of the rotating body, and a separation claw mounted rotatably around a support shaft, and the claw portion slidingly contacting the rotating body. First urging means for urging a rotational force centering on the support shaft in the direction to the separation claw, a sliding contact position at which the claw portion slides in contact with the rotating body, and a spaced position away from the rotating body. And a second urging means for urging an elastic force for holding the support shaft in the sliding contact position. In a fixing device in which a side opposite to the side opposite to the rotating body is configured as a conveyance surface, the separation claw moves from the sliding contact position toward the separation position against the action of the second biasing unit. When separated, the separation claw is moved around the support shaft against the action of the first biasing means. Fixing apparatus characterized by comprising a regulating means for rotating in a direction away from the rotating body. 2. The fixing device according to claim 1, wherein the regulating means moves the separating claw from the sliding contact position toward the separating position against the action of the second urging means. The fixing device is a guide pin that comes into contact with the surface of the separation claw facing the rotating body. 3. The fixing device according to claim 1, wherein the separating means moves the separating claw from the sliding contact position toward the separating position against the action of the second urging means. The fixing device is characterized in that the guide portion is attached to a guide member provided so as to be substantially on the same plane as the transport surface when the fixing device is pressed. 4. An image forming apparatus comprising the fixing device according to any one of claims 1 to 3.