JPH08272260A - Fixing mechanism for image forming device - Google Patents

Abstract

PURPOSE: To provide a fixing mechanism for use in an image forming device, which prevents a decrease in the temperature of a roller pair, is easy to open and close and has a simple structure. CONSTITUTION: The mechanism comprises the roller pair 29, consisting of a heating roller 27 and a pressure roller 28, used for fixing a toner image to paper, a holding frame 34 by which a claw 36 for separating the paper sticking to the heat roller 27 is supported near the roller 27 and on the paper ejection side, a guide 55 arranged further downstream than the claw 36 in a carrying path, and a heat insulating cover 32 capable of surrounding the roller pair 29. The heat insulating cover 32 holds the guide 55 between the position where it uncovers the carrying path of the roller pair 29 on the paper ejection side and the position where it covers the path, and can be opened/closed independently from the holding flame 34. Further, even when the heat insulating cover 32 is in the uncovering position, the holding flame 34 surrounds at least a pan of the heating roller 27 and restrains the heat diffusion of the heating roller 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing mechanism of an image forming apparatus, and more specifically, a roller pair for fixing a toner image on a sheet, which is composed of a heating roller and a pressure roller in an image forming apparatus such as a laser printer. A claw member holding frame that supports a claw member that separates the sheet attached to the roller near at least one of the rollers on the discharge side, a sheet guide unit that is disposed on the downstream side of the claw member in the transport path, and a pair of rollers around the roller pair. The present invention relates to a fixing mechanism including a heat insulating cover that can be covered, and to an improvement of a heat insulating cover that removes a paper jam of a sheet discharged from a roller pair and prevents a temperature decrease of the roller pair.

[0002]

2. Description of the Related Art In a fixing mechanism of an image forming apparatus, protection and inspection around a roller pair composed of a heating roller and a pressure roller, removal of paper jam of a sheet discharged from the roller pair, prevention of temperature decrease of the roller pair, etc. A cover (insulation cover) is attached for. A claw member holding frame that supports a claw member that separates the paper attached to the roller is attached to the cover, and the claw member rotates between the position where the claw member contacts the roller and the position where the claw member separates as the cover is opened and closed. Is configured. Further, the paper guide means is arranged on the claw member holding frame on the downstream side of the claw member in the conveying path. In such a configuration, when the cover is opened, the claw member holding frame, the claw member attached to the holding frame, and the paper guide unit are lifted together with the cover, and the roller pair and the conveyance path on the paper discharge side of the roller pair are formed. It will be open.

[0003]

In the above-described conventional fixing mechanism of the image forming apparatus, for example, when a paper jam occurs, the cover is opened and the roller pair and the discharge path of the roller pair on the discharge side are opened. At this time, since the opening of the cover becomes large, the temperature of the pair of rollers in the heated state is significantly reduced after the paper jam processing is completed. Therefore, it takes a long time for the pair of rollers to return to a temperature at which stable fixing operation is possible. Further, since the cover is opened and closed together with the claw member holding frame, the claw member attached to the holding frame, and the sheet guiding means, a considerable force is required for opening and closing. Further, there is a case where the claw member attached to the holding frame slides on the roller peripheral surface at the time of opening and closing to damage the roller, and a mechanism portion for retracting the claw member from the roller peripheral surface in association with the opening and closing operation is provided. Becomes complicated.

An object of the present invention is to provide a fixing mechanism for an image forming apparatus which prevents the temperature of the roller pair from decreasing and is easy to open and close and has a simple structure.

[0005]

According to the present invention, at least one of a roller pair consisting of a heating roller and a pressure roller for fixing a toner image on a sheet and a claw member for peeling the sheet attached to the roller is provided. Fixing mechanism of the image forming apparatus including a claw member holding frame that supports the vicinity of the sheet discharge side, a sheet guide unit that is disposed on the downstream side of the claw member in the conveying path, and a heat insulating cover that can cover the periphery of the roller pair. In, the heat insulating cover can be opened and closed while holding the paper guide means and separated from the claw member holding frame between the position where the discharge side conveyance path of the roller pair is opened and the position where it is closed. Is composed of
Further, the claw member holding frame is arranged so as to cover at least a part of the periphery of the heating roller to suppress heat dissipation of the heating roller even when the heat insulating cover is at the open position. A fixing mechanism is provided.

The image forming apparatus in the present invention refers to a copying machine, a printer, a facsimile or the like which uses a powder developer and which is provided with a pair of fixing rollers.
The roller pair in the present invention refers to a pair of rollers that rotate in opposite directions in a pressure contact state and can convey a sheet by a frictional force between the rollers. The roller surface may be made of metal such as aluminum or stainless steel, rubber, or synthetic resin.

The claw member according to the present invention is one which is disposed on the paper discharge side of the fixing roller pair and has a blade tip at the tip for peeling off the paper adhering to the roller surface due to static electricity or toner fusion. As expected. The claw member may be made of metal, ceramic, or synthetic resin. The synthetic resin is preferably a hard synthetic resin having heat resistance and wear resistance, particularly polyimide, polyamide, or nylon.

The claw member holding frame in the present invention means a member for disposing and supporting one or a plurality of claw members so that the blade edge of the claw member contacts the roller peripheral surface over the sheet feeding width. The claw member holding frame is preferably configured such that the blade edge of the claw member is brought into contact with the roller peripheral surface by an elastic member. The sheet guiding means in the present invention is disposed on the sheet discharging side of the fixing roller pair, preferably on the downstream side of the claw member, and guides the sheet discharging from the roller pair to the downstream conveying path over the sheet feeding width. A member.

The heat insulating cover in the present invention not only prevents the temperature drop of the roller pair, but also protects and inspects the surroundings of the roller pair, and removes the paper jam of the paper discharged from the roller pair in the main body of the image forming apparatus. Insert the attached cover. Paper jam is a state in which a part of the paper comes into contact with the claw member of the paper peeling mechanism inside the device or near the discharge side of the roller pair, which is blunted due to wear, and the jammed paper is bent (jam state). It means that the continuous feeding is stopped. The claw member holding frame is
It is preferable that when the heat insulating cover is in the open position, the claw member is rotatably supported between a position where the claw member contacts the roller and a position where the claw member separates from the roller.

[0010]

According to the fixing mechanism of the image forming apparatus of the present invention, when the paper fed by the fixing roller pair adheres to the peripheral surface of the roller and is discharged to the discharge side of the roller pair, The paper comes into contact and is peeled off from the roller. When the heat insulating cover is opened, the paper discharge side transport path of the roller pair is opened, and the processing such as paper jam can be easily performed. At this time, since the paper guide means is held by the heat insulating cover, the paper discharge side transport path is opened over a wide range. Since the claw member holding frame remains at the original position, even if the heat insulating cover is at the open position, at least a part of the periphery of the heating roller is covered to suppress heat dissipation of the heating roller.

When the heat insulating cover is in the open position and when it is desired to further open the upstream side of the discharge side transport path of the roller pair, that is, the transport path near the claw member, the claw member holds the claw member by the roller. It is rotated from the position where it touches to the position where it separates. As a result, the paper discharge side conveyance path is opened over a wider area up to the vicinity of the roller pair, and processing such as paper jam can be easily performed.

[0012]

Embodiment 1 FIG. 1 schematically shows a digital type electrophotographic image forming apparatus to which an embodiment of the present invention is applied. In the figure, a document placing table 2 and a document cover 3 are arranged on the upper part of the apparatus main body 1. An optical system 4 is arranged below the document table 2. The optical system 4 is composed of an exposure lamp 5, mirrors 6, 7, 8 and a CCD camera 9. Below the optical system 4, a laser unit 11 and a photosensitive drum 12 are arranged. The laser unit 11 includes a laser output device 13, a polygon mirror 14, and a polygon mirror scanning motor 15.

Around the photosensitive drum 12, a developing device 16 for developing an electrostatic latent image, a transfer charger 17 for transferring a toner image onto recording paper, a cleaning device 18, and a main charger 20 are arranged. Photoconductor drum 1
A conveyance belt 19, a fixing device 21, and a paper discharge roller 22 are arranged on the left side of FIG. The fixing device 21 is
A paper peeling mechanism 30 is arranged on the paper discharge side.

On the other hand, on the right side of the apparatus main body 1 in the drawing, a paper feed cassette 23 is detachably arranged. A paper transport path 24, a registration switch 25, and a registration roller 26 are arranged between the paper feed cassette 23 and the photosensitive drum 12. The image information of the document placed on the document table 2 is read by the CCD camera 9 and converted into a digital signal. Laser light modulated based on this signal is emitted from the laser output device 13. The laser light is applied to the photoconductor drum 12 via the polygon mirror 14 and the mirror 10 to form an electrostatic latent image on the drum surface.

The sheet sent from the sheet feeding cassette 23 passes through the sheet conveying path 24 and is detected by the registration switch 25. The registration roller 26 determines the paper feed timing with respect to the rotation of the photoconductor drum 12 and sets the paper to the photoconductor drum 12
Send to. The transfer charger 17 transfers the toner image on the photosensitive drum 12 onto the sheet. The sheet is conveyed to the fixing device 21 by the conveyor belt 19. The sheet conveyed to the fixing device 21 is nipped between the heating roller 27 and the pressure roller 28, and the unfixed toner image on the sheet is fixed. The paper is discharged to the outside by the paper discharge roller pair 22.

Details of the fixing device 21 will be described below with reference to the drawings. As shown in FIG. 2, the fixing device 21 includes a fixing roller pair 29 including a heating roller 27 and a pressure roller 28, a sheet peeling mechanism 30, and a fixing device cover 33 including a fixing cover 31 and a heat insulating cover 32. I have it. The heating roller 27 is internally provided with a heater for fusing toner, and is rotatably arranged so that its peripheral surfaces are in pressure contact with the pressure roller 28. A sheet peeling mechanism 30 is installed on the downstream side of the heating roller 27 in the conveying path.
The sheet peeling mechanism 30 mainly includes a claw member holding frame 34, a support shaft 35, a claw 36, and a coil spring 37.

The main frame 34a of the holding frame 34 has a support shaft 3 on its main surface 34a.
A plurality of plate-shaped bearing members 38 rotatably supporting the sheet 5 are arranged at substantially equal intervals in the width direction of the paper S (front-back direction of the paper). An extension member 39 extending near the peripheral surface 27a of the heating roller 27 is provided on the upstream side of the main surface 34a in the sheet feeding direction.
Spring engaging members 40 extending upward are formed at the downstream end portions, respectively. The extension member 39 is the heating roller 27.
It is arranged close to the roller peripheral surface 27a on the paper discharge side, and heat dissipation from the roller 27 is suppressed. A locking portion 40 for locking one end of the coil spring 37 is provided on the spring locking member 40.
a is formed.

Further, one end of an arm 41 is fixed to the main surface 34a of the holding frame 34. The other end of the arm 41 is rotatably connected around a support shaft 42 arranged in the apparatus body 1. With such a configuration, the sheet peeling mechanism 30 is rotatably supported between the position where the claw 36 contacts the roller 27 and the position where the claw 36 contacts the roller 27 when the heat insulating cover 32 is at the open position, as described later. There is. The support shaft 35 is rotatably arranged so as to pass through the bearing member 38 arranged on the main surface 34a, and the bearing members 38 at both ends arranged on the main surface 34a.
It has a length that can be supported by. A plurality of claws 36 are non-rotatably arranged at substantially equal intervals in the axial direction of the support shaft 35.

The claw 36 is a substantially L-shaped plate-like piece, which is integrally formed by using polyamide resin as a material. Nail 36
A blade edge 51 that abuts the peripheral surface 27a of the heating roller 27 and is capable of peeling off the paper attached to the peripheral surface is provided in the lower part of the. A through hole 52 for penetrating and fixing the support shaft 35 is formed above the blade edge 51. At the top of the claw 36,
A locking groove 53 for locking one end of the coil spring 37 is formed. A coil spring 37 is stretched between the locking groove 53 and the spring locking portion 40a of the holding frame 34.

The coil spring 37 is attached so that one end on the side of the locking portion 40a with respect to the sheet feeding direction A is located below the other end of the locking groove 53, and the upper portion of the claw 36 is located downstream of the sheet feeding direction A. It is urged toward the side. As a result, the biasing force of the coil spring 37 causes the pawl 36 to rotate around the support shaft 35 with the locking groove 53 as a force point and the blade tip 51 as an action point so that the blade tip 51 is brought into light contact with the peripheral surface 27 a of the roller 27. There is. A heat insulating cover 32 is arranged above the paper peeling mechanism 30.

The heat insulating cover 32 is a generally L-shaped member mounted rotatably around a support shaft 54 arranged near the downstream end of the fixed cover 31 in the sheet feeding direction. The peeling mechanism 30 is configured to cover the peeling mechanism 2 in a plane. The cover 32 is made of polycarbonate resin and is stable against heat radiated from the roller pair 29. The cover 32 is disposed inside the apparatus main body 1 integrally with the roller pair 29 and the paper peeling mechanism 30, and is slid from the side surface of the apparatus main body 1 to be exposed from the apparatus main body 1. It is configured so that it can be opened and closed between a position where the road is opened and a position where the road is closed. A guide 55 is attached to the lower end of the cover 32 as a paper guide means.

The guide 55 has a length that covers the width direction (front-back direction of the paper surface) of the conveyance path, and extends in the paper feed direction for guiding the paper S discharged from the roller pair 29 to the paper discharge roller pair 22. A plurality of parallel ribs are formed on the lower surface (not shown). When the sheet fed to the fixing device 21 by the roller pair 29 adheres to the roller peripheral surface 27a and is ejected to the sheet ejection side, the sheet comes into contact with the blade edge 51 abutting the roller peripheral surface 27a and the sheet is ejected. It is peeled off from the peripheral surface 27a. As a result, winding of the paper around the roller 27 and jamming of the paper are prevented.

As shown in FIG. 3, when the heat insulating cover 32 is opened, the discharge side conveying path of the roller pair 29 is opened, and the processing such as paper jam can be easily performed. At this time, since the guide 55 is held by the heat insulating cover 32, the paper discharge side conveyance path is opened over a wide range. Further, since the holding frame 34 remains at the original position, even when the heat insulating cover 32 is at the open position, the paper peeling mechanism 30, especially the holding frame 34 having the extending member 39, surrounds the roller pair 29. It is coated to suppress the heat dissipation of the heating roller 27. Incidentally, conventionally, it took about 3 minutes for the heating roller to return to the stable warmed state after the processing such as paper jam, but in the above configuration, it can be restored in less than 1 minute.

When the heat insulating cover 32 is in the open position, and when it is desired to further open the conveyance path near the claw 36 which is on the upstream side of the paper discharge side, as shown in FIG. It is rotated around the support shaft 54 from a position in contact with the roller 27 to a position away from it. As a result, the discharge-side transport path is opened to a wider area up to the vicinity of the roller pair 29, and the processing such as paper jam on the upstream side can be easily performed. At this time, since the blade edge 51 of the claw 36 is separated from the roller peripheral surface 27a without sliding, damage to the roller peripheral surface 27a can be minimized. In the above configuration, the heat insulating cover 3
Since the sheet 2 is opened and closed with the sheet peeling mechanism 30 separated, the operation force required for opening and closing can be small.

[0025]

According to the fixing mechanism of the image forming apparatus of the present invention, when the heat insulating cover is opened, the discharge side conveying path of the roller pair is opened. At this time, since the paper guide means is held by the heat insulating cover, the paper discharge side conveyance path is opened over a wide range, and the processing such as paper jam can be easily performed.

Since the claw member holding frame remains in the original position in the separated state when the heat insulating cover is opened, it covers at least a part of the periphery of the heating roller even when the heat insulating cover is in the open position. The heat dissipation of the heating roller is suppressed. Therefore, the time required for the heating roller to return to the stable warmed state after the processing such as paper jam is remarkably shortened.

Since the heat insulating cover is opened and closed with the claw member holding frame separated, the operating force required for opening and closing can be small. If the claw member holding frame is configured to rotatably support between the position where the claw member contacts the roller and the position where the claw member contacts the roller when the heat insulating cover is in the open position, the paper discharge side conveyance path is further reduced. It opens up to a wider area up to the roller pair and can easily handle paper jams. At this time, since the claw member does not slide on the roller peripheral surface, damage to the roller peripheral surface is prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic image forming apparatus including a fixing mechanism according to an embodiment of the present invention.

FIG. 2 is a front view showing the positional relationship of the fixing mechanism when the heat insulating cover is closed.

FIG. 3 is a diagram corresponding to FIG. 2, showing a positional relationship of the fixing mechanism when the heat insulating cover is opened.

FIG. 4 is a diagram corresponding to FIG. 2, showing a positional relationship of the fixing mechanism in a state in which a claw member holding frame is opened.

[Explanation of symbols]

 1 Laser Printer (Image Forming Device) 21 Fixing Device 27 Heating Roller 27a Roller Circumferential Surface 28 Pressure Roller 29 Roller Pair 30 Paper Peeling Mechanism 32 Heat Insulation Cover 34 Claw Member Holding Frame 35 Spindle (Rotation Support Point of Claw Member) 36 Claw (Claw member) 37 Coil spring 39 Extending member 42 Support shaft (opening and closing fulcrum of claw member holding frame) 51 Blade edge 54 Support shaft (opening and closing fulcrum of heat insulating cover) 55 Guide

Claims (2)

[Claims] 1. A pair of rollers composed of a heating roller and a pressure roller for fixing a toner image on a sheet, and a claw member for supporting a claw member for peeling the sheet adhering to the roller in the vicinity of the discharge side of at least one roller. In a fixing mechanism of an image forming apparatus, which comprises a holding frame, a paper guide unit arranged on the downstream side of the pawl member in the conveying path, and a heat insulating cover capable of covering the periphery of the roller pair, the heat insulating cover is the roller. Between the position where the pair of paper discharge side conveyance paths are opened and the position where they are closed, the paper guide means is held and separated from the claw member holding frame so that it can be opened and closed. The fixing mechanism of the image forming apparatus, wherein the holding frame is arranged so as to cover at least a part of the periphery of the heating roller even when the heat insulating cover is at the open position to suppress heat dissipation of the heating roller. 2. The claw member holding frame is rotatably supported between a position where the claw member comes into contact with the roller and a position where the claw member is separated from the roller when the heat insulating cover is at the open position. 1. The fixing mechanism of the image forming apparatus according to 1.