JPH08185076A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device enabling easy removal of a jammed paper by separating a heating roller and a pressure roller by the opening operation of at least one of a top cover and a rear cover in accordance with a place where a paper sheet is jammed. CONSTITUTION: The image forming device is provided with a freely turntable separating member 29 provided with a projection 30 pressed by the engaging parts 26b-26d of a rack member 26 (first actuating part) linked with the opening operation of the top cover 22, on one end side and a projection 31 pressed by the engaging recessed part 40 of a second actuating part 32 linked with the opening operation of the rear cover 36, on the other end side and a branch lever 29d engaged with the shaft 35 of the pressure roller 20 and constituted so that the pressure roller 20 is separated from the heating roller 19, linked with the opening operation of one of the top cover 22 and the rear cover 36, to facilitate the removal of the jammed paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image formation using a fixing unit for fixing a recording member on which a visible image is transferred by a printer, a copying machine or the like using electrophotography, by a pressure roller and a heating roller. Regarding the device.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, for example, a laser printer, a surface of a photosensitive drum is charged by a charging portion, and the charged portion is irradiated with information light by a laser to form an electrostatic latent image. The latent image is converted into a visible image by toner in the developing section, and this visible image is transferred by a transfer section onto a sheet, which is a recording member, which is conveyed by a conveying roller including a feed roller and a pinch roller pressed against the toner. After that, the paper is further conveyed, and the visible image is fixed on the paper by a fixing unit including a heating roller and a pressure roller, and is discharged onto a tray from a discharge port by a discharge roller through a discharge guide. Has become.

In the fixing unit of such a printer, a visible image on a sheet is fixed while being conveyed by a heating roller and a pressure roller pressed against the heating roller. Since the fixing unit is integrally configured so that the pressure roller is brought into pressure contact with the heating roller heated to a predetermined temperature, the sheet is heated by the heating roller when a paper jam occurs at the pressure contact portion. Since it is nipped by the strong force of the pressure roller and the pressure roller, it is very difficult to remove the paper.

In order to solve such a problem, in the conventional image forming apparatus, the paper jam in the fixing portion is eliminated as shown in FIG. A top cover 100 that can be opened and closed is formed on the upper surface of the main body 1 of the image forming apparatus. In the figure, the top cover 100
Shows a state in which is opened. This top cover 10
0 is provided with a pair of left and right arms 101, and is pivotably supported by a shaft 102 that is integrally rotatable with the arms 101. The shaft 102 is provided with an opening / closing member 104, which is fan-shaped and has teeth 103 formed on the periphery of the tip thereof, so as not to rotate. The teeth 103 of the opening / closing member 104 are the teeth 1 of the rack member 105.
06 is engaged with the rack member 105.
It is held by two pins 108, 108 inserted in the connector 7, and can be moved left and right. Then, on the side opposite to the teeth 106 of the rack member 105, that is, on the lower side in the figure, the first engaging portion 105a and the second engaging portion 105b are provided with the slope 10
An L-shaped stopper portion 109 is formed at the end of the step portion 5c in a substantially stepped shape.

On the left side of the rack member 105, a substantially V-shaped separating member 110 is rotatably provided around a support shaft 110a, and one end of the separating member 110 engages with a stepped portion of the rack portion 105. A convex portion 111 is formed and a hole 112 is formed at the other end, and the shaft 112 of the pressure roller 113 is formed in the hole 112.
14 is movably inserted. The pressure roller 11
3 is configured to be pressed upward by the spring 115 and come into pressure contact with the heating roller 116. An openable rear cover 118 is formed at the terminal end of the transport path 117 at the rear of the main body 1.

Therefore, when the top cover 100 is opened as shown in the drawing, the shaft 102 is rotated by the rotating motion of the opening of the top cover 100, and the opening / closing member 104 is rotated with the rotation of the shaft 102. This opening / closing member 104
The rotation of moves the rack member 105 to the right in the figure. As a result, the engaging protrusion 11 of the separating member 110
1 moves from the first engaging portion 105a to the second engaging portion 105b via the inclined surface 105c and is locked by the stopper portion 109. Then, the separating member 110 rotates clockwise around the support shaft 110a, and the end portion provided with the hole 112 is converted into a downward pressing operation and resisted by the urging force of the spring 115 to pressurize the roller. By pressing the shaft 114 of the 113 downward, the pressure roller 113 pressed against the heating roller 116 is separated to remove the jammed paper that is sandwiched.

Further, in the fixing unit of another conventional image forming apparatus, as shown in FIG. 6, when a paper jam occurs on the downstream side of the fixing unit, it can be released from the rear portion of the main body 1 at the end of the conveying path 117. The rear cover 118 provided at the opening is opened, and the lever 120 supported by the support shaft 119 is provided on one side of the conveyance path.
And a hole 112 is formed in the other end of the lever 120, and the shaft 114 of the pressure roller 113 is inserted into the hole 112. When a jam occurs, the operation unit 121 is inserted. By pushing up in the direction of arrow A, the spring 115 is pushed down, and the heating roller 116 and the pressure roller 113, which were in pressure contact with each other, are separated from each other, so that the jammed paper can be removed. It should be noted that this conventional one is not provided with a mechanism for holding the lever 120 in a state where the pressure roller 113 is separated from the heating roller 116.

[0008]

As described above, when a paper jam occurs in the conventional fixing unit, when the jam occurs while the leading edge of the paper is sandwiched between the heating roller and the pressure roller, Although there is an advantage that both rollers are separated from each other when the top cover is opened, both the top cover and the rear cover must be opened if a jam occurs when at least the trailing edge of the paper holds both rollers. There is a problem that jam can not be eliminated,
Further, in the case of opening the rear cover to eliminate the jam, the lever for separating the pressure roller from the heating roller must be constantly operated, that is, pushed up as described above, and there is a problem that the paper jam processing is complicated.

Therefore, the present invention has been made in view of the above problems, and makes it possible to separate the heating roller and the pressure roller from each other regardless of whether the top cover on the upper surface of the main body or the rear cover on the side surface of the main body is opened or closed. It is an object of the present invention to provide an image forming apparatus that is capable of easily performing jam processing regardless of the position of a paper jam.

[0010]

SUMMARY OF THE INVENTION The present invention relates to an image forming apparatus for developing a latent image formed on an image carrier to form an image on a recording member, from the image forming section to the downstream side in the conveying direction of the recording member. Of a heating roller and a pressure roller which are axially supported in parallel with each other and are arranged so as to be able to come into contact with and separate from each other, and an urging means for urging one of these rollers toward the other. A fixing unit for fixing an image, a separating member for separating one of the biased rollers from the other roller against the biasing force of the biasing means, and the both rollers formed on the upper part of the apparatus main body. And a top cover rotatably provided to open and close an opening including the upstream side in the recording member conveying direction, and a first actuating member for interlocking with the opening operation of the top cover and operating the separating member in the direction opposite to the urging direction. And the above And a rear cover rotatably provided to open and close an opening formed in the main body side portion on the downstream side in the recording member transporting direction, and to move the separating member in the urging direction in conjunction with the opening operation of the rear cover. It is composed of two actuating members, and releases the pressure contact state of both rollers of the fixing unit in conjunction with the opening operation of at least one of the rear cover and the top cover.

[0011]

When a jam occurs in the main body and the jammed recording member is removed, depending on the location of the jam, no matter whether the top cover or the rear cover is opened, the separating member is in a pressure contact state with the heating roller. It can be separated from the pressure roller. Therefore, if the user can open the rear cover and then clear the jam, it is not necessary to open the top cover.If the user can clear the jammed paper by opening the top cover, then open the rear cover. Good.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an internal configuration of a laser printer main body 1 as an image forming apparatus, and an image carrier unit 4 including a photosensitive drum 3 as a cylindrical image carrier at a substantially center of a housing 2. Are arranged. The image carrier unit 4 is provided with a charging unit 5 for charging the surface of the photosensitive drum 3, a cleaning member (not shown), a waste toner storage chamber, and a discharging unit 5a for discharging the drum surface.

Further, around the photosensitive drum 3, an exposure unit 6a for forming an electrostatic latent image by the laser beam from the exposure unit 6 and an electrostatic latent image formed on the photosensitive drum 3 by the laser beam from the exposure unit 6 are provided. A developing unit 7 that develops an image into a toner image, that is, a visible image using toner, a transfer device 8 that transfers the visible image on the photosensitive drum 3 to a sheet P that is a recording member, and a sheet P to which the visible image is transferred. A static eliminator 9 for removing charges on the back surface is arranged in this order. The developing unit 7 includes a developing sleeve 7 a that attaches toner to the photosensitive drum 3. The image carrier unit 4,
The image forming unit 10 is composed of the exposure unit 6a, the developing unit 7, the transfer unit 8, and the static eliminator 9.

In the lower part of the housing 2, a paper feed cassette 11 containing paper P is mounted, and the paper feed cassette 1
The uppermost sheet P of the sheets P stacked in 1 is pulled out by the sheet feeding roller 12, and is conveyed to the image forming unit 10 by a plurality of conveying rollers 14 provided on a conveying path 13 as a recording member conveying path. It A fixing unit 15 is arranged on the downstream side of the image forming unit 10, and the paper P fixed by the fixing unit 15 is sent to the upper part of the main body 1 by a conveyance roller 14 through a paper discharge guide 16 and a recording surface thereof. The paper is discharged downward to the tray 18 by the paper discharge roller 17.

The carrying path 13 is provided with a carrying roller 14, a fixing section 15, a carrying roller 14, from the upstream side to the downstream side.
A paper ejection guide 16 and a paper ejection roller 17 are provided in this order. A drive motor (not shown) that drives the transport roller 14
The paper P fed from the paper feed cassette 12 is guided to the transfer device 8 along the transport path 13 to transfer a visible image,
The visible image is fixed by the fixing unit 15 by heating and pressing, and then discharged onto the discharge tray 18.

The fixing section 15 is composed of a heating roller 19 and a pressure roller 20 which are opposed to each other for fixing a visible image of toner on the sheet P. The heating roller 19 and the pressure roller 20 can sandwich and convey the sheet P on which the visible image is transferred. The heating roller 19 is heated to a predetermined temperature by a heating means (not shown) such as a heater provided inside, and the pressure roller 20 is attached to the heating roller 19 side by a spring 21 which is an urging means. It is urged to constantly come into pressure contact with the pressure roller 20. The spring 21 is attached to a protrusion 21b provided on the spring storage portion 21a.

An openable and closable top cover 22 is formed on the upper surface of the main body 1 for replacement of the photosensitive drum 3, removal of jammed paper P, cleaning of the inside, and the like. Arm 23 is provided,
It is rotatable by being pivotally supported by a shaft 24 which rotates integrally with the arm 23. An opening / closing member 25 as a first actuating member, which is formed in a fan shape on the shaft 24 and has teeth 25a formed on the outer periphery thereof, is provided so as to be prevented from rotating. The teeth 25a of the opening / closing member 25 are meshed with the teeth 26a of the rack member 26 serving as the first actuating member, and the rack member 26 has a long hole 27 formed therein.
By inserting a pair of pins 28, 28 linearly arranged in the left-right direction in the figure into the housing 2 into the elongated hole 27, the housing 2 is attached to the housing 2 so as to be movable in the left-right direction.

Further, a first engaging portion 26b and a second engaging portion 26c are provided on the side opposite to the side where the teeth 26a of the rack member 26 are provided, that is, on the lower side in the figure, and the engaging portion 26.
A third engaging portion 26d formed of an inclined surface connecting b and 26c is formed. A stopper 26e is provided at the end of the second engaging portion 26c.

The housing 2 is provided with a separating member 29 which is fitted in a shaft 29a provided in the housing 2 into a shaft hole 29b and is rotatably supported. The separating member 29 is formed in a substantially T-shape including a substantially linear main rod 29c and a branch rod 29d protruding from the middle portion of the main rod 29c to one side. A protrusion 30 is provided on one end side 29e of the main rod 29c,
A protrusion 31 is similarly provided on the other end side 29f. The protrusion 31 is adapted to be in sliding contact with the first to third engaging portions 26b, 26c, 26d provided on the rack member 26, and these engaging portions are engaged when the rack member 26 moves from the left side to the right side in the drawing. It is engaged with the portions 26b to 26c and is pushed down, that is, moved in the drawing.

Further, the projection 31 is adapted to engage with a locking portion 33 provided on a second actuating member 32 which will be described later. Further, a hole 34 is provided at the tip of the branch rod 29d, and the shaft 35 of the pressure roller 20 is inserted into or engaged with the hole 34. The shaft hole 29b is provided at a position where the branch rod 29d moves downward when one end side 29e of the main rod 29c moves downward and the other end side 29f moves upward in the figure. As a result, when the branch rod 29d is moved downward, that is, pushed down, the pressure roller 20 is pushed down against the urging force of the spring 21 and separated from the heating roller 19.

A rear cover 36 is provided on a surface of the rear end of the main body 1 facing the conveying direction at the end of the conveying path 13, and a handle 37 for opening is formed on the rear cover 36. Rear cover arms 38 formed in a substantially V shape on both sides are fixedly attached to the rear cover 36 at one end side of the V shape, and the other end side is rotatably attached to a rear cover shaft 39 provided in the housing 2. Has been. An engaging recess 40 is formed at the top of the V-shaped rear cover arm 38, and the engaging recess 40 has the other end 29f of the main rod 29c of the separating member 29 when the rear cover 36 is opened.
The projection 31 provided on the above is engaged, and this state is maintained. The rear cover arm 3
Reference numeral 8 constitutes a second operating member 32 provided on the rear cover 36.

The locking recess 40 also has a function of engaging with the projection 31 of the separating member 29 when the rear cover 36 is opened and holding the open state. Further, a detection sensor 41 for detecting the conveyance of the fixed paper P is provided near the pair of conveyance rollers 14, 14.

In such a structure, the paper feed cassette 1
The sheet P pulled out from the sheet feeding roller 12 of the main body 1 is conveyed by the conveying roller 14 to the image forming unit 10. On the other hand, the photosensitive drum 3 is charged by the charging unit 5 while being rotated, and the charged portion is scanned with the information light 6a from the exposure unit 6 to form an electrostatic latent image. This electrostatic latent image is developed by the developing unit 7, and this visible image is transferred by the transfer device 8 to the paper P conveyed from the paper feed cassette 11. The paper P on which the image is transferred is fixed to the fixing unit 15.
The sheet is fixed by, and is discharged onto the tray 18 through the sheet discharge guide 16 and the sheet discharge roller 17.

Next, the jam processing of the laser printer having the above structure will be described. First, when a jam occurs when the front end of the paper P is nipped by the fixing unit 15 (see FIG. 2), the detection sensor 41 inside the main body 1 detects the absence of the paper P, and the upper surface of the main body 1 is detected. The user is informed by a display section (not shown) formed on the operation panel, the user opens the top cover 22 to remove the jammed paper P (not shown), and removes the developing unit 7 and the image carrier 4.

At this time, by opening the top cover 22, the arm 23 formed integrally with the top cover 22.
Rotates the opening / closing member 25 around the shaft 24. By this rotation operation, the teeth 25a of the opening / closing member 25 and the rack member 2
Since the teeth 26a of No. 6 mesh with each other, the rack member 26 is guided by the pins 28, 28 and moves rightward in the drawing. Along with this movement, the protrusion 30 formed on the one end side 29e of the separating member 29 is guided from the first engaging portion 26b of the rack member 26 to the third engaging portion 26d and moved by the stopper 26e of the second engaging portion 26c. To stop. By this movement, the separating member 2
9 rotates clockwise about the shaft 29a, and the separating member 29
The hole 34 formed in the branch rod 29d at the intermediate portion of the shaft slides with the shaft 35 inserted, and the spring 21 that is urged by pushing down is pushed down to press the pressure roller 2
0 is separated from the heating roller 19. In this state, the jammed paper P can be easily removed.

Next, as shown in FIG. 3, when a paper jam occurs in a state where the vicinity of the paper discharge guide 16, that is, the rear end side of the paper P is sandwiched between the pressure roller 20 and the heating roller 19, the paper discharge is performed. It is easier to open the rear cover 36 near the guide 16 for easier processing. In this case, by pulling the handle 37 and opening the rear cover 36, the locking recess 40 of the second operating member 32 formed integrally with the rear cover 36.
Raises the protrusion 31 on the other end 29f of the separating member 29, and the branch rod 29d of the separating member 29 pushes the shaft 35 downward to lower the pressure roller 20 urged by the spring 21.
The remaining jammed paper P can be easily removed by separating it from the heating roller 19 that was in pressure contact.

1 to 3, the opening / closing member 25 and the rack portion 26, which are the first actuating members, are formed separately from the top cover 22, respectively. As shown in FIG. The operating portion 42 can be integrally provided as a first operating portion. 1 to 3, the second actuating member 32 is provided integrally with the rear cover 36, but this is composed of, for example, a fan-shaped opening / closing member and a rack member (not shown), and is separated from the rear cover. It may be provided in the.

In the embodiment, one end side 2 of the separating member 29 is
By pushing 9e downward and pushing the other end side 29f upward,
The pressure roller 20 is separated from the heating roller 19 by rotating about the shaft 29a, and the shape of the separating member 29 is formed in a substantially T shape. However, the shape of the separating member is not limited to this. It may be formed in any shape as long as it is engaged with the shaft 35 of the pressure roller 20 so as to separate the pressure roller from the heating roller via the shaft 35 when rotated about the dynamic fulcrum. . It is needless to say that the separating member 29 may be rotated in the opposite direction to that shown in FIGS. 1 to 3, and any direction may be adopted as long as the pressure contact of the fixing portion 15 can be released when the separating member is rotated. Further, the detection sensor 41 for detecting the conveyance of the paper P simply detects the occurrence of a jam in the present invention, but the sensor 41 detects whether a jam occurs on the upstream side or the downstream side of the fixing unit 15. It is also possible to provide the user with a determination function and to inform the user which of the top cover 22 and the rear cover 35 is opened to quickly remove the jammed paper P.

[0029]

As described above, according to the present invention, when a jam occurs when the tip of the recording member is clamped by the fixing unit, the top cover is opened to interlock with the jam. The pressure contact state between the pressure roller and the heating roller in the fixing section is released to facilitate jam processing, and if a jam occurs when the trailing edge of the recording member is clamped in the fixing section, open the rear cover. The pressure contact state between the pressure roller and the heating roller is released in association with the operation, and the jam processing can be easily performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a configuration of an image forming apparatus of the present invention.

FIG. 2 is a sectional view of an essential part of the same invention with the top cover opened.

FIG. 3 is a cross-sectional view of a main part of the same invention with a rear cover opened.

FIG. 4 is a sectional view of an essential part of a modified example of the present invention.

FIG. 5 is a cross-sectional view of a main part of a conventional image forming apparatus with a top cover opened.

FIG. 6 is a cross-sectional view of essential parts of a conventional image forming apparatus with a rear cover opened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 main body 2 housing 4 image carrier 10 image forming part 15 fixing part 19 heating roller 20 pressure roller 21 spring (biasing means) 22 top cover 25 opening / closing member (first operating member) 26 rack member (first operating member) ) 29 Separation member 32 Second operation member 36 Rear cover P Paper (recording member)

Claims (1)

[Claims] 1. An image forming apparatus for developing a latent image formed on an image carrier to form an image on a recording member, wherein the image forming unit is axially supported in parallel with each other on the downstream side in the conveying direction of the recording member. And a fixing unit configured to fix a visible image on the recording member, which includes a heating roller and a pressure roller which are arranged so as to be able to come into contact with and separate from each other, and a biasing unit which biases one of these rollers against the other. A separating member for separating one of the biased rollers from the other roller against the biasing force of the biasing means, and an upstream side of the both rollers formed in the upper part of the apparatus main body in the recording member conveying direction. A rotatably provided top cover for opening and closing an opening including the opening, a first actuating member for interlocking with the opening operation of the top cover and operating the separating member in a direction opposite to the urging direction, and a recording member for both rollers. Transport direction A rear cover rotatably provided for opening and closing an opening formed in the main body side portion on the flow side; and a second actuating member for operating the separating member in the urging direction in conjunction with the opening operation of the rear cover, An image forming apparatus which releases the pressure contact state of both rollers of the fixing unit in conjunction with the opening operation of at least one of the rear cover and the top cover.