JP2003287973A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein a recording material jammed in a fixing means can be easily removed from the fixing means. <P>SOLUTION: An opening/closing cover 80 is arranged on the apparatus surface parallel to the axial direction of a pressure roller 62, and a separating mechanism 70 of separating the pressure roller 62 from a heat roller 61 against the energizing force of an energizing means 66 when the cover 80 is opened is arranged between the cover 80 and the pressure roller 62. The separating mechanism 70 is provided with a cam 72a, and the pressure roller 62 is separated based on the rotation of the cam 72a. A pair of links 71 and 72 for the separating mechanism is constituted so as to release the connection. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a facsimile or a copying machine, which forms an image by using an electrophotographic technique. In particular, it relates to the fixing means or paper jam prevention.

2. Description of the Related Art Generally, an image forming apparatus using electrophotography has a photosensitive member having a photosensitive layer on its outer peripheral surface, a charging unit for uniformly charging the outer peripheral surface of the photosensitive member, and a charging unit for charging the outer peripheral surface of the photosensitive member. Exposing means for selectively exposing the charged outer peripheral surface to form an electrostatic latent image, and a visible image by applying toner as a developer to the electrostatic latent image formed by the exposing means. (Toner image) developing means, transfer means for transferring the toner image developed by the developing means to a recording material such as a sheet to be transferred, and fixing the toner image transferred to the recording material on the recording material. And fixing means. The fixing means includes a heat roller and a pressure roller that is urged by the urging means to press against the heat roller, and the toner image is formed by passing the recording material through the pressure contact portion of both rollers. A fixing unit that melts and fixes the recording material is known.

In such an image forming apparatus, paper jam may occur at the fixing means. Therefore, in the conventional device, an openable cover is provided in the device case near the fixing unit so that the user can remove the jammed paper (recording material), and the lever exposed when the cover is opened. By rotating the pressure roller, the pressing of the pressure roller against the heat roller is released to make it easier to take out the recording material, or a knob is provided at the end of the pressure roller and the recording material jammed by turning the knob. Was taken out.

[0003]

In the conventional image forming apparatus described above, when the recording material is stuck in the fixing means, the user must first open the cover and then rotate the lever or knob. However, there is a difficulty that the operation is complicated. Particularly in recent years, in order to increase the image forming speed, there is a tendency to increase the pressing force of the pressure roller (biasing force of the biasing means) with respect to the heat roller. This is because when the pressure is increased, the heat transfer efficiency is improved and the fixing speed is improved. Further, in a color image forming apparatus that fixes toner images of a plurality of colors on a recording material, it is necessary to fix toner images of a plurality of colors on the recording material at the same time (thus, a large amount of toner is applied to the recording material as compared with the case of monochrome). Since it needs to be fixed), the pressing force of the pressure roller also tends to increase. Therefore, the turning operation of the lever or the knob has become difficult.

An object of the present invention is to solve the above problems and to provide an image forming apparatus capable of easily removing a recording material jammed in a fixing means.

[0005]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention comprises a heat roller, and a pressure roller which is biased and pressed against the heat roller by a biasing means. In an image forming apparatus including a fixing unit having a cover, an openable and closable cover is provided on the surface of the device parallel to the axial direction of the pressure roller, and the cover is opened between the cover and the pressure roller. At this time, a separating mechanism for separating the pressure roller from the heat roller against the biasing force is provided. An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the separating mechanism has a cam, and the pressure roller is separated based on the rotation of the cam. Characterize.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the separating mechanism has a toggle mechanism at least in a part thereof.
An image forming apparatus according to a fourth aspect is the image forming apparatus according to the first, second, or third aspect, characterized in that at least a pair of links of the separating mechanism are configured to be capable of being disconnected.

[0006]

According to another aspect of the present invention, there is provided an image forming apparatus including a fixing unit having a heat roller and a pressure roller urged against the heat roller by the urging unit. A cover which can be opened and closed is provided on the surface of the device parallel to the axial direction of the pressure roller, and the pressure roller is provided between the cover and the pressure roller against the biasing force when the cover is opened. Since the separation mechanism for separating the heat roller from the heat roller is provided, the separation mechanism is operated and the pressure roller is separated from the heat roller by opening the cover in this image forming apparatus. Therefore, when the fixing unit is clogged with the recording material, the user can easily take out the recording material only by opening the cover. Further, since the cover is provided so as to be openable and closable on the surface of the device parallel to the axial direction of the pressure roller, the separation mechanism can be easily constructed. According to the image forming apparatus of claim 2, in the image forming apparatus of claim 1, the separating mechanism has a cam, and the pressure roller is separated based on the rotation of the cam. Therefore, the pressure roller can be separated from the heat roller simply by opening the cover with a small force. Therefore, it becomes unnecessary to increase the strength of the cover more than necessary. According to the image forming apparatus of claim 3, in the image forming apparatus of claim 1 or 2, since the separating mechanism has a toggle mechanism at least in a part thereof, only a small force is required to open the cover. Thus, the pressure roller can be separated from the heat roller. Therefore, it becomes unnecessary to increase the strength of the cover more than necessary. According to the image forming apparatus of the fourth aspect, in the image forming apparatus of the first, second or third aspect, at least a pair of links of the separating mechanism is configured to be disengageable, so that a fixing unit (for example, When the fixing unit) is configured to be attachable to and detachable from the apparatus body, the fixing unit can be easily attached to and detached from the apparatus body by releasing the connection state of the pair of links.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an internal structure of an embodiment of an image forming apparatus according to the present invention.

This image forming apparatus is an apparatus capable of forming a full-color image on both sides of a sheet (recording material), and is a case 10 and an image carrier which is detachably accommodated in each case 10. A unit 20, an exposure unit 30 as an exposing unit, and a developing device 40 as a developing unit.
And an intermediate transfer body unit 50 and a fixing unit 60 as fixing means.

A frame (not shown) of the apparatus main body is provided in the case 10, and each unit and the like are attached to this frame.

The image carrier unit 20 includes a photoconductor (image carrier) 21 having a photosensitive layer on its outer peripheral surface, and a corona discharge charger 22 as a charging means for uniformly charging the outer peripheral surface of the photoconductor 21. And the outer peripheral surface of the photoconductor 21 uniformly charged by the charger 22 is exposed to the exposure unit 3
A laser beam L from 0 is selectively exposed to form an electrostatic latent image, and a toner as a developer is applied to the electrostatic latent image by the developing device 40 to form a visible image (toner image). The toner image is primarily transferred to the intermediate transfer member (intermediate transfer belt) 51 of the intermediate transfer member unit 50 at the primary transfer portion T1 and further secondary transferred to the sheet to be transferred at the secondary transfer portion T2. ing.

Inside the case 10, there is a conveying path 16 for conveying a sheet on one side of which an image is formed by the secondary transfer section T2 toward a sheet discharging section (sheet discharging tray section) 15 on the upper surface of the case 10. A return path 17 is provided for returning the sheet conveyed by the conveying path 16 toward the sheet discharge section 15 to the secondary transfer section T2 so as to switch back the sheet and form an image on the other surface. At the bottom of the case 10, there are provided a paper feed tray 18 for stacking and holding a plurality of paper sheets, and a paper feed roller 19 for feeding the paper sheets one by one toward the secondary transfer portion T2.

The developing device 40 is a rotary developing device,
A plurality of developing device cartridges are detachably attached to the rotating body 41. In this embodiment, a yellow developing device cartridge 42Y, a magenta developing device cartridge 42M, a cyan developing device cartridge 42C, and a black developing device cartridge 42K.
Is provided (only the developing device cartridge 42Y for yellow is directly drawn in the figure), and the rotator main body 41
Rotates in the direction of the arrow at a pitch of 90 degrees, so that the developing roller 43 is selectively brought into contact with the photoconductor 21.
The surface of the photoconductor 21 can be selectively developed.

The exposure unit 30 irradiates the photoconductor 21 with the laser light L from an exposure window 31 made of plate glass or the like.

The intermediate transfer body unit 50 includes a unit frame (not shown), a driving roller 54, a driven roller 55, and a primary transfer roller 5 which are rotatably supported by the frame.
6, a guide roller 57 for stabilizing the state of the belt 51 at the primary transfer portion T1, and a tension roller 58
And the intermediate transfer belt 51 wound around these rollers and stretched, and the belt 51 is circularly driven in the direction of the arrow in the figure. Photoconductor 21 and primary transfer roller 56
The primary transfer portion T1 is formed between
The drive roller 54 and the secondary transfer roller 1 provided on the main body side
The secondary transfer portion T2 is formed at the pressure contact portion with 0b. The secondary transfer roller 10b can be brought into and out of contact with the drive roller 54 (and thus with respect to the intermediate transfer belt 51), and when it comes into contact with the drive roller 54, the secondary transfer portion T2 is formed.
Therefore, when forming a color image, toner images of a plurality of colors are superposed on the intermediate transfer belt 51 in a state where the secondary transfer roller 10b is separated from the intermediate transfer belt 51, and then a color image is formed. The secondary transfer roller 10b comes into contact with the intermediate transfer belt 51 and the paper is supplied to the abutting portion (secondary transfer portion T2), whereby the toner image is transferred onto the paper. The paper on which the toner image has been transferred is heated by a pair of heating rollers 61 and 62 of the fixing unit 60 (a heat roller 61 and a pressure roller 6 to be described later
The toner image is fixed by passing through the pressure contact portion 2) and is discharged toward the paper discharge tray portion 15.

The front surface of the apparatus case 10 (the pressure roller 6
A front cover 80 that can be opened and closed is provided in the axial direction of 2 (the plane of the device parallel to the plane of the paper of FIG. 1). The front cover 80 is rotatably attached to the apparatus main body by shafts 81, 81 (only one is shown).

FIG. 2 is a schematic side view showing the fixing unit 60, the front cover 80, and the separating mechanism 70. FIG. 3 is a perspective view showing the fixing unit 60. FIG. 4 is a fixing unit 6.
It is an exploded perspective view of 0. As shown in these figures, the fixing unit 60 includes a pair of left and right unit frames 63, 6
3 and the bearing members 61a, 6 on the frames 63, 63
Heat roller 61 rotatably supported via 1a (see FIG. 4), bearing members 62a and 62a (see FIG. 4) and pressure lever 6 with respect to the frames 63 and 63.
It has a pressure roller 62 rotatably and rotatably supported via 4, 4 and a fixing device cover 65.

As shown in FIGS. 3 and 4, the heat roller 6
1 is supported by the support hole 63a of the frame 63 via the bearing member 61a. The bearing member 62 a of the pressure roller 62 is gripped by the grip portion 64 a of the pressure lever 64. The pressure levers 64, 64 are the gripping parts 6 described above.
The pressure roller 62 is rotatably supported by a shaft 63b provided on a frame 63 while holding both ends of the pressure roller 62 by 4a. As shown in FIG. 2, a tension spring 66 (see FIG. 4) which is a biasing means is provided between the frame 63 and the pressure lever 64. Due to the tension of the tension spring 66, the pressure lever 64 is urged clockwise around the shaft 63b in FIG. 2, and the urging force presses the pressure roller 62 against the heat roller 61. The pressure contact force of the tension spring 66 is very strong, and one tension spring 66 can provide a pressure contact force of about 20 kg and two tension springs 66 can exert a pressure contact force of about 40 kg. In addition, in FIGS. 2 and 4, 6
3c is a spring hook portion on the frame 63 side, and 64b is a spring hook portion on the pressure lever 64 side. At one end of the pressure lever 64, a pin 64c capable of contacting the third link 73 of the separating mechanism 70 described later is provided.

As shown in FIG. 2, the separating mechanism 70 is provided between the front cover 80 and the pressure roller 62.
FIG. 5 is a schematic side view showing a state of the separating mechanism 70 and the fixing unit 60 when the front cover 80 is opened, and FIG. 6 is a perspective view of the same. As shown in these figures (mainly FIG. 5), the spacing mechanism 70 includes a first link 71, a second link 72, and a third link 73.

One end of the first link 71 is rotatably connected to the front cover 80 by a shaft 82, and the other end of the first link 71 is rotatably connected to a second link 72 by a shaft 71a. There is.

The second link 72 has the one end thereof on the shaft 7 side.
It is rotatably connected to the first link 71 at 1a, and the other end side is rotatably supported by a shaft 11 fixed to a frame (not shown) of the image forming apparatus main body. Therefore, the shaft 11 itself does not move even when the front cover 80 is opened.
Further, a cam portion (cam) 7 is provided on the other end side of the second link 72.
2a is formed.

The third link 73 is rotatably supported by the shaft 12 fixed to a frame (not shown) of the image forming apparatus main body. Therefore, the shaft 12 itself is the front cover 8
It does not move even if 0 is opened. At one end of the third link 73, the first link that contacts the cam portion 72a of the second link 72 is provided.
An abutting portion 73a is provided, and the second abutting portion 73 capable of abutting on the pin 64c of the pressure lever 64 described above is provided at the other end.
b is provided.

Therefore, the separating mechanism 70 as described above operates as follows. As shown in FIG. 2, the front cover 8
In the state where 0 is closed, the first to third links 71 to
73 is in a state of being compactly folded as shown (see FIG. 7). First of the third link 73
The contact portion 73a does not contact the cam portion 72a of the second link 72. In addition, the second contact portion 73 of the third link 73
b does not abut the pin 64c of the pressure lever 64 (lightly abuts even if it abuts). Therefore, the pressure lever 64 is biased by the tension spring 66 and is rotated clockwise as shown in FIG.
The pressing roller 62 is pressed against the heat roller 61 by the urging force of the tension spring 66.

When a paper jam occurs and the front cover 80 is opened by the user as shown in FIGS. 5 and 6,
From the state shown in FIG. 2, the first link 71 rotates counterclockwise around the shaft 82 and the second link 72 rotates clockwise around the fixed shaft 11. When the second link 72 rotates clockwise, the first contact portion 73a of the third link 73 is rotated.
Comes into contact with the cam portion 72a of the second link 72, whereby the third link 73 rotates clockwise about the fixed shaft 12. By the clockwise rotation of the third link 73, the second contact portion 73b of the third link 73 causes the pressing lever 64 to move.
The pressing lever 64 is rotated counterclockwise around the shaft 63b against the urging force of the tension spring 66 by pressing the pin 64c. As a result, the pressure roller 62 is separated from the heat roller 61 as shown in FIG. 5, and when the recording material is sandwiched between the pressure roller 62 and the heat roller 61, this can be easily performed. You will be able to remove it. Then, when the front cover 80 is closed, the state shown in FIG. 2 is restored.

As shown in FIG. 5, compared with the distance a between the shafts 81 and 82 in the front cover 80, the shaft 81 and the cover 8 are
The distance b to the knob portion 83 (see FIG. 6) of 0 is longer. Further, compared with the distance c between the shaft 11 and the cam portion 72a in the second link 72, the shaft 11 and the first link 7 are
The distance d to the connecting portion (shaft 71a) with 1 is longer. Therefore, the mechanism as described above constitutes a toggle mechanism, and the pressure roller 62 can be separated from the heat roller 61 by opening the front cover 80 with a small force. In addition, the cam portion 72a of the second link 72
The third link 73 itself also constitutes a toggle mechanism, and the pressure roller 62 can be separated from the heat roller 61 with a smaller force. As is apparent from FIG. 1, since the inner surface of the front cover 80 forms one side surface of the return path 17, by opening the front cover 80,
The paper jammed in the return path 17 can be easily removed.

FIGS. 8A and 8B show the first link 7 respectively.
It is a schematic diagram showing an example of the connecting structure of 1 and the 2nd link 72. In the connection structure shown in FIG. 7A, both side plate portions 71b, 71b of the first link 71 are made of flexible members (for example, synthetic resin).
This is a structure in which the above-mentioned shaft 71a is integrally formed inside. According to such a connection structure, both side plate portions 71
The connection between the first link 71 and the second link 72 can be released by bending b and 71b as shown by the phantom line and removing the shaft 71a from the second link 72. The connecting structure shown in FIG. 6B is a structure in which the first link 71 and the second link 72 are connected by a detachable shaft 71d.
Reference numeral 71e is an E ring (or C ring) that can be engaged with and disengaged from the shaft 71d. By removing the E ring 71e from the shaft 71d and removing the shaft 71d from the first link 71 and the second link 72, the first link 71 And the connection with the second link 72 can be released. The second link 72
The one end portion 72b is a stopper portion 71 of the first link 71.
By abutting on c, it is prevented from rotating further than the state shown in FIG. Further, such a connecting structure can be adopted in a connecting portion between the front cover 80 (this cover is also one of the links) and the first link 71, for example.

According to the image forming apparatus as described above, the following operational effects can be obtained. (A) The heat roller 61 and the pressure roller 62 that is urged and pressed against the heat roller 61 by the urging means 66.
In the image forming apparatus provided with the fixing unit 60 having, the openable and closable cover 80 is provided on the surface of the apparatus parallel to the axial direction of the pressure roller 62, and between the cover 80 and the pressure roller 62, Since the separating mechanism 70 that separates the pressure roller 62 from the heat roller 61 is provided against the urging force of the urging unit 66 when the cover 80 is opened, the separating mechanism 70 operates by opening the cover 80. The pressure roller 62 is separated from the heat roller 61. Therefore, when the fixing unit 60 is clogged with the recording material, the user can easily take out the recording material only by opening the cover 80. Also, the cover 80
Is provided on the surface of the apparatus parallel to the axial direction of the pressure roller 62 so as to be openable and closable, the separation mechanism 70 can be easily configured. (B) The separating mechanism 70 has the cam 72a, and the pressing roller 62 is separated based on the rotation of the cam 72a. Therefore, the pressing roller 62 is heated only by opening the cover 80 with a small force. It is possible to separate it from the roller 61. Therefore, it is not necessary to increase the strength of the cover 80 more than necessary. (C) Since the separating mechanism 70 has the toggle mechanism at least in a part thereof (the front cover 80, the first link 71, the second link 72, and the cam portion 72a and the third link 73), it requires a small force. The pressure roller 62 can be separated from the heat roller 61 only by opening the cover 80. Therefore, it is not necessary to increase the strength of the cover 80 more than necessary. (D) Since at least a pair of links (the first link 71 and the second link 72) of the separating mechanism 70 are configured to be capable of being disconnected, when the fixing unit 60 is attached to or detached from the apparatus main body, The fixing unit 60 can be easily attached to and detached from the apparatus main body by releasing the connection state of the link.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be appropriately made within the scope of the gist of the present invention.

[0028]

According to the image forming apparatus of any one of claims 1 to 4, when the fixing member is clogged with the recording material, the user can easily take out the recording material only by opening the cover. Further, according to the image forming apparatus of the second or third aspect, it is possible to separate the pressure roller from the heat roller only by opening the cover with a small force. Therefore, it becomes unnecessary to increase the strength of the cover more than necessary. According to the image forming apparatus of claim 4, when the fixing unit (for example, the fixing unit) is configured to be attachable to and detachable from the apparatus main body, the fixing unit is detached from the apparatus main body by releasing the connection state of the pair of links. Can be easily attached and detached.

[0029]

[Brief description of drawings]

FIG. 1 is a side view showing an internal structure of an embodiment of an image forming apparatus according to the present invention.

2 is a schematic side view showing a fixing unit 60, a front cover 80, and a separating mechanism 70. FIG.

FIG. 3 is a perspective view showing a fixing unit 60.

FIG. 4 is an exploded perspective view of the fixing unit 60.

FIG. 5 is a spacing mechanism 70 when the front cover 80 is opened.
6 is a schematic side view showing the state of the fixing unit 60. FIG.

FIG. 6 is a perspective view of the same.

FIG. 7 is a spacing mechanism 7 when the front cover 80 is closed.
6 is a perspective view showing the states of 0 and the fixing unit 60. FIG.

8A and 8B are a first link 71 and a second link, respectively.
Schematic which shows the example of the connection structure with the link 72.

[Explanation of symbols]

60 fixing unit (fixing means) 61 heat roller 62 pressure roller 66 Extension spring (biasing means) 70 Separation mechanism 72a cam 80 Front cover (cover)

Claims (4)

[Claims] 1. An image forming apparatus including a fixing unit having a heat roller and a pressure roller that is urged and pressed against the heat roller by an urging unit, wherein the fixing unit is parallel to the axial direction of the pressure roller. A cover that can be opened and closed is provided on the surface of the device, and a separating mechanism that separates the pressure roller from the heat roller against the biasing force when the cover is opened is provided between the cover and the pressure roller. An image forming apparatus characterized by being provided. 2. The image forming apparatus according to claim 1, wherein the separating mechanism has a cam, and the pressure roller is separated based on the rotation of the cam. 3. The image forming apparatus according to claim 1, wherein the separating mechanism has a toggle mechanism in at least a part thereof. 4. The image forming apparatus according to claim 1, wherein at least a pair of links of the separating mechanism are configured to be capable of being disconnected.