JP2001154526A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device in simple machine constitution for preventing fixing defects due to the operation error of a user and making the user able to freely cancel the press contact of a fixing roller. SOLUTION: A switching member 3 integrally provided with an operation lever 4 is movable to a 'copy position' for turning the fixing roller 1 to a press contact state, a 'JAM treating position' for turning the fixing roller 1 to a press contact cancellation state and a 'transport type position' for turning the fixing roller 1 to the press contact cancellation state. Further, when the switching member 3 is at the 'JAM treating position', an openable and closable carrying guide and the operation lever 4 interfere and the carrying guide is not completely closed. Further, when the switching member 3 is at the 'transport type position', the carrying guide is completely closed.

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 capable of switching between pressing and releasing of a fixing roller.

[0002]

2. Description of the Related Art A general fixing device mounted on an image forming apparatus such as a copying machine, a printer, a facsimile or the like has a configuration in which a nip having a predetermined width is formed by pressing a pressure roller against a heat roller. Here, since the surface of the pressure roller is generally formed of an elastic member such as silicon rubber, if the two rollers are left in pressure contact with each other for a long time, a part of the elastic member is deformed and cannot be restored. Will occur. Therefore, Japanese Patent Application Laid-Open No. 6-4000 discloses a fixing device in which a heat roller and a pressure roller are kept separated from each other at the time of product shipment, and a user can easily bring both rollers into a pressure contact state at the start of use. Has been proposed. This will be briefly described with reference to FIG. As shown in FIG. 4, the fixing device Z0 proposed in the above publication has a heat roller 51 and a pressure roller 52 which are arranged to face each other. A pressure releasing member 54 that is rotatable around the bearing 53 is provided outside the bearing 53 of the heat roller 51. An operation lever 54b and a cam portion 54a are formed integrally with the pressure release member 54. The pressure roller 52 is
It is elastically urged toward the heat roller 51 by a spring 56 via a bearing 55. When the fixing device Z0 is shipped, the pressure releasing member 54 is set at a position where the cam portion 54a pushes down the bearing 55 of the pressure roller 52 against the spring 56 as shown in FIG. . As a result, the pressure roller 52 is maintained in a state separated from the heat roller 51. At this time, the operation lever 54b of the pressure release member 54 is in a state of protruding from the frame 57. At the start of the use of the fixing device Z0, the user operates the operation lever 54b to cause the operation shown in FIG.
As shown in (b), the cam portion 54a is
The second bearing 55 comes off. As a result, the pressure roller 52 is biased by the spring 56 to generate the heat roller 51.
Is pressed against. At this time, the operation lever 54b of the pressure release member 54 is stored in the frame 57 and becomes inoperable. With the above-described configuration, the fixing device Z0 can maintain a state in which the heat roller and the pressure roller are separated from the time of product shipment to the start of use, and operate once the pressure roller is brought into the pressure contact state. It is stated that the lever is inoperable and fixing failure due to an operation error can be prevented.

[0003]

However, in the above-mentioned conventional fixing device Z0, once the heat roller 51 and the pressure roller 52 are brought into pressure contact with each other, the operation lever 54b of the pressure release member 54 is stored in the frame 57. As a result, there is a problem that the pressure of both rollers cannot be released, for example, at the time of re-transportation or JAM processing. Further, if another pressure releasing means is provided for the JAM processing, the number of parts increases, the structure becomes complicated, and the cost increases. Further, if the pressure releasing means for the JAM processing is easily provided, there is a possibility that a fixing error may occur due to an operation error such as performing an image forming process in a state where the pressure is released. The present invention has been made in view of the above circumstances, and an object of the present invention is to allow a user to freely release a pressure contact of a fixing roller while preventing a fixing failure due to a user's operation error. An object of the present invention is to realize an image forming apparatus with a simple mechanical configuration.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a pair of fixing rollers capable of switching between pressing and releasing, and a switching member for switching between pressing and releasing of the fixing roller. An image forming apparatus including an openable / closable cover for opening the vicinity of the fixing roller during a JAM process or the like, wherein the switching member is configured to: When the switching member is in the second position, the cover and the predetermined interference member interfere with each other when the switching member is in the second position. The image forming apparatus is characterized in that the cover is not completely closed. As a result, if the second position is set at the time of the JAM processing, it is possible to completely prevent a user's erroneous operation after the end of the JAM processing such as restarting copying while releasing the pressure contact of the fixing roller. . Further, the switching member is configured to be movable to a third position where the fixing roller is further released from the pressure contact state, and the cover is completely closed when the switching member is at the third position. Can also be configured. In this case, if the third position is, for example, the set position for transporting the main body, the pressing of the fixing roller is released to prevent the deformation of the roller and the like, and the cover is closed to hinder the work such as transportation. It can be done without. In addition, since the state of the fixing roller can be switched during copying, JAM processing, and transportation with a single switching member, cost reduction by reducing the number of parts and improvement in reliability by simplifying the mechanical configuration are expected. it can.

Further, if the switching member is configured to be able to move from the first position to the second position with a smaller force than moving the switching member from the second position to the third position, Can prevent the switching member from moving from the first position to the third position at once. As a result, for example, the JAM process is performed in a state where the user mistakenly sets the switching member to the third position,
The possibility of erroneous operations such as resuming image formation while closing the cover and releasing the pressure contact of the fixing roller is reduced. And a lock means for preventing the switching member from moving from the second position to the third position,
When the switching member is moved from the second position to the third position, it is necessary to release the lock means, so that image formation is resumed while the pressure contact of the fixing roller is released. Is less likely to be erroneously operated. Furthermore, if the switching member is configured to move from the first position to the second position in conjunction with the opening operation of the cover, the JAM processing operation becomes easier and more convenient. In addition, as the predetermined interference member, for example, the operation lever of the switching member can be used.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments and examples are examples embodying the present invention, and do not limit the technical scope of the present invention. Here, FIG. 1 is an explanatory view showing the configuration and operation near the fixing roller of the copying machine Z1 according to the embodiment of the present invention, FIG. 2 is a diagram schematically showing the internal configuration of the copying machine Z1, and FIG. FIG. 3 is an external perspective view of the copying machine Z1.

A copying machine Z1 according to the present embodiment is a small-sized copying machine as an example of an image forming apparatus according to the present invention, and as shown in FIG. And a sheet discharge section 22 for transfer paper formed in the middle of the section 21. First, the internal configuration of the image forming unit 1 of the copying machine Z1 will be briefly described with reference to FIG. At the lowermost part of the image forming section 21, a transfer paper tray 11 for storing transfer paper is provided. When the copying operation is started, the uppermost transfer paper on the transfer paper tray 11 is
The toner image formed on the photosensitive drum 14 by the developing device 18 and the like is conveyed by the paper feed roller 12 and the conveying roller pairs 13 and 13 and passes between the photosensitive drum 14 and the transfer roller 15. The toner image is transferred and further fixed on the fixing roller 1 (consisting of the heat roller 1a and the pressure roller 1b), and then discharged onto the discharge section 22 by the discharge roller 17. The copying machine Z1
The transport guide 20 (an example of a hatched portion in FIG. 2 and an example of a cover) is provided so that a transport path can be opened and a recovery operation can be easily performed when a paper jam (JAM) or the like occurs during transport of the transfer paper. It is configured to be openable and closable around a lower support point (not shown) toward the outside of the main body. The operation lever 4 (see FIG. 1) of the switching member 3 to be described later is
Operate with open.

Subsequently, referring to FIG. 1, the copying machine Z1
The configuration near the fixing roller 1 which is a characteristic part of the above will be described. The fixing roller 1 includes a heat roller 1a and a pressure roller 1b. The pressure roller 1b is elastically urged in the direction of the heat roller 1a by an elastic member (not shown). A switching member 3 integrally formed with an operation lever 4 is rotatably attached to an end of the support shaft 2 of the pressure roller 1b. Three notches 3a, 3b, and 3c are formed at the edge of the switching member 3. When the radius of the pressure roller 1b is R, the radii ra, rb, and rc at each notch are as follows. Is set. ra <R, rb> R, rc> R (1) In addition, in the three notches 3a, 3b, 3c, the operation lever 4 has the operation lever 4 shown in FIG. 1 (a), FIG. 1 (b), FIG.
It is provided at a position facing the heat roller 1a when it is at the position (c).

When the operation lever 4 is set to the "copy position" (corresponding to the first position) shown in FIG. 1A with the transport guide 20 (see FIG. 2) opened, the notch 3a is Although not facing the heat roller 1a, the cutout 3a does not come into contact with the heat roller 1a due to the relationship (1), so that the pressure roller 1b comes into pressure contact with the heat roller 1a. That is, during normal use, the operation lever 4 is set to the "copy position" shown in FIG.
When the operation lever 4 is set to the "JAM processing position" (corresponding to the second position) shown in FIG. 1B, the notch 3b faces the heat roller 1a.
The notch 3b is in a state of pressing the surface of the heat roller 1a. Thus, the state in which the pressure roller 1b is separated from the heat roller 1a is maintained, and the heat roller 1b
The work of removing the transfer paper jammed between the pressure roller 1a and the pressure roller 1b can be easily performed. Further, the operation lever 4
Is set to the “transport position” (corresponding to the third position) shown in FIG.
a, but due to the relationship (1) above, the “JA”
As in the case of the "M processing position", the notch 3c presses the end surface of the heat roller 1a. Thus, the state in which the pressure roller 1b is separated from the heat roller 1a is maintained, and deformation of the pressure roller during transportation or the like can be prevented.

As described above, the heat roller 1a and the pressure roller 1
In terms of separating the operating lever 4 from the position "b", the case where the operation lever 4 is set to the "JAM processing position" and the case where the operation lever 4 is set to the "transport position" are exactly the same. However, the two are completely different from each other in relation to the opening and closing of the transport guide 20 as follows. As shown in FIG.
Is set to the "JAM processing position", the operation lever 4 (an example of an interference member) projects greatly toward the outside of the main body, and the opened conveyance guide 2 is opened.
Even if it tries to close 0, it cannot interfere with the operation lever 4 and cannot be completely closed. That is, after the user sets the operation lever 4 to the “JAM processing position” and performs the JAM processing, the transport guide 20 is closed and copied in the state as it is (the heat roller 1a and the pressure roller 1b are separated). Can not be resumed. To resume copying, return the operation lever 4 to the “copy position”, and
Need to close. Therefore, it is possible to completely prevent a user's erroneous operation after the end of the JAM processing. On the other hand, when the operation lever 4 is set to the "transport position", the operation lever 4 enters the main body, so that the transport guide 20 can be closed as it is, which hinders the transportation operation. Will not come.

As described above, in the copying machine Z1 according to the present embodiment, when the operation lever 4 is set to the "JAM processing position" and the heat roller 1a and the pressure roller 1b are separated from each other, Since the transport guide 20 cannot be closed, it is possible to completely prevent a user's erroneous operation after the end of the JAM processing such as restarting copying while keeping the heat roller 1a and the pressure roller 1b separated. Further, since the state of the fixing roller 1 can be switched by one switching member 3 at the time of copy processing, JAM processing, and transportation, the cost can be reduced by reducing the number of parts, and the reliability can be improved by simplifying the mechanical configuration. Can be expected.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When a user performs a JAM process with the operation lever 4 set to the "transport position" by mistake, the transport guide 20 can be closed without returning the operation lever 4 to the "copy position". Yes, heat roller 1a and pressure roller 1b
There is a possibility that an erroneous operation such as restarting the copy while keeping the distance between them may be performed. Therefore, it is desirable to provide a mechanism for preventing a user from setting the operation lever 4 to the “transport position” by mistake. For example, the torque required to move the operation lever 4 from the “JAM processing position” to the “transport position” is larger than the torque required to move the operation lever 4 from the “copy position” to the “JAM processing position”. For example, it is less likely that the operation lever 4 is moved from the "copy position" to the "transport position" at a stretch due to excessive momentum. In this case, specifically, it is conceivable to make the radius of the projection between the notches 3b and 3c larger than the radius of the projection between the notches 3a and 3b. Alternatively, a lock means for preventing the operation lever 4 from moving from the "JAM processing position" to the "transport position" is provided, and when the operation lever 4 is moved from the "JAM processing position" to the "transport position". If the lock means needs to be released, the malfunction preventing effect is further enhanced.

If the operation lever 4 is moved from the "copy position" to the "JAM processing position" in conjunction with the opening operation of the transport guide 20, the JAM processing operation becomes easier and more convenient. . In the above embodiment,
When the operation lever 4 is set to the “JAM processing position” or the “transport position”, the heat roller 1a is moved to the pressure roller 1b.
Are completely separated from each other. However, it is not always necessary to completely separate both rollers, and it is sufficient that the pressure contact can be released to such an extent that a problem such as deformation of the pressure roller 1b can be prevented. In the above-described embodiment, the operation lever 4 interferes with the conveyance guide 20 at the “JAM processing position” to prevent the closing operation of the conveyance guide 20. However, the operation lever 4 does not always interfere with the operation lever 4. Needless to say, the configuration may be such that other parts interfere.

[0014]

As described above, according to the present invention, the pressure welding /
A pair of fixing rollers capable of switching the press-contact release, a switching member for switching the press-contact / release of the fix roller, and an openable / closable cover for opening the vicinity of the fix roller during a JAM process or the like. In the image forming apparatus, the switching member is configured to be movable between a first position in which the fixing roller is in the pressed state and a second position in which the fixing roller is in the released state. The image forming apparatus is configured such that when the switching member is at the second position, the cover interferes with a predetermined interference member so that the cover is not completely closed. , The second position is set to JA.
If the set position is set at the time of the M processing, it is possible to completely prevent a user's erroneous operation after the end of the JAM processing such as restarting copying while releasing the pressure contact of the fixing roller. Further, the switching member is configured to be movable to a third position where the fixing roller is further released from the pressure contact state, and the cover is completely closed when the switching member is at the third position. Can also be configured. in this case,
If the third position is, for example, the set position for transporting the main body, the pressing operation of the fixing roller is released to prevent the deformation and the like of the roller, and the cover is closed to perform the operation such as transportation without any trouble. Can be. During copy processing, JAM
Since the switching of the state of the fixing roller at the time of processing and transportation can be performed by one switching member, cost reduction by reducing the number of parts and improvement in reliability by simplifying the mechanical configuration can be expected.

Further, if the switching member can be moved from the first position to the second position with a smaller force than the movement of the switching member from the second position to the third position, the user Can prevent the switching member from moving from the first position to the third position at once. As a result, for example, the JAM process is performed in a state where the user mistakenly sets the switching member to the third position,
The possibility of erroneous operations such as resuming image formation while closing the cover and releasing the pressure contact of the fixing roller is reduced. And a lock means for preventing the switching member from moving from the second position to the third position,
When the switching member is moved from the second position to the third position, it is necessary to release the lock means, so that image formation is resumed while the pressure contact of the fixing roller is released. Is less likely to be erroneously operated. Furthermore, if the switching member is configured to move from the first position to the second position in conjunction with the opening operation of the cover, the JAM processing operation becomes easier and more convenient.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration and operation near a fixing roller of a copying machine Z1 according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing an internal configuration of the copying machine Z1.

FIG. 3 is an external perspective view of the copying machine Z1.

FIG. 4 is a diagram showing a schematic configuration of a fixing device Z0 according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fixing roller 1a ... Heat roller 1b ... Pressure roller 3 ... Switching member 3a, 3b, 3c ... Notch part 4 ... Operation lever 20 ... Transport guide (an example of a cover)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsuro Tomoe 1-2-2, Tamazo, Chuo-ku, Osaka-shi Mita Kogyo Co., Ltd. (72) Inventor Takakazu Morita 1-2-28 Tamazo, Chuo-ku, Osaka Mita Kogyo Inside (72) Inventor Takashi Furuya Mita Kogyo Co., Ltd. 1-2-2, Tamazo, Chuo-ku, Osaka-shi Inside (72) Inventor Tomohide Hozono 2-2-2, Tamazo, Chuo-ku, Osaka Mita Kogyo, Ltd. F-term (reference) 2H033 AA02 AA29 AA37 BA06 BB01 BB28 BB35 BB38 2H071 AA08 AA20 AA42 DA12 DA23 EA01 2H072 AA02 AA16 EA11 EA16 3F048 AA02 AA04 AB01 BA14 BD02 EA11 3F012 A0204

Claims (6)

[Claims] 1. A pair of fixing rollers capable of switching between pressing / releasing, a switching member for switching between pressing / releasing of the fixing roller, and a member for opening the vicinity of the fixing roller during JAM processing or the like. In an image forming apparatus having an openable and closable cover, the switching member is provided between a first position for bringing the fixing roller into a pressed state and a second position for bringing the fixing roller into a released state. And when the switching member is in the second position, the cover interferes with a predetermined interference member so that the cover is not completely closed. An image forming apparatus comprising: 2. The switching member is further configured to be movable to a third position where the fixing roller is released from the pressure contact state, and when the switching member is in the third position, the cover is completely closed. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to be closed. 3. The switching member is moved from the second position to a third position.
3. The device according to claim 1, wherein the first position can be moved from the first position to the second position with a smaller force than the first position.
The image forming apparatus as described in the above. 4. A third position of the switching member from the second position.
4. A lock means for preventing movement to a position, wherein the lock means must be released when the switching member is moved from the second position to the third position. An image forming apparatus according to any one of the above. 5. The image forming apparatus according to claim 1, wherein said switching member is configured to move from said first position to said second position in conjunction with the opening operation of said cover. apparatus. 6. The image forming apparatus according to claim 1, wherein said predetermined interference member is an operation lever of said switching member.