JPH1074015A - Fixing device in image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simply structured fixing device in an image forming device, capable of preventing the occurrence of the catching of a transfer paper under a fixing roller and a pressing roller and a jamming and surely and quickly detecting the occurrence, for evading trouble. SOLUTION: The turning center shaft 3 of a separating pawl 2 is supported by a guiding long groove 1 formed to pass through on a device main body side. When a paper sheet is caught or jammed, the separating pawl 2 is moved on the circumference concentric with the outer periphery of the fixing roller 10, along the guiding long groove 1. Thus, a detecting sensor 8 is turned on/off with a lever member 7 abutted on the turning center shaft 3, to be engaged therewith, so that the occurrence of the trouble is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device in an image forming apparatus, such as a copying machine or a printer, for transferring toner to transfer paper using a fixing roller and a pressure roller. And quickly detect
The present invention relates to a fixing device in an image forming apparatus for preventing occurrence of a trouble in advance.

[0002]

2. Description of the Related Art Transfer paper on which toner has been transferred from a photosensitive drum side is thermally fixed by a fixing device. However, the transfer paper is often entangled with the heated fixing roller when it is fixed by the fixing device, and often causes troubles such as jams. Therefore, various techniques for solving the above-mentioned problems have been disclosed. For example, JP-A-7-129023, JP-A-63-58268, and JP-A-59-214065 can be mentioned.

[0003] An "image forming apparatus" disclosed in Japanese Patent Application Laid-Open No. 7-129023 discloses a method in which a density difference is provided on the surface of a fixing roller, and a change in the density of the fixing roller when the transfer paper is wound around the fixing roller is detected. Is detected.

In a fixing device disclosed in Japanese Utility Model Laid-Open Publication No. 63-58268, a tip of a peeling claw (corresponding to the separation claw) is brought into contact with the outer periphery of a fixing roller so as to be able to come and go.
The peeling claw and the fixing roller are electrically closed loop, and the open state of the closed loop is detected to detect the winding of the transfer paper.

Japanese Patent Laid-Open Publication No. Sho 59-214065 discloses a "fixing apparatus for a copying machine" in which one end of a paper ejection detection lever is rotatably provided at an appropriate position on a support member of a peeling claw. The end is characterized in that it enters between the light emitting element and the light receiving element when the peeling claw is set at a predetermined position, and detects whether the peeling claw is correctly set.

FIG. 9 shows a schematic structure of a conventional fixing device generally used. That is, the transfer paper 13 sandwiched between the fixing roller 10 having the built-in heater 11 and the pressing roller 12 pressed by the same is heat-fixed to the transferred toner. Is guided by the lower guide plate 15 and is guided to the paper discharge roller pair 17, 18 side to be discharged.

[0007] As shown in the figure, a separating claw 2a is rotatably disposed on the outer periphery of the fixing roller 10 on the side of the fixing roller 10 so as to support and engage the leading end so as to be able to come and go. Further, a detection sensor 19 is disposed on the side of the paper discharge roller pair 17, 18.
As shown in the figure, the transfer paper 13 is prevented from being wound around the fixing roller 10 and the jam 20 is prevented in principle by the presence of the separation claw 2a, and when the jam 20 occurs, the detection sensor 1 is used.
9, the leading end of the jam 20 is detected, and its occurrence is detected.

[0008]

The above-mentioned known techniques have their respective features, but have the following problems.
Generally, the fixing roller forms a surface layer of silicon rubber, and it is actually quite difficult to form a pattern having a density difference on the surface layer, and the cost is high. Further, it is difficult to accurately detect a change in the pattern, and the pattern becomes large and expensive.

Also, it is difficult to ensure reliability. Further, when the transfer paper is a two-sided copy, if the one side of the transfer paper is disposed in contact with the pattern of the fixing roller, the transferred image and the pattern of the fixing roller interfere with each other and accurate detection is not performed. is there. Further, even in the case of single-sided copying, there is a problem that if toner or the like adheres to a portion of the transfer paper that is in contact with the fixing roller side, the pattern changes due to the toner, and an accurate pattern change cannot be detected.

Japanese Unexamined Utility Model Publication No. 63-58268 discloses detecting a paper jam or entanglement of paper by opening a closed loop as described above. However, since the degree of freedom of the peeling claw is limited in the rotating direction. In some cases, the closed loop is not released depending on how the transfer paper is wound. Further, when a jam occurs, there is a problem that the closed loop is not released following the jam.

[0011] Also. Japanese Unexamined Patent Publication No. 59-214065 has an object to prevent the setting of the peeling claw after the paper jam is treated as described above, and no special measures are taken with respect to the prevention of the paper jam and the detection of the occurrence of the jam. .

In the case of the fixing device generally used in the related art shown in FIG. 9, since the detection sensor 19 is disposed on the discharge roller pair 17 and 18 sides, the detection sensor 19 moves to the fixing roller 10 side as shown in the figure. Of the transfer paper 13 cannot be detected. Also, the jam 20 cannot be detected until the tip of the jam 20 reaches the position of the detection sensor 19.

SUMMARY OF THE INVENTION The present invention solves the above problems, and prevents paper jams, paper jams, and jams in a fixing device, and reliably and quickly detects the occurrence to reduce troubles in the fixing device. It is another object of the present invention to provide a fixing device in an image forming apparatus which can be implemented at relatively low cost and can improve reliability.

[0014]

According to the present invention, in order to achieve the above object, the leading end portion is detachably engaged with the outer periphery of a fixing roller and a pressure rope for thermally fixing toner transferred to a transfer sheet. A fixing claw rotatably supported, and a spring or the like for urging the tip of the separation claw to press against the outer periphery of the roller. Detecting means for providing a guide elongated groove formed along a circumference concentric with the outer periphery of the roller and for guiding and supporting a rotation center axis of the separation claw, and detecting movement of the rotation center axis along the guide elongated groove; Constitutes a fixing device in the image forming apparatus provided with.

According to a second aspect of the present invention, in the fixing device of the image forming apparatus, a plurality of the separation claws are provided along an axial direction of the roller, and are supported by a single rotation center shaft. Both ends of the rotation center shaft are supported by the guide groove.

According to a third aspect of the present invention, in the fixing device of the image forming apparatus, a plurality of the separation claws are provided along an axial direction of the roller, and each of the separation claws is supported by a unique rotation center shaft. Each end of each of the pivot shafts is supported by the guide slot.

According to a fourth aspect of the present invention, in the fixing device of the image forming apparatus, one or a plurality of the detecting units are provided.

According to a fifth aspect of the present invention, in the fixing device of the image forming apparatus, the separating claw and the detecting unit are arranged on both the fixing roller and the pressure roller.

When the transfer paper gets caught in the fixing roller or the pressure roller or a jam occurs, the separation claw is pressed by the transfer paper. In the related art, the separation claw only rotates when the transfer paper is pressed, but in the present invention, the separation claw moves along the guide long groove by this pressing force. This movement responds sensitively to the occurrence of a small trouble of the transfer paper. The detecting means of the present invention is configured and arranged to detect the movement of the separation claw, so that when a trouble occurs, a detection signal is immediately issued and a measure is taken.

On the other hand, the separation claws are arranged at a plurality of positions, are supported on a single or respective rotation center shafts, and are formed so that the movement of the separation claws can be reliably detected. Also, even if the detection means is arranged at one place, the movement of the separation claw can be accurately detected, so that
The device can be implemented relatively cheaply. Further, by applying the present invention not only to the fixing roller but also to the pressure roller side, more reliable detection of troubles such as entangling of transfer paper is performed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fixing device in an image forming apparatus according to the present invention will be described below in detail with reference to the drawings.
First, a fixing device of the present invention in which a separation claw 2 is engaged with a fixing roller 10 will be described with reference to FIG. A pressure roller 12 is pressed against the fixing roller 10 to transfer the transfer paper 1 conveyed.
3 and heat fixing is performed. A guide slot 1 is formed through an unillustrated apparatus main body that pivotally supports the fixing roller 10, the pressure roller 12, and the like.

On the other hand, the separation claw 2 is composed of a lever-shaped member whose intermediate portion is supported by the rotation center shaft 3, and one end of the separation claw extends toward and closes to the fixing roller 10 so as to abut and engage therewith. It is placed in a position where it can be done. One end of a spring 4 is engaged with the other end of the separation claw 2, and the other end of the spring 4 is connected to a support shaft 5 fixed to the apparatus main body. Note that the spring 4 urges the tip of one side of the separation claw 2 to press the fixing roller 10.

As shown in FIGS. 1 and 2, the guide slot 1 is formed on a circumference concentric with the outer periphery of the fixing roller 10 by an appropriate arc length (radius R, shown in FIG. 2). The rotation center shaft 3 is supported by the guide slot 1 and movably supported along the arc of the guide slot 1. As described above, since the guide slot 1 is concentric with the outer periphery of the fixing roller 10, even if the rotation center shaft 3 moves along the guide slot 1, the separation claw 2
Of the fixing roller 1 in the same manner as before the movement.
0 and abuts on the outer circumference.

As shown in FIGS. 1 and 2, a support shaft 6 pivotally supported at a predetermined position of the apparatus main body is connected to an intermediate portion of a lever member 7. One end of the lever member 7 is disposed in contact with the outer periphery of the rotation center shaft 3 of the separation claw 2, and the other end surface is disposed so as to be capable of engaging and disengaging with the detection sensor 8 of the detection means. The detection sensor 8 detects O when the lever member 7 is engaged.
FF is turned on at the time of disengagement to generate a detection signal,
For example, the operation of the fixing device is stopped. As shown in FIG. 5, a pressure spring 9 is provided on the lever member 7 and urges one end of the lever member 7 so as to press against the outer periphery of the rotation center shaft 3.

The upper guide plate 14 and the lower guide plate 15 are opposed to each other with a gap through which the transfer paper 13 can pass.
And a discharge port 16 is formed at the other end. In the vicinity of the paper discharge port 16, paper discharge roller pairs 17, 18 are arranged in contact with each other.

As shown in FIG. 2, when the separation claw 2 is pressed at its tip A, the rotation center axis 3 moves along the guide slot 1 as shown by the dotted line, and the tip A is fixed to the fixing roller 10. Along the outer periphery of A to the position of A '. Since one end side of the lever member 7 is pressed against the rotation center shaft 3 by the pressing spring 9 (FIG. 5), the movement of the rotation center shaft 3 causes the lever member 7 to move.
Rotates around the support shaft 6, and moves in a direction in which the other end is separated from the detection sensor 8. Therefore, the detection sensor 8 is turned on and a detection signal is issued.

As shown in FIG. 3, when the transfer paper 13 transferred by the fixing roller 10 and the pressing roller 12 is wound around the outer periphery of the fixing roller 10, the leading end of the transfer paper 13 causes the separation claw 2 to point A in FIG. Is pressed. Accordingly, the separation claw 2 moves as shown in FIG. 2, and the detection signal is sent from the detection sensor 8 as described above. As shown in FIG. 4, when the jam 20 occurs, the separation claw 2 moves as in the case of FIG. 3, and a detection signal is generated.

The movement of the separation claw 2 shown in FIGS. 3 and 4 is performed immediately when a trouble occurs on the transfer paper 13, and the operation is not delayed in principle. That is, the guide long groove 1 is formed concentrically with the fixing roller 10 so that the rotation center shaft 3 of the separation claw 2 can smoothly move inside the guide long groove 1. Therefore, a detection signal is issued from the detection sensor 8 side at the same time when the trouble of the transfer paper 13 occurs. Therefore, unlike the related art, there is no delay in finding a trouble or inaccurate detection accuracy. Further, the separation claw 2 and the fixing roller 1
0 when the transfer paper 13 is caught between
Tries to rotate about the rotation center axis 3, but also in this case, since the rotation center axis moves along the guide long groove 1, the detection by the detection sensor 8 is performed in the same manner as described above.

FIG. 5 shows a state in which a plurality of separation claws 2 arranged along the axial direction of the fixing roller 10 are supported by a single rotation center shaft 3. In this example, both ends of the single rotation center shaft 3 are supported by the guide slots 1, 1, and the lever member 7,
7 are arranged at both ends. In this embodiment, the detection accuracy of the movement of the rotation center shaft 3 can be improved by engaging the detection sensors 8 with the respective lever members 7.

FIG. 6 shows an embodiment of the present invention when a single detection sensor 8 is used. Separating claws 2 similar to those shown in FIG. 5 are attached to the single rotation center shaft 3, respectively, but are omitted in the drawing. In this example, the lever member 7a
Is an integral structure, and the detection sensor 8 is provided only on one end side.
The lever 21 is formed to engage with the lever 21. With the above structure, the cost can be reduced by the small number of the detection sensors 8. Although the movement of the lever member 7a during the movement of the rotation center shaft 3 becomes less smooth than that in FIG. 5, the movement of the separation claw 2 is detected in substantially the same manner as in FIG.

FIG. 7 shows an embodiment in which both ends of the rotation center shaft 3 unique to each of the plurality of separation claws 2 are supported by the guide elongated grooves 1, 1. In this embodiment, the lever member 7 is used.
b has an integral structure, and has a contact lever portion 22 that is in contact with the outer periphery of the rotation center shaft 3, but a single lever portion 21 b is formed to protrude in a direction opposite to the contact lever portion 22. , Engage with a single detection sensor 8. In this case,
Since the separation claws 2 are supported by the guide slots 1, respectively, and the contact lever portions 22 of the lever members 7b are in contact with the respective rotation center shafts 3, fine changes in the separation claws 2 are detected. High-precision detection is performed.

FIG. 8 shows an embodiment in which the components according to the present invention are arranged on both the fixing roller 10 and the pressure roller 12. The transfer paper 13 may not only be wrapped around the fixing roller 10 but also wrapped around the pressure roller 12, but according to the present embodiment, the trouble is surely detected even in this case. As shown in FIG. 8, a return spring 23 is disposed on the lever member 7 on the side of the pressure roller 12 to facilitate the movement of the separation claw 2 to the return side.

[0033]

【The invention's effect】

1) According to the fixing device of the first aspect of the present invention, when a trouble such as entangling of the transfer paper or a jam occurs, the separation claw moves immediately in response thereto, and the detecting unit can be activated. Therefore, it is possible to reliably grasp the trouble and quickly respond. Therefore, paper damage due to paper entanglement and jam can be prevented, the reliability of the apparatus can be improved, and the operation rate of the apparatus can be improved by reducing troubles.

2) According to the fixing device of the second aspect of the present invention, since a plurality of separation claws are connected by a single rotation center shaft, the structure can be made compact, and the plurality of separation members can be separated. The movement of the claw is quickly transmitted to the detection sensor by the common rotation center axis.

3) According to the fixing device of the third aspect of the present invention, since the plurality of separation claws are supported by the respective rotation center shafts and guide grooves, minute movement of the separation claws can be accurately performed. Ascertained, high-precision detection is performed.

4) According to the fixing device of the fourth aspect of the present invention, a single detecting means is used, and the cost can be surely reduced.

5) According to the fixing device of the fifth aspect of the present invention, the fixing roller and the pressing roller are provided with the present invention such as a separation claw on both the fixing roller and the pressing roller. All the troubles at the time of fixing in the periphery are prevented, and the reliability can be further improved.

[Brief description of the drawings]

FIG. 1 is a side view showing the overall structure of the present invention.

FIG. 2 is a partial side view illustrating a moving structure of a separation claw according to the present invention.

FIG. 3 is a partial side view showing the operation of the main part when the transfer paper is wound in the present invention.

FIG. 4 is a partial side view showing a response of the present invention when a jam occurs.

FIG. 5 is a perspective view showing an example of the present invention using a single rotation center axis.

FIG. 6 is a side view showing another example of the present invention using only a single detecting means.

FIG. 7 is a perspective view showing a state in which a unique rotation center axis is provided for each of a plurality of separation claws.

FIG. 8 is a side view showing a case where the present invention is applied to a fixing roller and a pressure roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Guide long groove 2 Separation claw 3 Rotation center axis 4 Spring 5 Support shaft 6 Support shaft 7 Lever member 7a Lever member 7b Lever member 8 Detection sensor 9 Pressure spring 10 Fixing roller 11 Heater 12 Pressure roller 13 Transfer paper 14 Above Guide plate 15 Lower guide plate 16 Discharge port 17 Discharge roller pair 18 Discharge roller pair 19 Detection sensor 20 Jam 21 Lever 21b Lever 22 Contact lever 23 Return spring

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[Procedure amendment]

[Submission date] November 7, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a side view showing the overall structure of the present invention.

FIG. 2 is a partial side view illustrating a moving structure of a separation claw according to the present invention.

FIG. 3 is a partial side view showing the operation of the main part when the transfer paper is wound in the present invention.

FIG. 4 is a partial side view showing a response of the present invention when a jam occurs.

FIG. 5 is a perspective view showing an example of the present invention using a single rotation center axis.

FIG. 6 is a side view showing another example of the present invention using only a single detecting means.

FIG. 7 is a perspective view showing a state in which a unique rotation center axis is provided for each of a plurality of separation claws.

FIG. 8 is a side view showing a case where the present invention is applied to a fixing roller and a pressure roller.

FIG. 9 is a side view showing a schematic structure of a conventional fixing device.

[Description of Signs] 1 Guide long groove 2 Separator claw 3 Rotation center axis 4 Spring 5 Support shaft 6 Support shaft 7 Lever member 7a Lever member 7b Lever member 8 Detection sensor 9 Pressure spring 10 Fixing roller 11 Heater 12 Pressure roller 13 Transfer Paper 14 Upper Guide Plate 15 Lower Guide Plate 16 Discharge Port 17 Discharge Roller Pair 18 Discharge Roller Pair 19 Detection Sensor 20 Jam 21 Lever 21b Lever 22 Contact Lever 23 Return Spring

Claims (5)

[Claims] A separating claw rotatably supported so that a leading end of the fixing roller can be brought into contact with and separated from the outer periphery of a fixing roller for thermally fixing the toner transferred to the transfer paper; A fixing device including a spring for urging the leading end of the fixing device against the outer periphery of the roller, wherein the fixing device has a main body side formed along a circumference concentric with the outer periphery of the roller. A fixing device in an image forming apparatus, comprising: a guide slot that guides and supports a rotation center axis of a separation claw; and a detection unit that detects movement of the rotation center axis along the guide slot. 2. A plurality of separation pawls are provided along the axial direction of the roller, are supported by a single rotation center shaft, and both ends of the rotation center shaft are the guide elongated grooves. The fixing device according to claim 1, wherein the fixing device is supported by: 3. A plurality of the separation claws are provided along the axial direction of the roller, and the separation claws are supported by respective unique rotation center shafts, and both ends of each of the rotation center shafts are The fixing device according to claim 1, wherein the fixing device is supported by the guide groove. 4. The fixing device according to claim 1, wherein one or a plurality of the detection units are provided. 5. A fixing device in an image forming apparatus, wherein the separation claw and the detection unit are disposed on both the fixing roller and the pressure roller.