JPH02266381A - Fixing device - Google Patents

Abstract

PURPOSE:To use a device on such condition or environment that allows shift to be increased and to detect abnormal shift even when a normal shift detecting means does not normally work by providing an abnormal shift detecting means, which detects the abnormal shift of a belt, besides the normal shift detecting means which detects the normal shift of the heat-resistant endless belt. CONSTITUTION:Besides the normal shift detecting means 48 which detects the normal shift of the heat-resistant endless belt 23, the abnormal shift detecting means 1 which detects the abnormal shift of the belt 23 is provided. Namely, when an image forming device containing a fixing device is installed at an extremely uneven place and the heat-resistant endless belt 23 keeps unidirectionally shifting, it is judged to be jammed by a microcomputer based on a signal from a photointerrupter 6 through an abnormal shift detecting lever 1, a pinion 2, and a rack 3, etc., and the action of a main body is stopped. Consequently, since a main body motor is stopped, the heat-resistant endless belt 23 is not completely shifted and is stopped, and thereby occurring no rupture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device that fixes a toner image on a recording material by heating and melting it via a heat-resistant endless belt.

[Background of the Invention] In a fixing device that fixes a toner image on a recording material by heating and melting it via a heat-resistant thin belt, the belt is fixed by controlling the cylindricity and surface properties of the roller, as well as the parallelism of the roller surface. , due to uneven flatness, etc., the belt shifts in the width direction.

Therefore, a means is required to suppress movement of the belt in the width direction within a certain range. For example, using a crown roller, the widthwise movement of an endless belt,
That is, an effective method is to correct the belt misalignment by mechanically, optically, or electrically detecting the misalignment and moving at least one of the plurality of rollers.

[Problems to be Solved by the Invention] However, in the above example, an image forming apparatus including a fixing device using a heat-resistant endless belt, for example,
When installed on extremely uneven ground or used in an environment such as a vehicle that is subject to strong vibrations, the frame, side plates, bottom plate, stay, etc. of the image forming device, etc. and the fixing device may become twisted or twisted. The specified distance between the rollers, parallelism,
Sometimes flatness cannot be maintained. In such a case, there is a problem in that the above-mentioned deviation prevention means cannot prevent deviation, and the endless belt shifts in one direction, resulting in damage to the ends of the endless belt.

In addition, when detecting belt deviation and controlling the deviation, the sensor that detects the deviation may falsely detect it due to temperature rise due to fixing heat or other reasons, or the microcomputer may malfunction due to noise etc. It may become impossible to detect deviation, or the detection result may not be fed back properly, causing the endless belt to shift in one direction, causing damage to the ends of the endless belt. There was a point.

The present invention aims to solve the above problems. That is, an object of the present invention is to provide a fixing device that can detect abnormal deviation of a heat-resistant endless belt and prevent damage to the belt.

[m! ! Means for Solving the Problem] In order to achieve the above object, the present invention provides a fixing device that fixes a toner image on a recording material by heating it via a heat-resistant endless belt, which detects the normal deviation of the belt. In addition to the normal deviation detection means for detecting abnormal deviation of the belt, an abnormal deviation detection means for detecting abnormal deviation of the belt is provided.

[Function] According to the present invention, the abnormal deviation detection means is provided in addition to the normal deviation detection means for detecting the normal deviation of the heat-resistant endless belt, so that it can be used in situations or environments that increase deviation. Even if the normal deviation detecting means does not operate normally, abnormal deviation can be detected, so damage to the endless belt can be prevented.

[Embodiment] Figures 1 to 5 show the first embodiment of the present invention, and the sixth embodiment shows the first embodiment of the present invention.
The figure also shows the second embodiment.

2 shows a state where the bearing 35 on the back side of the driven roller 24 is pushed down, and FIG. 3 shows a state where the bearing 35 of the driven roller 24 is pushed up by the spring 37.

That is, as shown in FIGS. 342 and 3, the bearing 3 of the driven roller 24 paired with the driving roller 25
5 is supported by the side plate 46 so as to be slidable in the vertical direction, and rotatably supports one end of the driven roller 24, and the other end of the driven roller 24 is supported by a bearing (not shown) provided on the side plate 47.
is rotatably supported.

A fixing member 36 attached to the front north side plate 46 supports one end of a spring 37 for pushing up the bearing 35, and the other end of the spring 37 presses the lower end of the bearing 35. The spring clutch 38 includes an input hub (not shown), a coil spring (not shown) having a control claw (not shown), a control collar 40a provided to hold the control claw, and an output hub 41. configured, the control collar 408 is a second
As shown in FIG. 3 and FIG. 3, when the engaging pawl 40b or 40c is engaged with the lever pawl 44 and stopped, the power of the input hub is not transmitted to the output hub 41, and the lever pawl 44 is stopped.
4 is separated from the engaging claw 40b or 40c, the control collar 40a becomes rotatable, and power is transmitted from the input hub to the output hub 41. Rotational force is constantly transmitted to the input hub in the direction of arrow B in FIG. 2 via a gear (not shown).

A cam 39 having a different radius depending on the angle is fixed to the output hub 41 so as to rotate together with the cam 39. As shown in FIG. 2, when the engaging claw 40b and the lever claw 44 are engaged, the lower radius of the cam 39 is at its maximum, and as shown in FIG. When the pawl 44 is engaged, the lower radius of the cam 39 is at its minimum, and in other positions there is a smooth connection therebetween.

Therefore, when the engagement claw 40b is engaged with the lever claw 44, the maximum radius portion of the cam 39 pushes the bearing 35 downward, and when the engagement claw 40c is engaged with the lever claw 44, the bearing 35 is pushed down by the spring. 37 pushes it upward.

Further, the lever 43 is rotatably supported by a support shaft 42 implanted in a side plate 46, and has a lever pawl 44 formed at its other end, and this other end is connected to an operating rod of a solenoid 45.

The solenoid 45 is turned on for a predetermined period of time in response to signals from sensors 48 and 49, which will be described later.

The sensors 48 and 49 detect that the heat-resistant endless belt 23 has moved to the back or front of a predetermined position. The output signals of the sensors 48 and 49 are sent to the microcomputer, and the solenoid 45 is turned on according to a predetermined sequence.

In addition, in Fig. 2 and 's3, 21 is a heating element;
2 is a pressure roller, and 32 and 34 are guide plates.

Figure 4 shows the driven roller 24 and drive roller 2 seen from the paper feed side.
5 shows the positional relationship of 5.

As mentioned above, when the minimum radius part of the cam 39 shown in FIG. 3 faces the bearing 35, the end of the driven roller 24 is pushed up by the spring 37, and as shown in FIG. It will be in the upper right position. At this time, the heat-resistant endless belt 23 moves to the right (inner side) in FIG. 4. As described above, when the bearing 35 is pushed down by the cam 39, the heat-resistant endless belt 23 can be moved to the left (front) direction.

That is, by moving the driven roller 24 through a cam mechanism or the like based on the output signals of the sensors 4B and 49, the heat-resistant endless belt 23 can normally be run stably within a certain range.

By the way, when an image forming apparatus including this fixing device is installed on extremely uneven ground, the bottom plate 50 (50a, 50b, Sec.

50d is a leg portion) is deformed as shown by the two-dot chain line from the solid line in Figure tJ&5. At that time, the frame, side plates, and stays of the fixing device unit supported by the bottom plate 50 are also deformed, and the distance between the roller axes and the twist angle between the rollers change. Changing the distance or the twist angle of the shaft increases the occurrence of deviation.

If the distance between the roller axes or the torsion angle of the shaft goes out of order beyond the control range of shifting that can be achieved by moving the rollers, the result will be loss of control, and the heat-resistant endless belt 23 will continue to shift in one direction. It turns out.

The above phenomenon also occurs when the misalignment detection means incorrectly detects or fails to detect due to temperature increase due to fixing heat or other reasons.

Now, for the above reason, if the heat-resistant endless belt 23 continues to lean in one direction, the end of the belt will come into contact with the abnormal deviation detection lever 1 and push the lever 1, as shown in FIG. Rotate in the direction of. At this time, since the heat-resistant endless belt 23 used here is thin and weak at the ends, the abnormal deviation detection lever 1 must be made to move smoothly with a small force. When the lever 1 rotates in the direction of the arrow as shown in the figure, the nion 2 also rotates in the same direction when it rotates coaxially and integrally with the lever 1. Then, the rack 3 that engages with the pinion 2 moves in the direction of the arrow,
The detection plate 4 is pushed, the sensor shaft 5 integrated with the detection plate 4 is rotated, and the photointerrupter 6 is turned 0N10FF.

By the way, the sensor shaft 5 has a paper ejection detection plate 7 similarly attached integrally, which normally detects the confirmation of paper ejection, and sends a signal to the microcomputer via the photo interrupter 6 to detect a certain level of paper ejection. A jam is determined based on this sequence. Therefore, the heat-resistant endless belt 2
3 is abnormally shifted, turn the abnormal shift detection lever 1.
, the pinion 2, the rack 3, etc., based on the signal from the photointerrupter 6, the microcomputer determines that there is a jam and stops the operation of the main body.

As a result, since the main body motor stops, the heat-resistant endless belt 23 stops without turning over, and is not damaged.

FIG. 6 shows a second embodiment of the invention.

In this second embodiment, when the heat-resistant endless belt 23 approaches, the belt end directly pushes the microswitch 8 to turn it on. As a result, a signal is sent from the microswitch 8 to the microcomputer to display a serviceman call.

Note that the present invention can be applied even in the case of a self-aligning method such as a crown roller as a normal deviation means, and the same effects as described above can be obtained.

[Effects of the Invention] As explained above, according to the present invention, in addition to the normal deviation detection means for detecting the normal deviation of the heat-resistant endless belt, the abnormal deviation detection means is provided, so that the deviation is further increased. Even if it is used in such a situation or environment, or if the conveyor deviation detection means does not work properly, it can detect abnormal deviation and prevent damage to the heat-resistant endless belt by stopping the operation of the main unit, etc. It is effective in preventing

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention,'! J2
The figure is a side view showing the back bearing of the driven roller in Fig. 1 being pushed down, Fig. 3 is a side view showing the bearing being pushed up, and Fig. 4 is the side view shown in Fig. 1. FIG. 5 is a perspective view of a bottom plate supporting the fixing device of FIGS. 2 and 3, and FIG. 6 is a second embodiment of the present invention. FIG. 1...Abnormality detection lever 2...Binion 3...Rack 4...Detection plate 5...Sensor glaze 6...Photo interrupter 7...Sheet discharge detection plate 8...Micro switch 23... Heat-resistant endless belt 24... Driven roller 25... Drive roller 35.
...Bearing 37...Spring 39...Cam Fig. 2 and 4 others Fig. Fig. Fig. Fig.

Claims (1)

[Scope of Claims] 1. In a fixing device that fixes a toner image on a recording material by heating it via a heat-resistant endless belt, in addition to a normal deviation detection means for detecting normal deviation of the belt, A fixing device comprising an abnormal deviation detection means for detecting an abnormal deviation. 2. The fixing device according to claim 1, wherein the abnormal deviation detection means for detecting abnormal deviation of the heat-resistant endless belt also serves as recording material discharge detection means.