JPH04115283A - Fixing device - Google Patents

Abstract

PURPOSE:To clean the detecting part of a thermister by sequentially moving the contact positions of three temp. detecting members to three positions where the temp. detecting member is not in contact with a heating roller and a cleaning member, and not in contact with neither of them, and simultaneously, carrying out switching so as to locate, at least, one of the temp. detecting members at any of three positions. CONSTITUTION:Toner which can not be removed by a cleaning roller 9 is stuck and heaped on a thermister 13 (P1) located at the contact position P1 of the heating roller 2. A thermister 13 (P2) located at the contact position P2 with respect to the cleaning member comes into contact with the outer periphery of the cleaning roller 9, and the toner stuck at the P1 is removed. A thermister 13 (P3) located at a noncontact position P3 with respect to neither of the heating roller and the cleaning member measures the atmosphere temp. T2 of a circumference, and outputs a corresponding signal to a controller 17. When a motor 12 is driven and a disc 11 is rotated by 120 deg., the thermisters 13 located at respective positions P1, P2, and P3 are moved to respective positions P2, P3, and P1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fixing device that heats and melts unfixed toner attached to a transfer material in an image display device such as a copying machine or a printer. It is related to.

[Conventional technology]

Conventionally, it is known that the fixing device includes a heating roller having a heat source, a pressure roller in pressure contact with the heating roller, a cleaning member in contact with the heating roller, and a thermistor in contact with the heating roller.

In this fixing device, a transfer material having unfixed toner is introduced into a nip portion between a heating roller and a pressure roller, and the unfixed toner is heated and melted and fixed to the transfer material. On the other hand, toner that has adhered to the heating roller without being fixed to the transfer material is removed by a cleaning member. Also, thermistor beam? The surface temperature of the heated roller is measured, and the heat source is controlled based on the measurement result.

[Problem to be solved by the invention]

However, in the fixing device, the toner on the surface of the heating roller is not removed by the cleaning device, and some of the toner that has passed through the contact portion of the cleaning member without being removed is detected by the thermistor. The problem has been that the sensitivity of the square mister decreases due to the adhesion and accumulation of the particles.

Another problem is that conventionally, the detection part of the thermistor was cleaned during periodic inspections of image forming apparatuses, and cleaning the thermistor that is in contact with the heating roller is not easy and the work is extremely inefficient. It had

[Means to solve the problem]

The present invention has been made to solve the above problems,
In the fixing device, at least three temperature detecting members are provided, and these temperature detecting members are arranged at a first position in contact with the heating roller, a second position in contact with the cleaning member, and at any of the heating roller and the cleaning member. A switching device is provided that sequentially moves to a non-contact third position and positions at least one temperature detection member in the three positions.

Second Embodiment A practical example of the present invention will be described below with reference to the accompanying drawings.

In the fixing device 1 shown in FIG. 1, the upper fixing roller 2 has a heater lamp 3 built therein. The lower fixing roller 5 is disposed parallel to the upper fixing roller 2, and is in pressure contact with the upper fixing roller 2 at a nip portion 6.

The upper fixing roller 2 is heated by lighting the heater lamp 3, and rotates in the direction of arrow a based on the drive of the motor 4. The lower fixing roller 5 is driven by the upper fixing roller 2 and rotates in the direction indicated by the arrow. These rollers 2 and 5 sandwich the transfer material 20 having the toner image 21 conveyed from the direction of the arrow at the nip portion 6, and the heated upper fixing roller 2
The toner image 21 is melted and fixed. Also, toner image 2
The transfer material 20 with the image 1 fixed thereon is separated from the rollers by separation claws 7 and 8 that are in contact with the rollers 2 and 5, respectively, and is discharged to a discharge section (not shown).

The cleaning roller 9 has oil on its outer periphery.
It contacts the upper fixing roller 2 and is driven and connected to the motor 4 via a drive transmission mechanism (not shown), so that it rotates in the direction of arrow C in synchronization with the upper fixing roller 2. I wanted to,
The cleaning roller 9 rotates together with the rotation of the upper fixing roller 2, and the toner adhering to the upper fixing roller 2 is removed by the cleaning roller 9 at the contact portion between the two.

As shown in FIG. 2, the switching device 10 consists of a disc 11 and a motor 12 that rotationally drives the date board 11, and three thermistors 13 are provided at equal intervals on the outer periphery of the disc 11. .

As the motor 12 rotates, the disc 11 rotates in the direction of the arrow e, and the thermistor 13 moves to a first position P1 where it contacts the upper fixing roller 2, a second position P2 where it contacts the cleaning roller 9, a second position P2 where it contacts the upper fixing roller 2, and a second position P2 where it contacts the upper fixing roller 2. cleaning roller 9
They each switch to the third position P3 in which there is no contact with any of them, so that one thermistor is always in each position.

The thermistors 13 are each connected to contacts 14 provided on the side surface of the disc 11, and are connected to the thermistor contacts 14 at the first position P1 and the third position P3 or to the control device 1.7. It is in contact with Plano 1516.

Therefore, the thermistor 13 (P
I) measures the surface temperature T1 of the upper fixing roller 2 and outputs the result to the control device 17. The control device 17 determines whether the surface temperature Tl of the upper fixing roller 2 is appropriate based on the signal from the thermistor 13 (PI), and if it is high, turns off the heater lamp 3 to lower the temperature; Turn on the heater lamp 3 to raise the temperature. Further, toner that could not be removed by the cleaning roller 9 adheres and accumulates on the thermistor 13 (Pl,) located at the first position P1.

The thermistor 13 (P2) located at the second position P2 contacts the outer peripheral surface of the cleaning roller 9, and as described above, the thermistor 13 (P2) is located at the first position P2.
The attached toner is removed at position Pl.

However, this thermistor 13 (P2) is not connected to the control device 17 and does not output a signal to the control device 17 (the thermistor 13 (P3) located at the third position P3 is not connected to the surrounding atmospheric temperature. T2 is measured and a corresponding signal is output to the control device 17.

Drive the motor 12 to rotate the disc 11 by 120° in the direction of arrow e.
When rotated, they are at positions pl and p2p3, respectively.)
Thermistors I3(P1), I3(P2)i3(
P3) are at positions P2, P3. Move to Pi.

The timing of rotating the disc 11 and switching the thermistor 13 may be done automatically when a predetermined number of foils have been produced, or it may be done by operating a changeover switch (not shown). Alternatively, as will be described later, contamination of the thermistor may be detected and the determination may be made based on the result.

Next, the degree of contamination and abnormality of the thermistor is detected based on the signals input to the control device 17 from the thermistor 13 (Pl) located at the first position P1 and thermistor +3 (P3) located at the third position P3. The process will be explained.

When the doo-mister 13 is clean, the surface temperature of the upper fixing roller 2 (T) and the quality of the atmosphere at the third position are T.
2 satisfies the relationship of straight line A shown in FIG.

If the thermistor 13cPI at the first position P1) is dirty, the surface temperature T1 will be affected by the amount of toner that has accumulated.
On the other hand, the ambient temperature T2 is detected to be lower, resulting in the relationship shown by the dashed line in FIG.

So, is it the relationship between the surface temperature T1 and the ambient temperature T2?
If it is in the area surrounded by the straight line B, which is shifted by tl (for example, t+"1°C), it is within the allowable range, and the position of No.-Mister 13 is left as it is without changing the position. Temperature detection continues in this state.

Also, the relationship between the surface temperature T1 and the ambient temperature T2, or the straight line B
, B', if it is in the area surrounded by straight lines c and c' which are shifted by tl (for example, 20'C) from straight line A, then the thermistor 13 (Pl) is dirty and the disk 11 , move the thermistor 13 (PL) from the first position P1 to the second position P2 and clean it using the cleaning roller 9, and move the cleaned thermistor 13 (P3) from the third position P3 to the second position P2. 1 to the position P1 and brought into contact with the upper fixing roller 2.

Furthermore, the relationship between the surface temperature TI and the ambient temperature T2 is the straight line c.
, c', for example, if there is a curved relationship, it is determined that the thermistor P1 in contact with the upper fixing roller 2 is abnormal,
A warning is issued by a thermistor failure indicator lamp, etc. On the other hand, if the relationship is as shown by curve E, it is determined that the thermistor 13 (P3) located at the third position P3 is abnormal, and a warning is issued in the same manner. However, if the thermistor is dirty, B', C
(Due to dirt on the thermistor, the surface temperature is detected to be lower than the ambient temperature.) Therefore, it can be considered that fluctuations to the B and C sides are almost impossible except for failures. Therefore, by making the allowable ranges on the B and C sides narrower than on the BC' side, it is also possible to detect abnormalities more quickly.

In the above explanation, the thermistor 13 is provided on the outer periphery of the disk 11, and by rotating this disk: the two thermistors 13 are moved to the first (Pi), second (P2), and third (P3) positions. As shown in FIG. the first position P
l second position p2. It may be moved to the third position P3.

Further, three thermistors are provided, or at least three are sufficient.

Furthermore, although the case where a cleaning roller is used as the cleaning member is shown, a wafer type cleaning member may also be used.

〔Effect of the invention〕

As is clear from the above description, in the fixing device according to the present invention, at least three temperature detecting members are arranged at a first position where the temperature detecting member contacts the heating roller, a second position where the cleaning member contacts the heating port, and a second position where the temperature detecting member contacts the heating roller. La and cleaning section +4
In each case, the temperature detection member is moved to the third position in order, and at least one temperature detection member is located in the three positions marked in (a). Dirty detector parts are cleaned by a cleaning member. Therefore, there is no need to clean the temperature detection member during periodic inspection, making inspection work easier.

Furthermore, dirt on the thermistor can be detected based on the measurement results of the temperature detection member in the third position and the temperature detection member in the first position, and the temperature detection member can be switched based on that. Constantly stable temperature detection is possible.

Furthermore, since the sensitivity of the temperature detecting member can be maintained in a good condition as described above, the temperature of the heating roller can be controlled at an appropriate temperature. Therefore, it is possible to improve the safety of the image forming device without burning paper jammed in the fixing device, and it is possible to always maintain the ideal fixing state and obtain good printed images. be.

[Brief explanation of drawings]

FIG. 1 is a side view of the fixing device, FIG. 2 is a diagram showing the configuration and circuit configuration of the switching device, and FIG. 3 is a diagram showing the relationship between the surface of the constant blue upper roller (9) and the ambient temperature. FIG. 4 is a side view showing another embodiment. 1. Fixing device, 2. Upper fixing roller, 3. Heater lamp, 5. Lower fixing roller, 6. 2. Section, lO/switching device,
11 Disc, 13 Thermistor, Pl--first position, P2 second position, P3 third position. Patent applicant: Minolta Camera Co., Ltd. Agent Patent attorney: Haka 1 (1 person) Figure 1 Figure 4 Figure 9: Cleaning roller\/'''5: Lower fixing roller

Claims (1)

[Claims] (1) A transfer material having unfixed toner is sandwiched and conveyed between a heating roller and a pressure roller that is in pressure contact with the heating roller, and the unfixed toner is melted and fixed on the transfer material, and the heating roller that is in contact with the unfixed toner is In the fixing device, the fixing device is configured to be cleaned with a cleaning member, and the temperature detecting members are arranged at a first position in contact with the heating roller, a second position in contact with the cleaning member, and a second position in contact with the heating roller. A fixing device comprising: a switching device that sequentially moves to a third position not in contact with either the roller or the cleaning member, and positions at least one temperature detection member in the three positions.