JPS6285831A - Temperature detector - Google Patents

Abstract

PURPOSE:To detect an accurate temperature by improving thermal conduction of a fixed roller and a thermosensitive element. CONSTITUTION:The temperature of an object to be measured can be detected accurately and rapidly by collecting heat from the object to be measured via a heatproof tape 5 by aluminum foil 4 as a good thermal conduction plate provided in opposition to the object to be measured and detecting the heat with a thermistor 3 as the thermosensitive element 9. Further, since the aluminum foil 4 is buried in the recessed surface 2 of elastic material 8 (sponge 1) and can also collect the heat transmitted to the elastic material 8 via a heatproof tape 11 (5), the temperature can be detected accurately and rapidly. Then, the temperature of the object to be measured can be kept constant by controlling the temperature of the object to be measured according to the detected temperature by a control circuit. In this way, the good thermal conduction plate can collect the heat from the object to be measured and transmit it to the thermosensitive element 9 efficiently and accordingly, the thermosensitive element 9 can detect the temperature rapidly and accurately.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a temperature detection device for detecting the surface temperature of a fixing roller in a roller-type heat fixing device of an electrophotographic copying machine, and more specifically, the present invention relates to a temperature detection device that detects the surface temperature of a fixing roller in a roller type heat fixing device of an electrophotographic copying machine. The present invention relates to a soft touch sensor (STS) having an embedded element.

(Prior Art) In a copying machine, a fixing roller equipped with an internal heater, for example, is used to fix a toner image transferred onto copy paper. Then, the copy paper comes into pressure contact with the fixing roller and is further heated, so that the toner is fused to the copy paper and the toner image is fixed.

The surface temperature of the fusing roller must be maintained at a constant high temperature, so the surface temperature is constantly detected by a temperature detection device, and the operation of the heater inside the fusing roller is controlled according to the detected temperature. There is.

As shown in FIG. 4, an example of a conventional detection device, the detection device has a recess 10 in an elastic material 8 such as a sponge, and holds a heat-sensitive element 9 such as a thermistor in the recess while the elastic material 8 is heat-resistant. It is covered with tape (polyimide resin) 11. As shown in FIG. 5, the detection device detects the surface temperature of the fixing roller 6 with the heat-sensitive element 9 in contact with the fixing roller 6 via the heat-resistant tape 11 while receiving the pressing force from the slope spring 12.

However, in this device, the heat-sensitive element detects the temperature of the fixing roller via the heat-resistant tape, so the heat conducted to the heat-resistant tape is transferred to the elastic material, and the heat is absorbed by the elastic material before the temperature of the heat-sensitive element rises. However, there is a problem in that the thermal response of the detection device is poor and accurate temperature detection cannot be performed. Furthermore, overshoot occurs in the fixing roller, toner is fused to the surface of the fixing roller, and the surface becomes dirty.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide an STS type temperature detection device that is capable of accurately detecting temperature by improving heat conduction between a fixing roller and a heat-sensitive element. It's about doing.

(Means and effects for solving the problems) The present invention has the following features:
In a temperature sensing device that detects the surface temperature of an object to be measured by contacting it, a heat-sensitive element is integrated by being sandwiched between thin heat-conducting plates, and this is mounted on an elastic material facing the object to be measured. A temperature sensing device for a copying machine, etc., which is flattened and buried in a recess, and the elastic material is covered with a heat-resistant tape!
be.

In other words, a heat-conducting plate placed opposite the object to be measured collects heat from the object through the heat-resistant tape, and a heat-sensitive element detects the heat.1.The temperature of the object to be measured can be determined accurately and quickly. Can be detected. In addition, since the thermally conductive plate is embedded in the recess of the elastic material, it can also collect the heat transmitted to the elastic material via the heat-resistant tape, making it possible to accurately and quickly detect temperature. By controlling the temperature of the object to be measured according to the detected temperature, the temperature of the object to be measured can be kept constant.

(Example) An example of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a sectional view of a temperature detection device for detecting the temperature of a fixing roller of a copying machine, for example. The elastic material is a sponge 1 formed into a substantially trigonal shape, and has a shallow rectangular recess 2 on its surface facing the fixing roller 6 .

On the other hand, a thermistor 6 is used as a heat-sensitive element, and an aluminum foil 4 is used as a thermally conductive plate.As shown in FIG. 0 The thermistor 6 in the recess 2 is located on the same plane as the plane around the recess so as not to protrude outside the recess 2. Furthermore, the thermistor 6 inside the recess 2 is located on the same plane as the plane around the recess 2, and also closes the recess 2 and the sponge 1.
The entire surface of the sponge 1 is covered with a heat-resistant tape (polyimide resin) 5 in order to protect the sponge 1 from heat and improve sliding properties with the fixing roller 6. And thermistor 3 is the fifth
Like the conventional detection device shown in the figure, it is connected to a temperature detection circuit and a control circuit that controls the operation of the heater 7 in the fixing roller 6.

The detection device is in contact with the fixing roller 6 such that the thermistor 3 faces the fixing roller 6, and the thermistor 3 detects the heat of the fixing roller 6 via the heat-resistant tape.

The thermistor 6 is held between aluminum foils 4, and the aluminum foil 4 has a planar spread facing the fixing roller 6, so that heat can be efficiently collected from the fixing roller 6 via the heat-resistant tape 5. .

Therefore, the thermistor 6 that is in contact with the aluminum foil 4 sensitively responds to the temperature of the aluminum foil 4, and its resistance value changes depending on the change in detected temperature, so that the heater control of the fixing roller 6 can be performed accurately.

FIG. 6 is a graph comparing the characteristics of the detection device of the present invention and the conventional detection device, showing the characteristics of the present detection device and the characteristics of the conventional detection device. show.

When the detection temperature of the fixing roller surface is set to 180°C,
The conventional device took 40 seconds to detect 180° C., and when the operation of the heater 7 was stopped, the surface temperature of the fixing roller 6 was much higher than the detected temperature, causing an overshoot. However, according to the detection device according to the present invention, it takes 35 seconds to detect 180° C., which is shorter than the conventional method. In other words, it is possible to quickly detect a rise in the surface temperature of the fixing roller 26.1, the temperature is detected immediately after the fixing roller 26 reaches the set temperature, and at that time the heater 7
Overshoot can be prevented by controlling the operation to stop.

Nao: In this embodiment, as shown in Figure 2, a thermistor 6 is sandwiched between flat aluminum foils 4 and integrated! Yes, but
As shown in FIG. 3, the thermistor 6 may be inserted into a hollow cylindrical body formed by aluminum foil 4, and the cylindrical body may be crushed and clamped. Mono f is also good. Furthermore, it is also possible to use other metals with good thermal conductivity in place of the aluminum foil 40.

(Effects of the Invention) According to the temperature detection device of the present invention, the heat sensitive element and the thermally conductive plate are integrated to improve thermal conductivity, so that the thermally conductive plate absorbs heat from the object to be measured. Heat is collected and efficiently transmitted to the heat-sensitive element, so that the heat-sensitive element can quickly and accurately detect temperature. Furthermore, since it has good thermal responsiveness, it is possible to perform effective control according to the detection results, and there is no problem even when, for example, a copying machine is operated intermittently.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an embodiment of the present invention, Figs. 2 and 6 are perspective views of an example of the configuration of a thermistor and aluminum foil, Fig. 4 is a sectional view of a conventional detection device, and Fig. 5 is a sectional view of a fixing roll. FIG. 6, which is a sectional view of the provided detection device, is a graph showing the characteristics of the detection device. Symbols in the figure: 1... Sponge, 2... Concavity, 3... Thermistor, 4... Aluminum foil, 5... Heat resistant tape, 6... Fixing roller, 7... Heater, 8 ...
Elastic material, 9... Heat sensitive element, 10... Recessed portion, 1
1... Heat-resistant tape, 12... Leaf spring @ 1 Figure 2 Figure j13 Nationally owned 4
Figure 5 Figure 6 Time M (seconds)

Claims (1)

[Claims] In a temperature sensing device that detects the surface temperature of an object to be measured by contacting it, a heat-sensitive element is integrated by being sandwiched between thin heat-conducting plates, and this is mounted on an elastic material facing the object to be measured. A temperature sensing device for a copying machine, etc., which is flattened and buried in a recessed portion, and the elastic material is covered with a heat-resistant tape.