JPH0854295A - Temperature sensor - Google Patents

Abstract

PURPOSE:To provide a temperature sensor having excellent heat response and being excellent in temperature sensing by bringing the entire surface of a thermosensitive element holder into contact with a rotary heat generator by suitable load (100-200g) of STS(soft touch sensor) even when the diameter of the heat generator is 25mm or less. CONSTITUTION:The temperature sensor 1 comprises a thermosensitive element 4, a thermosensitive element holder 3 of a molded form having an excellent thermal conductivity and heat insulation, a spongy elastic element 2 for supporting the holder 3, and a heat resistant insulating film 9 having a small frictional coefficient in smooth contact with the generator to enclose the element 4, the holder 3, wherein at least one of the holder 3 and the element 2 has a substantially equal curved surface along the shape of the generator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detector used for controlling the temperature of a rotary heating member such as a fixing roll of a copying machine or a laser printer.

[0002]

2. Description of the Related Art In recent years, a temperature detector called a so-called soft touch sensor (hereinafter abbreviated as "STS") has been put to practical use for temperature control of a rotary heating member such as a fixing roll of a copying machine or a laser printer. ing.

The outline of this temperature detector is as follows:
No. 9612, a temperature detector disclosed by the name of the device, "Temperature Detector", and the applicant later improved the thermal response, durability, etc. (Japanese Patent Application No. 2-4869).
Is proposed.

FIG. 6 (a) is a perspective view for explaining the structure of the above proposed temperature detector, and FIG. 6 (b) is a front view thereof. On the upper surface of the heat-resistant sponge 12 made of silicone rubber, a thermosensitive element holder 13 of a high thermal conductivity silicone rubber molded body is formed, and a thermistor 14 is integrally molded and embedded in the center thereof. The silicone rubber sponge 12 is attached to a printed wiring board 15 made of glass epoxy or the like having a conductor pattern formed on the back surface. Lead wires 16 of the thermistor, which are projected from both side surfaces of the thermosensitive element holder 13, are soldered to the lands of the conductor pattern on the back surface through the holes 17 provided in the front and rear portions of the printed wiring board 15, respectively. There is. Similarly, the lead wire 18 of the temperature detector is soldered to the land of the conductor pattern and is electrically connected to the lead wire 16 of the thermistor. A polyimide tape 19 covers the entire upper surface of the heat sensitive element holder 13 and is wound up to the back side of the printed wiring board 15 on the assembly of the printed wiring board 15 and the silicone rubber sponge 12 on which the heat sensitive element holder 13 is mounted. Has been.

The temperature detector 11 thus constructed is
The upper surface of the thermosensitive element holder 13 (mounting surface of the thermistor 14)
Is pressed against the surface of a fixing roll, which is a rotary heating body of a copying machine, through a polyimide tape 19, and is fixed to the base of the copying machine by front and rear projections 20 of the printed wiring board 15.

[0006]

The temperature detector 11 described above is to be solved.
In comparison with the one initially disclosed, the thermal responsiveness and durability are improved by providing the heat sensitive element holding body 13 having the function of collecting heat and holding the heat sensitive element on the upper surface of the silicone rubber sponge 12 as described above. ing. However, since the temperature detector 11 has a structure for detecting the temperature of a rotary heating body such as a heat roll on the entire surface of the thermosensitive element holder 13, the temperature of the heat roll having a diameter of 25 mm or less, which is often seen in recent years, is used. In the case of detecting, the entire surface of the heat-sensitive element holder cannot be brought into contact with the heat roll 31 with an appropriate load of STS (100 to 200 g) as shown in FIG. 5, and good temperature detection can be performed. There is a drawback that you cannot do it.

The object of the present invention is to solve the above-mentioned drawbacks and to provide the ST even if the diameter of the rotary heating element is 25 mm or less.
To provide a temperature detector which is excellent in thermal responsiveness and can perform good temperature detection by bringing the entire surface of a thermosensitive element holder into contact with a rotary heating element with an appropriate load of S (100 to 200 g). It is in.

[0008]

In order to achieve the above object, a temperature detector according to the present invention comprises a heat sensitive element, a heat sensitive element holder of a molded article having excellent thermal conductivity and heat resistance, and the heat sensitive element holder. In a temperature detector comprising a sponge-like elastic body supporting the heat-resistant insulating film having a small friction coefficient and enclosing the sponge-like elastic body and at least one of the heat-sensitive element holding body and the sponge-like elastic body. One of them has a curved surface that is substantially equal to the shape of the rotary heating body.

[0009]

According to this structure, at least one of the heat-sensitive element holding body and the sponge-like elastic body is curved along the curved surface of the rotary heating body. Therefore, with an appropriate load (100 to 200 g) of STS, When the heat-sensitive element holding body is pressed against the rotary heating body, the entire surface of the heat-sensitive element holding body makes good contact with the rotary heating body, so that accurate temperature detection can be performed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings.

FIG. 1A is a perspective view showing an embodiment of a temperature detector according to the present invention, and FIG. 1B is a front view thereof.
On a silicone rubber sponge (sponge-like elastic body) 2 having a hardness (JIS A) of 15 degrees and a side length of 10 mm, a central portion thickness of 5 mm, and a curved upper surface (R20 mm), a side length of 10 mm, A thermosensitive element holder 3 of a high thermal conductivity silicone rubber molded body having a hardness (JIS A) of 80 degrees and having a thickness of 1 mm and being curved (R20 mm) with a curvature substantially equal to that of the silicone rubber sponge 2 is formed. A thermistor 4 having a diameter of about 1 mm is integrally molded and embedded in the central portion of the thermosensitive element holder 3. The silicone rubber sponge 2 is attached to a glass epoxy printed wiring board 5 having a conductor pattern formed on its back surface.

The thermistor lead wires 6 extending from both sides of the thermosensitive element holder 3 are soldered to the lands of the conductor pattern on the rear surface through the holes 7 provided in the front and rear portions of the printed wiring board 5, respectively. It is attached. Similarly, the lead wire 8 of the temperature detector is soldered to the land of the conductor pattern and electrically connected to the lead wire 6 of the thermistor.

Polyimide tape 9 having a thickness of 0.05 mm
Is wound up to the back surface side of the printed wiring board 5 so as to cover the entire upper surface of the thermosensitive element holder 3. The heat-sensitive element holder 3 of a high thermal conductivity silicone rubber molded body achieves high thermal conductivity characteristics by blending silicone rubber with alumina, silica, zinc oxide, a small amount of boron nitride, etc. It is integrally molded with the thermistor 4 by a mold.

Here, in order to check the response time of the temperature detector, the temperature detector 1 of the present embodiment and the temperature detector 11 of the conventional example shown in FIG. 6 are shown in FIGS. As shown in (Conventional example), the heat rolls 21 and 31 with a diameter of 25 mm are precisely controlled at 25 ° C and 150 ° C.
Then, the response time between the temperatures was measured under a load of 150 g.

When the result of the measurement is expressed by the average value of the thermal time constant (time until 63.2% of 100% response), the value of the conventional example was 5.3 seconds, whereas In the example, it was 3.2 sec. As described above, since the silicone rubber sponge and the thermosensitive element holder of this example are curved as compared with those of the conventional example, the surface of the thermosensitive element holder is pressed against the heat roll with a weak pressing load. Good contact with the heat roll as a whole allows good heat collection and shortens the response time.

Next, a heat roll having a diameter of 25 mm precisely controlled at 150 ° C. was brought into contact with the above-mentioned two types of temperature detectors to convert the resistance value of the thermistor when the pressure was increased for a while to obtain the heat. I checked the temperature change of the roll. As a result, a graph as shown in FIG. 3 was obtained. Graph A is according to the present embodiment, graph B is according to the conventional example, and the measured value is 10 when the load is changed.
It is a value measured after a lapse of minutes.

As is apparent from the graph, the conventional example has an STS proper load of 100 to 200 g.
In particular, there is a temperature shift, but in the case of the present embodiment, there is almost no temperature shift with respect to the change of the pressing load, and it can be seen that accurate temperature detection is possible.

The present invention is not limited to the above embodiment. First, in the above-described embodiment, an example was described in which both the silicone rubber sponge (sponge-like elastic body) and the thermosensitive element holder were provided with curves, but for example, as shown in FIG. 2, only the thermosensitive element holder 3 is curved. May be provided, and in this case also, it is clear that the same operation as in the above-mentioned embodiment is exhibited. Although not shown, it is also possible to provide the sponge-like elastic body only with a curve. In this case, when the heat-sensitive element holder is brought into contact with the rotary heating body, the same effect as in the above-described embodiment is exhibited, but until the heat-sensitive element holder is brought into contact with the rotary heater, the heat-sensitive element holder and the sponge-like elastic body are provided. Since a slight gap is generated between and, the gap acts as a heat insulating layer and can prevent deterioration of thermal characteristics.

Further, although the thermistor is used as the thermosensitive element in the above-mentioned embodiment, a thermocouple or the like may be used, and the thermosensitive element holder may be made of fluorine resin or polyimide resin other than silicone rubber. A heat resistant insulating molded product such as the above may be used.

[0020]

As described above, according to the present invention, since at least one of the heat-sensitive element holder and the sponge-like elastic member is curved along the curved surface of the rotary heating member, the temperature detector is heated by rotation. When pressed against the body, the entire surface of the thermosensitive element holder can be brought into contact with the rotary heating element, and good heat collection can be obtained. This makes it possible to provide a highly reliable temperature detector with significantly improved response time.

[Brief description of drawings]

1A and 1B are views showing an embodiment of the present invention, in which FIG. 1A is a perspective view of a temperature detector, and FIG. 1B is a front view thereof.

2A and 2B are views showing another embodiment of the present invention, in which FIG. 2A is a perspective view of a temperature detector, and FIG. 2B is a front view thereof.

FIG. 3 is a graph for explaining the relationship between the detected temperature and the change in pressure in the temperature detectors of the present invention and the conventional example.

FIG. 4 is an explanatory view showing a state when the temperature detector according to the present invention is pressed against a heat roll with a pressing load of 150 g.

FIG. 5: Pressing load 1 from conventional temperature detector to heat roll
It is explanatory drawing which shows the state when it presses by 50 g.

6A and 6B are views showing a conventional example, in which FIG. 6A is a perspective view of a temperature detector, and FIG. 6B is a front view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Temperature detector 2 ... Silicone rubber sponge (sponge-like elastic body) 3 ... Thermosensitive element holder 4 ... Thermistor (thermosensitive element) 5 ... Printed circuit board 6 ... Thermistor lead wire 7 ... Hole 8 ... Temperature detector lead Line 9: Polyimide tape

Claims (1)

[Claims] 1. A heat-sensitive element, a heat-sensitive element holder of a molded article having excellent thermal conductivity and heat resistance, a sponge-like elastic body supporting the heat-sensitive element holder, and a rotary heating body encapsulating these. In a temperature detector consisting of a heat-resistant insulating film having a low friction coefficient that smoothly contacts, at least one of the heat-sensitive element holder and the sponge-like elastic body has a substantially equal curved surface along the shape of the rotary heating body. A temperature detector characterized in that