JPH084582Y2 - Temperature detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a temperature detector used for temperature control of a rotating heating member such as a fixing roll of a copying machine or a laser printer.

(Prior 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 rotating heating member such as a fixing roll of a copying machine or a laser printer. Has been done.

The outline of this temperature detector is described in Japanese Utility Model Publication No. Sho 57-19612,
Disclosed by the device name "Temperature Detector",
The applicant has proposed a temperature detector with improved durability and reliability (Japanese Patent Application No. 1-116470).

FIG. 5 is a perspective view for explaining the configuration of the above proposed temperature detector.

A heat-resistant sponge 21 made of silicone rubber or the like has a recessed embedded portion 22 formed on the upper surface thereof, and a thermistor 23, which is a heat-sensitive element, is housed in the recessed portion.

The lead wire 24 of the thermistor 23 is guided by a groove 29 communicating with the recessed embedding portion 22 and led out in front of and behind the sponge 21.
On each lead wire 24 guided in the groove 29, a heat collecting plate 25 such as an aluminum foil is attached so as to collect the heat generated by the fixing roller described later and transfer it to the thermistor 23 main body. .

The sponge 21 is mounted on a printed wiring board 26 made of glass epoxy or the like, and the lead wire 24 of the thermistor 23 is
Are led to the back surface of the printed wiring board 26 through holes 30 provided in the front and rear portions of the printed wiring board 26, respectively. The ends of the lead wires 24 are soldered to the lands of the conductor pattern formed on the back surface of the printed wiring board 26.

The lead wire 27 of the temperature sensor 20 that is drawn out is
The end portion is similarly soldered to the land of the conductor pattern on the back surface of the printed wiring board 26, and the lead wire 24 of the thermistor 23 and the lead wire 27 of the temperature detector are electrically connected.

On the assembly of the printed wiring board 26 and the sponge 21 on which the thermistor 23 is mounted, a slip heat resistant insulating tape 28 of polyimide or the like is wound so as to cover the entire surface of the sponge on which the thermistor is mounted.

The temperature detector 20 configured in this way is
The mounting surface is pressed against the surface of a fixing roll, which is a rotary heating body of the copying machine, and is fixed to the base of the copying machine by projections 31 on the front and rear of the printed wiring board.

When attached to a copying machine or the like, the sponge 21 of the temperature detector 20 has a function of pressing the thermistor 23 against the rotary heating body and a heat insulating function of preventing heat from being transmitted to the rear of the thermistor 23. Further, the concave embedding portion 22 provided on the surface of the sponge 21 has a function of restricting the thermistor 23 from protruding from the surface of the sponge and preventing the polyimide tape 28 and the rotary heating body from being worn.

The printed wiring board 26 is for fixing each part such as the sponge 21, the lead wire 24 of the thermistor 23, and the like to attach the temperature detector to the device, but other than the printed wiring board can be used. .

(Problems to be solved by the invention) Compared to the temperature detector at the beginning of the disclosure, by providing the heat collecting plate and the embedded portion as described above, the thermal response time is shortened and the reliability is improved. There is.

However, in the manufacturing process, it is difficult to attach the aluminum foil to the thermistor lead wire, the attachment takes time, and there is a problem in terms of economy.

Also, in order to make good contact with the rotary heating element, the hardness of the sponge (Japan Rubber Association standard SRIS-0101 rubber hardness tester C type)
Since it has to be 15 to 20 degrees and it is quite soft, it was necessary to adjust the distance using a complicated mounting metal fitting to control the pressure applied to the rotary heating element.

If you make a mistake in the distance adjustment or if you do not adjust the distance and make contact with the rotary heating element with a strong contact pressure, the surface of the temperature detector will follow the curved surface of the rotary heating element as shown in Fig. 6. In addition, there is a drawback in that the thermistor is sunk into the sponge due to the permanent compression strain in a concave shape, and the same state is obtained when the thermistor is brought into contact with the sponge without applying pressure, and accurate temperature detection cannot be performed.

This is because one sponge is considered to have the functions of holding, pressing and insulating the thermistor.

An object of the present invention is to solve the above-mentioned drawbacks, and to provide a temperature detector capable of accurately detecting a temperature even if complicated mounting metal fittings for pressure control and complicated distance adjustment thereof are omitted.

(Means for Solving the Problems) In order to achieve the above object, a temperature detector according to the present invention has a thermistor mounted on a holding body, and the thermistor mounting surface of the holding body is provided with a heat resistant insulating film having a small friction coefficient. In the temperature detector that presses against the surface of the rotating moving body to detect the temperature of the rotating moving body, the holding body includes a sponge-like elastic body portion, and a sponge-like elastic body mounted on the upper surface of the sponge-like elastic body. It is formed from a molded part having high hardness, thermal conductivity, heat resistance, and elasticity, and the thermistor allows the element part to be accommodated in the molded part and the lead wire to contact the surface of the molded part. Mounted or embedded in the molded body, which is the surface of the thermistor holder, and is pressed against the rotary moving body through the heat-resistant insulating film to fix the lead wire. It is configured to be thermally coupled to the rotary moving body.

(Operation) According to the configuration described above, since the lead wire of the thermistor that is the heat-sensitive element is in contact with the holder having good thermal conductivity and heat resistance, it can be favorably thermally coupled to the rotary moving body.
The heat collection effect is large, and the thermal response characteristics are the same as or better than conventional ones.

In addition, since the heat-sensitive element holder with high hardness is responsible for holding the heat-sensitive element, and the sponge-like elastic body performs the function of pressing and heat insulation, the distance is not adjusted, and the rotating heat is applied with strong pressing. Even if it is brought into contact with the body, the excessive pressure is absorbed by the soft sponge-like elastic body, the surface of the thermosensitive element holding body is hardly subject to concave permanent strain, and the thermosensitive element does not dive in the sponge either. Therefore, it is possible to accurately detect the temperature in a wide pressing range without using a complicated mounting bracket and adjusting the distance. This function becomes even more remarkable when used for a long period of time under heating.

Embodiment Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 (a) is a perspective view showing an embodiment of a temperature detector according to the present invention, and FIG. 1 (b) is a front view thereof.

10m on a side of a silicone rubber sponge (sponge-like elastic body) 2 with a side length of 10mm, a thickness of 9mm and a hardness of 15 degrees.
A heat-sensitive element holding body 4 of a high thermal conductivity silicone rubber molded body having a m, a thickness of 1.2 mm and a hardness of 90 degrees is formed.

Figure 2 shows a silicone rubber sponge with a hardness of 15 degrees (vertical, horizontal and thickness 10 x 10 x 10 mm) and a silicone rubber molded product with a hardness of 80 degrees and a high thermal conductive material added (vertical, horizontal and thickness 10 x 10 x 10 mm).
And the compression length (vertical axis mm) with respect to each pressure (horizontal axis g) of 10 × 10 × 1 mm). In the figure, the solid line is Ta = 150.
The silicone rubber sponge near the operating temperature of ℃, the broken line shows the characteristics of the silicone rubber molding with a thickness of 10 mm under the same conditions, and the dashed line shows the characteristics of the silicone rubber molding with a thickness of 1 mm under the same conditions. Shows. For example, when the pressure is 500 g, the compression length of the silicone rubber sponge is 2.75 mm, but that of the high thermal conductive material-added silicone rubber molded product with a thickness of 10 mm is 0.3 mm, and the silicone rubber sponge has a compression length of nearly 10 times, When these are laminated, it is apparent that the silicone rubber sponge is dominant as the elastic body.

The element part of the thermistor having a diameter of about 1 mm is integrally molded and embedded in the central part of the molded product forming the holder 4 of the thermistor which is a heat sensitive element. The silicone rubber sponge 2 is attached to a glass epoxy printed wiring board 5 having a conductor pattern formed on its back surface.

Lead wires 6 of the thermistor protruding from both side surfaces of the thermosensitive element holder 4 are soldered to the lands of the conductor pattern on the back surface through the holes 9 provided at the front and rear portions of the printed wiring board 5, respectively. There is. Temperature sensor lead wire 7
Is similarly soldered to the land of the conductor pattern and is electrically connected to the lead wire 6 of the thermistor.

The polyimide tape 8 with a thickness of 0.05 mm is used as the thermal element holder 4
Is wound up to the back side of the printed wiring board so as to cover the entire upper surface of the printed wiring board.

High thermal conductivity silicone rubber molded thermosensitive element holder 4
Is silicone rubber, alumina, silica, zinc oxide,
High thermal conductivity characteristics are realized by mixing a small amount of boron nitride or the like, and it is integrally molded with the thermistor 3 by a mold as in normal molding.

When the response time of the temperature detector 1 according to this embodiment and the conventional temperature detector 20 shown in FIG.
The 90% response time up to 180 ° C. was 9.0 seconds in the conventional example, but was 9.2 seconds in this example, which was almost the same.

Next, the temperature change of the rotary heating body obtained by converting the resistance value of the thermistor when the above two kinds of samples were brought into contact with the rotary heating body with a diameter of 30 mm and the temperature was precisely controlled to 180 ° C. I checked. 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 a value measured 10 minutes after changing the weight.

Further, after mounting the above-mentioned two types of temperature detectors on a copying machine and bringing them into contact with each other with a pressing force of 300 g for 20,000 times of copying operation, the concave deformation distance 1 as shown in FIG. The compression strain was investigated. In the conventional example, it was 0.9 mm, but in this example, it was 0.4 mm. The detection temperature at this time was 176.0 ° C. in the conventional example and 178.8 ° C. in this example, while the temperature of the rotary heating element was 180.0 ° C.

FIG. 4 is a perspective view showing a second embodiment of the present invention.

On the silicone rubber sponge 12, the thermosensitive element holder 15 of a thermosetting silicone resin molded body having a high thermal conductivity of 10 mm on a side and a thickness of 1 mm is formed as described in the previous embodiment.

A hole 13 having a diameter of 1.5 mm is provided at the center of the heat-sensitive element holder 15, and a groove 14 having a depth and a width of 0.3 mm is formed in front of and behind the hole 13.
Are lined up.

The body of the thermistor 16 is housed in the hole 13, and the lead wire 17 is housed in the groove 14. The lead wire 17 is in a state of being in close contact with the inner wall of the groove 14, and the printed wiring board to which the silicone rubber sponge 12 is attached is similar to the previous embodiment.
It is passed through 18 holes 11 and soldered to the land of the conductor pattern on the back surface of the printed wiring board. A polyimide tape 19 having a thickness of 0.05 mm is wound around this assembly so as to cover the entire assembly. Heat sensitive element holder 15 of this embodiment
The high thermal conductivity characteristic of is realized by the same means as in the previous embodiment. The hole 13 and the groove 14 are molded by a mold. hole
In order to ensure sufficient heat conduction in the gap between 13 and groove 14,
Filled with high thermal conductivity silicone grease.

When the thermal response time by the temperature detector according to this example was measured under the same conditions as in the first example, it was 8.9 seconds, which was equivalent to the conventional example.

Next, the change in the detected temperature with respect to pressing was measured under the same conditions as in the first embodiment. As a result, the graph C shown in FIG. 3 was obtained.

Furthermore, when the permanent compression strain of the sponge was measured under the same conditions as in the first embodiment, the concave deformation distance 1 was 0.2 mm, and the detected temperature at this time was 180.0 when the temperature of the rotary heating element was 180.0.
It was 179.6 ° C with respect to ° C.

As is apparent from the above description, in the present invention, although the thermal response time is equivalent to the conventional one, the detected temperature for pressing is a value extremely close to the temperature of the rotating heating body to be measured over a wide pressing range. In addition, the concave deformation due to the permanent compression strain of the sponge was extremely small, and therefore the change in the detected temperature after long-time heating and use was also significantly small.

In the above examples, the heat-sensitive element holder was described as an example of silicone rubber or resin, but it is clear that a heat-resistant insulating molded product such as a fluororesin or a polyimide resin also exhibits the same action. Further, the same effect can be obtained by arranging the thermistor on the sponge in the direction opposite to the sponge, that is, in the form of covering the sponge with the thermistor accommodated in the heat-sensitive holder having the shape described in the second embodiment. It is what is done. The thermistor housing portion at this time may be a concave shaped portion instead of the hole.

Further, in the first embodiment etc., a silicone grease having high thermal conductivity is applied to the surface of the heat sensitive element holder, or in the second embodiment a heat collecting plate such as an aluminum foil is installed on the lead wire of the thermistor. As a result, the thermal response time can be further improved.

Furthermore, in the present embodiment, an example in which a thermistor is used as the heat sensitive element has been described, but a thermocouple or the like may be used.

(Effects of the Invention) As described above, in the temperature sensor according to the present invention, the heat collecting element and the heat sensing element holding function are shared by the heat sensitive element holder having a high hardness, and the pressing and heat insulating functions are shared by the sponge-like elastic body. Therefore, it has the following advantages.

First, the heat response time is the same as that of the conventional temperature detector in which a heat collecting plate such as an aluminum foil is attached by a complicated operation, and therefore the heat collecting plate can be omitted. Further, the detected temperature with respect to the change in the pressing force shows almost the same value as the actual temperature of the rotating heated measurement object over a wide pressing range.

This is because even if excessive pressure is applied to the temperature detector, the force is absorbed by the soft sponge-like elastic body, the heat-sensitive element is supported by the hard heat-sensitive element holder, and the sponge-like elastic body and the heat-sensitive element holder are supported. Does not undergo distortion only in a specific part, so for example, the type that is housed in the hole of the heat-sensitive element holder does not have the possibility of sneaking into the depth of the hole, and the heat-sensitive element-embedded type hardly deforms. Therefore, the magnitude of the pressing does not impair the accuracy of the detected temperature.

Therefore, the complicated mounting metal fittings for mounting the temperature detector and the complicated positioning for the pressure control which are conventionally required are unnecessary.

Furthermore, since the concave deformation of the contact surface with the rotary heating element due to the permanent strain of the sponge-like elastic body is extremely small, the change in the detected temperature after long-term heating is significantly smaller than that in the conventional example.

By obtaining the above various effects, it is possible to obtain a temperature detector having higher reliability and economy than the conventional temperature detector.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a temperature detector according to the present invention. FIG. 1 (a) is a perspective view of the temperature detector, and FIG.
Show front views respectively. Figure 2 shows a silicone rubber sponge with a hardness of 15 degrees (vertical, horizontal and thickness 10 x 10 x
10 mm) and a silicone rubber molded product with a hardness of 80 degrees and high thermal conductive material added (vertical, horizontal and thickness 10 x 10 x 10 mm and 10 x 10 x 1 mm) compression pressure (vertical axis g) (vertical axis g) Axis mm)
FIG. 3 is a graph for explaining the relationship between the detected temperature and the pressure change in the present invention and the conventional example, and FIG. 4 is a perspective view showing the second embodiment of the present invention.
FIG. 5 is a perspective view showing a conventional example of a temperature detector, and FIG. 6 is a front view for explaining defects of the conventional temperature detector. 1,10… Temperature detector 2,12… Silicone rubber sponge 3,16… Thermistor 4,15… Heat sensitive element holder 5,18… Printed wiring board 6,17… Thermistor lead wire 7… Temperature detector lead wire 8, 19… Polyimide tape 9,11,30… Hole 14… Groove

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-62-237331 (JP, A) Actual Kaihei 1-137439 (JP, U) Actual Kaihei 3-55540 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A temperature at which a thermistor is mounted on a holder, and the surface of the holder that is mounted on the thermistor is pressed against the surface of the rotary moving body through a heat-resistant insulating film having a small friction coefficient to detect the temperature of the rotary moving body. In the detector, the holding body is composed of a sponge-like elastic body portion and a molded article portion mounted on the upper surface of the sponge-like elastic body and having a higher hardness than the sponge-like elastic body and having thermal conductivity, heat resistance, and elasticity. The thermistor is mounted on the holding body in a state where the element part is housed in the molded product portion and the lead wire is in contact with or embedded in the molded product portion surface, and is the thermistor holding body surface molding A temperature detecting device characterized in that the object portion is pressed against the rotary moving body through the heat resistant insulating film to thermally bond the lead wire to the rotary moving body. .