JPH0334572B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a temperature detection device for measuring the surface temperature of a rotating body such as a fixing roller or other stationary heating element in a fixing device such as a copying machine. Conventional temperature detection devices include first and second temperature detection devices.
There is one shown in the figure. In the figure, 1 is a heat-sensitive element such as a thermistor or thermocouple, 2 is an elastic body such as silicone rubber, 3 is a heat-resistant and abrasion-resistant insulating film such as polyimide resin or tetrafluoride resin, and 4 is a holder. The elastic body 2 is adhesively fixed to the holder 4, and the heat-sensitive element 1 is placed approximately in the center of the surface of the elastic body 2 (the depression 2a in FIG. 2), and the heat-sensitive element 1 and the elastic body 2 are It has a structure in which it is covered with a film 3. Note that the lead wire 1a of the heat-sensitive element 1 is led out to the outside via the elastic body 2 and the holder 4, and is connected to a control circuit. By the way, the temperature detecting device shown in FIG.
is embedded in the elastic body 2, and the surface in contact with the rotating body 6 is a flat surface. However, in reality, the elastic body 2
Due to the force of the film 3 to restore its original shape and the flexibility of the film 3, the surface of the film 3 corresponding to the heat-sensitive element 1 protrudes as shown in FIG. 1b. Therefore, such a temperature detection device is installed on the rotating body 6.
When the surface of the film 3 is pressed against the surface of the rotary body 6, the rotating body 6 and the surface of the film 3 slide, and the protrusion corresponding to the heat-sensitive element 1 receives strong pressure locally from the surface of the rotating body 6. Local wear occurs on the surface, the film is torn, and the heat-sensitive element 1 is destroyed.
Moreover, the surface of the rotating body 6 is damaged. Another drawback is that errors occur in the detected temperature due to localized frictional heat. Therefore, a temperature detection device shown in FIG. 2 has been proposed to improve these drawbacks. This device is different from the device shown in FIG. 1 in that the heat-sensitive element 1 is inserted into a depression 2a formed approximately at the center of the elastic body 2.
Compared to the structure shown in FIG. 1, the number of protrusions is reduced and local wear is reduced.However, there is variation in the shape of the heat-sensitive element 1, and if the shape is too small, the depression 2
If the temperature is too large, the protrusion corresponding to the heat sensitive element 1 will become large, causing local wear and damage to the heat sensitive element 1. This will lead to damage to the rotating body 6. In other words, variations in the shape of the heat-sensitive element 1 cause variations in the pressing force against the rotating body 6, resulting in a drawback that the temperature detection performance becomes unstable. The present invention seeks to correct the above-mentioned drawbacks,
The purpose is to provide a temperature detection device that does not cause variation in the pressing force against a temperature-measuring object even if there is variation in the shape of the heat-sensitive element, and has stable temperature detection performance. Embodiments of the present invention will be described below with reference to FIG. 3 and subsequent figures. Incidentally, the same members as in FIGS. 1 and 2 are indicated by the same reference numerals, and explanations thereof will be omitted. 3 and 4 show the first embodiment. In this embodiment, the difference from FIGS. 1 and 2 is that two parallel cuts 2b and 2b are provided on one side of the elastic body 2. . The material of the elastic body 2 is a synthetic rubber such as silicone rubber or fluorine rubber, or a glass fiber aggregate, polyurethane, polyethylene, or a combination thereof, which has heat resistance and elasticity. It's good to have. Then, the heat-sensitive element 1 is placed at the center of the independent center part 2c formed by the notches 2b, 2b, and the elastic body 2 is adhesively fixed to the holder 4 as shown in FIG. Cover with insulating film 3.
By adopting such a structure, the heat-sensitive element 1 can be buried with a small force, so that a more reliable temperature detection device can be manufactured. FIG. 5 shows still another embodiment of the elastic body 2,
Notches 2b, 2b are provided in the same manner as the notches 2b, 2b of the first embodiment shown in FIG. 3, and two notches 2d, 2d perpendicular to these are provided. Then, four cuts 2b, 2b, 2d, 2
The heat-sensitive element 1 is arranged in the central part 2e, which is independent by the distance d. In this embodiment as well, by adopting a structure similar to that shown in FIG. 4, it is possible to obtain a temperature detection device that is more reliable than the first embodiment. Here, in the conventional example shown in FIGS. 1 and 2 and the present example shown in FIGS. The table below shows the pressing force required to press the elastic body 1 and embed it in the elastic body 2 until it is at the same position.

[Table] Here, the values measured by the method shown in FIG. 2 are obtained when the depth of the recess 2a was formed to be slightly shallower than the size of the heat-sensitive element 1. In this manner, the insulating film 3 of the present invention makes contact with the rotating body 6 with a weaker force than the conventional one, so that the pressing force against the object to be measured is averaged, and the wear of the insulating film 3 is reduced. In addition, in the above embodiment, the elastic body 2 has cuts 2b,
2b, 2d, and 2d are shown, but these may be grooves, and moreover, portions corresponding to the grooves may be formed in advance in the mold at the stage of molding. Furthermore, in the first embodiment, the notches 2b, 2b were formed from one surface of the elastic body to the corresponding opposite side surface, but in the case of FIG. There is no need to form a notch. It goes without saying that the notch portion may be provided in a recessed portion as shown in FIG. That is, when mounting the heat-sensitive element 1, the shape is not limited to the shape of the present invention as long as it works independently of the surroundings. Furthermore, it is possible to adjust the pressing force to some extent by adjusting the depth of the cut portion. Further, in this embodiment, as shown in FIG. 4, the lead wire 1a of the heat-sensitive element 1 is configured to be pushed through the inside of the elastic body 2, but as shown in FIGS.
When the lead wires 2b, 2b, 2d, and 2d are provided, it may be preferable to embed the lead wire 1a in the notch 2b or 2d and take it out from the side surface of the support 4. As described above, the present invention forms at least two cuts in the elastic body and arranges the infectious element in the independent central part, so that when pressed against a body to be measured such as a rotating body, the heat-sensitive element part Because the surrounding elastic bodies work independently and the pressure applied to the heat-sensitive element is small, the flexible insulating film has no protrusions on its surface, prevents local wear, and extends the life of the product. Accurate temperature detection is possible, and it is possible to prevent damage or scratches to the heat-sensitive element or the object to be measured.Furthermore, even if the shape of the heat-sensitive element varies, the heat-sensitive element is always independent of the insulating film and the elastic body. Since it is uniformly pressed and fixed by the central portion, it has the effect that temperature detection failure does not occur.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing examples of conventional temperature detection devices, FIGS. 3 to 5 show embodiments of the temperature detection device of the present invention, FIGS. 3 and 5 are perspective views of elastic bodies, and FIGS. The figure is a sectional view of the assembled state. 1... Heat sensitive element, 2... Elastic body, 2b, 2b,
2d, 2d...notch, 2c, 2e...independent central portion, 3...insulating film, 4...holding body.

Claims (1)

[Claims] 1. A holder, an elastic body fixed to the holder and having at least two cuts formed on its surface, and a heat-sensitive element placed on an independent central portion formed by the cuts of the elastic body. 1. A temperature detection device comprising an insulating film covering the surface of an elastic body including a heat-sensitive element.