JPS6124903Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature sensor that detects the temperature of a rotating body that rotates at a relatively low speed, such as a fixing heat roller, or a stationary body inside a copying machine.

A conventional temperature sensor of this type had a configuration as shown in FIGS. 1 and 2. That is, a temperature-sensitive element 2 such as a thermistor is placed on a heat-sensitive plate 1 made of metal, and a protector 3 made of silicone rubber or the like is formed thereon. The conductive wire 2a of the temperature sensing element 2 is covered with an insulating tube 2b and led out to the outside. The heat-sensitive plate 1 of such a temperature sensor is pressed onto a rotating body (not shown) by utilizing its elasticity to detect the temperature on the surface of the rotating body.

However, since the heat-sensitive plate 1 is metal, the conduction of heat is inaccurate and there is a temperature difference with the rotating body, making it impossible to accurately detect the temperature. Could not detect temperature. In addition, since the conducting wire 2a from the temperature-sensitive element 2 adhesively fixed to the heat-sensitive plate 1 is relatively thick like a composite wire, the elastic force of both the heat-sensitive plate 1 and the conducting wire 2a acts, and the elastic force may be affected depending on the method of fixing the conducting wire. There were variations in elastic force. As a result, errors may occur in the detected temperature depending on the method of fixing the conducting wire. Furthermore, if the elastic force is made too strong, the rotating body may be scratched because the heat-sensitive plate 1 is made of metal.

For this reason, a temperature sensor as shown in FIG. 3 was devised. That is, the temperature sensing element 2 is placed on one surface of an elastic body 4 such as silicone rubber, and a thin film tape 5 is adhered and fixed. This is a temperature sensor with a sensing surface that fits well to the shape of the object to be detected, so there is little heat radiation from the surroundings, and therefore a relatively small thermal time constant. However, since the conducting wire 2a passes through the inside of the elastic body 4 and the elastic body 4 expands and contracts, the conducting wire 2a must be flexible and must also be a thin wire from the viewpoint of reducing heat radiation. For this reason, platinum wire has usually been used as the conducting wire 2a. Therefore, assembly of this temperature sensor is complicated and difficult, and it is expensive and not suitable for mass production. Furthermore, there is a risk that wire breakage may occur during use, making temperature control impossible.

Therefore, the present applicant has applied for a temperature sensor shown in FIGS. 4 to 6. This will be explained below based on the figures.

In Figures 4 and 5, vinyl chloride,
A conductor foil 9 (about 35 μm thick) is formed by etching, adhesion, etc. on an insulating thin film sheet 8 (about 25 μm to 200 μm thick) made of resin such as polyester, polyethylene, polyimide, or fluorocarbon resin. Furthermore, an insulating thin film sheet 7 (about 25 μm to 200 μm thick) made of the same material as the insulating thin film sheet 8 is formed thereon by adhesion, heat fusion, or the like. This state is similar to that of a so-called flexible printed circuit board. A hole is formed at a predetermined location on this sheet 7 using a mechanical or chemical method to expose a portion of the conductive foil 9. A temperature sensing element 6 such as a bead-shaped thermistor is inserted through this opening and placed on the sheet 8. And the conductor 6 of the temperature sensing element 6
A is connected to the connecting portion 9a of the conductive foil 9 by soldering, welding, or the like. Further, the end portion of the conductor foil 9 is exposed as an output conductor lead-out portion 9b. The temperature sensor 10 is formed by the above steps.

Figure 6 shows the usage status of the temperature sensor 1.
0 into a U-shape, and insert both ends into the insertion hole 11a of the U-shaped holder 11, and insert an elastic body 12 such as silicone rubber into the gap between the holder 11 and the temperature sensor 10. intervene. Note that the sheet 8 of the temperature sensor 10 and the holder 11 are bonded together with an adhesive or the like. Further, an output conductor 13 is connected to the output conductor lead-out portion 9b of the temperature sensor 10. Further, it is preferable that the temperature sensing element 6 is fixed in contact with the sheet 8 using an adhesive such as silicone rubber.

When the surface of the sheet 8 is brought into contact with an object to be detected, such as a rotating body or a fixed body, the temperature of the object to be detected is transmitted to the temperature sensing element 6 via the sheet 8. Here, since the temperature sensor 10 is pressed against the object to be detected by the elastic body 12, the sensing surface fits well to the shape of the object to be detected, so that the heat radiation from the surroundings is small, and the thermal time constant is therefore reduced. can do. Furthermore, by having the conductor foil 9 within the sheets 7 and 8, the conductor foil 9 moves in the same manner as the sheets 7 and 8, resulting in a uniform force action, improving adhesion and reducing the risk of oxidation and disconnection. has.

By the way, the temperature sensor 10 described above is operated in a direction perpendicular to the rotating roller 14, that is, as shown in FIG.
The roller 14 is mounted so that the point a is perpendicular to the axial direction of the roller 14. However, with this method, the fixing roller 14 used in the copying machine has a fluororesin coating on its surface.
The coating surface of the rotating roller 14 is scratched by the edge 8a of the sheet 8, which is pressed under a load of nearly 200g, which makes it impossible to accurately detect the surface temperature and shortens the life of the roller 14. The disadvantage was that it was shortened.

The present invention was developed in view of the above points, and its purpose is to extend at least a portion of the lower sheet to form a cross shape, so that the edge of the sheet lightly contacts the roller. The purpose of this is to provide a temperature sensor that is protected from scratches.

Next, an embodiment of the present invention will be described with reference to FIGS. 8 to 10.

In addition, in the drawings, the same reference numerals as those in FIGS. 4 to 7 indicate the same members, and explanations thereof will be omitted.

In this embodiment, a projecting piece 8b is formed by extending the lower sheet 8 from the portion where the temperature sensing element 6 is provided in a direction perpendicular to the longitudinal direction.

The temperature sensor 10 is then attached to the holder 11 in the same manner as in the conventional case, and a load of about 200 g is applied to the roller 14 as shown in FIGS. 9 and 10.

That is, in FIG. 9, the longitudinal direction of the temperature sensor 10 is arranged perpendicular to the axial direction of the roller 14, and in FIG. 10, it is arranged parallel to it.

In the case of FIG. 9, the edge portion of the temperature sensor 10 that comes into sliding contact with the roller 14 is formed by the protrusion 8b.
However, almost no load is applied to this protruding piece 8b, and since the protruding piece 8b is an extension of only the lower sheet 8 and is extremely thin, it is extremely thin. It has great flexibility and therefore does not damage the roller 14.

Also, in the case of FIG. 10, the edge portion of the temperature sensor 10 does not come into direct sliding contact with the roller 14, but the protrusion 8b does.
By the same action as in the embodiment of FIG. 9, the roller 14
It will not cause any damage.

As described above, the present invention extends the protrusion from at least the portion of the lower sheet that makes sliding contact with the roller in a direction perpendicular to the longitudinal direction of the sheet, thereby providing a highly flexible protrusion to the roller. Only the edge portions are in sliding contact, so that damage to the roller can be effectively prevented, the life of the roller can be extended, and temperature can be accurately detected.

[Brief explanation of the drawing]

Figures 1 to 7 show conventional temperature sensors;
The figure is a plan view, FIG. 2 is a cross-sectional view taken along the line shown above, FIG. 3 is a cross-sectional view of another example, FIG. 4 is a plan view of still another example, and FIG. Fig. 6 is a cross-sectional view of the above temperature sensor attached to the holder, Fig. 7 is a perspective view of the state in use, and Fig. 8 to 10
The figure shows an embodiment of the temperature sensor of the present invention.
The figure is a plan view, and Figures 9 and 10 are perspective views of the device in use. 6... Temperature sensing element, 7, 8... Insulating thin film sheet,
8b... Projection piece, 9... Conductor foil.

Claims (1)

[Scope of utility model registration request] Forming a conductor foil in a predetermined pattern between two upper and lower insulating thin film sheets, cutting out a part of the upper sheet and inserting a temperature sensing element, and connecting the conductor of the temperature sensing element to the conductor foil, In addition, a protrusion is formed extending in a direction perpendicular to the lower sheet at the portion of the lower sheet that comes into contact with the detected object, which is a rotating roller, and the two sheets are further interposed between the two sheets through an elastic body such as a sponge. A temperature sensor, characterized in that the elastic body is attached to a holding body and does not protrude to the protruding piece of the lower sheet.