JPH09213183A - Small-size thermostat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform, small-sized thermostat by providing a thin film integrated part having a micro shape and bimetal function in a part of a movable conductor. SOLUTION: A thin film integrated part 3 having a micro shape and bimetal function is provided in a part of a movable conductor 1, which has flexibility and is treated by micro working, by a thin film integration means such as vacuum evaporation, sputtering, etc. A part of the thin film integrated part 3 integrated with the movable conductor 1 is formed into a bent state. This constitution permits the movable conductor 1 to be bently deformed by difference in thermal expansion in heating so as to open a contact part 2 and therefore can cut off the current. A small and light-weight thermostat used for the secondary side of a power supply for an electronic device under comparatively low voltage and low current can be thus provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermostat, which is a kind of temperature sensitive switch that operates by sensing temperature.

[0002]

2. Description of the Related Art A conventional thermostat is a so-called bimetal, which is formed by rolling a raw material obtained by joining two kinds of alloys, which are called bimetals and having different thermal expansion coefficients, directly or through an intermediate layer by a method such as hot rolling. Utilizing thermal deformation, the contact of the switch is turned on or off directly or indirectly depending on the ambient temperature. 5 to 7 show sectional structures in the vicinity of contact opening / closing portions of a general thermostat. FIG. 5 shows an example in which the bimetal (3) is directly used for the movable conductor 1. In FIG. 6, a bimetal 3 is arranged near the independent movable conductor 1 to indirectly open and close the contact 2. In FIG. 5, the bimetal 3 is curved in advance so that thermal deformation appears as a snap action, and the movable conductor 1 receives the snap action to open and close the contact 2.

[0003]

Conventionally, a thermostat is built in the primary side of a power source of an electric heater, a motor, a transformer, etc., and when the ambient temperature or its temperature exceeds a predetermined value, the power source of an electronic device incorporating them. It was generally used for the purpose of temporarily opening the contact directly connected to the primary side. Therefore, the conductive part of the thermostat has 10
A power supply voltage of about 0 V or 200 V is directly applied, and the load current of the entire electronic equipment flows through the contacts and conductive parts. Therefore, the volume capacity equivalent to that and various safety regulations represented by UL and UL A similar creepage and space insulation distance was required, and it was impossible to reduce the size below the size regulated by it. However, in recent years, it has been built into small rechargeable battery packs, etc., whose production volume has increased rapidly with the expansion of demand for portable electronic devices, and is used in the thermostat itself, such as when it is used as an extremely small safety device. There is an increasing tendency to require smaller size and lighter weight.
In these cases, the thermostat is used for the secondary side of the power source of electronic devices under low DC voltage and low current conditions, so despite the fact that it is not subject to regulations such as the insulation distance according to the previous safety rules, However, there is still little technical innovation to meet the demands of the above, and there is no choice but to use a relatively large thermostat manufactured by the conventional concept of direct connection to the primary side of the power source.This is due to expanding demand for thermostats and thermostats such as small secondary battery pack It was also a cause of hindering the miniaturization of small electronic devices and parts that have built-in components.

Another factor that prevents the thermostat from becoming smaller and lighter is that the bimetal, which is the main component of the thermostat, normally presses two kinds of alloy materials together.
It is made by rolling. The bimetal incorporated in the thermostat is formed by pressing the rolled and rolled material into a desired shape and dimension by a normal press working, but the width and thickness of the bimetal formed through the steps of joining and rolling may be different depending on the manufacturing method of the material. Cannot be made so small from the viewpoint of forming the material, and the thickness is limited to about 0.1 mm. However, the deformation of the bimetal, which is the driving force for opening and closing the contacts of the thermostat, and which occurs at a certain temperature difference, is proportional to the square of its length and inversely proportional to the thickness, so the limit of the thickness is immediately the length of the bimetal. However, there was a limit to the miniaturization of the thermostat.

[0005]

A movable conductor, which constitutes a thermostat, is provided separately from other components before assembly, has flexibility, and is processed by a fine processing technique such as photolithography. A thin film deposition means 3 such as a vacuum deposition or a sputtering is used for a part of 1 to form a thin film deposition portion 3 having a fine shape and a function of a bimetal.

Further, the substrate portions 1 and 6 on which the thin film 3 having a bimetal function is deposited are selectively removed, and the thin film portion 3 is processed into an arbitrary shape by applying a fine processing technique such as photolithography. It is taken out and utilized as an independent fine bimetal element 3.

[0007]

The movable conductor 1 forming the thermostat is, for example, a copper alloy foil having a spring property, which is finely processed into a desired shape and dimension by using a microelement processing technique such as photolithography, and one side or both sides thereof are processed. By forming the thin film layer 3 having a bimetal function in a part of it using a method such as vacuum deposition or sputtering, the shape such as thickness can be controlled in the order of micron, which is achieved by mechanical processing such as press working. It is possible to provide the movable conductor 1 having a small and lightweight bimetal function, which is unobtainable, and it is possible to reduce the size and weight of the thermostat.

Further, the base 6 for forming the bimetal thin film layer
Is used as an intermediate layer, or if only the substrate 6 is removed from the structure in which the substrate 6 is exposed on one side by a method such as plasma etching and is taken out and utilized as an independent bimetal element, both the thickness and the outer shape are extremely fine. It is possible to realize a bimetal element having a shape, and it is possible to realize an extremely small thermostat.

[0009]

Embodiments will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a movable conductor that constitutes a thermostat, which is also a base body when forming a thin film layer having a bimetal function. Generally, a thin plate of a copper alloy having a spring property such as beryllium copper or phosphor bronze is used. The thin plate can also be obtained by applying a thin film forming means such as rolling or vapor deposition or sputtering, and a fine processing technique such as photolithography.
Reference numeral 2 designates a contact portion for contacting with a fixed electric conductor to provide good electrical coupling, and silver or an alloy of silver and nickel is joined and used. Alternatively, silver or a silver alloy may be selectively formed directly on the movable conductor 1 by using a thin film forming means such as plating or vapor deposition. Reference numeral 3 indicates a thin film layer having a bimetal function.

FIG. 2 shows a partially enlarged view of an example of a thin film layer having a bimetal function. FIG. 2-1 shows a low expansion coefficient on one surface of the movable conductor 1, for example, a 36Ni—Fe alloy thin film 3-
1 on the other side, and Ni-Cr- showing a high expansion coefficient on the other side.
The Fe alloy thin film 3-2 is formed by a predetermined thickness.
The outer shape of the thin film layer can be arbitrarily formed by masking during film formation or by performing fine processing such as photolithography after film formation.

In FIG. 2-2, the low expansion alloy thin film 3-1 and the high expansion alloy thin film 3-2 are formed close to each other on only one surface of the movable conductor.

FIG. 3A shows a steady state in which the contact 2 is closed. FIG. 3-2 shows an example of an operation during heating of the movable conductor 1 arranged in the thermostat. Movable conductor 1
When a part of the bimetal thin film alloy layer portion integrated with is bent to the high expansion alloy 3-2 side, it is bent to the low expansion alloy 3-2 side due to the difference in thermal expansion during heating. Then, the contact 2 is opened and the current is cut off.

FIG. 4 shows an example of a method for producing a finely shaped bimetal element for snap operation. By applying a thin film forming technique such as sputtering on a substrate 6 formed by processing a large number of uneven surfaces of a metal thin plate such as a copper foil, for example, from the concave surface side to a low expansion alloy thin film-high expansion alloy thin film bimetal The thin film 3 is formed so as to exhibit its function. The thickness of the substrate 6 can be thinned to a level exceeding the limit of machining by means of etching or the like after the metal foil is subjected to uneven processing. After forming the thin film, a fine processing technique such as photolithography is applied to cut off the uneven surfaces to complete a disc-shaped fine bimetal element. Further, when the substrate 6 supporting the thin film having the bimetal function adversely affects the bimetal function, it can be selectively removed by using a means such as plasma etching.

[0014]

Since the present invention is constructed as described above, it has the following effects.

By integrally forming a thin film layer 3 having a bimetal function integrally with the movable conductor 1 constituting the thermostat by applying a fine processing technique, a large amount of the conventional joining and rolling type bimetal can be individually prepared. It is possible to realize a thermostat that is much more homogeneous and smaller than a machined thermostat.

By providing a large amount of bimetal thin film elements formed at one time by applying the microfabrication technology, a thermostat that is extremely homogeneous and small in size can be provided as compared with a conventional thermostat formed by individually machining the joining and rolling type bimetals. It can be realized.

[Brief description of drawings]

FIG. 1 shows an example of a movable conductor 1 provided with a thin film layer 3 having a bimetal function according to the present invention.

FIG. 2 is an enlarged view of a thin layer forming portion of a movable conductor 1 provided with a thin film layer 3 having a bimetal function according to the present invention.

FIG. 3 shows an operation example in the vicinity of a contact 2 of a thermostat having a movable conductor 1 provided with a thin film layer 3 having a bimetal function according to the present invention.

FIG. 4 shows an example of a method of manufacturing a finely shaped bimetal element for snap operation according to the present invention.

FIG. 5 is a diagram showing the vicinity of a movable conductor 1 and a fixed conductor 4 for explaining the general operation of the thermostat. Bimetal is directly used for the movable conductor 1.

FIG. 6 is a diagram showing the vicinity of a movable conductor 1 and a fixed conductor 4 for explaining the general operation of the thermostat. A bimetal 3 is arranged in the vicinity of the movable conductor 1 to indirectly move the movable conductor 1.
To open and close contact 2.

FIG. 7 is a diagram showing the vicinity of a movable conductor 1 and a fixed conductor 4 for explaining the general operation of the thermostat. The bimetal 3 is previously curved and formed so that the thermal deformation appears as a snap operation. This snap operation is performed by the movable conductor 1.
The contact 2 receives and opens and closes the contact 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 movable conductor 2 contact point 3 thin film layer having a bimetal function 3-1 low expansion alloy thin film layer 3-2 high expansion alloy thin film layer 4 fixed conductor 5 support 6 substrate

Claims (2)

[Claims] 1. A surface on which a thermostat is assembled is regulated by safety regulations such as UL, and a space insulation distance is not applied, for example, an electronic device is used by being connected to a power source secondary side of the component. In a low-voltage, low-current thermostat, a movable conductor 1, which is provided separately from other components before assembly, is a thin film deposition means such as vacuum deposition or sputtering on a flexible substrate. A thermostat formed by forming a multilayer thin film layer 3 having a bimetal function, which is deposited by using. 2. A surface of a thermostat where assembling positions of parts are regulated by safety regulations such as UL, and a space insulation distance is not applied, for example, electronic devices, parts are connected to the secondary side of power supply for use. In a low-voltage, low-current thermostat, a so-called bimetal element that is provided separately from other components before assembly and that performs deformation or snap operation by detecting temperature is a thin film such as vacuum deposition or sputtering. A thermostat, which is a multilayer thin film 3 formed by using a deposition means.