JPS63310102A - Variable resistor and variation in its resistance - Google Patents

Abstract

PURPOSE:To eliminate a reduction in the performance due to the deterioration of a contact for a long term and to control an amount of a change in a resistance value by installing a transition means which can shift a state between a superconducting state and a normal conducting state with regard to a superconducting material used as a resistance material. CONSTITUTION:Superconducting materials 1-4 are used for a resistance material; a temperature of the superconducting materials 1-4 is controlled near a critical temperature or a magnetic field to be exerted on the superconducting materials 1-4 is controlled near a critical magnetic field; in this manner, a transition between a superconducting state and a normal conducting state is controlled, and a change in a resistance value in each state is utilized. If heaters 8-11 in parts to heat the superconducting materials 1-4 partially or a power supply of a coil to change the magnetic field are controlled, it is possible to control a resistive region and to change the resistance value of all resistors. By this setup, it is possible to prevent an error in the resistance value or a noise due to the deterioration of a contact between a brush and the resistance material; it is possible to obtain a long-life variable resistor.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a resistor which is an electric circuit element, and is particularly suitable for preventing performance deterioration over a long period of time and for automatically controlling its resistance value. This paper relates to a variable resistor and a method of varying its resistance.

[Conventional technology]

As described in the Electrical Engineering Handbook, conventional variable resistors have one electrode connected to the end of the resistive material, the other electrode connected to a brush, and the brush connected to the end of the resistive material while touching it. By moving the resistance material and changing its effective length, the resistance value was changed.

[Problem that the invention seeks to solve]

In the above-mentioned conventional variable resistor, the brush moves on the resistance material while touching it, so the contact deteriorates due to friction between the brush and the resistance material and current flowing through the contact, resulting in poor contact between the brush and the resistance material. This causes problems such as errors in resistance values and generation of noise. Further, no particular consideration was given to automatically controlling the resistance value. SUMMARY OF THE INVENTION An object of the present invention is to provide a variable resistor and a method for varying the resistance thereof, which does not deteriorate performance due to contact deterioration over a long period of time and can control the amount of change in resistance value.

[Means for solving problems]

The above purpose is to use a superconducting material as a resistive material and to control the temperature of the superconducting material near the critical temperature, or to control the magnetic field applied to the superconducting material near the critical magnetic field. This can be achieved by controlling the transition of and utilizing changes in resistance in each state.

[Effect]

FIG. 3 shows an outline of a typical example of the resistivity characteristics with respect to temperature of a superconducting material. A superconducting material has a conductivity, that is, an electrical resistance of zero below a critical temperature Tc1. On the other hand, above the critical temperature Tcz, it has a finite resistivity ρ. Therefore, if the temperature of the superconducting material is controlled near the critical temperature, its resistance value can be changed without the need for a brush. That is, superconducting materials become perfect conductors at temperatures below T c 1.

On the other hand, at temperatures above TC2, it acts as a resistance. Therefore, by cooling the entire superconducting material to below TCI and partially heating it to a temperature above Tea, it is possible to partially impart resistance.

In addition, similar to temperature, the magnetic field applied to superconducting materials has the property that when a magnetic field of a certain temperature or higher is applied, the superconducting state transitions to the normal conducting state. A similar effect can be obtained by controlling the Furthermore, by controlling the power source of the heater in the part that heats the superconducting material or the coil that changes the magnetic field, the region with resistance can be controlled and the resistance value of the entire resistor can be changed. However, if the entire resistor is made of superconducting materials of - pair, there will be problems with heat transfer and magnetic shielding.
Since it is difficult to accurately control the resistance value, it is difficult to control the temperature and temperature of each superconducting material by connecting multiple superconducting materials in series.
It is desirable to ensure the accuracy of the resistance value by independently controlling the magnetic field.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Superconducting material Al, superconducting material B2. Superconducting material C3 and superconducting material D4 are connected in series. Superconducting material A, B
, C, and D, heaters A8 . Heater B9. Heater C10, heater Dll
Place.

A substrate 5 containing superconducting materials A, B, C, and D and a heater A.

B, C, and D are all enclosed in a constant temperature bath 6. The constant temperature bath 6 is
The temperature is set so that superconducting materials A, B, C, and D are maintained in a superconducting state. A temperature control circuit is connected to heaters A, B, C, and D. The output of the heater is set so that the superconducting material in the portion where the heater circuit is turned on is heated by the heater and thereby transitions to a normal conductive state. Superconducting materials A, B, C,
D has a uniform width and a length ratio of 1:2:3:5. The resistance value of a superconducting material when it is in a normal conductive state is proportional to its length. Therefore, the resistance ratio when each superconducting material transitions to a normal conductive state is 1:2:3:5. If each superconducting material is appropriately transitioned to a normal conductive state and the resistances are combined, if the minimum resistance value is 1Ω, then 1
Resistance values up to ~10Ω can be obtained. In order to realize a resistance value other than this, it is sufficient to connect a plurality of such resistor sets. Furthermore, by connecting an automatic control circuit to the control circuit of the power source of the heater, the resistance value of the entire resistor can be automatically controlled.

A second embodiment of the present invention will be described with reference to FIGS. 4 and 5. Heaters A and B in the first embodiment.

C and D are respectively coil A13. Replace coil B14° with coil C15 and coil D1G. Turn on the power to the coil
The number of turns of the coil and the single current flowing through the coil are set so that the magnetic field in the n portion exceeds the critical magnetism of the superconducting material.

〔Effect of the invention〕

According to the present invention, since the variable resistor does not require a brush, it is possible to prevent errors in resistance value and generation of noise due to deterioration of the contact between the brush and the resistance material. It is possible to provide a variable resistor with a long life and a method for varying its resistance.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional plan view of a variable resistor according to a first embodiment of the present invention, FIG. 2 is a partially cross-sectional elevation view, and FIG. 3 is a temperature characteristic of resistivity of a superconducting material. FIG. 4 is a partially cross-sectional plan view of a variable resistor according to a second embodiment of the present invention, and FIG. 5 is a partially cross-sectional elevation view. 1... Superconducting material A, 2... Superconducting material B, 3... Superconducting material C14... Superconducting material D, 5... Substrate, 6...
・Thermostatic oven, 7... Connection terminal, 8... Heater A, 9.
... Heater B, 10... Heater C111... Heater D, 12... Support leg, 13... Coil A, 14 ・
...Coil B, 15-...Coil C116...Coil D. Agent: Patent attorney Masaru Ogawa p.2. Dormitory 1 Eye 3 Color Te+ Tcz Hen Arashi

Claims (1)

[Claims] 1. In a variable resistor comprising a resistive material and a terminal, the resistive material is a superconducting material, and a transition means for causing the superconducting material to transition between a superconducting state and a normal conducting state. A variable resistor characterized by having. 2. The variable resistor according to claim 1, wherein the transition means is heat generation means. 3. The variable resistor according to claim 1, wherein the transition means is a magnetic field generation means. 4. A variable resistor consisting of a resistive material and a terminal, in which a superconducting material is used as the resistive material, and the resistance value is changed by changing the state between a superconducting state and a normal conducting state. How to change the resistance of the device. 5. A method of varying the resistance of a variable resistor according to claim 4, characterized in that the overall resistance value is varied by partially varying the temperature of the superconducting material. 6. A method of varying the resistance of a variable resistor according to claim 4, characterized in that the overall resistance value is varied by partially varying the magnetic field applied to the superconducting material. 7. In claim 4, the superconducting material is divided into a plurality of parts, and the overall resistance value is changed by independently controlling the temperature of each superconducting material or the magnetic field applied to each superconducting material for each divided region. A method for varying the resistance of a variable resistor.