JPH02234401A - Variable resistor - Google Patents

Abstract

PURPOSE:To prevent undesirable noises by changing the distance from a magnet provided on the tip of a screw to a magnetoresistance element while adjusting electric resistance value by driving the screw. CONSTITUTION:A magnetoresistance element 1 is provided in the position a little distant from the center of the surface of a substrate 7 of an insulator. Terminals 5 attached to the base 7 and ends of the magnetoresistance element 1 are connected by means of a lead 8. A cover 4 having a screw hole in the center is fixed to the base. Then, the screw 3 having a magnet 2 on its tip is put into the screw hole of the cover 4 and the screw 3 is driven to change a position of the magnet 2 so as to enable the resistance value of the magnetoresistance element 1 to be adjusted to desired value. Thereby, undesirable noises such as additive noises due to contact and abnormal noises due to poor contact can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a variable resistance element.

[Conventional technology]

Figure 3 is a plan view of an example of a conventional variable resistance element. A thin film resistor 11 made of carbon, metal, metal oxide, or a mixture thereof is formed as an electrical resistance material on an insulating substrate in an arc shape using various methods such as printing, plating, vapor deposition, sputtering, etc. to form. Leads 17 and electrodes 12 are attached to the ends of the thin film resistor 11 for connection to the outside. A brush 13 made of metal is provided as a third electrode for obtaining variable resistance so as to maintain contact with the thin film resistor 11. In order to move the position of the brush relative to the resistor, the knob 14 is installed and connected to the brush 13. Usually, the knob has a structure in which a smoother 15 made of Teflon or the like is placed between the knob and the brush to provide some kind of electrical insulation to the brush. A mounting base 16 and a cover (not shown) are attached to this.

[Problem to be solved by the invention]

Conventional variable resistors have the problem of undesirable noise caused by contact between the brush, which is the third electrode of the variable resistance element, and the thin film resistor, especially when handling very small voltages or currents. Ta. This noise is thought to occur because the brush and the thin film resistor are merely mechanically pressed and in contact with each other, and there is no strong bond such as bonding due to alloying of the contacting metals. especially,
The brush and thin film resistor that actually come into contact with each other are normally used with their surfaces unprotected. There is a problem in that the reliability of the resistive element becomes extremely low in such places.

Furthermore, when placed in the above environment, an insulating layer such as an oxide film is formed on the surface of the brush and thin film resistor, making it difficult to turn or move the knob to change the resistance value. There was also the problem that when moving the audio device, a large noise was generated due to poor contact, such as a scratchy sound. [Means for Solving the Problems] The variable resistance element of the present invention includes an insulating substrate and at least one magnetoresistive element provided on the surface of the substrate at a predetermined distance from the center of the substrate. at least one set of two leads connected to both ends of the magnetoresistive element and connected to an external lead terminal, a cover covering the surface of the substrate including the magnetoresistive element, and a cover at the center of the substrate. The cover includes a screw hole cut into the cover so that their centers are aligned, a screw screwed into the screw hole, and a magnet provided at the tip of the screw.

[Effect]

Semiconductors such as silicon have a general property called magnetoresistive effect, in which their electrical resistance changes when a magnetic field is applied to them. This effect occurs because the concentration of electrons and holes, which are current carriers in silicon, are spatially modulated under the influence of the applied magnetic field, and because the band structure of the semiconductor is modified by the externally applied magnetic field. It is explained that this is due to changes. The magnetoresistive effect exhibits a large value when the impurity concentration is low. However, a resistor with a large viezoresistance effect is sensitive to changes in temperature, so it is usually used after performing some kind of temperature correction. Since the change in resistivity with respect to magnetism is extremely linear, it has the characteristic of being able to accurately convert the amount of magnetism in proportion to the change in electrical resistance. The purpose of the above sensors is to dynamically convert an external mechanical signal into an electrical signal, but once the physical signal is applied, it is temporarily or permanently converted into a constant state. By adding a new structure that fixes the value, it can be used as a variable resistance element or a semi-fixed resistance element. [Example] Figure 1 (a). (b) is a front view and a sectional view taken along the line AA' of the first embodiment of the present invention.

A magnetoresistive element 1 is provided at a position slightly apart from the center of the surface of an insulating substrate 7. Terminal 5 attached to board 7
and both ends of the magnetoresistive element 1 are connected by leads 8. Cover 4, which has a screw hole in the center, can be overturned and fixed. Insert the screw 3 with the magnet 2 attached to the tip into the screw hole of the cover 4. The resistance value of the magnetoresistive element 1 changes depending on the magnetic field created by the magnet 2. Therefore, by turning the screw 3 and changing the position of the magnet 2, the resistance value of the magnetic resistance element 1 can be adjusted to a desired value, and the variable resistance element of the present invention can be obtained.

The electrical resistance value of this variable resistance element depends on the concentration of impurities used when manufacturing the magnetoresistive element. Since the magnetoresistive effect and the temperature coefficient of resistance value also change as a function of impurity concentration, these values are adjusted and used as required. Incidentally, even with the same impurity concentration, it is possible to provide an electrical resistance value suitable for any purpose by increasing or decreasing the width and depth of the magnetoresistive element, or by changing its length. The electrical resistance value is adjusted by turning the screw to change the distance between the magnet provided at the tip of the screw and the magnetic resistance element. The variable range of the electrical resistance value can be varied up to the vicinity where it does not touch the magnetoresistive element by adjusting the amount of movement of the magnet. Therefore, it is necessary to restrict the movement of the screw, and some kind of stopper may be provided. The size and shape of the screw can be arbitrary, and the same effect can be achieved with anything other than a screw that has the function of being able to stop the magnetoresistive element while applying an appropriate magnetic field. FIG. 2 is a sectional view of a second embodiment of the invention.

In this embodiment, four magnetoresistive elements 1 are provided at the same distance from the center of the surface of the insulating substrate 7 so that the plurality of magnetoresistive elements receive the same magnetic field.
Leads 8 are connected to both ends of each magnetoresistive element 1 and connected to terminals 5. Although not shown, the same cover and magnet screw as in the first embodiment are attached.

By adopting such a configuration, it is possible to change a large number of resistance elements at once. Such a variable resistance element is very useful as a collective variable resistance antibody in a device having multi-channel input/output.

Although the above embodiments have been described using only the magnetoresistive effect, similar effects can be expected even if an element such as a magnetic transistor is used as the magneto-electrical resistance conversion element. In this case, it becomes possible to use the variable resistance element as a large variable resistance element that cannot be obtained with a magnetoresistive element alone.

〔Effect of the invention〕

By using the variable resistance element of the present invention, new noise generation due to contact, which was a problem with conventional variable resistors, abnormal noise due to poor contact, and brushes and thin film resistance elements made of different materials can be avoided. It is possible to solve the problem of a decrease in the S/N ratio due to the generation of various noises such as drift due to thermoelectricity generated due to the presence of heat.

Furthermore, conventionally, various methods have been used to reduce contact resistance, but since the device is essentially used without contacting the resistor, it is not possible to achieve low reliability without using these methods. A highly variable and low antibody can be obtained. Magnetoresistive elements can be manufactured by a semiconductor manufacturing process, so they can be easily mass-produced and have stable quality. The surface of the variable resistor's brush part and thin film resistor part, which were exposed in the past, is no longer present, and the surface of the magnetoresistive element can be sufficiently protected, without the need for devising the package in the past. However, according to the present invention, passivation against any environment can be easily achieved by simply changing the thin film provided on the surface of the magnetoresistive element. Quasi-continuous attenuators using digital analog switches have existed for some time, but since controlling continuously changing electrical resistance requires a large-scale circuit, it is difficult to realize this function as a single component. was impossible. In the present invention, it is possible to install the components as individual components without taking up much space.

FIG. 3 is a cross-sectional view of the second embodiment of the present invention, and a plan view of an example of a conventional variable resistance element.

1... Magnetoresistive element, 2... Magnet, 3... Screw,
4... Cover, 5... Terminal, 7... Board, 8...
・Lead, 11... Thin film resistor, 12... Electrode, 13
...Brush, 14...Pick, 15...Subesa,
16...Photography pedestal, 17...Lead.

Claims (1)

[Claims] an insulating substrate, at least one magnetic resistance element provided on the surface of the substrate at a predetermined distance from the center of the substrate, and connected to both ends of the magnetic resistance element and connected to external extraction terminals. at least one set of two leads, a cover covering the surface of the substrate including the magnetoresistive element, and a screw hole cut into the cover so that its center is aligned with the center of the substrate; A variable resistance element comprising: a screw screwed into the screw hole; and a magnet provided at the tip of the screw.