Turnable, Contactless Variable Resistor

Abstract

A turnable, contactless variable resistor is provided consisting of a light source and a photoconductive cell, capable of operation without producing noise and wear as distinguished from conventional turnable variable resistors having mechanical contact.

Description

BACKGROUND OF THE INVENTION:

This invention relates to a turnable, contactless variable resistor, particularly one having a photoconductive cell disposed opposite the light source, and being provided with a disk having a slit or an opening for varying the amount of light from the source to the photoconductive cell.

In general, a variable resistor has a horse shoe shaped resistance body on which a contact slide is provided; consequently, the life of the resistance body is shortened due to wear by the sliding of the contact on the resistance body.

SUMMARY OF INVENTION:

In accordance with the invention, a light source and a photoconductive cell are disposed facing each other, and therebetween is placed a disk having a large comma like opening which controls the amount of light from the light source to the photoconductive cell.

The object of this invention is to provide a turnable, contactless variable resistor having a configuration similar to that of a conventional variable resistor.

Another object of this invention is to provide a turnable, contactless variable resistor which does not generate any noise as does the conventional variable resistor.

Still another object of this invention is to provide a turnable, contactless variable resistor which does not deteriorate due to wear in the course of operation in a manner similar to that of a conventional variable resistor.

Further objects and the features of this invention will become apparent to those skilled in the art as the description thereof proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more readily described by reference to the accompanying drawings in which:

FIG. 1 is the a cross sectional view of the embodiment of this invention.

FIG. 2 is a perspective view of the embodiment of this invention.

FIG. 3 is a plan view of the turnable disk of the embodiment of this invention.

FIG. 4 is another embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to figures, disk 2 having a rotating shaft 1 on one side of the disk is disposed between an upper supporting plate 3 and a lower supporting plate 4. On the disk is provided a large comma-shaped opening whose center line is equi-distant from the center of the disk and whose width measured radially varies with the angular position of the disk in accordance with the desired output characteristic of the device. The center line of the opening is also between the centers of holes 6 and 8 on the upper supporting plate 3 and on the lower supporting plate 4. The light source 7 is placed on the hole 6 on the upper supporting plate. The leakage of light from the light source is prevented by sealing the contact between the light source 7 and the upper supporting plate by means of like material resin like material (not shown). The photoconductive cell 9 of CdS or CdSe or the like is placed beneath the hole 8 on the lower supporting disk. To prevent light leakage from the contact of the photoconductive cell and the lower supporting plate, the contact is sealed with a resin-like material (not shown). The two supporting plates are also sealed and made as one body.

Now the operation of the turnable, contactless variable resistor is described. When the rotating shaft 1 is turned, the amount of light from the light source 7 is varied by the opening 5; and the amount of the light from the light source to the photoconductive cell changes according to the area of opening. The resistance of the photoconductive cell changes with the amount of the light received. Thus, with the turn of the shaft 1, this turnable contactless variable resistor can be used as a variable resistor.

In FIG. 4 is shown another embodiment of this invention. On the upper supporting plate are disposed two holes 6 and 10. Beneath the hole 10 is another hole 11 on the lower supporting plate. On the upper hole 10 is placed another light source 12 and beneath the hole 11 on the lower supporting plate is another photoconductive cell 13. The contacts between them are sealed as in the first embodiment (Seal is not shown). With the turn of the shaft, the resistances of two photoconductive cells can be varied. Thus, this embodiment has the configuration of two contactless variable resistors.

Claims

What is claimed is:

1. A turntable, contactless variable resistor comprising:

an opaque disk having a shaft that is rotatable about a given axis;

an opaque upper supporting plate having an opening therethrough for transmitting light and a bearing for the free turning of said disk about the shaft axis;

a light source fixed to the upper supporting plate and completely on one side thereof;

an opaque lower supporting plate having an opening therethrough for transmitting light from the light source disposed coaxially with the hole on said upper supporting plate;

a photoconductive cell fixed to the opening of said lower supporting plate and completely one one side thereof; and

said disk having an opening disposed between said upper and lower supporting plates at a radial position corresponding to the radial position of the openings in said supporting plates said supporting plates being joined as one body with said one side on the outside of said body, and the conducting resistance of said photoconductive cell varying by means of a changing amount of light passing through the openings by turning said rotatable shaft.

2. A turnable, contactless variable resistor as defined in claim 1 wherein, a photoconductive cell is attached on the opening of said upper supporting plate and a light source on the opening of said lower supporting plate.

3. A turnable, contactless variable resistor as defined in claim 1 wherein, the opening of the disk is a large comma like shape, whose radial distance varies with the angular displacement of the disk about the shaft axis.

4. A turntable, contactless variable resistor as defined in claim 1 wherein:

the upper supporting plate has a second opening for transmitting light;

the lower supporting plate has a second opening located coaxially with said corresponding opening on said upper supporting plate; and

a second light source and a second photoconductive cell are attached in positions corresponding to those associated with said first light source and photoconductive cell;

whereby the resistances of the first and second photoconductive cells may be varied at the same time in response to rotation of the shaft.

5. A turntable, contactless variable resistor as defined in claim 4 wherein, the opening of the disk is a large comma-like shape, whose width measured radially varies with angular displacement of the disk about the shaft axis.