US1298457A - Variable resistance. - Google Patents

Description

UNITED STATES PATENT OFFICE.

THEODORE W. CASE, OF BCIPIO, NEW YORK.

VARIABLE nnsrs'rmvcn.

Specification 01 Letters Patent.

No Drawing. Original application filed February 19, 1817, Serial No. 149,704. Divided and this application filed May 16, 1917.

To all whom it may. concern:

Be it known that I, THEODORE W. -CASE, a citizen of the United States of America, and resident of Scipio, in the County of Cayuga, in the State of New York, haveinvented new and useful Improvements in Variable Rcsistances, of which the following is a full, clear, and exact description.

his invention relates to certain improvements in new materials or compounds showing a variable resistance, and specificallycontemplates a material as an element of an electric circuit, subject to the condition that variations in light produce a corresponding variation in the electrical resistance of the element, thereby effecting a change of current in accordance with variations of light intensity to which the element is exposed, and is a division'of my copending application, Serial No. 149,704, filed February 19, 1917, which application contains the claims to a compound of lead, antimony and sulfur for the purpose set forth herein.

The object, therefore, of the invention is the productionof a material or compound adapted to form a portion of an electric circuit or conductor, the resistance of which diminishes as the intensity of the light to which it is exposed increases.

I have discovered that a material consisting of or containing lead, antimony and sulfur in varied proportions, or a compound of said elements, can be utilized as a portion of an electric circuit, and that its resistance to the passage of currents through said circuit varies under the influence of light to effect a change of current in accordance with the intensity of the light rays to which the substance is subjected, and that a material consisting of lead, antimony and sulfur is peculiarly efficient for this purpose and ig'hly sensitive to variation of light intensity due to the fact that it is practically a non-conductor of electricity in absolute dark and the ratio of change or percentage change of its resistance to the passage of an electric current under variations of light intensity is very great.

An interesting phenomenon of the invention consists in the fact that the electrical resistance of the material specified is varied byrays of light invisible to the human eye, such variation of current being readily demonstrated and measured by known appa- Serial No. 189,111.

. any suitable way for contact with each other and exposure to light rays.

The invention is adapted for and may be applied to various uses, as, for instance, in 1 the Bell photophone, and I, therefore, desire to broadly claim the same without restriction as to the method, manner or condition of use and without limitation as to the addition of any other elements to the material or compound so lon as the same do not destroy the utility of t e material for this purpose, and I desire to claim the material for use with both direct and alternatin current, and the expression light rays, as used in the specification and claims hereof is deemed to mclude both visible and invisible ra s.

What claim is:

1. A resistance element formed of a material containing lead, antimony and sulfur.

2. An element adapted to var its electrical resistance in accordance with the intensity of light to which it is exposed, and comprising lead, antimony and sulfur.

3. An electric circuit having a portion supported for exposure to light rays, such portion formed of a maternal containing lead, antimony and sulfur.

4. A resistance element adapted to be interposed in an electric circuit for exposure to light rays comprising a series of electrically connected pieces or a single crystal of material containing lead, antimony and sulfur.

In witness whereof I have hereunto set my hand this 8th day of May 1917.

THEODORE W. CASE.