US1740352A - Light-valve transmitter - Google Patents

Description

Dec. 117, 1929. c. F. JENKINS L'MQBEZ LIGHT VALVE TRANSMITTER Fild June 25, 1927 Patented Dec. 17, 1929 UNITED sates PATENT OFFICE CHARLES FRANCIS JENKINS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO JENKINS LABORATORIES, OF WASHINGTON, DISTRICT OF COLUMBIA, A. COR- PORATION OF THE DISTRICT OF COLUMBIA LIGHT-VALVE TRANSMITTER Application filed June 25,

v m suiting pulsating current output can be amplified in transformer coupled units, the

amplifier preferred by radio engineers.

However, as the oscillating frequencies possible with a mechanical light-chopper are very limited, and can not at all approach the 250,000 per second oscillating frequency required in radio vision and radio movies, it

has been found desirable to use a gas-cell light-valve of the type shown in my co-pending application Serial No. 200,752, filed June lVith this'and other objects in view the invention consists in the novel combination of parts hereinafter described, and more particularly pointed out in the claims.

Fig. 1 shows one preferred manner of utilizing the invention.

Fig. 2 shows a detail of the light valve of Fig. 1.

In the drawing, accompanying this specification, A is a source of light; B a condensing lens; G a motion picture film; D a.

sprocket for continuously advancing the film across the light; E a rotating lens-disc for imaging the successive frames on the picture film, and sweeping them across the gaseous light-valve F, located in front of the aperture in the cell enclosing box G. This apparatus is disclosed and claimed in United States Patent 1,559,137. H is the light-cell.

The light-valve F consists of a tubular cathode F insulated by a glass sleeve from the. enclosing anode. When alternating current circuits of suitable high frequency are connected to this cathode-anode cell, the

cathods fills with a gaseous glow which blocks the entrance to the light--cell on every positive phase, and permits thelightto pass on the opposite phase.

This action of the light-valve produces a and a gaseous light-valve located to periodi- 1927. Serial No. 201,400.

pulsating current in the output circuit of the cell, which can be amplified in transformer amplifiers.

As this type of light-valve has a frequency limit approaching infinity, it is obviously suitable for the purpose here shown.

Of course, I do not wish to limit myself to this particular valve, as any fluid light-valve which permits the whole light to pass at the. required hi h frequencies would answer.

What I c aim, is-

1. In combination, picture-image producing means, a light-sensitive cell upon which the light of said picture-image may fall, and a gaseous discharge light-valve located between said image producing means and said light-sensitive cell and operable at radio frequencies with minute currents generally available in radio work.

2. In combination, a modulated light beam, a light-sensitive cell and a gaseous lightvalve located in the path of said beam to periodically permit light access to said cell and operable at radio frequencies with minute currents generally available in radio work.

3. In combination, a motion-picture film, means for scanning successive frames of said film, -a light-sensitive cell upon which the image of said picture frames may impinge,

cally intercept the light from said film impinging on. said light-cell and operable at radio frequencies with minute currents generally available in radio work.

1. The method of'transmitting an image electrically which comprises collecting the light from successive elemental areas of the image, passing said light through a gaseous discharge light valve, and producing photoelectric currents under control of the light after it passes said valve.

The method according to claim 4, in which the light valve is continuously operated by high frequency currents.

G. The method of transmitting an image electrically at radio frequencies which comprises collecting the light from successive elemental areas of the image, passing said light through a gaseous dischargevalve, varying the intensity of the said discharge in accord- 100 ance with the high frequency current and producing photo-electric currents corresponding to the light which passes said valve.

7. In a system for electrically transmitting 5 images, the method of producing a carrier current and simultaneously modulating same by a light beam which comprises continually operating a gaseous discharge light valve by alternating current, passing a modulated .10 light beam through said valve, and projecting said. modulated beam after passing through said' valve, upon a photo-sensitive device. 4

8. In an image transmission system the 15 combination of means for analyzing succes sive elemental areas of .the image to produce a correspondingly modulated light beam, a substantially inertialess aseous discharge valve, means for continua 1y operating said 20 valve by alternating current, saidvalve being positioned in the path-of said'beam and a photo-sensitive device energized by said beam after passing through said valve.

9. A system according to the preceding 25 claim in which the light valve is of the rectifying ype In testimony whereof I have affixed my signature.

CHARLES FRANCIS JENKINS. so I

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