US1944929A

US1944929A - Gaseous discharge device

Info

Publication number: US1944929A
Application number: US377937A
Authority: US
Inventors: Forest Lee De
Original assignee: GEN TALKING PICTURES CORP
Current assignee: GEN TALKING PICTURES CORP; GENERAL TALKING PICTURES Corp
Priority date: 1929-07-13
Filing date: 1929-07-13
Publication date: 1934-01-30
Anticipated expiration: 1951-01-30

Description

Jan. 30, 1934. L DE lFQREST 1,944,929

GASEOUS DISCHARGE DEVICE Filed July 13, 1929 umtoz @3M f www@ da #94A Patented Jan. 30, 1934 UNITED STATES PATENT OFFICE GASEOUS DISCHARGE DEVICE Application July 13, 1929. serial No. 377,937

8 Claims.

This invention relates in general to gas lled electron discharge devices particularly designed for photographic recording of fluctuating currents and especially for photographic sound recording.

One of the objects of this invention is the provision of a gaseous discharge device which has a longer life as compared with devices of this type now known.

Another object of this invention involves the construction of an electron discharge device which is not subject to blackening of the glass walls of the enclosing envelope;

A still further object of this invention is the la provision of a device of this type so constructed that after operation for a few hours its operation becomes stable and the amount of light given oif under any excitation is practically constant.

An additional object of this invention is to provide an electron discharge device of such construction that the cathode absorbs the gases contained within the envelope and the materials therein to a less degree than is now commonly experienced.

A.' still further object of the invention is to employ a cathode in devices of this type of tantalum and molybdenum.

These and other objects as will appear from the following disclosure are' secured by means of 80 the device of this invention.

This invention resides substantially in the combination, construction, arrangement, and relative location of parts, all as will be described in greater detail hereinafter.

Referring to the drawing- Figure 1 is a longitudinal cross-sectional view through one form of device embodying the principles of this invention;

Fig. 2 is an endrelevational view of the de- 40 vice; and

Fig. 3 is a sectional view of a modied form of device.

Heretofore any gaseous discharge devices Ias known when employed for sound recording purposes and the like have had a short useful life, usually of only a few hours duration. This short life is due chiefly to blackening of the glass .through which the light from the gas discharge passes due to the deposition on the interior of the glass containing vessel of metallic particles torn ofi by the discharge from the surface of the electrodes or electrode. It is also due in part to the gradual absorption of gases by the electrodes or by the insulating material in the tube. This invention has to do with the construction of gaseous discharge devices which avoids the aforementioned diificulties and furnishes a discharge tube which has an indefinite life, the light from which after a few hours use, attains a definite stable value and remains practically constant.

Some of the advantages of a device of this nature, which is known in the vart as a photion, are derivedfrom the fact that a cathode made of tantalum or molybdenum is employed. Other fea- A tures which produce the advantages of this invention lie in the fact that the cathode is surrounded by an envelope of insulating material and is so constructed that it may be placed very close to the rounded, smooth end of the glass vessel. In addition, the end of the cathode is polished so that it acts as a mirror, thereby somewhat increasing the illuminating efficiency ofthe discharge device.

Referring to the drawing, the elements of the discharge tube are enclosed within a glass envelope 1 which is sealed off in the usual manner at 2 after being evacuated and filled, as is well known in the art, with a suitable gas, or mixture of gases such as argon, neon, helium, and mercury. The vessel or envelope 1 has a reentrant 80 stem 3 provided with the press 4. This press supports a small glass tube 5 (exaggerated in size in the drawing) which is enclosed at its outer end by a cylinder of insulating material which overhangs the end of the glass tube. This cylinder of insulating material may be made of porcelain, isolantite, crowlite, or the like material. Isolantite is a heat treated clay product and crowlite is a heated and pressure treatedproduct made of powdered oxides of metals. Fitting within the end of the insulating sleeve 6 is the cathode 7 made'in the form of a plug which is of tantalum or molybdenum in the best form. Extending from the stem tube 3 and formed integrally therewith is a hollow tube 8 lying parallel to the central 95 axis of the envelope. Extending through this tube is a lead-in wire 11 which vconnects to a short length of platinum wire 10 sealed in the end thereof. Separated by the platinum wire 10 and encircling the insulating sleeve 6 at a short 100 distance from the end thereof is the anode or second electrode 9 inthe form of a ring. The lead wire 12 passes through the press 4 and is connected to the cathode 7 of the device. With a gas of suitable pressure within the envelope and a proper current excitation impressed across the leads 11 and 12 a luminous gas discharge is formed between the cathode and the anode up close to the end wall of vessel 1. As is well known in this art, the end of the vessel is rounded in curs between curved anode wire 14 and the cath-` ode '1. It is important that the cylinderfy of insulating material 6 in both cases iit tightly over the glass tube 5 so that an electrical discharge can never take place fromthe lead-in wires within the insulating cylinder 6. As is clear from the drawing the anode ring 9 is very close to the exterior surface of the insulating sleeve but is actually out of contact therewith. In actual construction the'cathode is within one-eighth to three-sixteenths of the interior of the glass envelope and the anode ring approximately onequarter of an inch from the forward end of the insulating sleeve 6. If desired large lead-in Wires can be employed, particularly the wire 12, so as to properly conduct away the heat from the discharge which is generated at the cathode surface. The lead-in wires, where they pass through the seals, will of course conform to any standard practice whereby an airtight connection is secured.

It has been found that tantalum and molybdenum are the best materials for the cathode. When tantalum is used there is no observable deposition upon or blackening of the glass envelope even after many hours of constant use, although when molybdenum is employed a slight blackening does occur. However, either of the above metals are greatly superior to any other material commercially available for cathode construction. In addition the absorption of the gases contained in the envelope by the cathode is much less when tantalum is used than when ordinary metals, such as nickel, iron, and the like are employed. Platinum can be advantageously employed as cathode material but the expense involved would be unnecessarily great.

From the foregoing disclosure it will be apparent that I have devised a new and novel construction in electron discharge devices which employs certain principles of construction and operation which may assume other physical forms than those disclosed in the drawing for purposes of illustration. I do not, therefore, desire to be strictly limited to the disclosure as given for purposes of illustration but rather to the scope of the appended claims.

What I seek to secure by United States Letters Patent is:

1. In a gaseous discharge photographic sound recording device of the type described, the combination comprising an envelope, a cathode within said envelope, an insulating sleeve surrounding the cathode with the exception of the end surface thereof, and an anode supported adjacent the exposed end surface of the cathode in close prox- ,lmity thereto.

2. In an electron discharge device of the type described, the combination comprising an evacuated envelope, a cathode supported within said envelope near one end thereof, an insulating sleeve encircling the cathode with the exception of the end surface thereof, and an anode supported within said envelope, said anode being in the form of a ring encircling said insulating sleeve and lying below the plane of the end surface of the cathode.

3. Ine-an electron discharge device of the type described, the combination comprising an evacuated envelope, a cathode supported within said envelope near .one end thereof, an insulating sleeve encircling the cathode with the exception of the end surface thereof, and an anode supported within said envelope, said anode being in Athe form of a ring encircling said insulating sleeve and lying below the plane of the end surface of the cathode, the end surface of said cathode being highly polished.

4. In an electron discharge device of the type described, the combination comprising an envelope having a rounded end surface, an insulating tube supported within said envelope, an insulating sleeve encircling said tube, a cathode lying within said insulating sleeve with the end surface exposed, a lead wire for said cathode passing through the tube, a hollow support within said envelope, an anode supported therefrom and encircling said sleeve, and a lead wire insulated through said hollow support and connected to said anode.

5. In an electron discharge device of the type described, the combination comprising an en-l velope having a rounded end surface, an insulating tube supported within said envelope, an insulating sleeve encircling said tube, a cathode lying within said insulating sleeve with the end surface exposed, a lead wire for said cathode passing through the tube, a hollow support within said envelope, an anode supported therefrom and encircling said sleeve, and a lead wire insulated through said hollow support and connected to said anode, said anode lying in a plane below the end surface of the cathode.

6. In an electron discharge device of the type described, the combination comprising an envelope having a rounded end surface, an insulating tube supported within said envelope, an insulating sleeve encircling said tube. a cathode 1Z0 lying within said insulating sleeve with the end surface exposed, a lead wire for said cathode passing through the tube, a hollow support within said envelope, an anode supported therefrom and encircling said sleeve, and a lead wire insulated through said .hollow support and connected to said anode, said anode lying in a plane below the end surface of the cathode, the end surface of said cathode beinghighly polished.

7. In an electron discharge sound recording de- 'll' vice of the type described, the combination comprising an evacuated vessel, an insulated cathode of tantalum having its end surface only exposed, and an anode supported very close to the exposed end of said cathode and insulated therefrom.

8. vA gaseous discharge device for photographically recording fluctuating voice currents, comprising an evacuated vessel having a spherical end wall, a cathode within said vessel having its end 14. surface very close to the spherical end wall of b the vessel, an anode adjacent the cathode, and meas for restricting the glow discharge to the end of the cathode adjacent the spherical end wall of the vessel. M.

LEE nl: FOREST.