Photoelectric, red-sensitive cell, the cathode of an approximately monomolecular, practically invisible thin skin photoelectric material on a metal layer

摘要

309,224. General Electric Co., Ltd., and Campbell, N. R. Jan. 7, 1928. Addition to 306,996. Vacuum tubes.-A photo-electric cell having a red-sensitive cathode according to the parent Specification, is filled with hydrogen. Constancy of the hydrogen filling may be ensured by providing a palladium tube in the cell. The support for the sensitive film is of a metal other than silver or platinum, and is preferably copper or zinc. A preliminary layer of silver, formed on the bottom of the cell, is washed, dried, and heated to 100‹ C. for 15 minutes. The cell is then supported with the silvered coating vertical and is filled with a coppering solution. A current of about 2 milliamperes per square centimetre is passed through the solution for 15 minutes, with a copper wire as anode and the silvered coating as cathode. The conditions should be adjusted so that the copper surface is a matt chocolate brown. The cell is washed, dried, and baked for a few minutes at 300‹ C. so as to oxidize the surface of the copper. The film of potassium is formed as described in the parent Specification, and hydrogen is admitted. The coppering solution is formed by preparing freshly precipitated copper carbonate by adding a solution of 400 grams of crystallized copper sulphate in 2 litres of water to a solution of 100 grams of anhydrous potassium carbonate in 1 litre of water. The mixed solution is allowed to stand for one hour and the precipitate is filtered off and washed. The precipitated copper carbonate is gradually added in excess to 60 grams of acid potassium tartrate dissolved in 1 litre of boiling water. The solution is filtered and allowed to stand for several days until the deposition of a blue precipitate ceases or becomes very slow. Specification 291,763 also is referred to.