GB391006A - Improvements in and relating to apparatus for recording electrical vibrations - Google Patents

Abstract

391,006. Cathode-ray tubes. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Coolidge, W. D. ; 1480, Lenox Road, Schenectady, New York, U.S.A.) Aug. 18, 1932, No. 23211. Convention date, Aug. 18, 1931. [Class 39 (i).] Apparatus for recording electrical variations, either of a continuous character, such as audio current variations, or of short duration, comprise a cathode ray tube on which the variations are impressed and which emits rays through a slit on to a sensitized member as it is guided through a chamber exhausted of air or supplied with a low-density gas such as hydrogen. The anode is earthed and provision is made for deflecting the emitted rays accurately on to the slit. As shown, the tube is constructed with a part 3 sealed into the part 1 to constitute the anode, and the cathode comprises a straight, or small diameter coil, filament mounted in a truncated rectangular pyramid 2 and heated by a battery 6 through a rheostat 7. The operating voltage for the tube is supplied through a step-up transformer 4 and detector 5, and after modulation by the electrical variations through a transformer 12 is fed to an amplifier 9 and impressed on the cathode circuit. The rays emitted by the tube pass through a Lenard window comprising a slit in the end of the anode 3 and in a covering 27 of foil, such as aluminium foil, and fall on a film 15 guided through a chamber 16 which is exhausted or fed with hydrogen through a pipe 19. An adjustable magnet 32 acts on the rays so that they fall directly on the window. Reference has been directed by the Comptroller to Specifications 334,576, [Class 39 (i), Electric lamps, Arc &c.], and 377,272.