GB446547A - Improvements relating to relaxation oscillation generators for use with cathode ray tubes - Google Patents

Abstract

446,547. Generating circuits using gas-discharge tubes; television. RADIOAKT.-GES. D. S. LOEWE, 10, Wiesenweg, Steglitz, Berlin. Feb. 11, 1935, Nos. 4317 and 4318. Convention dates, Feb. 12, 1934 and April 19, 1934. [Classes 40 (iii) and 40 (v)] In a relaxation oscillator, the relaxation condenser is shunted by an auxiliary gas discharge tube whose ignition potential is greater than that of the main discharge tube before the cathode of the latter has reached its operating temperature, and whose quenching potential is greater than the ignition potential of the heated main tube. The auxiliary tube has a cold cathode or one with substantially no thermal inertia and a discharge passes therethrough until the main tube has reached operating temperature thus protecting the relaxation condenser from excess voltages. The discharge current in the auxiliary tube may be used to disable an associated cathode ray tube until scanning voltages are being generated, to prevent burning of the screen. Thus the auxiliary tube 5, Fig. 1, connected in parallel with the main tube 4 and relaxation condenser 3 is connected in series with a relay winding 6 which when energized opens the anode circuit 7, 8 of an associated cathode ray tube. In a second embodiment, Fig. 2 (not shown), the discharge current from two auxiliary tubes connected to two associated relaxation oscillators traverses a common resistance to produce a blocking bias for the control electrode of the cathode ray tube. In a similar embodiment, Fig. 3, an auxiliary tube 19 is common to two relaxation oscillators 2, 3, 4 and 2<1>, 3<1>, 4<1>, a common tubular cathode 21 co-operating with separate anodes 20, 20<1>. The commencement of a discharge between these electrodes initiates a discharge current between the electrode 21 and a further electrode 22 which traverses a biassing resistance 23 to block the control electrode 15 of the cathode ray tube. The Specification as open to inspection under Sect. 91 comprises also a circuit in which the auxiliary discharge tube is arranged to produce relaxation oscillations until the main tube is functioning. This subject-matter does not appear in the Specification as accepted.