Circuit arrangement for television receiver, in which synchronously - characters for lines - and picture change of different duration of the image signals are separated

摘要

419,441. Television. ELECTRIC & MUSICAL INDUSTRIES, Ltd., Blyth Road, Hayes, Middlesex, BROWNE, C. O., 29, Monk's Drive, West Acton, London,. and HARDWICK, J., 66, Drayton Gardens, West Drayton, Middlesex. Feb. 10, 1933, No. 4169. [Classes 40 (iii) and 40 (v).] Differences in the amplitude of synchronizing signals are reduced and ground noises and similar disturbances below a certain maximum are eliminated. Synchronizing signals applied to the grid of a valve 9 cause grid current to charge a condenser 8 sufficiently to stop the flow of anode current. Disturbances which are not of sufficient value to cause a flow of anode current are thus eliminated. The synchronizing-signals are always of sufficient amplitude to cause grid current, and the signals appearing in the anode circuit are therefore limited to a uniform amplitude. These are applied through a condenser 18 to the screen grid of a blocking oscillator 20 to start the flow of anode current which is reinforced by positive back-coupling through a transformer 23. When grid-current begins, a condenser 25 is charged and stops the anode current. A condenser 27, which has been discharged by the anode current, then begins to charge up again. The voltage, across the condenser are applied to a television apparatus through a terminal 28. The framing impulses are longer than the line-control signals, and are separated by a resistance 15 in series wth the valve 9 and shunted by a condenser 16 which has a low impedance to short impulses but a high impedance to long impulses. The framing signals are applied to a separate blocking oscillator 29.