| 摘要 |
702,166. Television receivers. MULLARD RADIO VALVE CO., Ltd. May 9, 1952 [May 22, 1951], No. 12001/51. Drawings to Specification. Class 40 (3) In a television receiver employing a cathode-ray tube having permanent magnet focussing, when the receiver is switched off the electron beam persists due to the change held by the E.H.T. smoothing capacitor and is focussed onto a stationary point on the screen thereby damaging the phosphor and according to the present invention this is prevented by combining the main on-off switch with the brilliance control potentiometer so that when the receiver is switched off the control potentiometer is at its maximum brilliance position and the E.H.T. capacitor is discharged before the beam comes to rest due to the collapse of the sweep potential. |
