| 摘要 |
<p>An automatic control for the optimum control voltage during the line flyback time between the control electrode and the cathode of an ACT gun in a television pick-up tube. A variation in the cathode potential during the line flyback requires inter alia an adaptation of the control electrode potential. Without this adaptation a too small beam current on the target would result in an insufficient erasing action while a too large beam current would result in an inadmissible dark current with the risk of persistence upon display (afterglow). In the circuit arrangement a measurement of the beam current is effected through a specific choice of the lens pulse duration at the gun, which beam current becomes available for the erasing action on the target during the line flyback time, and through comparison with a reference value a variable pulse generator is controlled for supplying the control electrode pulse with a given pulse height during the line flyback time.</p> |
