| 摘要 |
RCA 75,602 Apparatus is disclosed in a video signal processing system for automatically monitoring and controlling the blanking (black) current level of an image reproducing kinescope. A kinescope cathode output signal proportional to the level of cathode black level current conduction is induced during periodic monitoring intervals during which image signals are absent. The cathode signal is induced in response to a grid drive pulse applied during the monitoring intervals. The induced cathode signal is processed by a digital signal processing network to produce incremental bias control voltage steps for modifying the cathode bias, if necessary, in a direction to produce a desired cathode black current level. In addition, there is disclosed a special form of grid drive pulse which serves to prevent system "hunting" in the vicinity of the correct cathode bias. |
