| 摘要 |
An automatic iris control for a television camera has a peak detector for producing a peak signal, representative of the illumination level on the imaging tubes, from the video signal. At least one range comparator is included to compare the peak signal with an acceptable signal range. Two command signals, indicating high out of range and low out of range conditions, are produced thereby. A digital counter responds to out of range conditions by counting upwards or downwards in dependence upon the command signals. A digital to analog converter decodes the digital output of the counter into a corresponding analog signal. A D.C. controlled iris servo opens the iris an amount proportionate to the analog signal. The light admitted through the iris is thereby contained within acceptable limits.
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