| 摘要 |
PURPOSE:To keep the lightness of the screen constant stably at a high speed by adopting peak detection and binarization processing so as to detect the lightness of the screen. CONSTITUTION:The light on the screen of the picture tube of a color receiver 7 is led to photodetection sections 9, 10 via a filter 8 and its output is inputted to an arithmetic section 14 via a peak detection circuit 11 and a binarizing processing section 13. The arithmetic section 14 compares the input with a value stored in advance in a memory 15 and operates a modulation of a TV signal generator 16 depending on the output. The TV signal generator 16 changes the modulation freely by an external operation signal and its output is given to an antenna terminal.
|
