| 摘要 |
<p>A t.v. video signal is generated by a source (10) in digital form and is transmitted to a frequency selection circuit (12) to separate the intensity signal (7) for input to a processing circuit (15) and the colour components (C) for another processing circuit (16). The intensity signals are produced in digital code for input to a D/A converter (17). - The colour component circuit generates analogue difference signals for input to a matrix (18) generating colour drive signals (r,g,b) to a video output stage (20) coupled to the c.r.t. (35). Current sensors (30-32) coupled to the drive lines deliver inputs to a regulating stage (50) that has threshold stage (75,78) that generate an output to the intensity processing stage if the current exceeds a set level. This reduces the signal amplitude without affecting the black level of the intensity signal.</p> |
