| 摘要 |
<p>A device for adjusting brightness and contrast of a cathode ray tube in a television receiver, which comprises an insertion circuit (2) for inserting first and second reference signals Pc and PY into the video signals, a variable amplifier (5) for amplifying video signals, a gain adjusting circuit which detects the first reference signal Pc from the output of variable amplifier (5) and which adjusts the gain of the variable amplifier (5) so that the intensity of the detected signal reaches a predetermined value, a circuit which supplies the output of variable amplifier (5) to a cathode ray tube (11), a brightness adjusting circuit which detects the second reference signal PY and adjusts the brightness of the cathode ray tube (11) depending upon the intensity of the thus detected second reference signal PY, adjusting circuits (21), (23) for changing the levels of the first and second reference signals Pc, PY, and a constantly multiplying circuit (24) which so multiplies the level of the second reference signal PY as to become a constant number of times as great as the level of the first reference signal Pc. The device of the invention can adjust the contrast and brightness independently of each other.</p> |
