| 摘要 |
PURPOSE:To ckeck the validity of channel selection without useless power consumption by limiting automatically the light of a back light when tuning is abnormal. CONSTITUTION:When normal receiving is not executed because of detuning, no IF appears in the output (b) of a tuner 2 and only a noise component exists, so that a tuning detecting circuit 4 does not detect the IF and supplies an output signal indicating detuning state to a back light power adjusting circuit 5. The circuit 5 supplies a signal (f) for limiting the light of the back light to a back light driving circuit 6. Since the circuit 6 drives the back light by electric power lower than that of normal receiving state, the light of the back light 7 is suppressed. |
