| 摘要 |
PURPOSE:To improve the video color sensitivity even at a medium/weak electric field district with simple constitution by incorporating an antenna terminal board and a booster and using a switching circuit so as to switch a TV signal inputted from an antenna only at medium/weak electric field thereby activating the booster for amplification. CONSTITUTION:A broad band high frequency amplifier 4 is inserted between an antenna 1 and a tuner 7, the amplifier 4 is provided in the antenna terminal board of a TV receiver and a switching circuit 5 and a mode switching circuit 6 are used to operator or inoperate the amplifier 4. That is, the mode switching circuit 6 is brought into the on-mode at medium/weak electric field and the circuit 5 brings the amplifier 4 into the operating state so as to amplify the broadcast signal, which is fed to the turner 7. On the other hand, the circuit 6 is brought into the off mode at a strong electric field, the circuit 5 stops the operation of the amplifier 4 and connects directly the antenna 1 and the turner 7. Thus, a picture with high quality is displayed in each electric field.
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