US 4,207,549 AGranted

VHF Television tuner circuit with supression of undesired signals

AssigneeMurata Manufacturing Co., Ltd.

InventorsKatsuo Ito, Kazuo Kontani

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Abstract

A VHF television tuner circuit is adapted for selecting a channel from a plurality of VHF television channels and a UHF/VHF converted television channel, by mechanical selection to form a resonant circuit having electrical characteristics corresponding to the selected channel. The tuner circuit is coupled to a VHF television signal terminal and a UHF/VHF converted television signal terminal. The tuner circuit comprises a channel selection means including a first switch and a second switch each comprising movable contacts fixedly positioned on a channel selection shaft and stationary contacts corresponding to the selectable channel positions and positioned in proximity to the movable contacts for coaction therewith. The first switch comprises a movable/stationary contact combination positioned in the vicinity of the VHF television signal terminal and responsive to selection of the UHF/VHF converted channel position for being grounded for electrostatically shielding the VHF television signal terminal. The second switch comprises a movable/stationary contact combination responsive to selection of the UHF/VHF converted channel position for connecting the UHF/VHF converted television signal terminal to the radio frequency amplifier.

A VHF television tuner circuit for selecting a channel from a plurality of VHF television channels and a UHF/VHF converted television channel, by mechanical selection to form a resonant circuit having electrical characteristics corresponding to said selected channel, and thus to tune to a desired radio frequency signal, said turner circuit comprising:

first means for receiving television signals comprising VHF television signals, and producing said VHF television signals as an output thereof;
second means for receiving television signals comprising a UHF/VHF converted television signal, and producing said UHF/VHF converted television signal as an output thereof;
channel selection means for selecting one of a plurality of channel positions including VHF television channels and a UHF/VHF converted television channel corresponding to said selected channel;
a plurality of induction coils;
capacitor means;
and
radio frequency amplifying means for selectively amplifying said desired radio frequency signal;
open circuit means responsive to selection of said UHF/VHF converted channel position for establishing an open circuit at the output of said first receiving means;
means responsive to selection of one of said VHF television channel positions for connecting corresponding at least one of said plurality of induction coils,
means responsive to selection of said UHF/VHF converted channel position for connecting said second receiving means to said radio frequency amplifying means,
means responsive to selection of one of said VHF television channel positions for connecting said capacitor means to corresponding at least one of said plurality of induction coils, thereby forming said resonant circuit having electrical characteristics corresponding to said selected one of said VHF television channels, and
means positioned in the vicinity of said first receiving means and responsive to selection of said UHF/VHF converter channel position for electrostatically shielding said first receiving means.

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Abstract

Claims11