# US 4,398,220 A · Circuit for detecting the operational state of a television receiver > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,220 A - Document ID: US4398220A - Status: Granted - Kind: A - Application number: 06/286,674 - Filed: 1981-07-24 - Granted: 1983-08-09 - Earliest claimed: 1980-09-05 - Assignees: Tokyo Shibaura Denki Kabushiki Kaisha - Inventors: Tatsuaki Satoh - Web page: https://patentgrep.com/patent/US4398220A ## CPC - H04N 17/04: for receivers - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract The present invention comprises a tuning detecting circuit, a synchronization detecting circuit, an audio noise detecting circuit, a logic circuit and a muting circuit. According to the present invention, a tuning detecting circuit detects the tuning state (i.e., proper tuning, mistuning and slight mistuning) of the local oscillator. The tuning detecting circuit receives a pair of oppositely phased signals (AFT1, AFT2) from an automatic fine tuning circuit, and generates an output signal indicative of the tuning state of the local ascillator. A synchronization detecting circuit, receiving synchronizing signals and flyback pulses, determines whether the synchronization is maintained; this circuit generates an output signal indicative of the synchronization of the synchronizing signals and the flyback pulses. An audio noise detecting circuit receiving an audio intermediate frequency (IF) signal, detects whether the IF signal includes a noise component, and generates an output signal indicative of the presence of noise. A logic circuit receives the output signals from the tuning, synchronization and audio noise detecting circuits. Depending on the operational states, the logic circuit generates either a first output signal, a second output sign, or a third output signal indicative of the operational states. ## Claims ### Claim 1 A circuit for detecting the operational states of a television receiver, said circuit comprising: tuning detecting circuit means, responsive to a detected signal from an automatic fine tuning circuit, for detecting whether a tuner is operating in a proper tuning region, a slight mistuning region, or a mistuning region, and generating a tuner detecting output signal indicative of the region of tuner operation; synchronization detecting circuit means, responsive to a synchronizing signal and a flyback pulse, for detecting whether the synchronization is maintained, and generating a synchronization detecting output signal indicative of the maintenance of synchronization; audio noise detecting circuit means, responsive to an audio intermediate frequency signal, for detecting whether said audio signal includes a noise component and generating a noise detecting output signal indicative of the presence of said noise component; and logic circuit means, responsive to said tuner detecting output signal, said synchronization detecting output signal and said noise detecting output signal, for generating a first output signal when said tuner is operating in said proper tuning region, a second output signal when said tuner is operating in said slight mistuning region, and, a third output signal when said tuner is operating in said mistuning region, wherein said first, second and third output signals represent said operational states, said logic circuit means further includes means for preventing the generation of said first and second output signals and for generating said third output signal whenever said synchronization is not maintained. ### Claim 2 (depends on 1) The circuit of claim 1 comprising: a first driving circuit means, responsive to said first output signal, for driving a first light-emitting device; and a second driving circuit means, responsive to said second and third output signals, for driving a second light-emitting device, said third output signal having alternate high and low levels for intermittently driving said second light emitting device. ### Claim 3 A circuit for detecting the operational states of a television receiver, said circuit comprising: tuning detecting circuit means, responsive to a detected signal from an automatic fine tuning circuit, for detecting whether a tuner is operating in a proper tuning region, a slight mistuning region, or a mistuning region, and generating a tuner detecting output signal indicative of the region of tuner operation; synchronization detecting circuit means, responsive to a synchronizing signal and a flyback pulse, for detecting whether the synchronization is maintained, and generating a synchronization detecting output signal indicative of the maintenance of synchronization; audio noise detecting circuit means, responsive to an audio intermediate frequency signal, for detecting whether said audio signal includes a noise component and generating a noise detecting output signal indicative of the presence of said noise component; and logic circuit means, responsive to said tuner detecting output signal, said synchronization detecting output signal and said noise detecting output signal for generating a first output signal when said tuner is operating in said proper tuning region, a second output signal when said tuner is operating in said slight mistuning region, and, a third output signal when said tuner is operating in said mistuning region, wherein said first, second and third output signals represent said operational states; and a first driving circuit means, representative to said first output signal, for driving a first light-emitting device; and a second driving circuit means, responsive to said second and third output signals, for driving a second light-emitting device, said third output signal having alternative high and low levels for intermittently driving said second light-emitting device. ### Claim 4 A circuit for detecting the operational states of a television receiver, said circuit comprising: tuning detecting circuit means, responsive to a detected signal from an automatic fine tuning circuit, for detecting whether a tuner is operating in a proper tuning region, a slight mistuning region, or a mistuning region, and generating a tuner detecting output signal indicative of the region of tuner operation; synchronization detecting circuit means, responsive to a synchronizing signal and a flyback pulse, for detecting whether the synchronization is maintained, and generating a synchronization detecting output signal indicative of the maintenance of synchronization; audio noise detecting circuit means, responsive to an audio intermediate frequency signal, for detecting whether said audio signal includes a noise component and generating a noise detecting output signal indicative of the presence of said noise component; and logic circuit means, responsive to said tuner detecting output signal, said synchronization detecting output signal and said noise detecting output signal for generating a first output signal when said tuner is operating in said proper tuning region, a second output signal when said tuner is operating in said slight mistuning region, and, a third output signal when said tuner is operating in said mistuning region, wherein said first, second and third output signals represent said operational states; and a muting circuit, responsive to said noise detecting output signal and coupled to a loudspeaker which generates sound for muting the sound when said audio signal includes said noise component. ### Claim 5 (depends on 4) The circuit of claim 4 wherein said muting circuit is also responsive to said synchronization detecting output signal to mute said sound when said synchronization is not maintained. ### Claim 6 A circuit for detecting the operational states of a television receiver, said circuit comprising: tuning detecting circuit means, responsive to a detected signal from an automatic fine tuning circuit, for detecting whether a tuner is operating in a proper tuning region, a slight mistuning region, or a mistuning region, and generating a tuner detecting output signal indicative of the region of tuner operation; synchronization detecting circuit means, responsive to a synchronizing signal and a flyback pulse, for detecting whether the synchronization is maintained, and generating a synchronization detecting output signal indicative of the maintenance of synchronization; audio noise detecting circuit means, responsive to an audio intermediate frequency signal, for detecting whether said audio signal includes a noise component and generating a noise detecting output signal indicative of the presence of said noise component; and logic circuit means, responsive to said tuner detecting output signal, said synchronization detecting output signal and said noise detecting output signal for generating a first output signal when said tuner is operating in said proper tuning region, a second output signal when said tuner is operating in said slight mistuning region, and, a third output signal when said tuner is operating in said mistuning region, wherein said first, second and third output signals represent said operational states; wherein said audio signal has a first frequency band and a second frequency band which is separate and distinct from said first band, and wherein said second band is above said first band, and said audio noise detecting circuit comprising: filter circuit means for passing said audio signal in a first frequency bandpass extending from an upper end of said first frequency band to a lower end of said second band, and for passing said audio signal in a second bandpass extending above an upper end of said second frequency band; and noise detecting means, responsive to said filter circuit, for detecting whether said audio signal includes said noise component. ### Claim 7 A circuit for detecting the operational states of a television receiver, said circuit comprising: tuning detecting circuit means, responsive to a detected signal from an automatic fine tuning circuit, for detecting whether a tuner is operating in a proper tuning region, a slight mistuning region, or a mistuning region, and generating a tuner detecting output signal indicative of the region of tuner operation; synchronization detecting circuit means, responsive to a synchronizing equal and a flyback pulse, for detecting whether the synchronization is maintained, and generating a synchronization detecting output signal indicative of the maintenance of synchronization; audio noise detecting circuit means, responsive to an audio intermediate frequency signal, for detecting whether said audio signal includes a noise component and generating a noise detecting output signal indicative of the presence of said noise component; and logic circuit means, responsive to said tuner detecting output signal, said synchronization detecting output signal and said noise detecting output signal for generating a first output signal when said tuner is operating in said proper tuning region, a second output signal when said tuner is operating in said slight mistuning region, and, a third output signal when said tuner is operating in said mistuning region, wherein said first, second and third output signals represent said operational states; and a circuit means responsive to said first output signal, for preventing the operation of said audio noise detecting circuit when said tuner is operating in said proper tuning region. ### Claim 8 A circuit for detecting the operational states of a television receiver, said circuit comprising: tuning detecting circuit means, responsive to a detected signal from an automatic fine tuning circuit, for detecting whether a tuner is operating in a proper tuning region, a slight mistuning region, or a mistuning region, and generating a tuner detecting output signal indicative of the region of tuner operation; synchronization detecting circuit means, responsive to a synchronizing signal and a flyback pulse, for detecting whether the synchronization is maintained by comparing the synchronizing signal to said flyback pulse and generating a synchronization detecting output signal indicative of the maintenance of synchronization; audio noise detecting circuit means, responsive to an audio intermediate frequency signal, for detecting whether said audio signal includes a noise component and generating a noise detecting output signal indicative of the presence of said noise component; and logic circuit means, responsive to said tuner detecting output signal, said synchronization detecting output signal and said noise detecting output signal for generating a first output signal when said tuner is operating in said proper tuning region, a second output signal when said tuner is operating in said slight mistuning region, and, a third output signal when said tuner is operating in said mistuning region, wherein said first, second and third output signals represent said operational states.