Local oscillation device for a television receiver set

Claim 2

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency; means for supplying the output frequency from said sweeping oscillator to a frequency converter which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor at a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signals from said mixer when a predetermined frequency difference exists between the output frequency of said harmonics generator and the output frequency of the sweeping oscillator; means coupled to said band pass filter for deriving marker sigNals corresponding to the respective channel positions from the output of said band pass filter; key means coupled to said sweep oscillator through a control means for producing said start-of-sweep signal; means for selecting a desired channel with the aid of said marker signals after the start-of-sweep and for stopping the sweep through said control means; and an automatic frequency control (AFC) circuit for maintaining the output frequency of said sweeping oscillator constant after the stop-of-sweep.

Claim 3

The local oscillation device for a television receiver set as set forth in claim 1 wherein said band pass filter has a 2 MHz pass band.

Claim 4

The local oscillation device for a television receiver set as set forth in claim 1 wherein said means for deriving the marker signals includes means for deriving signals corresponding to odd numbered ones of even numbered ones of the beat signals as said marker signals correspond to the respective channels.

Claim 5

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency; means for supplying the output frequency from said sweeping oscillator to a frequency converter which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor of a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signals from said mixer when a predetermined frequency difference exists between the output frequency of said harmonics generator and the output frequency of the sweeping oscillator; means cupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter; channel selection means including a digit key for supplying said start-of-sweep signal to said sweep oscillator through a control means, a counter for sequentially counting said marker signals and means for presetting a numeric value corresponding to a channel number to be selected simultaneously with the channel selection operation for producing a signal for stopping the sweep of said sweeping oscillator when the count of said counter corresponds to said preset value; and an automatic frequency control (AFC) circuit for maintaining the output frequency of said sweeping oscillator constant after the stop-of-sweep.

Claim 6

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency; means for supplying the output frequency from said sweeping oscillator to a frequency converter which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor of a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signals from said mixer when a predetermined frequency difference exists between the output frequency of said harmonics generator and the output frequency of the sweeping oscillator; means cupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter; channel selection means including a digit key for supplying said start-of-sweep signal to said sweep oscillator through a control means, a counter for sequentially counting said marker signals and means for presetting a numeric value corresponding to a channel number to be selected simultaneously with the channel selection operation for producing a signal for stopping the sweep of said sweeping oscillator when the count of said counter corresponds to said preset value; and an automatic frequency control (AFC) circuit for maintaining the output frequency of said sweeping oscillator constant after the stop-of-sweep.

Claim 7

The local oscillator device for a television receiver set as set forth in claim 4 wherein said channel selection means further includes a memory circuit and a comparator circuit, said memory circuit storing the channel number to be selected by the operation of the digit key, said comparator circuit comparing the count of said counter with the stored content of said memory circuit for producing said stop-of-sweep signal when both values coincide.

Claim 8

The local oscillation device for a television receiver set as set forth in claim 4 further including an indicator circuit for indicating the channel number selected, the indicator circuit indicating the channel number corresponding to the count of said counter.

Claim 9

The local oscillation device for a television receiver set as set forth in claim 4 wherein said channel selection means includes a digit key and a programmable counter, the count of said programmable counter being set to the numeric Value corresponding to the channel to be selected by said digit key, said stop-of-sweep signal being produced when the count of said counter reaches the set count of said programmable counter.

Claim 10

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency; means for supplying the output frequency from said sweeping oscillator to a frequency converter which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor at a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signals from said mixer when a predetermined frequency difference exists between the output frequency of said harmonics generator and the output frequency of the sweeping oscillator, means coupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter, a function key coupled to said sweep oscillator through a control means for producing said start-of-sweep signal, an AND circuit for producing an output only when said marker signal and a tuning signal from the TV receiver set occur concurrently, means in response to the output of said AND circuit to stop the sweep of said sweeping oscillator, and and AFC circuit for maintaining the output frequency of said sweeping oscillator constant after the stop-of-sweep.

Claim 11

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency; means for supplying the output frequency from said sweeping oscillator to a frequency converter which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor at a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signals from said mixer when a predetermined frequency difference exists between the output frequency of said harmonics generator and the output frequency of the sweeping oscillator, means coupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter, a function key coupled to said sweep oscillator through a control means for producing said start-of-sweep signal, an AND circuit for producing an output only when said marker signal and a tuning signal from the TV receiver set occur concurrently, means in response to the output of said AND circuit to stop the sweep of said sweeping oscillator, and and AFC circuit for maintaining the output frequency of said sweeping oscillator constant after the stop-of-sweep.

Claim 12

The local oscillation device for a television receiver set as set forth in claim 8 wherein said band pass filter has a 2 MHz pass band.

Claim 13

The local oscillation device for a television receiver set as set forth in claim 8 wherein said means for deriving the marker signals includes means for deriving marker signals corresponding to the respective channels from odd numbered or even numbered ones of said beat signals.

Claim 14

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency; means for supplying the output frequency from said sweeping oscillator to a frequency converter which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor at a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signals from said mixer when a predetermined frequency difference exists between the output frequency of said harmonics generator and the output frequency of the sweeping oscillator, means coupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter, channel selection means for producing a first stop-of-sweep signal including a digit key for producing said start-of-sweep signal, a counter for sequentially counting said marker signals and means for presetting the numeric value corresponding to the channel number to be selected simultaneously with the channel selection operation for stopping the sweep of said sweeping oscillator when the count of said counter corresponds to said preset value, means for producing said start-of-sweep signal through the operation of a function key, an AND circuit for producing an output only when said marker signal and a tuning signal from the TV receiver set occur concurrently, means for producing a second stop-of-sweep signal for stopping the sweep of said sweeping oscillator in response to the output of said AND circuit, and an automatic frequency control (AFC) circuit for maintaining the output of said sweeping oscillator constant after the stop-of-sweep.

Claim 15

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency; means for supplying the output frequency from said sweeping oscillator to a frequency converter which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor at a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signals from said mixer when a predetermined frequency difference exists between the output frequency of said harmonics generator and the output frequency of the sweeping oscillator, means coupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter, channel selection means for producing a first stop-of-sweep signal including a digit key for producing said start-of-sweep signal, a counter for sequentially counting said marker signals and means for presetting the numeric value corresponding to the channel number to be selected simultaneously with the channel selection operation for stopping the sweep of said sweeping oscillator when the count of said counter corresponds to said preset value, means for producing said start-of-sweep signal through the operation of a function key, an AND circuit for producing an output only when said marker signal and a tuning signal from the TV receiver set occur concurrently, means for producing a second stop-of-sweep signal for stopping the sweep of said sweeping oscillator in response to the output of said AND circuit, and an automatic frequency control (AFC) circuit for maintaining the output of said sweeping oscillator constant after the stop-of-sweep.

Claim 16

The local oscillation device for a television receiver set as set forth in claim 11 further comprising a control circuit including a set terminal, reset terminal and first and second output terminals and a control signal generator circuit for said sweeping oscillator, the signals from said function key and said digit key being applied to said set terminal, said first and second stop-of-sweep signals being applied to said reset terminal of said control circuit, the output from said first output terminal of said control circuit being applied to the input terminal of said control signal generator circuit to activate it, and the output from the second output terminal of said control circuit being applied to said AFC circuit to activate the AFC circuit simultaneously with the stop-of-sweep.

Claim 17

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency, means for supplying the output frequency from said sweeping oscillator to a frequency convertor which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor at a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signal from said mixer when a predetermined frequency difference exists between the output frequency of said harmonic generator and the output frequency of said sweeping oscillator, means coupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter, channel selection means including a digit key for producing said start-of-sweep signal, a counter for sequentially counting said marker signals and means for presetting the numeric value corresponding to the channel selection operation for stopping the sweep of said sweeping oscillator when the count of said counter corresponds to said preset value, and a digital automatic frequency control (AFC) circuit for counting the number of waves constituting the output signals from said band pass filter after the stop-of-sweep and controlling the output frequency of said sweeping oscillator with said count so as to maintain the output frequency of said band pass filter at a predetermined frequency.

Claim 18

A local oscillation device for a television receiver set comprising: a harmonics generator for producing simultaneously a plurality of frequency spectra having a frequency separation equal to the frequency separation among a plurality of channels, the frequency of each spectrum being an integral multiple of said separation frequency; a sweeping oscillator for initiating its sweep in response to a start-of-sweep signal and varying its oscillation frequency, means for supplying the output frequency from said sweeping oscillator to a frequency convertor which mixes said output frequency with a television broadcasting wave frequency to obtain a predetermined video intermediate frequency, said output frequency to be supplied to the frequency convertor at a tuning condition not an integral multiple of said separation frequency; a mixer coupled to said harmonics generator and said sweeping oscillator for obtaining beat signals produced between the frequency of said harmonics and the frequency of said sweep generator; a band pass filter coupled to said mixer for deriving beat signal from said mixer when a predetermined frequency difference exists between the output frequency of said harmonic generator and the output frequency of said sweeping oscillator, means coupled to said band pass filter for deriving marker signals corresponding to the respective channel positions from the output of said band pass filter, channel selection means including a digit key for producing said start-of-sweep signal, a counter for sequentially counting said marker signals and means for presetting the numeric value corresponding to the channel selection operation for stopping the sweep of said sweeping oscillator when the count of said counter corresponds to said preset value, and a digital automatic frequency control (AFC) circuit for counting the number of waves constituting the output signals from said band pass filter after the stop-of-sweep and controlling the output frequency of said sweeping oscillator with said count so as to maintain the output frequency of said band pass filter at a predetermined frequency.