Color subcarrier phase shift circuit for color television receiver

Claim 2

A color subcarrier phase shift circuit comprising: a. a positive phase shift circuit which receives a first color subcarrier signal ao and operatingly shifts said first subcarrier signal ao by a specific angle theta in phase, to produce a signal bo, said positive phase shift circuit comprising a capacitor and a resistor connected together in series, said first color subcarrier signal being applied across the series circuit of said capacitor and said resistor and said signal bo being derived across said resistor; b. a phase inversion circuit which receives said first color subcarrier signal ao and said signal bo and operatingly inverts said signals ao and bo to produce inverted signals a1 and b1 having phases inverted with respect to those of said signals ao and bo, respectively; c. a first signal composite circuit applied with a first controlled signal and receiving said signals bo and a1, said first control signal applied to said first composite circuit controlling the input distribution ratio of the magnitudes of said input signals bo and a1, said first signal composite circuit operatingly combining vector-wise said input signals a1 and bo thus controlled in their magnitudes; and d. a second signal composite circuit applied with a second control signal and receiving said signal b1 and one of said signals ao and a1, said second control signal applied to said second signal composite circuit controlling the input distribution ratio of the magnitudes of said input signal b1 and one of said signals ao and a1, said second signal composite circuit operatingly combining vector-wise said input signals b1 and one of said signals ao and a1 thus controlled in their magnitudes; whereby second and third color subcarriers each having a specific phase relation with respect to the first color subcarrier are produced.

Claim 3

A color subcarrier phase shift circuit comprising: a. an emitter follower circuit supplied with a first color subcarrier signal ao and provided, at the emitter thereof, with an output terminal from which the color subcarrier signal ao is delivered at a low output impedance; b. a positive phase shift circuit connected to the output terminal of said emitter follower circuit for shifting the phase of said color subcarrier signal aO supplied from the output terminal by a specific angle theta to thereby produce a signal bo, said positive phase shift circuit comprising a capacitor and a resistor connected together in series, the capacitor having an input terminal for receiving said first color subcarrier signal ao and an output terminal connected to a node between said capacitor and said resistor for producing said signal bo, the other end of the resistor being connected to ground; c. a pair of differential amplifiers, one input terminal of one of the pair of differential amplifiers being connected to said positive phase shift circuit and one input terminal of the other of the pair of differential amplifiers being connected with the output terminal of said emitter follower circuit, the remaining input terminals of the pair of differential amplifiers being connected together and supplied thereto with a reference voltage, whereby said signals bo and ao are inverted to obtain signals b1 and a1, respectively; d. a first signal composite circuit which receives said signals bo and a1 to combine vector-wise said signal bo with said signal a1 and a voltage for controlling the input distribution ratio of the magnitudes of said signals supplied to the first signal composite circuit; and e. a second signal composite circuit which receives said signal b1 and one of said signals ao and a1 to combine vector-wise said signal b1 with one of said signals ao and a1 and a voltage for controlling the input distribution ratio of the magnitudes of said signals supplied to the second signal composite circuit; whereby second and third color subcarriers, each having a specific phase relation with respect to the first color subcarrier, are produced.

Claim 4

A color subcarrier phase shift circuit comprising: a. an emitter follower circuit supplied with a first color subcarrier signal ao and provided, at the emitter thereof, with an output terminal from which the color subcarrier signal ao is delivered at a low output impedance; b. a positive phase shift circuit connected to the output terminal of said emitter follower circuit for shifting the phase of said color subcarrier signal aO supplied from the output terminal by a specific angle theta to thereby produce a signal bo, said positive phase shift circuit comprising a capacitor and a resistor connected together in series, the capacitor having an input terminal for receiving said first color subcarrier signal ao and an output terminal connected to a node between said capacitor and said resistor for producing said signal bo, the other end of the resistor being connected to ground; c. a pair of differential amplifiers, one input terminal of one of the pair of differential amplifiers being connected to said positive phase shift circuit and one input terminal of the other of the pair of differential amplifiers being connected with the output terminal of said emitter follower circuit, the remaining input terminals of the pair of differential amplifiers being connected together and supplied thereto with a reference voltage, whereby said signals bo and ao are inverted to obtain signals b1 and a1, respectively; d. a first signal composite circuit which receives said signals bo and a1 to combine vector-wise said signal bo with said signal a1 and a voltage for controlling the input distribution ratio of the magnitudes of said signals supplied to the first signal composite circuit; and e. a second signal composite circuit which receives said signal b1 and one of said signals ao and a1 to combine vector-wise said signal b1 with one of said signals ao and a1 and a voltage for controlling the input distribution ratio of the magnitudes of said signals supplied to the second signal composite circuit; whereby second and third color subcarriers, each having a specific phase relation with respect to the first color subcarrier, are produced.

Claim 5

A color subcarrier phase shift circuit supplied with a first color subcarrier signal ao whose phase is coincident with that of a B-Y subcarrier comprising: a. a first phase shift circuit supplied with the first color subcarrier signal ao for positively shifting the phase of said input subcarrier signal ao by a specific phase lead angle theta less than 90* to thereby produce a shifted signal bo, b. a second phase shift circuit supplied with the signals ao and bo for inverting the phases of said signals supplied thereto, to thereby produce signals a1 and b1 inverted with respect to the signals ao and bo, respectively; c. first and second signal composite circuits each supplied with two signals for operatingly combining vector-wise the two signals supplied thereto together, said first signal composite circuit being supplied with said signals a1 and bo and said second signal composite circuit being supplied with said signal b1 and one of said signals ao and a1, respectively; and d. control means for supplying first and second control signals to said first and second signal composite circuits so as to control the input distribution ratio of the magnitudes of the two signals supplied to each said signal composite circuits, respectively, whereby a second color subcarrier signal which has a leading phase angle of about 90* coincident with the phase of an R-Y subcarrier and a third color subcarrier signal which has a lagging phase angle of about 123* coincident with the phase of a G-Y subcarrier are obtained from said first and second signal composite circuits, respectively.

Claim 6

A color subcarrier phase shift circuit supplied with a first color subcarrier signal ao whose phase is coincident with that of a B-Y subcarrier comprising: a. a first phase shift circuit supplied with the first color subcarrier signal ao for positively shifting the phase of said input subcarrier signal ao by a specific phase lead angle theta less than 90* to thereby produce a shifted signal bo, b. a second phase shift circuit supplied with the signals ao and bo for inverting the phases of said signals supplied thereto, to thereby produce signals a1 and b1 inverted with respect to the signals ao and bo, respectively; c. first and second signal composite circuits each supplied with two signals for operatingly combining vector-wise the two signals supplied thereto together, said first signal composite circuit being supplied with said signals a1 and bo and said second signal composite circuit being supplied with said signal b1 and one of said signals ao and a1, respectively; and d. control means for supplying first and second control signals to said first and second signal composite circuits so as to control the input distribution ratio of the magnitudes of the two signals supplied to each said signal composite circuits, respectively, whereby a second color subcarrier signal which has a leading phase angle of about 90* coincident with the phase of an R-Y subcarrier and a third color subcarrier signal which has a lagging phase angle of about 123* coincident with the phase of a G-Y subcarrier are obtained from said first and second signal composite circuits, respectively.

Claim 7

A color subcarrier phase shift circuit in accordance with claim 3 in which each of said signal composite circuits comprises two differential amplifiers, and said control means supplies to the respective differential amplifiers said first and second control voltages, respectively for controlling said input signal magnitude distrubution ratio.

Claim 8

A color subcarrier phase shift circuit in accordance with claim 3 in which the first phase shift circuit comprises a capacitor and a resistor connected in series together, said phase shift circuit having a pair of output terminals provided at the both ends of said resistor for producing the shifted signal bo and a pair of input terminals provided at both ends of said series circuit for receiving said input subcarrier signal ao.

Claim 9

A color subcarrier phase shift circuit according to claim 3, wherein said second signal composite circuit is supplied with said signals b1 and a1 when the phase lead angle theta is within 57* to 90* .

Claim 10

A color subcarrier phase shift circuit according to claim 3, wherein said second signal composite circuit is supplied with said signals b1 and ao when the phase lead angle theta is less than or equal to 57*.

Claim 11

A color subcarrier phase shift circuit according to claim 3, wherein the input signal magnitude distribution ratio of said first signal composite circuit is controlled by said first control signal in such a manner that the magnitude of said signal a1 is changed to a certain value, which when combined vector-wise with said signal bo, produces a first composite signal output having a leading phase angle of about 90* with respect to said signal ao, and wherein the input signal magnitude distribution ratio of said second signal composite circuit is controlled by said second control signal in such a manner that the magnitude of one of said signals ao and a1 changes to a certain value which, when combined vector-wise with said signal b1 produces a second composite signal output having a lagging phase angle of about 123* with respect to said signal ao.

Claim 12

A color subcarrier phase shift circuit comprising: a. first means which receives a first color subcarrier signal and operatingly shifts said first subcarrier signal by a specific phase angle theta to produce a second color subcarrier signal, said first means including a positive phase shift circuit comprising a capacitor and a resistor connected together in series, said first color subcarrier signal being applied across the series circuit of said capacitor and said resistor and said second color subcarrier signal being derived across said resistor; b. second means, which comprises first and second differential amplifier circuits for receiving said first and second color subcarrier signals at first and second input terminals thereof and for receiving a first control voltage at third and fourth input terminals thereof, for supplying said first and second color subcarrier signals at first and second output terminals thereof, while also producing third and fourth color subcarrier signals at third and fourth output terminals thereof, the phases of which are inverted with respect to said first and second color subcarrier signals, respectively; and c. third means, responsive to said first, second, third and fourth color subcarrier signals, for combining said second and third color subcarrier signals with respect to each other and for combining said fourth color subcarrier signal with one of said first and third color subcarrier signals and for producing fifth and sixth color subcarrier signals while receiving voltages for controlling the combining of said subcarrier signals; whereby each of said fifth and sixth color subcarrier signals has a specific phase relationship with respect to said first color subcarrier signal.

Claim 13

A color subcarrier phase shift circuit comprising: a. first means which receives a first color subcarrier signal and operatingly shifts said first subcarrier signal by a specific phase angle theta to produce a second color subcarrier signal, said first means including a positive phase shift circuit comprising a capacitor and a resistor connected together in series, said first color subcarrier signal being applied across the series circuit of said capacitor and said resistor and said second color subcarrier signal being derived across said resistor; b. second means, which comprises first and second differential amplifier circuits for receiving said first and second color subcarrier signals at first and second input terminals thereof and for receiving a first control voltage at third and fourth input terminals thereof, for supplying said first and second color subcarrier signals at first and second output terminals thereof, while also producing third and fourth color subcarrier signals at third and fourth output terminals thereof, the phases of which are inverted with respect to said first and second color subcarrier signals, respectively; and c. third means, responsive to said first, second, third and fourth color subcarrier signals, for combining said second and third color subcarrier signals with respect to each other and for combining said fourth color subcarrier signal with one of said first and third color subcarrier signals and for producing fifth and sixth color subcarrier signals while receiving voltages for controlling the combining of said subcarrier signals; whereby each of said fifth and sixth color subcarrier signals has a specific phase relationship with respect to said first color subcarrier signal.

Claim 14

A circuit according to claim 9, wherein said third means comprises a first signal composite circuit and a second signal composite circuit, each having first and second differential amplifiers, the first and second differential amplifiers of said first composite circuit being connected to the first and fourth output termiNals from said first and second differential amplifiers of said second means, and said first and second differential amplifiers of said second composite circuit being connected to the second and third output terminals of said first and second differential amplifiers of said second means, and wherein the output terminals of each of said first and second differential amplifiers of said first and second composite circuits are connected respectively in parallel across first and second load impedances to produce said fifth and sixth color subcarrier signals respectively.

Claim 15

A circuit according to claim 10 wherein each of said first and second differential amplifiers of said first and second composite circuits have first and second control terminals thereof connected in parallel and supplied with first and second control voltages from said fourth means.

Claim 16

A circuit according to claim 11, wherein said first and second differential amplifiers of said second means comprise transistor circuits, the emitters of which are respectively connected together through respective impedance elements to a first source of reference potential and the bases of which are connected to said first means and said first control voltage, respectively.

Claim 17

A circuit according to claim 12, wherein the first and second differential amplifiers of said first composite circuit have their emitters connected together and to the collectors of a first of the transistors of said first and second differential amplifiers of said second means, while the first and second differential amplifiers of said second composite circuit have their emitters connected together and to the collectors of a second transistor of said first and second differential amplifiers of said second means.

Claim 18

A circuit according to claim 13, wherein the bases of respective first and second transistors of each of said first and second differential amplifiers of said first and second composite circuits are connected together to form first and second control input terminals, for receiving said first and second control voltages from said fourth means, respectively.

Claim 19

A circuit according to claim 14, wherein the collector electrodes of the first and second transistors of each differential amplifier of each composite circuit are respectively connected together and wherein said first and second load impedances are connected between said connections of said first and second transistor collectors, said fifth and sixth output signals being supplied from the collectors of the respective second transistors of a differential amplifiers of said composite circuits and a second reference potential being supplied to the collectors of said first transistors of said differential amplifiers of said composite circuits.

Claim 20

A circuit according to claim 15, wherein each of said first and second transistors of said first means are connected in emitter-follower configuration.