Sony Corporation

Seiji Sanada

Katsuo Isono

Toshiyuki Yamauchi

Kazuo Yamagiwa

Hideshi Tamaru

In a color television system having a video tape recorder and a color television receiver which includes an automatic control circuit for automatically controlling color level and hue with a reference signal contained in a predetermined horizontal scanning line section of a video signal, and which is so designed that a broadcasting signal and a reproduced signal of the video tape recorder are selectively received by the color television receiver, the automatic control circuit rendered inoperative in response to a change-over operation by which the color television system is changed over to apply the reproduced signal of the video tape recorder to the color television receiver.

Color television receiver and VTR system

Hue and color saturation are controlled in response to a received VIR signal, the latter having a chrominance reference portion and a luminance reference portion. The level of a preselected one or more demodulated color signals which are produced by the color demodulator in color video signal receiving apparatus is detected during the time that the VIR signal is received. The level-detected demodulated color signal is used to produce a control signal for controlling the hue or color saturation. A storage circuit, such as a capacitor, is provided to store the control signal throughout the duration which separates successive VIR signals. A VIR detector is provided for detecting the presence of a VIR signal in the received video signal; and when the absence of a VIR signal from the received video signal is detected, the control signal storage circuit is preset to a predetermined value. By so presetting the storage circuit, the time required for successful VIR-controlled color correction is minimized when the video signal receiving apparatus is switched from, for example, one broadcast channel which does not include a VIR signal to another broadcast channel which does include a VIR signal. In a preferred embodiment, both hue and color saturation are controlled in response to a VIR signal. The level of a selected color difference signal (R-Y), produced during the chrominance reference portion of the VIR signal, is used to control hue; and the level of a simulated color drive signal (B), also produced during the chrominance reference portion of the VIR signal, is used to control color saturation.

VIR-Controlled color correction for color video signal receiving

In a color video display device, such as a television receiver or a monitor associated with a color video tape recording and reproducing apparatus, and which is responsive to a composite color video signal including a luminance component and a chrominance component containing a chrominance signal, a burst signal and a chrominance reference portion of a vertical interval reference (VIR) signal; a hue-correction circuit is provided for dynamic correction of chrominance phase errors. The hue correction circuit includes a phase comparator that provides an output in response to the phase difference between the burst signal and the chrominance reference portion of the VIR signal, an oscillator for providing a continuous wave at the frequency of the burst signal, a controlled amplifier acting on the luminance component and having its gain controlled by the output of the phase comparator to provide a correction signal, and a phase modulator for adjusting the phase difference between the chrominance signal and the continuous wave signal in response to the correction signal. The phase comparator can include first and second sample-and-hold circuits for sampling the chrominance phase during the burst signal and during the chrominance reference portion of the VIR signal, respectively. The hue correction circuit can also include a clamp for clamping the output of the controlled amplifier to a reference level during the burst signal.

Hue correction circuit

Color control apparatus for use in color video receiving apparatus of the type capable of receiving a color video signal which includes a VIR signal, the latter having at least a chrominance reference signal therein. A chrominance channel is provided for processing the chrominance component included in the color video signal. An extracting circuit connected to the chrominance channel separates burst and chrominance reference signals from the received color video signal. A predetermined parameter in the separated burst signal is detected, and a corresponding parameter in the chrominance reference signal is detected. A common amplifier is responsive to the detected parameters for producing an amplified control signal which, in turn, is supplied to an adjustable circuit so as to adjust a color characteristic of the processed chrominance component in accordance with the amplified control signal. The detected parameters may be the level of the respective burst and chrominance reference signals, which levels are detected by comparison with a reference level. The detected burst signal level thus is used in an automatic chrominance control circuit, and the detected chrominance reference signal level is used in a color saturation control circuit, both of these control circuits being connected with the common amplifier for controlling the color saturation level of a processed chrominance component. Also, the detected parameter may be the respective phases of the burst and chrominance reference signals with respect to a local oscillating signal used for demodulating the chrominance component. In that event, the detected burst signal phase and chrominance reference signal phase are used in automatic phase control and hue control circuits, respectively, both of these control circuits being connected to the common amplifier. In a preferred embodiment, the color control apparatus includes an ACC and a saturation control circuit connected to one common amplifier for controlling color saturation, and an APC circuit and a hue control circuit connected to another common amplifier for controlling the hue characteristic of the ultimately demodulated color signals.

Common circuitry VIR control apparatus for color television receiver

A hue correction circuit for use in video display apparatus which is responsive to a composite color video signal including luminance, chrominance, burst and VIR signals. A controllable local oscillator circuit generates a reference oscillating signal of controllable phase for use in demodulating the chrominance signal. A first phase control circuit is responsive to the burst signal for deriving a first phase control signal as a function of the phase error between the burst signal and the reference oscillating signal, this first phase control signal being applied to the local oscillator circuit to vary the phase thereof for minimizing the phase error. A gain controlled amplifier is connected to receive the luminance signal and has a controllable gain for deriving a second phase control signal as a function of the luminance signal, this second phase control signal being applied to the local oscillator circuit to vary the phase thereof. The gain of the gain controlled amplifier is varied as a function of the phase error between the chrominance reference component included in the VIR signal and the reference oscillating signal. In one embodiment, the local oscillator circuit comprises a voltage-controlled oscillator which receives the first phase control signal as the control voltage therefor, the output of this voltage-controlled oscillator being coupled to a controllable phase shifter which receives the second phase control signal. In another embodiment, the local oscillator circuit is a voltage-controlled oscillator whose phase is controlled by the output of a matrix circuit, the latter receiving both the first and second phase control signals. In this embodiment, a differentiated version of the luminance signal is amplified by the gain controlled amplifier to produce the second phase control signal.

VIR-controlled hue correction circuit

A color correction circuit responsive to a VIR signal that includes a clamping circuit to clamp a color demodulated signal to a predetermined voltage level during the chrominance reference portion of the VIR signal. A sample-and-hold circuit samples the luminance reference portion of the VIR signal immediately succeeding the clamped portion and holds the sampled value, and a comparator compares the sampled signal with the predetermined clamping voltage to generate an error-correction voltage that can be applied to a gain-control amplifier in the chrominance channel to correct saturation and to a phase-control circuit to adjust the hue by shifting the phase of the locally generated subcarrier.

Color correction circuit for a color television receiver

Color television receiving apparatus for receiving and demodulating a composite color television signal including hrozintal synchronizing signals, color burst signals, and luminance and chrominance components. This composite color television signal is of the type which additionally may or may not include a VIR signal which, typically, is broadcasted in a predetermined line interval during the vertical retrace period of the composite color video signal. The apparatus includes the demodulator for demodulating the chrominance component, which has been separated from the composite video signal, into its color signal components. A signal generator generates a signal, such as a gate signal, during the predetermined line interval in which the VIR signal is expected. Control circuitry is energized by this generated signal to respond to selected components produced by the demodulator during the line interval in which the VIR signal is provided for producing signals which are used to control the color signal components demodulated by the demodulator, such as to control the hue and saturation of such demodulated components. Manually operable adjusting circuitry is coupled to the control circuitry for selectively varying the control signals in accordance with an operator's particular preference for hue and/or saturation characteristics of the reproduced color video picture. In one embodiment, switching circuitry is provided to selectively energize the control circuitry either with the aforementioned generated gate signal or, in the event that the transmitted video signal is not provided with a VIR signal, with an alternative periodic gating signal, such as a signal derived from the horizontal sync signal.

Color television control circuit for use with a VIR signal

Color television receiving apparatus is provided for receiving a composite television signal which includes horizontal synchronizing signals, color burst signals and luminance and chrominance components. The composite color television signal is of the type which additionally may include a VIR signal which is provided in a predetermined line interval during the vertical retrace interval. The receiving apparatus comprises signal processing circuitry for processing the received composite color television signal so as to produce a video picture therefrom. A sampling signal generator generates sampling signals during the predetermined line intervals in which the VIR signal is provided. A VIR detector is coupled to the signal processing circuitry and is responsive to the sampling signals to detect if the VIR signal is included in the received composite color television signal. At least one component produced by the signal processing circuitry is sampled by the sampling signals to produce sampled control signals. A manually adjustable generator produces manually adjustable control signals; and switching circuitry coupled to the sampling circuitry and to the manually adjustable generator is controlled by the VIR detector to selectively supply either the sampled control signals or the manually adjustable control signals to control circuitry which, in turn, controls the signal processing circuitry so as to control predetermined characteristics of the reproduced video picture. These controlled characteristics may be the luminance levels or color characteristics, such as hue and saturation, or both luminance levels and color characteristics. An improved type of sampling circuit which can be used with this color television receiving apparatus also is disclosed.

VIR control apparatus for color television receiver

A color television receiver having a color picture tube with a screen for displaying a color picture in response to the reception of a composite color television signal which includes a phase reference signal, such as, the chrominance reference portion of a VIR signal, is provided with a circuit for generating variable reference color signals and for causing the color picture tube to display, on at least a portion of its screen, areas of respective colors corresponding to the variable reference color signals, a demodulating circuit for demodulating the phase reference signal and the chrominance component of the color television signal for obtaining demodulated color signals from such chrominance component, a hue correction circuit responsive to the demodulated phase reference signal for correcting errors in the hue of the color picture displayed on the screen in correspondence to the demodulated color signals due to phase distortions in the chrominance component of the received color television signal, and a manually actuable hue adjuster for simultaneously and correspondingly varying the relation of the demodulated color signals to each other and the relation of the variable reference color signals to each other so that the hue of the areas of colors displayed on said screen will correspond to the hue of the color picture displayed on the screen. The color television receiver is further provided with a circuit for generating fixed standard color signals having a relation to each other representing a predetermined standard hue, and for causing the color picture tube to display, on a second portion of its screen adjacent the first mentioned portion of the screen, areas of primary colors corresponding to the standard color signals so that the relation of the hue of the displayed color picture to the standard hue can be readily determined by visual comparison of the areas of colors on the first portion of the screen with the respective areas of primary colors on the adjacent second portion of the screen.

Growing community of inventors

Yokosuka, Japan

Seiji Sanada