Abstract: As described above, according to the present invention, there is provided a color CRT display having a one-beam electron gun for reproducing colors by sequentially switching respective chrominance signals, R, G, and B, supplied to the one-beam electron gun. The color CRT display is characterized in that a color image displayed on a CRT screen is picked up by a CCD image pickup device and the image pickup signal is stored in an image pickup signal memory, the image pickup signal is compared with an original video signal stored in a video signal memory in terms of components of chromaticity using an arithmetic operator, and the frequency and phase of the image pickup signal of a VCO, which are required for determining the switching timing of chrominance signals in a multiplexer, are adjusted so that the difference between the image pickup signal and the original video signal in terms of components of chromaticity is minimized.

Abstract: A phase-tracking loop circuit which can be used, for example, as an FM detector or as a frequency-tracking control circuit to control the index signal of a beam-index cathode ray tube (CRT), includes an adder receiving an input signal of fluctuating frequency, a tracking filter coupled to the output of the adder and whose passband center frequency is shiftable, in response to a control voltage, to follow changes in the frequency of the input signal, an attenuator feeding an attenuated version of the output from the tracking filter back to the adder for combining in the latter with the input, and a phase comparator comparing the phase of the output of the adder with the output of the tracking filter to provide a corresponding control voltage to the tracking filter. If used as an FM detector, the control voltage can also constitute a demodulated signal.

Abstract: In a beam index color television receiver having the screen of its color cathode ray tube provided with a repetitive pattern of a plurality of groups of different primary color phosphor elements arranged side-by-side across the image area of the screen to be scanned by a single electron beam as the latter is selectively modulated by respective color signals, index and mode set signals are provided in response to scanning by the beam of respective locations on the screen which are interspersed across the latter with distances therebetween which are non-integrally different from the pitch of the groups of color phosphor elements, and with adjacent locations corresponding to the mode set signal being spaced apart by an integral multiple of such pitch.

Abstract: A color television receiver includes an automatic phase control circuit (which will be hereinafter referred to simply as an APC circuit) with a voltage controlled oscillator for controlling the phase of a reference carrier supplied to a color demodulator so that the phase and frequency of the reference carrier are locked to those of a color burst signal. In addition to the APC circuit, an auxiliary frequency control loop drives the frequency of the voltage controlled oscillator until its frequency falls within the lock-in range of the APC loop. The auxiliary frequency control loop includes a counter circuit for counting cycles of the output signal of the voltage controlled oscillator during a reference time interval and a decoding circuit for decoding the output of the counter circuit to produce an auxiliary control signal for frequency control of the voltage controlled oscillator.

Abstract: In an automatic phase control circuit having a predetermined lock-in range wherein the oscillating signal produced by the adjustable oscillator of the automatic phase control circuit is used in combination with an input signal to derive a signal whose phase is compared to a reference signal, the phase difference between the derived signal and the reference signal being used as a phase control signal for the oscillator so as to minimize this phase difference and thus lock the phase of the derived signal to that of the reference signal, a method of adjusting the oscillator in the event that the phase relation between the oscillating signal and the input signal is outside the lock-in range. During recurrent intervals, which vary with time base errors in the input signal, the number of cycles of the oscillating signal is counted.

Abstract: A clamping circuit for color television signals includes a demodulator for demodulating the chrominance component of the color television signals to produce first and second color difference signals, and first and second adders for adding adjustable first and second control signals to the first and second color difference signals so as to produce modified first and second color difference signals. A matrix circuit is responsive to the outputs from the first and second adders to produce a third color difference signal.