Abstract: A fully automatic white balance control circuit which is sensitive to changes in the ambient or incident illumination as well as to changes in the object being viewed includes a main photo-sensor having a video output from which three primary color signals are derived, three external or incident light sensing elements having spectral characteristics the same as those of the main photo-sensor for the three primary colors, three capacitors for converting output currents from the three external light sensing elements to respective voltages, a voltage comparator for comparing a voltage across at least the one capacitor corresponding to green light with a reference voltage, and three sample-and-hold circuits for sampling and holding voltages from the three capacitors, respectively.

Abstract: A control apparatus for controlling a plurality of characteristics, such as hue, color, brightness, sound and the like, of a reproduced video picture includes a transmitter having a memory for storing data entries corresponding to the characteristics to be controlled, a central processing unit to change selected ones of the stored data entries and a plurality of switches for controlling the central processing unit to change selected ones of the stored data entries in response to actuation of selected ones of the switches, whereby the transmitter transmits the stored data entries, as changed; a receiver including a shift register in which the transmitted control data entries are serially received and converted into parallel control data entries, a D-A converter for producing a plurality of analog control voltages in response to the parallel control data entries from the shift register; and a plurality of voltage-controlled circuits for controlling the plurality of characteristics in response to the plurality o

Abstract: A filter circuit, preferably a low-pass filter, whose cut-off frequency is easily controlled and which can be manufactured as an integrated circuit. First and second transistors are connected in differential amplifier configuration, and a current source is connected to the common connection of the emitter electrodes thereof. The base electrode of the first transistor is connected to an input terminal. A reactance element is connected between the collector electrode of the second transistor and a source of reference potential, such as ground. A third transistor has its emitter electrode connected to the base electrode of the second transistor and its base electrode connected to the collector electrode of the second transistor. An output terminal is connected to the emitter electrode of the third transistor.

Abstract: In apparatus for processing an information signal, such as, the chrominance component of a reproduced color video signal, time base errors composed of phase and frequency errors are eliminated by detecting phase and frequency errors, respectively, of the chrominance component, frequency converting the chrominance component with a frequency converting signal which is generated, at least in part, by means of a variable frequency oscillator, controlling such oscillator by an automatic phase control circuit (APC) in response to detected phase errors within a predetermined or lock-in range of the APC so as to eliminate such phase errors from the frequency converted chrominance component, and further controlling the variable frequency oscillator in response to only those detected frequency errors which correspond to time base errors beyond the lock-in range of the APC for returning to within such range.

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.

Abstract: Apparatus for eliminating time base errors from a carrier-modulated information signal, such as a color video signal which is reproduced from a record medium. A circuit including a variable oscillator generates a carrier signal of controllable frequency and phase. An automatic frequency control circuit detects the time base frequency error in the carrier-modulated information signal and produces a frequency error signal proportional to the detected frequency error. An automatic phase control circuit detects a time base phase error in the carrier-modulated information signal and produces a phase error signal proportional to the detected phase error.

Abstract: In an apparatus for processing reproduced color video signals composed of a frequency-modulated luminance component and a frequency-converted chrominance component having its carrier frequency substantially below a standard frequency therefor; there are provided a drop-out compensating circuit responsive to a drop-out in the luminance component for inserting, in the interval of such drop-out, an earlier occurring portion of the luminance component, a frequency-converter receiving the chrominance component and a frequency-reconverting signal for restoring the carrier frequency to the standard frequency therefor, an automatic frequency control circuit (AFC) responsive to horizontal synchronizing signals separated from the luminance component after the drop-out compensation thereof so as to regulate the frequency-reconverting signal in the sense for removing time base errors from the reproduced color video signals, and a circuit which is responsive to a drop-out in the luminance component for maintaining the fre

Abstract: A phase detector comprising a first differential amplifier for receiving a first input signal and having an output circuit which produces an output that is a direct function of the first input signal. An actuable second differential amplifier receives a second input signal and includes an output circuit for producing an output signal which is proportional to the phase difference between the first and second input signals. The second differential amplifier is coupled to the first differential amplifier output circuit so as to be actuated by the output produced by the output circuit and to thereby produce an output signal representing the phase difference between the second input signal and the output supplied by the first differential amplifier output circuit. The output produced by the first differential amplifier output circuit is supplied as a differential amplifier current to the second differential amplifier.

Abstract: A DC level control circuit wherein the DC level of an input signal is compared to a reference level and a DC bias potential is varied in accordance with said comparison, the varied bias potential being fed back to correspondingly vary the DC level input signal.