Abstract: In a video signal processing system including an image displaying kinescope and a kinescope driver stage, a version of signals processed by the driver stage and video output signals from the driver stage are combined to produce a resultant high frequency signal respresentative of high frequency components deficient in the video output signal. The resultant signal is applied to an input of the driver stage to compensate for the high frequency deficiency otherwise manifested by the video output signal.

Abstract: Excessive peak beam currents conducted by a kinescope in a color television receiver are limited by apparatus which compares the combined instantaneous magnitudes of plural color signals with a fixed threshold and, if exceeding the threshold, the combined signal is detected. The detected signal is used to limit the magnitudes of the color signals, thereby limiting excessive kinescope beam currents otherwise developed in response to the color signals. The apparatus is used in the receiver together with a more conventional automatic kinescope beam current limiter of the type which operates in conjunction with a kinescope resupply current source.

Abstract: A color television receiver with luminance and chrominance signal channels includes an automatic kinescope beam current limiter, an automatic white level drive control network, and an automatic black level bias control network. A switching network is timed to operate such that a control signal developed by the beam current limiter is coupled to the luminance channel during normal picture intervals, but is decoupled from the luminance channel during both white level drive control intervals and black level bias control intervals. The beam limiter control signal is continuously coupled to the chrominance channel, independent of the operation of the switching network, to permit chrominance output bias offset errors produced by beam limiter action to be sensed and compensated for by the automatic bias control network.

Abstract: A brightness control circuit in a video signal processing system includes an amplifier and an adjustable brightness control coupled to the amplifier input, which also receives keying pulses via a resistor-capacitor input circuit. Output pulses from the amplifier exhibit a brightness determinative amplitude related to the setting of the brightness control. To maintain a substantially constant waveshape for the output pulses as the brightness control is adjusted, a shaping capacitor is coupled between the input and output of the amplifier.

Abstract: Brightness control apparatus for a video signal processing system wherein the video signal is pre-conditioned to establish a prescribed reference level during image blanking intervals. The prescribed reference level is afterwards further modified by adding a black-going pulse component to the video signal during the blanking intervals. The magnitude of the added pulse component is adjusted in accordance with the setting of an adjustable brightness control to control the brightness of images displayed by an image display device included in the system. Controlled video signals are AC coupled to an intensity control electrode of the display device by a DC restoration circuit which responds to the magnitude of the added blanking interval pulse component, for establishing the DC bias of intensity control electrode and thereby image brightness.

Abstract: A kinescope driver stage in a television receiver includes an input pre-driver transistor and an output driver transistor arranged in a cascode amplifier configuration. To enhance the high frequency response of the driver stage, a capacitor is coupled from the signal input of the driver transistor to a point of reference potential.

Abstract: In a video signal processing system such as a video monitor including an automatic kinescope bias (AKB) control system, the time required for the AKB system to initially achieve correct kinescope biasing is reduced with respect to a given interval of time beginning when the video processing system is initially energized. This is accomplished by reducing a storage time constant of the AKB system during the given interval, and by pre-charging a storage element of the AKB system during the given interval.

Abstract: In a television receiver, the bias of the G2 screen grid of an image displaying kinescope is adjusted to produce a black level condition for the kinescope. Prior to adjusting the screen grid bias, the normal bias voltage of both the cathode and G1 grid electrodes of the kinescope are modified to produce a predetermined cathode-to-G1 grid voltage.

Abstract: A kinescope driver amplifier includes a signal gain determining feedback network coupled from the output to the input of the amplifier. A normally non-conductive switching network coupled to the feedback network is rendered conductive in response to large amplitude video signals for modifying the impedance of the feedback network so as to reduce the signal gain of the amplifier during the occurence of such large video signals.

Abstract: A signal voltage from a signal processing path is coupled via an interfacing terminal to an input port of a filter, the output port of which is connected to the base input of a current source transistor to supply thereto a signal voltage which exhibits the filter transfer function. The collector output of the current source transistor is also coupled to the interfacing terminal and conducts a current exhibiting the filter transfer function to the signal path via the interfacing terminal. The base input of the current source transistor is driven with filter output sigals via a low output impedance voltage source (e.g., an emitter follower stage). The impedance presented to the base of the transistor is primarily determined by the low output impedance of the voltage source.

Abstract: A projection-type television system includes apparatus for providing frequency selective compression of video signals. Low frequency video signal components representative of white image information above a threshold level are subjected to relatively greater compression compared to high frequency video signal components representative of white image information.

Abstract: In a television receiver, an automatic kinescope beam current limiter circuit includes a current path between a beam current sense point and an interating capacitor across which a control voltage is developed. A threshold conduction device causes the current path to exhibit different impedance characteristics and associated response times so that the limiter circuit has the ability to respond to average beam current values, as well as to above average r.m.s. beam current values such as may be associated with peak beam current conditions.

Abstract: An electrical signal processing network includes a high order, two port, three terminal filter, and means coupled to the filter for synthesizing, at a single terminal, an impedance exhibiting the transfer function of the filter. The synthesized impedance can be coupled to a single point in a signal path for filtering signals in accordance with the transfer function of the filter.

Abstract: In a television receiver, apparatus for non-linearly processing a vertical detail signal includes first and second cascaded amplifiers which exhibit linear and limiting regions for processing a vertical detail signal. A first keyed sample and hold circuit provides detail signal amplitude samples to the first amplifier. A second keyed sample and hold circuit provides amplitude samples of sampled detail signals from the output of the first amplifier, to the second amplifier. The sampling circuits operate at different times such that the second sampling circuit is operative in a sampling state at times when the first sampling network is inoperative and exhibits a holding state. Output detail signals from the first and second amplifiers are combined with a linear version of the vertical detail signal to produce a combined, output vertical detail signal manifesting signal coring, amplification, and paring (attenuation) over selected amplitude ranges.

Abstract: A color television receiver with luminance and chrominance signal channels includes an automatic kinescope beam current limiter, an automatic white level drive control network, and an automatic black level bias control network. A switching network is timed to operate such that a control signal developed by the beam current limiter is coupled to the luminance and chrominance channels during normal picture intervals, decoupled from at least the luminance channel during white level drive control intervals, and coupled to at least the chrominance channel during black level bias control intervals.

Abstract: In a TV receiver responsive to either conventional television video signals or an auxiliary video signal representative of alphanumeric text or graphic information, to prevent undesired "blooming" of the display due to high kinescope beam currents when the alphanumeric text or graphics are displayed on the screen of a kinescope, means are provided for reducing at least one amplitude characteristic of the auxiliary video signal, such as its peak-to-peak signal level (contrast) so as to reduce the kinescope beam current whenever the alphanumeric text or graphics are displayed.

Abstract: To prevent undesired bending of vertical bar type information displayed on the screen of a kinescope due to kinescope beam current variations, modifying circuits are provided for reducing the beam current threshold level of an automatic beam current limiter stage to a lower threshold level whenever vertical bar type information is displayed.

Abstract: In a wideband video signal processing system, video output signals from a video driver amplifier are passively AC coupled to an intensity control electrode of an image display device. A keyed feedback DC restoration circuit is connected to the intensity control electrode via a high impedance resistor network comprising the feedback path of the restoration circuit. Image brightness control is accomplished via the restoration circuit without varying the operating point of the driver amplifier.

Abstract: A kinescope driver stage includes an input amplifier transistor arranged in a cascode amplifier configuration with an output amplifier transistor. The low impedance emitter electrode of the input transistor is coupled to a reference potential via an impedance network. Degenerative feedback is provided from the impedance network to input circuits of the input amplifier.

Abstract: A high voltage generator in a television receiver responds to horizontal deflection rate signals from a horizontal oscillator which normally responds to a horizontal sync signal derived from the television signal. A sync validity detector provides a control signal indicative of the validity of the horizontal sync signal to an electronic tuning system in order to identify active channels, and to the deflection system to inhibit the response of the deflection system to false sync signals otherwise capable of causing the oscillator to operate a lower frequency likely to cause the high voltage generator to develop an excessively high voltage.