Abstract: A VCR or laserdisc player includes circuitry for detecting a code provided by VCR tapes, tape cassettes, or laser videodiscs, which indicates that the material recorded on the videotape or videodisc has been recorded in a compressed fashion to enable proper playback on a 16.times.9 television receiver. In response to detection of this code, the VCR or laserdisc player applies a DC signal to the chrominance output terminal of its S-Video connector. Circuitry in the television receiver detects the DC signal on the chrominance terminal of its S-Video input connector, and controls a wide-screen processor to expand the image by displaying it over the entire width of the 16.times.9 display screen.

Abstract: A differential current source (50) provides first and second complementary output currents (I1, I2) responsive to a video input signal (S1) which are coupled via respective load networks (52,54) to a common supply terminal (22) and develop first and second complementary video output signals (V1,V2). A first output circuit (56) applies the first output signal to a first output terminal (16) via a voltage follower transistor (Q6) and applies the second output signal to the first output terminal via a current source transistor (Q8). A second output terminal (18) is similarly driven by a second voltage follower transistor (Q5) and a second current source transistor (Q7), all transistors being of the same conductivity type. A tri-state control circuit (Q1,Q2) coupled to the differential current source enables the differential current source in a first operating mode to produce the first and second complementary currents whereby push pull output signals are produced at the output terminals.

Abstract: A television receiver embodying the invention includes a plurality of luminance signal sources, each capacitively coupled to an input of a luminance signal selection switch and each capacitor being coupled to a respective clamp circuit with each clamp circuit having a reference voltage input coupled to a common reference voltage source. A sync separator is provided having a first input coupled to receive the output of luminance signal selection switch and a second input coupled to a source of reference potential derived from said reference voltage source. Advantageously, the overall number of clamp circuits is minimized by merging the sync separator circuit with the input signal selection clamping circuit.

Abstract: A video signal to be processed is applied to a non-linear processor having an adjustable gain responsive to a control signal over at least one portion of the amplitude range of the video input signal. A sampling circuit, responsive to the video signal, generates video samples related to the video signal. A control circuit, responsive to the video samples, generates the control signal in accordance with the number of samples in at least a given amplitude range thereby controlling the percentage of samples of a given range in displayed images. Plural control and sampling circuits may be included provide control for white stretch processing, black stretch processing and video mid-point processing for enhancing contrast through out the entire video signal range.

Abstract: A clamp system for use in a television receiver having tuner and auxiliary video sources, comprises an IF AGC and video detector circuit having an AGC reference voltage input and an auxiliary video input signal clamp circuit having a reference voltage input. The detector circuit and the clamp circuit are each formed on a common integrated circuit along with a video switch for selecting video signals provided by said detector and clamp circuits. The integrated circuit further includes a reference voltage source and a bias generator for deriving the AGC reference voltage and the auxiliary input signal clamp voltage from the common source.

Abstract: A video input signal to be displayed is applied to an offset clamp circuit which effects a DC offset of blanking and active video portions of each video line. The DC offset or shift is of an amount and in a polarity sense to place the black level of the active portion of an NTSC color standard signal at a level corresponding to blanking level of the NTSC color standard. Advantageously, subsequent clamping at the shifted level enables contrast control without altering the black level of displayed images.

Abstract: A luminance signal filter for use in a multi-source television receiver, includes a tunable filter responsive to a bandwidth control input signal for determining the bandwidth of luminance signals applied to said filter and a variable delay circuit inversely responsive to said bandwidth control input signal for providing a substantially uniform overall delay for said luminance signal filter.

Abstract: In a TV system which includes an autopix feedback loop limiting the range over which the contrast can be controlled, there is included means for generating a non-linear contrast control voltage as a function of customer control settings in order to extend the range over which the customer can control the contrast.

Abstract: A fixed filter determines a lower portion of the amplitude characteristic of a chrominance signal sideband correction filter. A variable filter determines the upper portion of the amplitude characteristic. A control signal tunes the variable filter for providing a symmetrical response for video signals having balanced color sidebands and tunes the variable filter for providing an asymmetrical response for video signals having unbalanced sidebands.

Abstract: Video signal processing circuit including a source of composite luminance signals having image-representative components separated by regularly recurring synchronizing signal components; keyed clamp and signal clipping circuit coupled to the luminance signal source and responsive to back porch keying pulses for clamping a back porch interval of the composite luminance signal to a predetermined direct voltage level, the keyed clamp and signal clipping circuit further including a voltage sensitive signal clipping circuit responsive to the direct voltage level and to the clamped composite luminance signals for removing synchronizing signal components from the composite components; chrominance signal processing circuit for demodulating a color subcarrier signal to produce a plurality of color difference signals; a source of keying pulses recurring during the synchronizing signal interval; and a plurality of keyed clamp circuits each responsive to the synchronizing signal interval keying pulses and individually re

Abstract: Two transistors are operated individually as emitter follower buffer amplifiers for R-Y and B-Y input signals and are operated together as an inverting summing matrix for deriving a G-Y output signal from the R-Y and B-Y input signals. All three output signals are "buffered" (i.e., provided by low impedance sources) and are subject to substantially equal delays. Advantageously, the circuit implementation requires only two transistors and three resistors to provide output signals which are (1) buffered, (2) matrixed and (3) delay compensated and which features improved reliability (due to reduced "parts count") and an economic implementation of the buffering, delay compensation and matrixing functions.

Abstract: A television receiver includes a "one-chip" television signal processing IC which has a terminal for receiving a composite video signal including both image and synchronization pulse components. A composite video signal which has been non-linearly processed by a so-called "black-stretch" circuit is coupled to the composite video signal input terminal of the "one-chip" IC. In order that a sync separator of the "one-chip" IC can reliably separate the synchronization pulses from the composite video signal after it has been non-linearly processed, a sync correction circuit, including an auxiliary sync separator, is used to modify the synchronization pulses of the composite video signal after it is non-linearly processed and before it is coupled to the "one-chip" television IC.

Abstract: In a color television system having picture-in-picture (PIP) capability, apparatus is provided for automatically modifying the operation of a beam current limiting (BCL) section while the small picture is being displayed to prevent the visibility of the small picture from being adversely affected. In the preferred embodiment, a contrast BCL control signal is decoupled from the contrast section, and a substitute control signal, at least approximating the user responsive contrast control signal, is substituted for it in response to a switching signal which causes the small picture to be inserted within the big picture. However, the BCL section continues to be responsive to the beam current during the time interval in which the small picture is displayed so that the BCL contrast signal accurately represents the contents of the entire image.

Abstract: A television system includes a picture tube beam current limiting arrangement which operates to reduce image contrast without affecting image brightness when the beam current exceeds a first threshold. However, if the user brightness control setting exceed the nominal (midrange) brightness control level, the image brightness is reduced when the beam current exceeds a second threshold which may be equal to or greater than the first. The image brightness is reduced only until the image brightness is within a small margin of the nominal image brightness level. Any further beam current limiting, for example to account for abnormal operating conditions of the television system are accomplished by further brightness reductions.

Abstract: A non-linear (e.g., "white stretch") processor and a brightness control processor are coupled in cascade between an input for receiving a video input signal to be processed and an output for providing a processed video output signal. A control signal for controlling the transfer characteristics of the non-linear processor is provided by an amplifier having a first input coupled to receive an average picture level (APL) indicating signal derived from the processed video output signal and having a second input coupled to receive a reference level signal supplied thereto. A brightness control signal is applied to a control input of the brightness control processor for controlling the brightness level of the processed video output signal.

Abstract: A signal processor responsive to a video input signal provides a first video output signal linearly related to the input signal and a second video output signal non-linearly related to the video input signal. A first combining circuit combines the first and second video output signals in predetermined proportions to provide a third video output signal having both linear and non-linear components. A second combining means combines the second and third video output signals in proportions determined by an average picture level (APL) representative control signal to provide a processed video output signal having enhanced contrast for all values of the average picture level of displayed images.

Abstract: Apparatus for separating sync and video includes a luminance signal coupling capacitor, a keyed clamp circuit coupled to a source of back porch keying pulses for clamping a back porch interval of the composite luminance signal to a reference direct voltage level, and signal clipping means comprising at least one voltage follower amplifier device and a threshold biasing semiconductor device of the same conductivity type as the voltage follower amplifier connected to the output electrode of the voltage follower, such that the biasing device maintains the voltage follower in cutoff conduction condition for signals of one polarity with respect to the reference voltage while producing a predetermined direct voltage output across a load resistance and for allowing coupling of signal components of opposite polarity with respect to the direct voltage level to a utilization device.

Abstract: The present invention concerns a non-linear transfer function generator, e.g., for implementating "white stretch" of a luminance signal. Specifically, first and second emitter-follower amplifiers have their inputs coupled in parallel and their outputs coupled in series via first resistor of a voltage divider. A second resistor of the voltage divider is coupled to a point of reference potential. A bias source is coupled to the second amplifier, e.g., via the second resistor of the voltage divider, so that the dynamic response of the second amplifier to an input signal is limited with respect to the first amplifier. The output signal of the first amplifier is linear and an output signal developed at the output of the second amplifier is non-linear. The linear and non-linear output signals are combined by a current steering network in response to a control signal representative of a characteristic of a processed version of the luminance signal.

Abstract: A television system is disclosed including sections for limiting peak white drive to a display device (e.g., of the direct view of projection type) while maintaining relatively high subjective image contrast and brightness. Specifically, the system includes an automatic contrast control section for controlling the amplitude of the luminance signal in response to the peak value of a luminance-representative image component signal preceded by a "white-stretch" control section for emphasizing mid-range luminance components relative to high-range luminance components as a function of the average value of the luminance-representative image component. In this way, spot blooming and display driver saturation can be minimized while providing subjectively sharp, bright pictures.

Abstract: A level setting apparatus for adjusting the brightness of a television receiver is modified by the setting of an amplitude control apparatus for adjusting the contrast such that the maximum brightness level of the image on a CRT is modified in direct relationship to the adjusted level of contrast.