Abstract: A microprocessor generates an output signal in accordance with user controlled sharpness selection. The output signal is supplied to a video processor and to a scan velocity modulation circuit for concurrently varying in the same sense the amount of picture sharpness produced by the scan velocity modulation circuit and by the video processor.

Abstract: A picture in picture (PIP) video signal is applied to a display device via a non-linear processor that is enabled during display of a main picture component and disabled during display of an inset picture component responsive to a PIP identification signal. The non-linear processor is formed in an integrated circuit which includes a pin for connection to a capacitor that stores peak levels of the PIP video signal. The PIP identification signal is subjected to a voltage level translation for varying the pin voltage over a range of values, .DELTA.V, for facilitating ON/OFF operation of the non-linear processor and is applied to a selected plate of the capacitor for varying the pin voltage without substantial alternation of charge stored within the capacitor whereby only a single pin is required for both capacitor storage and on/off control of the non-linear processor and undesirable visual artifacts, such as "trailing contrast bars", are avoided.

Abstract: A bias source (R7,R8,C24) connected to a summing amplifier (Q1) produces a first DC bias at the amplifier input (emitter) and a second DC bias at the amplifier output (collector). A first circuit node (B) is AC coupled (22) to a luminance signal source (Y1, 18), DC coupled via a first resistor (R4) to the input of the summing amplifier and DC coupled via a first amplifier (28) to a luminance load (Y3,30). A second circuit node (A) is AC coupled (20) to a chrominance signal source (C1,18), DC coupled via a second resistor (R3) to the input (emitter, Q1) of the summing amplifier and DC coupled via a second amplifier (26) to a chrominance signal load (C3,30). A third amplifier (Q2) provides DC coupling of the output of the summing amplifier (Q1) to a composite video signal load (E,40).

Abstract: A composite video input signal is separated into luminance and chrominance components by a signal separation filter and the components are applied to a display processor having a video display device coupled thereto for providing displayed images. For enhancement of detail in dark and light areas of the displayed images, the luminance signal is coupled to the display processor via a non-linear luminance signal processor which provides additional amplification in the dark and light areas but tends also to degrade the signal to noise ratio in those areas. To avoid a loss of signal to noise ratio in the enhanced areas the receiver includes a by-pass circuit for by-passing high frequency components of the luminance signal around the non-linear luminance signal processor and a filter in the non-linear luminance signal processor for attenuating the high frequency components.

Abstract: The present invention concerns a high impedance signal source driving a relatively low input impedance mechanical resonating device such as a ceramic filter having an input impedance which varies with frequency. The high impedance source is further loaded by a resonant circuit tuned to the center frequency of the mechanical resonating device. The skirts of the resonant tuned circuit decrease in impedance on both sides of the center frequency of interest substantially compensating for the change of circuit gain with frequency due to the change of input impedance with frequency of the ceramic filter.

Abstract: A diode is connected at a first electrode thereof to a source of input signal to be switched via a capacitor and is connected at a second electrode thereof via an output circuit to an output terminal. A bias control circuit, coupled to the diode, provides a first operating mode in which the diode is forward biased for coupling the input signal to the output terminal via the output circuit and provides a second operating mode in which the first electrode of the diode is DC isolated so that the diode rectifies the AC component of the input signal and in so doing generates a reverse bias for self-biasing the diode to a non-conductive condition.

Abstract: A television receiver provides a noise-free set up signal by automatically selecting an unused baseband video input terminal, or an unused pair of SVIDEO input terminals. Selection of the unused terminals provides a D.C. level to the luminance path, and allows the horizontal oscillator to free-run. In addition to selecting an unused video input terminal, the subject apparatus automatically increases the brightness level a few steps to simulate a 7.5 IRE flat field (commonly known as set up). The above-listed steps may be performed manually by a service technician, for television receivers not incorporating apparatus for automatically performing the steps.

Abstract: A color television receiver includes a picture-in-picture processor and a variable filtering circuit for imparting a "slope type" filtering characteristic to the chrominance component of displayed signals when the main picture being displayed is from a tuner video source and for imparting a "hay-stack" type filtering characteristic to the chrominance component when the main picture picture being displayed is from an auxiliary video source thereby providing an effective reduction in the visibility of chrominance signal sideband amplitude errors when displaying picture-in-picture images from different types of sources.

Abstract: A so-called "one-chip" television IC includes a dual purpose input terminal for receiving a control signal representing an image property, such as a contrast, and also a signal having an amplitude within a predetermined range for enabling a test mode of operation. The control signal is generated by at least first and second control circuits. The first control circuit provides a first control signal set by a user. The second control circuit provides a second control signal in response to the image content of an image-representative signal produced by the integrated circuit, and may comprise a beam current limiter responsive to the beam current drawn by an image reproducing device or a circuit responsive directly to the image-representative signal. The first and second control signals are combined to produce a combined control signal which is applied to the dual purpose input terminal.

Abstract: A television system includes a one-chip television signal processing IC including luminance and chrominance signal processing sections and character signal input terminals intended to receive character signals corresponding to the colored characters to be displayed by an associated display device and a character brightness control terminal intended to receive an adjustable DC control signal for setting the brightness of the colored characters. A blanking signal for blanking the video image is coupled to one of the character signal input terminals instead of a character signal, and an IC supply voltage corresponding to a black image level is coupled to the character brightness control terminal instead of an adjustable DC brightness control signal. The blanking signal is used for blanking the video image behind a displayed character body and also for emphasizing displayed characters, e.g., by "edging" the character bodies.

Abstract: A control circuit comprises a first detector for detecting amplitude excursions of a signal related to luminance information beyond a white level threshold during each horizontal scan. This enables the circuit to be more sensitive by responding to excursions occurring during each horizontal scanning line. A first timer, responsive to the first detector, provides a first control signal related to a minimum duration of each amplitude excursion of the signal bey ond the threshold. A switch and second timer, responsive to the first control signal, provide a second control signal which falls at a first rate to reduce the signal; and, which rises at a second rate to permit the signal to increase after termination of the amplitude excursion, until the next minimum duration excursion. The time constant for the second rate is much greater than the time constant of the first rate.

Abstract: Switches are cascaded for improved off-state attenuation. The first switch of the cascade comprises an L-type attenuator with series branch including a resistor and a shunt branch including a Zener diode. A bias network coupled to the attenuator and to the second switch of the cascade connection controls the diode bias for operation at a specific forward conduction when the second switch is open and for operation at a specific reverse bias condition when the second switch is closed for causing the attenuator to provide the plural functions of (1) enhancing the switch off-state attenuation, (2) providing over-voltage and overcurrent protection for input transients of either polarity and (3) providing a predetermined output DC level when the second switch is on for establishing the DC bias of a subsequent circuit, such as an amplifier, the DC bias so supplied being in a tracking relationship with DC power supplied to the subsequent circuit.

Abstract: A color television receiver includes a comb filter having luminance and chrominance outputs coupled to respective inputs of a display processor. A signal source provides composite and non-composite color video signals for display. A switching circuit having a first operating mode for coupling the composite video signal to an input of the comb filter for enabling display thereof by said display processor. The switching circuit has a second operating mode for coupling the luminance component of the non-composite video signal to the input of the comb filter and for concurrently coupling the chrominance component of the non-composite video signal to the chrominance output of the comb filter for facilitating display of the non-composite video signal by said display processor.

Abstract: A video source is coupled to a display processor by a circuit path including a comb filter and a luminance signal delay line and including a comb filter amplitude correction circuit. Circuit means in the path prevents impedance variations of the correction circuit from causing reflections in the delay line thereby preventing image blur due to such reflections. In a preferred embodiment this feature is provided using existing receiver circuitry thereby providing the further technical and economic advantage of improved reliability and providing a cost reduction.

Abstract: A video display monitor operable at different horizontal deflection frequencies incorporates a circuit that produces an electron gun control grid potential that compensates for screen grid potential changes due to changes in operating frequency. A sawtooth signal is generated that has a peak to peak amplitude determined in response to the deflection frequency. The sawtooth signal is peak detected to produce a direct voltage, for the control grid, that varies in response to the horizontal deflection frequency.

Abstract: An auxiliary video input terminal (S-terminal) couples luminance and chrominance input signals to respective inputs of peaking circuits in the display processor of a receiver. The chrominance input signal is subjected to pre-distortion (de-peaking) to correct for sideband amplitude distortion in the chrominance peaking filter of the receiver thereby preventing color distortion in displayed images. The luminance signal is subjected to additional peaking at a frequency greater than the characteristic peaking frequency of the luminance peaking filter thereby enhancing the sharpness of wideband luminance input signals displayed by the receiver.

Abstract: An auxiliary video input terminal (S-terminal) couples luminance and chrominance input signals to respective inputs of peaking circuits in the display processor of a receiver. The chrominance input signal is subjected to pre-distortion (de-peaking) to correct for sideband amplitude distortion in the chrominance peaking filter of the receiver thereby preventing color distortion in displayed images. The luminance signal is subjected to additional peaking at a frequency greater than the characteristic peaking frequency of the luminance peaking filter thereby enhancing the sharpness of wideband luminance input signals displayed by the receiver.

Abstract: A temperature compensation network for an integrated circuit amplifier in a television receiver includes a thermistor mounted physically adjacent to, and electrically connected in parallel with the brightness control potentiometer, to the brightness control terminal of the integrated circuit. By mounting the thermistor in close proximity to the integrated circuit to be controlled, the thermistor is able to compensate for both self-heating of the integrated circuit and ambient temperature variations.

Abstract: An auxiliary video input terminal (S-terminal) couples luminance and chrominance input signals to respective inputs of peaking circuits in the display processor of a receiver. The chrominance input signal is subjected to pre-distortion (de-peaking) to correct for sideband amplitude distortion in the chrominance peaking filter of the receiver thereby preventing color distortion in displayed images. The luminance signal is subjected to additional peaking at a frequency greater than the characteristic peaking frequency of the luminance peaking filter thereby enhancing the sharpness of wideband luminance input signals displayed by the receiver.

Abstract: A television receiver having picture-in-picture capability and having multiple electronically selectable auxiliary baseband signal inputs provides automatic selection of the proper audio signal by use of bilevel digital switching circuitry.