Gte Sylvania Incorporated

Eastman-kodak Company

Robert C Wheeler

Kenneth J Burdick

William K Hickok

Wilfred L Hand

Gopal Krishna Srivastava

Paul G Wolfe

Douglas W Constable

Robert P Logan

Robert P Collette

A camera includes a photographic film having a given film speed which decreases when the film is exposed to light which varies from a given illumination level. A camera shutter is controlled by a timing circuit adapted to produce an exposure which is adjusted to compensate for the decreased film speed.

Exposure control apparatus with compensation for film reciprocity failure

A video processing system for a television receiver is shown. The video processing system includes a gain controlled stage through which a video signal is coupled. The gain of the stage is controlled to provide contrast control of the video signal. The video signal is also applied to an aperture correction circuit which develops an aperture correction signal including pre-shoot and over-shoot transient responses. The aperture correction signal is also coupled through the gain controlled stage so that it is amplified or attenuated by the same amount as the video signal. The output of the gain controlled stage is coupled to an output stage. A portion of the video signal from the output stage is compared to a reference voltage in a black level control circuit. The control signal from the black level control circuit is applied to the output stage to control the black level of the video signal. The disclosed video processing system is further adapted for fabrication in integrated circuit form.

Video processing system providing gain control, aperture control, and

A DC controlled amplifier is used to control the chrominance gain, and hence the color saturation, of a television receiver. The voltage on the wiper of a Color Control variable resistor and the output of an Automatic Color Level (ACL) detector are combined in a summing network to provide a DC voltage to the controlled amplifier. The ACL detector develops an output voltage that tends to maintain the peak-to-peak chrominance signal, and therefore the color saturation, at or below a threshold level. A control tracking circuit varies the threshold level in accordance with the voltage on the wiper of the color control variable resistor, thereby maintaining the dynamic range of the Automatic Color Level Control System relatively independent of the setting of the Color Control.

Automatic color level control system with threshold tracking

A video processing system for a television receiver is shown. The video processing system includes a gain controlled stage through which a video signal is coupled. The gain of the stage is controlled to provide contrast control of the video signal. The gain of the gain controlled stage is also automatically controlled in response to a beam current feedback to provide automatic contrast or white level control. In addition, the automatic control circuit provides beam circuit limiting by reducing the gain of the gain controlled stage to minimum in response to beam currents in excess of a threshold. An aperture correction signal is also coupled through the gain controlled stage so that it is amplified or attenuated by the same amount as the video signal. The output of the gain controlled stage is coupled to an output stage where the black level of the video signal is controlled by a black level control circuit. The disclosed video processing system is further adapted for fabrication in integrated circuit form.

Contrast control circuitry for a video processing system

A video processing system for a television receiver is shown. The video processing system includes a gain controlled stage through which a video signal is coupled. The gain of the stage is controlled to provide contrast control of the video signal. The video signal is also applied to an aperture correction circuit which develops an aperture correction signal including pre-shoot and over-shoot transient responses. The aperture correction signal is also coupled through the gain controlled stage so that it is amplified or attenuated by the same amount as the video signal. The output of the gain controlled stage is coupled to an output stage where the black level of the video signal is controlled by a black level control circuit. The disclosed video processing system is further adapted for fabrication in integrated circuit form.

Aperture correction circuitry for a video correction system

A video processing system for a television receiver is shown. The video processing system includes a gain controlled stage through which a video signal is coupled. The gain of the stage is controlled to provide contrast control of the video signal. The video signal is also applied to an aperture correction circuit which develops an aperture correction signal including a pre-shoot transient responses. The aperture correction signal is also coupled through the gain controlled stage so that it is amplified or attenuated by the same amount as the video signal. An automatic peaking control circuit receives the pre-shoot and over-shoot signals to generate an automatic control signal to control the gain of the aperture correction circuit. A tracking control circuit causes the automatic peaking control circuit to accurately track the setting of an adjustable control which controls the gain of the aperture correction circuit. The output of the gain controlled stage is coupled to an output stage where the black level of the video signal is controlled by a black level control circuit. The disclosed video processing system is further adapted for fabrication in integrated circuit form.

Automatic peaking control circuitry for a video processing system

A fleshtone and tint correction detector DC coupled to at least two of the first, second, and third demodulator stages of a color television receiver provides a control signal in response to a shift in differential potential output from the demodulator stages to effect a shift in phase angle of reference signals applied in the demodulators whereby fleshtone and other color errors are reduced with a minimum deleterious effect on other colors.

Modulated fleshtone and tint correction circuitry

A protection circuit for a television receiver which disables the television receiver by disabling the horizontal deflection circuit in response to fault conditions is shown. The protection circuit detects excessive current drain by a low voltage supply, excessive current drain by a high voltage supply, and excessive high voltage. In response to any one of these fault conditions, the horizontal deflection circuit is disabled.

Television receiver protection circuit

A signal receiver having a source of video signals includes an aperture correction system wherein an electron device coupled to the video signal source provides first and second oppositely-phased output signals which are applied to a circuit means to be differentiated and delayed respectively and applied to a summing terminal with desired preshoot and overshoot characteristics. Moreover, these characteristics are selectable by an adjustable impedance coupled to the circuit means providing the differentiated and delayed signals.

Adjustable aperture correction system

A cathode ray tube raster in a television receiver is blanked for selected channels chosen to receive audio information by a bias circuit coupled to a video signal source connected to a cathode ray tube wherein the bias circuit provides a given bias potential to the cathode ray tube when a modulated picture carrier signal is detected and a different bias potential blanking the raster of the cathode ray tube when an unmodulated picture carrier signal is detected.

Television receiver raster blanking system

A circuit for automatically setting the black level in a television receiver includes a comparator circuit coupled to a source of video signals, an adjustable DC potential, and a disabling potential and providing a control signal representative of a video information signal and vertical blanking signal in excess of a threshold level with a detector and limiter providing a DC potential derived from the control signal for setting the black level of a signal available at the video signal source.

Automatic black level setting circuit

A secondary control circuit including contrast control, brightness control, and a peaking circuit means are all disposed on a printed circuit board and coupled into the video circuit of a television receiver by one pair of connectors.

Contrast, brightness and peaking control circuit

Raster and particularly top and bottom pincushion distortion in a cathode ray tube system is corrected by applying a drive signal from the vertical output system of a television receiver to the vertical deflection winding of a yoke to effect activation of switching elements whereby correction signals of the proper phase and amplitude and derived from the horizontal scan system are applied to the vertical deflection winding such that a vertical deflection potential at a frequency fv is modulated by a horizontal deflection potential at a frequency fh and of the correct phase and magnitude.

Growing community of inventors

Elba, NY, United States of America

Robert C Wheeler