Eastman-kodak Company

Gte Products Corporation

Gte Sylvania Incorporated

John D Lovely

George H Kam

Douglas W Constable

Christopher M Downs

A method and apparatus for detecting the presence of a synchronization signal in at least one of a red, green and blue video input signal is disclosed, that permits signal processing to occur on the red, green and blue video input signals after the synchronization signal has been removed therefrom, while providing a reconstituted synchronization signal that is combined with the red, green and blue video signals after the completion of the signal processing.

Method and apparatus for providing sync on R-G-B video signals

Video reproduction apparatus records a field of a high resolution time-division-multiplex (TDM) video signal on first and second adjacent tracks on a magnetic tape. A head switch signal is included within the TDM video signal recorded on the tape in order to minimize skew errors which may occur in mid-field when switching between video signals sequentially played back from the first and second tracks. Each track has recorded thereon a plurality of horizontal lines of color video signals in a time-divisional-multiplex format including a compressed horizontal sync signal and compressed video component signals arranged in time sequential order. The compressed horizontal sync signal is deleted in a designated horizontal line signal at the end of the upper half of the field recorded on the first track such that the deleted horizontal sync signal constitutes a head switch signal. During playback, a head switch detecting circuit detects the deleted compressed horizontal sync signal in the designated line of the upper half field signal to effect a switch during the horizontal sync interval between the signals played back from the first and second tracks.

Head switching in high resolution video reproduction apparatus

Video reproduction apparatus records a field of a high resolution time-division-multiplex (TDM) video signal on first and second adjacent tracks on a magnetic tape. A head switch signal is included within the TDM video signal recorded on the tape in order to minimize skew errors which may occur in mid-field when switching between videosignals sequentially played back from the first and second tracks. Each track has recorded thereon a plurality of horizontal lines of color video signals in a time-divisional-multiplex format including a compressed horizontal sync service signal and compressed video component signals arranged in time sequential order. A head switch signal is inserted in the compressed horizontal sync service signal of a designated horizontal line signal at the end of the upper half of the field recorded on the first track. During playback, a head switch detecting circuit detects the head switch signal in the designated line of the upper half field signal to effect a switch during the horizontal sync service interval between the signals played back from the first and second tracks.

A circuit for selecting one of a number of video signals to be processed by a television receiver. The circuit comprises diode means having inputs suitable for coupling to alternate sources of video signals. A bias source applies a bias voltage to the diode means and control means applies various control voltages to the diode means. The relationship of the control voltages to the bias voltage determines which of the alternate sources of video signals are coupled to the output of the diode means.

Video switch circuit

A circuit for generating an accurately-timed noise-free signal for gating the chrominance burst portion of the composite video signal. The horizontal sync pulses are differentiated and clamped to the horizontal blanking pulses. The output pulses are then applied to a gating diode that is conductive only when those pulses have an amplitude above a predetermined bias level. The resultant pulses are coupled to the input of a burst gate so that the gate is open only for a period of time substantially coterminous with the burst period. The burst gate is thereby rendered immune to noise signals occurring during the active line period and the accuracy of the gating signal is independent of the television receiver's horizontal time base.

Burst gating signal generating circuit

A protection circuit for television receiver picture tubes and related components which includes a diode which is forward biased during normal operation to provide coupling of the tube control grid to ground or reference potential and which is reverse biased during operation at excessively large beam currents, the reverse biasing of the diode causing the beam current to flow through a large grid-cathode resistor thereby effectively limiting electron beam current.

Television receiver picture tube protection circuit

A circuit utilizing a single clamp, and therefore requiring only a single bias supply, to DC clamp the inputs of the three chrominance amplifiers is shown. The clamp employs a switch that is connected to the bias supply and coupled by separate diodes to the inputs of the chrominance amplifiers. The switch and diodes are conductive only during the horizontal retrace period. As a result, during the retrace period, the amplifier inputs are clamped to a DC value determined by the bias supply; during the trace, or information-bearing period the inputs are isolated from the supply, as well as from each other.

Clamp circuit for RGB output stages

Disclosed herein are a circuit and a method for providing an appropriately-timed signal to the input of a chrominance burst gate. Horizontal synchronizing pulses are differentiated and clipped so that positive-going, exponentially decaying pulses are developed substantially coincidentally with the chrominance burst signal. The resultant pulses are then applied to one terminal of a switch. Horizontal flyback pulses are phase-delayed so that their peak amplitude occurs during the burst period. The phase-delayed pulses are applied to another terminal of the switch so that resultant pulses are shorted to ground except during a predetermined portion of the horizontal flyback period. As a result, a burst gating signal having a pulse width effectively equal to and coincident with the burst signal period is generated and applied to the input of the burst gate.

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Batavia, NY, United States of America

John D Lovely