Thomson Consumer Electronics Inc.

Rca Inc.

Other

Rca Licensing Corporation

Lawrence E Smith

Peter Ronald Knight

John Barrett George

James A Wilber

Walter Truskalo

Michael Lee Henley

Enrique Rodriguez-Cavazos

Kevin Michael Williams

James H Wharton

Joseph C Stephens

Marvin N Norman

Sammy S Henig

Steven C Wetta

Robert A Breidigan

Mark T Carnes

Michael E Boyer

An electron beam tends to slope downwardly as it is deflected horizontally to form a raster in a video display apparatus. The sloping of the beam can cause geometric errors in the raster, for example orthogonality and parallelogram errors. A raster correction circuit substantially offsets the downward slope of the electron beam by modulating a vertical deflection current with an induced horizontal-rate raster correction current, thereby substantially eliminating orthogonality and parallelogram errors in the raster. In respective embodiments of an inventive arrangement taught herein, the horizontal-rate raster correction current is induced in the vertical deflection coils by magnetically coupling a filament pulse waveform, a horizontal deflection voltage waveform, or a horizontal deflection current into the vertical deflection coils.

Vertical deflection circuit with raster correction

An electron beam tends to slope downwardly as it is deflected horizontally to form a raster in a video display apparatus. The sloping of the beam can cause geometric errors in the raster, for example, orthogonality and parallelogram errors. A raster correction circuit offsets orthogonality and parallelogram errors in a raster by modulating a horizontal deflection current at a vertical scanning rate. The raster correction current is phased in relation to a horizontal-rate deflection current such that scan lines in an upper-half portion of the raster are shifted to the right, and scan lines in a lower-half portion of the raster are shifted to the left.

Horizontal deflection circuit with raster correction

A source of an input supply voltage is coupled via a current limiting resistor to a load. A diode has a first terminal that is coupled to a junction terminal between the resistor and the load. A second terminal of the diode is coupled to an output of a regulated power supply where a regulated supply voltage is developed. The diode clamps a second output supply voltage developed at the first terminal of the diode to the regulated supply voltage. When the power in the load exceeds a predetermined value, the diode ceases conducting. In this way, the conductor that couples the second output supply voltage to the load need not meet the strict 15 watt node spacing requirements.

Power limiting regulator

A focus supply circuit, comprising: a power source for generating a high voltage for energizing a cathode ray tube, including a transformer having a high voltage winding with at least one intermediate output tap; and, a focus screen assembly, having a resistive chain with an input terminal coupled for receiving the high voltage, a focus output terminal for energizing a focus electrode of the cathode ray tube and at least one intermediate input tap between the input terminal and the focus output terminal, coupled to the at least one intermediate tap of the high voltage winding by an independent conduction path. An effective bias current for the cathode ray tube flows in the resistive chain. The voltages at the intermediate taps correspond to one another within a tolerance. The conductive path presents sufficiently low impedance to substantially inhibit variation of the high voltage due to variation of leakage current from the focus electrode.

Cathode ray tube focus supply

A screen grid voltage or a focus voltage for a cathode ray tube is controlled via a digital-to-analog converter. The voltage variation range of the screen grid or focus voltage that can be obtained for the entire variation range of an output signal of the digital-to-analog converter is not significantly larger than that required for the type of cathode ray tube that is utilized.

Bus controlled electrode voltage for a cathode ray tube

In a horizontal deflection circuit output stage, a retrace pulse voltage is developed in a primary winding of a flyback transformer and transformer-coupled to a secondary winding and rectified for developing a high voltage. A portion of the transformer-coupled rectified voltage is combined in a voltage divider with a second rectified voltage. The second rectified voltage is produced in a peak rectifier from the retrace pulse voltage in the primary winding in a manner that bypasses the secondary winding. A screen grid voltage is developed at a terminal of the voltage divider. A change in beam current loading produces variations in opposite sense in the combined rectified voltages in a manner to regulate the screen grid voltage.

Voltage regulator for CRT electrode supply

A first resonant retrace circuit is operable for generating a first voltage signal and a second resonant retrace circuit coupled to the first resonant retrace circuit is operable for generating a second voltage signal summed with the first voltage signal. An auxiliary winding of a flyback transformer in the first resonant retrace circuit generates a first feedback pulse signal representative of the first voltage signal. A regulator senses the summed first and second voltage signals and generates a second feedback pulse signal representative of the summed first and second voltage signals. The second resonant retrace means is responsive to the regulator. A resistive summing junction combines the first and second feedback pulse signals to generate a composite feedback pulse signal. A voltage level is generated indicative of the energy in the composite feedback pulse signal. An overvoltage protection circuit is responsive to the voltage level for disabling operation of at least one of the first and second resonant retrace circuits.

Overvoltage protection system for televisions

An apparatus for cutting an article into sheets includes an upper jaw pivotally mounted to a lower jaw. The lower jaw includes three coplanar cutting edges, and the upper jaw includes three cutting edges which cooperate with those of the lower jaw. Longitudinal cutting edges of the upper jaw are curved along their lengths, and the end element of the upper jaw is slanted with respect to the end element of the lower jaw. The apparatus may be attached to existing mounting points of a backhoe.

Apparatus for cutting an article into sheets

Retrace pulses are integrated by an R-C network to produce a ramp signal. The resistive member of the R-C network is bypassed by a diode to provide rapid retrace at the conclusion of the ramp portion of the integrated signal. A voltage divider at the output of the integrator adjusts the DC level of the ramp signal without affecting the constant of integration of the R-C network.

Centering circuit

A compensating coil for a scanning electron beam display, such as a color television tube, reduces undesirable deflection of the electron beams due to ambient magnetic fields, in particular the geomagnetic field. The coil has a winding disposed to encircle the tube neck, perpendicular to the Z axis. A degaussing coil is positioned on the tube envelope to provide for demagnetizing metal structures within the envelope. In order to provide more complete degaussing, the supply current to the compensating coil is interrupted during the degaussing operation. In order to prevent a charge from accumulating on the compensating coil, one terminal is coupled through a resistor to a source of reference potential.

Magnetic field compensation apparatus

An accessory track apparatus have a track disposed at a peripheral region of a top plate supporting a piece of equipment such as a personal computer. One or more accessory holders are inserted into the track by way of an octagonal anchor plate on the holders, which anchor plate allows insertion and removal of the holders at corners of the track. A space or cavity between the top support plate and track allows for 360.degree. routing of electrical wiring of up to several feet in length.

Accessory track to accommodate multiple accessories

A voltage at a control grid of a cathode ray tube is generated at a blanking level to provide beam current blanking when horizontal deflection loss occurs. The control grid voltage at the blanking level is developed in a capacitor prior to an instant in which the horizontal deflection loss occurs. When the capacitor voltage is applied to the control grid to provide the blanking level, the capacitor is discharged slowly. To maintain the capacitor charged, prior to such instant when horizontal deflection is lost, the capacitor voltage is not applied to the control grid as long as the horizontal deflection is normal, regardless of whether vertical deflection loss occurs. Either horizontal deflection loss or vertical deflection loss will disable a video driver stage that controls the cathode of the cathode ray tube for providing additional beam current blanking capability.

Projection TV deflection loss protection circuit

A parabolic voltage generating circuit includes an arrangement for generating a sawtooth vertical deflection current that flows in a vertical deflection winding, in a DC blocking capacitor and in a deflection current sampling resistor. An emitter electrode of a transistor is coupled between the deflection winding and the capacitor. A base electrode of the transistor is coupled between the capacitor and the resistance. A collector current of the transistor varies in a vertical rate parabolic manner and has a DC average value that is determined by a DC average value of a voltage that is developed in the capacitor. The collector current is applied to an East-West raster distortion correction circuit for modulating an amplitude of a horizontal deflection current.

Parabolic voltage generating circuit

An SCR switch of a switch mode power supply is coupled between an unregulated supply voltage and a filter capacitor. A regulator oscillator generates trigger pulses for controlling a switching operation of the SCR switch of the power supply to produce an output supply voltage that energizes a deflection circuit. The regulator oscillator produces trigger pulses that are applied to the SCR switch during both power-up and power-off operation. A resistor coupled between the unregulated supply voltage and the filter capacitor maintains the filter capacitor charged during power-off operation to prevent the trigger pulses from causing the latching operation in the SCR switch throughout the power-off operation. In this way, an audible parasitic vibration sound is not being generated by the power supply during the power-off operation.

Television apparatus power supply

A switch regulator includes a controllable SCR switch that is coupled in series with a filter inductor and a horizontal deflection generator, and the series combination is coupled across a source of unregulated direct voltage for providing a path for an increasing current flow in the inductor during a portion of a trace interval in which the switch is closed. Horizontal rate signals are coupled from the deflection generator to the switch via a first winding for controlling the opening of the switch. A catch diode is coupled to the filter inductor to form a path for a decreasing current flow in the first inductor during at least a portion of a retrace interval. The first winding is coupled in series with a second inductor to form an arrangement that is coupled between the unregulated voltage and the SCR switch. A current in the second inductor maintains the switch conductive during a portion of retrace that varies in accordance with a beam current for improving regulation of an ultor voltage.

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Indianapolis, IN, United States of America

Lawrence E Smith