Rca Inc.

Thomson Consumer Electronics Inc.

Thomson Licensing S.a.

Rca Licensing Corporation

Thomson Multimedia S.a.

Ronald E Fernsler

Alvin R Balaban

Steven A Steckler

Enrique Rodriguez-Cavazos

Walter Truskalo

Donald Henry Willis

John Barrett George

Kevin Michael Williams

Robert Joseph Gries

Nancy D Graves

William Benjamin Aaron

James A Wilber

David W Luz

Thomas D Yost

Kevin E Nortrup

Leroy W Nero

John Charles Peer

Peter Ronald Knight

James E Hicks

William V Fitzgerald

Michael Lee Henley

George C Waybright

Nancy Dawn Boettner

Sanjay R Vinekar

Ravadee Kliebphipat

An autotransformer steps up the output of a high voltage amplifier for applying a drive signal to the focus electrode of a CRT. A parabolic signal is obtained or generated at a deflection frequency such as the horizontal scanning frequency and is applied as an input to the amplifier. The amplifier output is coupled to a center tap of the autotransformer. One winding is serially coupled to the focus electrode and the other winding is AC coupled by a capacitor to ground, in parallel with the amplifier output. The transformer steps up the amplifier output voltage and can reduce the voltage rating required of transistors in the amplifier.

Dynamic focus amplifier output with step-up autotransformer

A dynamic focus voltage generator includes a source of a flyback input signal at a horizontal deflection frequency. A double integrator is responsive to the input signal for generating a parabolic periodic signal. An amplitude detector is responsive to the parabolic periodic signal for generating a control signal that is indicative of an amplitude of the parabolic periodic signal. A comparator is responsive to a signal at a reference level and to the control signal and coupled to the double integrator for regulating an amplitude of the parabolic periodic signal in a gain control negative feedback manner. A non-linear network is responsive to the parabolic periodic signal for producing a bathtub shaped output signal that is coupled to a focus electrode of a cathode ray tube.

Dynamic focus voltage amplitude controller

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. A raster correction transformer utilizes a raster centering inductor for a primary winding, and a horizontal-rate centering current is magnetically coupled into the vertical deflection coils to modulate the vertical deflection current.

Horizontal parallelogram correction combined with horizontal centering

An ultor voltage switching power supply for a cathode ray tube is energized by a low voltage switching power supply. A switching transistor of the ultor voltage switching power supply is disabled when a screen of the cathode ray tube is blanked. An anode capacitance of the cathode ray tube that develops the ultor voltage discharges via a bleeder resistor, when the switching transistor is disabled. As a result, a transient decrease occurs in the ultor voltage. The decreased ultor voltage tends to maintain the screen blanked.

High-voltage power supply disabling circuit for video display

A television apparatus set has the capability of selectively displaying picture information obtained from a broadcast television signal and a display monitor data signal. A zero voltage switching switch mode power supply generates a higher voltage B+ supply voltage for a horizontal deflection circuit output stage, when the deflection circuit output stage operates at a rate greater than or equal to approximately 32 KHz. A series-pass regulator power supply generates at a common supply terminal a lower voltage B+ supply voltage, when the deflection circuit output stage operates at a lower rate equal to approximately 16 KHz. During a start-up interval, the horizontal scanning output stage is supplied with the lower B+ supply voltage regardless of the scan frequency for reducing excessive stress in the horizontal output stage switching transistor to improve reliability.

Power Supply for a deflection circuit operating at multi-scan frequencies

A scan frequency detector is responsive to a horizontal synchronization signal to generate a data signal that is indicative of the horizontal scan frequency. A digital-to-analog (D/A) converter produces from the data signal an analog, output signal at a first level, when the horizontal frequency is within a first range of values, at a second level, when the horizontal frequency is within a second range of values and at a third level, when the horizontal frequency is within a third range of values. A first switch of a switched S-capacitor arrangement, is turned on, when the output signal is at the first level. The first switch and a second switch of the switched S-capacitor arrangement, are turned on, when the output signal is at the second level. Both the first and second switches are turned off, when the output signal is at the third level. The third and second levels are distinguished by a level detector that includes a zener diode.

Switch control signal generator

In a video display operable at multiple horizontal scanning frequencies, a synchronized high voltage generator is substantially undisturbed during synchronizing source selection or interruption. The generator comprises a controlled oscillator generating a drive signal. A source of pulses synchronizes the controlled oscillator and has a plurality of scanning frequencies. A high voltage generator is coupled to the drive signal and generates a display energizing supply. The scanning frequencies occur in two frequency bands, and when synchronized the oscillator generates the drive signal having a frequency only in a higher frequency band of the two frequency bands. In a further inventive arrangement a high voltage generator for a video display is operable at a plurality of horizontal scanning frequencies and is controlled such that the high voltage supply remains substantially constant during an interruption of horizontal scanning pulses from the source.

Synchronized high voltage generator

There is provided a circuit and method for generating a focus voltage having a predetermined waveform and magnitude for application to an electron beam focus means of a cathode ray tube having a display surface. A horizontal deflection current having a predetermined waveform and a frequency which is selectable over a predetermined range of frequencies is used to generate substantially horizontal scan lines on the display surface of the cathode ray tube by causing at least one electron beam to sweep across the display surface. The circuit has an input for receiving a signal having a current waveform representative of the waveform and frequency of the horizontal deflection current. In response to the received signal, the circuit produces a focus voltage output, the waveform and magnitude of which remain substantially constant over the range of selected frequencies of the horizontal deflection current.

Electron beam focus voltage circuit

A deflection waveform correction signal generator comprises a multiplying circuit for generating a pincushion correction signal. A horizontal frequency ramp is generated by a clipped retrace pulse. The ramp generator has an output coupled to an integrating circuit for generating a parabolic shaped signal. The ramp generator and ramp integrator are reset at a horizontal rate by reset pulses of differing duration. The different duration of reset pulses results in the parabolic signal having regions of non-parabolic shape. The parabolic shaped signal is coupled to an input of the multiplying circuit. A control circuit is coupled to the parabolic shaped signal for maintaining a peak amplitude thereof by controllable coupling to the ramp generator. A control loop is coupled to the integrator for controlling an integrator input bias current to generate the parabolic shaped signal at a predetermined time interval.

Shaped parabolic signal for deflection correction

Deflection correction signal generator

A video display having deflection correction comprising a cathode ray tube with a deflection coil mounted on the cathode ray tube for generation of a raster having horizontal line length variations which describe a generally sinusoidally shaped raster edge. A deflection amplifier is coupled to the deflection coil for generating a deflection current therein. A modulator is coupled to the deflection coil for generating a corrective current therein responsive to a corrective signal. A corrective signal generator for generating said corrective signal having a generally sinusoidal shape is coupled to the modulator for raster edge correction.

Raster edge correction waveform

A projection television receiver has a cathode ray tube with an electron gun for emitting an electron beam incident on a screen, an electromagnetic deflection yoke and an electromagnetic focusing coil. The focusing coil is included in a resonant circuit. The resonant circuit is energized by switching operation of a switching transistor in the vicinity of a retrace interval. Variations of the focusing coil current in the vicinity of the retrace interval provide dynamic focus.

Focus coil current generator for a cathode ray tube

In a horizontal deflection system, an nf.sub.H timing signal is generated synchronously with an f.sub.H horizontal synchronizing component in a video signal, where nf.sub.H is a higher frequency than f.sub.H. A first circuit is responsive to the nf.sub.H timing signal for generating an nf.sub.H scan synchronizing signal synchronously with the nfH timing signal. A horizontal deflection stage is operable at nf.sub.H and responsive to the nf.sub.H scan synchronizing signal. A second circuit is responsive to the same nf.sub.H timing signal for generating horizontal blanking pulses. The nf.sub.H timing signal can be generated by a first phase locked loop and a frequency divider. The first circuit responsive to the nf.sub.H timing signal can comprise a second phase locked loop. The second circuit responsive to the nfH timing signal can comprise a driver/inverter. The horizontal blanking pulses are combined with vertical blanking pulses to form a composite blanking signal.

Horizontal blanking

A first phase locked loop generates a first timing signal at a first horizontal synchronizing frequency corresponding to a horizontal synchronizing component in a video signal. A converter circuit derives from the first timing signal a second timing signal, having a second frequency at a multiple of the first frequency and subject to a variation in frequency at a rate corresponding to the first frequency. A second phase locked loop comprises a comparator, a low pass filter, a controllable oscillator and a horizontal output deflection stage receives the second timing signal, which can be asymmetric within the period of the first timing signal, and a feedback signal in accordance with the second frequency. The controllable oscillator generates a horizontal synchronizing signal at the second frequency. The second phase locked loop has a characteristic loop response, determined by the low pass filter, preventing the controllable oscillator from changing frequency as fast as the rate of variation of the second timing signal. This drives the error signal for the controllable oscillator toward an average value, resulting in a corrected, symmetric synchronizing signal at the second frequency. The horizontal output deflection stage is synchronized for horizontal scanning in accordance with the second frequency. No additional signal processing circuitry is needed to correct the symmetry of the first timing signal generated by the first phase locked loop or the symmetry of the second timing signal derived by the converter.

Synchronized scanning at horizontal frequency

An ultor voltage power supply includes first and second transformer windings that are coupled in series for producing corresponding first and second flyback pulse voltages. A first protection circuit disables the generation of each of the pulse voltages when the amplitude of the first pulse voltage becomes excessive. A second protection circuit disables the generation of each of the pulse voltages when the amplitude of the second pulse voltage becomes excessive.

Growing community of inventors

Indianapolis, IN, United States of America

Ronald E Fernsler