Abstract: 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.

Abstract: A dynamic focus voltage generating circuit comprises a source of DC voltage coupled to a focus electrode of a cathode ray tube. A source of varying voltage is coupled to the focus electrode through a capacitance formed by a pair of coaxial conductors. The outer conductor of said coaxial pair is coupled to said source of varying voltage, and the inner conductor of said coaxial pair is coupled to said source of DC voltage.

Abstract: 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.

Abstract: An active pull up arrangement coupled to a high voltage source generates an operating voltage. An amplifier for a dynamic focus modulating signal is energized by the operating voltage and has a plurality of transistors, for example low voltage transistors, coupled as Darlington pairs in a differential configuration. One of the low voltage transistors is coupled in series between a resistor in the pull up arrangement and a return supply, for example ground, in a push pull configuration. A fault condition in the push pull configuration can destroy the resistor and cause an open circuit condition. A switch, for example a diode or a Zener diode, is coupled between the one transistor of the amplifier and the supply return. The switch prevents reverse breakdown of the transistors in the event of the fault condition, until the resistor is destroyed. The resistor may be a fusible resistor.

Abstract: 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.

Abstract: A convergence correction circuit, for a cathode ray tube projecting images having keystone, differential sine and differential left edge curl distortions, comprises generators for horizontal rate sine, horizontal rate sawtooth and horizontal rate pulse waveforms. A summer combines the horizontal rate waveforms into a horizontal rate composite waveform. A multiplier and an amplifier generate as an output signal a product of the horizontal rate composite waveform and a vertical rate sawtooth waveform. A convergence correction coil is coupled for receiving the output signal and generating a dynamic magnetic field correcting the keystone, differential sine and differential left edge curl distortions.

Abstract: 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.

Abstract: A dynamic focus amplifier, comprising: a first circuit responsive to a vertical rate sawtooth waveform for generating at the vertical rate a modulating waveform having a desired component of a given shape during trace intervals and an undesired time compressed version of the given shape during retrace intervals; a second circuit responsive to the sawtooth waveform for generating a pulse waveform at the vertical rate, substantially corresponding in width and phase to a vertical retrace blanking waveform; and, a differential amplifier stage, formed by Darlington pairs, for combining the modulating waveform and the pulse waveform to remove the undesired time compressed version of the given shape from the modulating waveform. The second circuit may comprise a capacitor which is charged in a first direction by the sawtooth waveform during vertical trace and charged in an opposite direction during vertical retrace.

Abstract: 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.

Abstract: A video display having raster correction comprises a cathode ray tube with a deflection coil mounted thereon for raster generation. A deflection amplifier is coupled to the deflection coil for generating a deflection current therein. A corrective waveform modulator is coupled to the deflection amplifier for generating a first corrective current in the deflection coil. An auxiliary coil is mounted on the cathode ray tube for raster correction. An auxiliary coil drive amplifier is coupled to the auxiliary coil for generating a second corrective current in the auxiliary coil. A first corrective signal is coupled to the waveform modulator for generating raster correction at a first raster edge and a second corrective signal is coupled to said auxiliary coil drive amplifier for generating raster correction at an edge opposite the first raster edge.

Abstract: A current transformer has a primary side winding coupled to a source of horizontal rate sawtooth yoke current and a secondary side in which a horizontal rate AC signal is developed. A rectifier has at least one capacitor, the rectifier receiving the horizontal rate AC signal and energizing a DC voltage across the at least one capacitor. A modulator for the DC voltage generates a first deflection rate waveform. A capacitor coupled to the modulator and to the secondary side of the transformer generates a second deflection rate waveform. The first and second deflection rate waveforms are combined to define a vertical dynamic focus voltage signal.

Abstract: 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.

Abstract: An analog multiplier generates an output signal that is coupled to a convergence winding of a projection television. The analog multiplier multiplies a horizontal rate sawtooth signal with a vertical rate parabola signal. The multiplier DC operating point is adjusted, by developing a DC voltage in a hold capacitor of a sample and hold arrangement during each vertical blanking interval. To prevent a change in the capacitor voltage during vertical trace, a vertical rate sawtooth signal is coupled to the hold capacitor via a second capacitor.

Abstract: An analog multiplier is used for generating an output signal that is coupled to a convergence winding of a projection television. The analog multiplier multiplies a horizontal rate sawtooth signal with a vertical rate parabola signal. To prevent temperature related drift, tolerances and component aging from affecting the output signal, the multiplier is calibrated during each vertical blanking interval.

Abstract: A temperature compensated vertical rate trapezoidal waveform is produced using piecewise linearization technique. The waveform is applied to a focus electrode of a cathode ray tube to provide a dynamic focus voltage.

Abstract: A source of switched supply voltage is applied to a potential divider and coupled to an output terminal via a capacitor. An output tap of the potential divider is coupled to the output terminal via the conduction path of a grounded base transistor. In operation the transistor (1) operates in an inverted mode for initially charging the capacitor, (2) operates in either a normal or an inverted mode for regulating a grid bias voltage at said output terminal for grid current flow of either direction relative to the output terminal and (3) operates in an isolation mode upon removal of the switched supply voltage whereby the capacitor applies a negative grid cut-off bias to the output terminal, said transistor in said isolation mode preventing discharge of the capacitor thereby providing a grid cut-off bias at said output terminal having an extended cut-off time constant due to the lack of any discharge path for the capacitor other than leakage.

Abstract: A circuit for protecting a cathode ray tube screen from damage by an electron beam includes a semiconductor switch device having an input coupled to a signal related to a deflection signal for the electron beam. The switch device is coupled to a voltage supply and the circuit further includes a charge storage device coupled to the switch device and further coupled to a control grid of the cathode ray tube. The charge storage device is charged through the switch device by the voltage supply when the deflection signal is present at a control input of the switch device. The switch device decouples the supply voltage from the charge storage device when the deflection signal is not present and places a negative blanking voltage developed on the charge storage device across the control grid when the deflection signal is not present to cut-off beam current in the cathode ray tube.

Abstract: A source of kine supply voltage is coupled to a video amplifier that drives a cathode of a cathode ray tube of a projection television receiver via a self biasing diode. When, due to, for example, a fault condition, the kine supply voltage is lost, the self biasing diode decouples the cathode of the cathode ray tube from a supply return terminal of an ultor supply voltage to form a high impedance, low capacitance at the cathode of the cathode ray tube. A beam current develops a self biasing voltage at the cathode of the cathode ray tube that substantially reduces the beam current to provide protection against a damage to a screen of the cathode ray tube.

Abstract: A television receiver includes a kinescope and a current sensing transistor for conveying amplified video signals to the kinescope, and for providing at a sensing output terminal an output signal related to the magnitude of kinescope current conducted during given sensing intervals. A clamping circuit clamps the sensing output terminal during normal image intervals, and unclamps the sensing output terminal during the sensing intervals. The clamping circuit facilitates interfacing the sensing transistor with utilization circuits which process the sensed output signal, and assists to maintain a proper operating condition for the sensing transistor.

Abstract: In a television receiver including a kinescope, a kinescope driver stage includes a video amplifier with an associated feedback path. A first emitter follower transistor couples amplified video signals from the amplifier output to the kinescope. A second emitter follower transistor, included in the feedback path for maintaining the continuity thereof, couples amplified video signals to the kinescope when a normally nonconductive diode coupled between the outputs of the emitter follower transistors is rendered conductive in the presence of large video signal amplitude transitions sufficient to render the first follower transistor nonconductive.