Abstract: A method for generating display correction waveforms for a CRT display comprises the steps of selecting one of a plurality of trace portions for forming part of a correction waveform, the trace portions having different average values. Completing each of the correction waveform by combining each selected trace portion with a respective retrace portion such that all completed correction waveforms have a predetermined average value. The correction waveforms may have vertical and/or horizontal rates.

Abstract: For control and correction of deflection parameters especially of convergence, a grid pattern is displayed on the picture screen of a television device. For control of the convergence parameters and the evaluation of the correction values the crossing points of the grid pattern are marked by a cursor. The cursor is formed by at least one irregularity in the grid pattern being, regular otherwise. The irregularity may consist in an omission within the grid pattern like an interruption within one horizontal or vertical grid line. An image signal generator for the grid pattern with position cursor includes a raster generator, a grid generator, a cursor generator, and means for combining a grid signal from the grid generator and a cursor signal from the cursor generator so as to inhibit the grid signal corresponding to locations on the grid pattern where the position cursor is visible by an absence of display of portions of the grid pattern.

Abstract: A memory and a switchable digital filter supply different numbers of digital distortion correction values. The supplied distortion correction values are converted to an analog distortion correction signal. A passive, analog low pass filter for the analog distortion correction signal generates an analog deflection signal. The low pass filter is optimized only for those of the analog deflection signals having a given sample rate. A controller varies the different numbers of the supplied distortion correction values to maintain the given sample rate of the analog deflection signal for different horizontal scanning rates. The controller selectively implements respective operating modes for different horizontal scanning frequencies in which no interpolated distortion correction values are supplied or different numbers of interpolated distortion correction values are supplied.

Abstract: In a video display, correction data for a digital convergence arrangement are stored in a first non-volatile memory. During power turn on procedure, the correction data are read out of and stored in a volatile memory. During each deflection cycle, the data stored in the volatile memory are successively read out and applied to an auxiliary convergence winding. When a parity error is detected in the read out data, the data stored in a second non-volatile memory are automatically read out and transferred to the volatile memory and to the first non-volatile memory. The second non-volatile memory contains a duplicate of the correction data stored in the first non-volatile memory, during factory set up. The data in the second non-volatile memory are maintained parity error free. Thereby the parity error containing data stored in the first non-volatile memory are substituted with the data that are free of parity error, provided by the second, non-volatile memory.

Abstract: A horizontal deflection winding centering circuit includes a Darlington transistor and a diode. The Darlington transistor and diode form a non-linear network that is coupled in series with an inductor. The series arrangement of inductor and non-linear network is coupled in parallel with a horizontal deflection winding. The base voltage of the Darlington transistor is produced by a voltage divider coupled in a current path of the inductor current.

Abstract: An apparatus for convergence correction in a TV receiver with a CRT display comprises a display screen with photo sensors positioned adjacent to screen edges. A cathode ray tube generates a raster for illuminating the display screen and the photo sensors. A signal generator generates a video signal having a first part for convergence alignment and a second part having sufficient video signal amplitude to cause an average level of beam current loading corresponding to an average level that can occur during broadcast video reception. The video signal being coupled to the cathode ray tube for illuminating the display screen and sensors. The video signal facilitating convergence alignment with the average level of beam current loading to ensure that convergence alignment is maintained during broadcast video reception.

Abstract: A projection display apparatus comprises a display device forming an image for projection to illuminate a display screen. A current source generates a current. A current sink is adjacent to the display screen and is coupled to the current source for receiving the current. A detector is coupled to the current source and the current sink for receiving the current and detecting a presence of the received current. Wherein a first condition, absent illumination by the projected image on the current sink, the current from the source divides and is coupled to the detector in accordance with a first ratio, the detector assuming a first state indicative of the absence of illumination, and in a second condition in accordance with an intensity of illumination by the projected image on the current sink, the current from the current source is received by the current sink in accordance with a second ratio and the detector, absent the received current, assumes a second state indicative of illumination on the current sink.

Abstract: A method for generating display correction waveforms for a CRT display comprises the steps of selecting one of a plurality of trace portions for forming part of a correction waveform, the trace portions having different average values. Completing each of the correction waveform by combining each selected trace portion with a respective retrace portion such that all completed correction waveforms have a predetermined average value.

Abstract: A resistive voltage divider is responsive to a parabolic voltage developed in an S-shaping capacitor of a deflection circuit operating at a selected deflection frequency. The voltage divider includes a controllable resistive network for automatically selecting an attenuation factor of the voltage divider in accordance with the selected deflection frequency. An amplifier responsive to the attenuated parabolic voltage generates at an output terminal of the amplifier a periodic output voltage that is capacitively coupled to a focus electrode to produce a dynamic focus voltage. In a first embodiment, the controllable resistive network includes a photoresistor that provides automatic gain control. In an alternative, second embodiment, the voltage divider is switched.

Abstract: In order to accurately measure a low current bias in an automatic kine bias (AKB) circuit during several video lines that immediately follow vertical retrace, dynamic focus is interrupted by deactivating a dynamic focus voltage amplifier. The amplifier draws its power from a horizontal flyback transformer. In order to avoid a horizontal transient which may occur when the dynamic focus voltage amplifier is reactivated after being deactivated during a vertical blanking interval, the dynamic focus amplifier draws a current during vertical blanking which approximates the average current drawn during vertical scan.

Abstract: A projection display comprises a display device forming an image for projection onto a display screen. A photo sensor is adjacent to the display screen and generates a first signal responsive to a level of the projected image illumination incident on the photo sensor. A detector is coupled to receive the first signal and generates an output signal indicative of detecting the first signal. A source of a predetermined detection threshold value is coupled to the detector for determining a threshold at which the detection of the first signal occurs. Wherein the first signal exceeds the predetermined detection threshold value, the detector detects and generates the output signal indicative of signal detection, and generates a second signal for coupling to the source to change the predetermined detection threshold value.

Abstract: A switchable digital filter interpolates distortion correction values. The distortion correction values together with interpolated distortion correction values are supplied as an output. Proper operation of the digital filter is disturbed by transient signals occurring during horizontal retrace. The digital output is converted to an analog convergence correction signal. The digital to analog converter has an operating frequency and generates a transient signal during horizontal retrace as the operating frequency increases due to an increased horizontal scanning rate. A low pass filter receives the analog convergence correction signal and generates an analog deflection signal. An auxiliary deflection coil is driven by the analog deflection signal. The digital filter is switched off during the horizontal retrace. The digital filter is thus protected from disturbance by the transient signal and the digital to analog converter is protected from exceeding a maximum operating frequency.

Abstract: A video imaging apparatus includes a cathode-ray tube including a focus electrode. A source of a first parabolic signal at a frequency related to a deflection frequency, selected from a plurality of frequencies, has an amplitude determined in accordance with the selected frequency. A control circuit has an input coupled to the source of the first parabolic signal for generating an output signal. The output signal is for maintaining the amplitude of the first parabolic signal for the plurality of deflection frequencies. An amplifier, that is responsive to the output signal, is coupled to the focus electrode for amplifying the parabolic signal to generate a dynamic focus voltage at the focus electrode.

Abstract: A video imaging apparatus includes a source of a periodic dynamic focus voltage blanking signal. A dynamic focus voltage amplifier includes a switch responsive to the dynamic focus voltage blanking signal for applying a dynamic focus voltage to a focus electrode, when the switch is at a first state, and for disabling the application of the dynamic focus voltage, when the switch is at a second state to provide for automatic kine bias measurement. A second switch responsive to the focus voltage blanking signal is coupled to the amplifier for applying a current to a stage of the amplifier, when the dynamic focus voltage is disabled. The applied current adjusts the focus voltage, to a level closer to that established immediately after the dynamic focus voltage is enabled for reducing a transient condition.

Abstract: A direct current focus voltage applied to a focus electrode of a cathode ray tube that produces a blue image is set to slightly defocus the blue image for increasing the blue beam spot size. The increase in the blue beam spot reduces the saturation and allows brighter blue and increased blue video drive range. A passive network is coupled between an ultor electrode and the focus electrode to provide tracking of focus voltage-to-ultor voltage ratio. The tracking prevents voltage fluctuation of the ultor voltage produced by video loading from disturbing uniform defocussing in the entire blue image.

Abstract: A video display with data bus control has a standby and an operate condition. The video display comprises a microprocessor having a bi-directional data bus and is selectably operable in one of the operate and standby modes. A power supply is controllably coupled to the microprocessor for supplying power in one of the operate and the standby modes. An integrated circuit is coupled to the power supply and has bi-directional data bus control capability. A coupling device is responsive to the power supply and couples the bi-directional data bus to the integrated circuit in response to the operate mode and isolates the bi-directional data bus in response to the standby mode.

Abstract: A kinescope video driver includes a series connection of a main cascode transistor coupled to a cathode of a cathode ray tube and a video signal amplifying transistor. A second cascode transistor is coupled between the main cascode transistor and the video signal amplifying transistor. The second transistor is coupled to the video signal amplifying transistor through a short wire conductor and to the main cascode transistor through a long wire conductor.

Abstract: A power sensor circuit for use in a convergence system which comprises a convergence circuit for generating a convergence correction signal. The power sensor circuit receives at least one supply voltage and generates an output signal having a magnitude selected in accordance with whether the at least one supply voltage is above a first threshold. The output signal is coupled to the convergence circuit, which enables or disables the convergence correction signal in response to the magnitude of the output signal.

Abstract: A display system includes a kinescope. A horizontal scan detector is coupled to a source of a horizontal scan current signal and detects a loss of horizontal scanning. In addition, a vertical scan detector is coupled to a source of a vertical scan current signal including a feedback path and detects a loss of vertical scanning. A vertical feedback detector is also coupled to the vertical scan current signal source, and detects a failure of the feedback path in the vertical scan current signal source. A controllable kinescope driver circuit, coupled to the kinescope, the horizontal scan detector, the vertical scan detector and the vertical feedback detector, blanks the kinescope if the horizontal scan detector detects a loss of horizontal scanning, the vertical scan detector detects a loss of vertical scanning or the vertical feedback detector detects a failure of the feedback path.

Abstract: A convergence correction circuit, for a cathode ray tube projecting images having keystone, differential sinusoidal and differential right-edge curl distortions, comprises generators for horizontal-rate, generally sinusoidal, 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 sinusoidal and differential right-edge curl distortions.