Zenith Electronics Corporation

Zenith Radio Corporation

Richard W Midland

Boris Rozansky

Thomas W Tepe

An optical interrogation system has camera arrays useful for determining the locations of a plurality of apertures on a flat tension shadow mask and fiducial marks on a screened front panel of a CRT. The system determines the actual location of apertures or fiducial marks with respect to the cameras' field of view. By eliminating gray scaling, the processing only for light/dark transitions in single-bit binary valued pixels from each of the cameras in parallel, i.e., simultaneously, remarkable rapidity is obtained in the interrogation of widely spaced fields with minimal hardware. The system may also be used to interrogate mask support surfaces on the front panel prior to welding the mask thereto.

Optical interprogation system for use in constructing flat tension

A method for use in a raster-scanned electron beam display for displaying an image signal. The image signal is clocked out of a store at a variable clock rate correlated with beam location. The image signal is impressed on the electron beam in order to control image size, position or geometry. The variable clock rate is developed from stored instructions.

Horizontal misconvergence correction system for color video display

A wide band single beam index signal system where the electron beam is operated earlier when positioned to strike an index strip in the presence of video signal corresponding to an immediately prior phosphor stripe and extended when positioned to strike an index strip in the presence of a video signal corresponding to an immediately following phosphor stripe.

Wide band beam index system with improved brightness

A beam index CRT system includes a pair of memories that are selectively operated to store lines of data from a source and to supply stored lines of data to a CRT. A plurality of NOR gates and flip-flops toggle memory addressing means and simultaneously apply appropriate timing signals thereto for controlling the memory writing and reading operations.

Beam index system with switchable memories

A wide-band single beam index signal system includes a photo multiplier tube supplying a decay compensation circuit for developing an output signal responsive to excitation of index strips by the electron beam of the CRT. The output signal is supplied to a differentiator to determine its zero crossing and supplied to a comparator circuit where an index signal pulse is developed. The timing of the index signal is determined by the zero crossing. Video information is clocked from a computer, on a pixel-by-pixel basis, under control of the index signal. The index signal also controls production of a first index video signal and a second index video signal, depending upon the presence or absence of video information. Means are included for turning off the electron beam between index strips. The output of the differentiator is offset for noise compensation. An offset adjustment transistor is included for changing the offset to compensate for the greater excitation of the index strip in the presence of video and to thereby maintain the zero crossing reference.

Beam index system having two distinct levels of index video signal

A wide-band video amplifier-index signal mixer for driving a beam index CRT includes a low power, high speed 'off-the-shelf' video switching transistor having two inputs, one supplied by a first low power, high speed switching transistor coupled to receive video signals and another supplied by a second low power, high speed switching transistor coupled to receive index video signals. Both signals are in digital form. A video gate supplies the first transistor and an index gate supplies the second transistor. Another pair of gates are connected to also supply the video signal to the index gate. Thus, during occurrence of a video signal, both the video gate and the index gate are enabled and both inputs of the video switching transistor are activated.

Video-index signal mixer

A dynamic focusing circuit for a CRT includes a DC coupled parabolic voltage waveform generator having a first capacitor supplied with constant charging current from a transistor for developing a sawtooth voltage waveform thereacross, a first switch transistor for discharging the first capacitor at a horizontal frequency rate, a second capacitor DC coupled to the first capacitor through a voltage-to-current generator transistor for developing a parabolic voltage waveform thereacross and a second switch transistor for discharging the second capacitor in synchronism with the first capacitor. Tilt and amplifier control transistors are DC coupled to the second capacitor. A vertical rate parabolic correction waveform is also developed by similar circuitry. The upper transistor in a cascode amplifier develops a high voltage replica of both the horizontal and vertical parabolic correction waveform voltages for application to the focus electrode of a CRT. Horizontal and a vertical amplifier transistors are coupled in parallel in the lower portion of the cascode amplifier and are supplied with the corresponding parabolic correction voltages.

Parabolic waveform generator

A transformerless switching circuit is described for rapidly turning a horizontal output transistor off and on in response to horizontal rate input pulses. The switching circuit includes a first transistor which is rendered alternately conductive and non-conductive by the input pulses, a second transistor which supplies base drive to the horizontal output transistor in response to the first transistor being conductive, and a third transistor which turns off the horizontal output transistor rapidly in response to the first transistor being non-conductive. The conduction level of the second transistor is controlled by temperature compensating means such that base drive to the horizontal output transistor is varied to compensate for temperature induced current gain changes in the output transistor, thereby holding the latter transistor to a substantially constant saturation current.

Transformerless switching circuit for driving a horizontal output

A color display system includes an index CRT and a photo multiplier tube for developing an index signal in response to electron bombardment of regularly spaced phosphor index strips overlying the screen on the tube. Correction means, including time delayed and inverted blue and red video signals, produce opposite polarity signals that are added to the output of the photo multiplier tube to correct the index signal. A pulse generator produces the square wave index signal. The output of the pulse generator is gated between index pulses for noise purposes.

Index signal enhancement circuit

A display system is disclosed for receiving video data from a character generator and for applying that data to a beam index tube. The system includes a memory for storing data received from the character generator and for outputting the stored data in response to an index clock signal which is derived from a conventional index signal generated by the tube. Output circuitry receives the data from the memory and outputs that data to the tube at the proper times for illuminating phosphors within the tube. The preferred embodiment also drives the tube's beam current in a manner which develops a video image having improved contrast.

Beam index color display system

A billboard video display system comprises a plurality of cathode ray tubes arranged in a predetermined configuration, each of the cathode ray tubes including a viewing screen characterized by a coarse color phosphor pattern. The electron beam generated by each of the cathode ray tubes is scanned across its respective viewing screen and modulated for developing a plurality of color picture elements. The picture elements so produced combine to form a selected billboard video display picture with the picture elements associated with each respective tube representing an unrecognizably small portion thereof.

Billboard large screen TV

This disclosure depicts means for providing greater spot size uniformity across the screen of cathode ray picture tubes. A beam-current-control signal is derived from the horizontal scansion circuit means in which the amplitude of the signal varies monotonically as a function of the distance of the beam spot from the minor axis of the faceplate. Means for receiving the beam-current-control signal for modulating the luminance signal are provided. The beam-current-control signal has such characteristics that the modulation causes a predetermined gradational reduction in beam current at least from the minor axis to the minor sides of the faceplate to inhibit beam spot enlargement in faceplate side zones and thus provide greater spot size uniformity across the screen.

Growing community of inventors

Inverness, IL, United States of America

Richard W Midland