Gould Inc.

Systems Research Laboratories

Electronic Image Systems, Inc.

Joe A Mays

Richard E Holmes

Michael C Tyler

A high resolution raster display includes a central processor for providing image data, a digital image processing circuit for converting the image data to display signals, and an analog display circuit for converting the display signals to drive signals for driving a CRT to form a color raster display on the screen of the CRT. The digital image processing circuit includes a display memory for storing the image data and a programmable attribute look-up table for storing attribute data. Under the control of the central processor, the image data stored in the display memory is read out and is used to address the attribute look-up table which provides attribute signals as an output. A pixel rate converter reads in the attribute signals at a first rate and outputs analog display signals at a second rate which is much higher than the first rate, with a video bandwidth of up to 210 MHz. The display signals are received by the analog display circuit, and are used to generate drive signals for driving the color guns of the CRT. The central processor is also capable of providing intensity control signals to the analog display circuit so that the intensity level of each of the attributes identified by the attribute signals can be varied. In this manner, the intensity of the various types of features on a display (for example, background, map, weather, flight path, etc.) can be varied independently.

Analog display circuit including a wideband amplifier circuit for a high

In a cathode ray tube display system, correction factors for X and Y position, astigmatism, focus and shading are recorded for preselected locations in digital memory circuits. Those correction factors bordering the actual beam position are selected and are converted to analog form. The correction factors applied to the system are determined by analogue interpolation, that is, the correction factors are combined in proportion to the proximity of the beam relative to those preselected locations where the correction factors were recorded. Use is made of resistance ladders and multiplexers in the interpolation circuits.

Digital waveform generator

In a dual mode CRT deflection circuit, a capacitor for effecting rapid retrace of the CRT beam by means of resonant nonlinear operation is selectively shunted such that beam deflection may be linearly controlled. A bidirectional switch preferably comprising a field effect transistor (FET) is connected in parallel with the capacitor which in turn is connected in series with the deflection coil of the CRT with the series combination being driven by an amplifier in response to beam positioning signals. When the bidirectional switch is activated to shunt the capacitor, the deflection control circuit operates in a linear mode; and when the switch is deactivated, the deflection coil of the CRT interacts with the capacitor for resonant nonlinear operation. A comparator circuit is connected to the output of the amplifier and coupled to the bidirectional switch through an optical coupler to activate and deactivate the switch in response to conditions within the deflection control circuit. Two capacitors and associated FET shunting circuits are provided for bidirectional resonant nonlinear operation, with the deflection coil being connected in series between the two capacitors.

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Xenia, OH, United States of America

Joe A Mays