Analog display circuit including a wideband amplifier circuit for a high resolution raster display system

• US 4,803,464 A
• Filed: 02/09/1988
• Issued: 02/07/1989
• Est. Priority Date: 04/16/1984
• Status: Expired due to Fees

• Current Assignee: Gould, Inc. (Transdigm Group Incorporated)
• Original Assignee: Gould, Inc. (Transdigm Group Incorporated)
• Inventors: Holmes, Richard E., Mays, Joe A.
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Brier, Jeffery A.
• Application Number:
  US07/150,486
• Time in Patent Office: 364 Days
• Field of Search: 340/701, 340/703, 340/720, 340/802, 340/793, 340/732, 340/811, 340/814, 358/65, 358/72, 358/184, 358/148
• US Class Current: 345/20
• CPC Class Codes: G09G 1/002 Intensity circuits G09G1/06 - G09G1/28 take precedence
• CPC Class Codes: G09G 5/395 Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen G09G5/399 takes precedence

Abstract

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.

Claims

1. A high speed analog display circuit, coupled to receive a signal for each pixel of an image to be displayed, for driving a cathode ray tube in a raster display system, comprising:

a first multichannel amplifier, a second multichannel amplifier and a third multichannel amplifier, each of said first, second and third multichannel amplifiers comprising;

a plurality of independent signal channels, each of said independent signal channels, comprising;

a digital to analog converter for receiving a low speed intensity control signal, said digital to analog converter producing an analog intensity signal in response to said low speed intensity control signal;

a differential amplifier current switching circuit having a differential amplifier coupled to said digital to analog converter to receive said analog intensity signal therefrom and to produce an output current signal in response to said analog intensity signal;

a differential line pair for receiving a high speed digital attribute data signal;

a switch coupled to said differential line pair and to said differential amplifier enabling or disabling said differential amplifier in response to the presence or absence of the high speed digital attribute data signal on said differential line pair;

means for coupling said output current signals of each of said differential amplifiers in parallel, said coupling means receiving one of said output current signals at a time; and

a current to voltage converter coupled to said coupling means to receive said selected output current signals and to produce an analog voltage chroma signal for driving a cathode ray tube in response thereto.