Vector generator using interpolative analog circuits

• US 4,649,506 A
• Filed: 03/12/1984
• Issued: 03/10/1987
• Est. Priority Date: 03/12/1984
• Status: Expired due to Fees

• Current Assignee: Raymond C. Van Den Heuvel
• Original Assignee: Raymond C. Van Den Heuvel
• Inventors: Van den Heuvel, Raymond C.
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): Jablon, Clark A.
• Application Number:
  US06/588,351
• Time in Patent Office: 1,093 Days
• Field of Search: 364/607, 364/608, 364/719, 364/852, 364/521, 340/739, 340/742, 340/738, 315/367
• US Class Current: 708/8
• CPC Class Codes: G09G 1/08 the beam directly tracing characters, the information to be displayed controlling the deflection and the intensity as a function of time in two spatial co-ordinates, e.g. according to a cartesian co-ordinate system

Abstract

Vector (i.e., line) drawings represent the "intelligence" content of images.

A method is disclosed for the gathering of intelligence and the generation of vectors on the screen of a CRT without the usual problems associated with cost and performance.

The Vector Generator itself uses pairs of digital-to-analog converters with a common analog output. This technique is referred to as interpolation. Careful shaping of the complementary reference voltages of the digital-to-analog converters results in constant velocity, transient-free vectors with starting and end points that are accurately controlled. Cumulative (i.e., closure) errors are entirely absent.

Claims

1. A system wherein CRT display means is of an alphanumeric graphic type, also known as a vector generator, and comprising the following combination:

an array of eight identical electronic circuit means for latching and storing digital information consisting of the X and Y coordinates of the position of an object, the X and Y coordinates of the end point of a given vector or straight line segment, the slew rate of said vector and the color or intensity of said vector, there being two such means for the X coordinates of said end point and two for the Y coordinate of said end point, and one such means each for the X position, the Y position, the slew rate and color or intensity;

an arry of seven identical multiplying digital to analog converter means, one for each latching and storing means as above except for the color or intensity information;

means for steering said X and Y coordinate of end point information into one pair of said X and Y latching and storing means when generating odd-numbered vectors and into the remaining pair when generating even-numbered vectors, in such a way that coordinate information is always loaded into the X and Y latching and storing means connected to said multiplying digital to analog converter means whose reference voltage happens to be zero or minimum;

means for generating two complementary, linearly increasing or decreasing reference voltages to be used as references for said four multiplying digital to analog converter means whose digital input is an X or Y coordinate of end point as above;

means for controlling the slew rate of said reference voltages in response to a digital code representative of slew rate as above;

means for generating cathode drive signals for a CRT upon input of a digital code representative of color or intensity as above, there being generated three cathode signals in the case of a color CRT, and only one cathode signal in the case of a monochrome CRT;

means for controlling and adjusting the range of the reference voltages of said four multiplying digital to analog converter means used for the generation of X and Y position voltages in the generation of individual vectors as above;

means for turning "on" the video circuits of said CRT and controlling the time interval during which video is turned "on" to coincide with the time interval during which said reference voltages are in transition between a maximum and a minimum value that can be changed or adjusted for optimum "closure" or angle transition between interconnected vectors;

means for summing analog signals generated at the output of said digital to analog conversion means pertaining to the X axis and converting them into an equivalent horizontal deflection current in the horizontal deflection yoke of said color or monochrome CRT;

identical summing and deflection means for the Y axis or vertical deflection yoke of said color or monochrome CRT.