Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Character Generator for Interlaced Raster Scan Display

IP.com Disclosure Number: IPCOM000089560D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Evans, CW: AUTHOR

Abstract

Fig. 1 shows two examples of a character "B" as formed on a display of the type that has picture frames made up of two interlaced fields. Horizontal lines of the display are indicated by faint lines, and legends along the left side of Fig. 1 show that the lines of field A are interlaced within lines of field B. Faint vertical lines divide each character into a 10 by 14 matrix of points, and a buffer store holds a 1 or 0 bit for each of these points to signify whether an illuminating beam is to be turned on or turned off at the corresponding point on the screen. The buffer may hold one bit for each point on the screen. Alternatively, the buffer can be made only half as large and hold only the bits for the A field, and the same signals can be used for the B field.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 67% of the total text.

Page 1 of 2

Character Generator for Interlaced Raster Scan Display

Fig. 1 shows two examples of a character "B" as formed on a display of the type that has picture frames made up of two interlaced fields. Horizontal lines of the display are indicated by faint lines, and legends along the left side of Fig. 1 show that the lines of field A are interlaced within lines of field B. Faint vertical lines divide each character into a 10 by 14 matrix of points, and a buffer store holds a 1 or 0 bit for each of these points to signify whether an illuminating beam is to be turned on or turned off at the corresponding point on the screen. The buffer may hold one bit for each point on the screen. Alternatively, the buffer can be made only half as large and hold only the bits for the A field, and the same signals can be used for the B field. In this alternative, the characters have the effect of a 5 by 7 matrix of larger squares, as represented by the left-hand character in Fig. 1.

The apparatus of Fig. 2 operates with a buffer that supplies only the signals for the A field, but it generates the signals for the B field in a way that gives a character or other geometric shape a more natural appearance, as the righthand character in Fig. 1 shows. A shift register receives the video signal and produces a one-line delay. Five bits from the preceding line, corresponding to a character width, are available from the output of the delay circuit and from a four-bit shift register. Three bits of th...