Browse Prior Art Database

Improved Legibility of CRT Characters

IP.com Disclosure Number: IPCOM000035767D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Ashbee, WH: AUTHOR

Abstract

This article describes a method to improve the legibility of complex ideographic characters on a high resolution CRT. (Image Omitted)

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 64% of the total text.

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Improved Legibility of CRT Characters

This article describes a method to improve the legibility of complex ideographic characters on a high resolution CRT.

(Image Omitted)

When displaying ideographic characters on a high resolution CRT, legibility becomes a problem with characters having a high number of brush strokes. Switching characteristics of the CRT, along with the aspect ratio of the character, tends to favor the horizontal lines within the character. Characters with high horizontal line content, along with resulting increased intensity, will bleed out single pels within the character.

This article describes a method to balance the intensity between the horizontal and vertical content within each character.

In Fig. 1, the output portion of a video data stream is shown. Video data from a video shift register of N bits is fed to the data input of "D" flip-flop 1. A pel clock, or video oscillator, is fed to the clock input of "D" flip-flop 1. Normally, the flip-flop would then connect to driver 2. Driver 2 would then drive the video input to the CRT.

The problem is solved by implementing a pulse width modulation form of control on the video data line. In Fig. 1, AND circuit 3, "D" flip-flop 4 and delay line 5 are added to the video output circuit, as shown. Timing chart 6 shows the timing relationship for generating the modulated data. The algorithm is such that when two consecutive video data bits are present, the video output is modulated during the period...