Introduction
Information density in displays in increasing rapidly with thephenomenal growth of data and graphics displays. The introductionof color to data and avionics displays has required improvement ofthe shadow-mask CRT, which heretofore had only limited resolutiondemands place on it, mostly for television use. The colorshadow-mask CRT requires special considerations when measuringresolution to avoid anomalies caused by the physical structure ofthe screen. All of this has renewed interest in display resolutionand resolution measurement.
The resolution of date displays and data-display cathode-raytubes is a most difficult parameter to characterize accurately.Large difference in resolution measurements are often observed, dueto the diversity of display formats, such as raster scan and strokewriting, alphanumerics and graphics. The large diversity ofmeasurement techniques also produces differing results. Differencesin test operator perception and skills and to the problem.Resolution data should therefore be used with caution. Figure 1shows some of the major sources of resolution measurementerror.
When comparing displays or CRTs, the display engineer must besure that resolution data are comparable. A display formmanufacturer A specified as having 20-mil resolution at thehalf-amplitude points with 200-microampere beam current mayactually have better resolution than a display from manufacturer Bspecified as having 10-mil spot size measured with theshrinking-raster technique at 100 microamperes. It’s the age-old”apples-and-oranges” problem again.
The resolution of CRT display may be expressed in any of severalways, including:
• spot size
• line width
• number of TV lines
• modulation depth at a specified spatial frequency
• MTF curve
Each of these measurements has differing connotations ad is notusually directly comparable to the others, especially if drive orduty-cycle differences are considered.
Resolution may be measured in an even greater number of ways, asshown in Figure 2. It is the purpose of this paper to presentinformation on as many techniques as possible.
- Edition:
- 85
- Published:
- 06/01/1985
- Number of Pages:
- 30
- File Size:
- 0 files
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