Analysis of Image Smear in CRT Displays Due to Scan Rate and Phosphor Persistence.

摘要

The increase in the use of cathode-ray-tube (CRT) displays for target detection and recognition has placed an emphasis on the ability of these displays to accurately reproduce amplitude and phase information for dynamic targets. This analysis investigates the theoretical dynamic image degradation occurring at the display as a result of the interaction between the target/sensor relative velocity, the CRT system scan rate, and the persistence of the display phosphor. Expressions are developed to allow comparison of phosphors on the basis of modulation loss due to target/sensor motion. A model is developed which equates a target having a spatial frequency (S) and moving with a horizontal speed (V) to a stationary target with a sinusoidal varying intensity of frequency equal to SV. The model identifies phosphor persistence as a major contributor to amplitude modulation loss and predicts several image artifacts such as freezing and apparent motion reversal. Keywords: Image quality; Mathematical models; Limitations; Electrooptics; Line scan. (kr)