The picture elements on a CRT screen are arranged in spatially separate horizontal lines. Because of the scanning of the electron beam, the picture elements of such an inhomogeneous field have different temporal phases. By contrast, in a modulated homogeneous field, the picture elements are identical in phase. Flicker frequency thresholds for these two types of fields were measured as a function of the modulation depth of the stimuli (De Lange curves) . Similar results were obtained under both display conditions, the frequency thresholds for the modulated homogeneous field being somewhat higher. A further experiment showed that the subjective impression of flicker increases rapidly as frequency is reduced to below the critical fusion frequency at which flicker is reported 50% of the time. On the basis of these results, it is argued that flicker thresholds for VDUs can be estimated safely by using modulated homogeneous fields with comparable parameters.
|Number of pages||7|
|Journal||IPO Annual Progress Report|
|Publication status||Published - 1983|