Device for measuring the position of convergence of the eyes when looking at a visual display unit

摘要

The position of convergence of the eyes can be measured by test equipment with which one of two vernier vision test stimuli are offered to the two eyes separately. This is effected, for example, with polarisation filters. The novel measuring device applied for permits imaging of fusion stimuli and the vernier vision test stimuli on one and the same visual display unit (cathode ray tube). Technically, this is possible by an electronic screen control specially developed for the purpose. This permits fine displacement of the vernier test stimuli by about 1/16th of the picture element distance. This is achieved by a stepped electronic delay of partial images above and below the fusion stimulus as required for convergence measurements. The advantage of this method resides in the fact that the convergence of the eyes can be measured for viewing conditions (viewing distance, contrast, sharpness) that correspond to the real viewing conditions encountered with display screen workstations. Computer-controlled use permits a flexible test design.