Vision testing system for testing the sight function of a patient

Claim 1

A vision testing system for testing the sight functions of a patient, the system comprising: polarization spectacles having first and second polarization lenses for placement in front of the first and second eyes of the patient, respectively; said first polarization lens defining a first polarization axis and said second polarization lens defining a second polarization axis perpendicularly to said first polarization axis; and, a vision testing apparatus including: a light source for radiating light defining a light axis; a first LCD-display mounted on said light axis downstream of said light source and including a plurality of first individually drivable liquid-crystal cells; a second LCD-display mounted on said light axis downstream of said first LCD-display and including a plurality of second individually drivable liquid-crystal cells; the cells of each of said displays being aligned with respect to each other and being adapted to each other with respect to their size; a color-neutral transparent first polarizer mounted on said light axis between said light source and said first LCD-display; a color-neutral transparent second polarizer mounted on said light axis between said first and second LCD-displays; said first polarizer defining a third polarization axis and said second polarizer defining a fourth polarization axis; said third and fourth polarization axes having different directions relative to each other; a first drive circuit for individually driving said cells of said first LCD-display; a second drive circuit for individually driving said cells of said second LCD-display; switching means connected to said first and second drive circuits for controlling both of said first and second drive circuits; and, key pad means for issuing commands to said switching means for driving said first and second drive circuits to, in turn, individually drive the cells of said LCD-displays.