| 摘要 |
A device for converting a visual display, such as the digits of a gas meter reading, into electrical form without mechanical interference with the meter uses a liquid crystal cell. Each digit is illuminated and the light reflected from it is projected through the cell which is in its scattering, i.e. non-transmissive mode. A coordinate control array (6,10) for the cell sets it successively to a number of states in each of which it is in its transmissive mode for one of the possible digit values. Thus each such state is compared with the level of light reflected from the digit to be converted. The level which most closely corresponds to the digit is assumed to be that for the digit, and this is indicated as its value. The display may include numerals or text. The digits may be read singly or in parallel. The liquid crystal device 1-12 has a light entry point at 2,3 and exit point facing detectors 13. <IMAGE> |
