| 摘要 |
1492261 Coded-scale position digitizers SOC D'OPTIQUE PRECISION ELECTRONIQUE ET MECHANIQUE 5 May 1975 [15 May 1974] 18748/75 Heading H3H In a coded-scale position digitizer, a signal with half the cyclic length of the least significant signal derived from the scale is obtained by logically combining the latter with a further signal of the same cyclic length but relatively displaced, this further signal being obtained by logical combination using at least one pair of leading and lagging signals derived from the scale and of greater significance. The resolution of the system is thus doubled. In a pure binary system, one such pair of leading and lagging signals is used, being that of the next-to-least-significant bit, derived from respective tracks or sensors, the EXCL-OR of these signals being EXCL-ORed with the inverse of the signal from the least significant bit track to obtain the signal with half the cyclic length mentioned. In a decimal binary-coded system, two pairs are used with the OR of their respective EXCL-OR replacing the EXCL-OR of the one pair of the purebinary embodiment, the pairs for the mostsignificant and next-to-least-significant bits being used. (In this embodiment, the segment length for the most-significant bit equals that for the next-toleast-significant bit). Conventional lead/lag selection is performed. Variations in light intensity can be compensated for by obtaining each track signal as the difference between the outputs of two sensors half a period apart. |
