| 摘要 |
An analog to digital convertor for converting mechanical motion to an electric digital signal which includes a code plate carrying gray codes for measuring displacement, codes for parity bits and parity check control bits and gray code reading means and decoder therefore wherein the parity bits detect the occurrence of a readout error and producing a warning signal while the parity check control bits detect an incorrect parity check caused by errors in the sensing operation such as dirt, dust, or damaged sensing elements, and produces a second warning signal, a memory for temporarily storing the output of the decoder and circuitry inter-connected with the memory and decoder to produce a third warning signal when the difference between the outputs of the memory and the decoder is greater than a predetermined value, circuitry for producing a first error signal when only the second warning signal is present and a second error signal when at least the first and third warning signals are present.
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