Encoder device for use with polydecade consumption or usage meters

摘要

The encoding wheels associated with successive decades of a polydecade meter are divided into sectors. The rotational positions of each of the said encoding wheels are determined by conventional reading means, which may for example, optically examine tracks of coding that are present around the periphery of a wheel. The sectors are read out in a cyclic Gray code, which is then converted for each decade to a decimal number corresponding to the sector. Ambiguity correction is effected by examining the higher decade in the case of any pair of adjacent decades, and using its value to establish a possible range of the lower decade wheel. The higher decade is defined as the slower moving wheel. The lower decade wheel is then examined to determine whether it falls in the determined range, and thereupon the read value of the coarse wheel (higher decade) is adjusted by plus or minus 1, or allowed to stand, in accordance with the measured lower decade or fine wheel value relative to the cited range. Means are further present, for evaluating the total number of accumulated sectors that have passed a reference point in the case of the lower decade or least significant digit (LSD) wheel, and for then scaling the sectors determined to be cumulatively present on each wheel to decimal values. For purposes of clarity the higher decade is also referred to as the coarse or slower moving wheel, while the lower decade is also called the fine, faster or least significant digit (LSD) wheel.