Apparatus for position detection and verification thereof using pulse

Abstract

An apparatus for position detection using signal patterns created by use of a fixed disk having three conductive patterns disposed thereon. The first and second patterns are annular conductive paths which are concentric with respect to one another and the third pattern consists of radially extending conductive portions which are electrically connected to the second pattern. A brush carried by a rotating member whose position is sought to be determined is maintained in contact with the first and third pattern. In this manner an electrical signal variation is encountered as the radially extending conductive portions are encountered by the brush upon rotation thereof. This variation is thus correlated to the pattern defined on the third pattern. A microprocessor is used to add and subtract signals as the brush is rotated from a reference position based upon an indicia of motor direction. Sequential radially extending conductive portions of said third pattern are arranged into subgroups which provide a unique signature corresponding to the respective position. A sorted positional value is updated as rotation is initiated and after sufficient rotation has occurred to identify a subgroup, a comparison is performed to detect the presence of error. If no error is present the position will continue to be updated; adding and subtracting pulses. If an error is detected, the new subgroup and pulse position therein will be accepted as the correct positional value.