Abstract: An optical encoding system for determing the absolute and the incremental positions of a movable member relative to a stationary member. For example, three stationary light sources may be supported by the stationary member for emitting three narrow light beams on respective paths. An encoding band may be supported by the movable member in the paths of the light beams. The band has a timing and incremental encoding track comprising at least one series of alternating light-blocking stripes and light-passing stripes, and a data track comprising a series of distinct absolute position tags. A read head may be supported by the stationary member and has three optical sensors, one for each light beam, two preferably in quadrature with each other for the timing and incremental encoding track, and one for the data track. Each optical sensor includes light sensors for generating an analog signal voltage.

Abstract: A displacement coder of the differential type wherein, in order to reduce the dimensions thereof, a first disk is rotatably connected to a principal shaft coupled to the shaft which controls the displacement of a mobile member being monitored and a second disk which is coaxially mounted on the principal shaft but which is rotated in a ratio of slightly less than 1 to 1 with respect to the first disk through a driving connection which includes a common pinion and two tooth wheels which wheels are also mounted along the principal shaft.

Abstract: A circuit for an encoder apparatus of an incremental-type construction, including: a unit mechanically joined to a movable machine; a unit for outputting at least two signals having a phase shift and a periodic waveform in response to movement of the unit; a battery-type power supply; and an electric ciruit including a circuit for generating a timing pulse having predetermined frequency and pulse width, a circuit for detecting a change of the signals from the signal outputting circuit and for outputting a pulse signal in response to the change of signals, and a circuit for counting the pulse signal from the signal-change detecting circuit. The apparatus may be optical or magnetic in construction.

Abstract: An incremental position encoder comprising a first member arranged for movement with a second member the movement of which is to be monitored, a plurality of light transmissive or reflective elements of three distinct colors, said elements being arranged in a row on said first member, and the elements being arranged in the row in a repeating sequence of said three colors, a light source directing light to said elements and a color sensitive light detector for receiving light transmitted by, or reflected from said elements, said color sensitive detector being arranged to produce, at any given instant, one of three distinct outputs dependant upon the color of the three available, of the element which is at that instant transmitting or reflecting light from the source to the detector.