Abstract: In construction of a displacement detector for an encoder provided with a phase locked loop connected to a detection head facing a scale of the encoder, use of a signal switching circuit allows optimum selection of signals used for generation of a system output signal depending on the speed of the relative movement between the detection head and the scale, thereby assuring generation of the system output signal at high degree of dissolution at any speed of the relative movement. Further, additional use of a parallel/serial converting unit assures high reliability in transmission of the system output signal to external systems.

Abstract: A rotary encoder apparatus of an incremental-type construction, including: a rotary 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 rotation of the rotary unit; a battery-type power supply; and an electric circuit 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.