Abstract: A sensor failure detection circuit for a position encoder, the sensor failure detection circuit receiving from a first set of at least one position sensor position signals which change state at a high resolution and from a second set of at least one position sensor position signals which change state at a lower resolution, the detection circuit monitoring a count for the position signals at the high resolution between states of the position signals at the lower resolution and comparing the count with a predetermined range which represents an expected count for the position signals at the high resolution between the states of the position signals at the lower resolution.

Abstract: A rotatable member is positioned coaxial with a joint between a first element and a second element. The joint defines an angle to be measured. The rotatable member has coded information thereon. First and second sensing heads are attached to respective elements. Coded information is arranged on the rotatable member so as to periodically pass in readable proximity to the sensing heads once every revolution of the rotatable member. A decoding system is provided for each sensing head. Each decoding system includes threshold circuitry, a state machine, and a pulse generator for providing a timing strobe. A first timer uses a timing strobe from the first sensing head for continuously determining the average elapsed time for one complete revolution of the rotatable member. A second timer uses timing strobes from the first and second sensing heads to continuously determine the average elapsed time for the coded information on the rotatable member to travel from the first sensing head to the second head.

Abstract: A signal converter for use with a moveable mechanical device includes input means for receiving a multi-bit digital signal indicative of a position of the moveable mechanical device, a processor having means for converting the multi-bit digital signal into a pulse-width modulated signal, and a low-pass filter that creates an analog voltage corresponding to the position of the moveable mechanical device from the pulse-width modulated signal. A method of creating an analog voltage corresponding to a position of a moveable mechanical device includes the steps of receiving a multi-bit digital signal indicative of the position of the moveable mechanical device, converting the multi-bit digital signal into a pulse-width modulated signal, and creating an analog voltage corresponding to the position of the moveable mechanical device by filtering the pulse-width modulated signal.

Abstract: An encoder includes a code plate, a detector, a transformer, and first and second calculators. The code plate is formed with an absolute pattern including a plurality of bit patterns, each bit pattern formed by a predetermined number of bits and representing one absolute position. The detector moves relatively with respect to the code plate, has a plurality of detecting elements arranged to be opposed to the predetermined number of bits, and reads the bit pattern from the absolute pattern to output a bit pattern signal representing the bit pattern. The transformer can transform only specific bit pattern signals corresponding to specific bit patterns out of a plurality of the bit pattern signals corresponding to the plurality of bit patterns, into the absolute positions. The first calculator calculates a relative, positional relation between the bit pattern corresponding to the bit pattern signal, read from the detector, and the specific bit pattern.

Abstract: A hand-held image scanner can scan an object larger than the scanner itself. Successive multiple partial images scanned in the Y (or longitudinal) direction) are combined to form a single image by keeping track of the position and motion of the scanner in both the Y direction and the X (or latitudinal) direction. The scanner measures distance moved in either the X or the Y direction, but it cannot measure in both directions at once, nor does it scan when it moves in the X direction.

Abstract: A non-contact type potentiometer employing a triangular wave encoder includes a triangular wave encoder for outputting a triangular wave signal consisting of a LEAD signal and a LAG signal having the phases different from each other. A pair of comparators are provided for waveforming the triangular wave signals into a pair of rectangular wave signals. An up/down signal converter is provided for converting each of the rectangular wave signals into up/down directive pulses, and an up/down counter is provided for receiving the directive pulses and outputting an absolute digital signal which is supplied to a D/A converter for converting the absolute digital signal into analog position step signals.

Abstract: An encoder device comprises a first resistor having one end connected to a first contact piece and the other end connected to an A/D conversion input terminal, a second resistor having one end connected to a second contact piece and the other end connected to the other end of the first resistor and having a different resistance value from that of the latter, a first pattern electrode to which a first potential is applied, a second pattern electrode to which a second potential is applied, and a non-electrode zone on which neither of said first and second pattern electrodes is provided.

Abstract: An analog-to-digital converter apparatus has a code board having at least three patterns disposed thereon. One of the patterns represents a least significant bit and is arranged at the center between the other patterns. A reading device is provided for reading the patterns on the code board and for outputting a digital signal corresponding to the patterns. By arranging the least significant pattern in the center, adjustments between the reading device and the code board are not critical, and reading accuracy is improved.

Abstract: An electro-optical displacement sensor comprises an optical source including a plurality of optical grating lines for producing from an incident optical signal a transmitted optical signal having a spatially periodic intensity pattern. Optical sensing means receives the transmitted signal as an input across a plurality of optical receptors, each of which receptors provides an output signal corresponding to the amplitude of the transmitted signal as sensed by the receptor. The receptors are spaced one from the other by a distance different from the fundamental spatial wavelength of the transmitted signal. Signal conditioning means derive a signal vector from the receptor output signals, the signal vector than being processed to derive first and second independent component signals. The component signals are then combined to produce an interpolated phase signal corresponding to the interpolated position of the grating lines relative to the optical receptors.

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.