Other

Asahi Kogaku Kogyo Kabushiki Kaisha

Katsuhiko Kenjo

Masami Shirai

Masato Noguchi

A surveying instrument which incorporates a magnetic incremental rotary encoder includes a rotary magnetic drum provided on an outer peripheral surface thereof with a multi-pole magnetized layer having a plurality of equally-divided magnetized divisions, a pair of magnetic sensors located on opposite sides of said rotary magnetic drum so that each of said pair of magnetic sensors faces said multi-pole magnetized layer, and at least one magnet, positioned in the vicinity of at least one of said pair of magnetic sensors, for reducing an error in detection of said magnetic incremental rotary encoder.

Surveying instrument incorporating a magnetic incremental rotary encoder

An incremental rotary encoder includes a rotary portion, a first sensor and a second sensor, the first and second sensors being arranged so as to be opposite from each other with respect to the axis of the rotary portion. The second sensor is offset from the first sensor so that the phase of output voltage of the second sensor advances or delays with respect to the phase of output voltage of the first sensor by &pgr;/X, wherein &ldquo;X&rdquo; represents a real number of one or more than one.

Incremental rotary encoder, and a surveying instrument incorporating a magnetic incremental rotary encoder

An incremental rotary encoder having first and second sensors which each output two sine wave signals having a phase difference of 90 degrees while a rotary member of the incremental rotary encoder rotates. The incremental rotary encoder includes an absolute-zero-index detecting device, provided for the first sensor; at least one binary coding circuit which codes each of the two sine wave signals and the zero index signal into a corresponding binary signal; a holding device for holding the level data of the binary signal of each sine wave signal output from the second sensor when the absolute-zero-index detecting device outputs the zero index signal; and a controller for determining whether the phase of the two sine wave signals output from the second sensor advances or delays with respect to the phase of the two sine wave signals output from the first sensor.

Incremental rotary encoder

A surveying instrument which incorporates a magnetic incremental rotary encoder includes a rotary magnetic drum provided on an outer peripheral surface thereof with a multi-pole magnetized layer having a plurality of equally-divided magnetized divisions; and at least two magnetic sensors, each of which detects a magnetic field generated by the multi-pole magnetized layer therefrom. Each of the at least two magnetic sensors detects a variation in the magnetic field due to a rotation of the rotary magnetic drum to measure an angle of rotation of the rotary magnetic drum, and the at least two magnetic sensors are arranged so that two of the at least two magnetic sensors are offset from each other to have a phase angle of an odd-numbered pitch angle therebetween.

An incremental rotary encoder outputs two sine wave signals having a phase difference of 90 degrees when the incremental rotary encoder is in operation, the incremental rotary encoder including a binary coding circuit which codes each of the two sine wave signals into a binary signal, a voltage detector which detects the voltage of one of the two sine wave signals at the moment of variation in a signal level of the binary signal, and a controller which includes a calculator which takes an even number of voltage values from each of the two sine wave signals to take an average of the even number of voltage values for each of the two sine wave signals.

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Tokyo, Japan

Katsuhiko Kenjo