Sony Corporation

Sony Magnescale Inc.

Yasuhiko Matuyama

Shigeru Ishimoto

Hideo Maejima

A detection circuit for a maximum amplitude value of a 3-phase signal wherein the three phase-signals having a phase difference of 120&deg; from each other is converted to sampling data of digital values by an A/D converter circuit in every sampling period properly decided, and after that, when the coincidence of the values of any two phase-signals among three phase-signals is detected, the value of the remaining one phase-signal is taken as the maximum amplitude value. Thereby, an accurate maximum amplitude value can be obtained.

Detection circuit for maximum value of three phase signal and detection method of the same

A phase adjusting circuit including an input level adjuster using two detection signals having different phases and adjusting an amplitude of at least one detection signal to a predetermined level and a signal processor for signal processing including at least one of addition and subtraction on the two detection signals after level adjustment to generate a pair of output signals having a phase difference of 90 degrees or a single output signal having a phase difference of 90 degrees with respect to one of the detection signals, and a position measuring apparatus including an output level adjuster, a scaling signal generator, a detector, an A/D converter, and a memory in addition, wherein the position measuring apparatus cancels a phase error so that a signal having a phase difference of 90 degrees can be obtained.

Phase adjusting circuit, scaling signal generation circuit using phase adjusting circuit, and position measuring apparatus using scaling signal generation circuit

A position detecting apparatus for a scale measuring system executes a offset correction of the detected three-phase signals A, B and C by using the arithmetic mean (A+B+C)/3 as an offset value. Further, the apparatus executes a gain correction of the offset corrected signals by using a gain which is obtained by the calculation of a square-root of {A.sup.2 +(B-C).sup.2 /3}. Therefore, the accurate measurement is executed by this apparatus even if the gain level is changed at a turn-on of an electric source of this apparatus.

Position detecting apparatus using offset calculated from sum of

An interpolation device for a scale arrangement receives sine wave and cosine wave signals indicative of a measuring data from the scale arrangement and calculates a DC offset value, an amplitude coefficient and an amount of a phase drift on the basis of the received signals. The interpolation device outputs a correct angle signal upon removing a DC offset, a gain level error, a gain unbalance and a phase drift from received signals. Therefore, the interpolation device realizes a mechanical structure of the scale arrangement to be simple.

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Nagasaki, Japan

Yasuhiko Matuyama