Dmg Mori Seiki Co., Ltd.

Yusuke Takei

Masaaki Kusumi

Shigeru Ishimoto

Mitsugu Yoshihiro

Daisuke Uchiyama

A magnetism detecting element detects a leakage magnetism from a scale, on which a magnetic signal with a constant period is recorded, and a relative position between the scale and the magnetism detecting element is detected. The magnetism detecting elements are arranged, along a detection direction of the magnetic signal relative to the scale, in a pattern with a pitch of &#xbd;n (n is a prime number of 3 or more) of a wavelength &#x3bb;' of a signal output by the element. Furthermore, as the pattern for cancelling m odd-order harmonics, the m-th power of 2 magnetism detecting elements are arranged within a range in which a pitch distance L of the magnetism detecting element farthest in the detection direction is expressed by L=(&#x3bb;&#x2032;/2)&#xd7;(&#x2153;+&#x2155;+ 1/7+ . . . 1/(2m+1)).

Position detecting device

A magnetism detecting element detects a leakage magnetism from a scale, on which a magnetic signal with a constant period is recorded, and a relative position between the scale and the magnetism detecting element is detected. The magnetism detecting elements are arranged, along a detection direction of the magnetic signal relative to the scale, in a pattern with a pitch of 1/2n (n is a prime number of 3 or more) of a wavelength &#x3bb;' of a signal output by the element. Furthermore, as the pattern for cancelling m odd-order harmonics, the m-th power of 2 magnetism detecting elements are arranged within a range in which a pitch distance L of the magnetism detecting element farthest in the detection direction is expressed by L=(&#x3bb;&#x2032;/2)&#xd7;(1/3+1/5+1/7+ . . . 1/(2m+1)).

A highly accurate position detection is performed by the use of a magneto-resistance effect element such as a TMR element. At least two magnetic detecting elements-and-are provided to detect leakage magnetism from a scalehaving a magnetic signal magnetically recorded thereon, and to output a recording signal of a position where the leakage magnetism is detected. The at least two magnetic detecting elements-and-are disposed side by side in a direction y perpendicular to a direction x of scanning the scaleand also disposed at positions approximately equidistant from a magnetic signal recording surface of the scale

A position detecting device that includes a recording medium provided with a first recording track in which a non-repetitive signal composed of binary information is recorded and a second recording track in which a signal for specifying a reading section within a section of information of 1 unit for the non-repetitive signal and information reading means that includes a first detection head and a second detection head and for reading each 1 unit information of the non-repetitive signal from the first recording track by using the first detection head in the reading section within a section of information of 1 unit for the non-repetitive signal specified based upon the signal recorded in the second recording track by the second detection head.

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Isehara, Japan

Yusuke Takei