Sony Corporation

Sony Precision Technology Inc.

Eiko Kanbara

Kayoko Taniguchi

Hideaki Tamiya

Nobuo Nabeshima

The present invention provides a displacement detection apparatus uses short scales and can provide a long measurable range comparable to a single long scale with a short bed length. The displacement detection apparatus includes a scale, a first head and a second head adapted to detect periodic analog signals of a plurality of different types, a first processing section and a second processing section that detects the first differential value and the second differential value between the immediately preceding positional data and the current positional data obtained by sampling the periodic analog signals of a plurality of different types, a switching section that selectively switches from the first differential value to the second differential value or vice versa, a scale position detection section that detects the scale getting to a predetermined position relative to the first head or a predetermined position relative to the second head, a switching control section that causes the switching section to switch from either of the differential values to the other in response to the detection of the scale getting to the predetermined position, and an addition section that adds the first differential value or the second differential value selectively switched by the switching control section and outputting it as positional information.

Displacement detection apparatus

A displacement pickup is provided which comprising a scale () having defined thereon a first area () where positional information is recorded with a predetermined pitch and a second area () where positional information is recorded with a pitch different from that in the first area (), a first reader () which reads the positional information recorded in the first area (), a first phase detector () which detects a first phase on the basis of the positional information read by the first reader (), a second reader () which reads the positional information recorded in the second area (), a second phase detector () which detects a second phase on the basis of the positional information read by the second reader (), a phase comparator () which makes a comparison between the first and second phases, and an origin signal selector () which produce a plurality of signals according to the result of comparison and selects an arbitrary one of the plurality of signals on the basis of the positional information read by the first reader ().

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Kanagawa, Japan

Eiko Kanbara