ABSOLUTE POSITION DETECTING DEVICE

摘要

PURPOSE:To expand an absolute position detectable range by arranging plural patterns which vary repeatedly lengthwise at different pitch on a common member with a specific material and providing pattern detection heads closely to the common member. CONSTITUTION:The detection heads 1 and 2 which are fixed mutually in specific arrangement and a rod part 3 which is relatively displaceable while inserted into the heads are provided. The head 1 consists of coils 1A1-1D1 and 1A2-1D2 and the head 2 consists of coils 2A1-2D1 and 2A2-2D2. The 1st pattern formed by providing rings 3a which are made of materials reacting magnetically and have width P/2 lengthwise at intervals P/2 and the 2nd pattern formed by providing wires 3b which are made of materials reacting magnetically and have specific width spirally are both arranged together at the rod part 3. Then, the heads 1 and 2 are excited with a specific AC signal to detect an absolute position with position detection data DX1 in a range of relatively short distance P and with position detection data DX2 in a range of relatively long distance L.