POSITION DETECTOR FOR BURIED OBJECT
Document Type and Number:
Japanese Patent JP3644120
PROBLEM TO BE SOLVED: To achieve a highly accurate detection of positions quickly by providing a sensitivity switching means to automatically switch the sensitivity according to a magnetic detection output value of a magnetic sensor.
SOLUTION: Automatic offset adjustment circuits 7a-7b absorb characteristic differences among magnetic sensors 1a-1b and variations among first stage amplifiers 6a-6b to enhance position detecting accuracy of a permanent magnet and adjusts a biasing voltage outputted from a control circuit 9. The control circuit 9 is initially set to a high sensitivity position and can telling in what direction a position detector should be moved even when the permanent magnet is located at a remote point. But when magnetism is detected beyond a preset level and the sensitivity of the control circuit exceeds its limit, the circuit is automatically switched over a lower sensitivity position. Thus, wren a buried object is located away, the circuit stays at the high sensitivity position and as it approaches the buried object, the circuit is automatically switched to a low sensitivity position, thereby enabling highly accurate detection of positions.
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March 26, 1996
MATSUSHITA ELECTRIC WORKS LTD
G01B7/00; G01R33/02; G01V3/08; G01B7/00; G01R33/02; G01V3/08; (IPC1-7): G01B7/00; G01R33/02; G01V3/08