PURPOSE: To ensure the escaping action of a measuring piece, prevent erroneous detection, and move a probe at a high speed by arranging a permanent magnet attracting a holder in the exciting direction toward fixed elements and a coil negating the magnetic force of the permanent magnet when brought into contact with it. ;CONSTITUTION: A touch signal probe 25 is fitted to the spindle of a three- dimensional measuring instrument and moved to a measuring object. The attraction of a permanent magnet 36 is added to the elastic exciting force of a coil spring 33, and the support rod 34 of a holder 28 is surely coupled with small balls 32 which are fixed elements even when the probe 25 is moved at a high speed. When a contact ball 30C is brought into contact with the measuring object, a strain gauge 40 detects the strain of a stylus 30B, the contact signal is sent to an exciting circuit to excite the coil 38 of an electromagnet 35, and the magnetic force is generated in the direction to negate the magnetic force of the permanent magnet 36. The exciting force to the small balls 32 is reduced, the escaping action of the holder 28 is ensured at the time of an over-travel, and the damage of the measuring object or erroneous detection can be prevented.;COPYRIGHT: (C)1994,JPO&Japio
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