Position detector

• US 4,832,144 A
• Filed: 05/23/1988
• Issued: 05/23/1989
• Est. Priority Date: 05/28/1987
• Status: Expired due to Fees

• Current Assignee: Waco Corporation Kabushiki Kaisha
• Original Assignee: Waco Corporation Kabushiki Kaisha
• Inventors: Takahashi, Kenichi, Tanaka, Takeshi, Taguchi, Yoshinori, Murakami, Azuma, Tomofuji, Yoshiaki
• Primary Examiner(s): Schreyer, Stafford D.
• Application Number:
  US07/197,468
• Time in Patent Office: 365 Days
• Field of Search: 178/18, 178/19, 178/20, 324/207, 324/208, 367/128
• US Class Current: 178/18.07
• CPC Class Codes: G01D 5/247 using time shifts of pulses
• CPC Class Codes: G06F 3/043 using propagating acoustic waves

Abstract

A position detector comprising a plurality of magnetostriction propagating media extending substantially in parallel with one another and having first coils wound about the media at respective first ends thereof and second coils wound around the media over respective lengths thereof. A current pulse is applied to each of the first coils to generate magnetostrictive oscillation waves in the regions of the mediae around which the first coils are wound. The waves propagate through the media and cause an induced voltage to be generated in the respective second coils at the position where position indicators generate a steady magnetic field. The position of the position indicators is determined by measuring the time that elapses between generating the oscillating waves and receiving the induced voltages. Adjacent two of the plurality of magnetotriction propagating media are respectively paired and each of the magnetostriction propagating media of the respective pairs are individually wound with first coils that are connected together and second coils that are connected together so as to generate a magnetostrictive oscillating wave in the respective pairs. The plurality of magnetositriction propagating media may be evenly spaced or may be irregularly arranged with media that separate pairs being closer together than the media that comprise a pair. In one embodiment the current pulse is applied to the second coils to generate magnetostrictive oscillation waves at the position of the position indicators. In this embodiment the waves propagate through the mediae and cause an induced voltage to be generated in the respective first coil.

Claims

1. A position detector comprising:

a plurality of magnetostriction propagating media extending substantially in parallel with one another;

first coils wound around said plurality of magnetostriction propagating media at respective one ends thereof, said one ends defining first regions of said media;

second coils wound around said plurality of magnetostriction propagating media over respective extents thereof;

position indicator means for generating steady magnetic fields located at detected positions of said respective extents defining second regions of said media;

means for applying a current pulse to one of said first coils or second coils to generate magnetostrictive oscillation waves in the corresponding one of said regions of the associated magnetostriction propagating media;

measuring means for measuring the time lapse between the point in time at which said magnetostrictive oscillation wave is generated and the point in time at which said magnetostrictive oscillation wave reaches the other one of said regions after propagation through said media;

processing means responsive to said determined time lapse for determining said positions of said position indicator means; and

wherein adjacent two of said plurality of magnetostriction media are respectively paired, said respective pairs of magnetostriction propagating media being individually wound with said first coils and said second coils so as to simultaneously generate said magnetostrictive oscillation waves in said respective pairs.

2. A position detector as recited in claim 1, wherein said plurality of magnetostriction media are arranged at regular intervals.

3. A position detector as recited in claim 1, wherein each of said paired magnetostriction propagating media is spaced from the adjacent paired magnetostriction propagating media by an interval smaller than that by which the individual magnetostriction propagating media of the respective pairs are spaced from each other.

4. A position detector as recited in claim 1, wherein said first coils have a plurality of turns.

5. A position detector as recited in claim 1, wherein said first coils are crossed at their turn terminals associated with the respective magnetostriction propagating media so that the electric current flowing through said first coils are reversed in its direction at said turn terminals between the portions of said first coils wound around the respective magnetostriction propagating media and the remaining portions thereof.

6. A position detector as recited in claim 1, wherein said plurality of magnetostriction propagating media are divided into a plurality of groups and the adjacent magnetostriction propagating media are respectively paired within each of said groups.

7. A position detector as recited in claim 1, wherein said plurality of magnetostriction propagating media are arranged in a single orientation so as to detect one-dimensional position.

8. A position detector as recited in claim 1, wherein said plurality of magnetostriction propagating media are arranged in orthogonal two directions so as to detect two-dimensional position.