Angle detection sensor with setting of ratio of magnetic forces of rotating magnet and bias magnet

• US 5,148,106 A
• Filed: 06/05/1991
• Issued: 09/15/1992
• Est. Priority Date: 07/06/1990
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ozawa, Hiromasa
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US07/710,634
• Time in Patent Office: 468 Days
• Field of Search: 324/173, 324/174, 324/207.12, 324/207.2, 324/207.21, 324/207.25, 324/252, 338/32 R
• US Class Current: 324/207.21
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

The present invention relates to an angle detection sensor including: a magnetoresistive element in which a bias magnet is laminated on a magnetic pattern resistance layer of a thin film ferromagnetic material, and a permanent magnet fixed to a rotation shaft which rotates about the center of the magnetoresistive element. In particular, when a rotation angle of the permanent magnet is large, a ratio of a first magnetic force of said permanent magnet to a second magnetic force of said bias magnet is set to be smaller than 1, and, when the rotation angle of the permanent magnet is small, the ratio of the first magnetic force of the permanent magnet to the second magnetic force of the bias magnet is set to be larger than 1.

Claims

1. An angle detection sensor comprising:

a planar, magnetoresistive, magnetic field sensing element in which a bias magnet is laminated on a magnetic pattern resistance layer of a thin film ferromagnetic material;

a rotatably supported rotation shaft spaced from said magnetoresistive element and rotatable about a center line of said magnetoresistive element, which center line is orthogonal to the plane of said magnetoresistive element; and

a permanent magnet fixed to said rotation shaft for rotation about said center line of the magnetoresistive element;

wherein when a rotation angle of the permanent magnet is greater than a predetermined amount, a ratio of a first magnetic force of said permanent magnet to a second magnetic force of said bias magnet is set to be smaller than 1; and

wherein when a rotation angle of the permanent magnet is less than a predetermined amount, the ratio of the first magnetic force to the second magnetic force is set to be larger than 1.

2. The angle detection sensor according to claim 1, wherein said permanent magnet comprises a pair of permanent magnets.

3. The angle detection sensor according to claim 1, wherein said predetermined amount is 180°

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4. The angle detection sensor according to claim 2, wherein said predetermined amount is 180°

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5. The angle detection sensor according to claim 1, wherein said permanent magnet is surrounded by protrusions which extend downwardly to surround said magnetoresistive element.