Position transducer

• US 20010035749A1
• Filed: 03/27/2001
• Published: 11/01/2001
• Est. Priority Date: 03/29/2000
• Status: Active Grant

• Current Assignee: MORI Seiki Company Limited
• Original Assignee: Sony Precision Technology, Inc. (Sony Group Corp.)
• Inventors: Nekado, Yasuo
• Granted Patent: US 6,549,003 B2
• Time in Patent Office: Days
• US Class Current: 324/207.15
• CPC Class Codes: G01D 3/0365 the undesired influence being measured using a separate sensor, which produces an influence related signal
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2033 controlling the saturation of a magnetic circuit by means of a movable element, e.g. a magnet
• CPC Class Codes: G01D 5/24438 Special design of the sensing element or scale
• CPC Class Codes: G01D 5/24476 Signal processing G01D5/2448 - G01D5/24495 take precedence

Abstract

A position transducer including a scale 10 and magnetic sensor 20 consisting of a first sensor unit 22 and second sensor unit 23 disposed in different positions in a direction (Z-direction) perpendicular to a moving direction (X-direction) of the magnetic sensor 20 relative to the scale 10. The first and second sensor units 22 and 23 are driven in phase with each other with a high frequency, and a difference between outputs of these sensor units is determined to detect a relative position of the magnetic sensor 20 to the scale 10.

Claims

1. A position transducer comprising:

means for developing a magnetic field whose strength and direction change correspondingly to a position of the means;

means moved relatively to the magnetic field developing means for detecting a magnetic field developed by the magnetic field developing means and providing an electrical signal corresponding to the detected magnetic field; and

means for detecting a relative position of the magnetic field detecting means to the magnetic field developing means on the basis of the electrical signal provided from the magnetic field developing means;

the magnetic field detecting means consisting of two sensor units each formed from a sensor coil wound on a high permeability core and driven in phase with each other with a high frequency, the two sensor units being disposed in different positions in a direction perpendicular to a moving direction of the magnetic field detecting means relative to the magnetic field developing means; and

the position detecting means detecting a relative position of the magnetic field developing means to the magnetic field developing means by determining a difference between outputs of the two sensor units.

2. The position transducer as set forth in

claim 1

, wherein a magnetic shielding member is provided between the two sensor units.