Position detector

• US 6,249,234 B1
• Filed: 07/08/1998
• Issued: 06/19/2001
• Est. Priority Date: 05/14/1994
• Status: Expired due to Term

• Current Assignee: Synaptics (UK) Ltd. (Synaptics Incorporated)
• Original Assignee: Absolute Sensors Limited (Synaptics Incorporated)
• Inventors: Jones, Ross P., Ely, David T. E., Dames, Andrew N., England, James M. C., McKinnon, Alexander W., Howe, Andrew R. L., Pettigrew, Robert M.
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): WONG, ALBERT KANG
• Application Number:
  US09/111,885
• Time in Patent Office: 1,077 Days
• Field of Search: 341/20, 341/116, 341/5, 341/15, 340/870.34, 340/870.37, 336/129, 336/130, 724/207.17, 178/18.06, 178/18.07, 178/19.03, 178/20.04
• US Class Current: 341/20
• CPC Class Codes: G01D 5/2073 by movement of a single coil with respect to two or more coils
• CPC Class Codes: G01D 5/208 using polyphase currents
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A position detector is provided for detecting the relative movement of first and second members which are mounted for relative movement along a measuring path. One of the members comprises a magnetic field generator for generating a magnetic field and the other member comprises first and second conductors which are inductively coupled to said magnetic field generator. The arrangement of the first and second conductors and the magnetic field generator is such that output signals are generated in a first and second receive circuits whose position varies with the relative movement between the two members. In addition to carrying information relating to the relative position between the two members, the signals induced in the receive circuits also comprise information defining the relative orientation of the two movable members, and by suitable processing of the received signals the relative orientation of the two members can also be determined. In a preferred form of the invention, the system operates to define the relative position and orientation of the two movable members in first and second directions from which the relative orientation of the two members in a plane containing the two directions can be determined. The signals induced in the receive circuits can also be processed to give an indication of the gap between the two circuits and to provide an indication of the full relative orientation of the two members.

Claims

1. A position sensor comprising:

first and second sets of windings each set extending in a different direction and each comprising first and second windings;

a magnetic field generator which is adapted to be magnetically coupled to each of said windings, said field generator and said windings being movable relative to each other such that the magnetic coupling between the field generator and each of said windings varies as a function of said movement, for generating a plurality of output signals respectively dependent upon the magnetic coupling between the field generator and the respective said windings;

said magnetic field generator and said windings being adapted so that in use;

(a) the variation in magnetic coupling between said field generator and each of said windings has first and second components which are respectively dependent upon the relative position and the relative tilt of the field generator and the winding in the corresponding direction; and

(b) the first component of said variation in magnetic coupling between said field generator and the first winding of each set has a different spatial frequency from the corresponding variation between the field generator and the second winding in the set;

whereby said relative position and tilt in said different directions may be detected from said plurality of output signals from which the relative rotation of the field generator and the windings may be determined.

2. A position sensor according to claim 1, wherein said magnetic field generator is operable to generate a plurality of magnetic fields in different directions so that the rotation of said magnetic field generator about any axis may be detected from said plurality of output signals.

3. A position sensor according to claim 1, wherein said magnetic field generator is operable to generate a plurality of magnetic fields in different directions so that the rotation of said magnetic field generator about any axis can be determined from said signals induced as a result of the generation of said plurality of magnetic fields by said magnetic field generator.

4. A position sensor according to claim 1, wherein said magnetic field generator comprises a resonator.

5. A position sensor comprising:

first and second sets of windings each set extending in a different direction and each comprising first and second windings;

a plurality of magnetic field generators each of which is adapted to be magnetically coupled to each of said windings, each said field generator and said windings being movable relative to each other such that the magnetic coupling between the field generator and each of said windings varies as a function of said movement, for generating a plurality of output signals respectively dependent upon the magnetic coupling between the field generator and the respective said windings;

each field generator and said windings being adapted so that in use;

(a) the variation in magnetic coupling between said field generator and each of said windings has first and second components which are respectively dependent upon the relative position and the relative tilt of the field generator and the winding in the corresponding direction; and

(b) the first component of said variation in magnetic coupling between said field generator and the first winding of each set has a different spatial frequency from the corresponding variation between the field generator and the second winding in the set;

whereby said relative position and tilt in said different directions of each of said magnetic field generators may be detected from the corresponding plurality of output signals.

6. A position sensor comprising:

first and second sets of windings each set extending in a different direction and each comprising first and second windings;

a magnetic field generator which is adapted to be magnetically coupled to each of said windings, said field generator and said windings being movable relative to each other such that the magnetic coupling between the field generator and each of said windings varies as a function of said movement, for generating a plurality of output signals respectively dependent upon the magnetic coupling between the field generator and the respective said windings;

said magnetic field generator and said windings being adapted so that in use;

(a) the variation in magnetic coupling between said field generator and each of said windings has first and second components which are respectively dependent upon the relative position and the relative tilt of the field generator and the winding in the corresponding direction and a third component which is dependent upon a gap between the field generator and the windings; and

(b) the first component of said variation in the magnetic coupling between said field generator and the first winding of each set has a different spatial frequency from the corresponding variation between the field generator and the second winding in the set;

whereby said relative position and tilt in said different directions and said gap may be detected from said plurality of output signals.

7. A position sensor having two sets of windings each set extending in a different direction and each comprising at least two windings magnetically coupled to a magnetic field generator, and wherein the magnetic coupling between the magnetic field generator and at least two of the windings in each set varies with different spatial frequencies, as a result of which, the relative position and rotation of the magnetic field generator and the windings can be determined from signals induced in a receiver as a result of the generation of a magnetic field by the magnetic field generator.

8. A position sensor having two sets of windings each set extending in a different direction and each comprising at least two windings magnetically coupled to a plurality of magnetic field generators each of which is operable to generate an identifiable magnetic field, and wherein the magnetic coupling between each magnetic field generator and at least two of the windings in each set varies with different spatial frequencies, as a result of which, the position and orientation of each magnetic field generator relative to the sets of windings can be determined from signals induced in a receiver as a result of the generation of a magnetic field by the corresponding magnetic field generator.

9. A position sensor having two sets of windings each set extending in a different direction and each comprising at least two windings magnetically coupled to a magnetic field generator, and wherein the magnetic coupling between the magnetic field generator and at least two of the windings in each set varies with different spatial frequencies, as a result of which, the relative position and orientation of and the gap between the magnetic field generator and the sets of windings can be determined from signals induced in a receiver as a result of the generation of a magnetic field by the magnetic field generator.

10. A position sensor comprising:

first and second sets of windings, each set extending in a different direction and each comprising first and second windings;

a magnetic field generator which is adapted to be magnetically coupled to each of said windings, said field generator and said windings being movable relative to each other;

wherein, in use;

(i) the magnetic coupling between the field generator and each winding in each set of windings varies as a function of their relative position and tilt in the corresponding direction; and

(ii) the first and second windings of each set are arranged so that the variation in magnetic coupling between said field generator and said first winding, as a function of said relative position, has a different spatial frequency from the corresponding variation in magnetic coupling between the field generator and the second winding; and

a receiver comprising (a) means for receiving, in response to a magnetic field being generated by said magnetic field generator, a plurality of output signals respectively dependent upon the magnetic coupling between the field generator and the respective said windings; and

(b) means for processing the received signals associated with each set of windings using said different spatial frequencies, to determine the relative position and tilt of said field generator and said windings in said different directions.

11. A position sensor comprising:

first and second sets of windings each set extending in a different direction and each comprising first and second windings;

a field generator which is adapted to be electromagnetically coupled to each of said windings, said field generator and said windings being movable relative to each other such that the electromagnetic coupling between the field generator and each of said windings varies as a function of said movement, for generating a plurality of output signals respectively dependent upon the electromagnetic coupling between the field generator and the respective said windings;

wherein the variation in electromagnetic coupling between said field generator and each of said windings has first and second components which are respectively dependent upon the relative position and the relative tilt of the field generator and the winding in the corresponding direction, and wherein the first and second windings of each set are arranged so that the first component of said variation in electromagnetic coupling between said field generator and the first winding has a different spatial frequency from the corresponding variation between the field generator and the second winding, whereby said relative position and tilt in said different directions may be detected from said plurality of output signals.