Magnetic sensor for input devices

• US 7,705,586 B2
• Filed: 09/19/2005
• Issued: 04/27/2010
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: van der Hoeven, Jan C., Ruigrok, Jaap, Van Zon, Hans
• Primary Examiner(s): Aurora, Reena
• Application Number:
  US11/576,140
• Publication Number:
  US 20080116885A1
• Time in Patent Office: 1,681 Days
• Field of Search: 324/207.21
• US Class Current: 324/207.21
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01L 1/14 by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
• CPC Class Codes: G01L 5/223 to joystick controls
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/096 anisotropic magnetoresistance sensors
• CPC Class Codes: G05G 2009/04755 Magnetic sensor, e.g. hall generator, pick-up coil
• CPC Class Codes: G11B 5/39 using magneto-resistive devices or effects
• CPC Class Codes: H01F 10/324 Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H03K 2217/96011 with propagation, SAW or BAW

Abstract

In an example embodiment, a magnetic sensor has a magnet and a magneto-resistive, arranged on a substrate such that magnetic field lines through the magneto-resistive element are substantially parallel to a plane of the substrate. Movement of a movable magnetically permeable element MMPE near the substrate is detected as it alters the number of field lines through the element. The MMPE can be more sensitive than devices arranged with perpendicular field lines, and can be easier to manufacture and integrate. Applications include analog pointers, pressure sensors and microphones. The MMPE can use magnets placed either side of the element to detect changes in size of a gap above the element. As the gap closes, less of the parallel oriented field passes through the magneto resistive element.

Claims

1. A magnetic sensor comprising:

a magnetic field generator; and

a magneto-resistive element, arranged on a substrate such that magnetic field lines from the generator passing through the magneto-resistive element are substantially parallel to a plane of the substrate, wherein the magnetic sensor comprises a movable magnetically permeable element which at least partially diverts the magnetic field lines of the magnetic field generator;

the magnetic field generator being arranged on the same side of the substrate as the magneto-resistive element and the magnetic field generator having a pair of magnets on either side of the magneto-resistive element.

2. The sensor as claimed in claim 1, wherein the movable magnetically permeable element is coupled to the substrate to allow a component of movement perpendicular to the plane of the substrate.

3. The sensor as claimed in claim 1, wherein the movable magnetically permeable element is coupled to the substrate to allow a component of movement parallel to the plane of the substrate.

4. The sensor as claimed in claim 1, wherein the movable element (40) comprises a soft magnetic material.

5. The sensor as claimed in claim 1, wherein a magnetic permeability of the movable element is larger than a magnetic permeability of the magneto-resistive element, so that the magnetic field lines from the generator at least partially divert through the magnetically permeable element.

6. The sensor as claimed in claim 1, in which the magneto-resistive element comprises strip portions, the strip portions having a direction substantially perpendicular to the direction of the field lines of the field generator.

7. The sensor as claims in claim 1, the magneto-resistive element arranged in the neighborhood of the movable element to enable sensing of movement of the movable element in any direction parallel to the plane, the magneto-resistance value being indicative for the position of the movable element.

8. The sensor of claim 1, the movable element being pivotable so that a tilt is converted in a movement of part of the movable element in a direction substantially perpendicular to the plane of the magneto-resistive element.

10. The sensor of claim 1, wherein the movable magnetically permeable element functions as a membrane.

11. The sensor as claimed in claim 10 being a pressure sensor.

12. The sensor as claimed in claim 11, being suitable for detecting acoustic waves, to thereby form a microphone.

13. The sensor as claimed in claim 11, being suitable for detecting acceleration forces on the membrane to thereby form an accelerometer.

14. The sensor as claimed in claim 10, being suitable for detecting acoustic waves, to thereby form a microphone.

15. The sensor as claimed in claim 10, being suitable for detecting acceleration forces on the membrane to thereby form an accelerometer.

16. The sensor of claim 1 wherein the pair of magnets of the magnetic field generator are made in thin-film technology.

9. The sensor of 8 being a joystick.

17. A magnetic sensor comprising:

a magnetic field generator; and

a magneto-resistive element, arranged on a substrate such that magnetic field lines from the generator passing through the magneto-resistive element are substantially parallel to a plane of the substrate, wherein the magnetic sensor comprises a movable magnetically permeable element which at least partially diverts the magnetic field lines of the magnetic field generator;

wherein the movable magnetically permeable element is configured as a soft pressure-sensitive membrane.

18. The sensor as claimed in claim 17 being a pressure sensor.

19. The sensor as claimed in claim 17, being suitable for detecting acoustic waves, to thereby form a microphone.

20. The sensor as claimed in claim 17, being suitable for detecting acceleration forces on the membrane to thereby form an accelerometer.