MULTIPLE AXIS TRANSDUCER WITH MULTIPLE SENSING RANGE CAPABILITY

• US 20080196499A1
• Filed: 02/21/2007
• Published: 08/21/2008
• Est. Priority Date: 02/21/2007
• Status: Active Grant

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Miller, Todd F., Li, Gary G., Monk, David J.
• Granted Patent: US 7,779,689 B2
• Time in Patent Office: Days
• US Class Current: 73/510
• CPC Class Codes: G01D 3/024 for range change; Arrangements for substituting one sensing member by another
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

A transducer package 20 includes a substrate 32 having a first axis of symmetry 36 and a second axis of symmetry 38 arranged orthogonal to the first axis of symmetry 36. At least a first sensor 50 and a second sensor 52 each of which are symmetrically arranged on the substrate 32 relative to one of the first and second axes of symmetry 36 and 38. The first and second sensors 50 and 52 are adapted to detect movement parallel to the other of the first and second axes of symmetry 36 and 38. The first sensor 50 is adapted to detect movement over a first sensing range and the second sensor 52 is adapted to detect movement over a second sensing range, the second sensing range differing from the first sensing range.

Claims

1. A transducer package comprising:

a substrate exhibiting a first axis of symmetry and a second axis of symmetry arranged orthogonal to said first axis of symmetry;

a first sensor; and

a second sensor, each of said first and second sensors being symmetrically arranged on said substrate relative to one of said first and second axes of symmetry and adapted to detect movement substantially parallel to another of said first and second axes of symmetry.

2. A transducer package as claimed in claim 1 wherein:

said first sensor is symmetrically arranged on said substrate relative to said second axis of symmetry such that said another of said first and second axes of symmetry is said first axis of symmetry; and

said second sensor is symmetrically arranged on said substrate relative to said first axis of symmetry such that said another of said first and second axes of symmetry is said second axis of symmetry.

3. A transducer package as claimed in claim 1 wherein said each of said first and second sensors is symmetrically arranged on a common one of said first and second axes of symmetry.

4. A transducer package as claimed in claim 1 wherein said substrate comprises a planar surface, said first and second axes of symmetry are substantially parallel to said planar surface, and said planar surface is balanced at an intersection of said first and second axes of symmetry.

5. A transducer package as claimed in claim 1 wherein said transducer package is symmetrically balanced relative to said first and second axes of symmetry.

6. A transducer package as claimed in claim 1 wherein said each of said first and second sensors comprises:

a proof mass movable laterally with respect to said substrate;

sense fingers extending from said proof mass; and

fixed fingers in non-movable communication with said substrate, said sense fingers and said fixed fingers being longitudinally aligned with said one of said first and second axes of symmetry, and each of said sense fingers being disposed between a pair of said fixed fingers to form a differential capacitive structure.

7. A transducer package as claimed in claim 6 wherein for said each of said first and second sensors, said proof mass, said fixed fingers, and said sense fingers are symmetrically arranged relative to said one of said first and second axes of symmetry.

8. A transducer package as claimed in claim 6 wherein for each said differential capacitive structure, a first one of said pair of fixed fingers and one of said sense fingers produce a first thermally-induced artifact signal, and a second one of said pair of fixed fingers and said one sense finger produce a second thermally-induced artifact signal, said first and second artifact signals have substantially identical characteristics thereby nullifying one another.

9. A transducer package as claimed in claim 1 wherein said transducer package further comprises a third sensor symmetrically arranged on said substrate relative to said second axis of symmetry and adapted to detect said movement substantially parallel to said first axis of symmetry.

10. A transducer package as claimed in claim 9 wherein said transducer package further comprises a fourth sensor symmetrically arranged on said substrate relative to said first axis of symmetry and adapted to detect said movement substantially parallel to said second axis of symmetry.

11. A transducer package as claimed in claim 1 wherein:

said first sensor is adapted to detect said movement over a first sensing range; and

said second sensor is adapted to detect said movement over a second sensing range, said second sensing range differing from said first sensing range.

12. A method of producing a transducer package comprising:

providing a substrate exhibiting a first axis of symmetry and a second axis of symmetry arranged orthogonal to said first axis of symmetry;

symmetrically arranging a first sensor on said substrate about said second axis of symmetry, said first sensor being adapted to detect movement substantially parallel to said first axis of symmetry; and

symmetrically arranging a second sensor on said substrate about said first axis of symmetry, said second sensor being adapted to detect said movement substantially parallel to said second axis of symmetry.

13. A method as claimed in claim 12 further comprising:

configuring said first sensor to detect said movement over a first sensing range; and

configuring said second sensor to detect said movement over a second sensing range, said second sensing range differing from said first sensing range.

14. A method as claimed in claim 12 wherein said symmetrically disposing said first and second sensors comprises:

depositing a conductive layer over said substrate; and

for each of said first and second sensors, patterning said conductive layer to produce a proof mass movable laterally with respect to said substrate, sense fingers extending from said proof mass, and fixed fingers non-movable with respect to said substrate, said sense fingers and said fixed fingers of said first sensor being longitudinally aligned with said second axis of symmetry, said sense fingers and said fixed fingers of said second sensor being longitudinally aligned with said first axis of symmetry, and each of said sense fingers being disposed between a pair of fixed fingers to form a differential capacitive structure.

15. A transducer package comprising:

a substrate having a planar surface and exhibiting a first axis of symmetry and a second axis of symmetry arranged orthogonal to said first axis of symmetry, said first and second axes of symmetry being substantially parallel to said planar surface, and said planar surface being balanced at an intersection of said first and second axes of symmetry.

a first sensor adapted to detect movement over a first sensing range; and

a second sensor adapted to sense said acceleration over a second sensing range, said second sensing range differing from said first sensing range, each of said first and second sensors being symmetrically arranged on said substrate relative to one of said first and second axes of symmetry and adapted to detect movement substantially parallel to another of said first and second axes of symmetry.

16. A transducer package as claimed in claim 15 wherein:

said first sensor is symmetrically arranged on said substrate relative to said second axis of symmetry such that said another of said first and second axes of symmetry is said first axis of symmetry; and

said second sensor is symmetrically arranged on said substrate relative to said first axis of symmetry such that said another of said first and second axes of symmetry is said second axis of symmetry.

17. A transducer package as claimed in claim 16 wherein said transducer package further comprises:

a third sensor symmetrically arranged on said substrate relative to said second axis of symmetry and adapted to detect said movement substantially parallel to said first axis of symmetry; and

a fourth sensor symmetrically arranged on said substrate relative to said first axis of symmetry and adapted to detect said movement substantially parallel to said second axis of symmetry.

18. A transducer package as claimed in claim 17 wherein:

said third sensor is adapted to detect said movement over said second sensing range; and

said fourth sensor is adapted to detect said movement over said first sensing range.

19. A transducer package as claimed in claim 15 wherein:

said first sensor comprises a first proof mass movable laterally with respect to said substrate, first sense fingers extending from said first proof mass, and first fixed fingers in non-movable communication with said substrate, said first sense fingers and said first fixed fingers being longitudinally aligned with said second axis of symmetry, and each of said first sense fingers being disposed between a pair of first fixed fingers to form a first differential capacitive structure; and

said second sensor comprises a second proof mass movable laterally with respect to said substrate, second sense fingers extending from said second proof mass, and second fixed fingers in non-movable communication with said substrate, said second sense fingers and said second fixed fingers being longitudinally aligned with said first axis of symmetry, and each of said second sense fingers being disposed between a pair of said second fixed fingers to form a second differential capacitive structure.

20. A transducer package as claimed in claim 19 wherein:

for each said first differential capacitive structure, a first one of said pair of first fixed fingers and one of said first sense fingers produce a first thermally-induced artifact signal, and a second one of said pair of first fixed fingers and said one first sense finger produce a second thermally-induced artifact signal, said first and second artifact signals have substantially identical characteristics thereby nullifying one another; and

for each said second differential capacitive structure, a first one of said pair of second fixed fingers and one of said second sense fingers produce a third thermally-induced artifact signal, and a second one of said pair of second fixed fingers and said one second sense finger produce a fourth thermally-induced artifact signal, said third and fourth artifact signals have substantially identical characteristics thereby nullifying one another.