Transducer-based sensor system with multiple drive signal variants

• US 20050258716A1
• Filed: 10/31/2002
• Published: 11/24/2005
• Est. Priority Date: 10/31/2002
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Blakley, Daniel R.
• Granted Patent: US 7,135,806 B2
• Time in Patent Office: Days
• US Class Current: 310/338
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 29/262 by electronic orientation or focusing, e.g. with phased arrays phased arrays per se G10K11/34
• CPC Class Codes: G01N 29/32 Arrangements for suppressing undesired influences, e.g. temperature or pressure variations , compensating for signal noise
• CPC Class Codes: G01N 29/34 Generating the ultrasonic, sonic or infrasonic waves , e.g. electronic circuits specially adapted therefor
• CPC Class Codes: G01N 29/341 with time characteristics
• CPC Class Codes: G01N 29/36 Detecting the response signal , e.g. electronic circuits specially adapted therefor
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency

Abstract

A sensor system including a plurality of transducer groups, with each transducer group having a plurality of transducers. The transducers of each group are adapted to be placed in operative proximity with a sample material. Within each transducer group, each transducer is actuable via application of a different phase-shifted variant of a local oscillator signal to the transducer. The sensor system is also configured so that, for each transducer group, the phase-shifted variants of the local oscillator signal are selectively employed during output processing to inhibit cross-transducer interference occurring between simultaneously active transducers.

Claims

1. A sensor system, comprising:

a plurality of transducer groups, each containing a plurality of transducers configured to be placed in operative proximity with a sample material,

where each transducer within each transducer group is configured to be actuated by receiving a different phase-shifted variant of a local oscillator signal, and

where the sensor system is configured so that the phase-shifted variants of the local oscillator signal are selectively employed during output processing to inhibit cross-transducer interference occurring between simultaneously active transducers.

2. The sensor system of claim 1, where the transducers within each transducer group are movably coupled to a base structure via a mechanical suspension.

3. The sensor system of claim 1, further comprising an oscillator subsystem configured to generate and apply the phase-shifted variants to the transducers within each transducer group, where within each transducer group, a variant shifted by 0°

from the local oscillator signal is applied to a first transducer, a variant shifted by 90°

from the local oscillator signal is applied to a second transducer, a variant shifted by 180°

from the local oscillator signal is applied to a third transducer, and a variant shifted by 270°

from the local oscillator signal is applied to a fourth transducer.

4. The sensor system of claim 3, where each transducer group includes only four transducers.

5. The sensor system of claim 1, where within each transducer group, each of the phase-shifted variants of the local oscillator signal is orthogonal to at least one other of the phase-shifted variants employed within such transducer group.

6. The sensor system of claim 1, where each transducer group includes an output processing subsystem configured to isolate output signals for each of the transducers within such transducer group by filtering out signal contributions caused by other simultaneously active transducers within such transducer group.

7. The sensor system of claim 6, where each output processing subsystem is configured to isolate output signals by employing a frequency-based filter.

8. The sensor system of claim 7, where the frequency-based filter is implemented at least partially with a digital signal processor.

9. The sensor system of claim 8, where the digital signal processor employs linear phase response processing to achieve unwanted signal rejection.

10. The sensor system of claim 6, where each output processing subsystem is configured to isolate output signals by employing a phase-based filter.

11. The sensor system of claim 10, where the phase-based filter is implemented at least partially with a digital signal processor.

12. The sensor system of claim 11, where the digital signal processor employs linear phase response processing to achieve unwanted signal rejection.

13. The sensor system of claim 6, where for each transducer within each transducer group, such transducer is driven by one of the phase-shifted variants, and the same phase-shifted variant is employed within an output signal path of such transducer to facilitate filtering out signal contributions caused by other simultaneously active transducers within such transducer group.

14. The sensor system of claim 13, where each transducer group includes four transducers that are driven by different phase-shifted variants that are respectively phase shifted from the local oscillator signal by 0°

, 90°

, 180° and

270°

.

15. The sensor system of claim 13, where each transducer group includes N transducers that are driven by N corresponding phase-shifted variants that are respectively shifted in phase from the local oscillator signal by 0°

, (1/N*360)°

, (2/N*360)°

. . . and ((N−

1)/N*360)°

.

16. The sensor system of claim 13, where the output processing subsystem includes a digital signal processor configured to filter the noise components in the output signal path.

17. The sensor system of claim 13, where each output processing subsystem includes a digital signal processor configured to process signal components using linear phase methods, and to subtract out-of-phase, steady-state components.

18. A transducer-based sensor method, comprising:

providing multiple different phase-shifted variants of a local oscillator signal to an array of transducers, where such providing includes;

applying a first one of the phase-shifted variants to a first transducer in the array; and

applying a second one of the phase-shifted variants to a second transducer in the array; and

filtering output signals from individual transducers in the array, where such filtering is performed based on at least one of frequency and phase to remove signal components containing cross-transducer noise.

19. The method of claim 18, where providing multiple different phase-shifted variants of a local oscillator signal to an array of transducers further includes:

applying a third one of the phase-shifted variants to a third transducer in the array; and

applying a fourth one of the phase-shifted variants to a fourth transducer in the array.

20. The method of claim 19, where the first, second, third and fourth phase-shifted variants of the local oscillator signal each have a different phase relationship to the local oscillator signal.

21. The method of claim 20, where the first phase-shifted variant of the local oscillator signal is shifted in phase by 0°

from the local oscillator signal, the second phase-shifted variant of the local oscillator signal is shifted in phase by 90°

from the local oscillator signal, the third phase-shifted variant of the local oscillator signal is shifted in phase by 180°

from the local oscillator signal, and the fourth phase-shifted variant of the local oscillator signal is shifted in phase by 270°

from the local oscillator signal.

22. The method of claim 18, where the transducer array includes a plurality of transducer groups, each including a plurality of transducers, and where the providing and applying steps are performed at each of the transducer groups.

23. The method of claim 18, further comprising filtering outputs of the transducers based on frequency to remove cross-transducer noise components and thereby obtain separate noise-free output signals corresponding to the first and second transducers.

24. The method of claim 18, further comprising using the phase-shifted variants of the local oscillator signal to process output signals produced by the first and second transducers.

25. The method of claim 24, where using the phase-shifted variants of the local oscillator signal to process output signals produced by the first and second transducers includes:

using the first phase-shifted variant to process output from the first transducer; and

using the second phase-shifted variant to process output from the second transducer.

26. The method of claim 18, where providing multiple different phase-shifted variants of a local oscillator signal to an array of transducers is performed so that each of the phase-shifted variants is orthogonal to at least one of the other phase-shifted variants.

27. A transducer-based sensor system, comprising:

a transducer array including a plurality of transducers configured to be placed into operative proximity to a sample material;

an oscillator network operatively coupled with the transducer array and configured to apply phase-shifted variants of a local oscillator signal to the plurality of transducers, where at least some of the plurality of transducers are actuated with different phase-shifted variants of the local oscillator signal; and

an output processing subsystem configured to filter output signals received from individual transducers in the transducer array, where the output processing subsystem is configured to perform such filtering based on frequency to remove cross-transducer noise components from such output signals.

28. The sensor system of claim 27, further comprising a base structure and a mechanical suspension movably coupling the plurality of transducers to the base structure.

29. The sensor system of claim 27, where the oscillator network is configured to generate and apply the phase-shifted variants to the transducers, and where the oscillator network is configured to apply a variant shifted by 0°

from the local oscillator signal to a first transducer, a variant shifted by 90°

from the local oscillator signal to a second transducer, a variant shifted by 180°

from the local oscillator signal to a third transducer, and a variant shifted by 270°

from the local oscillator signal to a fourth transducer.

30. The sensor system of claim 29, where the transducer array includes a plurality of transducer groups, each including four transducers, and where the oscillator network is configured to respectively apply a 0°

variant, 90°

variant, 180°

variant and 270°

variant to the four transducers within each transducer group.

31. The sensor system of claim 27, where each of the phase-shifted variants of the local oscillator signal is orthogonal to at least one other of the phase-shifted variants.

32. The sensor system of claim 27, where the output processing subsystem includes a digital signal processor configured to perform frequency-based filtering on the output signals.

33. The sensor system of claim 27, where the output processing subsystem includes a digital signal processor configured to process signal components using linear phase methods, and to subtract out-of-phase, stead-state components.

34. The sensor system of claim 27, where the transducer array includes a plurality of groups, each including a plurality of transducers.

35. The sensor system of claim 34, where for each transducer within each transducer group, such transducer is driven by one of the phase-shifted variants, and the same phase-shifted variant is employed within an output signal path of such transducer to facilitate filtering out signal contributions caused by other simultaneously active transducers within such transducer group.

36. The sensor system of claim 35, where each transducer group includes four transducers that are driven by different phase-shifted variants that are respectively phase shifted from the local oscillator signal by 0°

, 90°

, 180° and

270°

.

37. The sensor system of claim 34, where each transducer group includes N transducers that are driven by N corresponding phase-shifted variants that are respectively shifted in phase from the local oscillator signal by 0°

, (1/N*360)°

, (2/N*360)°

. . . and ((N−

1)/N*360)°

.

38. A transducer-based sensor system, comprising:

means for providing multiple different phase-shifted variants of a local oscillator signal to an array of transducers, where such means includes;

means for applying a first one of the phase-shifted variants to a first transducer in the array; and

means for applying a second one of the phase-shifted variants to a second transducer in the array; and

means for filtering output signals from individual transducers in the array, where such filtering is performed based on at least one of frequency and phase to remove signal components containing cross-transducer noise.