ULTRASONIC WAVE TRANSMITTER DEVICE, ULTRASONIC WAVE PROPAGATION TIME MEASUREMENT SYSTEM AND ULTRASONIC WAVE PROPAGATION TIME MEASUREMENT METHOD

• US 20120198937A1
• Filed: 10/06/2010
• Published: 08/09/2012
• Est. Priority Date: 10/07/2009
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kajitani, Hiroshi, Miyamoto, Junichi
• Granted Patent: US 9,128,565 B2
• Time in Patent Office: Days
• US Class Current: 73/597
• CPC Class Codes: B06B 1/023 and stepped in amplitude, e.g. square wave, 2-level signal
• CPC Class Codes: B06B 1/0655 of cylindrical shape
• CPC Class Codes: B06B 2201/70 Specific application
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: G10K 11/002 Devices for damping, suppressing, obstructing or conducting sound in acoustic devices G10K1/06 - G10K1/10 take precedence; for electro-mechanical transducers for communication H04R3/002

Abstract

An ultrasonic wave transmitter device includes an ultrasonic wave driving circuit that modulates an ultrasonic wave based on a pseudorandom signal to generate an ultrasonic wave driving signal, and an ultrasonic wave transmitter driven by the ultrasonic wave driving signal to send out an ultrasonic wave signal of a frequency higher than a fundamental frequency of the ultrasonic wave driving signal. The ultrasonic wave transmitter includes a cylindrically-shaped piezoelectric or magnetostrictive element sending out the ultrasonic wave signal and an ultrasonic wave absorber that covers part of a base member holding the piezoelectric or magnetostrictive element.

Claims

1. An ultrasonic wave transmitter device, comprising

an ultrasonic wave driving circuit that modulates an ultrasonic wave based on a pseudorandom signal to generate an ultrasonic wave driving signal;

and

an ultrasonic wave transmitter, that driven by the ultrasonic wave driving signal sends out an ultrasonic wave signal of a frequency higher than a fundamental frequency of the ultrasonic wave driving signal;

the ultrasonic wave transmitter including a cylindrically-shaped piezoelectric or magnetostrictive element that sends out the ultrasonic wave signal, and an ultrasonic wave absorber that covers part of a base member that holds the piezoelectric or magnetostrictive element.

2. The ultrasonic wave transmitter device according to claim 1, wherein

the ultrasonic wave absorber comprises a foaming material.

3. The ultrasonic wave transmitter device according to claim 1, wherein

the ultrasonic wave absorber comprises a fibrous material.

4. The ultrasonic wave transmitter device according to claim 1, wherein

the ultrasonic wave absorber is formed in a cylindrical form surrounding the piezoelectric or magnetostrictive element.

5. The ultrasonic wave transmitter device according to claim 1, wherein

the ultrasonic wave absorber is arranged on a connecting side of a lead wire(s) that delivers electric power for driving the piezoelectric or magnetostrictive element.

6. The ultrasonic wave transmitter device according to claim 1, wherein

the ultrasonic wave absorber is arranged in contact with the piezoelectric or magnetostrictive element.

7. The ultrasonic wave transmitter device according to claim 1, wherein

the ultrasonic wave absorber is arranged in contact with about one-half or less of a height of the piezoelectric or magnetostrictive element.

8. The ultrasonic wave transmitter device according to claim 1, further comprising

a cover;

wherein

the ultrasonic wave absorber is arranged between the piezoelectric or magnetostrictive element and the cover.

9. The ultrasonic wave transmitter device according to claim 1, wherein,

the pseudorandom signal comprises an M-sequence signal.

10. The ultrasonic wave transmitter device according to claim 1, wherein,

the ultrasonic wave driving signal has a frequency of approximately one-half a resonance frequency of the piezoelectric or magnetostrictive element.

11. An ultrasonic wave propagation time measurement system, comprising:

the ultrasonic wave transmitter device according to claim 1;

the ultrasonic wave transmitter device further including;

an electromagnetic wave transmitter that sends out an electromagnetic wave signal indicating transmitting timing;

the ultrasonic wave driving circuit modulating an ultrasonic wave, based on the pseudorandom signal, simultaneously with sending out the electromagnetic wave signal;

an electromagnetic wave receiver that detects the ultrasonic wave signal;

an ultrasonic wave receiver that detects the ultrasonic wave sent out; and

a data processing circuit;

the data processing circuit calculating a value of correlation between the ultrasonic wave signal detected and a model waveform which is the same waveform as that of the ultrasonic wave driving signal;

detecting a principal peak value of the value of correlation calculated; and

calculating ultrasonic wave propagation time from a time point of detection of the electromagnetic wave signal and a time point of detection of the principal peak value.

12. The ultrasonic wave propagation time measurement system according to claim 11, wherein,

the electromagnetic wave transmitter, the ultrasonic wave driving circuit and the ultrasonic wave transmitter are built in an electronic pen.

13. The ultrasonic wave propagation time measurement system according to claim 11, wherein

the electromagnetic wave signal comprises an infrared signal.

15. The ultrasonic wave transmitter device according claim 2, wherein

the ultrasonic wave absorber is formed in a cylindrical form surrounding the piezoelectric or magnetostrictive element.

16. The ultrasonic wave transmitter device according claim 3, wherein

the ultrasonic wave absorber is formed in a cylindrical form surrounding the piezoelectric or magnetostrictive element.

17. The ultrasonic wave transmitter device according to claim 2, wherein

the ultrasonic wave absorber is arranged on a connecting side of a lead wire(s) that delivers electric power for driving the piezoelectric or magnetostrictive element.

18. The ultrasonic wave transmitter device according to claim 3, wherein

the ultrasonic wave absorber is arranged on a connecting side of a lead wire(s) that delivers electric power for driving the piezoelectric or magnetostrictive element.

19. The ultrasonic wave transmitter device according to claim 4, wherein

the ultrasonic wave absorber is arranged on a connecting side of a lead wire(s) that delivers electric power for driving the piezoelectric or magnetostrictive element.

20. The ultrasonic wave transmitter device according to claim 2, wherein

the ultrasonic wave absorber is arranged in contact with the piezoelectric or magnetostrictive element.

14. A method for measuring propagation time of an ultrasonic wave in a system in which an ultrasonic wave transmitter including:

a cylindrically-shaped piezoelectric or magnetostrictive element sending out an ultrasonic wave signal; and

an ultrasonic wave absorber that covers part of a base member holding the piezoelectric or magnetostrictive element is arranged facing an ultrasonic wave receiver adapted to receive ultrasonic wave signal, the method comprising;

sending out an electromagnetic wave signal indicating transmitting timing;

generating an ultrasonic wave driving signal by modulating an ultrasonic wave with a pseudorandom signal simultaneously with sending out of the electromagnetic wave signal;

sending out an ultrasonic wave signal of a frequency higher than a fundamental frequency of the ultrasonic wave driving signal, under driving by the ultrasonic wave driving signal;

detecting the electromagnetic wave signal;

detecting the ultrasonic wave signal sent out; and

calculating a value of correlation between the ultrasonic wave signal detected and a model waveform which is the same waveform as that of the ultrasonic wave driving signal;

detecting a principal peak value of the value of correlation calculated; and

calculating an ultrasonic wave propagation time from a time point of detection of the electromagnetic wave signal and a time point of detection of the principal peak value.