ULTRASONIC DETECTION DEVICE AND ULTRASONIC DIAGNOSTIC DEVICE

• US 20120163124A1
• Filed: 10/28/2010
• Published: 06/28/2012
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Akiyama, Takahiro, Takagi, Makoto, Fujii, Kazunari, Mizutani, Hidemasa
• Granted Patent: US 9,314,820 B2
• Time in Patent Office: Days
• US Class Current: 367/87
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 29/2406 Electrostatic or capacitive probes, e.g. electret or cMUT-probes
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046

Abstract

Provided is an ultrasonic detection device including: a capacitive electromechanical transducer including a cell that includes a first electrode and a second electrode disposed so as to oppose with a space; a voltage source for developing a potential difference between the first electrode and the second electrode; and an electric circuit for converting a current, which is caused by a change in electrostatic capacitance between the first electrode and the second electrode due to vibration of the second electrode, into a voltage, in which the capacitive electromechanical transducer provides an output current with a high-pass characteristic having a first cutoff frequency with respect to a frequency, the electric circuit provides an output with a low-pass characteristic having a second cutoff frequency with respect to the frequency, and the second cutoff frequency is smaller than the first cutoff frequency.

Claims

1. An ultrasonic detection device, comprising:

a capacitive electromechanical transducer including a cell that includes a first electrode and a second electrode disposed so as to oppose with a space;

a voltage source for developing a potential difference between the first electrode and the second electrode; and

an electric circuit for converting a current, which is caused by a change in electrostatic capacitance between the first electrode and the second electrode due to vibration of the second electrode, into a voltage,

wherein the capacitive electromechanical transducer provides an output current with a high-pass characteristic having a first cutoff frequency with respect to a frequency,

wherein the electric circuit provides an output with a low-pass characteristic having a second cutoff frequency with respect to the frequency, and

wherein the second cutoff frequency is smaller than the first cutoff frequency.

2. The ultrasonic detection device according to claim 1, wherein the capacitive electromechanical transducer includes a first electrode arranged on a substrate, a second electrode which is disposed so as to be opposed to the first electrode, an insulator and a space held between the first electrode and the second electrode, and a vibrating membrane that vertically vibratably supports the second electrode.

3. The ultrasonic detection device according to claim 1, wherein, in a frequency characteristic of the ultrasonic detection device, a geometric mean of the first cutoff frequency and the second cutoff frequency is in a range of from 0.4 MHz to 1.0 MHz.

4. The ultrasonic detection device according to claim 1, wherein the first electrode and the second electrode constitute respective capacitors including multiple spaces and multiple second electrodes or multiple vibrating membranes, and

wherein a characteristic of the output current of the capacitive electromechanical transducer is determined according to factors including an average of mechanical characteristics of the multiple second electrodes or the multiple vibrating membranes, and electrostatic capacitances of the capacitors.

5. The ultrasonic detection device according to claim 4, wherein the capacitors are arranged two-dimensionally, and wherein vibrating information of the second electrode or the vibrating membrane can be detected two-dimensionally.

6. An ultrasonic diagnostic device, comprising:

the ultrasonic detection device according to claim 1;

a light source; and

a signal processing system that processes a signal detected by the ultrasonic detection device,

wherein light emitted from the light source is applied to an object to be tested, an elastic wave generated by a photoacoustic effect due to the light applied to the object to be tested is detected by the ultrasonic detection device,

and a detection result is processed by the signal processing system to acquire information on the object to be tested.