Ultrasonic sensor

• US 20100242611A1
• Filed: 03/30/2010
• Published: 09/30/2010
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Terazawa, Hidehito
• Granted Patent: US 8,555,724 B2
• Time in Patent Office: Days
• US Class Current: 73/629
• CPC Class Codes: B06B 1/0284 with consecutive, i.e. sequential generation, e.g. with frequency sweep
• CPC Class Codes: B06B 2201/70 Specific application
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 2015/938 in the bumper area radar in bumper area G01S2013/93275; bumper with obstacle sensor of electric or electronic type B60R19/483
• CPC Class Codes: G01S 7/52003 Techniques for enhancing spatial resolution of targets G01S7/52046 takes precedence
• CPC Class Codes: G01S 7/524 Transmitters

Abstract

A single element of an ultrasonic transducer includes at least one combination of an equivalent series capacitor C1, an equivalent series inductor L1, and an equivalent series resistance R1. The ultrasonic transducer further includes an equivalent parallel capacitor C0. An inductor L2 is connected in series between the ultrasonic transducer and the drive circuit. A first resonance frequency of the equivalent series capacitor C1 and the equivalent series inductor L1 is F0. A second resonance frequency determined by at least the equivalent parallel capacitor C0 and the inductor L2 is Fp. A drive circuit drives the ultrasonic transducer while switching the driving frequency of the ultrasonic transducer to one of the resonance frequency F0 and the resonance frequency Fp.

Claims

1. An ultrasonic sensor comprising:

a single element of an ultrasonic transducer including

at least one combination of an equivalent series capacitor C1, an equivalent series inductor L1, and an equivalent series resistance R1, and

an equivalent parallel capacitor C0;

a drive circuit configured to drive the ultrasonic transducer; and

an inductor L2 connected in series between the ultrasonic transducer and the drive circuit,

wherein the drive circuit is configured to switch a driving frequency of the ultrasonic transducer,

a first resonance frequency of the equivalent series capacitor C1 and the equivalent series inductor L1 is F0,

a second resonance frequency determined by at least the equivalent parallel capacitor C0 and the inductor L2 is Fp, and

the drive circuit is configured to drive the ultrasonic transducer while switching the driving frequency to one of the first resonance frequency F0 and the second resonance frequency Fp.

2. The ultrasonic sensor according to claim 1,

wherein the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0 and the inductor L2.

3. The ultrasonic sensor according to claim 1, further comprising:

a capacitor C2 connected in parallel with the ultrasonic transducer,

wherein the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0, the capacitor C2, and the inductor L2.

4. The ultrasonic sensor according to claim 1,

wherein an inductance of the inductor L2 is variable stepwise, and

the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0 and the inductor L2.

5. The ultrasonic sensor according to claim 1, further comprising:

a plurality of capacitors C2 each individually connectable in parallel with the ultrasonic transducer, the plurality of capacitors C2 configured to include an effective capacitor C2 connected in parallel with the ultrasonic transducer, and

the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0, the effective capacitor C2, and the inductor L2.

6. The ultrasonic sensor according to claim 1, further comprising:

a plurality of capacitors C2 each individually connectable in parallel with the ultrasonic transducer, the plurality of capacitors C2 configured to include an effective capacitor C2 connected in parallel with the ultrasonic transducer,

an inductance of the inductor L2 is variable stepwise, and

the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0, the effective capacitor C2, and the inductor L2.

7. An ultrasonic sensor comprising:

a single element of an ultrasonic transducer including

at least one combination of an equivalent series capacitor C1, an equivalent series inductor L1, and an equivalent series resistance R1, and

an equivalent parallel capacitor C0;

a drive circuit configured to drive the ultrasonic transducer; and

a transformer TR connected between the ultrasonic transducer and the drive circuit,

wherein the drive circuit is configured to switch a driving frequency of the ultrasonic transducer,

a first resonance frequency of the equivalent series capacitor C1 and the equivalent series inductor L1 is F0,

a second resonance frequency determined by at least the equivalent parallel capacitor C0 and the transformer TR is Fp, and

the drive circuit is configured to drive the ultrasonic transducer while switching the driving frequency to one of the first resonance frequency F0 and the second resonance frequency Fp.

8. The ultrasonic sensor according to claim 7,

wherein the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0 and the transformer TR.

9. The ultrasonic sensor according to claim 7, further comprising:

a capacitor C2 connected in parallel with the ultrasonic transducer,

wherein the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0, the capacitor C2, and the transformer TR.

10. The ultrasonic sensor according to claim 7,

wherein an inductance component of the transformer TR is variable stepwise, and

the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0 and the transformer TR.

11. The ultrasonic sensor according to claim 7, further comprising:

a plurality of capacitors C2 each individually connectable in parallel with the ultrasonic transducer, the plurality of capacitors C2 configured to include an effective capacitor C2 connected in parallel with the ultrasonic transducer, and

the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0, the effective capacitor C2, and the transformer TR.

12. The ultrasonic sensor according to claim 7, further comprising:

a plurality of capacitors C2 each individually connectable in parallel with the ultrasonic transducer, the plurality of capacitors C2 configured to include an effective capacitor C2 connected in parallel with the ultrasonic transducer,

an inductance component of the transformer TR is variable stepwise, and

the second resonance frequency is a resonance frequency of the equivalent parallel capacitor C0, the effective capacitor C2, and the transformer TR.

13. A method for driving an ultrasonic sensor, the method comprising:

causing a drive circuit to oscillate a single element of an ultrasonic transducer at a driving frequency, the ultrasonic transducer including at least one combination of an equivalent series capacitor C1, an equivalent series inductor L1, and an equivalent series resistance R1, the ultrasonic transducer further including an equivalent parallel capacitor C0, wherein one of an inductor L2 and a transformer TR is connected in series between the ultrasonic transducer and the drive circuit; and

switching the driving frequency to one of a first resonance frequency F0 and a second resonance frequency Fp,

wherein the first resonance frequency F0 is determined by the equivalent series capacitor C1 and the equivalent series inductor L1,

wherein the second resonance frequency Fp is determined by at least the equivalent parallel capacitor C0 and the one of the inductor L2 and the transformer TR.