Methods for controlling sensitivity of electrostrictive transducers

• US 5,684,243 A
• Filed: 09/11/1996
• Issued: 11/04/1997
• Est. Priority Date: 10/31/1994
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Prater, David M., Adams, Darwin P., Herrick, Benjamin M., Gururaja, Turuvekere R.
• Primary Examiner(s): NOLAND, THOMAS
• Application Number:
  US08/712,015
• Time in Patent Office: 419 Days
• Field of Search: 73/1 DV, 324/601, 128/660.01, 128/662.03
• US Class Current: 73/1.82
• CPC Class Codes: B06B 1/0207 Driving circuits specially adapted for particular applications, see the relevant subclass, e.g. G01; circuits for steering transducer arrays G10K11/34; basic circuits H03
• CPC Class Codes: B06B 2201/20 Application to multi-element transducer
• CPC Class Codes: G01H 3/005 Testing or calibrating of detectors covered by the subgroups of G01H3/00 calibrating geophysical instruments, e.g. seismic receivers G01V13/00
• CPC Class Codes: G01S 7/52019 Details of transmitters
• CPC Class Codes: G01S 7/52023 Details of receivers
• CPC Class Codes: G01S 7/5205 Means for monitoring or calibrating
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously

Abstract

Apparatus and methods for controlling electrostrictive transducer sensitivity in a pulse-echo medical ultrasound system. Certain characteristics of each transducer element are tested after manufacture and recorded on a storage medium. The stored data is then used, along with certain model relations, for monitoring certain operational parameters of the transducer during use, and feedback compensation applied for maintaining the transducer sensitivity substantially constant. The parameters to be monitored may include the temperature, acoustic pressure, input power, and a figure of merit determined from the dielectric constant and coupling coefficient.

Claims

1. A method of controlling the sensitivity of an electrostrictive transducer element in a system that includes the transmit circuit and a bias voltage source, the method comprising the steps of:

(a) monitoring the electrostrictive transducer element for operational parameters indicative of the-acoustic power generated by the transducer element; and

(b) applying feedback compensation in response to the monitoring step.

2. The method of claim 1, wherein step (a) includes determining the capacitance of the transducer element at an unclamped capacitance frequency by sensing a first voltage that is indicative of the capacitance.

3. The method of claim 2, wherein step (a) includes determining a second capacitance of the transducer element at a clamped capacitance frequency by sensing a second voltage that is indicative of an incident signal transmitted to the transducer element and by sensing a third voltage that is indicative of a reflected signal that is reflected by the transducer element.

4. The method of claim 1, wherein step (a) includes determining a second capacitance of the transducer element at a clamped capacitance frequency by sensing a second voltage that is indicative of an incident signal transmitted to the transducer element and by sensing a third voltage that is indicative of a reflected signal that is reflected by the transducer element.

5. The method of claim 1, wherein step (a) monitors a power delivered to the transducer element at an operating frequency by sensing the current delivered to the transducer element and by sensing a voltage at which the transducer operates.