Ultrasonic transducer

• US 4,881,212 A
• Filed: 10/18/1988
• Issued: 11/14/1989
• Est. Priority Date: 04/25/1986
• Status: Expired due to Fees

• Current Assignee: Yokogawa Medical Systems Limited
• Original Assignee: Yokogawa Medical Systems Limited
• Inventors: Takeuchi, Yasuhito
• Primary Examiner(s): Steinberger, Brian S.
• Application Number:
  US07/270,157
• Time in Patent Office: 392 Days
• Field of Search: 310/334, 310/336, 73/644, 367/140, 367/157, 367/152
• US Class Current: 367/152
• CPC Class Codes: A61B 8/4281 characterised by sound-transmitting media or devices for coupling the transducer to the tissue
• CPC Class Codes: G10K 11/02 Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Abstract

This invention is basically, an ultrasonic transducer that can be configured with good reproducibility, that includes an acoustic impedance matching member that gradually changes the acoustic impedance, and which is characterized by

An acoustic impedance matching member(2) configured with multiple unit layers (21, 22, 23, . . . 2n), each layer being thinner than a quarter-wavelength of an ultrasonic wave, and

each unit layer having a laiminated structure make up of heavy metal(52) and plastic(51) layers with a thickness ratio set between them to change gradually from the unit layer close to the ultrasonic oscillator to the unit layer close to the subject.

Claims

1. An ultrasonic transducer comprising an ultrasonic oscillator device and an acoustic impedance matching member useable in contact with an ultrasonic wave radiating surface, wherein said acoustic impedance matching member consists of

a plurality of layers, each layer being of a thickness less that one-quarter wavelength of an ultrasonic wave and consisting of a sublayer of plastic material and in contact therewith a sublayer of metallic material and arranged so that the sublayer of plastic material alternates with the sublayer of metallic material,

wherein the ratio of thickness of the sublayer of plastic material to the thickness of the sublayer of metallic material of each successive layer of the plurality of layers gradually changes from the said radiation surface to the oscillator device.

2. The transducer of claim 1, wherein said ratio gradually increases from the radiation surface to the oscillator device.

3. The transducer of claim 1, wherein said ratio gradually decreases from the radiation surface to the oscillator device.

4. The transducer of claim 1, wherein said oscillator device includes an acoustic damper.

5. The transducer of claim 1, wherein said plastic material is selected from the group consisting of mylar, polester and polyolefine;

and wherein said metallic material is selected from the group consisting of copper, chromium, nickel, iron, coblat, oxides of the foregoing metals, and nitrides of the foregoing metals.