Sparse two-dimensional transducer array with compound lens

• US 5,922,962 A
• Filed: 11/04/1996
• Issued: 07/13/1999
• Est. Priority Date: 08/08/1994
• Status: Expired due to Term

• Current Assignee: Diasonics Ultrasound, Inc. (IDB Holding Corporation Limited)
• Original Assignee: Diasonics Ultrasound, Inc. (IDB Holding Corporation Limited)
• Inventors: Tai, Alan Chi-Chung, Towfiq, Farhad, Ishrak, Syed Omar, Pham, Ha Thanh, Salahi, Mehmet
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US08/743,467
• Time in Patent Office: 981 Days
• Field of Search: 73/609, 73/610, 73/612, 73/618, 73/619, 73/620, 73/621, 73/625, 73/626, 73/628, 73/633, 73/641, 73/632, 128/660.01, 128/660.08, 128/661.01, 128/662.03, 367/138, 367/140, 367/153, 367/155, 29/594, 310/335
• US Class Current: 73/632
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: A61B 8/4488 the transducer being a phased array
• CPC Class Codes: A61B 8/4494 characterised by the arrangement of the transducer elements devices for short-range imaging using particular transducer elements arrangements under G01S15/8909; arrangements of transducers in generation of mechanical vibrations of infrasonic, sonic or ultrasonic frequency B06B1/0607
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures
• CPC Class Codes: G10K 11/32 characterised by the shape of the source
• CPC Class Codes: G10K 11/34 using electrical steering of transducer arrays, e.g. beam steering constructional aspects B06B1/0607, B06B1/085

Abstract

A two-dimensional ultrasonic transducer for forming images. The transducer has a plurality of transducer elements for producing ultrasonic bursts in a predetermined manner, and receiving reflected ultrasound from the subject under examination due to the ultrasonic bursts. The plurality of transducer elements are arranged in an array into columns and rows, the columns of the transducer elements arranged in a scanning plane for scanning the subject under examination in order to form a two-dimensional profile of the subject, and the rows of the transducer elements having groups of symmetrically arranged transducer elements being oriented in a elevational plane. Each of the groups of symmetrically arranged transducer elements are mechanically arranged to have a focus at specified locations distant from the transducer which is within the subject under examination. Each of the groups of symmetrically arranged transducer elements coupled to a conductive channels for activating the group of symmetrically arranged transducer elements simultaneously to focus one of the ultrasonic bursts at the specified location from the transducer, and receive signals from the transducer elements due to received ultrasonic echoes due to the ultrasonic bursts. In certain embodiments, the mechanical arrangement of the groups of transducers comprises a lens affixed to the transducer elements in order to focus the ultrasonic bursts at the specified locations.

Claims

1. An ultrasonic transducer comprising:

a. a two-dimensional array of transducer elements arranged into a scanning plane and an elevational plane, wherein a number of elements in said elevational plane is substantially less than a number of said elements in said scanning plane; and

b. a compound lens affixed to said two-dimensional array of transducer elements, said compound lens having a shape which focuses said transducer elements in said elevational plane at more than one predetermined position.

2. The ultrasonic transducer of claim 1 wherein said compound lens comprises a first region to focus a first set of said transducer elements in said elevational plane at a first position, and a second region to focus a second set of said transducer elements in said elevational plane at a second position.

3. The ultrasonic transducer of claim 2 further comprising a time-delayed activation circuit coupled to said two-dimensional array for activating said first set of transducer elements and said second set of transducer elements in a temporally-delayed fashion in said elevational plane in order to focus ultrasonic bursts at a third position.

4. The ultrasonic transducer of claim 3 wherein said third position is between said first position and said second position.

5. The ultrasonic transducer of claim 2 further comprising an apodization circuit for varying the amplitude of activation of said transducer elements on transmission of ultrasonic bursts or reception of ultrasonic echoes due to said ultrasonic bursts in said elevational plane for focusing at said first position and said second position.

6. The ultrasonic transducer of claim 5 wherein said apodization circuit includes a circuit for activating centrally located elements at a higher amplitude than outer elements in said elevational plane of said ultrasonic transducer.

7. The ultrasonic transducer of claim 2 further comprising a frequency control circuit coupled to said two dimensional array of transducer elements for varying the frequency of activation of said transducer elements of said ultrasonic transducer for imaging at said first position and said second position in said elevational plane.

8. The ultrasonic transducer of claim 7 wherein said frequency control circuit comprises a circuit for activating said first group of transducer elements at a first frequency for imaging at said first position, and said first and second groups of transducer elements at a second frequency for imaging at said second position, wherein said second frequency is lower than said first frequency, and said second position is more distant from said transducer than said first position.

9. The ultrasonic transducer of claim 2 wherein said shape of said compound lens in said first region is a portion of a first cylinder having a focus at said first position and said shape of said compound lens in said second region is a portion of a second cylinder having a focus at said second position.

10. The ultrasonic transducer of claim 9 wherein said first cylinder and said second cylinder have a coincident center at a central region of said first cylinder and said second cylinder.

11. The ultrasonic transducer of claim 2 further comprising an activation circuit coupled to said two dimensional array of transducer elements for activating said first set of transducer elements in said elevational plane simultaneously for imaging at said first position, and for activating said first set and said second set of transducer elements in said elevational plane simultaneously for focusing at said second position.

12. The ultrasonic transducer of claim 1 wherein said compound lens includes a plurality of regions each having different shapes for focusing different sets of said transducer elements at different focal zones in said elevational plane wherein a central region in said scanning plane of said compound lens has a shape for focusing for focusing central elements in said array at a first number of focal zones in said elevational plane, and outer regions of said compound lens has a shape for focusing outer regions of said transducer array at a second number of focal zones, wherein said second number is less than said first number.

13. The ultrasonic transducer of claim 1 wherein said compound lens comprises N regions to focus N sets of said transducer elements in said elevational plane at N different positions.

14. An ultrasonic transducer comprising:

a. a two-dimensional array of transducer elements arranged into a scanning plane and an elevational plane, wherein a number of elements in said elevational plane is substantially less than a number of said elements in said scanning plane;

b. a compound lens affixed to said two-dimensional array of transducer elements, said compound lens having a shape which focuses said transducer elements in said elevational plane at more than one fixed focus, wherein said shape of said compound lens comprises a first region for focusing a first set of said transducer elements in said elevational plane at a first position, and a second region for focusing a second set of said transducer elements in said elevational plane at a second position; and

c. a time-delayed activation circuit coupled to said two-dimensional array for activating said first set of transducer elements and said second set of transducer elements in a temporally-delayed fashion in order to focus ultrasonic bursts at a third position, wherein said third position is between said first position and said second position.

15. A sparse two-dimensional ultrasonic transducer for forming images comprising a plurality of transducer elements for producing ultrasonic bursts in a predetermined manner, and receiving reflected ultrasound due to said ultrasonic bursts, said plurality of transducer elements arranged in an array into columns and rows, said rows of said transducer elements arranged in a scanning plane, said columns of said transducer elements having groups of symetrically arranged transducer elements being oriented in a elevational plane, each of said groups of symetrically arranged transducer elements being mechanically arranged to have more than one focus at specified locations distant from said transducer, wherein said mechanical arrangement of said symetrically arranged transducer elements comprises a compound lens, each of said groups of symmetrically arranged transducer elements coupled to a conductive channel for activating said group of symmetrically arranged transducer elements simultaneously to thus focus said ultrasonic bursts at said specified locations, and receive signals from said transducer elements due to received ultrasonic echoes.

16. The sparse two-dimensional ultrasonic transducer of claim 15, wherein said compound lens includes a plurality of regions each having different shapes for focusing different sets of said transducer elements at different focal zones in said elevational plane wherein a central region in said scanning plane of said compound lens has a shape for focusing central elements in said array at a first number of focal zones in said elevational plane, and outer regions of said compound lens have a shape for focusing outer regions of said transducer array at a second number of focal zones.

17. The sparse two-dimensional ultrasonic transducer of claim 16, wherein said second number is less than said first number.