Patent Publication Number: US-2013241356-A1

Title: Probe for ultrasonic diagnostic apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims the benefit of Korean Patent Application No. 2012-0025504, filed on Mar. 13, 2012 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Embodiments of the present invention relate to a probe for an ultrasonic diagnostic apparatus that transmits ultrasonic waves to an object to be diagnosed and receives ultrasonic waves reflected by the object. 
     2. Description of the Related Art 
     In general, an ultrasonic diagnostic apparatus is an apparatus that emits ultrasonic waves from the surface of an object to an internal body region of the object to be diagnosed, and acquires tomograms of soft tissues or images of blood flow via the reflected ultrasonic waves. 
     The ultrasonic diagnostic apparatus includes a probe that transmits an ultrasonic signal to an object and receives a signal reflected by the object while remaining in contact with the object. 
     The probe includes a transducer module transmitting and receiving ultrasonic waves as described above. The transducer module includes a piezoelectric device transmitting and receiving ultrasonic waves, a matching layer disposed on the front surface of the piezoelectric device and reducing an acoustic impedance difference between the object and the piezoelectric device, and a backing layer and a backing block sequentially disposed on the rear surface of the piezoelectric device and absorbing ultrasonic waves proceeding in the backward direction of the piezoelectric device. 
     SUMMARY 
     Therefore, it is an aspect of the present invention to provide a probe for an ultrasonic diagnostic apparatus having a transducer module with improved sensitivity. 
     Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     In accordance with one aspect of the present invention, a probe for an ultrasonic diagnostic apparatus includes a transducer module to transmit and receive ultrasonic waves. The transducer module includes a piezoelectric device transmitting and receiving ultrasonic waves, at least one matching layer disposed on the front surface of the piezoelectric device, a backing layer disposed on the rear surface of the piezoelectric device, a backing block disposed on the rear surface of the backing layer, and a gas layer disposed between the backing layer and the backing block. 
     The gas layer may contain air. 
     An acoustic impedance of the backing layer may be greater than an acoustic impedance of the backing block. 
     At least one of the rear surface of the backing layer and the front surface of the backing block may include a gas layer-forming groove to form the gas layer. 
     The gas layer-forming groove may include a first gas layer-forming groove disposed at the rear surface of the backing layer. 
     The first gas layer-forming groove may have a flat inner surface. 
     The first gas layer-forming groove may have a curved inner surface having a depth gradually decreasing from the center to both ends thereof. 
     The gas layer-forming groove may include a second gas layer-forming groove disposed at the front surface of the backing block. 
     The second gas layer-forming groove may have a flat inner surface. 
     The second gas layer-forming groove may have a curved inner surface having a depth gradually decreasing from the center to both ends thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a perspective view illustrating a probe for an ultrasonic diagnostic apparatus according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view illustrating a probe for an ultrasonic diagnostic apparatus according to an embodiment of the present invention; and 
         FIGS. 3 to 7  are cross-sectional views respectively illustrating probes for an ultrasonic diagnostic apparatus according to other embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     Hereinafter, a probe  10  for an ultrasonic diagnostic apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. 
     As illustrated in  FIG. 1 , the probe  10  for an ultrasonic diagnostic apparatus according to the present embodiment includes a housing  11  defining an appearance of the probe  10  and a probe lens  12  disposed at the front end of the housing  11  and contacting a body region of an object to be diagnosed. 
     A transducer module  13  to transmit and receive ultrasonic waves is disposed behind the probe lens  12  in the housing  11 . 
     The transducer module  13  includes a piezoelectric device  131  that transmits ultrasonic waves to the object to be diagnosed and receives ultrasonic waves reflected by the object, matching layers  132 A and  132 B disposed on the front surface of the piezoelectric device  131 , and a backing layer  133  and a backing block  134  sequentially disposed on the rear surface of the piezoelectric device  131 . 
     The piezoelectric device  131  converts electrical energy applied thereto into ultrasonic waves and transmits the ultrasonic waves in the forward direction or receives ultrasonic waves reflected by the object and converts the ultrasonic waves into electrical energy. 
     The matching layers  132 A and  132 B are disposed between the piezoelectric device  131  and the object and reduce an acoustic impedance difference between the piezoelectric device  131  and the object. According to the present embodiment, the matching layers  132 A and  132 B include a first matching layer  132 A and a second matching layer  132 B having different acoustic impedances. When a plurality of matching layers  132 A and  132 B having different acoustic impedances is sequentially aligned as described above, the acoustic impedance difference may be reduced in a stepwise manner. 
     The backing layer  133  and the backing block  134  are respectively formed of materials absorbing ultrasound. Acoustic impedances of the backing layer  133  and the backing block  134  may be the same or may be combined in various ways to obtain a desired acoustic impedance such that, for example, the acoustic impedance of one of the backing layer  133  and the backing block  134  is greater than that of the other. According to the present embodiment, a thickness of the backing layer  133  and the backing block  134  is within a range of λ/8 to λ/2 of a wavelength of ultrasonic waves. 
     In addition, a gas layer  135  filled with a gas is disposed between the backing layer  133  and the backing block  134 . According to the present embodiment, the gas layer  135  is filled with air and a first gas layer-forming groove  133   a  is formed at the rear surface of the backing layer  133  to form the gas layer  135 . According to the present embodiment, the first gas layer-forming groove  133   a  has a flat inner surface, and a thickness of the first gas layer-forming groove  133   a  is in the range of λ/16 to λ/2 of a wavelength of ultrasonic waves. 
     By forming the gas layer  135  between the backing layer  133  and the backing block  134  as described above, acoustic energy proceeding in the backward direction of the piezoelectric device  131  is reflected by the interface between the piezoelectric device  131  and the gas layer  135  toward the piezoelectric device  131  due to acoustic impedance difference between the backing layer  133  and the gas layer  135  and received by the piezoelectric device  131 . As a result, sensitivity of the transducer module  13  is improved. 
     As a result of experiments in which acoustic impedances of the backing layer  133  and the backing block  134  were varied in the transducer module  13  including the gas layer, it was confirmed that sensitivity of the transducer module  13  is improved when the backing layer  133  has a relatively greater acoustic impedance than the backing block  134 . 
     According to the present embodiment, the gas layer  135  is filled with air. However, the disclosure is not limited thereto, and any material that is a gas at room temperature may be used in the gas layer  135 . 
     In addition, the gas layer  135  having a flat inner surface is formed at the rear surface of the backing layer  133  by the first gas layer-forming groove  133   a  according to the present embodiment. However, the disclosure is not limited thereto, and various modifications may be made as shown in  FIGS. 3 to 7 . 
     Referring to  FIG. 3 , the backing layer  133  does not have an element used to form the gas layer  135 . The gas layer  135  is formed by a second gas layer-forming groove  134   a  disposed at the front surface of the backing block  134 . Referring to  FIG. 4 , the transducer module  13  includes a first gas layer-forming groove  133   a  disposed at the rear surface of the backing layer  133  and a second gas layer-forming groove  134   a  disposed at the front surface of the backing block  134  to correspond to the first gas layer-forming groove  133   a.    
     According to the embodiments, the first gas layer-forming groove  133   a  or the second gas layer-forming groove  134   a  have flat inner surfaces. However, the disclosure is not limited thereto. As illustrated in  FIG. 5 , a first gas layer-forming groove  133   a ′ and a second gas layer-forming groove  134   a ′ may be formed to have curved inner surfaces such that depths of the gas layer  135  gradually decrease from the center to both ends thereof. As illustrated in  FIG. 6F , the first gas layer-forming groove  133   a  may have a flat inner surface, and the second gas layer-forming groove  134   a ′ may have a curved inner surface. As illustrated in  FIG. 7 , the first gas layer-forming groove  133   a ′ may have a curved inner surface, and the second gas layer-forming groove  134   a  may have a flat inner surface, and various modifications may also be made. 
     As is apparent from the above description, the probe for an ultrasonic diagnostic apparatus reflects acoustic energy proceeding in the backward direction of the piezoelectric device toward the piezoelectric device by the gas layer disposed between the backing layer and the backing block. Thus, sensitivity of the transducer module  13  is improved. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.