Patent Publication Number: US-2015065883-A1

Title: Probe for ultrasonic diagnostic apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 2013-0103005, filed on Aug. 29, 2013 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 with an improved heat-radiation structure using graphene. 
     2. Description of the Related Art 
     In general, ultrasonic diagnostic apparatuses direct ultrasonic signals from a body surface of an object to a desired region inside a body, and obtain an image related to a monolayer of soft tissue or the bloodstream using the ultrasonic signals reflected from the desired region. The ultrasonic diagnostic apparatuses are relatively small and cheap compared to other diagnostic apparatuses such as X-ray machines, computerized tomography scanners, magnetic resonance imaging scanners, nuclear medicine scanners and the like. The ultrasonic diagnostic apparatuses also have features of displaying images in real time and being highly safe without radiation exposure that may occur in X-ray machines or the like. The ultrasonic diagnostic apparatuses are widely used to examine internal organs such as the heart, abdominal areas, reproductive organs, and gynecological problems. 
     An ultrasonic diagnostic apparatus includes probes to transmit ultrasonic signals to an object to be examined and receive echo signals reflected from the object, to thereby obtain an ultrasonic image of the object. Recently, research and development to make highly efficient, much smaller and much lighter probes are being actively carried out. 
     The current trend is to manufacture smaller probes, however, heat-radiation is a major obstacle. Because the probe has a sealed structure, it is hard to realize a fan-type heat radiation. In addition, a sufficient heat-radiation effect is not obtained by a heat-radiation material made from general metals or alloys. 
     Since a piezoelectric element used for a probe has poor heat tolerance, a functional error may occur when continuously exposed to high temperatures, which may cause malfunction and durability deterioration of the probe. Further, since the probe is used in close contact with an object to be examined, especially human skin, the probe should operate within a certain temperature limit. Therefore, in order to miniaturize probes, the heat radiation problems must be resolved. 
     SUMMARY 
     It is an aspect of the present invention to provide a probe for an ultrasonic diagnostic apparatus with an improved heat-radiation structure using graphene. 
     It is another aspect of the present invention to provide a probe for an ultrasonic diagnostic apparatus capable of blocking electromagnetic waves as well as enhancing heat-radiation effect by attaching graphene to a heat source and a printed circuit board. 
     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 case to form an exterior appearance, a piezoelectric layer provided in the case to generate ultrasonic waves, a backing layer provided at the rear of the piezoelectric layer to prevent the ultrasonic waves from being transmitted backward from the piezoelectric layer, and a heat-radiation unit to radiate heat transmitted from the piezoelectric layer to the outside of the case. The heat-radiation unit includes graphene. 
     The heat-radiation unit may be disposed adjacent to the backing layer. 
     The heat-radiation unit may be attached to an outer surface of the backing layer. 
     The heat-radiation unit may be formed in a plate shape. 
     The heat-radiation unit may extend to cover a printed circuit board disposed beneath the backing layer so as to block electromagnetic waves. 
     The heat-radiation unit may be inserted into the backing layer. 
     The heat-radiation unit may include plural plates which are spaced apart from each other. 
     The heat-radiation unit may include plural plates which are arranged perpendicular to each other in a grid pattern. 
     The heat-radiation unit may include plural plates which are radially arranged. 
     As described above, by attaching graphene having a high thermal conductivity to a heat source of the probe, a surface temperature of the heat source is reduced. 
     Further, in addition to the effective heat radiation, electromagnetic waves may be blocked by attaching graphene to a printed circuit board as well as a heat source by virtue of the electromagnetic-shielding features of graphene. 
    
    
     
       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 view showing an ultrasonic diagnostic apparatus according to an embodiment of the present invention; 
         FIG. 2  is a view showing a probe for an ultrasonic diagnostic apparatus according to the embodiment of the present invention; 
         FIG. 3  is a view showing a probe for an ultrasonic diagnostic apparatus according to a first embodiment of the present invention; 
         FIG. 4  is a view showing a probe for an ultrasonic diagnostic apparatus according to a second embodiment of the present invention; 
         FIG. 5  is a view showing a probe for an ultrasonic diagnostic apparatus according to a third embodiment of the present invention; and 
         FIG. 6  is a view showing a probe for an ultrasonic diagnostic apparatus according to a fourth embodiment 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. 
       FIG. 1  is a view showing an ultrasonic diagnostic apparatus according to an embodiment of the present invention. 
     As shown in  FIG. 1 , an ultrasonic diagnostic apparatus  1  according to an embodiment of the present invention includes a housing  5  configured to generate an image of an object to be examined. A control panel  3  and a display unit  2  to display an image generated based upon echo signals reflected from the object may be mounted to the housing  5 . 
     The ultrasonic diagnostic apparatus may further include a variety of probes  10  to transmit an ultrasonic signal to an object to be examined and receive an echo signal reflected from the object. The probes  10  may be electrically connected to the housing  5  through cables  11  integrally provided at the probes  10  and connectors  6 . 
     Support units  7  are mounted to a bottom of the housing  5  to support the ultrasonic diagnostic apparatus  1 . Each of the support units  7  may include a moving element, such as a wheel, to enable a user to move the ultrasonic diagnostic apparatus  1 . 
       FIG. 2  is a view showing constitutional elements of a probe  10   a  for an ultrasonic diagnostic apparatus according to an embodiment of the present invention. 
     A probe  10   a  includes a main body  100  to transform signals, cases  11  and  12  and a cover  14  to surround the main body  100 , and a handle  17  to be grabbed by an operator. 
     The cases  11  and  12  may include a first case  11  and a second case  12  which are configured to be coupled to each other to cover the lateral surfaces of the main body  100 . The first and second cases  11  and  12  have shapes corresponding to each other. Hereinafter, the structure of the first case  11  will be described. The first case  11  is formed in a convex shape to have an accommodation space thereinside. 
     The first case  11  has an upper portion which is formed widely enough to accommodate the main body  100 , and an upper surface which is formed to be coupled with the cover  14 . The first case  11  is further provided with plural hooks  13  along the lateral surface which is in contact with the second case  12 , thereby engaging the first case  11  with the second case  12 . The first case  11  also has a lower portion which is shaped to form an opening when engaged with the second case  12 , into which the handle  17  is inserted. 
     The cover  14  is engaged with the upper surfaces of the first and second cases  11  and  12 , and covers the upper portion of the main body  100 . The cover  14  may be formed with an opening  15  through which the top surface of the main body  100  is exposed outside. The top surface of the main body  100  exposed through the opening  15  comes into contact with a surface of an object to be diagnosed. 
     The main body  100  may include a piezoelectric layer  24  to generate ultrasonic waves, a backing layer  22  to prevent the ultrasonic waves from being transmitted backward from the piezoelectric layer  24 , a matching layer  26  disposed on the piezoelectric layer  24 , and an acoustic lens  28  disposed on the matching layer  26 . A printed circuit board (PCB)  18 , which is electrically connected to electrode units provided at both lateral surfaces of the piezoelectric layer  24 , may be disposed beneath the backing layer  22 . 
     The electrode units may be made of a highly conductive metal such as gold, silver and copper, or graphite. The PCB may be configured as a flexible printed circuit board (FPCB) capable of supplying signals and electricity. 
     The piezoelectric layer  24  is made of a piezoelectric material capable of receiving electric signals, converting the signals into physical vibration and generating ultrasonic waves. A piezoelectric material is generally defined as a material having piezoelectric effect and converse piezoelectric effect, where it generates voltage if subjected to physical stress and generates physical deformation if voltage is applied thereto. In other words, a piezoelectric material means a material capable of converting electric energy into physical vibration and converting physical vibration into electric energy. 
     The piezoelectric material of the piezoelectric layer  24  may include PZMT single crystal made from a solid solution of Lead Zirconate Titanate (PZT) ceramic, Magnesium Niobate and Titanate. Alternatively, the piezoelectric material of the piezoelectric layer  24  may include PZNT single crystal made from a solid solution of Zinc Niobate and Titanate. 
     The matching layer  26  is disposed on the piezoelectric layer  24 . The matching layer  26  serves to reduce a difference in acoustic impedance between the piezoelectric layer  24  and an object to be examined so that the ultrasonic waves generated from the piezoelectric layer  24  are effectively transmitted to the object. The matching layer  26  may be configured as one or more layers. The matching layer  26  and the piezoelectric layer  24  may be split into a plurality of units, each of which has a certain width, through a dicing process. 
     Although not illustrated in the drawings, a protective layer may be disposed on the matching layer  26 . The protective layer serves to prevent outward flow of high-frequency components, which may be generated from the piezoelectric layer  24 , and to block inflow of external high-frequency signals. In order to protect internal components from water and chemicals used for sterilization, the protective layer may be made by coating or depositing a conductive material on a surface of a waterproof and chemically resistant film. 
     The acoustic lens  28 , which is disposed on the matching layer  26 , comes into direct contact with an object to be examined. The acoustic lens  28  may be shaped convex in the direction of the radiation of ultrasonic waves in order to focus the ultrasonic waves. If the speed of sound of the material of the acoustic lens  28  is lower than the speed of sound in the human body, the acoustic lens  28  may be concave. In this embodiment, as shown in  FIG. 2 , the acoustic lens  28  is convex in the direction of the radiation of ultrasonic waves. 
     The backing layer  22  is disposed beneath the piezoelectric layer  24 . The backing layer  22  serves to absorb ultrasonic waves generated from the piezoelectric layer  24  and block the downward flow of the ultrasonic waves from the piezoelectric layer  24 , thereby preventing image distortion. The backing layer  22  may be configured as plural layers in order to improve the effect of attenuating or blocking the ultrasonic waves. 
     The backing layer  22  is made from an acoustic backing material capable of absorbing the ultrasonic waves generated from the piezoelectric layer  24 . The acoustic backing material may be made by combining metal powders (e.g., tungsten, copper and aluminum), ceramics and carbon allotrope powders using an epoxy resin, and may include rubber. Especially, metals having a high attenuation coefficient may be used for the acoustic backing material. 
     The processes of generating and receiving the ultrasonic waves of the probe  10   a  inevitably cause vibration of the piezoelectric layer  24  and heat associated therewith. Further, as probes have become smaller and smaller, the probes become highly integrated, and accordingly the amount of heat generation has increased. 
     Such heat may not be radiated outside, but transmitted to the acoustic lens  28  of the probe  10   a.  Because the acoustic lens  28  is an element directly contacting the patient&#39;s skin, the internal heat of the probe  10   a  may be transmitted to the patient&#39;s skin and cause a burn. In addition, the heat may cause functional disorder of the components of the probe  10   a,  which may result in negative influence on patient safety and diagnostic images. Accordingly, the probe  10   a  is required to have a structure capable of effectively radiating the heat outside. 
     From such a point of view, the probe  10   a  may include a heat-radiation unit  20  to radiate the internal heat outside. The heat-radiation unit  20  may include graphene having a high thermal conductivity. 
     Graphene is the thinnest layer stripped off from graphite that consists of carbon atoms piled up in a hexagonal beehive shape. Similarly to carbon nanotube (CNT), graphene is a nanomaterial consisting of a single layer of carbon atoms whose atomic number is 6. Graphene has a two-dimensional plane shape with a thickness of 0.2 nm, and has high physical and chemical stabilities. It is also known that graphene conducts electricity over 100 times better than copper and electrons travel over 100 times faster in graphene than in single crystal silicon primarily used for semiconductors. Further, the thermal conductivity of graphene is about 5000 W/mK, which is over twice that of diamond. 
     The heat-radiation unit  20  may be positioned adjacent to the backing layer  22  disposed beneath the piezoelectric layer  24  which may be called a heat source of the probe  10   a.  The heat-radiation unit  20  positioned adjacent to the backing layer  22  may be arranged so as to radiate the heat transmitted to the backing layer  22  from the piezoelectric layer  24  to the outside of the cases  11  and  12 . 
     The heat-radiation unit  20  may be attached to a lateral surface of the main body  100  including the backing layer  22 . The heat-radiation unit  20  may be a thin plate which has the same shape as the lateral surface of the main body  100 . As shown in  FIG. 2 , the heat-radiation unit  20  may include a first heat-radiation element  20   a  and a second heat-radiation element  20   b,  which are respectively attached to both lateral surfaces of the main body  100 . 
     Because the thin plate-shaped first and second heat-radiation elements  20   a  and  20   b  are in close contact with the main body  100 , an additional space for the first and second heat-radiation elements  20   a  and  20   b  inside the cases  11  and  12  may be unnecessary. Further, since the heat-radiation unit  20  has a size corresponding to the whole area of the lateral surface of the main body  100 , a heat radiation area may be enlarged and accordingly heat radiation efficiency may be increased. 
     So as to block electromagnetic waves, the heat-radiation unit  20  may have a size sufficient to cover the PCB  18  disposed beneath the backing layer  22 . An additional device to block electromagnetic waves from the PCB has been necessary in conventional probes for ultrasonic diagnostic apparatuses. However, both heat-radiation and electromagnetic-shielding problems are simultaneously solved in the probe of the present invention by attaching graphene having electromagnetic shielding properties to the whole area of the main body  100 . 
     In order to clearly describe a variety of embodiments of the heat-radiation unit disposed adjacent to the backing layer, the illustration of the other components than the backing layer, the piezoelectric layer, the matching layer and the acoustic lens are omitted in  FIGS. 3 through 6 . 
       FIG. 3  is a view showing a probe for an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. 
     As shown in the drawing, a heat-radiation unit  30  may be attached to outer surfaces of a main body  100   a  of a probe comprising an acoustic lens  38 , a matching layer  36 , a piezoelectric layer  34  and a backing layer  32 . The heat-radiation unit  30  may include a first heat-radiation element  30   a  and a second heat-radiation element  30   b  which are respectively attached to both lateral surfaces of the main body  100   a.    
     The first heat-radiation element  30   a  and the second heat-radiation element  30   b  may be formed in a plate shape capable of being closely attached to the surface of the main body  100   a.  Differently from the heat-radiation unit  20  depicted in  FIG. 2 , the heat-radiation unit  30  in  FIG. 3  may be formed not to extend to a lower portion of the main body  100   a.  That is, graphene is attached only to the region requiring heat radiation. Accordingly, waste of materials is reduced. 
       FIG. 4  is a view showing a probe for an ultrasonic diagnostic apparatus according to a second embodiment of the present invention. 
     As shown in the drawing, a heat-radiation unit  40  may be inserted into a main body  100   b  of a probe comprising an acoustic lens  48 , a matching layer  46 , a piezoelectric layer  44  and a backing layer  42 . The inserted portion of the heat-radiation unit  40  may be fixed by silicon filled in the backing layer  42 . The heat-radiation unit  40  may include plural plates which are spaced apart from each other. The plural plates are made from graphene so as to radiate heat to the outside. 
     The heat-radiation unit  40  depicted in  FIG. 4  includes a first heat-radiation element  40   a,  a second heat-radiation element  40   b  and a third heat-radiation element  40   c  which are spaced apart from each other. Although three plates are illustrated in the drawing as the heat-radiation unit  40 , the number of the plates is not limited to three. The heat-radiation unit  40  may include a proper number of plates to secure spaces for more efficient heat radiation. 
       FIG. 5  is a view showing a probe for an ultrasonic diagnostic apparatus according to a third embodiment of the present invention. 
     As shown in the drawing, a heat-radiation unit  50  may be inserted into a main body  100   c  of a probe comprising an acoustic lens  58 , a matching layer  56 , a piezoelectric layer  54  and a backing layer  52 . In addition to plural plates  50   a,    50   b  and  50   c,  which are identical to the plates  40   a,    40   b  and  40   c  of the heat-radiation unit  40  depicted in  FIG. 4 , the heat-radiation unit  50  in this embodiment may further include plural plates  51  which are spaced apart from each other and arranged perpendicular to the plates  50   a,    50   b  and  50   c.    
     The perpendicularly-arranged plates  50   a,    50   b,    50   c  and  51  are made from graphene so as to radiate heat to the outside. When viewed from above, the perpendicularly-arranged plates  50   a,    50   b,    50   c  and  51  of the heat-radiation unit  50  are arranged in a grid pattern. The perpendicular arrangement of the plates  50   a,    50   b,    50   c  and  51  in a grid pattern may increase the heat-radiation area. 
       FIG. 6  is a view showing a probe for an ultrasonic diagnostic apparatus according to a fourth embodiment of the present invention. 
     As shown in the drawing, a heat-radiation unit  70  may be inserted into a main body  100   d  of a probe comprising an acoustic lens  68 , a matching layer  66 , a piezoelectric layer  64  and a backing layer  62 . The heat-radiation unit  70  may include plural plates which are radially arranged. The plural plates of the heat-radiation unit  70  are made from graphene and extend in a radial direction from a center portion  72 . 
     So as to fit into the main body  100   d,  an outer plate  78  horizontally extending from the center portion  72  may be arranged parallel to a floor, and a middle plate  74  upwardly extending from the center portion  72  may be the shortest of the plural plates. Each of the plural plates is arranged at a regular angle apart from the adjacent ones between the middle plate  74  and the outer plate  78 . 
     The specific shapes of the probe and graphene attached to or inserted into the probe have been described with reference to the drawings, however these are illustrative only and other various shapes of graphene may be used to radiate heat from a probe for an ultrasonic diagnostic apparatus. 
     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.