Abstract:
Disclosed herein is an ultrasonic probe capable of emitting heat generated by a transducer outside the ultrasonic probe using a heat radiation plate. The ultrasonic probe includes a transducer configured to generate an ultrasonic wave, a heat spreader provided on a surface of the transducer, the heat spreader being configured to absorb heat generated by the transducer, at least one heat radiation plate which contacts at least one side of the heat spreader, and at least one board installed on the at least one heat radiation plate so as to transfer heat generated by the at least one board to the at least one heat radiation plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 2013-0066303, filed on Jun. 11, 2013 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Exemplary embodiments of the present disclosure relate to an ultrasonic probe of an ultrasonic diagnostic apparatus to diagnose diseases. 
         [0004]    2.Description of the Related Art 
         [0005]    An ultrasonic diagnostic apparatus is an apparatus which projects ultrasonic waves from a surface of an object toward a target part inside the object and receives an ultrasonic echo signal reflected therefrom in order to noninvasively obtain a monolayer of soft tissue or an image related to a blood stream. 
         [0006]    The ultrasonic diagnostic apparatus may be small and cheap, and may display diagnostic imaging in real time, compared to other imaging diagnostic devices such as an X-ray device, a CT scanner (computerized tomography scanner), and a nuclear medicine diagnostic device. In addition, since the ultrasonic diagnostic apparatus does not cause radiation exposure, the ultrasonic diagnostic apparatus may be inherently safe. Accordingly, the ultrasonic diagnostic apparatus is widely utilized for cardiac, abdominal, and urologic diagnosis as well as maternity diagnosis. 
         [0007]    The ultrasonic diagnostic apparatus include an ultrasonic probe which projects ultrasonic waves onto an object and receives ultrasonic echo signals reflected from the object in order to image the interior of the object. 
         [0008]    In general, a piezoelectric substance, which converts electric energy into mechanical vibration energy to generate an ultrasonic wave, is widely used as a transducer which generates an ultrasonic wave in the ultrasonic probe. 
         [0009]    A capacitive micromachined ultrasonic transducer (hereinafter, also referred to as “cMUT”), which is a transducer based upon novel concepts, has recently been developed. 
         [0010]    Recently, research and development of a two-dimensional (2D) array transducer has been actively performed, and the cMUT is well suited to be applied to 2D array transducers, thereby facilitating development of a multichannel transducer. 
         [0011]    On the other hand, in a transducer having a small number of channels, a heating value of about 1 W is generated by an electric circuit or the like to drive the probe, and such a heating value may be naturally emitted through a probe casing. However, in a transducer having a large number of channels, an increased heating value of about 7 W is generated, and thus, technologies to radiate and cool the ultrasonic probe are needed. 
       SUMMARY 
       [0012]    Therefore, it is an aspect of the exemplary embodiments to provide an ultrasonic probe capable of emitting heat generated by a transducer outside the ultrasonic probe using a heat radiation plate. 
         [0013]    Additional aspects of the exemplary embodiments 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 exemplary embodiments. 
         [0014]    In accordance with an aspect of an exemplary embodiment, there is provided an ultrasonic probe including a transducer configured to generate an ultrasonic wave, a heat spreader provided on a surface of the transducer, the heat spreader being configured to absorb heat generated by the transducer, at least one heat radiation plate which contacts at least one side of the heat spreader, and at least one board installed on the at least one heat radiation plate so as to transfer heat generated by the at least one board to the at least one heat radiation plate. 
         [0015]    In accordance with another aspect of an exemplary embodiment, there is provided a method of manufacturing an ultrasonic probe, the method including providing a heat spreader on a surface of a transducer, the heat spreader being configured so as to absorb heat generated by the transducer, providing at least one heat radiation plate such that the at least one heat radiation plate contacts at least one side of the heat spreader, and installing at least one board on the at least one heat radiation plate so as to transfer heat generated by the at least one board to the at least one heat radiation plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    These and/or other aspects of the exemplary embodiments will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings of which: 
           [0017]      FIG. 1  is a perspective view illustrating an external appearance of an ultrasonic probe according to an exemplary embodiment; 
           [0018]      FIG. 2  is a perspective view illustrating a structure of the ultrasonic probe of  FIG. 1  with the housing removed; 
           [0019]      FIG. 3  is a perspective view illustrating a structure in which a heat pipe is installed on a heat spreader; 
           [0020]      FIG. 4  is a perspective view illustrating an external appearance of a rear housing of the ultrasonic probe in  FIG. 1 ; 
           [0021]      FIG. 5  is a cross-sectional view taken along direction A-A′ in  FIG. 4 ; 
           [0022]      FIG. 6  is an exploded perspective view illustrating the ultrasonic probe in  FIG. 1 ; 
           [0023]      FIG. 7  is a view illustrating an operation principle of the heat pipe; and 
           [0024]      FIGS. 8 ,  9 ,  10  and  11  are views illustrating a process of manufacturing the ultrasonic probe according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Reference will now be made in detail to the exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
         [0026]      FIG. 1  is a perspective view illustrating an external appearance of an ultrasonic probe according to an exemplary embodiment.  FIG. 2  is a perspective view illustrating a structure of the ultrasonic probe of  FIG. 1 , from which the housing  100  is removed.  FIG. 3  is a perspective view illustrating a structure in which a heat pipe  150  is installed on a heat spreader  140 .  FIG. 4  is a perspective view illustrating an external appearance of a rear housing  110  of the ultrasonic probe in  FIG. 1 . FIG.  5  is a cross-sectional view taken along direction A-A′ in  FIG. 4 .  FIG. 6  is an exploded perspective view illustrating the ultrasonic probe in  FIG. 1 . 
         [0027]    Referring to  FIGS. 1 to 6  and  FIG. 8 , the ultrasonic probe includes a transducer  101 , a heat spreader  140  to absorb heat generated by the transducer  101 , a heat pipe  150  to transfer heat absorbed by the heat spreader  140 , heat radiation plates  120  installed on side surfaces of the heat spreader  140 , boards  130  installed on inner sides of the respective heat radiation plates  120 , and a housing  100  defining an external appearance of the ultrasonic probe. 
         [0028]    According to an exemplary embodiment, a magnetostrictive ultrasonic transducer using a magnetostrictive effect of a magnetic substance which is mainly used in the ultrasonic probe apparatus, a piezoelectric ultrasonic transducer using a piezoelectric effect of a piezoelectric substance, or the like may be utilized as the ultrasonic transducer  101 . In addition, according to an exemplary embodiment, a capacitive micromachined ultrasonic transducer (hereinafter, referred to as “cMUT”) which transmits and receives ultrasonic waves using vibrations of several hundred or thousands of micromachined thin films may also be utilized as the ultrasonic transducer  101 . 
         [0029]    The heat spreader  140  absorbs heat generated by the transducer  101  and is installed on a rear surface of the transducer  101 . The heat spreader  140  may be made of a metal such as aluminum. The heat spreader  140  comes into thermal contact with the transducer  101  to absorb heat generated by the transducer  101 .  FIG. 3  shows a structure of the heat spreader  140  in a case in which the cMUT is used as an example of the transducer  101 . In general, a cMUT array is bonded to an integrated circuit such as an ASIC (application specific integrated circuit) in a flip chip bonding manner, and signal lines of the ASIC to which the cMUT array is bonded may be bonded onto a printed circuit board  141  in a wire bonding manner.  FIG. 3  shows a state in which the heat spreader  140  is installed on the printed circuit board  141 . The heat spreader  140  is installed by being inserted into the printed circuit board  141  to come into thermal contact with the transducer  101 . 
         [0030]    The heat spreader  140  is provided, on a rear surface thereof, with a fixing plate  142  to fix the heat spreader  140  to the printed circuit board  141 . 
         [0031]    The heat spreader  140  may be provided such that the heat spreader  140  comes into direct contact with the transducer  101  or a predetermined gap is defined between the heat spreader  140  and the transducer  101  without direct contact therebetween. The gap between the heat spreader  140  and the transducer  101  may be filled with thermal grease or a phase change material which is a thermal medium having good thermal conductivity. Heat generated by the transducer  101  is directly transferred through the heat spreader  140 , or is transferred to the heat spreader  140  through the thermal grease or the phase change material filled in the gap. 
         [0032]    The heat spreader  140  may be provided with the heat pipe  150  to transfer heat absorbed by the heat spreader  140  in a direction opposite to a direction in which ultrasonic waves are projected, namely, in a z-axis direction. 
         [0033]    The heat spreader  140  may be provided with an insertion groove into which the heat pipe  150  may be inserted, and the heat pipe  150  may be inserted into the insertion groove to be installed on the heat spreader  140 . In order to efficiently transfer heat from the heat spreader  140  to the heat pipe  150 , the insertion groove provided in the heat spreader  140  may have a depth which reaches a thermal contact surface between the heat spreader  140  and the transducer  101 . In other words, the heat pipe  150  may be inserted to such a degree as to reach the thermal contact surface between the heat spreader  140  and the transducer  101 . 
         [0034]      FIG. 7  is a view illustrating an operation principle of the heat pipe  150 . 
         [0035]    The heat pipe  150  is a device, evacuated to a vacuum state, in which a working fluid is injected into a closed pipe-shaped container. 
         [0036]    The working fluid in the heat pipe  150  is present in two phases to transfer heat. 
         [0037]    Referring to  FIG. 7 , when heat is applied to an evaporation portion  21  of the heat pipe  150 , the heat is transferred into the heat pipe  150  by a thermal conductivity via an outer wall. 
         [0038]    In the inside of the heat pipe  150  having high pressure, even low temperatures may cause evaporation of the working fluid to occur on a surface of a wick  23 . 
         [0039]    Gas density and pressure are increased in the evaporation portion  21  due to the evaporation of the working fluid, and thus, a pressure gradient is formed in a gas passage of a central portion of the heat pipe  150  in a direction toward a condensation portion  22  having relatively low density of gas and pressure so as to move a gas. 
         [0040]    In this case, the moving gas is moved in a state of having a large amount of heat of no less than evaporative latent heat. 
         [0041]    The gas moved to the condensation portion  22  dissipates heat while condensing on an inner wall of the condensation portion  22  having a relatively low temperature, and returns back to a liquid phase. 
         [0042]    The working fluid returned to the liquid phase is again moved toward the evaporation portion  21  through pores within the wick  23  by capillary pressure of the wick or gravity. 
         [0043]    Repetition of these processes enables heat transfer to be consistently carried out. 
         [0044]    The evaporation portion  21  of the heat pipe  150  is installed to come into contact with the heat spreader  140  which absorbs heat generated by the transducer  101 , and the heat pipe  150  transfers the heat generated by the transducer  101  to the rear of the ultrasonic probe according to the above-mentioned heat transfer process. The condensation portion  22  of the heat pipe  150  is installed to come into thermal contact with the heat radiation plates  120  (see  FIG. 6 ) which are described later, and thus may also transfer heat to the heat radiation plates  120 . 
         [0045]      FIG. 2  shows that the two heat radiation plates  120  having a shape corresponding to the housing  100  of  FIG. 1  are installed on both sides of the heat spreader  140 . 
         [0046]    The heat radiation plates  120  may be installed on the heat spreader  140  through fastening members, and may emit heat absorbed by the heat spreader  140  into the air. The heat radiation plates  120  have a shape similar to a shape of the housing  100  shown in  FIG. 1 , so that when the housing  100  is installed outside the heat radiation plates  120 , a space between each heat radiation plate  120  and the housing  100  may be minimized and heat radiation efficiency may be improved. 
         [0047]    In addition, the two heat radiation plates  120  serve as frames to which the boards  130  vertically connected to the transducer  101  may be attached as shown in  FIG. 2 , in addition to having heat radiation functions. The heat radiation plates  120  may be made of metal having a high thermal conductivity, such as aluminum or copper. 
         [0048]    The spaces between the heat radiation plates  120  and the housing  100  may be further provided with heat radiation members  160  (see  FIG. 11 ) made of graphite. That is, according to an exemplary embodiment, the two heat radiation members  160  having a shape similar to a shape of each of the heat radiation plates  120  and the housing  100  are respectively installed outside the two heat radiation plates  120 , the housing  100  is installed outside the heat radiation members  160 , and the heat radiation members  160  made of graphite may be installed in the respective spaces between the heat radiation plates  120  and the housing  100 . Graphite is a material having a thermal conductivity more than two times a thermal conductivity of aluminum. The heat radiation members  160  are filled in the spaces between the heat radiation plates  120  and the housing  100 , instead of filling the spaces with air, thereby enabling heat transfer and heat radiation to be more efficiently performed than when the heat radiation members  160  are not present. 
         [0049]    The heat radiation members  160  may be installed to come into contact with a cable extension portion  111  of the rear housing  110  shown in  FIG. 4 . The cable extension portion  111  may be made of a material having a high thermal conductivity to emit heat transferred from the heat radiation members  160  to the outside. 
         [0050]    Each of the boards  130  receives a signal related to driving of the ultrasonic probe through the cable extension portion  111  of the rear housing  110  from a cable connected to the inside of the ultrasonic probe so as to output a signal to control driving of the transducer  101 . 
         [0051]    The board  130  includes a circuit board on which chips to control driving of the ultrasonic probe are mounted. 
         [0052]    The board  130  is electrically connected to the transducer  101  via a flexible printed circuit board or the like so as to output the signal to the transducer  101 . The board  130  may be electrically connected to the circuit board to which the cMUT is mounted and the ASIC is bonded. As described above, the board  130  may be installed inside each heat radiation plate  120  so as to be fixed thereto. 
         [0053]    The rear housing  110  is shown in  FIG. 4 , and is provided with the cable extension portion  111  as described above. The cable, which is electrically connected to the board  130  to output a control signal applied from the outside to the board  130 , extends through the cable extension portion  111  of the rear housing  110 . The cable extension portion  111  is made of a material having a high thermal conductivity, thereby enabling heat transferred from each heat radiation member  160  to be emitted to the outside. 
         [0054]      FIG. 5  is a cross-sectional view cutting the rear housing  110  shown in  FIG. 4  in direction A-A′. As shown in  FIG. 5 , each heat radiation plate  120  may be provided such that a rear end of the heat radiation plate  120  comes into contact with the heat pipe  150 . As shown in  FIG. 5 , the condensation portion  22  of the heat pipe  150  comes into contact with the rear end of the heat radiation plate  120 , so that heat absorbed by the heat spreader  140  may be transferred rearward of the ultrasonic probe along the heat pipe  150  to be emitted through the heat radiation plate  120  to the outside. 
         [0055]      FIG. 6  is an exploded perspective view illustrating the ultrasonic probe in  FIG. 1 . As shown in  FIG. 6 , the ultrasonic probe includes the housing  100 , the heat radiation plates  120  provided inside the housing  100 , and the boards  130  provided inside the respective heat radiation plates  120 . In addition, a front housing  120  is provided with an assembly of the heat spreader  140  and the heat pipe  150 . 
         [0056]      FIGS. 8 to 11  are views illustrating a process of manufacturing the ultrasonic probe.  FIGS. 8 to 11  schematically show various configurations of the ultrasonic probe. 
         [0057]    Referring to (a) of  FIG. 8 , the heat spreader  140  is installed on the rear surface of the transducer  101  in order to absorb heat generated by the transducer  101 . 
         [0058]    The installed heat spreader  140  may be made of a metal such as aluminum having a high thermal conductivity, and may come into direct contact with the transducer  101  or come into indirect contact with the transducer  101  with a thermal medium interposed therebetween, thereby enabling heat generated by the transducer  101  to be absorbed. 
         [0059]    After the heat spreader  140  is installed, the heat radiation plates  120 , which are supplied with heat absorbed by the heat spreader  140  to emit the heat to the outside, are installed to the heat spreader  140  (see (b) of  FIG. 8 ). 
         [0060]    The heat radiation plates  120  may also be made of a metal having a high thermal conductivity. The heat radiation plates  120  may be coupled to the side surfaces of the heat spreader  140  using the fastening members, or may be installed by being inserted into the heat spreader  140 . 
         [0061]    The heat radiation plates  120  may be previously manufactured so as to have a shape similar to a shape of the housing  100 . 
         [0062]    After the heat radiation plates  120  are installed, the boards  130  are installed inside of the respective heat radiation plates  120  (see (c) of  FIG. 8 ). 
         [0063]    The boards  130  may be installed inside of the respective heat radiation plates  120  by using the fastening members. Each of the boards  130  receives a signal related to driving of the ultrasonic probe through the cable extension portion  111  of the rear housing  110  from the cable connected to the inside of the ultrasonic probe so as to output a signal to control driving of the transducer  101 . The board  130  includes the circuit board on which chips to control driving of the ultrasonic probe are mounted. The board  130  is electrically connected to the transducer  101  via the flexible printed circuit board or the like so as to output the signal to the transducer  101 . 
         [0064]    After the boards  130  are installed, the housing  100  is installed outside the heat radiation plates  120  (see (d) of  FIG. 8 ). 
         [0065]    The form of each heat radiation plate  120 , for example, the bent form, has a shape corresponding to the housing  100 . Thus, when the housing  100  is installed, the housing  100  may be pressed against the heat radiation plate  120 , with the consequence that a gap between the housing  100  and the heat radiation plate  120  is very small. Therefore, heat radiation efficiency through the heat radiation plate  120  is not deteriorated. The space between the housing  100  and the heat radiation plate  120  may be determined such that radiation efficiency of heat emitted from the heat radiation plate  120  through the housing  100  to the outside reaches a certain level or more, as determined by an experiment. 
         [0066]    Referring to (a) of  FIG. 9 , the heat spreader  140  is installed on the rear surface of the transducer  101  in order to absorb heat generated by the transducer  101 , and the heat pipe  150  is installed on the rear surface of the heat spreader  140 . 
         [0067]    The installed heat spreader  140  may be made of a metal having a high thermal conductivity, such as aluminum, and may come into direct contact with the transducer  101  or come into indirect contact with the transducer  101  with a thermal medium interposed therebetween, thereby enabling heat generated by the transducer  101  to be absorbed. 
         [0068]    The heat spreader  140  may be provided with the heat pipe  150  to transfer heat absorbed by the heat spreader  140  in a direction opposite to a direction in which ultrasonic waves are projected, namely, in a z-axis direction. 
         [0069]    The heat spreader  140  may be provided with an insertion groove into which the heat pipe  150  may be inserted, and the heat pipe  150  may be inserted into the insertion groove to be installed on the heat spreader  140 . In order to efficiently transfer heat from the heat spreader  140  to the heat pipe  150 , the insertion groove provided in the heat spreader  140  may have a depth which reaches a thermal contact surface between the heat spreader  140  and the transducer  101 . In other words, the heat pipe  150  may be inserted to such a degree as to reach the thermal contact surface between the heat spreader  140  and the transducer  101 . 
         [0070]    After the heat spreader  140  and the heat pipe  150  are installed, the heat radiation plates  120  to emit heat absorbed by the heat spreader  140  and heat transferred through the heat pipe  150  to the outside are installed on the heat spreader  140  (see (b) of  FIG. 9 ). 
         [0071]    The heat radiation plates  120  may be made of a metal having a high thermal conductivity. The heat radiation plates  120  may be coupled to the side surfaces of the heat spreader  140  through the fastening members, or may be installed by being inserted into the heat spreader  140 . In addition, the heat radiation plates  120  may be previously manufactured so as to have a shape similar to a shape of the housing  100 . As shown in  FIG. 9 , the rear ends of the heat radiation plates  120  are provided so as to come into thermal contact with the condensation portion  22  of the heat pipe  150 . Accordingly, the heat radiation plates  120  emit heat absorbed by the heat spreader  140  and heat transferred through the heat pipe  150  to the outside. 
         [0072]    After the heat radiation plates  120  are installed, the boards  130  are installed inside of the respective heat radiation plates  120  (see (c) of  FIG. 9 ). 
         [0073]    The boards  130  may be installed inside of the respective heat radiation plates  120  by the fastening members. Each of the boards  130  receives a signal related to driving of the ultrasonic probe through the cable extension portion  111  of the rear housing  110  from the cable connected to the inside of the ultrasonic probe so as to output a signal to control driving of the transducer  101 . The board  130  includes the circuit board on which chips to control driving of the ultrasonic probe are mounted. The board  130  is electrically connected to the transducer  101  via the flexible printed circuit board or the like so as to output the signal to the transducer  101 . 
         [0074]    After the boards  130  are installed, the housing  100  is installed outside the heat radiation plates  120  (see (d) of  FIG. 9 ). 
         [0075]    The form of each heat radiation plate  120 , for example, the bent form, has a shape corresponding to the housing  100 . Thus, when the housing  100  is installed, the housing  100  may be pressed against the heat radiation plate  120 , with the consequence that a gap between the housing  100  and the heat radiation plate  120  is very small. Therefore, heat radiation efficiency through the heat radiation plate  120  is not deteriorated. The space between the housing  100  and the heat radiation plate  120  may be determined such that radiation efficiency of heat emitted from the heat radiation plate  120  through the housing  100  to the outside reaches a certain level or more, as determined by an experiment. 
         [0076]    Referring to (a) of  FIG. 10 , the heat spreader  140  is installed on the rear surface of the transducer  101  in order to absorb heat generated by the transducer  101 . 
         [0077]    The installed heat spreader  140  may be made of a metal having a high thermal conductivity, such as aluminum, and may come into direct contact with the transducer  101  or come into indirect contact with the transducer  101  with a thermal medium interposed therebetween, thereby enabling heat generated by the transducer  101  to be absorbed. 
         [0078]    After the heat spreader  140  is installed, the heat radiation plates  120 , which are supplied with heat absorbed by the heat spreader  140  to emit the heat to the outside, are installed on the heat spreader  140  (see (b) of  FIG. 10 ). 
         [0079]    The heat radiation plates  120  may also be made of a metal having a high thermal conductivity. The heat radiation plates  120  may be coupled to the side surfaces of the heat spreader  140  by using the fastening members, or may be installed by being inserted into the heat spreader  140 . 
         [0080]    The heat radiation plates  120  may be previously manufactured so as to have a shape similar to a shape of the housing  100 . 
         [0081]    After the heat radiation plates  120  are installed, the boards  130  are installed inside of the respective heat radiation plates  120  (see (c) of  FIG. 10 ). 
         [0082]    The boards  130  may be installed inside of the respective heat radiation plates  120  by the fastening members. Each of the boards  130  receives a signal related to driving of the ultrasonic probe through the cable extension portion  111  of the rear housing  110  from the cable connected to the inside of the ultrasonic probe so as to output a signal to control driving of the transducer  101 . The board  130  includes the circuit board on which chips to control driving of the ultrasonic probe are mounted. The board  130  is electrically connected to the transducer  101  via the flexible printed circuit board or the like so as to output the signal to the transducer  101 . 
         [0083]    After the boards  130  are installed, heat radiation members  160 , which may, for example, made of graphite, are installed outside the respective heat radiation plates  120  (see (d) of  FIG. 10 ). 
         [0084]    The two heat radiation members  160  having a shape similar to that of each of the heat radiation plates  120  and the housing  100  are respectively installed outside the two heat radiation plates  120 , the housing  100  is installed outside the heat radiation members  160 , and the heat radiation members  160  made of graphite are installed in the respective spaces between the heat radiation plates  120  and the housing  100 . Graphite is a material having a thermal conductivity more than two times a thermal conductivity of aluminum. The heat radiation members  160  are filled in the spaces between the heat radiation plates  120  and the housing  100 , instead of filling the spaces with air, thereby enabling heat transfer and heat radiation to be more efficiently performed than when the heat radiation members  160  are not present. 
         [0085]    After the heat radiation members  160  made of graphite are installed, the housing  100  is installed outside the heat radiation members  160  (see (e) of  FIG. 10 ). 
         [0086]    The form of each heat radiation plate  120 , for example, the bent form, has a shape corresponding to the housing  100 . Thus, when the housing  100  is installed, the housing  100  may be pressed against the heat radiation plate  120 , with the consequence that a gap between the housing  100  and the heat radiation plate  120  is very small. Therefore, heat radiation efficiency through the heat radiation plate  120  is not deteriorated. The space between the housing  100  and the heat radiation plate  120  may be determined such that radiation efficiency of heat emitted from the heat radiation plate  120  through the housing  100  to the outside reaches a certain level or more, as determined by an experiment. In addition, the cable extension portion  111  provided in the rear end of the housing  100  is provided so as to come into thermal contact with the heat radiation members  160  which may be made of graphite. The cable extension portion  111  may be made of a material having a high thermal conductivity to emit heat transferred from the heat radiation members  160  to the outside. 
         [0087]    Referring to (a) of  FIG. 11 , the heat spreader  140  is installed on the rear surface of the transducer  101  in order to absorb heat generated by the transducer  101 , and the heat pipe  150  is installed on the rear surface of the heat spreader  140 . 
         [0088]    The installed heat spreader  140  may be made of a metal having a high thermal conductivity, such as aluminum, and may come into direct contact with the transducer  101  or come into indirect contact with the transducer  101  by interposing a thermal medium therebetween, thereby enabling heat generated by the transducer  101  to be absorbed. 
         [0089]    The heat spreader  140  may be provided with the heat pipe  150  to transfer heat absorbed by the heat spreader  140  in a direction opposite to a direction in which ultrasonic waves are projected, namely, in a z-axis direction. 
         [0090]    The heat spreader  140  may be provided with the insertion groove into which the heat pipe  150  may be inserted, and the heat pipe  150  may be inserted into the insertion groove to be installed on the heat spreader  140 . In order to efficiently transfer heat from the heat spreader  140  to the heat pipe  150 , the insertion groove provided in the heat spreader  140  may have a depth which reaches a thermal contact surface between the heat spreader  140  and the transducer  101 . In other words, the heat pipe  150  may be inserted to such a degree as to reach the thermal contact surface between the heat spreader  140  and the transducer  101 . 
         [0091]    After the heat spreader  140  and the heat pipe  150  are installed, the heat radiation plates  140  to emit heat absorbed by the heat spreader  140  and heat transferred through the heat pipe  150  to the outside are installed on the heat spreader  140  (see (b) of  FIG. 11 ). 
         [0092]    The heat radiation plates  120  may also be made of a metal having a high thermal conductivity. The heat radiation plates  120  may be coupled to the side surfaces of the heat spreader  140  by the fastening members, or may be installed by being inserted into the heat spreader  140 . 
         [0093]    The heat radiation plates  120  may be previously manufactured so as to have a shape similar to a shape of the housing  100 . 
         [0094]    After the heat radiation plates  120  are installed, the boards  130  are installed inside of the respective heat radiation plates  120  (see (c) of  FIG. 11 ). 
         [0095]    The boards  130  may be installed inside of the respective heat radiation plates  120  by the fastening members. Each of the boards  130  receives a signal related to driving of the ultrasonic probe through the cable extension portion  111  of the rear housing  110  from the cable connected to the inside of the ultrasonic probe so as to output a signal to control driving of the transducer  101 . The board  130  includes the circuit board on which chips to control driving of the ultrasonic probe are mounted. The board  130  is electrically connected to the transducer  101  via the flexible printed circuit board or the like so as to output the signal to the transducer  101 . 
         [0096]    After the boards  130  are installed, the heat radiation members  160  which may be made of graphite are installed outside the respective heat radiation plates  120  (see (d) of  FIG. 11 ). 
         [0097]    The two heat radiation members  160  having a shape similar to a shape of each of the heat radiation plates  120  and the housing  100  are respectively installed outside the two heat radiation plates  120 , the housing  100  is installed outside the heat radiation members  160 , and the heat radiation members  160  which may be made of graphite are thus installed in the respective spaces between the heat radiation plates  120  and the housing  100 . Graphite is a material having a thermal conductivity more than two times a thermal conductivity of aluminum. The heat radiation members  160  are filled, in the spaces between the heat radiation plates  120  and the housing  100 , instead of filling the spaces with air, thereby enabling heat transfer and heat radiation to be more efficiently performed than when the heat radiation members  160  are not present. 
         [0098]    After the heat radiation members  160  made of graphite are installed, the housing  100  is installed outside the heat radiation members  160  (see (e) of  FIG. 11 ). 
         [0099]    The form of each heat radiation plate  120 , for example, the bent form, has a shape corresponding to the housing  100 . Thus, when the housing  100  is installed, the housing  100  may be pressed against the heat radiation plate  120 , with the consequence that a gap between the housing  100  and the heat radiation plate  120  is very small. Therefore, heat radiation efficiency through the heat radiation plate  120  is not deteriorated. The space between the housing  100  and the heat radiation plate  120  may be determined such that radiation efficiency of heat emitted from the heat radiation plate  120  through the housing  100  to the outside reaches a certain level or more, as determined by an experiment. In addition, the cable extension portion  111  provided in the rear end of the housing  100  is provided so as to come into thermal contact with the heat radiation members  160  which may be made of graphite. The cable extension portion  111  may be made of a material having a high thermal conductivity to emit heat transferred from the heat radiation members  160  to the outside. 
         [0100]    As is apparent from the above description, the exemplary embodiments may enhance thermal stability of an ultrasonic probe by efficiently emitting heat generated by the ultrasonic probe to the outside. 
         [0101]    Although a few exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the exemplary embodiments, the scope of which is defined in the claims and their equivalents.