Abstract:
Disclosed herein is an angular velocity sensor including: a mass body part including a plurality of mass bodies; an internal frame supporting the mass body part; a flexible part for sensing connecting the mass body part to the internal frame so that the mass body part is rotatable and provided with a sensing unit; an external frame supporting the internal frame; and a flexible part for vibrating connecting the internal frame to the external frame so that the internal frame is rotatable and provided with a driving unit, wherein the flexible part for vibrating provided with the driving unit is disposed at an outer side of the internal frame in a displacement direction of the mass body part depending on rotation of the mass body part.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2013-0099331, filed on Aug. 21, 2013, entitled “Angular Velocity Sensor”, which is hereby incorporated by reference in its entirety into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to an angular velocity sensor. 
         [0004]    2. Description of the Related Art 
         [0005]    Recently, an angular velocity sensor has been used in various applications, for example, military such as an artificial satellite, a missile, an unmanned aircraft, or the like, vehicles such as an air bag, electronic stability control (ESC), a black box for a vehicle, or the like, hand shaking prevention of a camcorder, motion sensing of a mobile phone or a game machine, navigation, or the like. 
         [0006]    The angular velocity sensor generally adopts a configuration in which a mass body is adhered to an elastic substrate such as a membrane, or the like, in order to measure an angular velocity. Through the configuration, the angular velocity sensor may calculate the angular velocity by measuring Coriolis force applied to the mass body. 
         [0007]    In detail, a scheme of measuring the angular velocity using the angular velocity sensor is as follows. First, the angular velocity may be measured by Coriolis force “F=2mΩv”, where “F” represents the Coriolis force acting on the mass body, “m” represents the mass of the mass body, “Ω” represents the angular velocity to be measured, and “v” represents the motion velocity of the mass body. Among others, since the motion velocity v of the mass body and the mass m of the mass body are values known in advance, the angular velocity Ω may be obtained by detecting the Coriolis force (F) acting on the mass body. 
         [0008]    Meanwhile, the angular velocity sensor according to the prior art includes a piezoelectric material disposed on a membrane (a diaphragm) in order to drive a mass body or sense displacement of the mass body, as disclosed in the following Prior Art Document (Patent Document). In order to measure the angular velocity using the angular velocity sensor, it is preferable to allow a resonant frequency of a driving mode and a resonant frequency of a sensing mode to substantially coincide with each other. However, very large interference occurs between the driving mode and the sensing mode due to a fine manufacturing error caused by a shape, stress, a physical property, or the like. Therefore, since a noise signal significantly larger than an angular velocity signal is output, circuit amplification of the angular velocity signal is limited, such that sensitivity of the angular velocity sensor is deteriorated. 
       PRIOR ART DOCUMENT 
     Patent Document 
       [0000]    
       
         (Patent Document 1) US20110146404 A1 
       
     
       SUMMARY OF THE INVENTION 
       [0010]    The present invention has been made in an effort to provide a driving part integrated type angular velocity sensor capable of removing interference between a driving mode and a sensing mode and decreasing an effect due to a manufacturing error by driving a frame and a mass body by a single driving part to individually generate driving displacement and sensing displacement of the mass body and forming flexible parts so that the mass body is movable only in a specific direction. 
         [0011]    Further, the present invention has been made in an effort to provide an angular velocity sensor capable of improving sensitivity by maximizing a mass body part in a limited region due to an optimal structure. 
         [0012]    According to a preferred embodiment of the present invention, there is provided an angular velocity sensor including: a mass body part including a plurality of mass bodies; an internal frame supporting the mass body part; a flexible part for sensing connecting the mass body part to the internal frame so that the mass body part is rotatable and provided with a sensing unit; an external frame supporting the internal frame; and a flexible part for vibrating connecting the internal frame to the external frame so that the internal frame is rotatable and provided with a driving unit, wherein the flexible part for vibrating provided with the driving unit is disposed at an outer side of the internal frame in a displacement direction of the mass body part depending on rotation of the mass body part. 
         [0013]    A connection direction in which the flexible part for sensing provided with the sensing unit connects the mass body and the internal frame to each other may be in parallel with a connection direction in which the flexible part for vibrating provided with the driving unit connects the internal frame and the external frame to each other. 
         [0014]    The flexible part for sensing may include first and second flexible parts connecting the mass body part to the internal frame, respectively, wherein the first and second flexible parts may be disposed in a direction in which they are perpendicular to each other. 
         [0015]    The first flexible part may be a beam having a surface formed by one axis direction and the other axis direction and a thickness extended in a direction perpendicular to the surface. 
         [0016]    The first flexible part may be a beam having a predetermined thickness in a Z axis direction and a surface formed by X and Y axes and have a width W 1  in an X axis direction larger than a thickness T 1  in the Z axis direction. 
         [0017]    The second flexible part may be a hinge having a thickness in one axis direction and a surface formed in the other axis direction. 
         [0018]    The second flexible part may be a hinge having a predetermined thickness in a Y axis direction and a surface formed in X and Z axes and have a width W 2  in a Z axis direction larger than a thickness T 2  in the Y axis direction. 
         [0019]    One surfaces of the first and second flexible parts may be individually or selectively provided with the sensing unit sensing a displacement of the mass body. 
         [0020]    The flexible part for vibrating may include third and fourth flexible parts connecting the internal frame to the external frame, respectively, and a connection direction in which the third flexible part connects the internal frame to the external frame and a connection direction in which the fourth flexible part connects the internal frame to the external frame may be in parallel with each other. 
         [0021]    The third flexible part may be a beam having a surface formed by one axis direction and the other axis direction and a thickness extended in a direction perpendicular to the surface. 
         [0022]    The third flexible part may be a beam having a predetermined thickness in a Z axis direction and a surface formed by X and Y axes and have a width W 3  in an X axis direction larger than a thickness T 3  in the Z axis direction. 
         [0023]    The fourth flexible part may be a hinge having a thickness in one axis direction and a surface formed in the other axis direction. 
         [0024]    The fourth flexible part may be a hinge having a predetermined thickness in an X axis direction and a surface formed in Y and Z axes and have a width W 4  in a Z axis direction larger than a thickness T 4  in the X axis direction. 
         [0025]    The fourth flexible part may be connected to a central portion of the internal frame, and the internal frame may be rotated so that a symmetrical displacement is generated based on the fourth flexible part. 
         [0026]    One surfaces of the third and fourth flexible parts may be individually or selectively provided with the driving unit driving the internal frame. 
         [0027]    The mass body part may include first and second mass bodies disposed to be symmetrical to each other. 
         [0028]    The first and second mass bodies supported by the internal frame may be disposed to be symmetrical to each other based on the fourth flexible part connected to the internal frame. 
         [0029]    The internal frame may include protrusion coupling parts protruding toward the external frame so that the flexible parts for sensing provided with the sensing unit are connected thereto. 
         [0030]    The protrusion coupling parts may be formed at both end portions of the internal frame so as to be extended in an X axis, and flexible parts for sensing may be coupled to the protrusion coupling parts in a Y axis direction. 
         [0031]    According to another preferred embodiment of the present invention, there is provided an angular velocity sensor including: a mass body part including a plurality of mass bodies; an internal frame supporting the mass body part; a flexible part for sensing connecting the mass body part to the internal frame so that the mass body part is rotatable and provided with a sensing unit; an external frame supporting the internal frame; and a flexible part for vibrating connecting the internal frame to the external frame so that the internal frame is rotatable and provided with a driving unit, wherein the flexible part for sensing provided with the sensing unit is disposed at an outer side in a displacement direction of the mass body part depending on rotation of the mass body part. 
         [0032]    A connection direction in which the flexible part for sensing provided with the sensing unit connects the mass body and the internal frame to each other may be in parallel with a connection direction in which the flexible part for vibrating provided with the driving unit connects the internal frame and the external frame to each other. 
         [0033]    The internal frame may include protrusion coupling parts protruding toward the external frame so that the flexible parts for sensing provided with the sensing unit are connected thereto, the external frame may include coupling protrusion parts formed so as to be in parallel with the protrusion coupling parts of the internal frame, and one end of the flexible part for vibrating provided with the driving unit may be connected to the protrusion coupling part and the other end thereof may be connected to the coupling protrusion part. 
         [0034]    The flexible part for sensing may include first and second flexible parts connecting the mass body part to the internal frame, respectively, and a connection direction in which the first flexible part connects the internal frame to the mass body part may be in parallel with a connection direction in which the second flexible part connects the internal frame to the mass body part. 
         [0035]    Each of the first and second flexible parts connects the mass body part to the internal frame in an X axis direction, and the mass body part may have the first flexible parts connected to both end portions thereof, respectively, and the second flexible parts connected to central portions thereof, respectively, in a Y axis direction. 
         [0036]    The flexible part for vibrating may include third and fourth flexible parts connecting the internal frame to the external frame, respectively, and a connection direction in which the third flexible part connects the internal frame to the external frame and a connection direction in which the fourth flexible part connects the internal frame to the external frame may be perpendicular to each other. 
         [0037]    According to still another preferred embodiment of the present invention, there is provided an angular velocity sensor including: a mass body part including a plurality of mass bodies; an internal frame supporting the mass body part; a flexible part for sensing connecting the mass body part to the internal frame so that the mass body part is rotatable and provided with a sensing unit; an external frame supporting the internal frame; and a flexible part for vibrating connecting the internal frame to the external frame so that the internal frame is rotatable and provided with a driving unit, wherein the flexible part for vibrating provided with the driving unit is disposed at an outer side in a displacement direction of the mass body part depending on rotation of the mass body part, and the flexible part for sensing provided with the sensing unit is disposed at the outer side in the displacement direction of the mass body part depending on the rotation of the mass body part. 
         [0038]    A connection direction in which the flexible part for sensing provided with the sensing unit connects the mass body part and the internal frame to each other may be perpendicular to a connection direction in which the flexible part for vibrating provided with the driving unit connects the internal frame and the external frame to each other. 
         [0039]    The flexible part for sensing may include first and second flexible parts connecting the mass body part to the internal frame, respectively, and a connection direction in which the first flexible part connects the internal frame to the mass body part may be in parallel with a connection direction in which the second flexible part connects the internal frame to the mass body part. 
         [0040]    Each of the first and second flexible parts may connect the mass body part to the internal frame in an X axis direction, and the mass body part may have the first flexible parts connected to both end portions thereof, respectively, and the second flexible parts connected to central portions thereof, respectively, in a Y axis direction. 
         [0041]    The flexible part for vibrating may include third and fourth flexible parts connecting the internal frame to the external frame, respectively, and a connection direction in which the third flexible part connects the internal frame to the external frame and a connection direction in which the fourth flexible part connects the internal frame to the external frame may be in parallel with each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0042]    The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0043]      FIG. 1  is a perspective view schematically showing an angular velocity sensor according to a first preferred embodiment of the present invention; 
           [0044]      FIG. 2  is a plan view of the angular velocity sensor shown in  FIG. 1 ; 
           [0045]      FIG. 3  is a schematic cross-sectional view of the angular velocity sensor taken along the line A-A of  FIG. 2 ; 
           [0046]      FIG. 4  is a schematic cross-sectional view of the angular velocity sensor taken along the line B-B of  FIG. 2 ; 
           [0047]      FIG. 5  is a schematic cross-sectional view of the angular velocity sensor taken along the line C-C of  FIG. 2 ; 
           [0048]      FIG. 6  is a plan view showing movable directions of a mass body part and an internal frame in the angular velocity sensor shown in  FIG. 2 ; 
           [0049]      FIGS. 7A and 7B  are cross-sectional views showing a process in which a mass body part shown in  FIG. 4  is rotated with respect to an internal frame; 
           [0050]      FIGS. 8A and 8B  are cross-sectional views showing a process in which an internal frame shown in  FIG. 3  is rotated based on an external frame; 
           [0051]      FIG. 9  is a perspective view schematically showing an angular velocity sensor according to a second preferred embodiment of the present invention; 
           [0052]      FIG. 10  is a schematic plan view of the angular velocity sensor shown in  FIG. 9 ; 
           [0053]      FIG. 11  is a schematic cross-sectional view of the angular velocity sensor taken along the line A-A of  FIG. 9 ; 
           [0054]      FIG. 12  is a schematic cross-sectional view of the angular velocity sensor taken along the line B-B of  FIG. 9 ; 
           [0055]      FIG. 13  is a schematic cross-sectional view of the angular velocity sensor taken along the line C-C of  FIG. 9 ; and 
           [0056]      FIG. 14  is a plan view schematically showing an angular velocity sensor according to a third preferred embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0057]    The objects, features and advantages of the present invention will be more clearly understood from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant descriptions thereof are omitted. Further, in the following description, the terms “first”, “second”, “one side”, “the other side” and the like are used to differentiate a certain component from other components, but the configuration of such components should not be construed to be limited by the terms. Further, in the description of the present invention, when it is determined that the detailed description of the related art would obscure the gist of the present invention, the description thereof will be omitted. 
         [0058]    Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. 
         [0059]      FIG. 1  is a perspective view schematically showing an angular velocity sensor according to a first preferred embodiment of the present invention; and  FIG. 2  is a plan view of the angular velocity sensor shown in  FIG. 1 . 
         [0060]    As shown in  FIGS. 1 and 2 , the angular velocity sensor  100  is configured to include a mass body part  110 , an internal frame  120 , an external frame  130 , first flexible parts  140 , second flexible parts  150 , third flexible parts  160 , and fourth flexible parts  170 . 
         [0061]    In addition, the first and second flexible parts  140  and  150 , which are flexible parts sensing, are individually or selectively provided with a sensing unit  180 , and the third and fourth flexible parts  160  and  170 , which are flexible parts for vibrating, are individually or selectively provided with a driving unit  190 . 
         [0062]    Further, the third flexible part  160 , which is the flexible part for vibrating provided with the driving unit  190  is disposed at an outer side of the internal frame  120  with respect to rotation of the mass body part  110 . That is, a region P shown in an enlarged view of  FIG. 2  is a region corresponding to displacement directions of the third flexible part  160  and the first flexible part  140  depending on the rotation of the mass body part  110 . 
         [0063]    As described above, since the third flexible part  160  is disposed at the outer side of the internal frame  120  with respect to the rotation of the mass body part  110 , the third flexible part  160  is significantly deformed in the displacement direction (a Y axis direction), thereby making it possible to significantly rotate the internal frame  120 , and since a maximum length Lw1 of the mass body part  110  from the center of rotation is secured, the mass body  110  may secure a large mass, thereby making it possible to improve sensing sensibility. 
         [0064]    In addition, a connection direction in which the flexible part for sensing provided with the sensing unit  180  connects the mass body part and the internal frame to each other may be in parallel with a connection direction in which the flexible part for vibrating provided with the driving unit  190  connects the internal frame and the external frame to each other. 
         [0065]    That is, the first flexible part  140 , which is the flexible part for sensing provided with the sensing unit  180  connects the mass body part  110  and the internal frame  120  to each other in a C1 direction corresponding to the Y axis direction and the third flexible part  160  provided with the driving unit  190  connects the internal frame  120  and the external frame  130  to each other in a C2 direction corresponding to the Y axis direction, such that the C1 direction corresponding to the connection direction of the first flexible part  140  and the C2 direction corresponding to the connection direction of the third flexible part  160  are in parallel with each other. 
         [0066]    Next, the mass body  110 , which is displaced by Coriolis force, includes a first mass body  110   a  and a second mass body  110   b.    
         [0067]    In addition, the first and second mass bodies  110   a  and  110   b  may have the same size and be disposed to be symmetrical to each other. 
         [0068]    Further, the first and second mass bodies  110   a  and  110   b  are connected to the internal frame  120  by the first and second flexible parts  140  and  150 . 
         [0069]    In addition, the first and second mass bodies  110   a  and  110   b  are displaced based on the internal frame  120  by bending of the first flexible part  140  and twisting of the second flexible part  150  when Coriolis force acts thereon. Here, the first and second mass bodies  110   a  and  110   b  are rotated based on an X axis with respect to the internal frame  120 . A detailed content associated with this will be described below. 
         [0070]    Meanwhile, although the case in which the first and second mass bodies  110   a  and  110   b  have a generally square pillar shape is shown, the first and second mass bodies  110   a  and  110   b  are not limited to having the above-mentioned shape, but may have all shapes known in the art. 
         [0071]    In addition, the first and second mass bodies  110   a  and  110   b  positioned in the internal frame  120  are disposed to be symmetrical to each other based on the fourth flexible part  170  connected to the internal frame  120 . 
         [0072]    Further, the internal frame  120  supports the mass body part  110 . More specifically, the internal frame  120  may have the first and second mass bodies  110   a  and  110   b  positioned therein and be connected to the mass body part  110  by the first and second flexible parts  140  and  150 . That is, the internal frame  120  allows a space in which the mass body part  110  may be displaced to be secured and becomes a basis when the mass body part  110  is displaced. In addition, the internal frame  120  may also cover only a portion of the mass body part  110 . 
         [0073]    Further, the internal frame  120  may be divided into two space parts  120   a  and  120   b  so that the first and second mass bodies  110   a  and  110   b  are positioned therein. In addition, the internal frame  120  may have a square pillar shape in which it has a square pillar shaped cavity formed at the center thereof, but is not limited thereto. 
         [0074]    Further, the internal frame  120  may include protrusion coupling parts  121  protruding toward the external frame so that the third flexible part  160 , which is the flexible part for vibrating, is connected thereto. 
         [0075]    In addition, the protrusion coupling parts  121  protrude so that the internal frame  120  and the external frame  130  are connected to each other in the Y axis direction by the third flexible part  160  and are formed at both end portions of the internal frame  120  in the X axis direction so as to be extended in the X axis direction. Therefore, one end of the third flexible part  160  is coupled to the protrusion coupling part  121  of the internal frame and the other end thereof is coupled to the external frame  130 . That is, since the internal frame  120  should be rotated based on the fourth flexible part  170 , the protrusion coupling part  121  is not connected to the external frame  130 . 
         [0076]    Next, the external frame  130  supports the internal frame  120 . More specifically, the external frame  130  is provided at the outer side of the internal frame  120  so as to be spaced apart from the internal frame  120  and is connected to the internal frame  120  by the third and fourth flexible parts  160  and  170 . Therefore, the internal frame  120  and the mass body part  110  connected to the internal frame  120  are supported by the external frame  130  in a floated state so as to be displaceable. In addition, the external frame  130  may also cover only a portion of the internal frame  120 . 
         [0077]      FIG. 3  is a schematic cross-sectional view of the angular velocity sensor taken along the line A-A of  FIG. 2 ;  FIG. 4  is a schematic cross-sectional view of the angular velocity sensor taken along the line B-B of  FIG. 2 ; and  FIG. 5  is a schematic cross-sectional view of the angular velocity sensor taken along the line C-C of  FIG. 2 . 
         [0078]    Hereinafter, structural features, shapes, and organic couplings of the respective components of the angular velocity sensor  100  according to the first preferred embodiment of the present invention will be described in detail with reference to  FIGS. 1 to 5 . 
         [0079]    First, both end portions of the first and second mass bodies  110   a  and  110   b  of the mass body part  110  in the Y axis direction are connected to the internal frame  120  by the first flexible parts  140 , respectively, and both end portions of the first and second mass bodies  110   a  and  110   b  of the mass body part  110  in the X axis direction are connected to the internal frame  120  by the second flexible parts  150 , respectively. Here, the first and second mass bodies  110   a  and  110   b  have the second flexible parts  150  connected thereto at central portions thereof in the Y axis direction. Therefore, the first and second mass bodies  110   a  and  110   b  have the second flexible parts connected thereto so as to correspond to the centers of gravity thereof, respectively, and may be symmetrically moved by the second flexible parts, respectively, in the case in which they are rotated based on the second flexible parts, respectively. 
         [0080]    In addition, the first flexible part  140  is a beam having a predetermined thickness in a Z axis direction and having a surface formed by X and Y axes. That is, the first flexible part has a width W 1  in the X axis direction larger than a thickness T 1  in the Z axis direction. 
         [0081]    Further, in the Y axis direction, one end of the first flexible part  140  is connected to the mass body part  110  and the other end thereof is connected to the internal frame  120 . To this end, the first flexible part  140  is extended in the Y axis direction. 
         [0082]    In addition, the first flexible part  140  may be provided with the sensing unit  180 . That is, when viewed based on an XY plane, the first flexible part  140  is relatively wider than the second flexible part  150 . Therefore, the first flexible part  140  may be provided with the sensing unit  180  sensing displacements of the first and second mass bodies  110   a  and  110   b.    
         [0083]    In addition, the sensing unit  180  may be formed so as to use a piezoelectric scheme, a piezoresistive scheme, a capacitive scheme, an optical scheme, or the like, but is not particularly limited thereto. 
         [0084]    Further, the second flexible part  150  is a hinge having a predetermined thickness in the Y axis direction and having a surface formed by the X and Y axes. That is, the second flexible part  150  may have a width W 2  in the Z axis direction larger than a thickness T 2  in the Y axis direction. 
         [0085]    In addition, the first and second flexible parts  140  and  150  are disposed in a direction in which they are perpendicular to each other. That is, the first flexible part  140  is coupled to the mass body part  110  and the internal frame  120  in the Y axis direction, and the second flexible part  150  is coupled to the mass body part  110  and the internal frame  120  in the X axis direction. 
         [0086]    As described above, since the second flexible part  150  has the width W 2  in the Z axis direction larger than the thickness T 2  in the Y axis direction, the first and second mass bodies  110   a  and  110   b  are limited from being rotated based on the Y axis or translated in the Z axis direction, but may be relatively freely rotated based on the X axis. That is, the first and second mass bodies  110   a  and  110   b  are positioned in the internal frame  120  to thereby be rotated based on the X axis direction, and the second flexible part  150  serves as a hinge to this end. 
         [0087]    In addition, the third flexible part  160  is a beam having a predetermined thickness in the Z axis direction and having a surface formed by the X and Y axes. That is, the third flexible part  160  has a width W 3  in the X axis direction larger than a thickness T 3  in the Z axis direction. Further, in the Y axis direction, one end of the third flexible part  160  is connected to the internal frame and the other end thereof is connected to the external frame. To this end, the third flexible part  160  is extended in the Y axis direction. 
         [0088]    Therefore, the third flexible part  160  and the first flexible part  140  are extended in the Y axis direction and are disposed in parallel with each other. 
         [0089]    Further, the fourth flexible part  170  is a hinge having a predetermined thickness in the X axis direction and having a surface formed by the Y and Z axes. That is, the fourth flexible part  170  may have a width W 4  in the Z axis direction larger than a thickness T 4  in the X axis direction. Therefore, the internal frame  120  is limited from being rotated based on the X axis or translated in the Z axis direction, but may be relatively freely rotated based on the Y axis. That is, the internal frame  120  is fixed to the external frame  130  to thereby be rotated based on the Y axis direction, and the fourth flexible part  170  serves as a hinge to this end. 
         [0090]    In addition, the fourth flexible part  170  is coupled to a central portion between two space parts  120   a  and  120   b  of the internal frame. Further, in order to provide larger flexibility, a coupling groove part  122  is formed in the internal frame, and the fourth flexible part  170  may be inserted into and coupled to the coupling groove part  122 . 
         [0091]    That is, the fourth flexible part  170  is connected to the coupling groove part  122  formed at a central portion of the internal frame  120 , and the internal frame  120  is rotated so that a symmetrical displacement is generated based on the fourth flexible part  170 . 
         [0092]    In addition, the third and fourth flexible parts  160  and  170  are disposed so that directions in which they are extended, that is, directions in which they connect the internal frame  120  to the external frame  130  are in parallel with each other. 
         [0093]    That is, the third flexible part  160  is coupled to the internal frame  120  and the external frame  130  in the Y axis direction, and the fourth flexible part  170  is coupled to the internal frame  120  and the external frame  130  in the Y axis direction. 
         [0094]    In addition, as described above, one end of the third flexible part  160  is coupled to the protrusion coupling part  121  of the internal frame and the other end thereof is coupled to the external frame  130 . 
         [0095]    Therefore, the internal frame  120  may be displaced in a state in which it is supported to the external frame  130  by the third and fourth flexible parts  160  and  170 . 
         [0096]    In addition, the third and fourth flexible parts  160  and  170  may be selectively provided with the driving unit  190 . Here, the driving unit  190 , which is to drive the internal frame  120  and the mass body part  110 , may use a piezoelectric scheme, a capacitive scheme, or the like. In addition, when viewed based on the XY plane, the third flexible part  160  is relatively wider than the fourth flexible part  170 . Therefore, the third flexible part  160  may be provided with the driving unit  190  driving the internal frame  120 . 
         [0097]    Here, the driving unit  190  may drive the internal frame  120  so as to be rotated based on the Y axis. Here, the driving unit  190  may use a piezoelectric scheme, a capacitive scheme, or the like, but is not particularly limited thereto. 
         [0098]    In addition, the first to fourth flexible parts  140  to  170  are disposed as described above, such that the connection direction C1 in which the first flexible part  140  connects the mass body part  110  and the internal frame  120  to each other is in parallel with the connection direction C2 in which the third flexible part connects the internal frame  120  and the external frame  130  to each other. 
         [0099]    Further, the second and fourth flexible parts  150  and  170  are disposed in a direction in which they are perpendicular to each other. 
         [0100]    Further, the second and fourth flexible parts  150  and  170  of the angular velocity sensor according to the preferred embodiment of the present invention may have all possible shapes such as a hinge shape having a rectangular cross section, a torsion bar shape having a circular cross section, or the like. 
         [0101]    Through the configuration as described above, in the angular velocity sensor according to the first preferred embodiment of the present invention, the third flexible part  160  is disposed at the outer side of the internal frame in the displacement direction of the mass body part depending on the rotation of the mass body part, such that a size of the internal frame positioned in the external frame may be maximized in the Y axis direction. Therefore, the mass body part may be designed at a maximum size in the Y axis direction when it is formed. 
         [0102]    That is, since the mass body part is rotated based on the X axis and is rotation-displaced in the Y axis direction, a size of the mass body part in the Y axis direction as large as possible should be secured in order to generate a maximum displacement. In this case, sensing sensitivity is improved. Therefore, the angular velocity sensor according to the first preferred embodiment of the present invention may improve the sensing sensitivity through optimal structures and organic couplings of the third flexible part  160 , the internal frame  120 , and the external frame  130  described above. 
         [0103]    Hereinafter, movable directions and driving examples of the mass body and the internal frame in the angular velocity sensor according to the first preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings. 
         [0104]      FIG. 6  is a plan view showing movable directions of a mass body part and an internal frame in the angular velocity sensor shown in  FIG. 2 . 
         [0105]    First, relationships among the width W 2  of the second flexible part  150  in the Z axis direction, a length L 1  thereof in the X axis direction, the thickness T 2  thereof in the Y axis direction, and rigidities thereof in each direction may be represented by the following Equations. 
         [0106]    (1) The rigidity of the second flexible part  150  at the time of the rotation based on the Y axis or the rigidity thereof at the time of the translation in the Z axis direction ∝W 2   3 ×T 2 /L 1   3    
         [0107]    (2) The rigidity of the second flexible part  150  at the time of the rotation based on the X axis ∝T 2   3 W 2 /L 1    
         [0108]    According to the above two Equations, the value of (the rigidity of the second flexible part  150  at the time of the rotation based on the Y axis or the rigidity of the second flexible part  150  at the time of the translation in the Z axis direction)/(the rigidity of the second flexible part  150  at the time of the rotation based on the X axis) is in proportion to (W 2 /(T 2 L 1 )) 2 . 
         [0109]    However, since the second flexible part  150  according to the present embodiment has the width W2 in the Z axis direction larger than the thickness T 2  in the Y axis direction, (W 2 /(T 2 L 1 )) 2  is large, such that the value of (the rigidity of the second flexible part  150  at the time of the rotation based on the Y axis or the rigidity of the second flexible part  150  at the time of the translation in the Z axis direction)/(the rigidity of the second flexible part  150  at the time of the rotation based on the X axis) increases. Due to these characteristics of the second flexible part  150 , the first and second mass bodies  110   a  and  110   b  are freely rotated based on the X axis, but are limited from being rotated based on the Y axis or translated in the Z axis direction, with respect to the internal frame  120 . 
         [0110]    Meanwhile, the first flexible part  140  has relatively very high rigidity in the length direction (the Y axis direction), thereby making it possible to limit the first and second mass bodies  110   a  and  110   b  from being rotated based on the Z axis or translated in the Y axis direction, with respect to the internal frame  120 . 
         [0111]    In addition, the second flexible part  150  has relatively very high rigidity in the length direction (the X axis direction), thereby making it possible to limit the first and second mass bodies  110   a  and  110   b  from being translated in the X axis direction, with respect to the internal frame  120 . 
         [0112]    As a result, due to the characteristics of the first and second flexible parts  140  and  150  described above, the first and second mass bodies  110   a  and  110   b  may be rotated based on the X axis, but are limited from being rotated based on the Y or Z axis or translated in the Z, Y, or X axis direction, with respect to the internal frame  120 . That is, the movable directions of the first and second mass bodies  110   a  and  110   b  may be represented by the following Table 1. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Movable directions of first and second  
                 Whether or not  
               
               
                   
                 mass bodies (based on internal frame) 
                 movement is possible 
               
               
                   
                   
               
             
             
               
                   
                 Rotation based on X axis 
                 Possible 
               
               
                   
                 Rotation based on Y axis 
                 Limited 
               
               
                   
                 Rotation based on Z axis 
                 Limited 
               
               
                   
                 Translation in X axis direction 
                 Limited 
               
               
                   
                 Translation in Y axis direction 
                 Limited 
               
               
                   
                 Translation in Z axis direction 
                 Limited 
               
               
                   
                   
               
             
          
         
       
     
         [0113]    As described above, since the first and second mass bodies  110   a  and  110   b  may be rotated based on the X axis, that is, the second flexible part  150 , but are limited from being moved in the remaining directions, with respect to the internal frame  120 , the first and second mass bodies  110   a  and  110   b  may be allowed to be displaced only with respect to force in a desired direction (the rotation based on the X axis). 
         [0114]    Next, since the fourth flexible part  170  has a width W 4  in the Z axis direction larger than a thickness T 4  in the X axis direction, the internal frame  120  is limited from being rotated based on the X axis or translated in the Y axis direction, but is relatively freely rotated based on the Y axis. 
         [0115]    More specifically, in the case in which rigidity of the fourth flexible part  170  at the time of rotation based on the X axis is larger than rigidity of the fourth flexible part  170  at the time of rotation based on the Y axis, the internal frame  120  may be freely rotated based on the Y axis, but is limited from being rotated based on the X axis. Similarly, in the case in which rigidity of the fourth flexible part  170  at the time of translation in the Z axis direction is larger than the rigidity of the fourth flexible part  170  at the time of the rotation based on the Y axis, the internal frame  120  may be freely rotated based on the Y axis, but is limited from being translated in the Z axis direction. 
         [0116]    Therefore, as a value of (the rigidity of the fourth flexible part  170  at the time of the rotation based on the X axis or the rigidity of the fourth flexible part  170  at the time of the translation in the Z axis direction)/(the rigidity of the fourth flexible part  170  at the time of the rotation based on the Y axis) increases, the internal frame  120  is freely rotated based on the Y axis, but is limited from being rotated based on the X axis or translated in the Z axis direction, with respect to the external frame  130 . 
         [0117]    First, relationships among the width W 4  of the fourth flexible part  170  in the Z axis direction, a length L 2  thereof in the Y axis direction, the thickness T 4  thereof in the X axis direction, and rigidities thereof in each direction may be represented by the following Equations. 
         [0118]    (1) The rigidity of the fourth flexible part  170  at the time of the rotation based on the X axis or the rigidity thereof at the time of the translation in the Z axis direction ∝T 4 ×W 4   3 /L 2   3    
         [0119]    (2) The rigidity of the fourth flexible part  170  at the time of the rotation based on the Y axis ∝T 4   3 ×W 4 /L 2    
         [0120]    According to the above two Equations, the value of (the rigidity of the fourth flexible part  170  at the time of the rotation based on the X axis or the rigidity of the fourth flexible part  170  at the time is of the translation in the Z axis direction)/(the rigidity of the fourth flexible part  170  at the time of the rotation based on the Y axis) is in proportion to (W 4 /(T 4 L 2 )) 2 . 
         [0121]    However, since the fourth flexible part  170  has the width W 4  in the Z axis direction larger than the thickness T 4  in the X axis direction, (W 4 /(T 4 L 2 )) 2  is large, such that the value of (the rigidity of the fourth flexible part  170  at the time of the rotation based on the X axis or the rigidity of the fourth flexible part  170  at the time of the translation in the Z axis direction)/(the rigidity of the fourth flexible part  170  at the time of the rotation based on the Y axis) increases. Due to these characteristics of the fourth flexible part  170 , the internal frame  120  is rotated based on the Y axis, but is limited from being rotated based on the X axis or translated in the Z axis direction, with respect to the external frame  130 . 
         [0122]    Meanwhile, the third flexible part  160  has relatively very high rigidity in the length direction (the Y axis direction), thereby making it possible to limit the internal frame  120  from being rotated based on the Z axis or translated in the Z axis direction, with respect to the external frame  130 . In addition, the fourth flexible part  170  has relatively very high rigidity in the length direction (the Y axis direction), thereby making it possible to limit the internal frame  120  from being translated in the Y axis direction, with respect to the external frame  130  (See  FIG. 8 ). 
         [0123]    As a result, due to the characteristics of the third and fourth flexible parts  160  and  170  described above, the internal frame  120  may be rotated based on the Y axis, but are limited from being rotated based on the X or Z axis or translated in the Z, Y, or X axis direction, with respect to the external frame  130 . That is, the movable directions of the internal frame  120  may be represented by the following Table 2. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Movable direction of internal  
                 Whether or not  
               
               
                   
                 frame (based on external frame) 
                 movement is possible 
               
               
                   
                   
               
             
             
               
                   
                 Rotation based on X axis 
                 Limited 
               
               
                   
                 Rotation based on Y axis 
                 Possible 
               
               
                   
                 Rotation based on Z axis 
                 Limited 
               
               
                   
                 Translation in X axis direction 
                 Limited 
               
               
                   
                 Translation in Y axis direction 
                 Limited 
               
               
                   
                 Translation in Z axis direction 
                 Limited 
               
               
                   
                   
               
             
          
         
       
     
         [0124]    As described above, since the internal frame  120  may be rotated based on the Y axis, but is limited from being moved in the remaining directions, with respect to the external frame  130 , the internal frame  120  may be allowed to be displaced only with respect to force in a desired direction (the rotation based on the Y axis). 
         [0125]      FIGS. 7A and 7B  are cross-sectional views showing a process in which a mass body part shown in  FIG. 4  is rotated with respect to an internal frame. 
         [0126]    As shown in  FIGS. 7A and 7B , since the first mass body  110   a  of the mass body part  110  is rotated based on the X axis as a rotation axis R with respect to the internal frame  120 , that is, since the first mass body  110   a  is rotated based on an axis on which the second flexible part  150  is coupled thereto with respect to the internal frame, bending stress in which compression stress and tension stress are combined with each other is generated in the first flexible part  140 , and twisting stress is generated based on the X axis in the second flexible part  150 . 
         [0127]    In this case, in order to generate a torque in the first mass body  110   a , the second flexible part  150  may be disposed over the center C of gravity of the first mass body  110   a  based on the Z axis direction. 
         [0128]    Meanwhile, as shown in  FIG. 2 , the second flexible part  150  is disposed at a position corresponding to the center C of gravity of the first mass body  110   a  based on the X axis direction so that the first mass body  110   a  is rotated depending on a symmetrical displacement based on the X axis. 
         [0129]    In addition, bending stress of the first flexible part  140  depending on rotation movement of the first mass body  110   a  is detected by the sensing unit  180 . 
         [0130]      FIGS. 8A and 8B  are cross-sectional views showing a process in which an internal frame shown in  FIG. 3  is rotated based on an external frame. As shown in  FIGS. 8A and 8B , since the internal frame  120  is rotated based on the Y axis with respect to the external frame  130 , that is, since the internal frame  120  is rotated based on the fourth flexible part  170  hinge-coupling the internal frame  120  to the external frame  130 , bending stress in which compression stress and tension stress are combined with each other is generated in the third flexible part  160 , and twisting stress is generated based on the Y axis in the fourth flexible part  170 . 
         [0131]    The angular velocity sensor according to the first preferred embodiment of the present invention is configured as described above. Hereinafter, an angular velocity measuring method by the angular velocity sensor  100  will be described in detail. 
         [0132]    First, the internal frame  120  is rotated based on the Y axis with respect to the external frame  130  using the driving unit  190 . Here, the first and second mass bodies  110   a  and  110   b  vibrate while being rotated together with the internal frame  120  based on the Y axis, and a displacement is generated in the first and second mass bodies  110   a  and  110   b  due to the vibrations. 
         [0133]    More specifically, a displacement (+X, −Z) in a +X axis direction and a −Z axis direction is generated in the first mass body  110   a  and at the same time, a displacement (+X, +Z) in the +X axis direction and a +Z axis direction is generated in the second mass body  110   b . Then, a displacement (−X, +Z) in a −X axis direction and the +Z axis direction is generated in the first mass body  110   a  and at the same time, a displacement (−X, −Z) in the −X axis direction and the −Z axis direction is generated in the second mass body  110   b . Here, when an angular velocity rotated based on the X or Z axis is applied to the first and second mass bodies  110   a  and  110   b , Coriolis force is generated. 
         [0134]    The first and second mass bodies  110   a  and  110   b  are displaced while being rotated based on the X axis with respected to the internal frame  120  by the Coriolis force, and the sensing unit  180  senses the displacements of the first and second mass bodies  110   a  and  110   b.    
         [0135]    More specifically, when the angular velocity rotated based on the X axis is applied to the first and second mass bodies  110   a  and  110   b , the Coriolis force is generated in a −Y axis and then generated in a +Y axis in the first mass body  110   a , and the Coriolis force is generated in the +Y axis and then is generated in the −Y axis in the second mass body  110   b.    
         [0136]    Therefore, the first and second mass bodies  110   a  and  110   b  are rotated based on the X axis in directions opposite to each other, the sensing unit  180  may sense each of the displacements of the first and second mass bodies  110   a  and  110   b  to calculate the Coriolis force, and an angular velocity rotated based on the X axis may be measured through the Coriolis force. 
         [0137]    Meanwhile, when signals each generated in the first flexible part  140  and the sensing unit  180  connected to both end portions of the first mass body  110   a  are defined as SY1 and SY2 and signals each generated in the first flexible part  140  and the sensing unit  180  connected to both end portions of the second mass body  110   b  are defined as SY3 and SY4, an angular velocity rotated based on the X axis may be calculated from (SY1−SY2)−(SY3−SY4). As described above, since the signals are differentially output between the first and second mass bodies  110   a  and  110   b  rotated in the directions opposite to each other, acceleration noise may be offset. 
         [0138]    In addition, when the angular velocity rotated based on the Z axis is applied to the first and second mass bodies  110   a  and  110   b , the Coriolis force is generated in the −Y axis and then generated in the +Y axis in the first mass body  110   a , and the Coriolis force is generated in the +Y axis and then is generated in the −Y axis in the second mass body  110   b . Therefore, the first and second mass bodies  110   a  and  110   b  are rotated based on the X axis in the same direction as each other, the sensing unit  180  may sense the displacements of the first and second mass bodies  110   a  and  110   b  to calculate the Coriolis force, and an angular velocity rotated based on the Z axis may be measured through the Coriolis force. 
         [0139]    Here, when signals each generated in the first flexible part  140  and the sensing unit  180  connected to both end portions of the first mass body  110   a  are defined as SY1 and SY2 and signals each generated in the first flexible part  140  and the sensing unit  180  connected to both end portions of the second mass body  110   b  are defined as SY3 and SY4, an angular velocity rotated based on the Z axis may be calculated from (SY1−SY2)+(SY3−SY4). 
         [0140]    In addition, an example of angular velocity calculation depending on this is as follows. 
         [0141]    As described above, when the internal frame  120  is rotated based on the Y axis with respect to the external frame  130  by the driving unit  190 , the first mass body  110   a  vibrates while being rotated together with the internal frame  120  based on the Y axis, and velocities (V x , V z ) are generated in the X and Z axis directions in the first mass body  110   a  depending on the vibrations. Here, when an angular velocity (Ω z , Ω x ) based on the Z or X axis is applied to the first mass body  110   a , Coriolis force (F y ) is generated in the Y axis direction. 
         [0142]    The first mass body  110   a  is displaced while being rotated based on the X axis with respect to the internal frame  120  by the Coriolis force (F y ), and the sensing unit  180  senses the displacement of the first mass body  110   a . In addition, the displacement of the first mass body  110   a  is sensed, thereby making it possible to calculate the Coriolis force (F y ). 
         [0143]    Therefore, the angular velocity (Ω x ) based on the X axis may be calculated through the Coriolis force (F y ) from F y =2mV z Ω x , and the angular velocity (Ω z ) based on the Z axis may be calculated through the Coriolis force (F y ) from F y =2mV x Ω z . 
         [0144]    As a result, in the angular velocity sensor  100  according to the first preferred embodiment of the present invention, the mass body part  110  and the internal frame are connected to the external frame so as to be displaceable only in a specific direction, such that sensing may be accurately performed and the angular velocity rotated based on the X or Z axis may be measured by the sensing unit  180 . 
         [0145]    Further, in the angular velocity sensor according to the first preferred embodiment of the present invention, the third flexible part  160  is disposed at the outer side of the internal frame in the displacement direction of the mass body part depending on the rotation of the mass body part, such that a size of the internal frame positioned in the external frame may be maximized in the Y axis direction. Therefore, the mass body part may be designed at a maximum size in the Y axis direction when it is formed, such that the sensing sensibility may be improved. 
         [0146]      FIG. 9  is a perspective view schematically showing an angular velocity sensor according to a second preferred embodiment of the present invention;  FIG. 10  is a schematic plan view of the angular velocity sensor shown in  FIG. 9 ;  FIG. 11  is a schematic cross-sectional view of the angular velocity sensor taken along the line A-A of  FIG. 9 ;  FIG. 12  is a schematic cross-sectional view of the angular velocity sensor taken along the line B-B of  FIG. 9 ; and  FIG. 13  is a schematic cross-sectional view of the angular velocity sensor taken along the line C-C of  FIG. 9 . 
         [0147]    As shown in  FIGS. 9 to 13 , the angular velocity sensor  200  according to the second preferred embodiment of the present invention is different only in a mass body part, connection directions in which each of the first and third flexible parts connects a mass body part and an internal frame to each other or connects the internal frame and an external frame to each other and organic couplings for implementing this from the angular velocity sensor  100  according to the first preferred embodiment of the present invention. That is, in the angular velocity sensor  200  according to the second preferred embodiment of the present invention and the angular velocity sensor  100  according to the first preferred embodiment of the present invention, specific shapes of the respective components, generation of displacements depending on the specific shapes, and methods of sensing the displacements are the same as each other. 
         [0148]    As shown in  FIGS. 9 to 13 , the angular velocity sensor  200  is configured to include a mass body part  210 , an internal frame  220 , an external frame  230 , first flexible parts  240 , second flexible parts  250 , third flexible parts  260 , and fourth flexible parts  270 . 
         [0149]    In addition, the first and second flexible parts  240  and  250 , which are flexible parts for sensing, are individually or selectively provided with a sensing unit  280 , and the third and fourth flexible parts  260  and  270 , which are flexible parts for vibrating, are individually or selectively provided with a driving unit  290 . 
         [0150]    The first flexible part  240 , which is the flexible part for sensing provided with the sensing unit is disposed at an outer side in a displacement direction of the mass body part  210  depending on rotation of the mass body part  210 . 
         [0151]    That is, the first flexible part  240  is disposed at the outer side in the displacement direction of the mass body part  210  at the time of the rotation of the mass body part  210 , such that the mass body part may be formed as largely as possible in the displacement direction (the Y axis direction), a maximum length (Lw2) is secured in the mass body part  210  as shown in  FIG. 10 , such that a maximum displacement is generated in the mass body part  210 , thereby making it possible to improve sensing sensibility. 
         [0152]    In addition, a connection direction in which the flexible part for sensing provided with the sensing unit  280  connects the mass body and the internal frame to each other may be in parallel with a connection direction in which the flexible part for vibrating provided with the driving unit  290  connects the internal frame and the external frame to each other. 
         [0153]    That is, the first flexible part  240 , which is the flexible part for sensing provided with the sensing unit  280  connects the mass body part  210  and the internal frame  220  to each other in a C1 direction corresponding to the X axis direction and the third flexible part  260  provided with the driving unit  290  connects the internal frame  220  and the external frame  230  to each other in a C2 direction corresponding to the X axis direction, such that the C1 direction corresponding to the connection direction of the first flexible part  240  and the C2 direction corresponding to the connection direction of the third flexible part  260  are in parallel with each other. 
         [0154]    Next, the mass body part  210 , which is displaced by Coriolis force, includes a first mass body  210   a  and a second mass body  210   b  and have the second flexible parts  250  connected thereto, respectively, so as to correspond to the centers of gravity of the first and second mass bodies  210   a  and  210   b.    
         [0155]    In addition, the first and second mass bodies  210   a  and  210   b  may have the same size. 
         [0156]    Further, the first and second mass bodies  210   a  and  210   b  are connected to the internal frame  220  by the first and second flexible parts  240  and  250 . 
         [0157]    Here, the first and second flexible parts  240  and  250  connect the mass body part  210  to the internal frame  220  in the X axis direction. Further, in the Y axis direction, the first flexible parts  240  are connected to both end portions of the first and second mass body  210   a  and  210   b , respectively, and the second flexible parts  250  are connected to central portions thereof, respectively. 
         [0158]    Further, one end of the first flexible part  240  is connected to the mass body part  210  and the other end thereof is connected to the internal frame  220 . To this end, the first flexible part  240  is extended in the X axis direction. 
         [0159]    Through the above-mentioned configuration, the first and second mass bodies  210   a  and  210   b  are displaced based on the internal frame  220  by bending of the first flexible part  240  and twisting of the second flexible part  250  when Coriolis force acts thereon. Here, the first and second mass bodies  210   a  and  210   b  are rotated based on the X axis with respect to the internal frame  220 . 
         [0160]    Meanwhile, although the case in which the first and second mass bodies  210   a  and  210   b  have a generally square pillar shape is shown, the first and second mass bodies  210   a  and  210   b  are not limited to having the above-mentioned shape, but may have all shapes known in the art. 
         [0161]    Further, the internal frame  220  supports the mass body part  210 . More specifically, the internal frame  220  has the first and second mass bodies  210   a  and  210   b  positioned therein and is connected to the mass body part  210  by the first and second flexible parts  240  and  250 . That is, the internal frame  220  allows a space in which the mass body part  210  may be displaced to be secured and becomes a basis when the mass body part  210  is displaced. In addition, the internal frame  220  may also cover only a portion of the mass body part  210 . 
         [0162]    Further, the sensing unit  280  and the driving unit  290  are formed on one surfaces of the first and third flexible parts  240  and  260 , respectively, as an example. 
         [0163]    Further, the internal frame  220  may be divided into two space parts  220   a  and  220   b  so that the first and second mass bodies  210   a  and  110   b  are positioned therein. In addition, the internal frame  220  may have a square pillar shape in which it has a square pillar shaped cavity formed at the center thereof, but is not limited thereto. 
         [0164]    In addition, the internal frame  220  may include protrusion coupling parts  221  formed at both sides thereof so that the third flexible part  260 , which is the flexible part for vibrating, is connected thereto, and the external frame  230  includes coupling protrusion parts  231  protruding toward the internal frame  220 , that is, formed in parallel with the protrusion coupling parts of the internal frame, so that the third flexible part  260 , which is the flexible part for vibrating, is connected thereto. 
         [0165]    Further, one end of the third flexible part  260  is coupled to the protrusion coupling part  221  of the internal frame and the other end thereof is coupled to the coupling protrusion part  231  of the external frame. To this end, the third flexible part  260  is extended in the X axis direction. 
         [0166]    More specifically, the protrusion coupling parts  221  of the internal frame are formed at both end portions of the internal frame in the X axis direction so as to be extended in the X axis direction in the Y axis direction, and the coupling protrusion parts  231  of the external frame  230  are extended toward the internal frame in the Y axis direction. In addition, the third flexible part  260  is disposed so that both end portions thereof in the X axis direction are coupled to the protrusion coupling part  21  and the coupling protrusion part  231 . 
         [0167]    Therefore, both of the first flexible part  240  provided with the sensing unit  280  and the third flexible part  260  provided with the driving unit  290  are disposed to be extended in the X axis direction. That is, a connection direction in which the first flexible part  240  connects the mass body part to the internal frame and a connection direction in which the third flexible part  260  connects the internal frame to the external frame are in parallel with each other. 
         [0168]    In other words, the connection direction in which the first flexible part  240  connects the mass body part  210  to the internal frame  220 , that is, the direction in which the first flexible part  240  is extended is in parallel with the connection direction in which the third flexible part  260  connects the internal frame  220  to the external frame  230 , that is, the direction in which the third flexible part  260  is extended. 
         [0169]    Further, the second and fourth flexible parts  250  and  270  are disposed in a direction in which they are perpendicular to each other. 
         [0170]    As described above, since the first flexible part  240 , the second flexible part  250 , the third flexible part  260 , and the fourth flexible part  270  of the angular velocity sensor  200  according to the second preferred embodiment of the present invention have the same shape as those of the first flexible part  140 , the second flexible part  150 , the third flexible part  160 , and the fourth flexible part  170  of the angular velocity sensor  100  according to the first preferred embodiment of the present invention, a description thereof will be omitted. 
         [0171]    Through the configuration as described above, in the angular velocity sensor  200  according to the second preferred embodiment of the present invention, the mass body part and the internal frame are connected to the external frame so as to be displaceable only in a specific direction, such that sensing may be accurately performed and the angular velocity rotated based on the X or Z axis may be measured by the sensing unit. 
         [0172]    In addition, through the configuration as described above, in the angular velocity sensor  200  according to the second preferred embodiment of the present invention, the first flexible part  240  is disposed at the outer side of the mass body part in the displacement direction of the mass body part depending on the rotation of the mass body part  210 , such that the mass body part may be designed at a maximum size in the Y axis direction when it is formed. 
         [0173]    That is, since the mass body part is rotated based on the X axis and is displaced in the Y axis direction, a size of the mass body part in the Y axis direction as large as possible should be secured in order to generate a maximum displacement. In this case, sensing sensitivity is improved. Therefore, the angular velocity sensor  200  according to the second preferred embodiment of the present invention may improve the sensing sensitivity through optimal structures and organic couplings of the first flexible part  240 , the mass body part  210 , and the internal frame  220  described above. 
         [0174]      FIG. 14  is a plan view schematically showing an angular velocity sensor according to a third preferred embodiment of the present invention. 
         [0175]    As shown in  FIG. 14 , the angular velocity sensor  300  according to the third preferred embodiment of the present invention is different only in an organic coupling between a mass body part and a first flexible part from the angular velocity sensor  100  according to the first preferred embodiment of the present invention. That is, in the angular velocity sensor  300  according to the third preferred embodiment of the present invention and the angular velocity sensor  100  according to the first preferred embodiment of the present invention, specific shapes, organic couplings and generation of displacements depending on them, and methods of sensing the displacements of remaining components are the same as each other. 
         [0176]    More specifically, the angular velocity sensor  300  is configured to include a mass body part  310 , an internal frame  320 , an external frame  330 , first flexible parts  340 , second flexible parts  350 , third flexible parts  360 , and fourth flexible parts  370 . 
         [0177]    In addition, the first and second flexible parts  340  and  350 , which are flexible parts for sensing, are individually or selectively provided with a sensing unit  380 , and the third and fourth flexible parts  360  and  370 , which are flexible parts for vibrating, are individually or selectively provided with a driving unit  390 . 
         [0178]    In addition, the flexible part for vibrating provided with the driving unit  390  is disposed at an outer side in a displacement direction of the mass body part  310  depending on rotation of the mass body part  310 , and the flexible part for sensing provided with the sensing unit  380  is disposed at an outer side in the displacement direction of the mass body part depending on the rotation of the mass body part. 
         [0179]    That is, the first flexible part  340 , which is the flexible part for sensing, is disposed at the outer side in the displacement direction of the mass body part  310  depending on the rotation of the mass body part  310 , such that it may be formed as largely as possible in the displacement direction (the Y axis direction) of the mass body part. 
         [0180]    In addition, the third flexible part  360 , which is the flexible part for vibrating provided with the driving unit  390 , is disposed at the outer side of the internal frame in the displacement direction of the mass body part depending on the rotation of the mass body part. That is, as described above with reference to the enlarged view of  FIG. 2 , the third flexible part  360  is disposed at the outer side of the internal frame in the displacement direction of the mass body  310 , such that the internal frame  320  may be formed as largely as possible in the displacement direction (the Y axis direction) of the mass body part and a maximum length Lw3 of the mass body part  310  from the center of rotation may be secured. Therefore, a maximum displacement is generated in the mass body  310 , thereby making it possible to improve the sensing sensibility. 
         [0181]    In addition, a connection direction C1 in which the first flexible part  340  corresponding to the flexible part for sensing provided with the sensing unit  380  connects the mass body part  310  and the internal frame  320  to each other may be perpendicular to a connection direction C2 in which the third flexible part  360  corresponding to the flexible part for vibrating provided with the driving unit connects the internal frame  320  and the external frame  330  to each other. 
         [0182]    In addition, the first and second flexible parts  340  and  350  connect the mass body part  310  to the internal frame  320  in the X axis direction. Further, in the Y axis direction, the first flexible parts  340  are connected to both end portions of the first and second mass body  310   a  and  310   b , respectively, and the second flexible parts  350  are connected to central portions thereof, respectively. 
         [0183]    Further, one end of the first flexible part  340  is connected to the mass body part  310  and the other end thereof is extended in the X axis direction so as to be connected to the internal frame  320 . 
         [0184]    In addition, since the first flexible part  340 , the second flexible part  350 , the third flexible part  360 , the fourth flexible part  370 , and a protrusion coupling part  321  of the angular velocity sensor  300  according to the third preferred embodiment of the present invention have the same shape as those of the first flexible part  140 , the second flexible part  150 , the third flexible part  160 , the fourth flexible part  170 , and the protrusion coupling part  121  of the angular velocity sensor  100  according to the first preferred embodiment of the present invention, a description thereof will be omitted. 
         [0185]    According to the preferred embodiments of the present invention, it is possible to provide an angular velocity sensor capable of removing interference between a driving mode and a sensing mode and decreasing an effect due to a manufacturing error by driving a frame and a mass body by a single driving part to individually generate driving displacement and sensing displacement of the mass body and forming flexible parts so that the mass body is movable only in a specific direction and capable of improving sensitivity by maximizing a mass body part in a limited region due to an optimal structure. 
         [0186]    Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, it will be appreciated that the present invention is not limited thereto, and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention. Particularly, the present invention has been described based on the “X axis”, the “Y axis”, and the “Z axis”, which are defined for convenience of explanation. Therefore, the scope of the present invention is not limited thereto. 
         [0187]    Accordingly, any and all modifications, variations or equivalent arrangements should be considered to be within the scope of the invention, and the detailed scope of the invention will be disclosed by the accompanying claims.