Abstract:
Disclosed herein are an apparatus and a method for driving an inertial sensor. The apparatus for driving an inertial sensor includes a detection unit that detects first acceleration detection voltage and detects angular velocity detection voltage when a wake up signal is input; a wake up signal generation unit that generates the wake up signal when the total of acceleration detection voltage is larger than predetermined voltage; a phase conversion unit that generates driving voltage and inversion driving voltage of the corresponding axis; a driving unit that vibrates the inertial sensor; and a control unit that performs a control to wake up the detection unit, the phase conversion unit, and the driving unit or convert them into a sleep mode according to a control signal, whereby power consumption can be minimized in an apparatus requiring low power like mobile environment.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2011-0045109, filed on May 13, 2011, entitled “Apparatus And Method For Driving Inertial Sensor” which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to an apparatus and a method for driving an inertial sensor. 
     2. Description of the Prior Art 
     An apparatus for driving an inertial sensor is an apparatus capable of sensing angular velocity corresponding to deformations due to acceleration and rotation motion in response to linear motions. Recently, an inertial sensor has been used as 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, 
     Acceleration of the apparatus for driving an inertial sensor may be obtained by Newton&#39;s law of motion “F=ma”, where “F” is force applied to an object, “m” is a mass of an object, and “a” is acceleration to be measured. Therefore, the acceleration a may be obtained by measuring force F applied to an object and dividing the measured force by a mass m of an object that is a predetermined value. 
     Further, angular velocity of the inertial sensor may be obtained by Coriolis force “F=2 mΩ·v”, where “F” represents the Coriolis force applied to an object, “m” represents a mass of an object, “Ω” represents angular velocity to be measured, and “v” represents motion velocity of an object. 
     In this case, since the motion velocity v of the object and the mass m of the object are a value known in advance, the angular velocity Ω may be obtained by measuring the Coriolis force (F) applied to the object. Meanwhile, the direction of the Coriolis force F, the direction of the motion velocity v, and a reference axis of the angular velocity Ω need to form a right angle to each other. 
     In this case, in order to detect the angular velocity of the inertial sensor, a considerable amount of power is consumed since the angular velocity of an axis vertical to the vibration axis is measured by vibrating the inertial sensor in a direction of each axis of the inertial sensor. 
     Therefore, there is a problem in that the apparatus for driving an inertial sensor according to the prior art is not appropriate to use in mobile environments requiring low power. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to provide an apparatus and a method for driving an inertial sensor capable of minimizing power consumption by waking up components sensing angular velocity when acceleration of a predetermined value or more is sensed from the inertial sensor. 
     According to a preferred embodiment, there is provided an apparatus for driving an inertial sensor, including: a detection unit that detects first acceleration detection voltage corresponding to acceleration of each axis of the inertial sensor and detects angular velocity detection voltage corresponding to angular velocity of each axis of the inertial sensor when a wake up signal is input; a wake up signal generation unit that generates the wake up signal when second acceleration detection voltage calculated from the first acceleration detection voltage of each axis is larger than predetermined reference voltage; a phase conversion unit that generates driving voltage and inversion driving voltage of the corresponding axis by shifting the first acceleration detection voltage of each axis by a predetermined phase so as to vibrate the inertial sensor in directions of each axis when the wake signal is input; a driving unit that provides the driving voltage and the inversion driving voltage of the corresponding axis to corresponding driving electrodes when the wake up signal is input so as to vibrate the inertial sensor in the directions of the corresponding axis; and a control unit that performs a control to wake up the detection unit, the phase conversion unit, and the driving unit or convert the detection unit, the phase conversion unit, and the driving unit into a sleep mode according to a control signal. 
     The detection unit may include: a first detector that detects the first acceleration detection voltage corresponding to the acceleration of each axis due to the deformations caused by linear motions of each axis of the inertial sensor; a second detector that detects angular velocity detection voltage corresponding to the angular velocity of each axis due to the deformations caused by Coriolis force and vibrations of each axis of the inertial sensor when the wake up signal is input; and a switching unit that is switched to disconnect the first detector from the second detector according to a control signal when the wake up signal of the control unit is absent and to connect the first detector to the second detector according to the control signal when the wake up signal of the control unit is present. 
     The first detector may include: a first detection amplifier that amplifies output voltage from a positive detection electrode disposed on a first axis of the inertial sensor; a second detection amplifier that amplifies output voltage from a negative detection electrode disposed on the first axis of the inertial sensor; a third detection amplifier that amplifies output voltage from a positive detection electrode disposed on a second axis of the inertial sensor; a fourth detection amplifier that amplifies output voltage from a negative detection electrode disposed on the second axis of the inertial sensor; a first detection subtracter that outputs the first acceleration detection voltage of the first axis corresponding to the first axis acceleration calculated by subtracting the output voltage from the second detection amplifier from the output voltage from the first detection amplifier; a second detection subtracter that outputs the first acceleration detection voltage of the second axis corresponding to the second axis acceleration calculated by subtracting the output voltage from the fourth detection amplifier from the output voltage from the third detection amplifier; and a first detection adder that outputs the first acceleration detection voltage of a third axis corresponding to the third axis acceleration calculated by adding the output voltage from the first detection amplifier, the output voltage from the second detection amplifier, the output voltage from the third detection amplifier, and the output voltage from the fourth amplifier. 
     The second detector may include: a first detection multiplier that outputs the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage for vibrating the inertial sensor in a direction of the third axis; a second detection multiplier that outputs the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage for vibrating the inertial sensor in a direction of the third axis; and a third detection multiplier that outputs the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage for vibrating the inertial sensor in a direction of the first axis. 
     The first detection multiplier may output third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage for vibrating the inertial sensor in a direction of the second axis. 
     The second detection multiplier may output the third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage for vibrating the inertial sensor in a direction of the first axis. 
     The third detection multiplier may output the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage for vibrating the inertial sensor in the direction of the second axis. 
     The switching unit may include: a first switch stage that is switched to disconnect or connect the first detection subtracter from or to the first detection multiplier according to the control signal of the control unit; a second switch stage that is switched to disconnect or connect the second detection subtracter from or to the second detection multiplier according to the control signal of the control unit; and a third switch stage that is switched to disconnect or connect the first detection adder from or to the third detection multiplier according to the control signal of the control unit. 
     The wake up signal generation unit may include: a second detection adder that outputs the second acceleration detection voltage calculated by adding the first acceleration detection voltage of each axis detected through the detection unit; a high frequency filter that is filtered to remove high frequency signals in order to remove noise from the output second acceleration detection voltage; and a comparator that generates the wake up signals when the second acceleration detection voltage is larger than the reference voltage by comparing the filtered second acceleration detection voltage with the reference voltage. 
     The driving unit may include: a first driving amplifier that amplifies the first axis driving voltage or the third axis driving voltage generated from the phase conversion unit and provides the amplified first axis driving voltage or the amplified third axis driving voltage to a positive driving electrode disposed on the first axis of the inertial sensor; a second driving amplifier that amplifies the first axis inversion driving voltage or the third axis inversion driving voltage generated from the phase conversion unit and provides the amplified first axis inversion driving voltage or the amplified inversion third axis driving voltage to a negative driving electrode disposed on the first axis of the inertial sensor; a third driving amplifier that amplifies the second axis inversion driving voltage or the third axis inversion driving voltage generated from the phase conversion unit and provides the amplified second axis driving voltage or the amplified third axis driving voltage to a positive driving electrode disposed on the second axis of the inertial sensor; and a fourth driving amplifier that amplifies the second axis inversion driving voltage or the third axis inversion driving voltage generated from the phase conversion unit and provides the amplified second axis driving voltage or the amplified third axis driving voltage to a negative driving electrode disposed on the second axis of the inertial sensor. 
     The control unit may turn off the switching unit according to the control signal when the wake up signal is absent if the angular velocity detection voltage of each axis detected from the second detector is absent for the predetermined time to perform a control to convert the second detector, the phase conversion unit, and the driving unit into a sleep mode. 
     According to another preferred embodiment of the present invention, there is provided a method for driving an inertial sensor, including: (A) detecting first acceleration detection voltage corresponding to acceleration of each axis of an inertial sensor by a first detector; (B) generating a wake up signal by a wake up signal generation unit when second acceleration detection voltage calculated from the first acceleration detection voltage of each axis is larger than predetermined reference voltage; and (C) detecting angular velocity detection voltage corresponding to angular velocity of each axis of the inertial sensor by the woken up second detector, the phase conversion unit, and the driving unit by receiving the wake up signal. 
     The method for driving an inertial sensor may further include: (D) converting the second detector, the phase conversion unit, and the driving unit to be in a sleep mode by the control unit when the angular velocity detection voltage of each axis is not detected for the predetermined time. 
     The (A) may include: (A-1) amplifying first output voltage from a positive detection electrode and second output voltage from a negative detection electrode disposed on a first axis of the inertial sensor by the first detector and then, outputting first acceleration detection voltage of a first axis due to the deformations caused by a linear motion of the first axis by subtracting the amplified second output voltage from the amplified first output voltage; (A-2) amplifying third output voltage from a positive detection electrode and fourth output voltage from a negative detection electrode disposed on a second axis of the inertial sensor by the first detector and then, outputting first acceleration detection voltage of a second axis due to the deformations caused by a linear motion of the second axis by subtracting the amplified fourth output voltage from the amplified third output voltage; and (A-3) adding the amplified first output voltage, the amplified second output voltage, the amplified third output voltage, and the amplified fourth output voltage by the first detector to output the first acceleration detection voltage of a third axis due to the deformations caused by a linear motion of the third axis of the inertial sensor. 
     The (B) may include: (B-1) calculating second acceleration detection voltage by adding the first acceleration detection voltage of each axis; (B-2) determining whether the calculated second acceleration detection voltage is larger than the reference voltage; and (B-3) generating a wake up signal when the second acceleration detection voltage is larger than the reference voltage. 
     The (C) may include: (C-1) generating driving voltage and inversion driving voltage of the corresponding axis by shifting the first acceleration detection voltage of each axis by a predetermined phase so as to vibrate the inertial sensor in directions of each axis by the phase conversion unit when the wake up signal is input; (C-2) vibrating the inertial sensor in the direction of the corresponding axis by providing the driving voltage and the inversion driving voltage of the corresponding axis to the corresponding driving voltage through the driving unit when the wake up signal is input; and (C-3) detecting angular velocity detection voltage corresponding to angular velocity of each axis due to the deformations caused by Coriolis force and vibrations of the corresponding axis of the inertial sensor by a second detector when the wake up signal is input. 
     The (C-3) may include: outputting the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage of the inertial sensor; outputting the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the third axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the third axis according to the third axis driving voltage of the inertial sensor; and outputting the third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the first axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage of the inertial sensor. 
     The (C-3) may include: outputting the second axis angular velocity detection voltage corresponding to the second axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage of the inertial sensor; outputting the third axis angular velocity detection voltage corresponding to the third axis angular velocity calculated by multiplying the first acceleration detection voltage of the second axis re-detected through the first detector by the first axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the first axis according to the first axis driving voltage of the inertial sensor; and outputting the first axis angular velocity detection voltage corresponding to the first axis angular velocity calculated by multiplying the first acceleration detection voltage of the third axis re-detected through the first detector by the second axis driving voltage due to the deformations caused by the Coriolis force and the vibrations of the second axis according to the second axis driving voltage of the inertial sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an apparatus for driving an inertial sensor according to a preferred embodiment of the present invention. 
         FIG. 2  is a circuit diagram of the apparatus for driving an inertial sensor shown in  FIG. 1 . 
         FIG. 3  is a flow chart of a method for driving an inertial sensor according to another preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various features and advantages of the present invention will be more obvious from the following description with reference to the accompanying drawings. 
     The terms and words used in the present specification and claims should not be interpreted as being limited to typical meanings or dictionary definitions, but should be interpreted as having meanings and concepts relevant to the technical scope of the present invention based on the rule according to which an inventor can appropriately define the concept of the term to describe most appropriately the best method he or she knows for carrying out the invention. 
     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 the specification, in adding reference numerals to components throughout the drawings, it is to be noted that like reference numerals designate like components even though components are shown in different drawings. Terms used in the specification, ‘first’, ‘second’, etc. can be used to describe various components, but the components are not to be construed as being limited to the terms. The terms are only used to differentiate one component from other components. Further, in describing the present invention, a detailed description of related known functions or configurations will be omitted so as not to obscure the subject of the present invention. 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a block diagram of an apparatus for driving an inertial sensor according to a preferred embodiment of the present invention and  FIG. 2  is a circuit diagram of the apparatus for driving an inertial sensor shown in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the apparatus for driving an inertial sensor according to the preferred embodiment of the present invention is configured to include an inertial sensor  10 , a detection unit  20 , a wake up signal generation unit  30 , a phase conversion unit  40 , a driving unit  50 , and a control unit  60 . 
     The inertial sensor  10  is a sensor that senses acceleration according to a linear movement of each axis and angular velocity according to a rotation movement of each axis. 
     The inertial sensor  10 , the detection unit  20 , and the driving unit  50  may be implemented by forming a plurality of electrodes in a single piezoelectric body that is a plate-shaped structure. 
     For example, the detection unit  20  may be implemented by forming four detection electrodes in a piezoelectric body and the driving unit  50  may be implemented by forming four driving electrodes. 
     In this configuration, the four detection electrodes are configured to include a positive detection electrode (hereinafter, referred to as a ‘first detection electrode’) and a negative detection electrode (hereinafter, referred to as a ‘second detection electrode’) that are disposed on an X axis of the inertial sensor  10  and a positive detection electrode (hereinafter, referred to as a ‘third detection electrode’) and a negative detection electrode (hereinafter, referred to as a ‘fourth detection electrode’) that are disposed on a Y axis of the inertial sensor  10 . 
     Further, the four driving electrodes are configured to include a positive driving electrode (hereinafter, referred to as a ‘first driving electrode’) and a negative driving electrode (hereinafter, referred to as a ‘second driving electrode’) that are disposed on the X axis of the inertial sensor  10  and a positive driving electrode (hereinafter, referred to as a ‘third driving electrode’) and a negative driving electrode (hereinafter, referred to as a ‘fourth driving electrode’) that are disposed on the Y axis of the inertial sensor  10 . 
     The detection unit  20  is configured to include a first detector  21  that detects first acceleration detection voltage (for example, M X1 , M Y1 , M Z1  or M X2 , M Y2 , M Z2 ) corresponding to acceleration of each axis of the inertial sensor  10 , a second detector  25  that detects angular velocity detection voltage (for example, W X , W Y , W Z ) that corresponds to angular velocity of each axis of the inertial sensor  10  when a wake up signal is input, and a switching unit  23  that connects and disconnects between the first detector  21  and the second detector  25  according to a predetermined control signal. 
     In this configuration, the first detector  21  is in an on state at all times, but the second detector  25  is initially in an off state (that is, a sleep/standby mode) and is then woken up according to a predetermined control signal (for example, according to whether the wake up signal is present) or, to the contrary, again reconverted from the woken up state to the off state (that is, a sleep/standby mode). 
     In detail, since the first detector  21  is in the on state at all times, it detects the first acceleration detection voltage corresponding to acceleration of each axis due to the deformations caused by linear motions of each axis of the inertial sensor  10 . 
     The first detector  21  is configured to include a first detection amplifier  21 - 1 , a second detection amplifier  21 - 2 , a third detection amplifier  21 - 3 , a fourth detection amplifier  21 - 4 , a first detection subtracter  21 - 5 , a second detection subtracter  21 - 6 , and a first detection adder  21 - 7 . 
     The first detection amplifier  21 - 1  amplifies and outputs the output voltage of the first detection electrode disposed on the X axis of the inertial sensor  10  and the second detection amplifier  21 - 2  amplifies and outputs the output voltage of the second detection electrode disposed on the X axis of the inertial sensor  10 . 
     The third detection amplifier  21 - 3  amplifies and outputs the output voltage of the third detection electrode disposed on the Y axis of the inertial sensor  10  and the fourth detection amplifier  21 - 4  amplifies and outputs the output voltage of the fourth detection electrode disposed on the Y axis of the inertial sensor  10 . 
     The first detection subtracter  21 - 5  outputs the X-axis first acceleration detection voltage M X1  corresponding to the X-axis acceleration calculated by subtracting the output voltage from the second detection amplifier  21 - 2  from the output voltage from the first detection amplifier  21 - 2 . 
     For example, when the output voltage of the first detection electrode, which is output from the first detection amplifier  21 - 1 , is referred to as S X1  and the output voltage of the second detection electrode, which is output from the second detection amplifier  21 - 2 , is referred to as S X2 , the X-axis first acceleration detection voltage M X1  calculated by the first detection subtracter  21 - 5  becomes S X1 −S X2 . 
     The second detection subtracter  21 - 6  outputs the Y-axis first acceleration detection voltage M X1  corresponding to the X-axis acceleration calculated by subtracting the output voltage from the fourth detection amplifier  21 - 4  from the output voltage from the third detection amplifier  21 - 3 . 
     For example, when the output voltage of the third detection electrode, which is output from the third detection amplifier  21 - 3 , is referred to as S Y1 , the output voltage of the fourth detection electrode, which is output from the fourth detection amplifier  21 - 4  is referred to as S Y2 , the Y-axis first acceleration detection voltage M Y1  calculated through the second detection subtracter  21 - 6  is S Y1 −S Y2 . The first detection adder  21 - 7  outputs the Z-axis first acceleration detection voltage M Z1  corresponding to the Z-axis acceleration calculated by adding the output voltage S X1  of the first detection electrode, which is output from the first detection amplifier  21 - 1 , the output voltage S X2  of the second detection electrode, which is output from the second detection amplifier  21 - 2 , the output voltage S Y1  of the third detection electrode, which is output from the third detection amplifier  21 - 3 , and the output voltage S Y2  of the fourth detection electrode, which is output from the fourth detection amplifier  21 - 4 . 
     For example, the Z-axis first acceleration detection voltage M Z1  calculated by the first detection adder  21 - 7  is S X1 +S X2 +S Y1 +S Y2 . 
     Meanwhile, when the second detector  25  is in an off state (that is, a sleep/standby mode) and is then woken up by receiving the wake up signal, it detects the angular velocity detection voltage W X , W Y , and W Z  that correspond to the angular velocity of each axis due to the deformations caused by the Coriolis force and the vibrations of each axis of the inertial sensor  10 . 
     The second detector  25  is configured to include a first detection multiplier  25 - 1 , a second detection multiplier  25 - 2 , and a third detection multiplier  25 - 3 , as shown in  FIG. 2 . 
     The first detection multiplier  25 - 1  outputs the Y-axis angular velocity detection voltage W Y  corresponding to the Y-axis angular velocity calculated by multiplying the X-axis first acceleration detection voltage M X2  re-detected through the first detector  21  by Z-axis driving voltage D Z , due to the deformations caused by the Coriolis force and the vibrations of the Z axis depending on the Z-axis driving voltage D Z  for vibrating the inertial sensor  10  in the Z-axis direction. 
     Further, the first detection multiplier  25 - 1  may also output the Z-axis angular velocity detection voltage W Z  corresponding to the Z-axis angular velocity calculated by multiplying the X-axis first acceleration detection voltage M X2  re-detected through the first detector  21  by X-axis driving voltage D X , due to the deformations caused by the Coriolis force and the Y-axis vibrations depending on the Y-axis driving voltage D Y  for vibrating the inertial sensor  10  in the Y-axis direction. 
     The second detection multiplier  25 - 2  outputs the X-axis angular velocity detection voltage W X  corresponding to the X-axis angular velocity calculated by multiplying the Y-axis first acceleration detection voltage M Y2  re-detected through the first detector  21  by Z-axis driving voltage D Z , due to the deformation caused by the Coriolis force and the Z-axis vibrations depending on the Z-axis driving voltage D Z  for vibrating the inertial sensor  10  in the Z-axis direction. 
     Further, the second detection multiplier  25 - 2  may also output the Z-axis angular velocity detection voltage W Z  corresponding to the Z-axis angular velocity calculated by multiplying the Y-axis first acceleration detection voltage M Y2  re-detected through the first detector  21  by Y-axis driving voltage D Y , due to the deformations caused by the Coriolis force and the vibrations of the X axis depending on the X-axis driving voltage D X  for vibrating the inertial sensor  10  in the X-axis direction. 
     The third detection multiplier  25 - 3  outputs the Y-axis angular velocity detection voltage W Y  corresponding to the Y-axis angular velocity calculated by multiplying the Z-axis first acceleration detection voltage M Z2  re-detected through the first detector  21  by X-axis driving voltage D X , due to the deformations caused by the Coriolis force and the vibrations of the X axis depending on the X-axis driving voltage D X  for vibrating the inertial sensor  10  in the X-axis direction. 
     Further, the third detection multiplier  25 - 3  may also output the X-axis angular velocity detection voltage W X  corresponding to the X-axis angular velocity calculated by multiplying the Z-axis first acceleration detection voltage M Z2  re-detected through the first detector  21  by Y-axis driving voltage D Y , due to the deformations caused by the Coriolis force and the vibrations of the Y axis depending on the Y-axis driving voltage D Y  for vibrating the inertial sensor  10  in the Y-axis direction. 
     The switching unit  23  is disposed between the first detector  21  and the second detector  25 , and is switched to disconnect the first detector  21  from the second detector  25  according to a predetermined control signal, that is, a control signal when the wake up signal of the control unit  60  to be described below is absent and to connect the first detector  21  to the second detector  25  according to the control signal when the wake up signal of the control unit  60  is present. 
     That is, when the wake up signal is absent, the switching unit  23  is in an off state to operate only the first detector  21 , such that the first acceleration detection voltage of each axis is output to sense the acceleration and the second detector  25  and the phase conversion unit  40  and the driving unit  50  to be described below are in the sleep/standby mode. 
     On the other hand, when the wake up signal is present, the switching unit  23  is in an on state to wake up the second detector  25 , the phase conversion unit  40 , and the driving unit all of which are in the sleep/standby mode, thereby outputting the angular velocity voltage of each axis to sense the angular velocity. 
     As shown in  FIG. 2 , the switching unit  23  is configured to include a first switch stage  23 - 1 , a second switch stage  23 - 2 , and a third switch stage  23 - 3 . 
     The first switch stage  23 - 1  is switched to disconnect or connect the second detection subtracter  21 - 5  from or to the second detection multiplier  25 - 1  according to the control signal of the control unit  60 . 
     The second switch stage  23 - 2  is switched to disconnect or connect the second detection subtracter  21 - 6  from or to the second detection multiplier  25 - 2  according to the control signal of the control unit  60 . 
     The third switch stage  23 - 3  is switched to disconnect or connect the first detection adder  21 - 7  from or to the third detection multiplier  25 - 3  according to the control signal of the control unit  60 . 
     The wake up signal generation unit  30  receives the first acceleration detection voltage M X1 , M Y1  and M Z1  of the X axis, the Y axis, and the Z axis that are detected in the first detector  21  and generates the wake up signal when the second acceleration detection voltage M T =M X1 +M Y1 +M Z1  calculated therefrom is larger than a predetermined reference voltage V ref  and provides the generated wake up signal to the switching unit  23  of the detection unit  20 , the second detector  25 , the phase conversion unit  40  to be described below, the driving unit  50 , and the control unit  60 . 
     In detail, the wake up signal generation unit  30  is configured to include a second detection adder  31 , a high frequency filter  32 , and a comparator  33  as shown in  FIG. 2 . 
     The second detection adder  31  outputs the second acceleration detection voltage M T =M X1 +M Y1 +M Z1  calculated by adding the first acceleration detection voltage M X1 , M Y1 , and M Z1  of each axis detected by the first detector  21  of the detection unit  20 . 
     The high frequency filter  32  is filtered to remove the high frequency signal, in order to remove noise from the second acceleration detection voltage M T =M X1 +M Y1 +M Z1 . 
     The comparator  33  compares the filtered second acceleration detection voltage M T =M X1 +M Y1 +M Z1  with the reference voltage V ref  to generate the wake up signal when the second acceleration detection voltage M T =M X1 +M Y1 +M Z1  is larger than the reference voltage V ref . 
     The phase conversion unit  40  shifts the first acceleration detection voltage M X1 , M Y1 , and M Z1  of the axes by a predetermined phase so as to vibrate the inertial sensor  10  in the directions of each axis when the wake up signal generated as described above is input, thereby generating the driving voltage D X , D Y , and D Z  and inversion driving voltage −D X , −D Y , and −D Z  so as to be provided to the driving unit  50  to be described below and the second detector  25 . 
     For example, the phase conversion unit  40  applies the X-axis driving voltage D X  that delays the X-axis first acceleration detection voltage M X1  by 90° and the X-axis inversion driving voltage −D X  that inverts the X-axis driving voltage D X  by 180° to the driving unit  50  and the second detector  25  so as to vibrate the inertial sensor  10  in the X axis. 
     Similarly, the phase conversion unit  40  applies the Y-axis driving voltage D Y  that delays the Y-axis first acceleration detection voltage M Y1  by 90° and the Y-axis inversion driving voltage −D Y  that inverts the Y-axis driving voltage D Y  by 180° to the driving unit  50  and the second detector  25  so as to vibrate the inertial sensor  10  in the Y axis. 
     Further, the phase conversion unit  40  applies the Z-axis driving voltage D Z  that delays the Z-axis first acceleration detection voltage M Z1  by 90° and the Z-axis inversion driving voltage −D Z  that inverts the Z-axis driving voltage D Z  by 180° to the driving unit  50  and the second detector  25  so as to vibrate the inertial sensor  10  in the Z axis. 
     The driving unit  50  provides the driving voltage D X , D Y , and D Z  and the inversion driving voltage −D X , −D Y , and −D Z  of the corresponding axes generated from the phase conversion unit  40  to the corresponding driving electrode to vibrate the inertial sensor  10  in the direction of the corresponding axis, when the wake up signal generated as described above is input. 
     In detail, as shown in  FIG. 2 , the driving unit  50  is configured to include a first drive amplifier  51 , a second drive amplifier  52 , a third drive amplifier  53 , and a fourth driver amplifier  54 . 
     The first drive amplifier  51  amplifies the X-axis driving voltage D X  or the Z-axis driving voltage D Z  generated from the phase conversion unit  40  so as to be provided to the first driving electrode disposed on the X axis of the inertial sensor  10 . 
     The second drive amplifier  52  amplifies the X-axis inversion driving voltage −D X  of the X-axis driving voltage D X  or the Z-axis inversion driving voltage −D Z  of the Z-axis driving voltage D Z  generated from the phase conversion unit  40  so as to be provided to the second driving electrode disposed on the X axis of the inertial sensor  10 . 
     The third drive amplifier  53  amplifies the Y-axis driving voltage D Y  or the Z-axis driving voltage D Z  generated from the phase conversion unit  40  so as to be provided to the third driving electrode disposed on the Y axis of the inertial sensor  10 . 
     The fourth drive amplifier  54  amplifies the Z-axis inversion driving voltage −D Z  of the Y-axis inversion driving voltage −D Y  or the Z-axis driving voltage D Z  of the Y-axis driving voltage D Y  generated from the phase conversion unit  40  so as to be provided to the fourth driving electrode disposed on the Y axis of the inertial sensor  10 . 
     The control unit  60  generally controls the inertial sensor drive apparatus according to the preferred embodiment of the present invention. 
     The control unit  60  controls the first detector  21  of the detection unit  20  according to the control signal when the wake up signal is absent, thereby performing a control to sense the acceleration of each axis of the inertial sensor  10 . 
     In addition, the control unit  60  controls the switching unit  23  of the detection unit  20 , the second detector  25 , the phase conversion unit  40 , and the driving unit  50  according to the control signal when the wake up signal is present, thereby performing a control to sense the angular velocity of each axis of the inertial sensor  10 . 
     In detail, the control unit  60  controls the on/off of the switching unit  23  so as to disconnect the first detector  21  from the second detector  25  according to the control signal when the wake up signal is absent and connect the first detector  21  to the second detector  25  according to the control signal when the wake up signal is present. 
     That is, the control unit  60  generates the control signal at the time of the presence of the wake up signal when the wake up signal is input from the wake up signal generation unit  30  and turns-on the switching unit  23  according to the control signal when to connect the first detector  21  to the second detector  25 , thereby performing a control to wake up the second detector  25 , the phase conversion unit  40 , and the driving unit  50 . 
     In addition, the control unit  60  generates the control signal at the time of the absence of the wake up signal when the angular velocity detection voltage W X , W Y , and W Z  of each axis is not detected by the second detector  25  for a predetermined time and turns-off the switching unit  23  according to the control signal to disconnect the first detector  21  from the second detector  25 , thereby again reconverting the second detector  25 , the phase conversion unit  40 , and the driving unit  50  to be in a the sleep/standby mode. 
       FIG. 3  is a flow chart of a method for driving an inertial sensor according to another preferred embodiment of the present invention. 
     Referring to  FIG. 3 , in the method for driving an inertial sensor according to a preferred embodiment of the present invention, the control unit  60  performs a control so that the first detector  21  of the detection unit  20  determines whether the output voltage S X1 , S X2 , S Y1 , and S Y2  output from the detection electrode of the X axis and the Y axis is present due to the deformations caused by the linear motion of each axis in the sleep/standby mode state (S 31 ). 
     At step S 31 , when the output voltage S X1 , S X2 , S Y1 , and S Y2  output from the detection electrode of the X axis and the Y axis is present, the first acceleration detection voltage M X1 , M Y1 , and M Z1  corresponding to the acceleration of each axis of the inertial sensor  10  is output through the first detector  21  and the second acceleration detection voltage M T  is calculated therefrom (S 32 ). 
     In this case, the second acceleration detection voltage M T  adds the first acceleration detection voltages may be calculated (M T =M X1 +M Y1 +M Z1 ) by adding M X1 , M Y2 , and M Z2  of each axis by the second detection adder  31  of the wake up signal generation unit  30 . 
     In detail, the step S 32  amplifies the first output voltage from the first detection electrode and the second output voltage from the second detection electrode disposed on the X axis of the inertial sensor  10  by the first detector  21  and then subtracts the amplified second output voltage from the amplified first output voltage to output the X-axis first acceleration detection voltage M X1  corresponding to the deformations due to the X-axis linear motion and amplifies the third output voltage from the third detection electrode and the fourth output voltage from the fourth detection electrode disposed on the Y axis of the inertial sensor  10  by the first detector  21  and then subtracts the amplified fourth output voltage from the amplified third output voltage to output the Y-axis first acceleration detection voltage M Y1  corresponding to the deformations due to the Y-axis linear motion, and adds the amplified first output voltage, the amplified second output voltage, the amplified third output voltage, and the amplified fourth output voltage by the first detector  21  to output the Z-axis first acceleration detection voltage M Z1  corresponding to the deformations due to the Z-axis linear motion of the inertial sensor  10 . 
     Then, the comparator  33  of the wake up signal generation unit  30  determines whether the second acceleration detection voltage M T =M X1 +M Y2 +M Z1  calculated by adding the first acceleration detection voltage M X1 , M Y2 , and M Z1  is larger than the predetermined reference voltage V ref  (S 33 ). 
     At step S 33 , when the second acceleration detection voltage M T =M X1 +M Y2 +M Z1  is larger than the reference voltage V ref , the wake up signal is generated (S 34 ). 
     Thereafter, by receiving the generated wake-up signal, the first detector  21  is connected to the second detector  25  by the switching unit  23  to detect and output the angular velocity detection voltage W X , W Y , and W Z  corresponding to the angular velocity of each axis of the inertial sensor  10  by the woken up second detector  25 , the phase conversion unit  40 , and the driving unit  50  (S 35 ). 
     In detail, the step S 35  shifts the first acceleration detection voltage of each axis by the predetermined phase so as to the inertial sensor  10  in the directions of each axis by the phase conversion unit  40  when the wake up signal is input to generate the driving voltage D X , D Y , and D Z  and the inversion driving voltage −D X , −D Y , and −D Z  and detects and outputs the angular velocity detection voltage W X , W Y , and W Z ) corresponding to the angular velocity of each axis due to the deformations caused by the Coriolis force and the vibrations of the corresponding axis of the inertial sensor  10  by the second detector  25  when vibrating the inertial sensor  10  in the direction of the corresponding axis by providing the driving voltage D X , D Y , and D Z  and the inversion driving voltage −D X , −D Y , and −D Z  of the corresponding axis to the corresponding driving electrode through the driving unit  50 . 
     In this case, the angular velocity detection voltage W X , W Y , and W Z  corresponding to the angular velocity of each axis outputs the Y-axis angular velocity detection voltage W Y  corresponding to the Y-axis angular velocity calculated by multiplying the X-axis first acceleration detection voltage M X2  re-detected through the first detector  21  by the Z-axis driving voltage D Z  due to the deformations caused by the Coriolis force and the vibrations of the Z axis according to the Z-axis driving voltage D Z  of the inertial sensor  10  by the Z-axis driving voltage D Z , the X-axis angular velocity detection voltage W X  corresponding to the X-axis angular velocity calculated by multiplying the Y-axis first acceleration detection voltage M Y2  re-detected through the first detector  21  by the Z-axis driving voltage D Z  due to the deformations caused by the Coriolis force and the vibrations of the Z axis according to the Z-axis driving voltage D Z  of the inertial sensor  10  by the Z-axis driving voltage D Z , and the Z-axis angular velocity detection voltage W Z  corresponding to the Z-axis angular velocity calculated by multiplying the X-axis first acceleration detection voltage M X2  re-detected through the first detector  21  by the Y-axis driving voltage D Y  due to the deformations caused by the Coriolis force and the vibrations of the Y axis according to the Y-axis driving voltage D Y  of the inertial sensor  10  by the Y-axis driving voltage D. 
     Further, the angular velocity detection voltage W X , W Y , and W Z  corresponding to the angular velocity of each axis outputs the Y-axis angular velocity detection voltage W Y  corresponding to the Y-axis angular velocity calculated by multiplying the Z-axis first acceleration detection voltage M Z2  re-detected through the first detector  21  by the Z-axis driving voltage D X  due to the deformations caused by the Coriolis force and the vibrations of the Z axis according to the X-axis driving voltage D X  of the inertial sensor  10  by the X-axis driving voltage D X , the Z-axis angular velocity detection voltage W Z  corresponding to the Z-axis angular velocity calculated by multiplying the Y-axis first acceleration detection voltage M Y2  re-detected through the first detector  21  by the X-axis driving voltage D X  due to the deformations caused by the Coriolis force and the vibrations of the X axis according to the X-axis driving voltage D X  of the inertial sensor  10  by the X-axis driving voltage D X , and the X-axis angular velocity detection voltage W X  corresponding to the X-axis angular velocity calculated by multiplying the Z-axis first acceleration detection voltage M Z2  re-detected through the first detector  21  by the Y-axis driving voltage D Y  due to the deformations caused by the Coriolis force and the vibrations of the Y axis according to the Y-axis driving voltage D Y  of the inertial sensor  10  by the Y-axis driving voltage D. 
     Thereafter, the control unit  60  may further include determining whether the angular velocity detection voltage W X , W Y , and W Z  of each axis of the inertial sensor  10  detected through the second detector  25  is detected for the predetermined time and again reconverting (not shown) the woken up second detector  25 , the phase conversion unit  40 , and the driving unit  50  to be in the sleep/standby mode when there is no the angular velocity detection voltage W X , W Y , and W Z  of each axis. 
     Meanwhile, at step S 31 , when there is no output voltage S X1 , S X2 , S Y1 , and S Y2  output from the detection electrodes (for example, the first, second, third, and fourth detection electrodes) of the X axis and the Y axis, the second detector  25 , the phase conversion unit  40 , and the driving unit  50  return into the sleep/standby mode block shown in  FIG. 3  so as to continuously the sleep/standby mode, thereby performing the following processes. 
     In addition, at step S 33 , even when the second acceleration detection voltage M T =M X1 +M Y2 +M Z1  is not larger than the reference voltage V ref , the second detector  25 , the phase conversion unit  40 , and the driving unit  50  returns to the sleep/standby mode block shown in  FIG. 3  so as to continuously the sleep/standby mode shown in  FIG. 3 , thereby performing the following processes. 
     As described above, according to the apparatus and the method for driving an inertial sensor of the preferred embodiment of the present invention, the component (for example, the first detector  21 ) for sensing the acceleration of each axis of the inertial sensor  10  are in an on state at all times and the components (for example, the second detector  25 , the phase conversion unit  40 , and the driving unit  50 ) for sensing the angular velocity of each axis of the inertial sensor  10  is in the sleep/standby mode to wake up the components for sensing the angular velocity only at the time of sensing the acceleration of the predetermined value or more, thereby preventing the unnecessary power consumption. 
     As set forth above, the preferred embodiment of the present invention can prevent the unnecessary power consumption by waking up and driving the components sensing the angular velocity in the sleep mode when the acceleration of the predetermined value or more is sensed by the components sensing the acceleration. 
     Although the embodiment of the present invention has been disclosed for illustrative purposes, it will be appreciated that an apparatus and a method for driving an inertial sensor according to the invention are not limited thereby, 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. 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.