Patent Publication Number: US-2012033093-A1

Title: Image stabilizer control device

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to image stabilizer control devices. 
     2. Description of Related Art 
     An imaging module typically includes an image sensor for converting light into electrical signals. The electrical signals can be processed to form images. If the imaging module experiences vibration or movement during image capturing, the image sensor is likely to form blurred images. Therefore, an image stabilizer is employed to compensate for the vibration or movement of the image sensor. However, compensation precision of the image stabilizer is unsatisfactory. 
     Therefore, an image stabilizer control device, which can overcome the above-mentioned problems, is needed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a functional block diagram of an image stabilizer control device, according to an exemplary embodiment. 
         FIG. 2  is a schematic view of the image stabilizer control device of  FIG. 1  used in an exemplary imaging module, showing the imaging module in a still state. 
         FIG. 3  is similar to  FIG. 2 , but showing the imaging module in a shaked state. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , an image stabilizer control device  100 , according to an exemplary embodiment, includes a biaxial gyroscope  11 , a processing unit  12 , and an actuator unit  13 . The control device  100  is used in an imaging module  200 . The imaging module  200  includes a base  201 , an image sensor  202 , and a lens module  203 . The image sensor  202  and the lens module  203  are mounted to the base  201 . The image sensor  202  is located at the image side of the lens module  203 . The lens module  203  has an optical axis O, which is the optical axis of the imaging module  200 . 
     The biaxial gyroscope  11  is electrically connected to the processing unit  12  and is configured for sensing movement of the imaging module  200  caused by shake and detecting a first angular velocity in two reference planes. The two reference planes are perpendicular to each other. When the imaging module  200  is in a still state (see  FIG. 2 ), the two reference planes are an X-Z plane and a Y-Z plane both parallel to the optical axis O in an X-Y-Z coordinate system. The Z axis of the X-Y-Z coordinate system is parallel to the optical axis O, and the X, Y axes are perpendicular to the optical axis O when the imaging module  200  is in the still state. When the imaging module  200  experiences movement, such as from vibration/shake, the biaxial gyroscope  11  detects a first deviation angular velocity along a first direction, and a second deviation angular velocity along a second direction. That is, the first angular velocity includes the first deviation angular velocity and the second deviation angular velocity. The first direction is a direction of the imaging module  200  rotating about the Y axis in the X-Z plane, i.e., a yaw direction. The second direction is a direction of the imaging module  200  rotating about the X axis in the Y-Z plane, i.e., a pitch direction. 
     The processing unit  12  is configured for generating a first driving signal in response to the first angular velocity. 
     In this embodiment, the processing unit  12  includes an integrator  121 , a band-pass filter  122 , an operational amplifier  123 , a compensator  124 , and a driving chip  125 . The integrator  121  is electrically connected to the biaxial gyroscope  11  and the band-pass filter  122 . The operational amplifier  123  is electrically connected to the band-pass filter  122  and the driving chip  125 . The compensator  124  is electrically connected to the operational amplifier  123  and the driving chip  125 . The driving chip  125  includes a pulse width modulation power driving chip. 
     The integrator  121  is a double integrator. The first angular velocity is processed by the integrator  121 , the band-pass filter  122 , and the operational amplifier  123  to be converted into a first angle. The first angle includes a first deviation angle and a second deviation angle. The driving chip  125  generates the first driving signal in response to the first angle. 
     The actuator unit  13  is electrically connected to the driving chip  125  of the processing unit  12  and is configured for moving the imaging module  200  to compensate the movement of the imaging module  200  in response to the first driving signal. 
     The actuator unit  13  includes a first actuator  131  and a second actuator  132 . The first actuator  131  is configured for moving the imaging module  200  in one of the two reference planes, such as the X-Z plane. The second actuator  132  is configured for moving the imaging module  200  in the other one of the two reference planes, such as the Y-Z plane. The first and second actuators  131 ,  132  may be piezoelectric actuators, surface acoustic wave actuators, or other suitable actuators. 
     The biaxial gyroscope  11  is configured for detecting a second angular velocity in the two reference planes upon completing the movement compensation associated with the first driving signal. The processing unit  12  is configured for converting the second angular velocity into a second angle and comparing the second angle with a predetermine angle range and generating a second driving signal in response to the comparison result. Specifically, the compensator  124  compares the second angle with a predetermine angle range and generates the second driving signal in response to the comparison result. The actuator unit  13  moves the imaging module  200  in response to the second driving signal. The predetermined angle range includes a first angle range along the first direction and a second angle range along the second direction. The first angle range is defined as a range of an included angle between the Z axis (also indicated as the dashed line L in  FIG. 3 ) and the optical axis O along the first direction. For example, the first angle range may be [0, 0.05] degrees. The second angle range is defined as a range of an included angle between the Z axis and the optical axis O along the second direction. For example, the second angle range may be [0, 0.05] degrees. 
     Referring to  FIG. 3 , when the imaging module  200  experiences vibration/shake, the optical axis O of the lens module  203  is deviated counterclockwise from its original position L by an angle θ about the Y axis in the X-Z plane. The optical axis O at its original position L is parallel to the Z axis. Under this circumstance, the biaxial gyroscope  11  detects the first angular velocity of the imaging module  200 . The processing unit  12  converts the first angular velocity into a first angle θ1 and controls the actuator unit  13  to move the imaging module  200  to rotate clockwise about the Y axis by the first angle θ1. 
     When the above movement compensation of the imaging module  200  associated with the first driving signal is completed, the biaxial gyroscope  11  further detects a second angular velocity of the imaging module  200 . The processing unit  12  converts the second angular velocity into a second angle θ2 and compares the second angle θ2 with the predetermined angle range [0, 0.05] degrees. If 0°≦θ2≦0.05°, the processing unit  12  generates a null signal to idle the actuator unit  13 . If θ2&gt;0.05°, the processing unit  12  generates a driving signal to activate the actuator unit  13  to move the imaging module  200  until the second angle θ2 is within the predetermined angle range [0, 0.05] degrees. Therefore, movement compensation of the imaging module  200  can be satisfactory. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.