Abstract:
The actuator comprises of two magnetic elements, four metallic wires, a lens holder located between the two magnetic elements for holding a lens, and a planar coiling device affixed on the lens holder. The lens holder further comprises of at least one fixing part whose purpose is to connect with the four metallic wires and keep the lens holder at a hanging status. The planar coiling device further comprises of two focusing coils, two tracking coils and four separated bonding pads, two bonding pads located on each of the two surfaces of the planar coiling device for respectively connecting with the four metallic wires; two of the four bonding pads electrically connect to the two focusing coils and the other two bonding pads electrically connect to the two tracking coils.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an actuator of an optical pickup head, and more particularly to an actuator of an optical pickup head with horizontal-arranged magnetic field producing apparatus and coiling device. 
       BACKGROUND OF THE INVENTION 
       [0002]    Our world lives in the age of information outburst. Most media products are put in circulation in the forms of optical disks. The optical pickup head of an optical drive responsible for reading the information from or writing information onto an optical disk thus play an important role in today&#39;s optical storage technology. 
         [0003]    Please refer to  FIG. 1  to  FIG. 3 .  FIG. 1  illustrates the overlooking view of an actuator of a conventional optical pickup head;  FIG. 2  illustrates the lateral view, while  FIG. 3  illustrates the three dimensional view. Actuator  100  of optical pickup head includes a lens holder (not shown), a magnetic field producing apparatus, a focusing coil  132  and tracking coils  134 . The lens holder, normally made of non-magnetic conducting material, is used to carry one lens (illustrated with dotted line)  110 , focusing coil  132  and tracking coils  134 . Ordinarily, the lens holder is affixed and hung over metallic wires or leaf springs. When focusing coil  132  and tracking coils  134  oscillates vertically and horizontally under control the movement also causes oscillation of lens holder and the lens  110 . Therefore, movement of the lens  110  is controlled and the light beam produced by a semiconductor laser through lens  110  can be focused at the correct position to enable the optical drive to write or read information from an optical disk. 
         [0004]    The magnetic field producing apparatus is not in contact with the lens holder, lens  110 , focusing coil  132 , and the tracking coils  134 ; it is a permanently stationary apparatus in response to the lens holder. The magnetic field producing apparatus includes a first magnet  122 , a first yoke  123 , a second magnet  124  and a second yoke  125 ; the magnetic surface of the second magnet  124  faces the magnetic surface of the first magnet  122 . The neighboring tracking coils  134  in between the first magnet  122  and the second magnet  124  are of the same polarity, i.e. they are either all N-or all S-polarity. Through the interaction between the first magnet  122  and the first yoke  123 , and the interaction between the second magnet  124  and the second yoke  125 , the magnetic field producing apparatus in between the magnets and yokes respectively produce a fixed-direction magnetic field. 
         [0005]    Focusing coil  132  is placed between the first magnet  122  and the second magnet  124 , the plane of focusing coil  132  is perpendicular to the magnetic surface of the first magnet  122  and the second magnet  124 . When electric current runs through focusing coil  132 , a first force is created by the interaction between focusing coil  132  and the above mentioned magnetic field which enables the lens holder to move along a focusing direction. 
         [0006]    The tracking coils  134  are located in between the focusing coil  132  and the first magnet  122  and in between the focusing coil  132  and the second magnet  124 ; the plane of tracking coil  134  is parallel to the magnetic surface of the first magnet  122  and the second magnet  124 . When electric current runs through tracking coils  134 , a second force is created by the interaction between tracking coil  134  and the previously mentioned magnetic field; this second force then enables the lens holder to move along a tracking direction. 
         [0007]    In a conventional actuator of optical pickup heads, in order to move the lens holder along the focusing and the tracking directions, product developing engineers need to devise a structural design for the first and second forces to be perpendicular with each other. This makes the coiling process of the focusing coil and tracking coil minute and complicated, increasing manufacturing time and production cost. For the same reason, the volume size and thickness of the conventional actuator of optical pickup head has been difficult to reduce, thereby limiting the application of optical pickup heads on small form factor optical disk drives (SFFO). 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, the present invention provides an actuator of an optical pickup head with horizontal-arranged magnetic field producing apparatus and coiling device having very thin thickness for used on small form factor optical disk drives (SFFO). 
         [0009]    The present invention provides an actuator of an optical pickup head, comprising: two magnetic elements; a plurality of metallic wires; a lens holder connected to the metallic wires for hanging the lens holder and located the lens holder between the two magnetic elements; and a planar coiling device affixed on the lens holder and the coiling device including at least one focusing coil, at least one tracking coil and a plurality of separated bonding pads for electrically connecting to the metallic wires respectively; wherein two of the four bonding pads electrically connect to the at least one focusing coil and two bonding pads electrically connect to the at least one tracking coil. 
         [0010]    The present invention further provides an actuator of an optical pickup head, comprising: a magnetic field producing apparatus including two magnetic elements; a hanging device including a plurality of electrically conducting elements; a lens holder connected to the hanging device for hanging the lens holder and located the lens holder between the two magnetic elements; and a planar coiling device affixed on the lens holder and the coiling device including at least one focusing coil, at least one tracking coil and a plurality of separated bonding pads for connecting to the electrically conducting elements respectively; wherein two of the four bonding pads electrically connect to the at least one focusing coil and two bonding pads electrically connect to the at least one tracking coil. 
         [0011]    In one embodiment, the magnetic elements are magnets and each magnet comprises a plurality of magnetic areas. 
         [0012]    In one embodiment, the planar coiling device is constructed by a print circuit board with a plurality of print circuit coils. 
         [0013]    In one embodiment, the planar coiling device is constructed by a plastic substrate with a plurality of fine pattern coils. 
         [0014]    In one embodiment, the at least one focusing coil and the at least one tracking coil are coiled into rectangular or circular shapes. 
         [0015]    In one embodiment, two bonding pads are located on each of the two surfaces of the planar coiling device. 
         [0016]    In one embodiment, the hanging device comprises a plurality of metallic wires or a plurality of leaf springs. 
         [0017]    The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  shows an overlooking view of an actuator of a conventional optical pickup head; 
           [0019]      FIG. 2  shows a lateral view of an actuator of a conventional optical pickup head; 
           [0020]      FIG. 3  shows a three-dimensional view of an actuator of a conventional optical pickup head; 
           [0021]      FIG. 4  shows an actuator of an optical pickup head according to the embodiment of the present invention; 
           [0022]      FIG. 5  shows a lateral view of the actuator of optical pickup head according to the embodiment of the present invention; 
           [0023]      FIG. 6  shows an overlooking perspective drawing of an actuator of optical pickup head according to the embodiment of the present invention; 
           [0024]      FIG. 7  shows a movement of tracking coils when first current is being conducted; and 
           [0025]      FIG. 8  shows a movement of focusing coils when second current is being conducted. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]    Please refer to  FIG. 4  illustrating an actuator of an optical pickup head according to the embodiment of the present invention. The lens holder  410  of actuator  400  holds a lens  412  and a coiling device  430  including focusing coils and the tracking coils. Further, the hanging lens holder  410  is hung by a hanging device, such as metallic wires or spring leafs. As demonstrated in  FIG. 4 , the hanging device comprising four metallic wires  440   a ,  440   b ,  440   c ,  440   d . The hanging device could further act as an electric current conducting wires that controls the focusing coils and the tracking coils. As shown in  FIG. 4 , it can be seen that two of the metallic wires are used to conduct current in and out of the focusing coils, while the other two wires are used to conduct current in and out of the tracking coils. The coiling device  430  is placed horizontally within the magnetic field producing apparatus, and a plurality of magnetic areas having different polarities are devised on the same magnetic surface of the magnetic field producing apparatus. Under such horizontal arrangement of the coiling device  430  and magnetic field producing apparatus magnets, lens holder  410  is prompted to move along the focusing and tracking directions. The actuator  400  with horizontal-arranged magnetic field producing apparatus and coiling device  430  would therefore be able to reduce the volume and thickness of an optical pickup head. Further, the horizontal arrangement in the present invention application is the plane that will be in parallel with the surface of an optical disk. 
         [0027]    Please refer to  FIGS. 5 and 6 .  FIG. 5  illustrates the lateral view of an actuator of an optical pickup head of the present invention while  FIG. 6  illustrates an overlooking view. Actuator  400  is moved for reading or writing the information on the information tracks of an optical disk  10 . Actuator  400  includes the lens holder  410 , magnetic field producing apparatus and the coiling device  430 . The design of lens holder  410  is hanging and is hung through connecting metallic wires  440   a ,  440   b ,  440   c , and  440   d.    
         [0028]    The magnetic field producing apparatus is used to produce a first magnetic field and a second magnetic field. The magnetic direction of the first magnetic field is perpendicular to the surface of the optical disk  10 ; the magnetic direction of the second magnetic field is parallel to the surface of the optical disk  10 . The magnetic field producing apparatus includes two magnetic elements such as the first magnet  422  and the second magnet  424 ; the first magnet  422  is horizontally placed above the lens holder  410  while the second magnet  424 , corresponding to the first magnet  422 , is placed horizontally below lens holder  410 . 
         [0029]    Coiling device  430  is horizontally placed and affixed on the lens holder  410 , and it is constructed by fine pattern coils on a plastic substrate or a print circuit coils on a print circuit board; thus the coiling device  430  is a planar coiling device  430  with very thin thickness. On the coiling device  430  focusing coils  432   a ,  432   b  and tracking coils  434   a ,  434   b  can be formed; focusing coils  432   a ,  432   b  and tracking coils  434   a ,  434   b  can be coiled into a rectangular or a circular shape. When a first current is conducted through tracking coils  434   a ,  434   b , a first force created by the first current interacting with the first magnetic field will move the lens holder  410  which in turn leads actuator  400  to move along the tracking direction. When a second current is conducted through focusing coils  432   a ,  432   b , a second force created by the second current interacting with the second magnetic field will move the lens holder  410  which in turn leads actuator  400  to move along the focusing direction; tracking coils  434   a ,  434   b  and focusing coils  432   a ,  432   b  will be placed on the same horizon as illustrated in  FIG. 6 . 
         [0030]    Further, two fixing parts  442  can be placed respectively on two sides of lens holder  410 ; through these two fixing parts, metallic wires  440   a ,  440   b ,  440   c ,  440   d  can go through to keep lens holder  410  at a hanging status. Since metallic wires  440   a ,  440   b ,  440   c ,  440   d  must provide for current to be conducted in and out of the focusing coils  432   a ,  432   b  and the tracking coils  440   c ,  440   d , the top and bottom planes of coiling device  430  can each form two bonding pads respectively for a total of four bonding pads  446   a ,  446   b ,  446   c ,  446   d , to be connected to fixing part  442 , respectively by the metallic wires  440   a ,  440   b ,  440   c ,  440   d . As illustrated in the present invention, coiling device  430  comprises of two focusing coils  432   a ,  432   b , and two tracking coils  434   a ,  434   b . The first current can run through metallic wire  440   a , bonding pad  446   a , into first tracking coil  434   a , and out of first tracking coil  434   a , into second tracking coil  434   b , out of second coil  434   b  to then run through bonding pad  446   b  and metallic wire  440   b  and finally out of actuator  100 . By the same logic, the second current can run through metallic wire  440   c , bonding pad  446   c , into first focusing coil  432   a , then out of first focusing coil  432   a  to run into second focusing coil  432   b ; after second current runs out of second focusing coil  432   b  it can then run through bonding pad  446   d  and metallic wire  440   d  and finally out of actuator  100 . As shown in  FIG. 6 , since bonding pads  446   c ,  446   d  are positioned directly below bonding pads  446   a ,  446   b , the dotted line of  FIG. 6  represents the electric connection to bonding pads  446   c ,  446   d , while the solid line represents electric connection to bonding pads  446   a ,  446   b.    
         [0031]    In order for lens holder  410  carrying lens  412  to move along focusing or tracking directions after currents are respectively conducted through focusing coils  432   a ,  432   b  and tracking coils  434   a ,  434   b , the horizontal arrangement of the first and second magnets  422 ,  424  above and below lens holder  410  will be devised to have a plurality of magnetic areas having different polarities in response to the corresponding positions of the focusing coils  432   a ,  432   b  and tracking coils  434   a ,  434   b.    
         [0032]    Please refer to  FIG. 7 , illustration of the first current being conducted through the tracking coils. When the design of coiling device  430  is as illustrated in  FIG. 6 , magnetic areas on the first magnet  422  can be divided into first magnetic area  442 ( 1 ), second magnetic area  422 ( 2 ), third magnetic area  422 ( 3 ), forth magnetic area  422 ( 4 ) and fifth magnetic area  422 ( 5 ). Various magnetic areas in the second magnet are first magnetic area  424 ( 1 ), second magnetic area  424 ( 2 ), third magnetic area  424  ( 3 ), forth magnetic area  424  ( 4 ) and fifth magnetic area  424  ( 5 ). The various magnetic areas of first magnet  422  and second magnet  424  are designed in response to the corresponding positions of the focusing coils  432   a ,  432   b  and tracking coils  434   a ,  434   b  of coiling device  430 . 
         [0033]    A first polarity, such as S, is assigned to the magnetic areas neighboring to coiling device  430 , of first magnetic area  422 ( 1 ), third magnetic area  422 ( 3 ), and fifth magnetic area  422 ( 5 ) of first magnet  422  and first magnetic area  424 ( 1 ) and fifth magnetic area  424 ( 5 ) of second magnet  424 . A second polarity, for instance N, is then assigned to the other magnetic areas neighboring to coiling device  430  including: second magnetic area  422 ( 2 ) and forth magnetic area  422 ( 4 ) of the first magnet  422 , and second magnetic area  424 ( 2 ), third magnetic area  424 ( 3 ) and forth magnetic area  424  ( 4 ) of the second magnet. 
         [0034]    By assigning, magnetic areas neighboring to coiling device  430 , polarity of S on the third magnetic area  422 ( 3 ) of first magnet  422  and polarity of N on the third magnetic area  424 ( 3 ) of second magnet  424 , the magnets can create a first magnetic field B 1 ; the direction of such magnetic field B 1  is perpendicular to the plane of coiling device  430  and the surface of the optical disk. 
         [0035]    If first current I 1  is conducted through tracking coils  434   a ,  434   b , the first magnetic field will interact with first magnetic field B 1  to form a first force F 1 . Since hanging apparatus  440  is keeping lens holder  410  at a hanging status, such first force F 1  can enable lens holder  410  to move along the tracking direction. 
         [0036]    Please refer to  FIG. 8 , illustration of second current being conducted through focusing coils. By the same logic, by assigning polarity of S to magnetic areas neighboring to coiling device  430  on first magnetic area  422 ( 1 ), fifth magnetic area  422 ( 5 ) of first magnet and first magnetic area  424 ( 1 ), fifth magnetic area  424 ( 5 ) of the second magnet  424 , and assigning polarity of N to magnetic areas neighboring to coiling device  430  on second magnetic area  422 ( 2 ), forth magnetic area  422 ( 4 ) of the first magnet  422 , and second magnetic area  424 ( 2 ) and forth magnetic area  424 ( 4 ) of the second magnet  424 , the magnets form a second magnetic field B 2 ; the direction of magnetic field B 2  is parallel to the plane of the coiling device  430  and the surface of the optical disk. 
         [0037]    When second current  12  is conducted through focusing coils  434   a ,  434   b , under the influence of second magnetic field B 2 , actuator  400  will produce a second force F 2  according to second current  12 ; second force F 2  then prompts the lens holder  410  to move along focusing direction. 
         [0038]    The perpendicular first and second forces will prompt lens holder to move along tracking or focusing direction in order to read or write information. The design of lens holder is not limited to the description of presently illustrated embodiment. The same effect can still be reached with an altered design of lens holder. 
         [0039]    The present invention is intended to cover various modifications and similar arrangements included to within the spirit and scope of the appended claims, which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.