Abstract:
The present invention relates to a tray locking device for optical disc drive, which uses a driving element and a memory metal having different lengths at different temperature conditions to control the movement of the driving element to drive a locking mechanism. Accordingly, it attains the objects of simplifying its structure and saving assembling space, and avoids the breakage of the memory metal attributed to shocking force during drop test.

Description:
[0001]     This Non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 094115921 filed in Taiwan, Republic of China on May 17, 2005, the entire contents of which are thereby incorporated by reference.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a tray locking device for optical disc drive, particular to a tray locking device for optical disc drive which is driven by a memory metal.  
       BACKGROUND OF THE INVENTION  
       [0003]     The tray locking device used in the slim type optical disc drive, according to its driving manner, is classified into a solenoid driving type and direct current (DC) motor driving type.  
         [0004]     The solenoid driving type tray locking device mainly uses a magnetic attraction generated by the solenoid to disengage a hook from a lock pin and allow the tray locking in the optical disc drive. However, in a drop test for optical disc drive, the magnetic attraction is not enough to hold the hook in engaging with the lock pin, therefore the tray will slide out from the optical disc drive unexpectedly.  
         [0005]     To resolve this problem, a DC motor driving type tray locking device is developed. To control the starting or stopping of the motor, in relevant designs, most of the DC motor driving type tray locking device use a switch to control the position of the hook. However, since the transmission of stopping signal from the switch might delay, the stop time of the motor is also late and the hook stops at an inappropriate position. In this regards, it might result in the locking device jamming.  
         [0006]     Moreover, the solenoid and the DC motor driving type locking devices both include so many mechanical members or the hook driving manner is complex, it will occupy a lot of device space and is not easily to assemble so the assembly cost is increased. There needs further improvements to simplify the structure for attaining thinning of the device and cost down.  
         [0007]     In the end, use of a memory metal to control the hook engaging with or disengaged from the lock pin has been developed. Such a typical design is shown in  FIGS. 1 and 2 .  FIG. 1  is a schematic view showing a structure of conventional tray locking device, and  FIG. 2  is a partial enlarging view of the tray locking device shown in  FIG. 1 . As shown in the Figures, the locking device is provided on a tray T and engages with a lock pin B 1  provided on the inside wall of a housing (not shown in the Figures). Also, by using the property of the memory metal line L 1  that its length varies with different temperatures, one end of a hook T 1  is driven to allow the hook T 1  spinning around a spinning axis T 2  and the hook T 1  is in turn released from the lock pin B 1  to allow the tray Y carrying out of the optical disc drive.  
         [0008]     However, although the use of memory metal line to control the locking device simplifies the constituting members and effectively drive the hook to release from the lock pin, but in the drop test for optical disc drive, the memory metal line will be broken down due to the dropping force. Thus it could not pass the drop test for optical disc drive.  
         [0009]     Accordingly, the object of the present invention resides in a tray locking device for optical disc drive which has a simply structure and could withstand the dropping force generated in the drop test and achieve the purpose of cost down.  
       SUMMARY OF THE INVENTION  
       [0010]     The object of the present invention relates to a tray locking device for an optical disc drive which has a simply structure and thus saves its space occupied in the drive. The present tray locking device for optical disc drive resolves the problem of breaking of memory metal during the drop test for optical disc drive.  
         [0011]     To achieve the above object, the present invention provides a tray locking device for optical disc drive, which includes: 
        a lock pin;     a locking mechanism having a hooking part, the hooking part shifts between a first position and a second position, and the hooking part is engaged with the lock pin when it is at the first position and the hooking part is released from the lock pin when it is at the second position;     a driving element which shifts between a third position and a fourth position; and     a memory metal connected with the driving element, wherein the memory metal has a first and a second lengths at different temperature conditions;     wherein the driving element is at the third position and the hooking part is at the first position when the memory metal has the first length; and     the driving element is at the fourth position and said hooking part is at the second position when the memory metal has the second length.        
 
         [0018]     According to the embodiment of the present tray locking device, it further includes an elastic member which is connected with the hooking part and the tray. The elastic member provides elasticity for allowing the hooking part shifting from the second position back to the first position.  
         [0019]     According to the embodiment of the present tray locking device, when the driving element is at the third position, it keeps a distance from the locking mechanism. Thereby, when the optical disc drive including the present tray locking device is subjected to the drop test, the dropping force generated in the test would not transfer to the memory metal through the driving element. As a result, the memory metal would not be broken down in the test.  
         [0020]     The optical disc drive to be installed with the present tray locking device includes a tray on which optical modules such as a turntable, pick up unit, etc., are provided and a housing for accommodating the tray. The present tray locking device is used for controlling the lock/unlock of the tray in the housing. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0021]     The present invention is illustrated more detail by reference to the accompanying drawings, wherein:  
         [0022]      FIG. 1  is a schematic view showing a structure of conventional tray locking device.  
         [0023]      FIG. 2  is a partial enlarging view of the tray locking device shown in  FIG. 1 .  
         [0024]      FIG. 3  is a schematic view showing an optical disc drive including the tray locking device of the present invention, in which the tray is carried out from the housing.  
         [0025]      FIG. 4  is a schematic view showing a structure of one embodiment of the tray locking device of the present invention.  
         [0026]      FIG. 5  is a partial enlarging view of the tray locking device shown in  FIG. 4 , in which the memory metal has the first length.  
         [0027]      FIG. 6  is a partial enlarging view of the tray locking device shown in  FIG. 4 , in which the memory metal has the second length and the tray is carrying out from the housing.  
         [0028]      FIG. 7  is a partial enlarging view of the tray locking device shown in  FIG. 4 , in which the tray is carrying into the housing. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]     The present invention is illustrated in more detail by reference the following preferred embodiments which are only used for illustration without limiting the scope of the present invention.  
         [0030]     The present invention will be illustrated in more detail by reference to an embodiment in which the present tray locking mechanism is provided on a tray and a lock pin is provided on the inner wall of a housing. However, the present invention is not limited to the mentioned above. This is, the tray locking mechanism could be provided on the inner wall of a housing and a lock pin could be provided on a tray, as long as the tray locking mechanism is effectively engaged with the lock pin.  
         [0031]     Please refer to  FIG. 3 .  FIG. 3  is a schematic view showing an optical disc drive including the tray locking device of the present invention, in which the tray is carried out from the housing.  
         [0032]     The present invention relates to a tray locking device for an optical disc drive in which the optical disc drive includes a housing B and an optical disc tray T on which a turntable and a pick up unit are provided (not shown in the Figures). The present tray locking device is used for controlling the lock/unlock of the tray T in the housing B. The tray locking device includes a lock pin B 1 , a locking mechanism  10 , a driving element  20 , and a memory metal  30 , in which the lock pin B 1  is provided on the inner wall of the housing B (as shown in  FIG. 3 ) and the locking mechanism  10  is provided on the tray T corresponding to the lock pin B 1 .  
         [0033]     Please also refer to FIGS.  4  to  6 .  FIG. 4  is a schematic view showing a structure of one embodiment of the tray locking device of the present invention;  FIG. 5  is a partial enlarging view of the tray locking device shown in  FIG. 4 , in which the memory metal has the first length; and  FIG. 6  is a partial enlarging view of the tray locking device shown in  FIG. 4 , in which the memory metal has the second length and the tray is carrying out from the housing.  
         [0034]     According to the present tray locking device, the locking mechanism  10  includes a hook  11  having a hooking part  111  for engaging with or releasing from the lock pin B 1 . The hook  11  can rotate on the tray around the spinning axis  101  to allow the hooking part  111  being shifted between the first position and the second position. When the locking part  111  is at the first position, the locking part  111  is engaged with the lock pin B 1 , as shown in  FIG. 5 . When the locking-part  111  is at the second position, the locking part  111  is released from the lock pin B 1 , as shown in  FIG. 6 .  
         [0035]     However, the above locking mechanism could also be a linker mechanism consisting of a plural of connecting rods or any connecting mechanism, as long as the mechanism has a hooking part to engage with/release from the lock pin and can shift between the first and the second positions.  
         [0036]     According to the present tray locking device, the driving element  20  is pivotally provided on the tray T and its one end  202  is connected with a memory metal  30  and the other end  201  is used to pull the locking mechanism  10 . The driving element  20  can shift between the third position and the fourth position, as shown in  FIGS. 5 and 6 , to allow the end  202  pushing on or leaving the locking mechanism  10  to further control the engagement (disengagement) of the hooking part with (out from) the lock pin. In this embodiment, when the memory metal  30  has the first length, the driving element  20  is at the third position and the hooking part  111  is at the first position to allow the hooking part being engaged with the lock pin B 1 , as shown in  FIG. 5 . And when the memory metal  30  has the second length, the driving element  20  is driven to the fourth position and allows the end  201  driving the locking mechanism  10  to allow the hooking part  111  being moved to the second position and being released from the lock pin B, as shown in  FIG. 6 . Moreover, when the driving element  20  is at the third position and the hooking part  111  is at the first position, the end  201  keeps a distance G from the locking mechanism  10  to avoid the dropping force generated in the drop test to transfer to the memory metal  30  through the driving element  20 . Thus the breakage of the memory metal would not occur during the test.  
         [0037]     According to the present tray locking device, the memory metal  30  is provided on the tray by connecting parts  31 . By using the property of the memory metal that it will shorten when heating, the memory metal  30  has the first length without heating and has the second length when electric power is applied to the connecting parts  31  to generate heat. When the memory metal  30  has the first length, the driving element  20  is at the third position and the hooking part  111  is at the first position. At this time, the tray locking device is in a lock state and there is a distance G between the driving element  20  and the locking mechanism  10 . When the memory metal  30  has the second length, the driving element  20  is at the fourth position to allow the end  202  pushing on the locking mechanism  10  and allow the hooking part  111  moving to the second position. At this time, the tray locking device is in an unlock state and thus the tray could be carried out from the drive.  
         [0038]     According to the present tray locking device, it further includes an elastic member  12  which is provided on the tray T and connected with said locking mechanism  10 . The elastic member  12  provides elasticity for allowing the hook  11  shifting from the second position back to the first position.  
         [0039]     According to the present tray locking device, when the tray T is to be carried out from the drive, electric power is applied to the connecting parts  31  of the memory metal  30  to allow the metal  30  changing its length from the first length to the second length. Thus the memory metal  30  pulls the driving element  20  moving from the third position to the fourth position, as shown in  FIG. 6 . In this time, the end  201  pushes the locking mechanism  10  to allow its hooking part  111  moving from the first position to the second position. Thus the hooking part  111  is released from the lock pin B 1  and the tray T is in turn carried out from the drive.  
         [0040]     Please refer to  FIG. 7 .  FIG. 7  is a partial enlarging view of the tray locking device shown in  FIG. 4 , in which the tray is carrying into the housing.  
         [0041]     When the tray T is to be carried into the drive, the lock pin B 1  is against the tilt edge  113  of the hooking part  111  and in turn pushes hooking part  111  to allow it moving from the first position to the second position and carrying the tray T into the drive. When the lock pin B 1  leaves the tilt edge  113 , the elastic member  12  provides elasticity for allowing the hooking part  111  shifting from the second position back to the first position and engaging with the lock pin B 1 . Thus the tray T is in a lock state in the drive.  
         [0042]     According to the present tray locking device, a through hole B 2  is provided on the tray near the driving element  20 . The driving element  20  could be forcedly moved from the third position to the fourth position via the through hole B 2  by using tool to push the hooking part  111  moving from the first position to the second position and releasing from the lock pin B 1 . Therefore if in emergency, user can forcedly carry the tray out from the drive.  
         [0043]     According to the present tray locking device, the control of the engagement/disengagement of the locking mechanism from the lock pin is directly driven by the memory metal through the driving element. It simplifies the structure of the tray locking device and saves its assembly space, and it also effectively avoids the breakage of the memory metal during the drop test.  
         [0044]     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.