Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a heat dissipator for an optical writing and/or reproducing apparatus, and more particularly, the present invention relates to a heat dissipator for an optical writing and/or reproducing apparatus, which is constructed to properly dissipate heat generated in a heat generating element, especially, a drive IC (integrated circuit) while the optical writing and/or reproducing apparatus is driven.  
           [0003]    2. Description of the Related Art  
           [0004]    Generally, in an optical writing and/or reproducing apparatus such as a disk drive, a great amount of heat is generated during operation. In an optical writing and/or reproducing apparatus, heat generating parts include a loading motor for producing power needed to load and eject an optical disk, a spindle motor for rotating the optical disk, an optical pick-up for writing and/or reproducing data on and/or from the optical disk, a step motor for driving the optical pick-up, and elements installed on a circuit board for controlling operation of the optical writing and/or reproducing apparatus.  
           [0005]    If generated heat is not properly dissipated out of the optical writing and/or reproducing apparatus, not only the corresponding heat generating source but also surrounding parts can be adversely affected by the heat, and thereby, an operational error can be caused in the optical writing and/or reproducing apparatus.  
           [0006]    Specifically, among the elements installed on the circuit board for controlling operation of the optical writing and/or reproducing apparatus, a drive IC for controlling driving of the motors generates a substantial amount of heat when compared to the other elements.  
           [0007]    [0007]FIG. 1 is a cross-sectional view illustrating a conventional heat dissipator for an optical writing and/or reproducing apparatus.  
           [0008]    Referring to FIG. 1, an optical writing and/or reproducing apparatus includes a main base  30 , and a circuit board  40  positioned below the main base  30 . Elements for controlling operation of the optical writing and/or reproducing apparatus are installed on the circuit board  40 . A spindle motor, a loading motor and a step motor (not shown) are installed on the main base  30 .  
           [0009]    Among the elements installed on the circuit board  40 , since a drive IC  42  continuously controls driving of the motors, it consumes a large amount of power and thereby generates a substantial amount of heat when compared to the other elements. For this reason, the drive IC  42  is installed on a lower surface  40   b  of the circuit board  40  so as not to adversely influence, by heat, surrounding elements including an RF (radio frequency) IC and a DSP (digital signal processor) IC which are installed on an upper surface  40   a  of the circuit board  40 . At this time, the drive IC  40  is installed in a manner such that outer leads  43  externally formed thereon are bonded to the lower surface  40   b  of the circuit board  40 .  
           [0010]    Hereafter, the conventional heat dissipator for dissipating heat generated in the drive IC  42  will be described in detail.  
           [0011]    The heat dissipator includes a lower cabinet  51   b  which is positioned to face the lower surface  40   b  of the circuit board  40  and a heat dissipating conduction member  54  which is interposed between the lower cabinet  51   b  and a molding section  42   a  of the drive IC  42 . The lower cabinet  51   b  delimits an outer contour of the optical writing and/or reproducing apparatus and is made of a metallic material. The heat conduction member  54  functions to dissipate or conduct the heat generated in the drive IC  42 . Over a region where the lower cabinet  51   b  faces the molding section  42   a  of the drive IC  42 , the lower cabinet  51   b  is formed with an upward protrusion  51   c  which projects toward the drive IC  42  to allow the heat dissipating conduction member  54  to be brought into close contact with the molding section  42   a  of the drive IC  42 .  
           [0012]    At this time, the heat conduction member  54  is not brought into contact with the outer leads  43  which serve to connect the drive IC  42  to the circuit board  40 .  
           [0013]    Concretely speaking, between the drive IC  42  installed on the lower surface  40   b  of the circuit board  40  and the lower cabinet  51   b  facing the drive IC  42 , there is interposed the heat conduction member  54  in a manner such that it is brought into close contact with the molding section  42 a of the drive IC  42 . As a consequence, heat generated in the molding section  42   a  of the drive IC  42  is transmitted through the heat conduction member  54  to the lower cabinet  51   b  to be dissipated to the outside.  
           [0014]    However, the conventional heat dissipator constructed as mentioned above suffers from defects as described below.  
           [0015]    While heat generated inside the drive IC  42  is first conducted to a molding material, that is, the molding section  42   a  serving as an encapsulant, and then transmitted to the lower cabinet  51   b , in actual fact, since a considerable portion of the heat generated inside the drive IC  42  is conducted to the outer leads  43  made of a metallic material, the outer leads  43  have a higher temperature than the molding material. Resultingly, as heat of the outer leads  43  is transmitted to a circuit pattern formed on the circuit board  40 , the circuit pattern is likely to be thermally damaged.  
           [0016]    Also, because the heat conduction member  54  is installed over the region which faces only a lower surface of the molding section  42   a  of the drive IC  42 , heat of side surfaces of the drive IC  42  and heat of the outer leads  43  cannot be properly conducted to the heat dissipating conduction member  54 . Therefore, heat as a whole, generated in the entire drive IC  42 , cannot be properly transmitted to the lower cabinet  51   b.    
           [0017]    The reason for this is that only heat of the lower surface of the molding section  42   a  of the drive IC  42  is conducted to the heat conduction member  54  to be dissipated to the outside, and heat of the side surfaces of the drive IC  42  and heat of the outer leads  43  are dissipated to the outside only by convection through air.  
         SUMMARY OF THE INVENTION  
         [0018]    Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a heat dissipator for an optical writing and/or reproducing apparatus, which is constructed to properly dissipate heat generated in the optical writing and/or reproducing apparatus, thereby improving operational reliability of the optical writing and/or reproducing apparatus.  
           [0019]    According to one aspect of the present invention, there is provided a heat dissipator for an optical writing and/or reproducing apparatus, comprising: a main base having mounted thereto a plurality of parts including at least one motor for optical writing and/or reproduction; a circuit board positioned below the main base and having installed thereon elements for controlling the parts; a heat generating element formed with a plurality of leads which are connected to a circuit pattern of the circuit board; a heat conduction member brought into contact with at least the leads, for receiving heat generated in the heat generating element; and a cabinet brought into contact with the heat conduction member and formed with an element accommodating section and/or a pair of protrusions which are shaped to be functionally associated with an outer surface of the heat generating element to ensure that the heat conduction member is brought into close contact with the leads of the heat generating element.  
           [0020]    According to another aspect of the present invention, there is provided a heat dissipator for an optical writing and/or reproducing apparatus, comprising: a heat generating element installed on a circuit board and having a molding section which is formed with a plurality of leads connected to a circuit pattern of the circuit board; a cabinet formed with a pair of protrusions which project toward the heat generating element to allow a portion of heat generated in the heat generating element, which portion is conducted to the leads, to be dissipated to the outside; and a heat conduction member interposed between the cabinet and the heat generating element and brought into contact with at least the leads and/or the pair of projections.  
           [0021]    According to still another aspect of the present invention, there is provided a heat dissipating structure adapted for dissipating heat generated in an optical writing and/or reproducing apparatus, comprising: a heat generating element having a molding section which is formed with a plurality of leads; a cabinet formed with an element accommodating section for accommodating the heat generating element and a pair of protrusions which delimit the element accommodating section; and a heat conduction member interposed between the heat generating element and the cabinet, for being brought into contact with the leads and the molding section and at the same time the element accommodating section and the pair of protrusions, whereby heat of the leads is transmitted to the protrusions to enhance a heat dissipation efficiency.  
           [0022]    As described above, in the heat dissipator for an optical writing and/or reproducing apparatus according to the present invention, an element accommodating section is formed on a lower cabinet in a manner such that it is functionally associated with outer surfaces and outer leads of a heat generating element, and a heat conduction member is interposed between the element accommodating section and the heat generating element.  
           [0023]    Hence, according to the present invention, advantages are provided in that, since heat is transmitted from the outer surfaces, that is, a lower surface and both side surfaces and the outer leads of the heat generating element to the heat conduction member, and dissipated through the lower cabinet to the outside, heat as a whole, generated in the heat generating element, can be properly dissipated to the outside. Also, because performance degradation of the heat generating element and surrounding parts due to overheating is prevented, operational reliability of the optical writing and/or reproducing apparatus can be improved.  
           [0024]    Further, in the present invention, due to the fact that a size of the heat dissipating member is increased to be able to cover the entire drive IC including the outer leads, a heat dissipation efficiency is enhanced. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which:  
         [0026]    [0026]FIG. 1 is a cross-sectional view illustrating a conventional heat dissipator for an optical writing and/or reproducing apparatus;  
         [0027]    [0027]FIG. 2 is an exploded perspective view illustrating an optical writing and/or reproducing apparatus in which a heat dissipator in accordance with an embodiment of the present invention is used; and FIG. 3 is a cross-sectional view illustrating the heat dissipator according to the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0028]    Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts.  
         [0029]    [0029]FIG. 2 is an exploded perspective view illustrating an optical writing and/or reproducing apparatus in which a heat dissipator in accordance with an embodiment of the present invention is used. In the present invention, the parts that correspond to those of FIG. 1 will be designated by the same reference numerals.  
         [0030]    Describing in detail, with reference to FIG. 2, a construction of an optical writing and/or reproducing apparatus which adopts a heat dissipator in accordance with an embodiment of the present invention, the optical writing and/or reproducing apparatus includes a pick-up base (not shown) serving as a frame. A spindle motor for rotating an optical disk and an optical pick-up for radiating light to write and/or reproduce data on and/or from the optical disk are installed on the pick-up base. The optical writing and/or reproducing apparatus further includes a main base  30 , a circuit board  40 , a drive IC  42 , a plurality of outer leads  43 , upper and lower cabinets  51   a  and  51   b , and a heat conduction member  54   55 . A tray  34  for loading and ejecting the optical disk into and from the optical writing and/or reproducing apparatus is arranged on the main base  30 . The circuit board  40  is positioned below the main base  30 , and a variety of elements for driving the spindle motor, the optical pick-up, etc. are installed on the circuit board  40 . The drive IC  42  is installed on a lower surface of the circuit board  40  to face an upper surface of the lower cabinet  51   b . The plurality of outer leads  43  project out of both side surfaces of the drive IC  42  and are bonded to the circuit board  40  by soldering. The upper and lower cabinets  51   a  and  51   b  which constitute a cover  50  delimit an outer contour of the optical writing and/or reproducing apparatus and are made of a metallic material. The heat conduction member  54   55  functions to transmit heat generated in the drive IC  42  to the lower cabinet  51   b  thereby to dissipate the heat to the outside.  
         [0031]    Describing in further detail the construction of the optical writing and/or reproducing apparatus which adopts the heat dissipator in accordance with the embodiment of the present invention, an upper surface  35  of the tray  34  serves as a disk seating surface on which the optical disk is seated upon being loaded and ejected. A clamp  36  is disposed above the tray  34  to clamp the optical disk to a turntable (not shown) provided to the spindle motor.  
         [0032]    A connection socket  45  for permitting connection of the optical writing and/or reproducing element to another unit is installed at one end of the circuit board  40 . The upper cabinet  51   a  defines an upper surface and both side surfaces of the optical writing and/or reproducing apparatus, and the lower cabinet  51   b  defines a lower surface of the optical writing and/or reproducing apparatus. However, it is to be readily understood that the present invention is not limited to such a structure, and the lower cabinet  51   b  can define a lower surface and both side surfaces of the optical writing and/or reproducing apparatus.  
         [0033]    Generally, a rear surface of the optical writing and/or reproducing apparatus is defined by the main base  30 , and a front surface is defined by a separate front plate (not shown).  
         [0034]    According to the present invention, over a region where the lower cabinet  51   b  faces the drive IC  42 , the lower cabinet  51   b  is formed with an element accommodating section  52 . The element accommodating section  52  defines a space which can accommodate therein the entire drive IC  42 . The element accommodating section  52  has a size which is larger than a width of the drive IC  42 . The element accommodating section  52  is delimited by a pair of protrusions  53  which project toward the circuit board  40  at left and right sides of the element accommodating section  52 . The pair of protrusions  53  are formed in a manner such that they face the outer leads  43  of the drive IC  42 . In the illustrated embodiment, the drive IC  42  has a body which possesses a parallelepiped-shaped configuration, and the plurality of outer leads  43  which project outward from both side surfaces of the body. At this time, a lower surface and both side surfaces of the body of the drive IC  42  and the outer leads  43  projecting out of both side surfaces of the drive IC  42  are functionally associated with the upper surface of the lower cabinet  51   b.    
         [0035]    The element accommodating section  52 , which is associated with the lower surface of the body of the drive IC  42 , is formed to have the same height as a remaining portion of the lower cabinet  51   b . And, the pair of protrusions  53 , which are associated with the outer leads  43 , project toward the circuit board  40  to extend upward beyond the lower surface of the body of the drive IC  42 .  
         [0036]    The heat conduction member  55  is made of soft silicon such as GAP PAD™ manufactured by BERGQUIST or Raychem™ manufactured by Tyco.  
         [0037]    [0037]FIG. 3 is a cross-sectional view illustrating the heat dissipator according to the present invention.  
         [0038]    The construction of the heat dissipator according to the present invention will be described below in further detail with reference to FIG. 3.  
         [0039]    The heat conduction member  54   55  is attached to the drive IC  42  which is installed on the lower surface of the circuit board  40 . The heat conduction member  54   55  is made of a soft material and therefore can be freely deformed. A size of the heat conduction member  54   55  is determined in a manner such that it can be brought into sufficient contact with the lower surface and the outer leads  43  of the drive IC  42 . Then, by assembling the lower cabinet  51   b  with respect to the heat conduction member  54   55 , the body of the drive IC  42  is accommodated in the element accommodating section  52 , and the pair of protrusions  53  bias the heat conduction member  54   55  to be brought into close contact with the outer leads  43 .  
         [0040]    Hereafter, working effects of the heat dissipator for an optical writing and/or reproducing apparatus according to the present invention, constructed as mentioned above, will be described in detail.  
         [0041]    While the optical writing and/or reproducing apparatus is operated, heat is generated in a number of parts. The generated heat should be properly dissipated to the outside to prevent the corresponding heat generating source and surrounding parts to be adversely affected by the heat. In the optical writing and/or reproducing apparatus, heat generating parts include the optical pick-up, the spindle motor, a step motor, and the variety of elements including the drive IC  42 .  
         [0042]    The present invention is focused on dissipation of heat generated in the variety of elements including the drive IC  42 . Description of the present embodiment will be given mainly in relation with the drive IC  42 . While the optical disk is driven, a considerable amount of heat is generated in the drive IC  42  installed on the circuit board  40 . The generated heat is partially dissipated to the outside through the lower surface and both side surfaces of the drive IC  42  and is partially conducted to the outer leads  43  made of a metallic material.  
         [0043]    The heat conduction member  55 , which is located in the element accommodating section  52  to be functionally associated with the lower surface and the outer leads  43  of the drive IC  42 , is brought into contact with the lower surface and the outer leads  43  of the drive IC  42 . Therefore, as the heat conduction member  55  receives heat from the lower surface and the outer leads  43  of the drive IC  42  and transmits the heat to the lower cabinet  51   b , the heat is dissipated to the outside through the lower cabinet  51   b.    
         [0044]    That is to say, heat generated in the drive IC  42  is transmitted through its entire outer surface and the outer leads  43  to the heat conduction member  55 . Accordingly, almost all of the heat generated in the drive IC  42  can be transmitted to the heat conduction member  55 .  
         [0045]    Experimental temperature data obtained by the heat dissipators according to the present invention and the conventional art, respectively, are presented below in TABLE 1.  
                                         TABLE 1                                   Conventional   Present           lower cabinet   lower cabinet                                    Optical pick-up   63° C.   62° C.       Spindle motor   69° C.   72° C.       Step motor   71° C.   74° C.       DSP IC   75° C.   76° C.       RF IC   83° C.   84° C.       Drive IC   102° C.    86° C.       Lower cabinet   60° C.   63° C.       Internal Space   47° C.   46° C.                  
 
         [0046]    As can be readily seen from TABLE 1, in the case that the lower cabinet structure according to the present invention is applied to the heat dissipator, the drive IC  42  which usually has a highest temperature in an optical writing and/or reproducing apparatus is significantly reduced in its temperature to 86° C. when compared to its temperature of 102° C. under the conventional art. Further, a temperature of the lower cabinet  51   b  is slightly increased from 60° C. to 63° C. As a result, a person skilled in the art will readily recognize that, in the present invention, heat generated in the drive IC  42  is properly transmitted to the lower cabinet  51   b  through the heat conduction member  55  and dissipated to the outside.  
         [0047]    Of course, it is to be noted that the heat dissipator according to the present invention can be employed not only in the drive IC but also other heat generating elements which are installed on the circuit board.  
         [0048]    Preferably, the heat dissipating member comprises a heat dissipating pad.  
         [0049]    More preferably, the heat dissipating pad is made of a suitable material such as silicon.  
         [0050]    In the preferred embodiment of the present invention, as a heat generating element, the drive IC which is formed at both side surfaces thereof with the plurality of leads, was described. However, the present invention is not limited to this configuration of the drive IC, and it is possible to use a drive IC which is formed, at its four side surfaces, with leads. In this case, it is to be understood that four protrusions must be formed on the lower cabinet  51   b.    
         [0051]    As described above, in the present invention, since heat of the lower and side surfaces and the outer leads  43  of the drive IC  42  serving as a heat generating element in the optical writing and/or reproducing apparatus is transmitted to the heat conduction member  55  and dissipated to the outside through the lower cabinet  51   b , proper heat dissipation is ensured.  
         [0052]    Thus, because performance degradation of the heat generating element and surrounding parts due to overheating is prevented, operational reliability of the optical writing and/or reproducing apparatus can be improved.  
         [0053]    Moreover, due to the fact that the element accommodating section  52  is formed to have the same height as the remaining portion of the lower cabinet  51   b , the entire height of the optical writing and/or reproducing apparatus can be decreased.  
         [0054]    In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.

Technology Category: g