Abstract:
A vibration damper device for a disk drive which is equipped in a desktop computer or image reproducing apparatus and which includes a pick-up unit having a pick-up. A pick-up supporting unit has an upper supporting member and a lower supporting member positioned above and below the pick-up unit. The vibration damper has the pick-up unit fixed on its outer circumferential surface and a plurality of contact protrusions are formed on at least one surface among the upper surface and the lower surface attached to the pick-up unit supporting unit. A hole is formed in the vibration damper, and contact ribs are formed inside the hole to attenuate vibration generated in the disk drive efficiently, thereby minimizing vibrations transmitted to the outside.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a disk drive which is intended for being equipped in a notebook computer, a desktop computer, CD-Player or DVD-Player and which reproduces CDs and DVDs, and particularly, to an antivibration device for such a disk drive which dampens vibration and noise among components of the disk drive. 
     2. Description of the Background Art 
     Recently, the speed of optical disk drives such as a CD-ROM DRIVE and DVD-ROM DRIVE is becoming much improved as 16×, 24× and further 48× speed, and due to this speed-up of the optical disk drive, there occurs a serious problem of vibration in case of driving a disk. 
     Particularly, in case of high-speed driving of a disk with an inclined center of gravity, the force of internal vibrations generated during a rotational cycle of a disk increases in proportion to the rotational speed of the disk, and in a disk drive mounted in a portable information processing apparatus and the like, this internal vibration is transmitted to a user&#39;s hands or the vibration generates noise thus causes user&#39;s displeasure or may decrease a reading capacity of information written on a disk. Also, in a DVD which is a high-density disk, the track pitch is half of that of a compact disk and accordingly, the reproducing capability of a disk is significantly decreased by such vibration. 
     To prevent vibration in such drives, a vibration damping member is installed between a base having a motor which generates such vibration and a main base for supporting the base. 
     FIG. 1A is a perspective view showing a vibration damper for a disk drive in accordance with the conventional art and FIG. 1B is a cross sectional view showing a main portion of a disk drive in which the vibration damper shown in FIG. 1A is used. 
     With reference to FIG. 1B, a tray unit  3  which moves for receiving a disk is installed in the disk drive, and a cover  1  is installed under the tray unit  3 . 
     On the tray unit  3 , a plurality of internally threaded bosses  3   a  are formed, and the cover  1  is fixed on the tray unit  3  by screws  5  which are threaded into the bosses  3   a.    
     Between the cover  1  and the tray unit  3 , a pick-up unit (not shown) is positioned for recording a signal on a recording surface or reproducing the recorded signal. 
     Particularly, the pick-up base  9  for supporting the pick-up unit (not shown) is supported between the cover  1  and the tray unit  3  by vibration dampers  7  (only one of which is shown) so as to attenuate vibration and impact transmitted from external portions of the drive. A spindle motor (not shown) for rotating a disk is installed in the pick-up base  9 . 
     With reference to FIGS. 1A and 1B, each of the vibration dampers  7  is formed in a cylindrical form of rubber material, with a hole  7   a  therethrough inserted onto the bosses  3   a  of the tray unit  3 . 
     Also, an insertion groove  7   d  is formed in the circumferential surface of the vibration damper  7  so that the pick-up base  9  can be inserted thereinto. 
     In the vibration dampers  7 , the whole inner surface of the hole  7   a  is contacted with the outer surface of the bosses  3   a  and the upper and lower surfaces  7   b  and  7   c  respectively are contacted with the cover  1  and the tray unit  3 . 
     Therefore, the vibration damper  7  decreases vibration and impact transmitted between the pick-up base  9  and the cover  1  and the tray unit  3  in case of operating the drive. 
     However, the conventional vibration damper  7  for a disk drive has a disadvantage in that vibration damping characteristic thereof is reduced due to heat generated in a portable information processing apparatus and transmitted to the disk drive, since the upper and lower surfaces  7   b  and  7   c  support the pick-up base  9  in the condition that the surfaces are respectively adhered to the cover  1  and the tray unit  3  and accordingly the vibration damping characteristic is weakened since the vibration damper  7  can become softened and become stuck to the surfaces  7   b  and  7   c  when the interior environment of the disk drive is under a high temperature due to generation of heat in the electronic circuit elements installed in the disk drive. 
     Namely, since the vibration dampers  7  are made of a rubber material and is repeately subjected to cycles of high-temperature and low-temperature, their vibration damping capacity is declines. Particularly, because the upper and lower surfaces  7   b  and  7   c  are respectively contacted with the cover  1  and the tray unit  3 , accordingly, the amount of vibration amount transmitted to the cover  1  and the tray unit  3  through the vibration damper  7  relatively increases. 
     The vibration damping characteristics of the vibration damper  7  can be described with reference to FIG. 2 wherein the condition where vibrations generated when the disk drive is operating are transmitted to the outside is deemed as transmission rate 1 in a transmission curve. If the transmission rate is greater than 1, vibrations are amplified and transmitted to the outside and if the transmission rate is less than 1, vibrations are attenuated and transmitted to the outside. 
     The resonant frequency of the vibrations generated in the disk drive is 150 Hz and occurs at point B of the transmission curve in FIG. 2 exhibiting a maximum vibration transmission rate. 
     In case the disk drive is operated at 24× speed (24× the nominal “single” speed), the disk mounted in the drive rotates at 4,800˜5,000 rpm and the frequency of vibration is 85˜90 Hz. Point A in FIG. 2 represents the transmission rate in the case where the disk drive operates at 24× speed. The transmission rate according to the transmission curve is more than 1 and the vibration of the pick-up base  9  is amplified and transmitted to the outside due to a decrease in the vibration damping effect of the vibration damper  7 . 
     To solve the problem, a washer or powder is used between the vibration damper  7 , cover land the tray unit  3  to prevent the vibration damper from becoming softened and stuck under the conditions of high temperature and humidity. However, they increase the number of the components and complexity of the drive. 
     Particularly, since the conventional vibration damper  7  is installed in the condition that the upper and lower surfaces  7   b  and  7   c  are contacted with the cover  1  and tray unit  3  and the hole  7   a  is completely contacted with the bosses  3   a  to afford the vibration damping function, the resonant frequency is increased and accordingly, the damper can not attenuate vibrations sufficiently and thus transmits vibrations directly. Therefore, a user receives the vibration generated when operating the disk drive as it is. 
     A ball balance mechanism has conventionally also been applied to a turntable and the like in an attempt to solve the vibration problem. However, if a ball balance mechanism is used, the number of components increases thus increasing the cost. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide an antivibration device for disk drive which can minimize vibration transmitted to the outside by attenuating vibration generated in the disk drive efficiently, to solve the above problem. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an antivibration device for a disk drive which has a pick-up unit in which a pick-up is mounted to reproduce information recorded in a disk or record information in the disk with a pick-up unit supporting unit wherein an upper supporting member and a lower supporting member are positioned above and below the pick-up unit and the upper supporting member and lower supporting member are fixed mutually in a separated position having a certain space therebetween by a fixing member, the antivibratiion device comprising a vibration damper for supporting the pick-up unit between the upper supporting member and the lower supporting member of the pick-up unit supporting means, where the vibration damping means has the pick-up unit fixed on an outer circumferential surface thereof and a plurality of contact protrusions are formed on at least one surface among the upper surface and the lower surface thereof contacted with the pick-up unit supporting means. 
     A hole is formed penetrating the upper and lower surface of the vibration damping means so that the vibration damping means may be inserted over the outer end of the fixing member, and inside the hole, a plurality of contact ribs are formed to be contacted with the fixing member. 
     In accordance with the invention there is provided an antivibration device for a disk drive which includes a pick-up unit in which a pick-up is mounted to reproduce information recorded in a disk or record information in the disk, and a pick-up unit supporting means wherein an upper supporting member and a lower supporting member are positioned above and below of the pick-up unit and the upper supporting member and lower supporting member are fixed mutually in a separated position with a certain space therebetween by a fixing member, the antivibration damping means comprising a vibration damping means for supporting the pick-up unit between the upper supporting member and the lower supporting member of the pick-up unit supporting means, wherein the vibration damping means has means for fixing the pick-up unit fixed on an outer circumferential surface thereof, a hole is formed penetrating upper and lower portions of the vibration damping means so that the vibration damping means can be inserted onto an outer end of the fixing member, and a plurality of contact ribs are formed inside the hole to be contacted with the fixing member. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     In the drawings: 
     FIG. 1A is a perspective view showing a vibration damper for a disk drive in accordance with the conventional art; 
     FIG. 1B is a cross-sectional view showing a main portion of the disk drive in which the vibration damper shown in FIG. 1A is used; 
     FIG. 2 is a graph showing a transmission characteristic of the vibration damper in accordance with the conventional art; 
     FIG. 3 is a perspective view of a disk drive in which the vibration damper in accordance with the present invention is applied; 
     FIG. 4 is a rear elevation of a pick-up unit shown in FIG. 3; 
     FIG. 5 is a partially cutaway perspective view showing the vibration damper in accordance with the present invention; 
     FIG. 6 is a plan view of the vibration damper shown in FIG. 5; 
     FIG. 7 is a cross-sectional view taken along section line A—A of FIG. 3 showing the state that the vibration damper in accordance with the present invention is installed in the disk drive in FIG. 3; 
     FIG. 8 is a graph illustrating a transmission characteristic of the vibration damper in accordance with the present invention; 
     FIG. 9 is a plan view of a disk drive adopting the inventive vibration damper applied to a desktop computer or an image or an audio reproducer; and 
     FIG. 10 is a cross-sectional view taken along section line B—B of FIG. 9 showing the state that the vibration damper in accordance with the present invention is installed in the disk drive in FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     A plurality of embodiments of the antivibration device for a disk drive can be envisioned and hereinafter, more preferred embodiments will be described. 
     FIG. 3 is a perspective view of a disk drive in which the vibration damper in accordance with the present invention is applied. 
     With reference to FIG. 3, the disk drive includes a housing  11  in a front surface of which a tray insertion opening  12  is formed and a connector (not shown) is provided enabling the drive to be connected to a printed circuit board inside of a notebook computer to send and receive signals with the notebook computer. 
     A tray unit  13  is installed to be movable between a position in which it is completely inserted inside of the housing  11  and a removal position as shown, in which it extends out of the housing  11  for enabling the mounting or removing of a disk. 
     At the front end of the tray unit  13  a panel  15  is installed, to close the tray insertion opening  12  so that the tray insertion opening  12  is not visible from the outside when the tray unit  13  moves to the position in which it is completely inserted inside of the housing  11 . 
     In the tray unit  13 , a disk receiving portion  14  is formed and at one end, a pick-up opening  16  is formed at which is installed a pick-up unit  17 . 
     In the pick up unit  17 , a disk receiving portion  18  which corresponds to the disk receiving portion  14  of the tray unit  13  is formed at the position where the pick-up opening  16  is formed in the tray unit  13  and a pick-up moving opening  19  too is formed in a radial direction of the disk so that a pick-up  21  can move therein relative to the disk. 
     Also, a spindle motor  20  is installed at a central portion of the disk receiving portions  14  and  18  in the pick-up unit  17 . On the lower surface of the tray unit  13 , a plurality of bosses  40 , onto each of which a vibration absorbing member  32  is inserted, are protrudingly formed on the opposite surface from the disk receiving portion  14  near the pick-up opening  16 . 
     At three positions around the edges of the pick-up unit  17 , a corresponding number of vibration damper mounting portions  22  for each installing onto a respective vibration damper  32  is formed extending outwardly beneath the disk receiving portion  14 . 
     FIG. 4 shows the underside of the disk receiving portion of the pick-up unit  17 . 
     With reference to FIG. 4, at the right, left and upper edges of the pick-up unit  17 , the vibration damper mounting portions  22  are formed extending outwardly from the pick-up unit  17  respectively and at each vibration damper mounting portion  22 , a vibration damping member mounting opening  23  is formed. 
     Also, to move the pick-up  21  during the operation of the drive, a feeding motor  24  and a power transmission apparatus  25  are installed at one side for transmitting driving force of the feeding motor  24  to the pick-up  21 . 
     The power transmission apparatus  25  comprises a plurality of gears  26 ,  27  and  28  and a lead screw  29  connected to the gears  26 ,  27  and  28 . One end of the pick-up  21  is connected to the lead screw  29 . 
     Guide shafts  30 ,  31  are installed at the right and left sides of the pick up moving opening  19  in the pick-up unit  17  and the left and right side portions of the pick-up  21  are connected to the guide shafts  30  and  31  respectively. 
     Therefore, when the feeding motor  24  rotates, the driving force of the feeding motor  24  is transmitted to the gears  26 ,  27  and  28  and the lead screw  29  rotates. At this time, the pick-up  21  is guided along the guide shafts  30  and  31  and moves horizontally in the pick-up moving opening  19 . 
     FIG. 5 is a partially cutaway perspective view showing the vibration damper in accordance with the present invention. 
     The vibration damper  32  in accordance with the present invention has a generally cylindrical body  33 . In a central portion of the body  33 , an axially extending boss hole  34  is formed. On the upper and lower surfaces of the body  33 , a number of contact protrusions  35  and  36  are formed. 
     FIG. 6 is a plan view of the vibration damper. In the embodiment of the present invention, the contact protrusions  35  and  36  are respectively formed on the upper and lower surfaces of the body  33  at uniform intervals (six being shown by way of example). 
     The number of the contact protrusions  35  and  36  is determined in order to support the components which are contacted with the vibration damper  32  with a great balance. The number can be determined as more than 6, but since if there are too many contact protrusions, too much heat transmission from the components may result, it is desirable that a proper number of contact protrusions are formed in order to provide adequate contact while limiting heat transfer. 
     Also, the vibration damper  32  has a number of contact ribs  37  formed on the inner surface of the boss hole  34 . The contact ribs  37  are formed axially extending from the upper end to the lower end of the boss hole  34  at uniform intervals and the length of the contact ribs is formed shorter than the length of the boss hole  34 . 
     Therefore, the contact ribs  37  are spaced from the upper and lower ends of the boss hole  34 . 
     The contact ribs  37  make pre-contact with the element which is inserted into the boss hole  34 . In the illustrated embodiment of the present invention, the number of contact ribs  37  is 6 as shown in FIG.  6 . It is desirable that the number of contact ribs is set with a proper number as that of contact protrusions. 
     An insertion groove  38  is formed in the circumference of the body  33  of the vibration damper  32 . At the insertion groove  38 , the vibration damper mounting portion  22  of the pick-up unit  17  is inserted and supported. 
     FIG. 7 is a cross-sectional view taken along section line A—A of FIG. 3 showing the state that the vibration damper in accordance with the present invention shown in FIGS. 5 and 6 is installed in the disk drive in FIG.  3 . 
     With reference to FIG. 7, the boss hole  34  in the vibration damper  32  is inserted onto the boss  40  formed at the tray unit  13 . 
     In addition, a screw  44  which penetrates the cover  41  is threaded into the boss  40 . 
     Therefore, the vibration damper  32  is positioned between the cover  41  and the tray unit  13 . At this time, the surface  42  of the cover  41  contacts with the contact protrusions  35  of the vibration damper  32  and the surface  43  of and the tray unit  13  is also contacted by the contact protrusions  36  of the vibration damper  32 . 
     Also, the boss  40  inserted into the boss hole  34  contacts only with the contact ribs  37  inside the boss hole  34 . 
     The insertion groove  38  formed in the circumference of the vibration damper  32  has inserted thereonto the vibration damper mounting opening  23  which is formed at the vibration damper mounting portion  22  of the pick-up unit, thus to support the pick-up unit  17 . 
     The operation in case of the vibration damper being installed in the disk drive will be described next. 
     The vibration damper in accordance with the present invention is installed between the cover  41  and the tray unit  13  and supports the pick-up unit  17 . 
     Such vibration damper can block transmission of vibration between the cover  41 , tray unit  13  and pick-up unit  17 . 
     Namely, since the vibration damper  32  is made of rubber material and has a certain elasticity, vibrations generated from the pick-up unit  17  are absorbed thereby and is blocked so as not to be transmitted to the cover  41  or tray unit  13 . 
     At this time, contact between the vibration damper  32  and the cover  41  and between the vibration damper  32  and the tray unit  13  is by way of the contact protrusions  35  and  36  and thus the contact area is minimized. Therefore, heat generated during the operation of the disk drive is not well transmitted to the vibration damper  32 . However, vibration can be attenuated sufficiently. 
     Also, the contact ribs are formed axially at uniform intervals inside the boss hole  34  provide supporting contact between the boss hole  34  and the boss  40 . 
     On the other hand, the manner in which the contact ribs  37  are formed at the boss hole  34  enable to decrease the resonant frequency and minimize the contact area between the boss hole  34  and the boss  40  and the amount of material forming the vibration damper  32 . Therefore, the resonant frequency can be lowered without decreasing the hardness of the vibration damper. 
     In addition, due to the shape of the central portion of the vibration damper  32  and the contact protrusions  35  and  36 , transmission of vibrations to the outer portion can be minimized since the resonant frequency can be lowered while having same hardness as that of the conventional vibration damper. 
     FIG. 8 shows a vibration transmission characteristic curve  45  according to the change in frequency. 
     If the vibration damper  32  in accordance with the present invention is applied, the resonant frequency of the disk drive is remarkably lowered to the point B where the frequency is 65 Hz. 
     The transmission curve  45  is maximized at the resonant frequency, point B, and as the frequency increases, the transmission rate decrease remarkably. 
     The rotating frequency at 24× speed is 85˜90 Hz. At point A, the vibration transmission rate becomes about 0.4 and accordingly, vibration of the drive is attenuated by more than half. 
     FIG. 9 is a plan view of a drive incorporating the inventive vibration damper applied to a desktop computer or an image or an audio and/or video reproduction device. 
     As shown in FIG. 9, the drive  46  includes a main base  47  having a mounting surface  48  in the right side portion of the a main base  47  and a pick-up opening  49  is formed at the central portion of the a main base  47 . 
     An up-down movable base  50  is installed in the pick-up opening  49  and hinge portions  51  of the up-down movable base  50  are movably connected to the main base  47 . 
     A pick-up unit mounting surface  52  is formed at a front end of the up-down base  50  and a left side portion of a pick-up unit  53  is mounted on the pick-up unit mounting surface  52 . Also, a right side portion of the pick-up unit  53  are mounted on the mounting surface  48  of the main base  47 . 
     Pairs of bosses  60  and  61  are protrudingly formed on the mounting surface  48  of the main base  47  and a vibration damper  32  is installed on each of the bosses  60  and  61   
     In a central portion of the pick-up unit  53 , a pick-up moving opening  54  is formed and a pick-up  56  is guided on guide shafts  57  which are installed on the lower surface of the pick-up unit  53 . A spindle motor  55  for rotating a disk received theron is installed at a front end of the pickup unit  53 . 
     The vibration damper  32  according to the present invention is installed at the edge portion of the pick-up unit  53 . 
     FIG. 10 is a cross-sectional view taken along the section line B—B in FIG.  9 . In FIG. 10, the vibration damper according to the present invention is combined with the pick-up unit  53  and is supported between the supporting skirt portion  59  which is formed at the head portion of a screw  58  and the mounting surface  48  of the main base  47 . 
     Namely, after the vibration damper  32  is inserted over the outer end of the boss  60  which is formed on the mounting surface  48  of the main base  47 , the vibration damper  32  is supported so as not to be separated from the main base  47  by the supporting skirt portion  59  of the screw  58  which is threaded into the boss  60 . 
     Therefore, the upper surface of the vibration damper  32  is contacted with the supporting skirt portion  59  of the screw  58  by the contact protrusions  35  and the lower surface of the vibration damper  32  is also contacted with the mounting surface  48  of the main base  47  by the contact protrusions  36 . 
     Also, the contact ribs  37  which are formed around the boss hole in the vibration damper  32  are contacted with the boss  60 . 
     The pick-up unit is inserted and supported in the insertion groove  38  of the vibration damper  32 . 
     As shown in FIGS. 9 and 10, in the case that the vibration damper  32  in accordance with the present invention is applied to a desktop computer or an image or an audio reproducer, by virtue of the contact protrusions  35  and  36  and the contact ribs  37  which are formed in the vibration damper  32 , the vibration damper in accordance with the present invention can attenuate vibrations and impacts generated from the pick-up unit  53  easily and maintain the attenuating characteristic. 
     As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.