Abstract:
An optical disc drive having a retractable and ejectable disc carrying tray. A compound pivot mechanism engages a turntable with a disc carried on the tray. The turntable is supported by a base chassis which pivots with respect to a main frame. A sub-chassis is pivotably connected with the mainframe and elastically coupled with the base chassis. A cam member on the main frame engages the sub-chassis to pivot the sub-chassis coincident with the tray being retracted into the main frame or ejected from the main frame. The sub-chassis in turn pivots the base chassis to engage or disengage the disc with the turntable. The tray accommodates discs having different diameters and comprises mechanisms for securing the disc while the disc is retracted into and ejected from the main frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Application No. 2001-3415 filed Jan. 20, 2001, in the Korean Patent Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an optical disc drive, and more particularly, to an optical disc drive having an improved structure so that a slim optical disc drive is possible. 
     2. Description of the Related Art 
     In general, an optical disc drive such as a CD player or DVD player records information by emitting light onto a disc which is a recording medium or reproduces information by reading information from the disc. In a conventional optical disc drive as shown in FIG. 1, a tray  40  has a first receiving surface  41  for accommodating a disc  1  having a 120 mm diameter and a second receiving surface  42  for accommodating a disc (not shown) having a 80 mm diameter. The tray  40  moves into and out of a main frame  10  while carrying the disc. A pivoting sub-frame  20  is installed at the main frame  10 . A base chassis  30  is supported on the sub-frame  20 . 
     A turntable  32 , on which the disc  1  carried by the tray  40  is placed, and an optical pickup  31  for recording information on the disc  1  or reproducing information therefrom while moving across the disc  1  are installed on the base chassis  30 . A loading motor  11  drives the tray  40  to retract into and eject from the main frame  10  through a predetermined loading unit. Reference numeral  12  indicates a cam member having a cam groove (not shown) into which a cam protrusion  21  of the sub-frame  20  is inserted, for moving up and down the cam protrusion  21  according to the rotation of the loading motor  11 . Thus, as the cam member  12  rotates, the cam protrusion  21  ascends and descends while moving along the trace of the cam groove. Accordingly, the sub-frame  20  pivots around a pivot axis passing through pins  22  supported by the main frame  10 . 
     In the disc drive as shown in FIG. 1, where a disc  1  is placed on the tray  40  and the tray  40  enters the main frame  10 , the cam member  12  is rotated and the sub-frame  20  pivots so that the disc  1  is placed on the turntable  32 . Then, the turntable  32  rotates and the optical pickup  31  reproduces information recorded on the disc  1  or records new information thereon. 
     However, in the above conventional optical disc drive, since the cam protrusion  21  provided at the sub-frame  20  is directly inserted in the cam member  12  and thus the sub-frame  20  is moved up and down by the cam motion between the cam protrusion  21  and the cam member  12 , the cam member  12  is required to be located at a position lower than the lowest position in which the cam protrusion  21  is located in a range that the sub-frame  20  pivots. That is, as shown in FIG. 2, to secure the elevation height of the turntable  32  according to pivot of the sub-frame  20 , the cam member  12  inevitably occupies a space down at a lower position (h+h1) out of a pivot range (h) of the sub-frame  20 . Thus, this pivot structure occupying a large space of the optical disc drive in height is considered to be an inappropriate structure considering a current trend in which products are made light and thin. 
     Another problem in making an optical disc drive slim is that, where an 80 mm disc is carried by being placed on the second receiving surface  42  of the tray  40 , the disc is caught by a boss  32   a  of the turntable  32  so that the tray  40  may not be moved. For example, when the 80 mm disc placed on the turntable  32  is taken out, the sub-frame  20  is lowered and pivots to place the disc on the second receiving surface  42  of the tray  40  so that the tray  40  is taken out of the main frame  10 . When the lowering height of the turntable  32  is too small in order to making an optical disc drive slim, the disc is caught by the boss  32   a  (FIG. 1) of the turntable  32  so that the tray  40  is not easily ejected from the main frame  10 . Where the lowering height of the turntable  32  is too large, it is difficult to make an optical disc drive slim. Thus, there is a need to prevent the disc from being caught by the boss  32   a  while making the lowering height small. 
     In another conventional optical disc drive, a turntable or optical pickup is directly installed on the tray to realize a slim optical disc drive for notebook computers. However, in most cases, tray motions such as entering in or ejecting from the main frame are manually performed which inconveniences a user. Thus, an optical disc drive having a structure to solve the above problems is needed. 
     SUMMARY OF THE INVENTION 
     To solve the above problems, it is an object of the present invention to provide an optical disc drive having an improved structure which enables automatic tray loading and a slim optical disc drive. 
     Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     According to the present invention, a disc carrying tray is supported by a main frame. A base chassis is pivotable with respect to the main frame and supports a turntable which rotates a disc. The turntable is common with a rotor of a spindle motor which drives the turntable. 
     The base chassis has a free end which is elastically coupled with a free end of a sub-chassis which also pivots with respect to the main frame. An optical pickup, which records information on and reproduces information from the disc, is mounted on the base chassis. A feeding unit moves the optical pickup in a radial direction of the disc to record information on and/or reproduce information from the disc. A tray loading unit retracts the tray into and ejects the tray from the main frame. 
     A cam member has a cam groove which is slidingly engaged with a cam protrusion on the sub-chassis. The cam member is operationally engaged with the tray loading unit to pivot the sub-chassis as the tray loading unit retracts the tray into or ejects the tray from the main frame. The sub-chassis pivots the base chassis to engage the turntable with the disc or to disengage the turntable from the disc. 
     A loading motor drives a gear rail on the tray loading unit via a loading gear. A cam gear, selectively engaged with the cam member, transfers the driving force of the loading motor to the cam member. The disc drive comprises a latch which prevents escape of the tray where the tray is retracted into the main frame. The latch comprises a hooking piece formed on the tray which engages an interference piece provided on the cam gear to block a return path of the hooking piece where the tray is retracted. 
     The feeding unit comprises a guide rail arranged at the base chassis along a radial direction of the disc and a lead screw installed parallel to the guide rail to be rotated and driven by a motor. A gear portion provided at one side of the optical pickup is coupled to the lead screw. 
     The tray comprises an outer surface and a first disc receiving surface. The first disc receiving surface is formed to be recessed from the outer surface and to accommodate a disc having a first diameter. A stepped portion connects the outer surface and the first disc receiving surface. 
     The tray further comprises an escape preventing unit which prevents the disc from escaping from the tray by pressing the disc placed on the first disc receiving surface against the stepped portion in a direction opposite the direction in which the tray retracts. A rotary lever is installed at the outer surface of the tray. An elastic member provides an elastic force to urge the rotary lever in a direction to push the disc against the stepped portion. A locking protrusion protrudes from the outer surface of the tray toward the rotary lever to prevent the disc from being pushed above the outer surface. 
     A second disc receiving surface is formed to be recessed from the first disc receiving surface for accommodating a disc having a smaller diameter than the disc which is accommodated by the first disc receiving surface. The second disc receiving surface is inclined such that a depth of the second disc receiving surface decreases in a direction in which the tray retracts into the main frame. 
     A plurality of receiving pads for supporting the bottom surface of a disc placed on the first disc receiving surface are installed at a boundary portion between the first and second disc receiving surfaces. The pads support the disc where the disc is placed on the first disc receiving surface and/or edge portions of the disc where the disc has the smaller diameter to prevent the disc having the smaller diameter from escaping from the second disc receiving surface. 
     First and second sensors which generate loading and unloading operation signals are mounted on the main frame. A knob on the tray operates the first sensor to start an ejection operation and a protrusion mounted on the mainframe operates the second sensor where the tray is completely ejected from the main frame. Where the tray is completely retracted into the main frame, the knob is pressed to generate a tray unloading operation signal. Where the tray is completely ejected from the main frame and the tray is pushed into the main frame, the switching protrusion operates the second sensor to generate a loading operation signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which: 
     FIG. 1 is a perspective view showing a conventional optical disc drive; 
     FIG. 2 is a view showing a pivot structure of a sub-frame in the optical disc drive of FIG. 1; 
     FIG. 3A is a perspective view showing an optical disc drive according to the present invention; 
     FIG. 3B is an enlarged cut away view of a portion  3 B of FIG. 3A; 
     FIG. 4 is a section view taken along line  4 — 4  of FIG. 3A; 
     FIG. 5 is a view showing a pivot structure of the base chassis in the optical disc drive shown in FIG. 3A; 
     FIG. 6 is a sectional view showing the turntable and spindle motor shown in FIG. 3A; 
     FIG. 7 is a sectional view showing the tray shown in FIG. 3A; 
     FIG. 8 is a perspective view showing the bottom surface of the tray shown in FIG. 3A; 
     FIG. 9 is a perspective view for explaining an inconvenience in loading a disc where the rotary lever is positioned differently from the position shown in FIG. 3A; 
     FIGS. 10A and 10B are views for explaining a problem of eccentricity of the disc generated where the rotary lever us positioned differently from the position shown in FIG. 3A; and 
     FIGS. 11 through 13 are sequential views showing a loading process. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     Referring to FIGS. 3A and 3B, in an optical disc drive according to the present invention, a tray  300  for carrying a disc  1  is adapted to retract into and eject out of a main frame  100  and a base chassis  200  is adapted to pivot with respect to the main frame  100 . A turntable  231  on which the disc  1  is placed and an optical pickup  220  for recording information on or reproducing information from the disc  1  while the optical pickup  220  is moving across the disc  1  are installed at the base chassis  200 . A damper  201  connects the main frame  100  and the base chassis  200  and simultaneously functions as a pivot axis of the base chassis  200 . 
     A tray loading unit enables the tray  300  to retract into the main frame  100  and a base chassis loading unit enables the base chassis  200  to pivot so that the disc  1  placed on the tray  300  is accommodated on the turntable  231 . The tray loading unit and the basis chassis loading unit are structured to make a slim disc drive. Referring to FIG. 3A, the tray loading unit comprises a loading motor  110 , and a loading gear  120  for retracting the tray  300  into and ejecting the tray  300  from the main frame  100 . The loading motor  110  rotates the loading gear  120  which is engaged with a gear rail  301  provided at an inner side wall of a lower surface of the tray  300 . The loading gear  120  and the gear rail  301  are engaged laterally, using an otherwise empty space under the tray  300 , thus the loading gear  120  and the gear rail  301  are arranged in a relatively low profile. A cam gear  130  rotates by being pushed by an engagement protrusion  302  provided at the tray  300  and engaged with the loading gear  120  as the tray  300  retracts into the main frame  100 . The cam gear  130  selectively transfers power of the loading motor  110  to the base chassis loading unit. 
     The base chassis loading unit pivots the base chassis  200  and comprises a cam member  140  and a sub-chassis  210 . The cam member  140  slides over the main frame  100  according to the rotation of the cam gear  130  by being engaged with the cam gear  130 . The cam member  140  has a cam groove  141   a  (FIG. 11) installed at one side for elevating the base chassis  200 . The sub-chassis  210  is installed at the main frame  100  to pivot and has a free end portion  210   a  which is elastically coupled to a free end portion  200   a  of the base chassis  200  via dampers  202  (see FIG. 4) interposed between the two free end portions  200   a  and  210   a  and a cam protrusion  211  inserted in the cam groove  141   a . Thus, where the cam member  140  is moved by the rotation of the cam gear  130 , the cam protrusion  211  slides along the cam groove  141   a  so that the sub-chassis  210  pivots. Accordingly, the free end portion  200   a  of the base chassis  200  ascends so that where the disc  1  is placed on the tray  300 , the disc  1  is supported on the turntable  231 . The above operation will be described in greater detail below. 
     The base chassis  200  is not directly connected to the cam member  140 , but is connected via the sub-chassis  210  to obtain a slim optical disc drive. If a cam protrusion were to protrude from the free end portion  200   a  of the base chassis  200  and connect directly to the cam groove  141   a  of the cam member  140 , the cam member  140  would need to be located at a position lower than the lowest position of the free end portion  200   a  of the base chassis  200 . However, according to the present invention, the free end portion  200   a  of the base chassis  200  is coupled to the free end portion of the sub-chassis  210  and the cam protrusion  211  is formed on the sub-chassis  210 , as shown in FIG.  5 . Thus, the cam member  140  is located at a position higher than the lowest position of the free end portion  200   a  of the base chassis  200 . Further, since the cam member  140  is positioned within a pivot range of the base chassis  200 , no additional height is needed so that the arrangement shown in FIG. 5 is advantageous in making a slim optical disc drive. 
     Also, where the disc  1  is placed on the turntable  231 , the feeding unit moves the optical pickup  220  in a radial direction of the disc  1  so that the optical pickup  220  can record information on and reproduce information from the disc  1 . Referring now to FIGS.  11 , 12  and  13 , the feeding unit comprises a guide rail  240  for guiding the movement of the optical pickup  220 , a lead screw  250  arranged parallel to the guide rail  240 , a gear portion  221  provided at the optical pickup  220  and engaged with the lead screw  250 , and a motor  260  for driving the lead screw  250 . Thus, as the lead screw  250  is rotated by driving of the motor  260 , the optical pickup  220  coupled to the lead screw  250  via the gear portion  221  moves along the guide rail  240  and emits light onto the disc  1 . 
     Referring now to FIG. 6, the turntable  231  is formed integral with the rotor of a spindle motor  230  and rotates about spindle  233 . A boss  231   a  is formed on the turntable  231  to receive a center hole  1   a  of the disc  1 . The turntable  231  is rotated by the electrical interaction of the rotor portion of the turntable  231  with a stator  232 . This motor arrangement is also advantageous in reducing the thickness of the optical disc drive. 
     Referring now to FIGS. 7 and 8, the tray  300  comprises an outer surface  310  and a disc receiving surface  320 . The disc receiving surface  320  is recessed from an outer surface  310  so that the disc  1  may be placed thereon. The disc receiving surface  320  comprises a first disc receiving surface  321  for accommodating a disc having a diameter of 120 mm and a second disc receiving surface  322  for accommodating a disc having a diameter of 80 mm. The second disc receiving surface  322  is more recessed from the outer surface  310  than the first disc receiving surface  321 . The second disc receiving surface  322  is inclined so that an edge of the disc in a direction in which the tray  300  retracts is higher than an edge of the disc in a direction in which the tray  300  ejects, where the directions of retraction and ejection are indicated by the arrows A 1  and A 2 , respectively, in FIG. 7. A distance that the turntable  231  is lowered to allow the disc  1  to retract and to eject is reduced as the optical disc drive is made slim. Thus, where the tray  300  is ejected, the 80 mm disc may be caught by the boss  231   a  of the turntable  231  after the base chassis  200  is completely lowered. To prevent the above problem, as shown in FIG. 7, the second disc receiving surface  322  is formed to be inclined at a predetermined angle θ to gradually rise in the direction A 1  in which the tray  300  retracts. Accordingly, since the tray  300  is ejected in a direction indicated by arrow A 2  while a disc  1 — 1  is inclined, slight lowering of the turntable  231  can prevent the disc  1 — 1  from being caught by the boss  231   a.    
     A disc escape preventing apparatus is provided on the tray  300  so that where the disc drive is installed vertically and the disc  1  is placed on the first disc receiving surface  321 , the disc  1  is supported and escaping of the disc  1  is prevented. The disc escape preventing apparatus prevents escape of the disc  1  by pressing the edge portion of the disc  1  placed on the first disc receiving surface  321  in a radial direction toward a stepped portion  315  between the outer surface  310  and the first disc receiving surface  321 . As shown in FIGS. 3A and 8, the disc escape preventing apparatus includes a rotary lever  351  rotatably installed at the outer surface  310  and a torsion spring  352  for elastically biasing the rotary lever  351  in a direction in which a pressing groove  351  a presses the edge portion of the disc  1 . Thus, escape of the disc  1  placed on the first disc receiving surface  321  is prevented as the disc  1  closely contacts the step portion  315  at the opposite side. The rotary lever  351  is installed at the outer surface  310  of the tray  300  so that the rotary lever  351  is close to the main frame  100  where the tray  300  is in an ejected position. Thus, the disc  1  is pressed against the stepped portion  315  disposed far from the main frame  100 . 
     The direction in which the rotary lever  351  presses the disc  1  is convenient for loading the disc  1 . If the rotary lever  351  is installed at the outer surface  310  far from the main frame  100 , as shown in FIG. 9, the disc  1  must be loaded by pressing the rotary lever  351  in a direction indicated by arrow B. Here, where the disc  1  is loaded in the direction B, a hand of a user holding the disc  1  contacts a main body  400  of the optical disc drive, which which makes loading the disc  1  inconvenient. In contrast, where the rotary lever  351  is arranged as shown in FIGS. 3 and 8, that is, the disc  1  is loaded on the first disc receiving surface  321  in a direction toward the main frame  100 , the inconvenience described with reference to FIG. 9 does not occur. 
     Referring again to FIGS. 3 and 8, the direction in which the rotary lever  351  presses the disc  1  is advantageous in that the center of rotation of the turntable  231  matches the center of the disc  1  when the disc  1  is placed on the turntable  231 . If the disc  1  is loaded in the direction B as shown in FIG. 9, the disc  1  is placed on the first disc receiving surface  321  by being deviated toward the inside of the main frame  100  as indicated by an arrow C in which the tray  300  retracts, as shown in FIG.  10 A. However, since the turntable  231  lifts the disc  1  while pivoting as shown in FIG. 10A, where the disc  1  is deviated toward the main frame  100 , the turntable lifts the disc  1  at a point that is deviated from the center of the disc  1  in the direction far from the main frame  100 . Thus, eccentricity as much as a distance d is generated. However, in the present invention, as shown in FIG. 10B, the rotary lever  351  urges the disc  1  to be deviated in a direction indicated by an arrow D, opposite the direction of the arrow C of FIG.  10 A. Where the turntable  231  pivots to lift the disc  1 , the centers of the turntable  231  and the disc  1  are well matched and disc loading becomes convenient and the eccentricity of the disc is reduced. 
     A thickness of the rotary lever  351  which is less than the height of the stepped portion  315  is advantageous in making a slim optical disc drive. Where the tray  300  is almost fully retracted into the main frame  100 , an end portion  351   b  (FIG. 3A) of the rotary lever  351  engages a stopper  101  provided at the main frame, rotating the rotary lever  351  so that the pressing toward the disc  1  is removed. Where the rotary lever  351  presses the disc  1  against the stepped portion  315 , a locking protrusion  330  prevents the disc  1  from being pushed over the outer surface  310 . 
     A plurality of receiving pads  340  are installed at a boundary portion between the first and second disc receiving surfaces  321  and  322 . Where a 120 mm disc is used, the receiving pads  340  support a bottom surface of the 120 mm disc. Where an 80 mm disc is used, the receiving pads  340  support a side edge portion of the 80 mm disc so that the 80 mm disc cannot escape from the second disc receiving surface  322 . Since the receiving pads  340  are installed inwardly with respect to an outer edge portion of the 120 mm disc, the outer edge portion of the disc  1  has a margin for slightly moving up and down. Where there is a margin for the edge portion of the disc  1  to move, it becomes easy to load the disc  1  while fitting the edge portion of the disc  1  to the pressing groove  351  a of the rotary lever  351 . 
     Referring now to FIGS. 3A and 3B, a curved hooking piece  303  extending from the engagement protrusion  302  is provided at the bottom surface of the tray  300 . The hooking piece  302 , together with an interference piece  131  provided at a horizontal surface of the cam gear  130 , functions as a locking means for preventing escape of the tray  300 . That is, as the tray  300  retracts into the main frame  100 , the cam gear  130  rotates and the interference piece  131  is moved to a position for blocking a return path of the hooking piece  303  so that the tray  300  cannot escape from the main frame  100 . 
     First and second switches S 1  and S 2  sense loading and unloading actions of the tray  300 , respectively. The first and second switches S 1  and S 2  are operated by a knob  300   a  and a switching protrusion  300   b  provided at the tray  300 . Where the tray  300  completely retracts into the main frame  100 , the first switch S 1  is disposed to contact the knob  300   a  (see FIG.  13 ). Thus, where the knob  300   a  is pressed in this state, the first switch S 1  is also pressed and operated to generate a signal for driving the loading motor  110  in the direction in which the tray  300  is ejected. Where the tray  300  is completely ejected from the main frame  100 , the switching protrusion  300   b  contacts the second switch S 2 . With the tray  300  ejected, where the tray  300  is slightly pushed into the main frame  100 , the switching protrusion  300   b  is separated from the second switch S 2  (refer to FIG.  11 ), to generate a signal for driving the loading motor  1100  to retract the tray  300  into the main frame  100 . Thus, the tray  300  is unloaded by pressing the knob  300   a  and the tray  300  is loaded by slightly pushing the tray  300 . 
     The disc loading operation of the optical disc drive according to the present invention is performed as follows. Assuming that a disc having a 120 mm diameter is used, the disc  1  to be used is placed on the first disc receiving surface  321  of the tray  300  and the edge of the disc  1  is placed to fit in the pressing groove  351   a  of the rotary lever  351 . Thus, the disc  1  is firmly supported on the first disc receiving surface  321  by a pressing force of the rotary lever  351  by the torsion spring  352 . 
     With the disc loaded on the tray  300 , the tray  300  is slightly pushed into the main frame  100 , separating the switching protrusion  300   b  from the second switch S 2 , so that the loading motor  110  is driven. As shown in FIG. 11, the loading gear  120  engaged with the gear rail  301  is rotated, and the tray  300  retracts into the main frame  100 . 
     Where the tray  300  is almost fully retracted into the main frame  100 , as shown in FIG. 12, the engagement protrusion  302  at the bottom surface of the tray  300  pushes a protruding portion  132  of the cam gear  130  so that the tray  300  is slightly pushed upward. Accordingly, the cam gear  130  is engaged with the loading gear  120  and as the loading gear  120  rotates the cam gear  130  is rotated so that the cam member  140  slides. Here, as one end portion  351   b  of the rotary lever  351  is engaged by the stopper  101  and the tray  300  retracts, the rotary lever  351  is rotated. Thus, the pressing force to the disc  1  is removed. 
     As the cam member  140  is moved, the sub-chassis  210  pivots by a cam motion of the cam groove  141   a  and the cam protrusion  211 . Simultaneously, the base chassis  200  having the free end portion  200   a  connected to the free end portion  210   a  of the sub-chassis  210  pivots. As a result, as shown in FIG. 13, as the base chassis  200  ascends, the disc  1  is received on the turntable  231 . 
     Here, the interference piece  131  of the cam gear  130  returns to the position in which a returning path of the hooking piece  303  of the tray  300  is blocked. Thereafter, the feeding unit moves the optical pickup  220 , to perform recording or reproducing information on or from the disc  1 . When the first switch S 1  is operated by pressing the knob  300   a , the unloading action is performed in the reverse order. Thus, loading and unloading actions can be automatically performed in the slim optical disc drive of the present invention. 
     As described above, in the optical disc drive according to the present invention, automatic loading and unloading of the tray is realized and a space for a pivot is reduced, so that an entire thickness of the optical disc drive is reduced. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.