Disc drive

Abstract: A disc drive includes a drive mechanism 60 having an operative gear 65 rotated by a motor. The operative gear 65 carries out a first operation which moves a disc tray between a disc loading position and a disc eject position with a cam mechanism being held at the first position, when the operative gear is engaged with a first rack of the disc tray, and the operative gear carries out a second operation which displaces the cam mechanism between the first position and the second position when the operative gear is engaged with the second rack, thereby displacing a mechanism unit 42 provided with a turntable between a raised position and a lowered position. By constructing in this way, it is possible to provide a disc drive which has a simple structure formed form a small number of parts and which can be assembled with fewer steps. The mechanism unit is formed from a base frame 43 and a support member 44 which is supported on the base frame through three elastic members arranged at predetermined positions, thereby enabling to prevent vibrations generated by the rotation of the disc from being transmitted to the base frame, the chassis and the casing.

Description: The present invention relates to a disc drive according to the preamble of claim 1 and provided for playing back or recording and playing back a disc such as an optical disc or the like. Such a disc drive is known from EP 0 416 797 A2. A disc drive unit is mounted on a supporting plate in a floating state by means of four compression coil springs. Four supporting pins provided on the upper surface of the supporting plate are introduced into supporting holes at the four corners of a unitary base member. Retention members are provided at the forward sides of the four supporting pins for inhibiting accidental extrication of the supporting pins, and the compression coil springs are wrapped about the supporting pins and interposed in this state between the base member and the disc drive unit supporting plate. EP 0 539 199 A2 describes a loading apparatus for disc cartridges. A supporting base plate of a disc driving unit is supported for displacement on a stationary substrate by means of three elastic supporting members which are formed of an elastic material such as rubber and exhibit a vibration-absorbing function. The elastic supporting members are arranged to roughly form an isosceles triangle, whereby the disc rotating and driving unit is mounted at a mid part of the supporting base plate, so that a spindle shaft driving a disc table by a spindle motor is arranged at a mid part between the elastic supporting members. In view of the problems described above, it is the object of the present invention to provide a disc drive having a simple construction which makes it possible to prevent the transmission of vibrations generated due to high speed rotation of a disc. The present invention is directed to a disc drive according to the features of claim 1. Special embodiments are defined in the subclaims. According to the invention, the mechanism unit is constructed from the base frame and the support member on which the turntable or the like are provided, and the support member is supported on the base frame by means of three elastic members which are arranged at the left and right sides of the turntable and the back side of the turntable. By such an arrangement of the elastic members, it is possible to effectively absorb vibrations generated by eccentric rotation of the optical disc, thereby enabling to prevent such vibrations from being transmitted to the base frame or the chassis. In particular, since the drive mechanism (loading mechanism) is accomodated in a limited space of the chassis in front of the mechanism unit, it is possible for the mechanism unit to have a sufficient width. As a result, it is possible to arrange the elastic members at the corner positions of the base frame so as to have a sufficient distance therebetween at the right and the left sides of the front of the turntable, and such an arrangement of the elastic members are particularly effective for absorbing the vibrations. In this disc drive, it is preferred that the base frame is formed into a substantially rectangular shape and has rotation axles at the opposite sides of the rear portion thereof, respectively, and the support member is formed into a substantially rectangular shape so as to be accomodated within the base frame, and the support member is supported on the base frame through the elastic members at the three-postions including right and left corners of the front portion of the support member and a substantially middle point of the rear portion thereof. Other objects, structures and advantages of the present invention will be apparent when the following description of the preferred embodiment is considered taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 2 is a perspective view of a disc drive of an embodiment according to the present invention; Fig. 3 is a planar view of a main body of the same embodiment, in which a mechanism unit is shown in a lowered position; Fig. 4 is another planar view of the main body of the same embodiment, in which the mechanism unit is shown in a raised position; Fig. 5 is a bottom view of the construction of the underside of a disc tray of the disc drive shown in Fig. 2; Fig. 6 is a perspective view showing the structure of elastic members used in the disc drive shown in Fig. 2; Fig. 7 is a perspective view showing the structure of a cam member used in the disc drive shown in Fig. 2, in which the cam member is shown in a first position; Fig. 8 is a perspective view showing the structure of the cam member used in the disc drive shown in Fig. 2, in which the cam member is shown in a second position; and Fig. 9 is a perspective view showing the structure of a disc clamp used in the disc drive shown in Fig. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed description of the preferred embodiments of a disc drive will now be given below with reference to the appended drawings. In this connection, it is to be noted that the same reference numbers will be used for the parts of components of the present invention that are similar to the parts or components of the prior art disc drive described above. Fig. 2 is a perspective view of an embodiment of a disc drive 1A. Fig. 3 is a planar view of a main body 2 of the same embodiment, which shows a state in which a mechanism unit 42 is shown in a lowered position (lower position), and Fig. 4 is another planar view of the main body 2 of the same embodiment, which shows a state in which the mechanism unit 42 is shown in a raised position (upper position). As shown in Fig. 2, the disc drive 1A is a device for playing back or recording and playing back an optical disc 3, such as a CD-ROM or audio CD, in the same manner as the prior art device shown in Fig. 9. The disc drive 1A is roughly constructed from a casing 10 which houses the main body (mechanism assembly), a disc tray 5 which moves in the forward and backward direction (horizontal direction) with respect to the casing 10 in order to transport the optical disc 3, and a circuit substrate assembly (not shown in the drawings) provided in a bottom portion of the main body. In the same manner as was described above for the prior art apparatus shown in Fig. 1, the casing 10 is constructed from a plurality of metal plates, with the front portion thereof being provided with a front panel having an aperture 13a. As shown in Figs. 2 and 3, the main body 2 which is housed inside the casing 10 is shaped roughly like a container and includes a chassis 40 which is preferably constructed from a hard resin. The chassis 40 is constructed from a roughly rectangular-shaped bottom portion and a U-shaped wall portion 40a which stands erect along the left, right and back edge portion of the bottom portion 40a. In this way, no wall portion is formed in the front of the chassis 40 in order to allow the front of the chassis to be open. Further, when the main body 2 is assembled into the casing 10, the open front portion of the chassis 40 is aligned with the aperture 13a of the front panel 13 provided on the casing 10. As shown in Fig. 2, the disc tray 5 is provided with a shallow concave disc supporting portion 5a into which the optical disc 3 is placed to enable the optical disc 3 to be transported to a prescribed disc loading position. As shown in Fig. 5, on the left and right portions of the bottom portion 40a of the chassis 40, there are provided with protruding guide members 40g (Figs. 2, 3) which engage with guide grooves 5L, 5R formed in left and right side portions of the underside surface of the disc tray 5. Further, the underside surface of the disc tray 5 is further provided with a rack gear 6 which includes a first rack 6a which extends in a straight line in the forward and backward direction along the guide groove L and a roughly 90 degree arc-shaped second rack 6b which is formed at the front end portion (the front side of the disc tray 5, as shown in the lower portion of Fig. 5) of the first rack 6a so as to be continuous therewith. Further, as shown in Fig. 5 a cam member movement restricting groove 7 is provided on the underside surface of the disc tray 5 along the guide groove 5R which is positioned at the opposite side of the first rack 6a. This cam member movement restricting groove 7 is constructed from a first movement restricting groove 7a which extends parallel to the first rack 6a, a second movement restricting groove 7b which slants at a roughly 45 degree angle with respect to the first movement restricting groove 7a, and a third movement restricting groove 7c which slants at a rougly 45 degree angle with respect to the second movement restricting groove 7b. Accordingly, the third movement restricting groove 7c is arranged at a roughly 90 degree angle with respect to the first movement restricting groove. Further, as shown in Figs. 3 and 4, the chassis 40 is provided with a mechanism unit 42 equipped with a turntable 46 for rotating an optical disc 3, and optical head (optical pick-up) 47 for playing back or recording and playing back the optical disc 3. The mechanism unit 42 is arranged inside a roughly rectangular-shaped opening 41 formed in the bottom portion 40a of the chassis 40, with the rear portion of the mechanism unit 42 being supported in a manner that makes it possible for such rear portion to pivot with respect to the chassis 40 in order to enable the front portion of the mechanism unit 42 to be displaced between a raised position (upper position; Fig. 4) in which the optical disc 3 is supported on the turntable 46 and a lowered position (lower position) which is lower than the raised position. In particular, as shown in Figs. 3 and 4, the mechanism unit 42 includes a base frame 43 constructed preferably from hard resin, and a support member (support plate) 44 which supports the base frame 43 via an elastic member (insulator) 441. The base frame 43 is formed so as to have a roughly rectangular shape which includes a front portion and a rear portion. Formed on the left and right side portions of the rear side of the base frame 43 (the back portion of the main body 2) are protruding axles 431, 432 which act as pivotal axles to enable the mechanism unit 42 to pivot with respect to the chassis 40. These axles 431, 432 are inserted into respective axle holes 433, 434 formed in the opposite inner sides of the chassis 40. By supporting the rear portion of the mechanism unit 42 with the axles 431, 432 in this way, the front portion of the mechanism unit 42 is able to pivot with respect to the chassis 40 between the lowered position shown in Fig. 3 and the raised position shown in Fig. 4. Further, a pair of protruding guide pins 43a, 43b are formed on the front of the base frame 43 (see Figs. 6 and 7). These guide pins 43a, 43b are engaged respectively with a pair of guide slots (not shown in the drawings) formed in the wall of the front portion of the chassis 30 which defines the opening 41 of the chassis 40, and this enables the front portion of the base frame 43 to be guided up or down. Taking the possibility of deformation (thermal deformation or the like) of the chassis 40 into account, a spacing 41G is provided between the base frame 43 and the chassis 40 which defines the opening 41. Specifically, this spacing 41G is provided around roughly the entire circumference of the base frame 43, and in this way the pivotal movement of the base frame 43 is not hindered even when the chassis 40 undergoes maximum distortion. The support member 44 is constructed from a roughly rectangular-shaped bottom portion 44a and a wall portion 44b formed around the circumference of the bottom portion 44a. The wall portion 44b is one size smaller than the base frame 43 such that the wall portion 44b is arranged inside the frame of the base frame 43 via a prescribed spacing 43G. According to the support member 44 is supported by the base frame 43 via the elastic members (insulators) 441 provided on tabs 43T formed at the left and right corner portions of the front side of the base frame 43 and at roughly the middle of the rear portion of the base frame 43. Namely, the support member 44 is supported by the base frame 43 via the elastic members 441 provide at three points which roughly form an isosceles triangle. As shown in Fig. 6, each elastic member 441, which is formed from an elastic material such as rubber or the like, has a roughly cylindrical shape and includes a center hole 441a and a groove 441b formed in the outer circumferential surface in a circumferential direction thereof. Further, when the elastic members 441 are arranged in place to support the support member 44 on the base frame 43, the center hole 441a of each elastic member 441 fits onto an axis provided on the respective tabs 43T of the base frame 43 and then the groove 441b fits over a respective notched portion formed at the corresponding position of the support member 44. Further, as shown in Figs. 3 and 4, the support member 44 is provided with a spindle motor (not shown in the drawings) for rotating an optical disc 3, a turntable 46 fixed to a rotation axis 45 of the spindle motor, and optical head (optical pick-up) 47 (which includes an actuator), and an optical head moving mechanism 48 for moving the optical head 47 in the radial direction of the optical disc 3. The spindle motor is capable of rotating the optical disc 3 at a high rotational speed, for example at a speed capable of rotating the optical disc 3 at 200 - 6400 rpm. The turntable 46 is a disc-shaped member which includes a protruding ring-shaped center hub 46a formed in the center portion of the turntable 46. This center hub 46a is adapted to fit into a center hole 3a of the optical disc 3. Further, the center hub 46a is formed so as to taper from the tip to the base in order to prevent the optical disc 3 from slipping off center when placed on the turntable 46. Further, a ring-shaped permanent magnet 46b for creating an attraction force on a disc clamp (described below) is provided in the center hub 46a in the circumferential direction of the rotation axis 45 of the spindle motor. Further, a ring-shaped pad 46c is bonded to the upper part of the turntable 46 (i.e., the side used to support the optical disc 3) around the circumference of the center hub 46a. The pad 46c is made from an elastic material, such as various rubbers, soft resins or porous materials (sponges), which is constructed so as to have a relatively high coefficient of friction in order to prevent the optical disc 3 from slipping. The optical head 47 is a flat type optical head (pick-up) constructed so as to deflect light reflected from the optical disc 3 by roughly 90 degrees using a mirror (or prism) or the like to guide such light toward a light gathering element such as a photodiode or the like. As shown in Figs. 3 and 4, the optical head moving mechanism 48 is constructed from a motor 48a capable of forward/reverse rotation, a worm gear 48b which is rotated by the motor 48a, a worm wheel 48c which meshes with the worm gear 48b, a rack gear 48d which meshes with the worm wheel 48c, a slider 48e which is fixed to the rack gear 48d, a guide rod 48g which regulates the direction of movement of the slider 48e, and a head support (pick-up base) 48f which is integrally formed with the slider 48e, with the head support 48f being provided with the optical head 47. Further, the worm gear 48b and the guide rod 48g are arranged so that their lenghtwise directions are directed roughly parallel to the forward and backward direction of the disc drive 1A. In this type of optical head moving mechanism 48, if the worm gear 48b is rotated in a prescribed direction by the motor 48a, this rotation is transmitted through the worm wheel and the rack gear to the slider 48e, and this force causes the slider 48e to move along the guide rod 48g in the forward-backward direction of the disc drive 1A, whereby the optical head 47 fixed to the head support 48f is moved in the radial direction of the optical disc 3 loaded on the disc tray 5. In this construction, the optical head 47 and the optical head moving mechanism 48 form a playback or playback and recording means. Further, the operations of the spindle motor, motor 48 and motor 51 (described below) are controlled by a control means (CPU) provided in the circuit substrate assembly (not shown in the drawings). As shown in Figs. 3 and 4, a cam mechanism 50 which can be moved between the first position (Fig. 3) and a second position (Fig. 3) is provided in front of the mechanism unit 42, and this cam mechanism is operatively coupled with the mechanism unit 42 to displace the mechanism unit 42 between a lowered position (Fig. 3) and a raised position (Fig. 4). Namely, the cam mechanism 50 can be operated to move the mechanism unit 42 to either the lowered position when the cam mechanism is in the first position shown in Fig. 3, or the raised position when the cam mechanism is in the second position shown in Fig. 4. In more details, as shown in Figs. 7 and 8, the cam mechanism 50 includes a cam member 55 arranged so as to be slidable between the first position (Fig. 7) and a second position (Fig. 8) in the sideways direction with respect to the chassis 40 (i. e., the horizontal direction orthogonal to the direction movement of the disc tray 5). The cam member 55 is constructed from a roughly plate-shaped horizontal portion 55a and a plate-shaped vertical portion 55b which is integrally formed with one lengthwise edge of the horizontal portion 55a so as to make a structure having a roughly L-shaped cross section. Formed on the horizontal portion 55a of the cam member 55 are sideways guide grooves 56a, 56b which engage respectively with a pair of protrusions 52a, 52b which protrude from the top of the front portion of the chassis 40. Further, the underside surface of the horizontal portion 55a is provided with an engaging pin 57 which is inserted into an elongated slot formed in the top of the front portion of the chassis 40. This engaging pin 57 is adapted to engage with an emergency eject mechanism (described below). Further, the vertical portion 55b of the cam member 55 is positioned to face the front wall which defines the opening 41 of the chassis 40. Formed in the vertical portion 55b are a pair of cam grooves 58a, 58b each having the same shape. Each of the cam grooves 58a, 58b is constructed from a horizontally extending upper groove 581 and a lower groove 583 and a slanting groove 582 which connects the upper groove 581 and the lower groove 583. Further, the guide pins (following members) 43a, 43b adapted for insertion into the cam grooves 58a, 58b, respectively, are provided on the front surface of the base frame 43 of the mechanism unit 42 as described above. In this way, when the cam member 55 is moved between the first position and the second position, the guide pins 43a, 43b are moved by the slide abutment with the cam grooves 58a, 58b in the up and down direction. Namely, when the cam member 55 is positioned at the first position, the guide pins 43a, 43b are engaged with the lower grooves 583 (Fig. 7), and the front portion of the mechanism unit 42 is in the lowered position shown in Fig. 3. When the cam member 55 is moved from the first position to the second position, the guide pins 43a, 43b move up by the slanting grooves 582, thereby causing the front portion of the mechanism unit 42 to move from the lowered position toward the raised position. Then, when the cam member 55 reaches the second position, the guide pins 43a, 43b engage with the upper grooves 581 (Fig. 8), and the front portion of the mechanism unit 42 is displaced to the raised position shown in Fig. 4. Further, a protrusion 59 is integrally formed on an end portion of the horizontal member 55a of the cam member 55 to engage with the cam member movement restricting groove 7 formed in the underside surface of the disc tray 5. As a result, the protrusion 59 is engaged with the first movement restricting groove 7a of the disc tray 5 and is thereby prevented from moving in the sideways direction, whereby the cam member is held at the first position. Then, in accordance with the movement of the disc tray 5, the protrusion 59 slides from the first movement restricting groove 7a to the second movement restricting groove 7b, and upon moving through this slanting groove, the cam member 55 is displaced within the range of the lower grooves 583 of the cam grooves 58a, 58b of the cam member 55. Then, when the protrusion 59 reaches the position of the third movement restricting groove 7c, the cam member 55 moves toward the second position. Further, the cam mechanism 50 and a drive mechanism 60 for moving the disc tray 5 are provided in the front portion of the mechanism unit 42 of the chassis 40. As shown in Figs. 7 and 8, the drive mechanism 60 includes a loading motor 61 capable of forward/reverse rotation provided in the underside surface of the front portion of the chassis 40, a pinion gear 62 is mounted on a rotation axis 61a of the motor 61, a medium-diameter second gear 63 which meshes with the pinion gear 62, and a large-diameter third gear 64 which meshes with a small gear (not shown in the drawings) fixed coaxially below the second gear 63. Further, a small-diameter cylindrical portion is integrally formed on top of the third gear 64 so as to be coaxial therewith, with a small gear 64a being integrally formed on top of this cylindrical portion so as to be coaxially therewith. Meshing with the small gear 64a of the third gear 64 is an operative gear 65 which meshes with the first and second racks 6a, 6b of the disc tray 5. Namely, the operative gear 65 includes a lower gear 65a which meshes with the small gear 64a of the third gear 64, and an upper gear 65b which meshes with the rack 6 of the disc tray 5, in which the upper gear 65b being integrally formed on the same axis as the lower gear 65a. In the present embodiment, the gears 62-65 are flat teeth gears, which constitute a rotational speed reduction mechanism for the motor 61. The operative gear 65 is provided so as to be capable of rotation on a rotation axis 67 provided on a planetary arm 66 mounted to a rotation axis 64b of the third gear 64. The planetary arm 66 includes a rotation portion 66a which is rotatably fitted onto the cylindrical portion of the third gear 64, and the first and second arms 66b, 66c which extend from the rotation portion 66a, so that the whole of the planetary arm 66 has a roughly v-shaped structure. One end of the first arm 66b of the planetary arm 66 is provided with the protruding rotation axis 67 to which the operative gear 65 is rotatably mounted. Namely, the operative gear 65 rotates about the axis 67 of the first arm 66b which functions as a rotation axis thereof as well as the operative gear 65 also turns around the axis 64b which functions as a revolution axis, so that the operative gear 65 functions as a planetary gear which can be turned around the axis 64b along the second rack 6b with being rotated about the axis 67. In this planetary gear mechanism, the operative gear 65 acts as a planet gear and the small gear 64a of the third gear 64 acts as a sun gear. Further, the end of the second arm 66c of the planetary arm 66 is provided with a pin 68 which protrudes downward into an engaging portion formed in the cam member 55. In this connection, as shown in Figs. 7 and 8, one part of the rotation portion 66a of the planetary arm 66 is partially cut away to expose the small gear 64a of the third gear 64 in order to enable the lower gear 65a of the operative gear 65 to mesh with the small gear 64a of the third gear 64. In this structure, the operative gear 65 carries out a first operation when engaged with the first rack 6a of the disc tray 5, in which the disc tray 5 is moved between the disc ejected position and the disc loaded position with the cam mechanism 50 being held at a prescribed position, and a second operation when engaged with the second rack 6b of the disc tray 5, in which the cam mechanism is moved between the first position and the second position. Namely, while the protrusion 59 provided on the top of the horizontal portion 55a of the cam member 55 is in engagement with the first movement restricting groove 7a in the underside surface of the disc tray 5, the movement of the cam member 55 from the first position to the second position is restricted. Accordingly, during such time, in other words during the time that the disc tray 5 is moving between the ejected position and the loaded position, the pin 68 of the second arm 66c of the planetary arm 66 is engaged with the engagement portion 55c of the cam member 55, thereby making it impossible for the planetary arm 66 to be turned around the axis 64b. As a result, the operative gear 65 is held at a prescribed position while the protrusion 59 of the cam member 55 is engaged with the first movement restricting groove 7a of the disc tray 5. In this state, as shown by the dashed line in Fig. 3, the operative gear 65 engages with the first linear rack 6a of the disc tray 5, whereby the disc tray 5 is moved from the disc ejected position to the disc loaded position by means of the rotation of the operative gear according to the rotation of the motor 61, and in this way the operative gear 65 functions as a driving gear for moving the disc tray 5. On the other hand, when the disc tray 5 moves accordingly to a position just before the disc loaded position, the protrusion 59 of the cam member 55 moves from the first movement restricting groove 7a to the second movement restricting groove 7b of the disc tray 5, and this causes the cam member 55 to be displaced by a small amount. Then, the disc tray 5 moves further, and when abutting portions 5d, 5e of the disc tray 5 come into abutment with the wall portions 40b of the chassis 40 and thereby further movement of the disc tray 5 is restricted, the protrusion 59 reaches the third movement restricting groove 7c, whereby the cam member 55 is able to move from the first position to the second position. In this state, as shown by the dashed line in Fig. 4, since the operative gear 65 engages with the arc-shaped second rack 6b and the cam member 55 is able to move to the second position and therefore the planetary arm 66 can be turned around the axis 64b, the operative gear 65 moves along the arc-shaped second rack 6b in accordance with the rotation of the motor 61. In accordance with such a turning movement of the operative gear 65, the planetary arm 66 rotates clockwise around the common axis 64b from the position shown in Fig. 7 to the position shown in Fig. 8, which in turn causes the second arm 66c of the planetary arm 66 to rotate in the same direction. In accordance with this rotation of the second arm 66c, the cam member 55 is driven by means of the pin 68 coupled with the engaging portion 55c and moves from the first position shown in Fig. 7 toward the second position shown in Fig. 8. In accordance with this movement of the cam member 55 from the first position toward the second position, the front guide pins 43a, 43b of the base frame 43 of the mechanism unit 42 rise up along the slanting grooves 582, whereby the front portion of the mechanism unit 42 is displaced from the lowered position shown in Fig. 3 to the raised position shown in Fig. 4. Further, a disc clamp 80 is provided on the upper portion of the chassis 40, and as shown in Fig. 9, the disc clamp 80 is supported for rotation by a plate-shaped support member 81 having a central opening 81a. In particular, the support member 81 is fastened at both ends with bosses (or rivets) to mounting portions 40c of the chassis 40 so as to secure the support member 81 to the chassis 40 in the side-ways direction. On the other hand, the disc clamp 80 is formed from a flat drum-shaped main body 80a having a bottom portion that is inserted into the opening 81a of the support member 81, and a flange portion 80b which is formed around the upper circumferential portion of the main body 80a. The flange portion 80b is adapted to abut the top of the support member 81. Further, an annular steel attraction member is provided inside the main body 80a and is adapted to be pulled by the permanent magnet provided in the turntable 46. Further, the disc drive 1A is equipped with an emergency eject mechanism 70 which enables the disc tray 5 to be manually moved forward to eject the optical disc 3 when the optical disc 3 stops rotating due to a power outage, for example, when the optical disc 3 is being rotated for playback. As shown in Figs. 3 and 4, the emergency eject mechanism 70 is arranged in the front portion of the chassis 40 and is constructed from a lever 71 which is provided in a rotatable manner on the side of the drive mechanism 60. The lever 71 is a roughly L-shaped member which includes a central portion 71a fixed to a rotation axis 72, a cam member drive portion 71b which extends from the central portion 71a, and a push portion 71c which also extends from the central portion 71a so as to be roughly perpendicular to the extending direction of the drive portion 71b. The front end of the cam member drive portion 71b meshes with an engagement pin 57 formed on the underside surface of the horizontal portion 55a of the cam member 55, and the tip of the push portion 71c is provided with a jig receiving portion for receiving a jig (not shown in the drawings) which is to be inserted through an aperture formed in the front panel 13. With the emergency eject mechanism 70 constructed in this way, if the cam member 55 is moved from the first position shown in Fig. 7 (Fig. 3) to the second position shown in Fig. 8 (Fig. 4), the engagement pin 57 formed on the underside of the horizontal portion 55a of the cam member 55 pushes the cam member drive portion 71b, thereby rotating the lever 71 to the position shown in Fig. 4. Now, in the case where a power outage occurs in this condition, the motor 61 of the drive mechanism stops operating, and this causes the mechanism unit 42 to stay at the raised position, thereby making it impossible to electronically eject the optical disc 3. In such case, a slender rod-shaped jig is inserted through the aperture formed in the front panel 13 of the disc drive 1A, with the tip of the jig coming into contact with the jig receiving portion 71c of the lever 71, and then in this state the jig is manually pushed further inward. When this is done, the lever 71 rotates in the counterclockwise direction about the rotation axis 72 from the position shown in Fig. 4, in accordance with such rotation, the cam member drive portion 71b pushes the engagement pin 57 of the cam member 55 in the sideways direction, and as a result, the cam member 55 is moved from the second position (Fig. 8) to the first position (Fig. 7). Accordingly the mechanism unit 42 also moves from the raised position (Fig. 4) to the lowered position (Fig. 3), thereby removing the optical disc 3 from the turntable 46 and causing the disc tray 5 to slightly protrude out of the aperture 13a of the front panel 13. In this state, the operative gear 65 of the drive mechanism 60 engages with the first rack 6a of the disc tray 5, thereby making it possible to grasp the protruding portion and manually pull the disc tray 5 out through the aperture 13a of the front panel 13. Next, the description of the operation of the disc drive 1A will be given. When the disc drive 1A is not in use, the empty disc tray 5 is housed inside the casing 10 (inside the main body 2) at the disc loaded position. In this state, as shown in Fig. 4, the mechanism unit 42 is in the raised position, the cam member 55 is in the second position, and the protrusion 59 of the horizontal portion 55a of the cam member 55 is in the third movement restriction groove 7c. Further, as shown by the dashed lines in Fig. 4, the operative gear 65 of the drive mechanism 60 meshes an end portion of the second rack 6b of the underside surface of the disc tray 5 which is far away from the first rack 6a thereof. Now, if an eject operation is carried out, the motor 61 will rotate in the prescribed direction, whereby the operative gear 65 is caused to rotate, by means of a rotational speed reduction mechanism. In this state, the operative gear 65 functions as a planetary gear which can be turned around the revolution axis 64b, and in accordance with this revolution, the operative gear 65 moves along the second rack 6b toward the first rack 6a. In accordance with the revolution of the operative gear 65, the planetary arm 66 rotates in the counterclockwise direction about the common axis 64b. In accordance with the rotation of the planetary arm 66, the second arm 66c causes the cam member 55 to move, via the pin 68, from the second position shown in Fig. 4 (Fig. 8) to the first position shown in Fig. 3 (Fig. 7), whereby the mechanism unit 42 is also moved from the raised position to the lowered position. In this case, while the cam member 55 is moving from the second position to the first position, the protrusion 59 on top of the horizontal portion 55a of the cam member 55 slides along the third movement restricting groove 7c, and reaches the first movement restricting groove 7a via the second movement restricting groove 7b. At that point, the operative gear 65 moves from the arc-shaped second rack 6b to the linear first rack 6a, and the protrusion 59 of the cam member 55 also moves from the second movement restricting groove 7b to the first movement restricting groove 7a. When the protrusion 59 of the cam member 55 is moved to the first movement restriction groove 7a, the cam member 55 is restricted from moving in the sideways direction, so that the rotation of the planetary arm 66 is also restricted. In this state, the operative gear 65 acts as a driving gear to drive the disc tray 5 at that position. As a result, as shown by the dashed line in Fig. 3, the operative gear 65 engages with the first rack 6a of the disc tray 5, whereby the disc tray 5 is moved from the loaded position to the eject position according to the rotation of the motor 61. In this state, the mechanism unit 42 is displaced to the lowered position at the prescribed spacing from the disc clamp 80. Accordingly, the disc clamp 80 and the turntable 46 do not hinder the eject operation of the disc tray 5. Now, if a loading operation is carried out by placing the optical disc 3 into the disc supporting portion 5a of the disc tray 5 which is ejected to the outside through the aperture 13a of the front panel 13, the motor 61 will rotate in the opposite direction (i. e., the direction opposite that described above), thereby causing the operative gear 65 to rotate, via the rotational speed reduction mechanism, in the counterclockwise direction (i. e., reverse direction) shown in Fig. 3. Accordingly, the disc tray 5 moves backward (toward the rear of the disc drive) through the aperture 13a to the disc loaded position. In this way, the optical disc 3, which is supported at the prescribed position on top of the disc tray 5, will also be transported to the disc loaded position inside the main body 2. During the loading of the disc tray 5, namely while the disc tray 5 is moving backward, the operative gear 65 engages with the first rack 6a on the underside surface of the disc tray 5, and the protrusion 59 of the cam member 55 is guided along the first movement restriction groove 7a. Accordingly, the cam member 55 is held at the first position, and is therefore unable to move to the second position. Consequently, the planetary arm 66 is held at prescribed position so as to be unable to rotate. In this case, the operative gear 65 rotates at such a position, so that it functions as a driving gear for driving the disc tray 5. Further, in this state, the front portion of the mechanism unit 42 is held at the lower position. When the disc tray 5 approaches the disc loaded position, the protrusion 59 formed on the cam member 55 moves from the first movement restriction groove 7a to the second movement restriction groove 7b, thereby causing the cam member 55 to move slightly in the sideways direction. Then, when the disc tray 5 reaches the disc loaded position, abutment portions 5d, 5e provided on the rear portion of the disc tray 5 abut the wall portion 40b of the chassis 40, thereby restricting any further movement of the disc tray 5. In this state, the protrusion 59 of the cam member 55 moves to the third movement restriction groove 7b via the second movement restriction groove 7b, thereby enabling the cam member 55 to move from the first position to the second position, which in turn also makes it possible for the planetary arm 66 to rotate. In this state, the operative gear 65 moves from the first rack 6a to the second rack 6b. As a result, in this state, because the movement of the disc tray 5 is restricted while the planetary arm 66 is capable of revolution, if the operative gear 65 is rotated by the motor 61, the operative gear 65 moves and turns along the arc-shaped second rack 6b around the axis 64b. Therefore, in this state, the operative gear 65 functions as a planetary gear. When the operative gear 65 functions as a planetary gear and moves along the arc-shaped second rack 6b as described above, the planetary arm 66 also rotates in accordance with the movement of the operative gear 65, around the common axis 64b in the clockwise direction shown in Fig. 3. When the planetary arm 65 rotates in this way, the second arm 66c of the planetary arm 66 also rotates in the same manner in the clockwise direction, thereby causing the cam member 55 to move from the first position to the second position. In accordance with the movement of the cam member 55, the guide pins 43a, 43b of the front end of the base frame 43 of the mechanism unit 42 slide along the slanting grooves 582 of the cam grooves 58a, 58b and move upward to the upper grooves 581. Accordingly, the mechanism unit 42 is displaced from the lowered position to the raised position, whereby the central hole 3a of the optical disc loaded on the disc tray 5 engages with the center hub 46a of the turntable 46. Then, by means of the pulling force which acts on the disc clamp 80 by means of the permanent magnet of the turntable 46, the optical disc 3 is sandwiched between the turntable 46 and the disc clamp 80. In this state, if an operation such as a playback operation is carried out, the spindle motor is operated to rotate the turntable 46 in prescribed speeds, thereby making it possible to playback the optical disc 3. In this case, if the optical disc 3 is rotated at a high rate of speed (such as 8-times speed or 12-times speed), the optical disc 3 may undergo eccentric rotation due to eccentricity of the optical disc or dimensional error, and as explained previously above, this leads to the generation of vibrations. However, in this embodiment, the turntable 46 is provided on the support member 44 which is supported by the base frame 43 of the mechanism unit 42 via the elastic members 441. Further, the support member 44 is supported at three locations, namely at a central portion and both front corner portions. In other words, the arrangement of the elastic members forms a rough isosceles triangle, with the turntable positioned inside such triangular arrangement. As a result, if vibrations due to eccentric rotation of the optical disc 3 occur in the horizontal direction, the support member 44 will be displaced in the horizontal direction about the elastic member 441 at the rear central portion of the support member 44, whereby the elastic members 441 provided at the front corner positions of the support member 44 are able to absorb such displacement. Accordingly, by supporting the support member 44 on which the turn table 46 is provided at the three points described above, the disc drive 1A becomes highly effective at absorbing vibrations due to high speed rotation of the optical disc 3, and this is accomplished without having to provide a separate special vibration dampening means. As a result, the disc drive 1A is highly effective at preventing the transmission of vibrations generated due to high speed rotation of the optical disc 3 from reaching the base frame 43, the chassis 40, the casing 10 and the like. In particular, in the embodiment described above, the drive mechanism 60 of the disc tray 5 and the cam mechanism 50 are all housed inside the space in the front of the mechanism unit 42 inside the chassis 40. Consequently, a sufficient amount of space is created on the left and right sides of the mechanism unit 42, and this makes it possible for the base frame 43 of the mechanism unit 42 and the support member 44 to be formed with sufficient widths. Consequently, out of the various possible arrangements, the particular arrangement of elastic members 441 placed at side positions of the turntable 46 make it possible to provide sufficient spacing between the elastic members 441, and in this respect it becomes possible to arrange the elastic members 441 at left and right side positions at the front of the turntable 46. Furthermore, such arrangement of elastic members 441 is particularly effective at preventing the transmission of vibrations due to rotation of the optical disc 3. Now, when playback is finished or when playback is stopped in order to switch to another disc, the eject button is pushed after operation of the playback switch (i. e., an operation to stop playback). When this is done, the operation described above for ejecting the disc tray 5 is carried out to eject the disc tray 5 on which the optical disc 3 is placed, to the outside of the main body 2. In the case where the motor 61 stops operating, such as during a power outage, the optical disc 3 is stuck in the loaded position. In such a case, a jig may be inserted through the insertion aperture of the front panel 13 of the disc drive 1A to push the push portion 71c of the lever 71 in order to rotate the lever 71. When this is done, the lever 71 rotates in the counterclockwise direction shown in Fig. 4, and in accordance with such rotation, the cam member drive member 71b is rotated in the same direction, whereby the cam member 55 is forcedly moved from the second position shown in Fig. 8 to the first position shown in Fig. 7, which at the same time causes the mechanism unit 42 to move from the raised position to the lowered position. As a result, the optical disc 3 is released from the clamped condition between the disc clamp 80 and the turntable 46 and returns to the disc supporting portion of the disc tray 5. In this state, the operative gear 65 also moves from the second rack 6b to the first rack 6a, and the protrusion 59 of the edge portion of the horizontal portion 55a of the cam member 55 moves from the third movement restriction groove 7c to the first movement restriction groove 7a via the second movement restriction groove 7b. Consequently, the disc tray 5 is forced to protrude out slightly from the aperture 13a of the front panel 13 of the disc drive 1A, whereby it becomes possible to grasp and manually pull the disc tray 5 outward to the eject position. Accordingly, in the above embodiment it is possible to easily eject the optical disc 3 even in the case where there is no electrical power during playback. In the above embodiment, when the mechanism unit 42 is raised and lowered (i. e., displaced between a raised position and a lowered position), the operative gear 65 engages with the second rack 6b so as to function as a planetary gear. In this respect, the arrangement for raising and lowering of the mechanism unit 42 in the disc drive 1A according to the present invention is not limited to the construction as described above. In the present invention, means for displacing the mechanism unit 42 from the lowered position to the raised position is particularly significant. Therefore, other mechanism can also be adopted for lowering the raised mechanism unit 42. For example, in the case where the operative gear 65 engages with the second rack 6b, it is possible to release such engagement for displacing the mechanism unit 42 at the raised position to the lowered position. As stated above, according to the disc drive, the operative gear 65 of the drive mechanism 60 acts not only as a driving gear for driving the disc tray 5 but also as a driving gear for driving the cam member 55 which displaces the mechanism unit 42 between the raised position and the lowered position, and such an operative gear 65 having the functions is accomodated within a limited space in the chassis 40 provided in front of the mechanism unit 42. Therefore, it is possible to simplify the structure of the disc drive in comparison with the prior art disc drive. Further, by employing such a part as the planetary arm 66 which supports the operative gear 65 rotatably and acts to move the cam member 55, the number of the parts required can be reduced and the assembly thereof can be made easy. Further, in the disc drive according to the present invention, the mechanism unit is constructed from the base frame and the support member on which the turntable or the like are provided, and the support member is supported on the base frame by means of three elastic members which are arranged at the left and right sides of the turntable and at the back side of the turntable. By such an arrangement of the elastic members, it is possible to effectively absorb vibrations generated by eccentric rotation of the optical disc, thereby enabling to prevent such vibrations from being transmitted to the base frame or the chassis. In particular, since the drive mechanism (loading mechanism) is accomodated in a limited space of the chassis in front of the mechanism unit, it is possible for the mechanism unit to have a sufficient width. As a result, it is possible to arrange the elastic members at the corner position of the base frame so as to have a sufficient distance therebetween at the right and left sides of the front of the turntable, and such an arrangement of the elastic members are particularly effective for absorbing the vibrations.

Claims: A disc drive (1A) comprising: a main body (2) having a chassis (40); a base frame (43) having a front portion and a rear portion, said rear portion being pivotally supported on said chassis (40) such that said front portion is displaceable between a raised position in which a disc (3) can be reproduced and a lowered position which is lower than the raised position; a support member (44) having a turntable (46), on which a disc (3) is to be placed and a pick-up (47), said support member (44) having a rear portion and a front portion including two front side portions; elastic members (441) provided between the support member (44) and the base frame (43) for elastically supporting the support member (44) with respect to the base frame (44), and a displacing mechanism (50, 60) which is operatively associated with said base frame (43) so as to displace said base frame (43) between said raised position and said lowered position; characterized in that three elastic members (441) being provided and arranged substantially at the two front side portions and at a substantially middle part of the rear portion of the support member (44) to form a rough isosceles triangle, whereby said turntable (46) is located inside said triangle closer to a line passing through the two elastic members (441) disposed at the front side portions, than to the elastic member (441) at the rear portion wherein when vibration is caused due to eccentric rotation of the disc by the turntable (46), the support member (44) could be displaced about the elastic member (441) at the rear portion but the elastic members (441) at the two front side portions act to damp the displacement. The disc drive as claimed in claim 1, wherein said base frame (43) has a roughly rectangular shape and said support member (44) is arranged inside the base frame (43). The disc drive as claimed in claim 2, wherein each of said elastic members (441) is formed into a roughly cylindrical shape having an upper portion engaged with the support member (44) and a lower portion engaged with the base frame (43). The disc drive as claimed in claim 3, wherein each of the cylindrical shape elastic members (441) is used in an erected state for connecting the base frame (43) and the support member (44) so as to be flexible in every direction.

Inventors: FURUKAWA KEN ICHI, FURUKAWA, KEN'ICHI
Applicants: MITSUMI ELECTRIC CO, MITSUMI ELECTRIC COMPANY LTD.
Application year: 1997
Main classification: G11B17
IPC codes: G11B33, G11B17