Patent Publication Number: US-6219314-B1

Title: Disc changer with rotatable disc support and disc player including the disc changer

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a disc changer for bringing disc-shaped information carriers into and out of a position, which disc changer comprises a supporting body and a disc-shaped disc support, which is supported by the supporting body, is arranged to be movable relative to said body, and is rotatable about an axis of rotation, which disc support has supporting surfaces for said information carriers and further comprises a first toothed ring which extends around said axis of rotation and is not rotatable relative to the disc support, which toothed ring is adapted to cooperate with a second toothed ring which extends around an axis of the supporting body, which axis of the supporting body extends parallel to and at a distance from the axis of rotation, means being provided for rotating and guiding the disc support. 
     The invention further relates to a disc player comprising a scanning device having means for inscribing and/or reading disc-shaped information carriers and further having a turntable which is rotatable about an axis of rotation, for supporting an information carrier which is in a scanning position, and a disc changer for moving said information carriers into and out of the position related to the scanning position. 
     A disc player with an integrated disc changer is known from JP-A 5-182337. The known player has a housing and a drawer which is movable into and out of the housing and is supported in the frame, which drawer is constructed as a disc changer. The housing accommodates a scanning device with an optical unit for scanning a Compact Disc and a turntable for supporting and rotating the Compact Disc. The drawer has a supporting body carrying a disc-shaped disc support with three supporting surfaces for Compact Discs. The disc support has a peripheral edge whose shape differs from a circular shape and having three flattened edge portions which extend from one supporting surface to another supporting surface. The disc changer thus formed is rotatable relative to the supporting body. For this purpose the drawer has a toothed driving wheel in mesh with a toothed ring of the disc support, a rotatable guide disc with an eccentric guide shaft and fixed guide walls. The toothed driving wheel and the guide disc, which is freely rotatable relative to the toothed wheel, are both rotatable about a common shaft which is fixed relative to the supporting body. The eccentric guide shaft extends through a central opening in the disc support, the guide walls cooperating with the peripheral edge of the disc support. A disadvantage of the known disc changer is that it requires a comparatively large number of parts to realise the desired movements of the disc support. Moreover, the comparatively large toothed driving wheel occupies much space, which is undesirable in modern compact equipment. The guide walls needed in the known disc changer serve to keep the disc changer in a desired path during rotation and in desired end positions in a condition of rest. A disadvantage of the construction using a toothed driving wheel and a freely rotatable guide disc is that despite the fixed guide walls no accurately defined end positions are possible owing to the possibility of rotation of the toothed wheel and the guide disc relative to one another and the presence of play between the peripheral edge of the disc support and the fixed guide walls. In the known disc player the end positions are detected by detection means, as disclosed in JP-A 5-182339. Another disadvantage of the guide construction used in the known disc changer is that rotation of the disc support produces relatively much noise and the play in the end positions of the disc changer is so large that the disc support is movable over a considerable range. 
     SUMMARY OF THE INVENTION 
     It is one of the objects of the invention to provide a compact disc changer of the type defined in the opening paragraph, having simple means for a well-defined movement of the disc support and for maintaining the disc support in well-defined positions. 
     The disc changer in accordance with the invention is characterised in that the second toothed ring is a toothed ring which is not rotatable relative to the disc support and which is in mesh with the first toothed ring of the disc support, said means for rotating and guiding the disc support comprising a drive member which is rotatable about said axis of the supporting body, to which drive member the disc support is rotatably connected at the location of the axis of rotation. This results in an at least substantially play-free construction. A further advantage of the disc changer in accordance with the invention is that the drive member used therein defines any position which can be occupied by the disc support, as a result of which the disc support can only perform well-defined movements and occupy well-defined positions. Another advantage is the small number of parts required to rotate and guide the disc support and to ensure stable positions of this support. 
     An embodiment of the disc changer in accordance with the invention is characterised in that the first toothed ring of the disc support has outer teeth and the second toothed ring of the supporting body has inner teeth. The principal advantage of this embodiment is that the disc changer can have a small overall height. 
     An embodiment of the disc changer in accordance with the invention is characterised in that the number of outer teeth is in a ratio of 3:4 to the number of inner teeth, the distance between the axis of rotation of the disc support and said axis of the supporting body being equal to half the difference between the pitch diameters of the two toothed rings. In this embodiment one revolution of the drive member produces one third revolution of the disc support in the opposite direction of rotation. In this embodiment the disc support preferably has three contiguous or substantially contiguous supporting surfaces, in which case the transverse dimensions of the disc support can be at least twice the diameter of the information discs to be supported. 
     An embodiment of the disc changer in accordance with the invention is characterised in that the first toothed ring has inner teeth and the second toothed ring has outer teeth, the number of inner teeth being in a ratio of 3:2 to the number of outer teeth, the distance between the axis of rotation of the disc support and said axis of the supporting body being equal to half the difference between the pitch diameters of the two toothed rings. An advantage of this embodiment, which is a variant of the preceding embodiment, is that one revolution of the drive member produces one third revolution of the disc support in the opposite direction of rotation. This embodiment is also suitable for supporting three disc-shaped information carriers on a disc support of minimal dimensions. 
     It is another object of the invention to provide a silent changer whose operation is accurate and which is yet of a simple construction. 
     The disc player in accordance with the invention comprises a scanning device having means for inscribing and/or reading disc-shaped information carriers and further having a turntable which is rotatable about an axis of rotation, for supporting an information carrier which is in a scanning position, and the disc changer in accordance with the invention, for moving said information carriers into and out of the position related to the scanning position. An advantage of the disc player in accordance with the invention is that in operation the disc support is moved silently and in a well-defined manner, information discs situated on the supporting surfaces being brought into well-defined positions relative to the scanning device. This results in an efficiently operating disc player, requiring only a short time to move an information disc to the turntable or to change an information disc to be scanned. The disc changer may be integrated in the disc player, the scanning device extending for example underneath the disc support and being supported in or relative to the supporting body, the scanning device and the disc support being movable towards and away from each other viewed along the axis of rotation. The information discs can simply be lowered onto the supporting surfaces of the disc support. 
     An embodiment of the disc player in accordance with the invention is characterised in that the supporting body of the disc changer forms part of a drawer which is movable into and out of a housing. In a slid-out position of the drawer two or three information discs can be placed onto and/or removed from the disc support depending on the extent to which the drawer has been pulled out. The drawer may also accommodate the scanning device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in more detail, by way of example, with reference to the drawings, in which 
     FIG. 1 is an exploded view showing an embodiment of the disc player in accordance with the invention, including an integrated first embodiment of the disc changer in accordance with the invention, 
     FIG. 2 is a perspective plan view of a part of the disc player shown in FIG. 1, 
     FIG. 3 is a perspective underneath view of a disc support forming part of the disc changer of the disc player shown in FIG. 1, 
     FIG. 4 is an underneath view of a drive member forming part of the disc changer of the disc player shown in FIG. 1, 
     FIG. 5 is a perspective plan view of a slide member forming part of the disc player shown in FIG. 1, 
     FIG. 6 is an underneath view of a command disc adapted to cooperate with the slide member of the disc player shown in FIG. 1, 
     FIG. 7 is a perspective underneath view of a disc support forming part of a second embodiment of the disc changer in accordance with the invention, 
     FIG. 8 is a perspective plan view of a supporting body forming part of the second embodiment, 
     FIG. 9 is a perspective plan view of a third embodiment of the disc changer in accordance with the invention, and 
     FIG. 10 shows the third embodiment in a partly cross-sectional view. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The embodiment of the disc player in accordance with the invention shown in FIGS. 1 to  6  comprises a frame  1  secured in a housing  1   a  and a drawer  3  which is movably supported relative to the frame. The frame  1  comprises a toothed rack  5  for cooperation with a toothed wheel  7  to move the drawer  3  into and out of the housing  1   a.  The frame further comprises two guideways  9  for cooperation with two guide rails  11  of the drawer  3 . The drawer  3  serves as a supporting body for a disc-shaped disc support  13  which is rotatable about an axis of rotation  13   a.  In the present example the disc support  13  has three supporting surfaces  15  for disc-shaped information carriers, such as CDs. A drive system  17  is secured to a side of the drawer  3  which is remote from the disc support  13 , i.e. the underside, which system comprises an electric motor  19 , a command disc  21  and a slide member  23 . The slide member  23  has four inclined grooves  25  engaged by four guide pins  27  of a chassis  29 . The chassis  29  carries a scanning device  33  via four suspension elements  31 . The scanning device  33  comprises a turntable  37 , which is rotatable about an axis of rotation  37   a  by means of an electric motor  35 , and an optical scanning unit  39 , which is radially movable relative to the turntable  37 . The optical scanning unit  39  comprises an objective lens  41  for focusing a scanning beam onto a scanning surface of an information disc. The scanning device  33  further comprises elements not shown in the drawings, such as a radiation source and a radiation-sensitive detector. 
     At its side  43  facing the drawer  3  the disc support  13  has a toothed ring  45 , also referred to as the first toothed ring  45 , which is concentric with the axis of rotation  13   a  and has outer teeth  45   a.  The drawer  3  has a substantially central opening  47  and has a toothed ring  51 , which is concentric with an axis  49  which extends through the opening  47 . The toothed ring  51 , also referred to as the second toothed ring  51 , has inner teeth  51   a.  A drive member  53 , which is rotatable about the axis  49 , is disposed in the opening  47 . The drive member  53  is supported in a mounting plate  55  of the drive system  17  and comprises a drive pin  53   a.  The drive pin  53   a  extends into or through a central opening  57  in the disc support  13 , the disc support being rotatable relative to the pin  53   a.  The drive pin  53   a  has a central axis which coincides with the axis of rotation  13   a.  In the assembled condition, which is the condition on which the entire description is based, the outer teeth  45   a  of the first toothed ring  45  are in mesh with the inner teeth  51   a  of the second toothed ring  51 . The number of outer teeth  45   a  is in a ratio of 3:4 to the number of inner teeth  51   a.  The axis of rotation  13   a  of the disc support  13  is situated at a distance d from the axis  49  of the drawer  3 , which distance d is equal to half the difference between the pitch diameters of the toothed rings  45  and  51 . In the present example both toothed rings  45  and  51  have straight teeth. It is taken to be common knowledge that pitch circles of two meshing toothed rings or, generally speaking, toothed wheels are imaginary circles which are in contact with one another and along which the toothed rings or wheels mesh with one another. In the present embodiment the number of outer teeth  45   a  is seventy-two and the number of inner teeth  51   a  is ninety-six. 
     The disc changer in accordance with the invention comprises an electric motor  59 , which is secured to the underside of the drawer  3  by means of a mounting plate  61 . The electric motor  59  is coupled to the driving wheel  7  via a belt/toothed-wheel transmission  63 , which driving heel is in mesh with the toothed rack  5  of the frame  1 . When the electric motor  59  is energised the drawer  3  can be translated relative to the frame  1  as indicated by the double arrow x, to move the disc support  13  into or out of the housing  1   a.    
     A belt/toothed-wheel transmission  65  couples said electric motor  19  to a toothed wheel  21   a  of the command disc  21 . Along a part of its circumference the command disc  21  has teeth  67  for cooperation with teeth  69  of the drive member  53 . At one side  71 , i.e. the underside, the command disc  21  carries a triangular drive profile  73 , which engages in a rectangular opening  75  in the slide member  23 . The drive profile  73  has three outer walls  73   a,    73   b  and  73   c  for cooperation with the inner walls  23   a  which bound the opening  75  in the slide member  23 . These elements are arranged and dimensioned in such a manner that in the case of an information disc which is in a scanning position, i.e. which is situated on the turntable  37 , energisation of the electric motor  19  causes the slide member  3  to be moved in a direction x 1  relative to the mounting plate  17  in order to move the scanning device  33  in a direction y 1  which is oriented transversely thereto. After this movement the information disc initially situated on the turntable  37  will be situated on one of the supporting surfaces  15  of the disc support  13 . When the energisation of the electric motor  19  continues the teeth  67  of the command disc  21  come into mesh with the teeth  69  of the drive member  53  and the drive member  53  is rotated about the axis  49 , the drive member  53  making exactly one revolution during meshing. During this revolution the disc support  13  is moved and is rotated through and angle of 120° about the axis of rotation  13   a.  In the position of the disc support  13  then reached another supporting surface  15  is again in register with the turntable  37 . When the energisation of the electric motor  19  continues the slide member  23  is moved in a direction x 2 , the scanning device  33  being guided so as to move in a direction y 2 . During the last-mentioned movement an information disc lying on the supporting surface  15  of the disc support  13  which is in register with the turntable  37  is lifted by the turntable  37  to bring the information disc in the scanning position. The above cycle is repeated when the energisation of the electric motor  19  is continued. The drive member  53  and the scanning device  33  are thus driven and moved intermittently. 
     It is to be noted that the present disc player comprises a disc-pressure device  77  with a disc pressure member  79  for clamping an information disc onto the turntable  37  in the scanning position. 
     The embodiment of the disc changer in accordance with the invention shown in FIGS. 7 and 8 can accept a maximum of three optically scanned disc-shaped information carriers. For this purpose, the changer has three supporting surfaces  215  provided on a disc support  213 . The disc support  213  is arranged on a supporting body  203  with an imaginary axis  249   c  and is rotatable relative to the body  203  about an axis of rotation  213   a,  which extends parallel to the axis  249  and can rotate around this axis  249 . 
     Similarly to the disc changer used in the disc player shown in FIGS. 1 to  6  the present disc changer comprises a drive member which is rotatable about the axis  249  of the supporting body  203  and which is rotatably coupled to the disc support  13  at the location of the axis of rotation  213   a.  The disc support  213  itself has a first toothed ring  245 , which is concentric with the axis of rotation  245  and which has inner teeth  245   a,  which mesh with outer teeth  251   a  of a second toothed ring  251 , which forms part of the supporting body  203  and is concentric with the axis  249 . The ratio between the number of inner teeth  245   a  and the number of outer teeth  251   a  is 3:2. The axis of rotation  213   a  and the axis  249  are situated at a distance d from one another, which distance is equal to the difference between the pitch radii of the toothed rings  245  and  251 . The disc changer operates in the same way as the changer already described. In the case of said ratio the disc support of the disc changer shown in FIGS. 7 and 8 particularly performs one third revolution about the moving axis of rotation  213   a  for one revolution of the drive member, as a result of which the disc support assumes accurately pre-defined positions, only a limited area being required to perform the movements between the positions. 
     The embodiment of the disc changer in accordance with the invention shown in FIGS. 9 and 10 is intended for bringing disc-shaped information carriers such as CDs or CD-ROMs into or out of positions related to a scanning position. the disc changer comprises a supporting body  303 , for example in the form of a plate-shaped frame which may be mounted in a housing, and a disc-shaped disc support  313  supported by the supporting body  303 . The disc support  313  has three supporting surfaces  315 , which are each adapted to support an information disc and which are arranged in such a manner relative to one another that the disc support has minimal radial dimensions. The disc support  313  is rotatable about an axis of rotation  313   a  relative to the supporting body  303  and can be translated in a plane transverse to the axis of rotation  313   a.  The disc changer further comprises a drive member  353 , which is rotatably coupled to the disc support  313  at the location of the axis of rotation  313   a.  The drive member  353 , which serves for rotating and guiding the disc support  313 , is supported in the supporting body  303  is rotatable relative to this body about an axis  349  of the supporting body. The disc changer has two toothed rings, a first toothed ring  345  being fixedly secured to the disc support  313  and a second toothed ring  351  being fixedly secured to the supporting body  303 . The first toothed ring  345 , which has outer teeth, is situated within and is in mesh with the second toothed ring  351 , which has inner teeth. The first toothed ring  345  has a pitch circle p 1  and the second toothed ring  351  has a pitch circle p 2 . When the drive member  353  is rotated about the axis  349  in the direction r, the two pitch circles p 1  and p 2  roll in contact, the disc support  313  being moved and rotating in the direction R about the axis of rotation  313   a  which moves along with the disc support. 
     In order to achieve that the disc support  313  with the three supporting surfaces  315  revolves within a minimal space in a manner as described above, the first toothed ring  345  has in the present example fifty-seven teeth and the second toothed ring  351  has seventy-six teeth. The axis of rotation  313   a  is situated at a distance d from the axis  349 , which distance is equal to half the difference between the pitch diameters p 2  and p 1 . After one full revolution of the drive member  353  the disc support  313  has performed exactly one third revolution. It is obvious that different numbers of teeth may be chosen within the scope defined by the invention that the number of outer teeth should be in a ratio of 3:4 to the number of inner teeth. 
     The disc changer further comprises an electric motor  319  for driving the drive member  353 . A transmission mechanism  365 , in the present example a belt/toothed wheel transmission, couples the electric motor  319  to a toothed wheel  379  secured to the drive member  353 .