Abstract:
The invention relates to a changer apparatus for information discs, comprising
       a stacking unit for stacking at least two information discs in at least two stacking positions,   a read/write unit for reading information stored on the information discs and/or writing information on the information discs in a play position,
 
an eject position being provided in which an information disc can be removed from the apparatus,
 
In such a changer apparatus transport means have been provided for moving the information discs from the eject position into a loading position of the stacking unit along a curve-shaped loading path.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a changer apparatus for information discs, comprising
         a stacking unit for stacking at least two information discs in respective stacking positions,   a read/write unit for reading information stored on the information discs and/or writing information on the information discs when they are in a play position, an eject position being provided in which an information disc can be inserted and removed from the apparatus.       

   2. Description of the Related Art 
   Such a changer apparatus is known from EP 743 639 A2. This known changer apparatus comprises a stacking unit which is movable in a vertical direction. By means of two longitudinal guides an information disc can be translated from the eject position into the play position and into the stacking unit. The play position is situated between the eject position and the stacking unit, the center of the information discs stacked in the stacking unit being situated outside the circumference of the information disc which is in the play position. Such a changer apparatus has an overall depth which is at least 1.5 times as large as the information disc diameter. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide a different changer apparatus which can be realized with a smaller overall depth. 
   According to the invention this object is achieved in that transport means are provided for transport of the information discs from an eject position into a loading position of the stacking unit along a curve-shaped loading path. 
   A curve-shaped loading path is to be understood to mean that the loading path extends non-orthogonally with respect to the front side of the changer apparatus and, consequently, that between the eject position and the loading position the information discs perform a lateral relative movement parallel to the front side of the changer apparatus. Thus, a curve-shaped loading path also includes a linear loading path which extends obliquely with respect to the front side of the changer apparatus. 
   For the transport of the information discs each individual information disc is brought into the eject position, for example by hand by a user. This single information disc is then moved into the loading position of the stacking unit along the curve-shaped loading path with the aid of the transport means. The loading position of the stacking unit is the position into which the individual information discs are moved for the time being after the transport from the eject position into the stacking positions of the stacking unit. 
   The curve-shaped loading path provides a greater design freedom for the construction as regards the arrangement of the individual components of the changer apparatus. This is particularly favorable for automotive uses because the mounting space then available, particularly in the case of mounting in the dashboard of a motor vehicle, is limited. 
   By means of the curve-shaped loading path it is possible to realize an apparatus depth smaller than 1.5 times the information disc diameter. 
   An advantageous embodiment of the invention is characterized in that the play position has been provided between the eject position and the loading position. 
   When the play position lies between the eject position and the loading position an information disc can be transferred directly from the eject position into the play position without prior transport into the stacking unit. As a result of this, the changer apparatus can also be used as a single-information-disc playing apparatus. 
   A further advantageous embodiment of the invention is characterized in that the play position is offset from the direct connecting line between the loading position and the eject position. 
   For a compact construction of the changer apparatus the appropriate arrangement of the play position is very important because usually the play position should be arranged in such a manner that the center of the stacking unit is situated outside the perimeter of the information disc in the play position. 
   Particularly in the case of changer apparatus having an essentially square base, a play position which is offset from a direct connecting line between the eject position and the loading position enables a better space utilization of the available mounting space. Frequently, for mounting in the dashboard of a motor vehicle only a mounting space of 1 DIN, i.e. having a width of 178 mm, a depth of 155 mm and a height of 50.5 mm, is available, which can be utilized in an optimum manner with the offset arrangement of the play position. 
   A further advantageous embodiment of the invention is characterized in that the play position is disposed on the loading path. 
   When the play position is situated on the loading path, the same transport means can be used for the transport of the information disc between the eject position and the loading position as well as for the transport between the eject position and the play position and the transport between the play position and the loading position. No additional transport mechanism is needed for the transfer from the loading path into the play position. 
   A further advantageous embodiment of the invention is characterized in that a first transport mechanism is provided for the transport of the information discs between the eject position, the play position and the loading position, and a second transport mechanism is provided for the transport of the information discs into the stacking positions of the stacking unit, the first transport mechanism being adapted to move the information discs in the loading plane and the second transport mechanism being adapted to move the information discs in a stacking direction oriented vertically with respect to the loading plane. 
   Such a changer apparatus having two transport mechanisms which operate perpendicularly to one another can be realized simply and at low cost. 
   A further advantageous embodiment of the invention is characterized in that the first transport mechanism comprises at least a first and a second guide for the disc edge of the information disc, which guide is grooved and is movable in the loading plane, the second guide comprising at least one rotationally drivable first transport wheel. 
   For transport of the information disc the disc edge engages the grooves in the first and the second guide. The movable arrangement of the first and the second guide permits these guides to move in accordance with the outline of the information disc and thus guide the disc edge of the information disc in a flexible manner. The first and the second guide contact the information disc only at its edge, the signal storage area of the information disc not being in contact with the guides. This precludes possible damage to the surface of the information disc. The rotationally drivable first transport wheel exerts a force on the disc edge oriented in the loading plane and thus rolls the information disc into the apparatus for loading and out of the apparatus for unloading. 
   A further advantageous embodiment of the invention is characterized in
     that the first guide is a passive supporting guide,   there is provided a third guide comprising a second transport wheel,   there is further provided a passive supporting guide as a fourth guide,   the first, second, third and fourth guide each have pivotal arms which are   supported at one end and which are pivotable in the loading plane,   the first, second, third and fourth guide are each pre-loaded towards the curve-shaped loading path,   the first transport wheel is essentially adapted to move the information discs between the eject position and a transfer position and the second transport wheel is essentially adapted to move the information discs from the transfer position into the loading position.   

   With such an arrangement the curve-shaped loading path can be realized simply and at low cost. In the eject position the information disc is held by the first and the second guide. The information disc is the rolled into the apparatus along the curve-shaped loading path by rotation of the first transport wheel of the second guide. The first and the second guide are then pivoted in accordance with the outline of the information disc and are urged against the disc edge as a result of the pre-load which is directed towards the loading path. Subsequently, the information disc is essentially guided by the first and the second guide. The first transport wheel serves for moving the information disc between the eject position and the transfer position. In the transfer position the first transport wheel transfers the drive function to the second transport wheel, and the information disc is moved from the transfer position into the loading position by the second transport wheel. The transport from the loading position into the eject position proceeds in the reverse sequence, i.e. initially the information disc is moved into the transfer position by, in principle, the second transport wheel and subsequently it is moved from the transfer position into the eject position by the first transport wheel. At the location of the transfer position, depending on the transport direction of the information disc, either the pivotal arm of the second guide is pivoted away from the disc edge by means of the first transport wheel and the pivotal arm of the third guide is pivoted towards the disc edge by means of the second transport wheel, as a result of which the groove of the first transport wheel is disengaged from the disc edge and the groove of the second transport wheel engages with the disc edge, or in the opposite transport direction the pivotal arm of the second guide is pivoted towards the disc edge and the pivotal arm of the third guide is pivoted away from the disc edge in a corresponding manner. 
   The fourth guide, which serves as a passive supporting guide, is preferably arranged in a rearward zone of the changer apparatus and takes over the function of the first passive supporting guide in the course of the loading operation. The fourth guide can be arranged on the chassis plate or, alternatively, on the read unit. In a transitional phase both the first passive supporting guide and the fourth passive supporting guide engage with the disc edge of the information disc. 
   A further advantageous embodiment of the invention is characterized in that the first and the third guide are mounted on a common pivot. 
   Such a mounting on a common pivot enables the first and the second transport wheel to be driven by a single motor via an intermediate wheel which is rotatably mounted on the common pivot. 
   A further advantageous embodiment of the invention is characterized in that the read/write unit comprises a base plate and a laser mounting plate, the base plate and the laser mounting plate are coupled by means of dampers, the base plate is slidably mounted on the chassis plate, and the laser mounting plate carries a clamping device for clamping the information disc in the play position and an optical unit for reading information stored on the information disc. 
   Such a construction provides a proper isolation between the read/write unit and the chassis plate, so as to isolate the read/write unit from external vibrations and shocks. 
   This is particularly important when the CD changer apparatus is used in a motor vehicle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A diagrammatically represented embodiment of the invention will be described hereinafter, by way of example, with reference to  FIGS. 1 to 13  of the drawings. In the drawings: 
       FIG. 1  is a perspective view of a changer apparatus for information discs with an information disc in an eject position, in which it can be removed from the apparatus by hand by a user. The apparatus includes a read unit for reading information stored on the information disc, a stacking unit for stacking at least two information discs, and a first, second, third and fourth guides for transport of the information disc from the eject position into a play position and then into a loading position, 
       FIG. 2  is a front view of the changer apparatus in the eject position as shown in  FIG. 1 , 
       FIG. 3  is a perspective view of the read unit, 
       FIG. 4  is a perspective view of parts of the changer apparatus with a sliding plate for translating the read unit, not shown, and for controlling the pivotal movement of the first, the second, the third and the fourth guide as well as for controlling guide pins of the stacking unit and a clamping arm of the read unit, 
       FIG. 5 . is a side view of the changer apparatus in the eject position as shown in  FIG. 2 . 
       FIG. 6  is a plan view of the changer apparatus in the eject position as shown in  FIG. 1 , 
       FIG. 7  is a side view of the changer apparatus in a first intermediate position, in which the information disc is freely interposed between a clamping disc and a driving disc, from which first intermediate position the information disc is movable into the play position and into the loading position, 
       FIG. 8  is a side view of the changer apparatus in a second intermediate position, in which the information disc is clamped between the clamping disc and the driving disc of the read unit, 
       FIG. 9  is a plan view of the changer apparatus in the first intermediate position, the information disc being held by the first, the second, the third and the fourth guide, 
       FIG. 10  is a plan view of the changer apparatus in a play position, the first, the second, the third and the fourth guide being in positions pivoted away from the disc edge of the information disc, the information disc being clamped between the driving disc and the clamping disc of the read unit, and the information stored on the information disc being readable by means of the read unit, 
       FIG. 11  is a side view of the changer apparatus in the play position, 
       FIG. 12  is a plan view of the changer apparatus with an information disc in the loading position, and 
       FIG. 13  shows the changer apparatus of  FIG. 12  in a perspective view with an information disc in the loading position. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a perspective view of a changer apparatus for information discs with an information disc  1  in an eject position, in which it can be removed from the apparatus by hand by a user and in which it can be inserted into the apparatus by hand by the user for the purpose of loading. The information disc  1  has a circular disc edge  1   a  and a center hole  1   b . The changer apparatus is accommodated in a housing  2 , which is shown only partly and which has a base formed by a chassis plate  3 . The chassis plate  3  has a front edge  3   a , a rear edge  3   b , a left-hand side edge  3   c  and a right-hand side edge  3   d . The chassis plate  3  extends in an x-y plane, the x direction being defined as the direction from left to right in the same direction as the front edge  3   a  and the y direction being defined as a direction which extends in the same direction as the left-hand side edge  3   c . A direction perpendicular to the x-y plane is defined as the z direction. As is shown in the perspective view of  FIG. 1  a stacking unit  4  is arranged in the right-hand rear area of the housing  2 , which unit comprises a first threaded spindle  5 , a second threaded spindle  6  and a third threaded spindle  7 , which extend vertically with respect to the chassis plate  3  in the z direction. The first threaded spindle  5  has an external screwthread  5   a , the second threaded spindle  6  has an external screwthread  6   a  and the third threaded spindle  7  has a external screwthread  7   a . There is a first holder compartment  8 , a second holder compartment  9 , a third holder compartment  10 , a fourth holder compartment  11  and a fifth holder compartment  12 , which are arranged one above the other in the z direction and which serve for holding one information disc each. The first holder compartment  8  has a first opening  8   a , in which the external screwthread  5   a  of the first threaded spindle  5  engages, a second opening  8   b , in which the external screwthread  6   a  of the second threaded spindle  6  engages, and a third opening  8   c , in which the external screwthread  7   a  of the third threaded spindle  7  engages. Likewise, the second holder compartment  9 , the third holder compartment  10 , the fourth holder compartment  11  and the fifth holder compartment  12  each have three openings, not shown, in which the external screwthreads of the first threaded spindle  5 , the second threaded spindle  6  and the third threaded spindle  7  engage. By means of a gear train  60  comprising the gear wheels  60   a ,  60   b ,  60   c ,  60   d  and  60   e  the first threaded spindle  5 , the second threaded spindle  6  and the third threaded spindle  7  can be driven by a drive mechanism, not shown. Alternatively, driving by means of a toothed belt is possible. The holder compartments  8 ,  9 ,  10 ,  11  and  12  are movable in the vertical z direction by rotation of the threaded spindles  5 ,  6  and  7 . In the center of the stacking unit  4  an upper cover plate  61  carries an upper guide pin  62  and the chassis plate  3  carries a lower guide pin  63 . The upper guide pin  62  and the lower guide pin  63  can be moved in the z direction by means of a drive mechanism, not shown. 
   The operation of the stacking unit  4  will be explained hereinafter with reference to  FIG. 2 , which is a front view of the changer apparatus in the eject position as shown in  FIG. 1 . The third threaded spindle  7  and, likewise, the first threaded spindle  5  as well as the second threaded spindle  6 , which is not visible in  FIG. 2 , have an upper stacking zone  13 , a lower stacking zone  14  and a central stacking zone  15  between the upper stacking zone  13  and the lower stacking zone  14 . The central zone  15  has a vertical loading position  16 , which is spaced from the upper stacking zone  13  by an upper spacing zone  17  and which is spaced from the lower stacking zone  14  by a lower spacing zone  18 . The external screwthread  7   a  of then third threaded spindle  7  and, likewise, the external screwthreads  6   a  and  5   a  of the second threaded spindle  6  and the first threaded spindle  5 , respectively, have a pitch which is zero over an angle of rotation of 45°. In the upper spacing zone  17  and the lower spacing zone  18  the threaded spindles  5 ,  6  and  7  each have a pitch which is basically defined by the vertical height in the z direction of the holder compartments  8 ,  9 ,  10 ,  11  and  12 . The pitch of the threaded spindles  5 ,  6  and  7  in the upper spacing zone  17  and in the lower spacing zone  18  is substantially greater than the pitch in the loading position  16  and the pitch in the upper stacking zone  13  and the lower stacking zone  14 . In the representation shown in  FIG. 2  the first holder compartment  8  is in the loading position and the other holder compartments  9 ,  10 ,  11  and  12  are in the lower stacking zone  14 . The lower stacking zone  14  has a first stacking position  14   a , a second stacking position  14   b , a third stacking position  14   c  and a fourth stacking position  14   d . The upper stacking zone  13  has a first stacking position  13   a , a second stacking position  13   b , a third stacking position  13   c  and a fourth stacking position  13   d . In the representation shown in  FIG. 2  the second holder compartment  9  is in the first stacking position  14   a  of the lower stacking zone  14 , the third holder compartment  10  is in the second stacking position  14   b , the fourth holder compartment  11  is in the third stacking position  14   c , and the fifth holder compartment  12  is in the fourth stacking position  14   d . If starting from the situation represented in  FIG. 2  the threaded spindles  5 ,  6  and  7  are rotated, the first holder compartment  8 , which is in the loading position  16 , moves into the fourth stacking position  13   d  of the upper stacking zone  13 , the second holder compartment  9  moves into the loading position  16 , the third holder compartment  10  moves into the first stacking position  14   a , the fourth holder compartment  11  moves into the second stacking position  14   b  and the fifth holder compartment  12  moves into the third stacking position  14   c  of the lower stacking zone  14 . Likewise, the third holder compartment  10 , the fourth holder compartment  11  and the fifth holder compartment  12  can be moved into the stacking position  16  one after the other. Thus, by rotation of the threaded spindles  5 ,  6  and  7  each of the holder compartments  9 ,  10 ,  11  and  12  situated in the lower stacking zone  14  can be moved into loading position  16  one after the other and by further rotation the holder compartment  9 ,  10  and  11  can be moved into the upper stacking zone  13 . During the vertical travel of the holder compartments  8 ,  9 ,  10 ,  11  and  12  the information discs in these holder compartments are moved in the z direction by means of the upper guide pin  62  and the lower guide pin  63  in that the upper guide pin  62  and the lower guide pin  63  engage the center holes  1   b  of the information discs  1 . 
   Hereinafter, the changer apparatus is described further with reference to  FIG. 1 . For the transport of the information disc  1  from the eject position shown in  FIG. 1  into the first holder compartment  8 , which is in its loading position  16  as shown in  FIG. 2 , a first guide  20 , a second guide  21 , a third guide  22  and a fourth guide  23  have been provided. The first guide  20  is constructed as a passive supporting guide and by means of a pivotal arm  20   a  it is mounted so as to be pivotable about a pivot  20   b  on the left-hand side of the chassis plate  3 . The first guide  20  has a V-shaped groove  20   c  for guiding the disc edge  1   a  of the information disc  1 . The second guide  21  is arranged at the opposite side on the right-hand side of the housing  2  and comprises a first transport wheel  25 , which is supported on a pivotal arm  21   a  so as to be rotatable about a spindle  25   a . The pivotal arm  21   a  is mounted on the chassis plate  3  so as to be pivotable about a pivot  24 . For the transport of the information disc  1  the first transport wheel  25  has a V-shaped groove  25   b  adapted to engage with the disc edge  1   a  of the information disc  1 . The third guide  22  comprises a second transport wheel  26  which is supported on a pivotal arm  22   a  so as to be rotatable about a spindle  26   a . The pivotal arm  22   a  is supported on the chassis plate  1  on the same pivot  24  which carries the pivotal arm  21   a  of the second guide  21 . The second transport wheel  26  also has a V-shaped groove  26   b . The first transport wheel  25  and the second transport wheel  26  are rotationally drivable by means of a intermediate drive  27  comprising three intermediate wheels  27   a ,  27   b  and  27   c . The intermediate wheel  27   a  is rotatable about the spindle  24  and is driven by a motor, not shown, via a drive chain, not shown. The intermediate wheels  27   b  and  27   c  are rotatably supported on the pivotal arm  22   a.    
   The first guide  20 , the second guide  21 , the third guide  22  and the fourth guide  23  are each pre-loaded towards a curve-shaped loading path  28  by means of a spring, not shown. 
   In the eject position of the information disc  1 , which position is shown in  FIG. 1 , the first guide  20  and the first transport wheel  25  are urged against the disc edge  1   a  of the information disc  1  with the groove  20   c  and with the groove  25   b , respectively, under the influence of the spring-loads of the pivotal arms  20   a  and  21   a . The second transport wheel  26  of the third guide  22  is pressed away from the stacking unit  4  against the spring load, so that by rotation of the threaded spindles  5 ,  6  and  7  any one of the holder compartments  8 ,  9 ,  10 ,  11  and  12  can be moved into the loading position  16 . The transport wheel  26  is then pivoted away so far that any information discs present in the holder compartments  8 ,  9 ,  10 ,  11  and  12  are not touched by the second transport wheel  26 . 
   A read unit  30  is arranged so as to be movable on the chassis plate  3  in the front-left area of the changer apparatus. 
   The read unit  30  carries the fourth guide  23  which is constructed as a passive supporting guide and is mounted on the read unit  30  so as to be pivotable about a pivot  23   a . The fourth guide  23  has a V-shaped groove  23   b  for guiding the disc edge  1   a  of the information disc  1 . 
   The construction of the read unit  30  will be described in more detail hereinafter with reference to  FIG. 3 .  FIG. 3  is a perspective view of the read unit  30 . The read unit  30  has a base plate  31  comprising a first guide pin  31   a , a second guide pin  31   b  and a third guide pin  31   c . The base plate  31  is coupled to a laser mounting plate  35  by means of a first damper  32 , a second damper  33  and a third damper  34 . A clamping arm  36  with a clamping disc  37  is mounted on the laser mounting plate  35  so as to be rotatable about a clamping spindle  36   a . The laser mounting plate  35  supports a driving disc  38  which is rotationally drivable by means of a motor, not shown. Furthermore, an optical unit formed by a laser unit  39  is supported on the laser mounting plate  35  so as to be movable. The base plate  31  of the read unit  30  is mounted on the chassis plate  3  so as to be slidable. 
   To illustrate this slidable mounting of the base plate  31  on the chassis plate  3   FIG. 4  shows a perspective view of parts of the changer apparatus, the read unit  30 , the base plate  31  as well as the information disc  1  not being shown for the sake of clarity. 
   To guide the read unit  30 , as shown in  FIG. 4 , the chassis plate  3  carries a first guideway  40  and a second guideway  41 . The first guideway  40  serves for guiding the first guide pin  31   a  of the base plate  31  and the second guideway  41  serves for guiding the second guide pin  31   b . A sliding plate  43  is movable in the y direction by a drive mechanism, not shown. This sliding plate  43  comprises a first slider  44  having a V-shaped sliding slot  44   a , a second slider  45  having a V-shaped sliding slot  45   a , and a third slider  46  having a V-shaped sliding slot  46   a . The V-shaped sliding slot  44   a  serves for guiding the first guide pin  31   a  of the base plate  31 , the V-shaped sliding slot  45   a  serves for guiding the second guide pin  31   b  of the base plate  31 , and the V-shaped sliding slot  46   a  serves for guiding the third guide pin  31   c  of the base plate  31 . 
     FIG. 5  is a side view in the x direction showing the changer apparatus in the eject position of  FIG. 1 . As is apparent from  FIG. 1  the first guideway  40  and the second guideway  41  are L-shaped and thus comprise horizontal guideway sections  40   a  and  41   a  and vertical guideway sections  40   b  and  41   b.    
     FIG. 5  shows the clamping arm  36  with the clamping disc  37  in the open position, i.e. the clamping disc  37  does not bear on the driving disc  38 . 
   For the transport of the information disc  1  into the stacking unit  4  or into a play position, starting from the eject position shown in  FIG. 1 , the first transport wheel  25  is rotated by a drive unit, not shown, by means of the intermediate wheel  27   a , as a result of which the information disc  1 , supported by the first guide  20 , is rolled onto the curve-shaped loading path  28  into the apparatus. 
   At the same time, the sliding plate  43  shown in  FIG. 5  and, consequently, the read unit  30  is moved into the apparatus in the y direction. The first guide pin  31   a  of the read unit  30  is then guided in the first guideway  40  and the second guide pin  31   b  is guided in the second guideway  41 . The first slider  44 , the second slider  45  and the third slider  46  then exert the driving force in the y direction on the first guide pin  31   a , the second guide pin  31   b  and the third guide pin  31   c  of the base plate  31 . 
     FIG. 7  is a side view of the changer apparatus in a first intermediate position. In this first intermediate position the first guide pin  31   a  and the second guide pin  31   b  of the base plate  31  are disposed at the rearward end of the horizontal guideway section  40   a  of the first guideway  40  and the horizontal guideway section  41   a  of the second guideway  41 , respectively, which extend in the y direction. Upon a further movement of the sliding plate  43  in the y direction the first guide pin  31   a , the second guide pin  31   b  and the third guide pin  31   c  are urged upward in the z direction in the V-shaped slots  44   a ,  45   a  and  46   a  of the first slider  44 , the second slider  45  and the third slider  46 , respectively, as a result of which a second intermediate position is reached. The first guide pin  31   a  and the second guide pin  31   b  then move upward in the vertical guideway sections  40   b  and  41   b.    
   The second intermediate position is shown in side view in  FIG. 8 .  FIG. 8  shows that the first guide pin  31   a  and the second guide pin  31   b  are situated at the respective upper ends of the vertical guideway sections  40   b  and  41   b . This results in the read unit  30  being lifted, thereby causing the clamping disc  37  to be pressed onto the driving disc  38 , in a manner not shown, and the information disc  1  being clamped between the clamping disc  37  and the driving disc  38 . 
   The first intermediate position of  FIG. 7  is shown in plan view in  FIG. 9 . From  FIG. 9  it is apparent that in the first intermediate position the information disc  1  is held by the first guide  20 , the second guide  21  with the first transport wheel  25 , the third guide  22  with the transport wheel  26  as well as the fourth guide  23 . The first guide  20 , the second guide  21 , the third guide  22  and the fourth guide  23  are urged against the disc edge  1   a  of the information disc  1  under the spring loads of their pivotal arms and hold the information disc  1  in the first intermediate position. 
     FIG. 10  is a plan view which shows the changer apparatus with the information disc  1  in a play position. In this play position the first guide  20 , the second guide  21  with the first transport wheel  26 , the third guide  22  with the second transport wheel  26 , and the fourth guide  23  are pivoted away from the information disc  1 , as a result of which the V-shaped grooves of these guides no longer act upon the disc edge of the information disc  1 . The pivoting away of the first guide  20 , the second guide  21 , the third guide  22  and the fourth guide  23  is controlled by the movement of the sliding plate  43 , which performs a movement in the y direction between the second intermediate position and the play position. During this movement between the second intermediate position and the play position the sliding plate  43  urges the first guide  20 , the second guide  21 , the third guide  22  and the fourth guide  23  away from the information disc  1  against the pre-loading forces. 
   In the play position shown in  FIG. 10  the information disc  1  is held exclusively by the clamping disc  37  and the driving disc  38 . In the play position the information disc  1  is rotated as a result of the rotation of the driving disc  38 , and the information stored on the information disc  1  can be read by means of the read unit  30 . In the play position the laser mounting plate  35  is only coupled to the base plate  31  and, consequently, to the chassis plate  3  via the dampers  32 ,  33  and  34 . Thus, the laser mounting plate  35  is isolated from external vibrations and shocks of the housing  2  and the chassis plate  3  by means of the dampers  32 ,  33  and  34 , as a result of which the read unit  30  can read or play back the information stored on the information disc  1  without being affected by external vibrations. 
     FIG. 11  is a side view which shows the changer apparatus in the play position. In comparison with the second intermediate position shown in  FIG. 8  the sliding plate  43  has been moved in the y direction, so that the first guide pin  31   a , the second guide pin  31   b  and the third guide pin  31   c  have been urged downward in the V-shaped sliding slots  44   a ,  45   a  and  46   a . As a result of this, the read unit  30  has also been lowered with respect to the second intermediate position. 
   From the first intermediate position shown in  FIGS. 7 and 9  the information disc  1  it is possible to move the information disc  1  into the play position shown in  FIGS. 10 and 11  and also to move the information disc  1  into the stacking unit  4 . 
   For the transport into the stacking unit  34  from the first intermediate position shown in  FIG. 9  the information disc  1  is rolled onto the curve-shaped loading path  28  into the stacking unit  4 . Essentially, driving is effected by the second transport wheel  26 , which takes over the driving function from the first transport wheel  25 . The supporting function is essentially provided by the fourth guide  23 . 
     FIGS. 12 and 13  show the changer apparatus with the information disc  1  in the loading position shown in  FIG. 2 ,  FIG. 12  being a plan view and  FIG. 13  being a perspective view. The second transport wheel  26  has been pivoted out of the stacking unit  4 , so that now the information disc  1  together with the first holder compartment  8 , in accordance with  FIG. 2 , can be moved from this loading position  16  shown in  FIGS. 12  and  13  into one of the four upper stacking positions  13   a ,  13   b ,  13   c  or  13   d  by rotation of the threaded spindles  5 ,  6  and  7 . Conversely, the information disc  1  can be moved from the loading position shown in  FIG. 13  into the first intermediate position in that the second transport wheel  26  is pivoted against the disc edge  1   a  and the second transport wheel  26  is rotated in the opposite direction and subsequently into the eject position in that the first transport wheel  25  is driven. 
   In the situation shown in  FIGS. 12 and 13  the read unit  30  has been moved completely out of the range of operation of the stacking unit  4 .