Abstract:
A recording/reproducing apparatus includes a record medium cartridge holder having a main support portion with a cartridge carrying portion slidably arranged on it for withdrawing a cartridge held at a standby position to a withdrawal position. An insertion restricting portion prohibits passage of a cartridge in an improper orientation. A lock portion, arranged directly above the insertion restricting portion, locks the carrying portion in the standby position and releases the locking of the carrying portion when the cartridge passes through the insertion restricting portion.

Description:
This is a division of prior application Ser. No. 09/851,821 filed May 9, 2001 now U.S. Pat. No. 6,657,925. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a new recording and/or reproducing apparatus and a new recording medium cartridge holder. In particular, the present invention relates to a technique for realizing space saving of a recording and/or reproducing apparatus, and to a technique for preventing improper insertion of a recording medium cartridge, that is, insertion of a recording medium cartridge in an orientation other than a normal orientation in a recording medium cartridge holder with a simple mechanism. 
   In recording and/or reproducing apparatuses for recording and/or reproducing signals on and/or from a recording medium disk, it is required to provide a loading mechanism, that is, a mechanism for withdrawing the recording medium disk to a specific position in an apparatus main body and mounting the recording medium disk to a specific mounting position, and also to provide a mode formation mechanism, that is, a mechanism for bringing each of members into a specific state suitable for a reproducing or recording mode. 
   In related art recording and/or reproducing apparatuses, the above-described loading mechanism and mode formation mechanism have been provided at separate locations, particularly, as viewed from above, as individual mechanisms. Accordingly, there has arisen a problem that since these mechanisms are disposed at respective spaces, it is required to ensure a large space for these mechanisms in the apparatus. 
   On the other hand, there has been known a recording medium cartridge configured such that a recording medium is contained in a flat cartridge case formed into a rectangular shape having a long-side and short-side as viewed from above, wherein the recording medium cartridge is inserted with its long-side portion directed forwardly in the insertion direction. 
   In a recording and/or reproducing apparatus using the above-described recording medium cartridge, it is required to prevent the insertion of the recording medium cartridge in an orientation other than a normal orientation, that is, improper insertion of the recording medium cartridge in a recording medium cartridge holding portion for holding the recording medium cartridge. 
   Various mechanisms have been proposed for preventing insertion of a recording medium cartridge in a cartridge holder of a recording and/or reproducing apparatus with the front and rear sides or the upper and lower sides erroneously reversed to each other; however, effective means for preventing insertion of a recording medium cartridge in a cartridge holder with a short-side portion thereof directed forwardly in the insertion direction have been little proposed, and the proposed means have presented problems in terms of complicated mechanism and poor usability. 
   SUMMARY OF THE INVENTION 
   A first object of the present invention is to provide a recording and/or reproducing apparatus capable of realizing space saving. 
   A second object of the present invention is to provide a recording and/or reproducing apparatus capable of certainly preventing a recording medium cartridge, in which a recording medium is contained in a flat cartridge case formed into a rectangular shape having a long-side and short-side as viewed from above, the recording medium cartridge being inserted into a recording medium cartridge holding portion with its long-side portion directed forwardly in the insertion direction, from being inserted in the recording medium cartridge holding portion in an orientation other than a normal orientation, with a simple structure. 
   To achieve the above first object, according to a first aspect of the present invention, there is provided a recording and/or reproducing apparatus for recording and/or reproducing signals on and/or from a recording medium, including: recording and/or reproducing means for recording and/or reproducing signals on and/or from the recording medium; carrying means for carrying the recording medium; a first slider movable in one direction for moving the carrying means together with the recording medium up to a specific withdrawal position; and a second slider movable in a direction being substantially the same as the one direction for moving the recording medium carried by the carrying means to a recording and/or reproducing position corresponding to a position of the recording and/or reproducing means; wherein the first slider and the second slider are overlapped to each other in the vertical direction. 
   With this configuration, since the first slider mainly used for loading operation and the second slider mainly used for mode formation operation are overlapped to each other, it is possible to realize space saving, particularly, as seen from above. 
   The recording and/or reproducing means preferably includes a disk rotation drive mechanism for rotating a disk as the recording medium; and a signal recording and/or reproducing mechanism for recording and/or reproducing signals on and/or from the disk while being moved in the radial direction of the disk rotated by the disk rotation drive mechanism. 
   The first slider and the second slider are preferably driven by one motor. 
   With this configuration, it is possible to further enhance the space saving effect. 
   Preferably, the recording and/or reproducing means includes a magnetic head device for recording signals on the disk; and the second slider is further movable, after moving the disk to the recording and/or reproducing position, in the one direction for moving the magnetic head device to a position corresponding to a position of the disk mounted on the disk rotation drive mechanism. 
   With this configuration, it is possible to realize two different modes only by changing the movement amount of the second slider in the one direction, and hence to obtain a complicated function with a simple structure. 
   Preferably, the recording and/or reproducing apparatus further includes a disk holder having the carrying means; wherein the disk holder includes a main supporting member for movably supporting the carrying means, the main supporting member being movable in the direction perpendicular to a main body of the recording and/or reproducing apparatus; and the main supporting member is moved from the upper end to the lower end of a movement range thereof by movement of the second slider from the initial position to a specific position, to mount the disk supported by the carrying means on the disk rotation drive mechanism. 
   With this configuration, it is possible to make the movement space of the disk holder smaller than that of a related art disk holder turned to mount/dismount a recording medium disk on/from a disk rotation drive mechanism, and hence to reduce a space, particularly, in the height direction, of the recording and/or reproducing apparatus of the present invention. 
   Preferably, each of the first slider and the second slider has rack teeth meshed with a pinion gear rotated by the one motor; until the recording medium is withdrawn from the initial position to the specific withdrawal position, only the rack teeth of the first slider are meshed with the pinion gear and only the first slider is moved by rotation of the pinion gear; at the final stage of the movement of the first slider, the second slider is pushed by the first slider to be moved in the one direction, whereby the rack teeth of the second slider are meshed with the pinion gear and the rack teeth of the first slider are removed from the pinion gear; and only the second slider is moved in the one direction by further rotation of the pinion gear. 
   With this configuration, it is possible to move the two sliders in sequence at any time with a simple mechanism, and hence to enhance the space saving effect. 
   To achieve the above second object, according to a second aspect of the present invention, there is provided a recording and/or reproducing apparatus including: a recording medium cartridge holding portion in which a recording medium cartridge, configured such that a recording medium is contained in a flat cartridge case formed into a rectangular shape having a long-side and short-side, is inserted with its long-side portion directed forwardly in the insertion direction. The recording medium cartridge holding portion includes a main support portion; a carrying portion, supported on the main support portion in such a manner as to be movable from a standby position to a specific withdrawal position, for withdrawing the recording medium cartridge held at the standby position to the specific withdrawal position; a lock portion for locking the carrying portion at the standby position; and an insertion restricting portion for prohibiting the passing of the recording medium cartridge inserted in an orientation other than a normal orientation; wherein the lock portion releases the locking of the carrying portion by the recording medium cartridge passing through the insertion restricting portion. 
   With this configuration, since the lock of the carrying portion cannot be released unless the recording medium cartridge passes through the insertion restricting portion. Accordingly, in the case of insertion of the recording medium cartridge with its long-side portion directed forwardly in the insertion direction, since the recording medium cartridge cannot pass through the insertion restricting portion unless the cartridge is in a normal orientation, the improper insertion of the recording medium cartridge can be certainly prevented. In the case of insertion of the recording medium cartridge with its short-side portion directed forwardly in the insertion direction, even if the cartridge is inserted to a position deeper than a position at which the insertion restricting portion is formed while bypassing the insertion restricting portion, since the cartridge does not pass through the insertion restricting portion, the locking of the carrying portion cannot be released, with a result that the insertion of the cartridge can be certainly prevented. Further, such a structure can be simply realized only by disposing the lock portion at the position at which the locking by the lock portion is released by the recording medium cartridge passing through the insertion restricting portion. 
   Preferably, the carrying portion includes a turning lever turned between a first position and a second position; and the turning lever is turned from the first position to the second position by the recording medium cartridge passing through the insertion restricting portion, to release the locking of the carrying portion to the main support portion. 
   With this configuration, it is possible to carry the recording medium cartridge to the specific withdrawal position while certainly holding it by the carrying portion. 
   Preferably, the turning lever includes a first arm portion to be engaged to a bent portion of a guide groove formed in the main support portion; a second arm portion to be engaged in a hole portion formed in the main support portion; and a third arm portion provided at a position at which the third arm portion crosses the first arm portion and the second arm portion at approximately right angles; wherein when the third arm portion is turned by the contact thereof with the recording medium cartridge passing through the insertion restricting portion, the engagement of the first arm portion in the bent portion is released and the first arm portion is engaged in a sliding groove provided in such a manner as to be continuous to the bent portion and to be substantially in parallel to the movement direction of the carrying portion, and also the engagement of the second arm portion in the hole portion is released and the second arm portion is engaged with the recording medium cartridge, whereby the locking of the carrying portion at the standby position is released; and the carrying portion is allowed to carry the recording medium cartridge from the standby position to the withdrawal position. 
   With this configuration, since the carrying portion is not pushed by the recording medium cartridge until the carrying portion holds the recording medium cartridge, it is possible to certainly hold the recording medium cartridge on the carrying portion. 

   
     BREIF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view, seen obliquely forwardly from above, of a magneto-optical disk cartridge representative of a recording medium cartridge used for a recording and/or reproducing apparatus of the present invention; 
       FIG. 2  is a perspective view, seen from below, of the recording and/or reproducing apparatus, showing a state in which a shutter is located at an open position; 
       FIG. 3  is a plan view showing the entire configuration of the recording and/or reproducing apparatus; 
       FIG. 4  is a left side view showing the entire configuration of the recording and/or reproducing apparatus; 
       FIG. 5  is a right side view showing the entire configuration of the recording and/or reproducing apparatus; 
       FIG. 6  is a plan view of a cartridge holder of the recording and/or reproducing apparatus; 
       FIG. 7  is a bottom view of the cartridge holder; 
       FIG. 8  is a rear view of the cartridge holder; 
       FIG. 9  is an enlarged sectional view taken on line IX—IX of  FIG. 6 ; 
       FIG. 10  is a plan view of a main support of the recording and/or reproducing apparatus; 
       FIG. 11  is a bottom view of the main support; 
       FIG. 12  is a plan view of a connecting member of the recording and/or reproducing apparatus; 
       FIG. 13  is a bottom view of the connecting member; 
       FIG. 14  is a plan view of a carrying slider of the recording and/or reproducing apparatus; 
       FIG. 15  is a bottom of the carrying slider; 
       FIG. 16  is a plan view of the cartridge holder showing a state in which the disk cartridge is inserted in a normal orientation and the locking by a lock member is released; 
       FIG. 17  is an enlarged sectional view taken on line XVII—XVII of  FIG. 16 ; 
       FIG. 18  is a plan view, with parts partially cutaway, of the cartridge holder showing a state in which the disk cartridge is inserted in the normal orientation and the locking by a lock lever is released; 
       FIG. 19  is a plan view of the cartridge holder showing a state in which the disk cartridge is inserted in the normal orientation and is perfectly withdrawn in the cartridge holder; 
       FIG. 20  is a bottom view of the cartridge holder showing a state in which the disk cartridge is inserted in the cartridge holder with the rear side of the disk cartridge is erroneously directed forwardly; 
       FIG. 21  is an enlarged sectional view taken on line XXI—XXI of  FIG. 20 ; 
       FIG. 22  is a bottom view of the cartridge holder showing a state in which the disk cartridge is inserted in the cartridge holder with the back side of the disk cartridge erroneously directed upwardly; 
       FIG. 23  is an enlarged sectional view taken on line XXIII—XXIII of  FIG. 22 ; 
       FIG. 24  is a bottom view of the cartridge holder showing a state in which the disk cartridge is inserted in the cartridge holder with the side surface of the disk cartridge erroneously directed forwardly; 
       FIG. 25  is a plan view of a main body of the recording and/or reproducing apparatus; 
       FIG. 26  is a left side view of the main body of the recording and/or reproducing apparatus; 
       FIG. 27  is a right side view of the main body of the recording and/or reproducing apparatus; 
       FIG. 28  is a bottom view of the main body of the recording and/or reproducing apparatus; 
       FIG. 29  is a sectional view taken on line XXIX—XXIX of  FIG. 25 ; 
       FIG. 30  is a plan view showing a mode slider; 
       FIG. 31  is a right side view of the mode slider; 
       FIG. 32  is a plan view of a loading slider; 
       FIG. 33  is a plan view showing a rack formation portion of the loading slider; 
       FIG. 34  is a bottom view showing the rack formation portion of the loading slider; 
       FIG. 35  is a left side view showing the rack formation portion of the loading slider; 
       FIG. 36  is a plan view showing a limiter portion of the loading slider; 
       FIG. 37  is a right side view showing the limiter portion of the loading slider; 
       FIG. 38  is a left side view showing an overwriting head mechanism located at a standby position; 
       FIG. 39  is a left side view showing an overwriting head mechanism located at a recording position; 
       FIG. 40  is a plan view showing an essential portion of a mode formation mechanism located at an initial position; 
       FIG. 41  is a left side view showing an essential portion of the mode formation mechanism located at the initial position; 
       FIG. 42  is a left side view showing another essential portion of the mode formation mechanism located at the initial position; 
       FIG. 43  is a plan view of two sliders located at the initial positions; 
       FIG. 44  is a plan view of the two sliders in the course of movement from the initial positions to loading ended positions; 
       FIG. 45  is a plan view of the two sliders in a state being closer to the loading ended positions than those in the state shown in  FIG. 44  in the course of movement from the initial positions to the loading ended positions; 
       FIG. 46  is a plan view showing an essential portion of the mode formation portion at the loading ended position; 
       FIG. 47  is a left side view showing an essential portion of the mode formation portion at the loading ended position; 
       FIG. 48  is a left side view showing another essential portion of the mode formation portion at the loading ended position; 
       FIG. 49  is a plan view of the two sliders located at the loading ended positions; 
       FIG. 50  is a plan view of the two sliders in the course of movement from the loading ended positions to recording positions; 
       FIG. 51  is a plan view of the two sliders in a state being closer to the recording positions than those in the state shown in  FIG. 50  in the course of movement from the loading ended positions to the recording positions; 
       FIG. 52  is a plan view showing an essential portion of the mode formation mechanism located at the recording positions; 
       FIG. 53  is a left side view showing an essential portion of the mode formation mechanism located at the recording positions; 
       FIG. 54  is a left side view showing another essential portion of the mode formation mechanism located at the recording position; and 
       FIG. 55  is a plan view of the two sliders located at the recording positions. 
   

   DESCRIPTION OF THE INVENTION 
   Hereinafter, embodiments of a recording medium cartridge holder and a recording and/or reproducing apparatus according to the present invention will be described with reference to the accompanying drawings. 
   In the embodiments shown in the figures, the present invention is applied to a mechanism of preventing improper insertion of a recording medium cartridge including a flat cartridge case and a disk-like recording medium rotatably disposed therein, and to a recording and/or reproducing apparatus using a magneto-optical disk cartridge containing a magneto-optical disk as the above recording medium. 
   First, a recording medium cartridge, that is, a magneto-optical disk cartridge (hereinafter, referred to as “disk cartridge”) used in the embodiments will be described with reference to  FIGS. 1 and 2 . 
   A disk cartridge  1  includes a flat cartridge case  2  having a rectangular shape close to a square shape. The length of the cartridge case  2  in the longitudinal direction AB is slightly shorter than the length thereof in the lateral direction CD. An insertion port  3  is formed in a central portion of the back surface of the cartridge case  2 . An access hole  4  for allowing access of laser light emitted from an optical pickup is formed in a portion, offset from the insertion port  3  in the direction D, of the back surface of the cartridge case  2 . A head insertion port  5 , in which a magnetic head for recording is to be inserted, is formed in the top surface at a position corresponding to the access hole  4 . 
   A shutter  6  is provided in such a manner as to be movable from a close position shown in FIG.  1  and an open position shown in FIG.  2 . The shutter  6  integrally has an upper covering portion  6   a  for covering the head insertion port  5 , a lower covering portion  6   b  for covering the access hole  4 , and an intermediate portion  6  for connecting these covering portions  6   a  and  6   b  to each other at a side edge portion of the disk cartridge. An engagement hole  6   d  is formed in the intermediate portion  6   c . The shutter  6  is locked at the close position by locking means (not shown) in a state that the covering portions  6   a  and  6   b  cover the head insertion port  5  and the access hole  4 , respectively. 
   A groove  7  is formed in a side edge surface in the direction D of the cartridge case  2 . The groove  7  extends from the front end, that is, the end in the direction A of the cartridge case  2  to a portion slightly short of the rear end, that is, the end in the direction B of the cartridge case  2 . 
   A groove  8  is formed in a side edge surface in the direction C of the cartridge case  2 . The groove  8  extends from the front end of the cartridge case  2  to a portion slightly offset forwardly from an intermediate portion of the cartridge case  2 . Each of the grooves  7  and  8  is slightly offset upwardly from the center in the vertical direction. Accordingly, at the left side portion of the front end of the cartridge  2 , the thickness of a portion  7   a  over the groove  7  is thinner than that of a portion  7   b  under the groove  7 , and in the right side portion of the front end of the cartridge  2 , the thickness of a portion  8   a  over the groove  8  is thinner than that of a portion  8   b  under the groove  8  (see FIG.  1 ). 
   An approximately semi-circular cutout  9  opened downwardly, sideways is formed in each of both side edge portions of the back surface of the cartridge case  2  at a position near the front end. 
   A magneto-optical disk  10  is rotatably contained in the cartridge case  2 . A disk-like core  11 , formed of a magnetic body, mounted at a central portion of the magneto-optical disk  10  faces downwardly through the insertion port  3  formed at the central portion of the back surface of the cartridge case  2 . A central hole  11   a  is formed at the central portion of the core  11 . A circular fitting recess  11   b  is formed in the back surface of the core  11 . 
   A recording and/or reproducing apparatus of the present invention will be described below with reference to a plan view in  FIG. 3 , a left side view in  FIG. 4 , and a right side view in  FIG. 5 ; a cartridge holder of the present invention will be described with reference to a plan view in  FIG. 6 , a bottom view in  FIG. 7 , a rear view in  FIG. 8 , and a sectional view in  FIG. 9 ; and a main support of the cartridge holder will be described with reference to a plan view in  FIG. 10 and a  bottom view in FIG.  11 . In addition, the left, right, front, and rear sides in the following description are based on those in the plan views. 
   A recording and/or reproducing apparatus  100  for recording and/or reproducing signals on/from a magneto-optical disk  9 , for example, Mini Disk (trade name) by using the disk cartridge  1  includes a base chassis  110  on which components necessary for recording and/or reproducing are mounted or supported. 
   A cartridge holder  120  is supported on the upper surface side of the base chassis  110  in such a manner as to be movable in the vertical direction. The cartridge holder  120  mainly includes a main support  130  having a rectangular shape slightly longer in the longitudinal direction, that is, in the direction EF, a connecting member  140  mounted on the main support  130 , and a carrying slider  150 . 
   The main support  130  is made from a synthetic resin, and as is apparent from  FIGS. 10 and 11 , a large opening portion  131  is formed in a rear end portion, that is, a portion excluding a portion on the direction F side, of an approximately right half of the main support  130 . A projecting rib  131   a  is formed on the right side edge, that is, on the side edge on the direction H side of the opening portion  131 , except for the front end portion, that is, the end portion in the direction E side. To be more specific, the projecting rib  131   a  projects from an approximately vertical intermediate portion of the right side edge of the opening portion  131 . A sliding groove  132  is formed in the left side edge, that is, in the side edge on the direction G side of the main support  130  in such a manner as to extend from a portion offset slightly rearwardly from the center in the longitudinal direction to the front end portion. A lock portion  132   a  recessed slightly rightwardly is formed at the rear end portion of the sliding groove  132 . Guide slits  133  and  134  are formed in a portion, between the opening portion  131  and the sliding groove  132 , of the main support  130 . The guide slits  133  and  134  substantially extend from the front end portion to the rear end portion of the main support  130 . A projecting rib  133   a  is formed along the left side edge of the guide slit  133  on the left side, and projecting ribs  134   a  are formed along the left and right side edges of the guide slit  134  on the right side of the guide slit  133 . A rectangular arrangement hole  130   b  longer in the longitudinal direction is formed in a left rear end portion of the main support  130 . 
   A shutter opening/closing member  160  made from a spring material is fixed on the outer side surface of a right side wall  130   a  of the main support  130  of the cartridge holder  120  (see FIG.  5 ). The shutter opening/closing member  160 , which is longer in the longitudinal direction, that is, in the direction EF, has a shutter opening piece  161  projecting leftwardly from an approximately intermediate portion of the shutter opening/closing member  160  (see FIG.  7 ), and a shutter closing piece  162  projecting leftwardly from the rear end portion of the shutter opening/closing member  160  (see FIG.  11 ). The shutter opening piece  161  is formed into a flat plate having a rectangular shape longer substantially in the longitudinal direction, and has at a front end portion of the left side edge thereof, a tilt edge  161   a  tilted leftwardly, forwardly. The shutter closing piece  162  has, at a front end portion of the left side edge, a front tilt edge  162   a  and has, at a rear end portion of the left side edge, a rear tilt edge  162   b . The tilting angle of the front tilt edge  162   a  is larger than that of the rear tilt edge  162   b . Both the shutter opening piece  161  and the shutter closing piece  162  project in the right side wall  130   a  of the main support  130  of the cartridge holder  120  through through-holes formed in the right side wall  130   a . Two portions, positioned in front of and at the back of the shutter opening piece  161 , of the shutter opening/closing member  160  are screwed in the right side wall  130   a , whereby the shutter opening piece  161  is prevented from being moved rightwardly and leftwardly. On the other hand, the shutter closing piece  162  is usually kept as projecting in the right side wall  130   a , and when pushed from the left side, the shutter closing piece  162  is moved rightwardly because the rear end portion of the shutter opening/closing member  160  is elastically flexed. 
   As shown in  FIG. 10 , a connecting hole  135  is formed at a position near the rear end of a portion, along the left side edge of the opening portion  131 , of the main support  130 . A sliding pin  136  is provided on each of the left and right side surfaces of the main support  130  at a position slightly offset rearwardly, that is, in the direction F, from an intermediate portion of the side surface in the longitudinal direction in such a manner as to project outwardly therefrom. A connecting piece  136  is provided at an approximately lateral central position on a front end portion of the main support  130  in such a manner as to project forwardly therefrom. 
   Supporting surface portions  138  and  139  are respectively provided at lower edges of rear end portions of the left and right side surfaces of the main support  130  of the cartridge holder  120  in such a manner as to project in the direction where they come close to each other. 
   The connecting member  140  will be described below with reference to a plan view in  FIG. 12 and a  bottom view in FIG.  13 . 
   The connecting member  140  is formed by bending a plate material. As shown in  FIGS. 12 and 13 , the connecting member  140  integrally has a main portion  141  formed into a plate shape longer in the lateral direction, and two pieces  142  and  143  to be supported which project nearly downwardly from the left and right side edges of the main portion  141  respectively. Projecting pieces  142   a  and  143   a  are respectively provided on the rear edges of the lower end portions of the pieces  142  and  143  to be supported in such a manner as to project in the direction where they come close to each other. Pins  142   b  and  143   b  to be supported project from the right surface of a lower end portion of the left piece  142  to be supported and from the right surface of a lower end portion of the right piece  143  to be supported, respectively. A side surface portion  144  projects downwardly from a front end portion of the left side edge of the main portion  141 . A restricting piece  144   a  projects rightwardly from the lower edge of the side surface portion  144 , and a spring catch piece  144   b  projects leftwardly from the upper end of the side surface portion  144 . 
   Left and right engagement pieces  145  and  146  project forwardly from an approximately lateral central portion of the front edge of the main portion  141  of the connecting member  140 . The right engagement piece  146  once projects downwardly and then projects forwardly, and accordingly, it is formed into an approximately L-shape as viewed from right. These engagement pieces  145  and  146  look to be opposed to each other in the vertical direction with a gap put therebetween as viewed from right or left. 
   An arrangement opening  147  is formed in a left end portion of the main support  141  of the connecting member  140 , and a lock member  170  is disposed in the arrangement opening  147 . As shown in  FIG. 9 , the lock member  170  made from a synthetic resin integrally has a base portion  171  formed into a recess opened rearwardly, and a claw piece  172  projecting forwardly from a front end portion of the base portion  171 . A lock claw  173  projects downwardly from the front end of the claw piece  172 . A lower end surface  173   a  of the lock claw  173  is tilted slightly rearwardly, upwardly. A pin  171   a  to be supported projects from each of both side surfaces of a portion, near the rear end, of the base portion  171 . Both the pins  171   a  to be supported are turnably engaged with supporting pieces  148  projecting downwardly from both sides of a rear end portion of the arrangement opening  147  of the main support  141  of the connecting member  140 , whereby the lock member  170  is supported by the connecting member  140  in such a manner as to be turnable in the direction where the front end of the lock member  170  is moved substantially in the vertical direction. The downward turning of the lock member  170  is restricted by the contact of the rear end of the base portion  171  with the back surface of the main portion  141  of the connecting member  140 , while the upward turning of the lock member  170  is restricted by the contact of a restricting pin  171   b  projecting rightwardly from a front end portion of the base portion  171  with the back surface of the base portion  141  of the connecting member  140 . 
   A spring catch piece  147   a  is provided at a portion, offset slightly forwardly from a central portion, of the right side edge of the arrangement opening  147  of the connecting member  140 . A coil portion  174   a  of a torsion-coil spring  174  is wound around the spring catch piece  147   a . A forwardly extending arm  174   b  of the coil spring  174  is brought into elastic-contact with the upper surface of the main portion  141  of the connecting member  140 , and a rearwardly extending arm  174   c  of the coil spring  174  is brought into elastic-contact with the upper surface of a front end portion of the base portion  171  of the lock member  170 . The lock member  170  is thus biased downwardly. 
   The connecting member  140  is connected to the main support  130  as follows: namely, the restricting piece  144   a  formed on the left side portion of the connecting member  140  is positioned on the back side of the left side portion of the main support  130 ; the right engagement piece  146  of the connecting member  140  is engaged in the connecting hole  135  of the main support in the main support  130  with the engagement sliding piece  153   a  slidably engaged on the upper surface of the projecting rib  133   a  formed on the left side surface of the sliding slit  133 . The projecting rib  154  is slidably engaged in the guide slit  134  formed in the main support  130  with the engagement sliding pieces  154   a  slidably engaged on the upper surfaces of the projecting ribs  134   a  formed on the left and right side surfaces of the guide slit  134 . An engagement sliding piece  151   a  projects rightwardly from the upper surface of a right end portion of the upper surface portion  151 . The engagement sliding piece  151   a  is slidably engaged on the upper surface of the projecting rib  131   a  formed on the right side surface of the opening portion  131  of the main support  130 . The carrying slider  150  is thus supported on the back surface of the main support  130  in such a manner as to be movable in the longitudinal direction, that is, the direction EF. 
   A rearwardly extending supporting piece  155  is formed on a portion, offset rightwardly from an intermediate portion, of the lower edge of the front surface portion  152  of the carrying slider  150 . A projecting piece  156 , which projects rearwardly, is formed on a left end portion of the upper surface portion  151 . A hole  156   a  to be locked is formed in a central portion of the projecting piece  156 , and a rear edge  156   a ′ of the hole  156   a  to be locked is tilted forwardly, upwardly. A supporting piece  156   b  projects downwardly from the left side edge of the projecting piece  156 , and an insertion restricting piece  156   c  projects rightwardly from the lower end of the supporting piece  156   b  (see FIG.  9 ). The insertion restricting piece  156   c  is formed into a small plate shape extending in the horizontal direction, and is opposed to the lock hole  156   a . To be more specific, the insertion restricting piece  156   c  is located at a height corresponding to the height of the left groove  8  of the disk cartridge  1  inserted in the cartridge holder  120  in a normal orientation. 
   A left end portion of the front surface portion  152  of the carrying slider  150  is cutout, to form a cutout portion  152   a . A connecting piece  157  projects forwardly from a lower end portion, close to the cutout portion  152   a , of the front surface portion  152 , and an engagement projection  157   a  projects leftwardly from a front end portion of the connecting piece  157 . 
   A lock lever  180  is turnably supported on the back surface of a left end portion of the upper surface portion  151  of the carrying slider  150 . The lock lever  180  has three arm pieces  181 ,  182 , and  183  extending in the directions perpendicular to each other. A hole  184  to be supported, extending in the vertical direction, is formed in an intermediate portion at which bases of the three arm pieces  181 ,  182  and  183  are connected to each other. The first arm piece  181  extending substantially forwardly from the intermediate portion has a lock pin  181   a  projecting upwardly from a tip portion of the first arm piece  181 . The second arm piece  182  extending substantially rightwardly from the intermediate portion is taken as a piece to be operated. The third arm piece  183  extending substantially rearwardly from the intermediate portion has, at its tip portion, a lock projection  183   a  projecting leftwardly from the upper end of the tip portion and an engagement projection  183   b  projecting rightwardly from the lower end of the tip portion. A supporting shaft  158  projecting downwardly from the front end of a left end portion of the upper surface portion  151  of the carrying slider  150  is inserted in the hole  184  to be supported, whereby the lock lever  180  is turnably supported by the carrying slider  150 . The lock lever  180  is biased clockwise, that is, in the direction CW as viewed from above by a spring (not shown). 
   A click member  190  made from a plate spring material is fixed to a right end portion of the front surface portion  152  of the carrying slider  150 . The click member  190  has a piece  191  to be supported by the front surface portion  152 , and a lower surface portion  192  projecting rearwardly from the lower edge of the piece  191  to be supported. A rear end portion of the lower surface portion  192  projects rightwardly. Accordingly, the lower surface portion  192  has an approximately L-shape. An engagement projection  193 , swelled to project upwardly, is formed on a rightwardly projecting portion of the lower surface portion  192 . To be more specific, the engagement projection  193  is obtained by forming left and right slits extending in the longitudinal direction in a rear surface portion  192 , thereby upwardly swelling a portion between the two slits. 
   In a state in which the carrying slider  150  is located at the rear end of the movement range, that is, the standby position, the lock claw  173  of the lock member  170  supported by the connecting member  140  is engaged in the hole  156   a  to be locked of the carrying slider  150 ; the lock projection  183   a  of the lock lever  180  is engaged in an engagement hole  130   d  formed in a rear end portion of the left side wall  130   c  of the main support  130  of the cartridge holder  120  (see FIG.  18 ); and the lock pin  181   a  of the lock lever  180  is engaged in the lock portion  132   a  formed at the rear end of the sliding groove  132  of the main support  130  of the cartridge holder  120 . That is to say, with the above-described engagement of the lock members, the carrying slider  150  is locked at the rear end of the movement range, that is, at the standby position. 
   A procedure of inserting the disk cartridge  1  in the cartridge holder  120  will be described below. 
   The insertion of the disk cartridge  1  in the cartridge holder  120  in a normal orientation will be first described. In the normal orientation, the upper surface of the cartridge case  2  is directed upwardly, and the front end, that is, the end in the direction A, of the cartridge case  2  is directed forwardly, that is, in the direction E, of the apparatus. 
   As the disk cartridge  1  is inserted in the cartridge holder  120  in the normal orientation while being slid on the supporting surface portions  138  and  139 , the insertion restricting piece  156   c  of the carrying slider  150  is relatively inserted in the left groove  8  in the disk cartridge  1 , whereby the disk cartridge  1  is inserted toward the carrying slider  150 . When the disk cartridge  1  is further inserted in the cartridge holder  120 , the lower end surface (tilt surface)  173   a  of the lock claw  173  of the lock member  170  is pushed by a front end portion of the disk cartridge  1 . As a result, the lock member  170  is turned upwardly against the biasing force of the torsion-coil spring  174 , so that the tilt surface  173   a  of the lock claw  173  comes to be opposed to the tilt surface  156   a ′ at the rear end of the hole  156   a  to be locked of the carrying slider  150  (see FIGS.  16  and  17 ). Accordingly, as the carrying slider  150  is moved forwardly from this state, the tilt surface  173   a  of the lock claw  173  is relatively slid upwardly on the tilt surface  156   a ′ of the hole  156   a  to be locked. That is to say, the locking of the carrying slider  150  by the lock claw  173  is released in the step shown in  FIGS. 16 and 17 . When the disk cartridge  1  is still further inserted in the cartridge holder  120 , the tip of the second arm piece  182  of the lock lever  180  is pushed by the front end surface of the disk cartridge  1 . As a result, the lock lever  180  is turned counterclockwise, that is, in the direction CCW, as seen from above, against the biasing force of the spring (not shown), so that the lock pin  181   a  provided on the first arm piece  181  is removed leftwardly from the lock portion  132   a  formed at the rear end of the sliding groove  132  of the main support  130 , and the lock projection  183   a  provided at the tip of the third arm piece  183  is removed rightwardly from the engagement hole  130   d  formed in the left side surface portion  130   c  of the main support  130 . In this way, the locking of the carrying slider  150  at the standby position is entirely removed (see FIG.  18 ). Further, the engagement projection  183   b  formed at the tip portion of the third arm piece  183  is engaged in the cutout  9  formed in the lower portion of the left side edge of the disk cartridge  1 , and simultaneously the lower surface portion  192  of the clock member  190  flexed downwardly by the front end portion of the disk cartridge  1  is returned upwardly and the engagement projection  193  is engaged in the cutout  9  formed in the lower portion of the right side edge of the disk cartridge  1 . In this way, the disk cartridge  1  is held by the carrying slider  150 . 
   When the disk cartridge  1 , which has been held by the carrying slider  150 , is further inserted in the cartridge holder  120 , the carrying slider  150  is moved forwardly together with the disk cartridge  1 . When the carrying slider  150  is slightly moved forwardly, the movement thereof is detected by a sensor (not shown), and a mode formation mechanism (which will be described later) is driven on the basis of the detection result of the sensor, to move the carrying slider  150  up to a specific forward withdrawal position. As a result, the disk cartridge  1  is carried to a specific withdrawal position by the carrying slider  150  (see FIG.  19 ). This will be described in detail later. 
   The insertion of the disk cartridge  1  in the cartridge holder  120  in an erroneous orientation will be described below. The insertion of the disk cartridge  1  in an erroneous orientation includes the insertion of the disk cartridge in a state in which the rear side of the cartridge in the normal orientation is directed forwardly, the insertion of the disk cartridge in a state in which the upper side of the cartridge in the normal orientation is directed downwardly, and the insertion of the disk cartridge in a state in which the shorter side of the cartridge is directed forwardly. 
   When the disk cartridge  1  is inserted in the state in which the rear side of the disk cartridge  1  in the normal orientation is directed forwardly, since each of the grooves  7  and  8  does not reach the rear end of the disk cartridge  1 , the rear end surface of the disk cartridge  1  is brought into contact with the insertion restricting piece  156   c  of the cartridge holder  120 , with a result that the disk cartridge  1  can no longer enter in the cartridge holder  120  (see FIGS.  20  and  21 ). 
   When the disk cartridge  1  is inserted in the state in which the upper side of the disk cartridge  1  in the normal orientation is directed downwardly, since the vertical position of the groove  7 , provided at the end portion in the direction D, of the disk cartridge  1  is different from the height position of the insertion restricting piece  156   c  of the cartridge holder  120 , the insertion restricting piece  156   c  is brought into contact with the portion  7   b , higher than the groove  7 , of the end portion in the direction D of the front end surface of the disk cartridge  1 , more specifically, with a taper portion  7   b ′ continuous to the portion  7   b  higher than the groove  7 , with a result that the disk cartridge  1  can no longer enter in the cartridge holder  120  (see FIGS.  22  and  23 ). 
   When the disk cartridge  1  is inserted in the state in which the shorter side of the disk cartridge  1  is directed forwardly and further it is inserted without interfering with the insertion restricting piece  156   c , since the disk cartridge  1  enters deeper than the position at which the insertion restricting piece  156   c  is provided, the second arm piece  182  of the lock lever  180  is pushed rearwardly by the front end surface of the disk cartridge  1 , whereby the lock lever  180  is turned counterclockwise, that is, in the direction CCW as viewed from above, so that the lock pin  181   a  provided on the first arm piece  181  is removed leftwardly from the lock portion  132   a  of the sliding groove  132  (see FIG.  24 ). However, since the disk cartridge  1  does not pass through the portion at which the insertion restricting piece  156   c  is positioned, that is, the portion at which the lock claw  173  of the lock member  170  is positioned, the engagement between the lock claw  173  of the lock member  170  and the hole  156   a  to be locked of the carrying slider  150  is not released, with a result that the carrying slider  150  cannot be moved forwardly. 
   As described above, the disk cartridge  1  cannot be inserted in the cartridge holder  120  unless it is inserted in the normal orientation. Such limitation is realized by providing the insertion restricting piece  156   c  on the carrying slider  150 , and providing the lock means (lock member  170 ) for locking the carrying slider  150  at the standby position, at the position opposed to the insertion restricting piece  156   c  in the vertical direction, wherein the locking by the lock means is released by the disk cartridge  1  which has overcome the limitation by the insertion restricting piece  156   c  and passes through the insertion restricting piece  156   c . As a result, it is possible to certainly, simply prevent improper insertion of the disk cartridge  1 . 
   A main body of the recording and/or reproducing apparatus will be described below in detail with reference to  FIGS. 25  to  29 . 
   The above-described cartridge holder  120  is supported on the vase chassis  110  in such a manner as to be movable in the vertical direction. 
   The base chassis  110 , made from a synthetic resin, is provided with two supporting pieces  111 , two guide columns  112 , an engagement piece  113 , and a slip-off preventive piece  114 . The supporting pieces  111  projecting upwardly are provided on left and right ends of a rear end portion of the base chassis  110 . Supporting holes  111   a  are formed in the supporting pieces  111 . The guide columns  112  projecting upwardly are provided at positions, slightly offset rearwardly from intermediate portions in the longitudinal direction, of the left and right edges of the base chassis  110 . Guide grooves  112   a  extending in the vertical direction are formed in opposed surfaces of the guide columns  112 . The engagement piece  113  projecting upwardly is provided at a position, slightly offset from an intermediate portion in the lateral direction, of a front end portion of the base chassis  110 . An engagement sliding hole  113   a  longer in the vertical direction is formed in the engagement sliding piece  113  (see FIG.  4 ). The slip-off preventing piece  114  is erected on the left side of the left supporting piece  111  in such a manner as to be slightly spaced therefrom. 
   The cartridge holder  120  in a tilt posture with the front end portion positioned slightly upwardly is held above the base chassis  110 . Then, the pins  142   b  and  143   b  to be supported of the connecting member  140  are inserted, from the left side, in the supporting holes  111   a  of the supporting pieces  111  of the base chassis  110 , and the cartridge holder  120  is turned in the direction in which the front end portion thereof is moved downwardly. With this turning, the sliding pins  136  of the cartridge holder  120  are vertically slidably engaged in the guide grooves  112   a  formed in the guide columns  112  of the base chassis  110 , and a connecting piece  137  formed on the front end portion of the cartridge holder  120  is vertically slidably engaged in the engagement sliding hole  113   a  of the engagement piece  113  formed on the front end portion of the base chassis  110 . A tensile coil spring  116  (see  FIG. 4 ) is stretched between the spring catch piece  144   b  of the connecting member  140  of the cartridge holder  120  and a spring catch piece  115  projecting from the left side surface of a rear end portion of the base chassis  110 , whereby the connecting member  140  is biased in the direction in which the front end portion thereof is moved downwardly. 
   As described above, the cartridge holder  120  is supported on the base chassis  110  in such a manner as to be movable in the vertical direction. In the state in which the cartridge holder  120  is thus supported on the base chassis  110 , the left piece  142  to be supported of the connecting member  140  of the cartridge holder  120  is positioned between the left supporting piece  111  and the slip-off preventive piece  114  of the base chassis  110 , and accordingly, the leftward movement of the connecting member  140  is limited. As a result, it is possible to prevent the pins  142   b  and  143   b  to be supported from being slipped off leftwardly from the supporting holes  111   a  of the supporting pieces  111  of the base chassis  110 . 
   A mode formation mechanism, a disk rotation drive mechanism, an optical pickup mechanism, an overwriting head mechanism, and the like are mounted on the above-described base chassis  110 , to constitute a main body  200  of the recording and/or reproducing apparatus  100 . 
   The mode formation mechanism includes two sliders, that is, a mode slider  210  and a loading slider  220 . 
   The mode slider  210 , which is made from a synthetic resin, is supported on the upper surface of the base chassis  110  in such a manner as to be movable in the longitudinal direction, that is, in the direction EF (see FIG.  25 ). As shown in  FIGS. 30 and 31 , the mode slider  210  has a rack formation portion  211  formed into a plate shape longer substantially in the longitudinal direction, and a head drive portion  212  projecting rightwardly, that is, in the direction H from a front end portion of the rack formation portion  211 . Rack teeth  213  are formed on the right side edge of the rack formation portion  211  in a range from an intermediate portion in the longitudinal direction to a portion near the front end. An engagement cutout  214  extending rightwardly, forwardly is formed in a portion, slightly offset from an intermediate portion in the longitudinal direction, of the left side edge of the rack formation portion  211 . A low side wall  211   a  is erected on a portion, excluding the engagement cutout  214 , of the left side edge of the rack formation portion  211 . A piece  211   b  to be pushed, which projects leftwardly, is provided on each of the front and rear end portions of the rack formation  211  at a position outside the side wall  211   a . A guide groove  215  extending in the longitudinal direction is formed in the upper surface of the rack formation portion  211  in such a manner as to extend along the right side edge. A cam portion  216  is formed on a front end portion of the side wall  211   a  of the rack formation portion  211 . The upper edge of the cam portion  216  has a rear end portion  216   a  extending in the horizontal direction at the highest position and a tilt portion  216   b  tilted forwardly, downwardly from the rear end portion  216   a.    
   A cam portion  217  is formed on the head drive portion  212  of the mode slider  210  in such a manner as to extend in the longitudinal direction along the right side edge. The upper edge of the cam portion  217  has a high level portion  217   a  disposed at the rear end in such a manner as to extend in the horizontal direction at the highest position, a low level portion  217   b  disposed at the front end in such a manner as to extend in the horizontal direction at a low position, and a tilt portion  217   c  which connects the high level portion  217   a  to the low level portion  217   b  and which is tilted forwardly, downwardly. An auxiliary piece  217   d  is formed on the head drive portion  212  in such a manner as to be disposed over the portions  217   a ,  217   b  and  217   c  of the upper edge of the cam portion  217  with a slight gap put therebetween, whereby a cam groove following the shape of the upper edge of the cam portion  217  is formed. A slit  212   a  to be guided, which extends in the longitudinal direction, is formed in the head drive portion  212 . 
   A slit  117  extending in the longitudinal direction is formed in a portion along the left side edge of the base chassis  110  (see FIG.  28 ). A front end portion of a lock piece  230  is turnably supported by the right side edge near the front end of the slit  117 , and a lock pin  231  projects from a rear end portion of the lock piece  230  (see FIGS.  44  and  45 ). 
   The mode slider  210  is supported on the upper surface of the base chassis  110  in such a manner as to be slidable in the longitudinal direction. In addition, a guide projection  110   a  erected on the base chassis  110  is slidably engaged in the slit  212   a  to be guided of the mode slider  210 . An auxiliary member  240  is fixed on the left side edge of the base chassis  110 , and a step  241  is formed on the lower end of the right side surface of the auxiliary member  240 . The pieces  211   b  to be pushed of the mode slider  210  are slidably engaged between the step  241  and the upper surface of the base chassis  110  (see FIG.  29 ). In addition, the above-described left guide column  112  and the spring catch piece  115  are formed on the auxiliary member  240 . 
   The loading slider  220  has a rack formation portion  250  and a limiter portion  260 . 
   The rack formation portion  250  made from a synthetic resin having a good sliding characteristic is, as shown in  FIGS. 32  to  35 , formed into a plate shape longer substantially in the longitudinal direction. Rack teeth  251  are formed over the right side edge of the rack formation portion  250 . A slit  252  opened rearwardly is formed in a portion, near the left side edge, of the rack formation portion  250  in such a manner as to extend from the rear end to an approximately intermediate portion in the longitudinal direction. A spring catch piece  253  projects from the deepest end of the slit  252 . Two guide projections  254  are formed on a portion, near the right side edge, of the rack formation portion  250  in such a manner as to be spaced from each other in the longitudinal direction. A shallow groove  255  extending in the longitudinal direction is formed in a front end portion of the rack formation portion  250  at positions offset leftwardly from these guide projections  254 . A projecting rib  256  projecting downwardly is formed on the left side edge of the rack formation portion  250 . A cutout  256   a  is formed in the projecting rib  256  in such a manner as to extend from an intermediate position in the longitudinal direction to a position near the rear end. A tilt surface  256   b  tilted leftwardly, rearwardly is formed on a rear end portion of the projecting rib  256 . Three sliding projections  257  are provided on a portion, near the right side edge, of the back surface of the rack formation portion  250  in such a manner as to be spaced from each other in the longitudinal direction. 
   The limiter portion  260  made from a synthetic resin is, as shown in  FIGS. 36 and 37 , formed into a plate shape longer substantially in the longitudinal direction. The length of the limiter portion  260  is slightly shorter than that of the rack formation portion  250 . The width of the limiter portion  260  is narrower than that of the rack formation portion  250  by a projecting width of rack teeth  25 . A slit  261  opened rearwardly is formed in a portion, near the left side edge, of the limiter portion  260  in such a manner as to extend from an approximately intermediate portion in the longitudinal direction to the rear end. A spring catch piece  262  projects from a portion, which crosses the extension of the slit  261 , of a front end portion of the limiter portion  260 . Two slits  263  to be guided, which extend in the longitudinal direction, project from a portion, near the right side edge, of the limiter portion  260  in such a manner as to be spaced from each other in the longitudinal direction. A connecting column  264  is erected on a longitudinal intermediate portion along the right side edge of the limiter portion  261 . A connecting groove  264   a  opened upwardly is formed in a right side surface of the connecting column  264  in such a manner as to extend in the vertical direction. A projection piece  265  projects downwardly from an approximately intermediate position in the longitudinal direction of a left side edge portion of the limiter portion  260 . An elastic piece  266  extending in the longitudinal direction is formed between the deepest end of the slit  261  of the limiter portion  260  and the spring catch piece  262 . The elastic piece  266  is obtained by forming a U-shaped slit opened forwardly and extending longer in the longitudinal direction, thereby swelling a portion surrounded by the U-shaped slit. A projection  266   a  is formed on the back surface of a front end portion of the elastic piece  266  in such a manner as to slightly project downwardly from the back surface of the limiter portion  260 . 
   The limiter portion  260  is overlapped to the rack formation portion  250 . The guide projections  254  of the rack formation portion  250  are slidably engaged in the slits  263  to be guided of the limiter portion  260  in such a manner as to be prevented from being slipped-off from the slits  263  to be guided. The spring catch piece  253  of the rack formation portion  250  is slidably engaged in the slit  261  of the limiter portion  260 . The projection  266   a  formed on the back surface of the front end portion of the elastic piece  266  of the limiter portion  260  is slidably engaged in the shallow groove  255  formed in the upper surface of the rack formation portion  250 . The projection piece  265  of the limiter portion  260  is positioned in the cutout  256   a  formed in the left side edge of the rack formation portion  250  in such a manner as to be movable in the longitudinal direction. A limiter spring (tensile coil spring) is stretched between the spring catch piece  253  of the rack formation portion  250  and the spring catch piece  262  of the limiter portion  260 . The limiter portion  260  is thus connected to the rack formation portion  250 . As viewed from above, the rack teeth  251  of the rack formation portion  250  project leftwardly from the left side edge of the limiter portion  260 . 
   The limiter portion  260  is biased to the rack formation portion  250  by the limiter spring  267  and is kept as still by the contact of the spring catch piece  253  of the rack formation portion  250  with the deepest end of the slit  261  of the limiter portion  260 . When a force against the biasing force of the limiter spring  267  is applied to the limiter portion  260 , that is, a forward force is applied to the limiter portion  260 , the limiter portion  260  is moved forwardly, that is, in the direction E (see  FIG. 25 ) relative to the rack formation portion  250 . The movement of the limiter portion  260  is stopped when the projection  266   a  of the elastic piece  266  of the limiter portion  260  comes in contact with the front end of the shallow groove  255  of the rack formation portion  250 . The assembly of the rack formation portion  250  and the limiter portion  260  thus acts as the loading slider  220 . 
   The loading slider  220  configured as described above is overlapped on the mode slider  210  in such a manner as to be movable in the longitudinal direction. To be more specific, the sliding projections  257  formed on the back surface of the rack formation portion  250  of the loading slider  220  are slidably engaged in the guide groove  215  formed in the upper surface of the mode slider  210 . A hood piece  243 , which projects leftwardly from the upper edge of a side wall  242  projecting upwardly from the left side edge of the auxiliary member  240 , covers from above the upper surface of a left side edge portion of the limiter portion  260  of the loading slider  220  (see FIG.  29 ), thereby preventing the loading slider  220  from being slipped-off from the mode slider  210 . 
   In the state in which the mode slider  210  and the loading slider  220  are overlapped to each other as described above, the rack teeth  213  of the mode slider  210  and the rack teeth  251  of the loading slider  220  are disposed in such a manner as to be moved along the same locus as viewed from above; and the projecting rib  256  formed on the rack formation portion  250  of the loading slider  220  is positioned along the left side of the left side edge of the rack formation portion  211  of the mode slider  210 , and the cam portion  216  formed on the mode slider  210  is positioned on the movement locus of the slits  252  and  261  of the loading slider  220 . 
   In the state in which the mode slider  210  and the loading slider  220  are located at the rear ends of the movement ranges, that is, at the initial positions (see  FIGS. 40  to  43 ), the rack teeth  251  of the loading slider  220 , which are positioned on the upper side, are substantially overlapped to the rack teeth  213  of the mode slider  210 , which are positioned on the lower side. At this time, since the rack teeth  251  of the loading slider  220  are longer than the rack teeth  213  of the mode slider  210 , the front end portions of the rack teeth  251  of the loading slider  220  project forwardly from the front ends of the rack teeth  213  of the mode slider  210  (see FIG.  43 ). Also, the cam portion  216  of the mode slider  210  is positioned in the slits  252  and  261  of the loading slider  220 , and the lock pin  231  of the lock piece  230  is engaged in the engagement cutout  214  of the mode slider  210  to lock the mode slider  210  at the initial position. Further, the projecting rib  256  of the loading slider  220  is positioned on the left side of the opening of the engagement cutout  214  for preventing the slip-off of the lock pin  231  from the engagement cutout  214 . 
   Further, the restricting piece  144   a  formed on the connecting member  140  of the cartridge holder  120  is placed on the front end portion  216   a  of the cam portion  216  of the mode slider  210  disposed at the initial position, whereby the cartridge holder  120  is positioned at the rear end of the movement range of the mode slider  210 . At this time, the engagement projection  157   a  provided on the connecting piece  157  of the carrying slider  150  of the cartridge holder  120  is engaged in the connecting groove  264   a  formed in the connecting column  264  of the loading slider  220 . 
   A disk rotation drive mechanism  270  is disposed at an approximately central portion of the base chassis  110 . The disk rotation drive mechanism  270  includes a spindle motor  271  fixed on the base chassis  110 , and a turn table  272  fixed on an upper end portion of a spindle shaft  271   a  of the spindle motor  271 . A circular base portion  272   a , which is to be fitted in the circular fitting recess  11   b  formed in the back surface of the core  11  of the magneto-optical disk  10 , is formed on the upper surface of the turn table  272 . An annular chucking magnet  273  is fixedly buried in the upper surface of the base portion  272   a.    
   The main body of the recording and/or reproducing apparatus will be described in detail with reference to  FIGS. 25  to  28 . 
   An optical pickup mechanism  280  is disposed on the base chassis  110  at a position offset rightwardly from the disk rotation drive mechanism  270 . The optical pickup mechanism  280  has an optical pickup apparatus  281  and a thread mechanism  285  for moving the optical pickup apparatus in the lateral direction, that is, in the direction GH. 
   The optical pickup apparatus  281  includes an objective lens  283  and other optical components disposed on a slide base  282 . A guide shaft  284  extending in the lateral direction is disposed on a portion, slightly offset forwardly from an approximately intermediate portion in the longitudinal direction, of an approximately right half of the upper surface of the base chassis  110 . A front end portion of the slide base  282  is slidably supported by the guide shaft  284 . Upper and lower sliding pieces  282   a  project rearwardly from a rear end portion of the slide base  282 . The sliding pieces  282   a  are disposed in a state in which they hold, from above and below, a rear side opening edge  118   a  of an opening portion  118  formed in a rear end portion of the right half of the base chassis  110  in such a manner as to be slidable in the lateral direction. A rack portion  282   b  is formed on a front end portion of the slide base  282 . 
   The tread mechanism  285  includes a pinion  286  meshed with the rack portion  282   b , a thread motor  287 , and a transmission gear row  288  for transmission the rotation of the thread motor  287 . 
   A loading drive portion  290  for moving the mode slider  210  and the loading slider  220  is provided on the base chassis  110 . The loading drive mechanism  290  includes a pinion  291  for moving the mode slider  210  and the loading slider  220 , a drive motor  292 , and a transmission gear row  293  for transmitting the rotation of the drive motor  292  to the pinion  291 . 
   The pinion  291  has a width which allows the pinion  291  to be meshed with the rack teeth  213  of the mode slider  210  and the rack teeth  251  of the loading slider  220 . The pinion  291  is located at a position at which the pinion  291  is slightly in front of the front ends of the rack teeth  213  of the mode slider  210  at the initial position and is meshed with the front end portions of the rack teeth  251  of the loading slider  220  at the initial position. 
   As described above, when the disk cartridge  1  is inserted in the cartridge holder  120  in the normal orientation, the locking of the carrying slider  150  to the cartridge holder  120  at the standby position is released, and when the disk cartridge  1  is further inserted in the cartridge holder  120 , the carrying slider  150  is pushed by the disk cartridge  1  to be moved forwardly. When the carrying slider  150  is slightly moved forwardly from the standby position, such movement is detected by the sensor (not shown), and the drive motor  292  of the loading drive portion  290  is driven in the loading direction on the basis of the detection result of the sensor. As a result, the pinion  291  is rotated clockwise as viewed from above via the transmission gear row  293 . In addition, when the carrying slider  150  is pushed by the disk cartridge  1  to be moved forwardly, a forward movement force is applied to the loading slider  220  because the loading slider  220  is connected to the carrying slider  150  via the connecting piece  157  of the carrying slider  150  and the connecting column  264  of the loading slider  220 . In this case, the loading slider  220  is of a double structure in which the limiter portion  260  is overlapped to the rack formation portion  250  and is connected thereto via the limiter spring  267 , and accordingly, when the carrying slider  150  is moved forwardly, the limiter spring  267  is extended and thereby only the limiter portion  260  is moved forwardly, with a result that forcible rotation of the pinion  291  via the rack teeth  251 , meshed with the pinion  291 , of the rack formation portion  250  can be prevented. 
   When the pinion  291  is rotated clockwise, the loading slider  220  having the rack teeth  251  meshed with the pinion  291  is moved forwardly, that is, in the direction E. When the loading slider  220  is moved forwardly, the carrying slider  150  connected to the loading slider  220  is moved forwardly. When the carrying slider  150  is moved forwardly, the engagement projections  183   b  and  193  provided on the carrying slider  150  are engaged in the left and right cutouts  9  of the disk cartridge  1 , whereby the disk cartridge  1  whose left and right sides are held by the carrying slider  150  is carried forwardly, that is, toward the depth of the cartridge holder  120 . During a period in which the disk cartridge  1  is carried toward the depth of the cartridge holder  120 , the shutter opening piece  161  of the shutter opening/closing member  160  enters in the groove  7  of the disk cartridge  1  to release the locking of the shutter  6  at the close position, and the rear tilt edge of the shutter closing piece  162  rides on the right side of the intermediate portion  6   c  of the shutter  6  to be engaged in the engagement hole  6   d  formed in the intermediate portion  6   c  of the shutter  6 . When the disk cartridge  1  is further carried toward the depth of the cartridge holder  120 , since the front end of the intermediate portion  6   c  of the shutter  6  is pushed relatively, rearwardly by the shutter opening piece  161 , the shutter  6  is moved toward the open position. 
   Immediately before the carrying slider  15  reaches the deepest withdrawal position, the projecting piece  265  of the loading slider  220  is brought into contact with the rear end of the front side piece  211   b  to be pushed of the mode slider  210 , and the projecting rib  256  of the loading slider  220  is moved forwardly from the position at which it blocks the engagement cutout  214  of the mode slider  210  (see FIGS.  44  and  45 ). Accordingly, during a period in which the carrying slider  150  is further moved up to the withdrawal position, the mode slider  210  is pulled forwardly by the loading slider  220  via the projecting rib  265  of the loading slider  220  and the front side piece  211   b  to be pushed of the mode slider  210 , to be moved forwardly while the lock pin  231  of the lock piece  230  is removed outwardly from the engagement cutout  214 . The mode slider  210  thus becomes a state immediately before the rack teeth  213  are meshed with the pinion  291  of the loading drive portion  290  (see FIG.  45 ). On the other hand, when the carrying slider  150  reaches the withdrawal position (see FIG.  19 ), the rack teeth  251  of the loading slider  220  are moved forwardly from the pinion  291 , that is, the meshing of the rack teeth  251  with the pinion  291  is released, so that the forward movement of the loading slider  220  is stopped. 
   The loading of the disk cartridge  1  in the main body of the recording and/or reproducing apparatus is performed by forward movement of only the mode slider  210 . Such loading of the disk cartridge  1  will be described with reference to  FIGS. 46  to  49 . As the mode slider  210  is moved forwardly, the cam portion  216  integrally formed on the mode slider  210  is also moved forwardly, so that the restricting piece  144   a  formed on the connecting member  140  of the cartridge holder  120  is moved on the cam portion  216  from the rear end portion  216   a  to an approximately central portion of the tilt portion  216   b  (see FIG.  47 ). As a result, the connecting member  140  is turned, by the biasing force of the tensile coil spring  116 , around the pins  142   b  and  143   b  supported by the supporting pieces  111  of the base chassis  110  in such a manner that the front end of the connecting member  140  is moved downwardly. The upper surface of the main support  130  of the cartridge holder  120  is pushed downwardly by the front end of the main portion  141  of the connecting member  140  turned downwardly. The main support  130  is thus moved downwardly with the left and right sliding pins  136  being guided in the guide grooves  112   a  of the guide columns  112  of the base chassis  110  and with the connecting piece  137  at the front end being guided in the engagement sliding hole  113   a  of the engagement piece  113  formed on the front end portion of the base chassis  110 . Accordingly, the disk cartridge  1  supported by the cartridge holder  120  is moved downwardly together with the main support  130  (see FIG.  47 ). In this way, the turn table  272  of the disk rotation drive mechanism  270  relatively enters in the cartridge case  2  via the insertion port  3  of the disk cartridge  1  moved downwardly; the base portion  272   a  of the turn table  272  is fitted in the fitting recess  11   b  of the core  11  mounted at the central portion of the magneto-optical disk  10 ; and the core  11  is attracted by the chucking magnet  273  buried in the upper surface of the base portion  272   a , whereby the magneto-optical disk  10  is mounted on the turn table  272 . 
   The loading of the disk cartridge  1  including the withdrawal of the disk cartridge  1  in the main body of the recording and/or reproducing apparatus and the mounting of the magneto-optical disk  10  in the disk rotation drive mechanism  270  is thus ended. 
   The positions of the mode slider  210  and the loading slider  220  in the loading ended state are referred to as “loading ended positions”. 
   In the case of reproducing signals from the magneto-optical disk  10 , immediately after the loading of the disk cartridge  1  is ended as described, the spindle motor  271  is driven, to rotate the magneto-optical disk  10 , and the optical pickup apparatus  281  is operated while being moved in the lateral direction, to irradiate a signal recording plane of the magneto-optical disk  10  with laser light and detect the light returned from the signal recording plane, whereby signals are reproduced from the magneto-optical disk  10 . 
   The action of the recording and/or reproducing apparatus from the loading ended position to a recording position will be described with reference to  FIGS. 38 and 39 , and  FIGS. 50  to  55 . 
   In the case of recording signals on the magneto-optical disk  10 , the mode slider  210  is further moved forwardly, and an overwriting magnetic head enters in the cartridge case  2  via a head insertion port  5 , to be in contact with or in proximity to the back side (upper surface) of a portion, opposed to the objective lens  283 , of the magneto-optical disk  10 . 
   An overwriting head mechanism  300  provided on the base chassis  110  will be described in detail with reference to  FIGS. 38 and 39 . 
   The overwriting head mechanism  300  has a connecting base body  310 . The connecting base body  310  made from a synthetic resin is formed into a plate shape extending substantially in the vertical direction. The connecting base body  310  integrally includes a connecting portion  311  having a lower end portion fixed to a front end portion of the slide base  282  of the optical pickup apparatus  281 , a head supporting portion  312  projecting rearwardly from the upper end of the connecting portion  311 , and a restricting arm  313  projecting rearwardly from a right end portion of an upper end portion of the connecting portion  311 . A contact portion  313   a  projecting leftwardly is formed on a rear end portion of the restricting arm  313 . 
   A magnetic head device  320  is supported on the head supporting portion  312  of the connecting base body  310 . The magnetic head device  320  includes a head supporting arm  322  for supporting, on its tip side, a magnetic head  321 , and an arm supporting plate  323  for supporting the back side of the head supporting arm  322 . The head supporting arm  322  is formed by punching an elastic thin metal plate made from phosphor bronze. The head supporting arm  322  integrally includes a base portion  322   a , an arm portion  322   b  projecting rearwardly from the base portion  322   a , and an elastic portion  322   c  projecting rearwardly leftwardly from a left end portion of the base portion  322   a . The elastic portion  322   c  is shorter than the arm portion  322   b . The base portion  322   a  is fixed on the upper surface of the head supporting portion  312  of the connecting base portion  310 ; the arm portion  322   b  and the elastic portion  322   c  are tilted rearwardly, downwardly; and the magnetic head  321  is supported on the tip portion of the arm portion  322   b.    
   The arm supporting plate  323  made from a synthetic resin extends longer in the longitudinal direction. A portion, near the front end, of the arm supporting plate  323  is vertically turnably supported on the left side surface of a tip portion of the head supporting portion  312  of the connecting base body  310 . A supporting piece  323   a  projecting rightwardly is formed on the rear end of the arm supporting plate  323 . The supporting piece  323   a  supports the back surface of a tip portion of the arm portion  322   b  of the head supporting arm  322 . A pressing piece  323   b  projects rightwardly from the upper surface of the portion, turnably supported by the head supporting portion  312 , of the arm supporting plate  323 . The pressing piece  323   b  presses, from above, the base portion  322   a  of the head supporting arm  322 . A spring catch piece  323   c  is formed on a portion, slightly offset rearwardly from the portion turnably supported, of the arm supporting plate  323 . A tip portion of the elastic portion  322   c  of the head supporting arm  322  is brought into elastic-contact with the upper surface of the spring catch piece  323   c . Since the elastic portion  322   c  of the head supporting arm  322  is brought into elastic-contact with the spring catch piece  323   c  and the arm portion  322   b  of the head supporting arm  322  is brought into elastic-contact with the supporting piece  323   a , the arm supporting plate  323  is biased such that a rear end portion thereof is moved downwardly. A piece  323   d  to be operated projects downwardly from a front end portion of the arm supporting plate  323 . The piece  323   d  is viewed as L-shaped from the right side. 
   A head shift plate  330  is vertically turnably disposed on a right side portion of a front end portion of the base chassis  110 . The head shift plate  330  made from a synthetic resin is formed into a plate shape longer in the approximately lateral direction. Pieces  331  to be supported, projecting forwardly from left and right side ends of the head shift plate  330  are vertically turnably supported on the front end portion of the base chassis  110 . An operating pin  332  projects leftwardly from the left side edge of the head shift plate  330 . The operating pin  332  is placed on the upper edge of the cam portion  217  formed on the mode slider  210 . In addition, an auxiliary piece  217   d  is positioned immediately over the operating pin  332  placed on the upper edge of the cam portion  217  for preventing the operating pin  332  from being removed from the upper edge of the cam portion  217 . A restricting piece  333  projects upwardly from the rear edge of the head shift plate  330 . The restricting piece  333  is viewed substantially as inverse L-shaped from the right side. The piece  323   d  to be operated of the arm supporting plate  323  of the magnetic head device  320  is brought into elastic-contact with the back surface of an upper side  333   a  of the restricting piece  333 . 
   During a period in which the mode slider  210  is moved from the initial position to the loading ended position, the operating pin  332  of the head shift plate  330  is kept as placed on the low level portion  217   b  of the cam portion  217  formed on the mode slider  210 . As a result, the rear end of the head shift plate  330  is kept as located on the lower side. Accordingly, the rear end of the arm supporting plate  323  whose piece  323   d  pushed downwardly by the restricting piece  333  of the head shift plate  330  is kept as located on the upper side, and the rear end portion, whose back surface is supported by the supporting piece  323   a  of the arm supporting plate  323 , of the arm portion  322   b  of the head supporting arm  322  is kept as located on the upper side. Consequently, the magnetic head  321  supported by the rear end portion of the arm portion  322   b  of the head supporting arm  322  is located at a position being not in contact with or in proximity to the magneto-optical disk  10 . 
   In the case of recording signals on the magneto-optical disk  10 , the mode slider  210  is further moved forwardly from the loading ended position. As the mode slider  210  is further moved forwardly from the loading ended position, the operating pin  332  of the head shift plate  330  is relatively moved on the upper edge of the cam portion  217  from the low level portion  217   b  to the tilt portion  217   c  (see FIG.  54 ). As the operating pin  332  is moved on the tilt portion  217   c  toward the high level portion  217   a , the rear end portion of the head shift plate  330  is pushed up via the operating pin  332 , whereby the restricting piece  333  is moved upwardly. Accordingly, the arm supporting plate  323  is turned by the biasing force applied thereto in such a manner that the rear end portion thereof is moved downwardly, and thereby the rear end portion of the arm portion  322   b  of the head supporting arm  322  is moved downwardly and the magnetic head  321  supported by the rear end portion of the arm portion  322   b  is also moved downwardly (see FIG.  54 ). When the operating pin  332  of the head shift plate  330  reaches the high level portion  217   a  of the cam portion  217 , the magnetic head  321  is located at the lowest position. In such a lowest position, the magnetic head  321  enters in the cartridge case  2  through the head insertion port  5  of the disk cartridge  1 , to be thus in contact with or in proximity to a portion, to be irradiated with laser light emitted from the optical pickup mechanism  280 , of the upper surface of the magneto-optical disk  10 . In such a state, new signals are recorded on the signal recording plane of the magneto-optical disk  10  by irradiating the signal recording plane of the magneto-optical disk  10  with laser light having an intensity larger than that used for reproducing by the optical pickup mechanism  280  and also imparting a magnetic field to the signal recording plane of the magneto-optical disk  10  by the magnetic head  321 . The recording of new signals is performed by moving the optical pickup mechanism  280  in the radial direction of the magneto-optical disk  10  and also moving the magnetic head  321  together with the optical pickup mechanism  280 . 
   After the recording of new signals on the magneto-optical disk  10  is ended, the drive motor  292  of the loading drive portion  290  is driven in the unloading direction, to rotate the pinion  291  counterclockwise as viewed from above via the transmission gear row  293 . As a result, the mode slider  210  whose rack teeth  213  are meshed with the pinion  291  is first moved rearwardly, that is, toward the above-described loading ended position. As the mode slider  210  is moved toward the loading ended position, the operating pin  332  of the head shift plate  330  is moved on the upper edge of the cam portion  217  of the mode slider  210  from the high level portion  217   a  to the low level portion  217   b  via the tilt portion  217   c , whereby the head shift plate  330  is turned downwardly and the restricting piece  333  is moved downwardly. Accordingly, the piece  323   d  to be operated of the arm supporting plate  323  is pushed downwardly by the upper side  333   a  of the restricting piece  333 , and thereby the arm supporting plate  323  is turned such that the rear end thereof is moved upwardly. The rear end portion of the arm portion  322   b  of the head supporting arm  322  is moved upwardly by the supporting piece  323   a  of the arm supporting plate  323  turned with its rear end moved upwardly. As a result, the magnetic head  321  supported by the rear end portion of the arm portion  322   b  of the head supporting arm  322  is moved upwardly, to be thus separated upwardly from the upper surface of the magneto-optical disk  10 . In addition, if a forward movement force is further applied to the rear end portion of the arm portion  322   b  of the head supporting arm  322  made from an elastic material for some reason, since the contact portion  313   a  of the restricting arm  313  of the connecting base body  310  is positioned immediately over the rear end portion of the arm portion  322   b  of the head supporting arm  322  and the rear end portion of the arm portion  322   b  of the head supporting arm  322  is brought into contact with the contact portion  313   a , the rear end portion of the arm portion  322   b  is prevented from being excessively moved upwardly. 
   In this way, during the period in which the mode slider  210  is moved from the front end of the movement range to the loading ended position, the magnetic head  321  is separated from the upper surface of the magneto-optical disk  10  and is removed upwardly from the cartridge case  2  to be returned to the standby position. 
   The ejection of the disk cartridge  1  will be described in detail below. 
   When the operation for ejecting the disk cartridge  1 , that is, the ejecting operation is performed, the drive motor  292  of the loading drive portion  290  is driven in the unloading direction, to rotate the pinion  291  counterclockwise as viewed from above via the transmission gear row  293 . With this rotation of the pinion  291 , the mode slider  210  whose rack teeth  213  are meshed with the pinion  291  is first moved rearwardly, that is, toward the initial position. As the mode slider  210  is moved toward the initial position, the restricting piece  144   a  of the connecting member  140  of the cartridge holder  120  reaches the rear end portion  216   b  of the cam portion  216  via the tilt portion  216   a  of the other cam portion  216  of the mode slider  210 . When the restricting piece  144   a  reaches the rear end portion  216   b  of the cam portion  216  via the tilt portion  216   a  of the cam portion  216 , the connecting member  140  is turned against the biasing force of the tensile coil spring  116  such that the front end thereof is moved upwardly, and the back surface of the portion, near the rear end, of the main support  130  of the cartridge holder  120  is pushed upwardly by the front end of the connecting member  140 . As a result, the main support  130  is moved upwardly. Along with the upward movement of the main support  130  of the cartridge holder  120 , the core  11  of the magneto-optical disk  10  is separated upwardly from the turn table  272  of the disk rotation drive mechanism  270 . 
   When the mode slider  210  is moved up to a position immediately before the initial position, the rear end of the front side piece  211   b  to be pushed of the mode slider  210  is brought into contact with the front edge of the projecting rib  265  of the loading slider  220 . As the mode slider  210  is moved from such a position to the initial position, the loading slider  220  is slightly moved rearwardly and thereby the rack teeth  251  of the loading slider  220  are meshed with the pinion  291  of the loading drive portion  290 , and further, the lock pin  231  of the lock piece  230  is pushed leftwardly by the tilt surface  256   b  at the rear end of the projecting rib  256  of the loading slider  220  to be engaged in the engagement cutout  214  of the mode slider  210 , whereby the mode slider  210  is locked at the initial position. After that, the loading slider  220  whose rack teeth  251  are meshed with the pinion  291  is moved rearwardly, that is, toward the initial position by the rotation of the pinion  291 . 
   As the loading slider  220  is moved toward the initial position, the carrying slider  150  connected to the loading slider  220  via the connecting column  264  and the connecting piece  157  is moved rearwardly, that is, toward the standby position. During the period in which the carrying slider  150  is moved toward the standby position, the shutter  6 , located at the open position, of the disk cartridge  1 , is relatively pulled forwardly by the shutter closing piece  162  engaged in the engagement hole  6   d , to be moved to the close position. When the shutter  6  is returned to the close position, the front side tilt edge  162   a  of the shutter closing piece  162  is slid on the front side opening edge of the engagement hole  6   d  to be moved rightwardly, with a result that the engagement of the shutter closing piece  162  in the engagement hole  6   d  is released. The shutter closing piece  162  is further slid on the outer (right) side surface of the intermediate portion  6   c  of the shutter  6  to be relatively moved forwardly, and then removed from the shutter  6 . When the carrying slider  150  reaches the standby position, the loading slider  220  also reaches the initial position, and the drive motor  292  of the loading drive portion  290  is stopped. 
   When the carrying slider  150  reaches the standby position, most of the disk cartridge  1  excluding the front end portion projects from the rear end of the cartridge holder  120 . When the disk cartridge  1  is pulled out of the cartridge holder  120  by an operator gripping the projecting portion thereof with his or her fingers, the engagement projection  183   b  of the lock lever  180  and the engagement projection  193  of the click member  190  are removed from the cutouts  9  of the disk cartridge  1 . In this way, the disk cartridge  1  can be easily pulled out of the cartridge holder  120 . 
   When the disk cartridge  1  is pulled out of the cartridge holder  120 , the lock lever  180  is turned clockwise as viewed from above, that is, in the direction CW, so that the lock pin  181   a  of the first arm piece  181  is engaged in the lock portion  132   a  formed at the rear end of the sliding groove  132  of the main support  130 ; the lock projection  193   a  of the third arm piece  183  is engaged in the engagement hole  130   d  formed in the left side wall  130   c ; and the lock member  170  is turned downwardly and thereby the lock claw  173  of the lock member  170  is engaged in the hole  156   a  to be locked of the carrying slider  150 , whereby the carrying slider  150  is locked at the standby position. 
   While the preferred embodiments of the present invention have been described using the specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.