Abstract:
Disclosed herein is an optical storage device including an optical head having an objective lens for focusing a light beam from a light source onto an optical recording medium accommodated in a cartridge shell, and a photodetector for detecting a regenerative signal from reflected light from the optical recording medium. The optical storage device further includes a cartridge holder having a main surface for holding a cartridge inserted in the optical storage device. First and second cartridge holding assemblies are mounted on the main surface of the cartridge holder in the vicinity of a first side thereof in such a manner as to be spaced from each other and to partially project into the cartridge holder. A third cartridge holding assembly is mounted on the main surface of the cartridge holder in the vicinity of a second side thereof opposite to the first side so as to partially project into the cartridge holder. Each cartridge holding assembly includes a cartridge holding member having a flat surface for holding the cartridge shell.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an optical storage device, and more particularly to a cartridge holding mechanism for an optical storage device. 
     2. Description of the Related Art 
     An optical disk has received attention as a memory medium that becomes a core in the recent rapid development of multimedia, and it is usually accommodated in a cartridge case to be provided as an optical disk cartridge for practical use. The optical disk cartridge is loaded into an optical disk drive to perform reading/writing of data (information) from/to the optical disk by means of an optical pickup (optical head). A recent optical disk drive intended to realize size reduction is composed of a fixed optical assembly including a laser diode module, a polarization beam splitter for reflecting and transmitting a laser beam, and a photodetector for receiving reflected light from an optical disk, and a movable optical assembly including a carriage and an optical head having an objective lens and a beam raising mirror mounted on the carriage. 
     The carriage is movable in the radial direction of the optical disk along a pair of rails by means of a voice coil motor. A write-power laser beam emitted from the laser diode module of the fixed optical assembly is first collimated by a collimator lens, next transmitted by the polarization beam splitter, next reflected by the beam raising mirror of the optical head, and finally focused on the optical disk by the objective lens, thereby writing data onto the optical disk. On the other hand, data reading is performed by directing a read-power laser beam onto the optical disk. Reflected light from the optical disk is first collimated by the objective lens, next reflected by the polarization beam splitter, and finally detected by the photodetector, thereby converting the detected optical signal into an electrical signal. 
     In general, a cartridge holder is used to hold the optical disk cartridge in the optical disk drive. Further, a spring mechanism as an independent component for firmly holding the cartridge is mounted on the cartridge holder, so as to prevent the play (rattling) of the cartridge in the cartridge holder due to vibration or shock. However, the optical disk is a removable medium, and there are slight variations in size of the cartridge, differences in material of the cartridge, and differences in surface finished condition of the cartridge due to differences in cartridge maker. According to these differences and differences in use frequency (the number of insertions and ejections) of the cartridge, there occur variations in frictional force generated between the cartridge surface and the cartridge holder or another sliding member such as a drive base in the optical disk drive. Accordingly, even in the same optical disk drive, the amount of ejection of the cartridge tends to vary because of such variations in frictional force. 
     To suppress such variations in the amount of ejection of the cartridge, the conventional cartridge holding mechanism is provided with means for minimizing a change in elastic force of the spring mechanism for holding the cartridge, or provided with a hook mechanism or brake mechanism for stopping or braking the cartridge during ejection. However, such a conventional cartridge holding mechanism employing a spring mechanism as an independent component has a problem of cost increase due to an increase in parts count, an increase in man-hour for parts mounting, and an increase in man-hour for parts managing, for example. 
     There is a recent trend that a semitransparent cartridge shell (case) is adopted to make the cartridge fashionable. Further, while the conventional cartridge shell is formed of polycarbonate, there is a tendency that the recent cartridge shell is formed of ABS resin lower in hardness than polycarbonate. That is, the hardness of polycarbonate is 120 and the hardness of ABS resin is 103 as measurements by Rockwell ASTMD785, R scale representation. 
     However, such a semitransparent cartridge shell tends to show noticeable scratches. Further, in the case that the semitransparent cartridge shell is formed of ABS resin lower in hardness than polycarbonate, the scratches becomes more noticeable. Accordingly, in inserting or ejecting an optical disk cartridge having the semitransparent cartridge shell into or from an optical disk drive, the surface of the cartridge shell may be scratched by a mechanism (including springs in many cases) for holding the cartridge, causing a problem that the appearance of the cartridge is deteriorated by the repetition of insertion/ejection of the cartridge with respect to the optical disk drive. 
     Further, when inserting the optical disk cartridge into the optical disk drive, a shutter of the optical disk cartridge is opened by a shutter opening/closing mechanism including a slider and a torsion spring, thereby exposing an optical disk accommodated in the cartridge shell. In the conventional shutter opening/closing mechanism, an engaging portion between the slider and the torsion spring is spaced apart from a slide portion on which the slider slides, so that a large bending moment is produced in sliding the slider. Accordingly, in the case that burrs or the like are present on the slide portion, a sliding load on the slider increases to cause a possibility that stable insertion/ejection of the cartridge is difficult to obtain. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a cartridge holding mechanism for an optical storage device which can stably hold a cartridge in the optical storage device and can prevent a cartridge shell from being scratched in inserting or ejecting the cartridge with respect to the optical storage device. 
     It is another object of the present invention to provide a cartridge holding mechanism for an optical storage device which can obtain a stable frictional force in ejecting a cartridge from the optical storage device. 
     It is a further object of the present invention to provide a shutter opening/closing mechanism for a cartridge which can effect stable insertion and ejection of the cartridge with respect to an optical storage device. 
     In accordance with an aspect of the present invention, there is provided a storage device capable of accepting a cartridge including a cartridge shell and a recording medium accommodated in the cartridge shell, and reading information recorded on the recording medium, comprising a cartridge holder having a main surface for holding the cartridge inserted in the storage device, the main surface having first and second openings spaced from each other in the vicinity of a first side of the cartridge holder and a third opening in the vicinity of a second side of the cartridge holder opposite to the first side; and first, second, and third cartridge holding assemblies mounted on the cartridge holder so as to partially project from the first, second, and third openings into the cartridge holder, respectively; each of the first, second, and third cartridge holding assemblies including a cartridge holding member having a flat surface for holding the cartridge shell, a cover fixed to the cartridge holder, and an elastic member interposed between the cartridge holding member and the cover. 
     The cartridge holding member and the elastic member may be integrally formed from a leaf spring. Preferably, the flat surface of the cartridge holding member has a reduced surface roughness provided by surface treatment. 
     In accordance with another aspect of the present invention, there is provided a cartridge holding mechanism for a storage device, comprising a base; a cartridge holder having a main surface for holding a recording medium cartridge inserted in the storage device in cooperation with the base, the main surface having first and second openings spaced from each other in the vicinity of a first side of the cartridge holder and a third opening in the vicinity of a second side of the cartridge holder opposite to the first side; and first, second, and third cartridge holding assemblies mounted on the cartridge holder so as to partially project from the first, second, and third openings into the cartridge holder, respectively; each of the first, second, and third cartridge holding assemblies comprising a cartridge holding member having a flat surface for holding the recording medium cartridge, a cover fixed to the cartridge holder, and an elastic member interposed between the cartridge holding member and the cover. 
     In accordance with a further aspect of the present invention, there is provided a storage device capable of accepting a cartridge including a cartridge shell and a recording medium accommodated in the cartridge shell, and reading information recorded on the recording medium, comprising a cartridge holder having a main surface for holding the cartridge inserted in the storage device, the main surface having first and second openings spaced from each other in the vicinity of a first side of the cartridge holder and a third opening in the vicinity of a second side of the cartridge holder opposite to the first side; a first spring arm having a first portion extending over the first opening, a second portion extending over the second opening, and an intermediate portion extending between the first portion and the second portion, the first spring arm being fixed to the cartridge holder at the intermediate portion so as to extend substantially in parallel to the first side of the cartridge holder; and a second spring arm extending over the third opening substantially in parallel to the second side of the cartridge holder, the second spring arm being fixed at one end portion thereof to the cartridge holder; the first and second portions of the first spring arm having first and second projecting portions, respectively, the second spring arm having a third projecting portion at the other end portion; each of the first, second, and third projecting portions having a flat surface for holding the cartridge shell. 
     Preferably, the first and second projecting portions are integral with the first spring arm, and the third projecting portion is integral with the second spring arm. The flat surface of each projecting portion has a reduced surface roughness provided by surface treatment. 
     In accordance with a still further aspect of the present invention, there is provided a cartridge holding mechanism for a storage device, comprising a base; a cartridge holder having a main surface for holding a recording medium cartridge inserted in the storage device in cooperation with the base, the main surface having first and second openings spaced from each other in the vicinity of a first side of the cartridge holder and a third opening in the vicinity of a second side of the cartridge holder opposite to the first side; a first spring arm having a first portion extending over the first opening, a second portion extending over the second opening, and an intermediate portion extending between the first portion and the second portion, the first spring arm being fixed to the cartridge holder at the intermediate portion so as to extend substantially in parallel to the first side of the cartridge holder; and a second spring arm extending over the third opening substantially in parallel to the second side of the cartridge holder, the second spring arm being fixed at one end portion thereof to the cartridge holder; the first and second portions of the first spring arm having first and second projecting portions, respectively, the second spring arm having a third projecting portion at the other end portion; each of the first, second, and third projecting portions having a flat surface for holding the cartridge. 
     In accordance with a still further aspect of the present invention, there is provided a storage device capable of accepting a cartridge including a cartridge shell and a recording medium accommodated in the cartridge shell, and reading information recorded on the recording medium, comprising a cartridge holder having a main surface for holding the cartridge inserted in the storage device, the main surface having a guide groove having a first portion inclined with respect to a side edge of the cartridge holder and a second portion parallel to the side edge of the cartridge holder; first and second sliders slidably fitted with the guide groove; a first spring having one end engaged with the first slider and the other end engaged with the second slider; and a second spring having one end engaged with the second slider and the other end engaged with the cartridge holder; the first slider being biased by the first and second springs in a direction of ejecting the cartridge inserted in the cartridge holder; an engaging portion between the first slider and the first spring being formed at substantially the same level as that of a slide portion on which the first slider slides. 
     In accordance with a still further aspect of the present invention, there is provided a shutter opening/closing mechanism for a cartridge having a shutter, comprising a cartridge holder having a main surface for holding the cartridge inserted in a storage device, the main surface having a guide groove having a first portion inclined with respect to a side edge of the cartridge holder and a second portion parallel to the side edge of the cartridge holder; first and second sliders slidably fitted with the guide groove; a first spring having one end engaged with the first slider and the other end engaged with the second slider; and a second spring having one end engaged with the second slider and the other end engaged with the cartridge holder; the first slider being biased by the first and second springs in a direction of ejecting the cartridge inserted in the cartridge holder; an engaging portion between the first slider and the first spring being formed at substantially the same level as that of a slide portion on which the first slider slides. 
     The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an upper perspective view of a magneto-optical disk drive including a cartridge holding mechanism according to the present invention; 
     FIG. 2 is a lower perspective view of the magneto-optical disk drive; 
     FIG. 3A is a perspective view of a magneto-optical disk cartridge in a shutter closed condition; 
     FIG. 3B is a perspective view of the magneto-optical disk cartridge in a shutter open condition; 
     FIG. 4 is a top plan view of the magneto-optical disk drive in the condition where the magneto-optical disk cartridge is slightly inserted in the magneto-optical disk drive or the cartridge is ejected from the magneto-optical disk drive; 
     FIG. 5 is a back side view of FIG. 4; 
     FIG. 6 is a right side view of FIG. 5; 
     FIG. 7 is a view similar to FIG. 4 with magnetic circuits, a carriage, and an optical head shown by broken lines; 
     FIG. 8 is a top plan view of a cartridge holder; 
     FIG. 9 is a right side view of FIG. 8; 
     FIG. 10 is a back side view of FIG. 8; 
     FIG. 11 is a cross section taken along the line  11 — 11  in FIG. 8; 
     FIG. 12A is a perspective view of a cartridge holding member shown in FIG. 11; 
     FIG. 12B is a perspective view showing a modification of the cartridge holding member; 
     FIG. 13 is a top plan view showing another preferred embodiment of the cartridge holder; 
     FIG. 14 is a cross section taken along the line  14 — 14  in FIG. 13; 
     FIG. 15A is a fragmentary perspective view of a first spring arm shown in FIG. 13; 
     FIG. 15B is a view taken in the direction of an arrow  15 B shown in FIG. 15A; 
     FIG. 15C is a view taken in the direction of an arrow  15 C shown in FIG. 15A; 
     FIG. 16A is a perspective view showing a structure of engagement between a first slider and a first torsion spring; 
     FIG. 16B is a view taken in the direction of an arrow  16 B shown in FIG. 16A with slide portions being shown in cross section; 
     FIGS. 17A and 17B are views similar to FIG. 16B, showing other preferred embodiments of the first slider; 
     FIG. 18 is a view similar to FIG. 16B, showing a structure of engagement between a second slider and a second torsion spring; 
     FIG. 19 is a perspective view showing a comparison of the engagement structure of the first slider and the first torsion spring; 
     FIG. 20 is a bottom plan view of the magneto-optical disk drive in the condition where the magneto-optical disk cartridge is fully inserted; and 
     FIG. 21 is a right side view of FIG.  20 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, there is shown a perspective view of a magneto-optical disk drive  10  to which the present invention is applied, as viewed from the upper side. FIG. 2 is a perspective view of the magneto-optical disk drive  10  as viewed from the lower side. The magneto-optical disk drive  10  accepts a magneto-optical disk cartridge  14  having a cartridge shell and a magneto-optical disk (both will be hereinafter described) accommodated in the cartridge shell, and performs reading/writing of data from/to the magneto-optical disk in the magneto-optical disk cartridge  14 . Reference numeral  13  denotes an eject button for ejecting the magneto-optical disk cartridge  14  out of the magneto-optical disk drive  10 . 
     As will be hereinafter described in detail, the magneto-optical disk drive  10  includes a load/eject mechanism for the magneto-optical disk cartridge  14 , a spindle motor for rotating the magneto-optical disk, a bias magnetic field generating mechanism, a positioner, a fixed optical assembly, and a movable optical assembly. The magneto-optical disk drive  10  further has an insert opening  12  for accepting the magneto-optical disk cartridge  14 . 
     FIGS. 3A and 3B are perspective views of the magneto-optical disk cartridge  14  in its different conditions, as viewed from the lower side. It should be noted that FIG. 1 shows the upper side of the magneto-optical disk cartridge  14 . As shown in FIG. 3A, the magneto-optical disk cartridge  14  has a cartridge shell (case)  16 . The cartridge shell  16  is provided with a slidable shutter  18 . A shutter opening arm  20  is mounted at a front end portion of the shutter  18 . A write protector  22  for prohibiting writing onto a magneto-optical disk is provided at a rear end portion of the cartridge shell  16 . 
     When an end portion  20   a  of the shutter opening arm  20  is pushed by a slider to be hereinafter described, the shutter  18  is slid on the cartridge shell  16 . FIG. 3B shows a condition where the shutter  18  is fully open. As shown in FIG. 3B, a magneto-optical disk  24  as a data recording medium is rotatably accommodated in the cartridge shell  16 . The magneto-optical disk  24  has a central hub  26  adapted to be chucked for rotation by a spindle motor to be hereinafter described. Two reference holes  28  and  30  for positioning the magneto-optical disk cartridge  14  in the magneto-optical disk drive  10  are formed near the opposite side edges at the rear end portion of the cartridge case  16 . The reference hole  28  is a round hole, and the reference hole  30  is an elongated hole. 
     FIG. 4 is a top plan view showing a condition where the magneto-optical disk cartridge  14  is slightly inserted in the magneto-optical disk drive  10  from the insert opening  12 . FIG. 5 is a bottom plan view showing the same condition as that of FIG. 4, and FIG. 6 is a right side view of FIG.  5 . As best shown in FIG. 5, a load plate  34  is movably mounted on a drive base  32 . The load plate  34  has four elongated holes  36   a ,  36   b ,  36   c , and  36   d . Two pins  38   a  and  38   b  and two engaging projections  40   a  and  40   b  are fixed to the drive base  32 . The pins  38   a  and  38   b  are inserted in the elongated holes  36 a and  36   b , respectively, and the engaging projections  40   a  and  40   b  are inserted in the elongated holes  36   c  and  36   d , respectively. With this structure, the load plate  34  is movable in the longitudinal direction of the base  32  as being guided by the pins  38   a  and  38   b  and the engaging projections  40   a  and  40   b.    
     Two openings  51  are formed on each side portion of the base  32 . On the other hand, the load plate  34  is integrally formed with four lift guides  46  bent about 90° from the horizontal surface. The four lift guides  46  of the load plate  34  are respectively inserted through the four openings  51  of the base  32  so as to project from the lower side of the base  32  to the upper side thereof (see FIG.  4 ). Further, a pin  50  is fixed to the base  32 . As shown in FIG. 6, each lift guide  46  has a slot  48  consisting of a horizontal portion and an inclined portion. 
     There will now be described the structure of a cartridge holder  52  according to a preferred embodiment of the present invention with reference to FIGS. 8 to  10 . Two pins  54  and a pin  56  are fixed to each side portion of the cartridge holder  52 . The cartridge holder  52  is formed with a guide groove  60 . The guide groove  60  is composed of a first portion obliquely extending from one end of the insert opening  12  laterally inward of the cartridge holder  52  and a second portion extending from an inward end of the first portion to the rear end of the cartridge holder  52  in parallel to the longitudinal direction of the cartridge holder  52 . 
     A first slider  62  and a second slider  64  are slidably engaged with the guide groove  60 . The first slider  62  and the second slider  64  are formed of resin such as triacetal. As shown in FIG. 10, the first slider  62  and the second slider  64  are connected by a torsion spring  66 , and a torsion spring  68  is interposed between the second slider  64  and the cartridge holder  52  so as to normally bias the second slider  64  toward the front end of the cartridge holder  52 . 
     The opposite edge portions of the guide groove  60  are formed as slide portions  61  on which the sliders  62  and  64  slide. The slide portions  61  are formed by drawing the cartridge holder  52  so that the surface of the cartridge holder  52  as viewed in FIG. 10 is slightly lowered. Accordingly, the slide portions  61  extending along the guide groove  60  are slightly raised as viewed in FIG. 8. A bias magnetic field generating mechanism  70  is mounted on the cartridge holder  52 . The bias magnetic field generating mechanism  70  includes a back yoke  72 , a center yoke  74  mounted on the back yoke  72 , and a coil  76 . The cartridge holder  52  and the back yoke  72  are formed from a steel plate, for example. 
     As shown in FIG. 10, four flattened projections  78  are formed on a portion of the cartridge holder  52  where the bias magnetic field generating mechanism  70  is located, in order to prevent the magneto-optical disk cartridge  14  inserted in the magneto-optical disk drive  10  from colliding with the cartridge holder  52  and/or the center yoke  74 . A first opening  81  and a second opening  83  are formed through the cartridge holder  52  in the vicinity of a first side thereof. The first and second openings  81  and  83  are spaced a given distance from each other. A third opening  85  is formed through the cartridge holder  52  in the vicinity of a second side thereof opposite to the first side. 
     As shown in FIGS. 8 and 11, a first cartridge holding assembly  80  is mounted on the cartridge holder  52  so as to partially project from the first opening  81  into the cartridge holder  52 . Similarly, a second cartridge holding assembly  82  is mounted on the cartridge holder  52  so as to partially project from the second opening  83  into the cartridge holder  52 . Similarly, a third cartridge holding assembly  84  is mounted on the cartridge holder  52  so as to partially project from the third opening  85  into the cartridge holder  52 . 
     The first, second, and third cartridge holding assemblies  80 ,  82 , and  84  have the same configuration, and so the first cartridge holding assembly  80  only will now be described as a representative. As shown in FIG. 11, the first cartridge holding assembly  80  includes a cartridge holding member  86  having a projecting portion  86   a , a cover  88  fixed to the cartridge holder  52  by spot welding, and an elastic member  90  such as a coil spring interposed between the cartridge holding member  86  and the cover  88 . The cartridge holding member  86  and the cover  88  are formed from a stainless steel sheet or a galvanized steel sheet, for example. As best shown in FIG. 12A, the projecting portion  86 a of the cartridge holding member  86  has a flat surface  87  adapted to come into contact with the cartridge shell  16 . 
     It is now assumed that the cartridge shell  16  is formed of ABS resin and that it is semitransparent. Then, the conditions for preventing the cartridge shell  16  from being scratched will now be obtained. It is assumed that the weight of the cartridge  14  is about 30 g in general and that the shock resistance required in operating the cartridge  14 , that is, in inserting or ejecting the cartridge  14  into or from the disk drive  10  is 10 G (design value). Under these conditions, the cartridge holding force required to prevent the play of the cartridge  14  in the operation becomes equal to or greater than 300 gf, or 2.94 newtons (N). In the case of applying this required holding force to the cartridge  14  at three points, a cartridge holding force of 100 gf (0.98 N) is required at each point. 
     If the cartridge holding member  86  has a contact portion coming into point contact with the surface of the cartridge  14 , a cartridge holding force of 100 gf (0.98 N) or more is applied to the surface of the cartridge  14 , causing scratches on the surface of the cartridge shell  16 . However, since the contact portion of the cartridge holding member  86  is formed as the flat surface  87  in this preferred embodiment, the cartridge holding force applied to the cartridge  14  can be dispersed. 
     Assuming that the area of the flat surface  87  is 10 mm 2 , for example, the-cartridge holding force applied to the surface of the cartridge  14  is dispersed to become 10 gf/mm 2  (0.098 N/mm 2 ), thereby preventing scratches on the surface of the cartridge shell  16 . From the viewpoint of working, it is difficult to provide a so large area for the flat surface  87 , and so the area of the flat surface  87  is preferably set in the range of about 5 mm 2  to about 30 mm 2 . 
     Further, the relation between the surface roughness of the flat surface  87  and the cartridge holding force will now be examined. It is assumed that the flat surface  87  has an area of about 10 mm 2 . The condition of the surface of the cartridge shell  16  was evaluated visually by changing the cartridge holding force and the surface roughness of the flat surface  87 . The result of this evaluation is shown in Table 1. 
     
       
         
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Surface Roughness (Rz) (μm) 
               
             
          
           
               
                   
                 0.4071 
                 0.9677 
                 1.2342 
               
               
                   
                   
               
             
          
           
               
                   
                 Holding Force 
                 0.098 
                 ◯ 
                 Δ 
                 X 
               
               
                   
                 (N/mm 2 ) 
                 0.196 
                 Δ 
                 X 
                 X 
               
               
                   
                   
                 0.294 
                 X 
                 X 
                 X 
               
               
                   
                   
               
               
                   
                 * [Evaluation] 
               
               
                   
                 ◯: Not scratched; Δ: Slightly scratched; X: Scratched  
               
             
          
         
       
     
     As apparent from Table 1, the surface of the cartridge shell  16  can be less scratched by suppressing the holding force per unit area and reducing the surface roughness of the flat surface  87  of the cartridge holding member  86 . FIG. 12B shows a modification of the cartridge holding member  86 . In this modification, a cartridge holding member  86 ′ formed from a leaf spring is adopted to eliminate the need for any independent elastic member. That is, the cartridge holding member and the elastic member can be integrated. 
     Referring to FIG. 13, there is shown a top plan view of a cartridge holder  52 ′ according to another preferred embodiment of the present invention. A first opening  81 ′ and a second opening  83 ′ are formed through the cartridge holder  52 ′ in the vicinity of a first side thereof so as to be spaced a given distance from each other. A third opening  85 ′ is formed through the cartridge holder  52 ′ in the vicinity of a second side thereof opposite to the first side. Reference numeral  130  denotes a first spring arm, which has a first portion  130   a  extending over the first opening  81 ′, a second portion  130   b  extending over the second opening  83 ′, and an intermediate portion  130   c  extending between the first and second portions  130   a  and  130   b.    
     The first spring arm  130  is fixed to the cartridge holder  52 ′ by spot welding or the like at the intermediate portion  130   c  so as to extend substantially parallel to the first side of the cartridge holder  52 ′. As best shown in FIG. 14, the first portion  130   a  is formed at its front end portion with a projecting portion  132  by drawing. The projecting portion  132  projects from the first opening  81 ′ into the cartridge holder  52 ′. Similarly, the second portion  130   b  is formed at its front end portion with a projecting portion  134  by drawing. In modification, the first spring arm  130  may be divided into two parts, and each part may be fixed to the cartridge holder  52 ′ by spot welding. 
     Similarly, a second spring arm  135  is fixed at one end portion thereof to the cartridge holder  52 ′ by spot welding or the like, and extends over the third opening  85 ′ in parallel to the second side of the cartridge holder  52 ′. The second spring arm  135  is formed at its front end portion with a projecting portion  136  by drawing. 
     As shown in FIGS. 15A to  15 C, the projecting portion  132  of the first spring arm  130  has a flat surface  133 . The area of the flat surface  133  is preferably set in the range of about 5 mm 2  to about 30 mm 2 . Each of the other projecting portions  134  and  136  has a similar flat surface having an area set preferably in the range of about 5 mm 2  to about 30 mm 2 . Furthermore, each flat surface is preferably subjected to surface treatment such as chromium plating for reducing the surface roughness. Instead of chromium plating, each flat surface may be subjected to electrolytic polishing. 
     According to the cartridge holder  52 ′ of this preferred embodiment, the projecting portions  132 ,  134 , and  136  have the respective flat surfaces for holding the cartridge shell  16 . Accordingly, in inserting or ejecting the cartridge  14  into or from the disk drive according to this preferred embodiment, a stable frictional force can be obtained and the cartridge shell  16  can be prevented from being scratched. 
     A structure of engagement between the first slider  62  and the first torsion spring  66  will now be described with reference to FIGS. 16A and 16B. The first slider  62  has a pair of flanges  140  and  142 . The first slider  62  is slidably fitted with the guide groove  60  in such a manner that the slide portions  61  are interposed between the flanges  140  and  142 . The first slider  62  has an engaging hole  144  at substantially same level as that of the slide portions  61 , and one end of the first torsion spring  66  is engaged with the engaging hole  144 . 
     Thus, the engaging hole  144  of the first slider  62  as an engaging portion for engaging the first torsion spring  66  is formed at substantially the same level as that of the slide portions  61  of the cartridge holder  52  on which the first slider  62  slides, so that a bending moment by the first torsion spring  66  in sliding the first slider  62  becomes almost zero. Accordingly, even in the case that burrs or the like are present on the slide portions  61  for the first slider  62 , a sliding load on the first slider  62  is not so increased to allow stable insertion and ejection of the cartridge  14 . 
     FIGS. 17A and 17B show modifications of the first slider  62 . The modification shown in FIG. 17A is a first slider  62 A having a pair of flanges  140  and  142 . The flange  140  is integrally formed with a plurality of projections  146  kept in contact with the upper surfaces of the slide portions  61 . Similarly, the flange  142  is integrally formed with a plurality of projections  148  kept in contact with the lower surfaces of the slide portions  61 . Accordingly, a sliding load in sliding the first slider  62 A can be reduced. The modification shown in FIG. 17B is a first slider  62 B having a pair of flanges  140  and  142  respectively formed with inclined surfaces  150  and  152 . Accordingly, a sliding load in sliding the first slider  62 B can be reduced. 
     Referring to FIG. 18, there is shown a structure of engagement between the second slider  64  and the second torsion spring  68 . The second slider  64  has a pair of recesses  154 . The second slider  64  is slidably fitted with the guide groove  60  in such a manner that the slide portions  61  are inserted in the recesses  154 . The second slider  64  has an engaging hole  156  formed at substantially the same level as that of the slide portions  61 , and one end of the second torsion spring  68  is engaged with the engaging hole  156 . Although not especially shown, an engaging portion between the second slider  64  and the first torsion spring  66  is also formed at substantially the same level as that of the slide portions  61 . Accordingly, a bending moment by the first and second torsion springs  66  and  68  in sliding the second slider  64  becomes almost zero, thereby reducing a sliding load on the second slider  64 . 
     FIG. 19 shows a structure of engagement between a first slider  62 ′ and a first torsion spring  66 ′ as a comparison. In this comparison, the first slider  62 ′ has an engaging hole  144 ′ formed at a level higher by about 4.1 mm than the level of the slide portions  61 . Assuming that the force at the point of action by the first torsion spring  66 ′ is 6 gf (0.059 N), a bending moment M of 25 gf·mm (0.246 N·mm) is produced in the first slider  62 ′. This bending moment M causes inclination of the first slider  62 ′ in sliding on the slide portions  61 . Accordingly, in the case that burrs or the like are present on the slide portions  61 , a sliding load on the first slider  62 ′ increases to hinder stable insertion and ejection of the cartridge  14 . 
     In contrast to this comparison, the structure of engagement between the first slider  62  and the first torsion spring  66  according to this preferred embodiment can eliminate the above problem, because the engaging portion  144  and the slide portions  61  are set substantially the same level. Accordingly, the bending moment by the first torsion spring  66  can be almost neglected to thereby reduce the sliding load. 
     The cartridge holder  52  having the above structure is mounted on the load plate  34  in such a manner that the four pins  54  of the cartridge holder  52  are respectively inserted in the slots  48  of the four lift guides  46  of the load plate  34 , and that the two pins  56  of the cartridge holder  52  are respectively inserted in two guide slots  58  formed at the opposite side portions of the base  32 . FIG. 6 shows a condition where only a front end portion of the cartridge  14  is inserted in the cartridge holder  52 . In this condition, the pins  54  are respectively located in the horizontal portions of the slots  48  of the lift guides  46 . 
     As shown in FIGS. 5 and 7, a pair of magnetic circuits  94  and a pair of guide rails  96  are mounted on the drive base  32 . Each magnetic circuit  94  consists of a permanent magnet  91  and a yoke  92 . Reference numeral  98  denotes a carriage for carrying an optical head  100  having an objective lens  102 . The carriage  98  is provided with a pair of coils  104  at opposite positions respectively corresponding to the pair of magnetic circuits  94 . The magnetic circuits  94  and the coils  104  constitute a voice coil motor (VCM). When a current is passed through the coils  104 , the carriage  98  is guided by the guide rails  96  to move in the radial direction of the magneto-optical disk  24 . 
     A spindle motor  108  is fixed to the drive base  32 . A fixed optical assembly  110  having a laser diode  107  and a photodetector  109  is further mounted on the drive base  32 . A pair of positioning pins  112  are fixed to the drive base  32 . When the cartridge  14  is fully inserted in the magneto-optical disk drive  10 , the pins  112  are respectively inserted into the reference holes  28  and  30  of the cartridge  14  to thereby position the cartridge  14  (see FIG.  6 ). 
     An eject motor  114  is further mounted on the drive base  32  to eject the cartridge  14  out of the magneto-optical disk drive  10 . A cam  116  is connected to an output shaft of the eject motor  114 . In the unloaded condition shown in FIG. 6, the cam  116  abuts against an engaging member  118  integral with the load plate  34  to keep the load plate  34  at an unloading position moved in the direction P shown in FIG.  6 . 
     As shown in FIG. 5, a first load cam  120  is mounted on the back surface of the drive base  32  so as to be biased clockwise as viewed in FIG. 5 by a torsion spring  122 . A second load cam  124  is fixed to the first load cam  120 . As shown in FIG. 6, the first load cam  120  is integrally formed with a projection  120   a.    
     A pair of coil springs  42  and  44  extend under tension between the drive base  32  and the load plate  34 . In the unloaded condition shown in FIGS. 4 to  7  where the cartridge  14  is partially inserted in the magneto-optical disk drive  10 , the load plate  34  is kept in the upward moved position as viewed in FIG. 5, and the second load cam  124  is engaged with the pin  50  fixed to the base  32 . Accordingly, the coil springs  42  and  44  are in the expanded condition, and the downward movement of the load plate  34  as viewed in FIG. 5 is prevented by the engagement of the second load cam  124  and the pin  50 . 
     Since the load plate  34  is kept in the position moved in the direction P as shown in FIG. 6, the pins  54  of the cartridge holder  52  are located in the horizontal portions of the slots  48  of the lift guides  46 , and the magneto-optical disk  24  is not yet chucked by the spindle motor  108 , but is spaced therefrom. When the cartridge  14  is further inserted into the magneto-optical disk drive  10  from the above unloaded condition, the cartridge  14  comes into abutment against the projection  120   a  of the first load cam  120  to rotate the first load cam  120  counterclockwise as viewed in FIG. 5 against the biasing force of the torsion spring  122 . As a result, the second load cam  124  is disengaged from the pin  50 , and the load plate  34  is moved downward as viewed in FIG. 5 by the biasing forces of the coil springs  42  and  44 . 
     FIGS. 20 and 21 show a condition where the cartridge  14  is fully inserted in the magneto-optical disk drive  10 . In concert with the above movement of the load plate  34 , the pins  54  of the cartridge holder  52  are moved within the slots  48  of the lift guides  46  from the horizontal portions to the upper ends of the inclined portions as viewed in FIG.  21 . Accordingly, the cartridge  14  is moved toward the spindle motor  108 , and the magneto-optical disk  24  of the cartridge  14  is chucked by the spindle motor  108 . In this loaded condition, the load plate  34  is kept in the downward moved position as viewed in FIG. 20 by the biasing forces of the coil springs  42  and  44 , in which the coil springs  42  and  44  are in the contracted condition. In this condition, the spindle motor  108  is driven to rotate the magneto-optical disk  24  and perform reading/writing of data from/to the magneto-optical disk  24 . 
     In ejecting the cartridge  14  out of the magneto-optical disk drive  10 , the eject button  13  is depressed by an operator. As a result, the eject motor  114  is driven to make the cam  116  abut against the engaging member  118  of the load plate  34 , thereby moving the load plate  34  in the direction P shown in FIG.  6 . That is, the load plate  34  is moved upward as viewed in FIG.  20 . Accordingly, the abutment of the second load cam  124  against the pin  50  is released, and the first load cam  120  is rotated clockwise as viewed in FIG. 20 by the biasing force of the torsion spring  122 , thereby ejecting the cartridge  14  out of the magneto-optical disk drive  10 . 
     The cartridge  14  is further ejected by the biasing forces of the torsion springs  66  and  68  mounted on the cartridge holder  52  until the position shown in FIGS. 4 to  7  is reached. The engagement of the spindle motor  108  and the magneto-optical disk  24  is released during the movement of the load plate  34  in the direction P shown in FIG.  6 . 
     In the above ejecting operation, the flat surfaces  87  of the projecting portions  86 a of the first, second, and third cartridge holding assemblies  80 ,  82 , and  84  mounted on the cartridge holder  52  are in elastic contact with the cartridge  14 . That is, a moderate frictional force is generated between the cartridge  14  and the flat surfaces  87  of the projecting portions  86   a  under the spring elasticity of the coil springs  90 . Accordingly, the cartridge  14  can be stably ejected as being braked by this frictional force. Furthermore, since the flat surfaces  87  of the projecting portions  86   a  of the cartridge holding members  86  come into contact with the cartridge  14 , it is possible to effectively prevent scratches on the cartridge shell  16 . 
     In ejecting the cartridge  14 , the second load cam  124  comes into engagement with the pin  50 , thereby preventing the downward movement of the load plate  34  as viewed in FIG.  5 . In this condition, the pins  54  of the cartridge holder  52  are located in the horizontal portions of the slots  48  of the lift guides  46  as shown in FIG.  6 . 
     Having thus described some specific preferred embodiments of the present invention applied to a magneto-optical disk drive, the present invention is not limited to the above preferred embodiments, but similarly applicable to any other optical disk drives in which optical disks are selectively loaded to a spindle motor. Further, the present invention is similarly applicable to any other recording devices in which recording media are accommodated in a cartridge shell and the recording media are selectively loaded to a spindle motor. 
     According to the present invention as described above, the cartridge is held by the flat surfaces of the cartridge holding members, thereby effectively preventing the cartridge from being scratched in inserting or ejecting the cartridge. Further, a stable desired frictional force can be obtained in ejecting the cartridge, thereby improving the stability of ejection of the cartridge. Further, the position of engagement between the sliders and the torsion springs is optimized to prevent an increase in sliding load on the sliders, thereby allowing stable insertion and ejection of the cartridge.