PATENT DOCUMENT

Abstract:
A flexible disk drive has the configuration of a type-2 card for use in a personal computer or other information processing apparatus. The flexible disk drive includes a cabinet for insertion into a card slot in the information processing apparatus, a mechanism for inserting and ejecting a recording medium cartridge containing a recording medium, a head for accessing the recording medium, a head drive actuator for moving the head, a recording medium drive actuator for driving the recording medium, a position device for positioning the recording medium in a predetermined position, and a drive force transfer mechanism for transferring the driving force of the recording medium drive actuator to the recording medium. The components of the flexible disk drive have thin profiles to achieve the form factor of the type-2 card.

Full Description:
BACKGROUND OF INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to an exchangeable storage apparatus with exchangeable recording medium to be used for computers, personal computers, and portable information terminals, and so on. More particularly, this invention relates to a Flexible Disk Drive, a recording medium drive actuator, a head drive actuator, and a recording medium cartridge to be used for the flexible disk drive.  
           [0003]    2. Description of the Related Arts  
           [0004]    [0004]FIG. 80 is part of a cross sectional view showing, for instance, a conventional flexible disk drive (hereinafter referred to as the FDD) disclosed in the Japan Patent Examination Hei 06-119699, of a storage for which a recording medium is exchangeable. Especially, the example given in the figure shows a 3.5-inch FDD wherein a recording medium is housed in a so called recording medium cartridge which is consisting of a hard case with a shutter. Also, FIG. 81 is a cross sectional view of the FDD, and FIG. 82 is a top view of FIG. 81. FIGS. 81 and 82 show the relationship between the recording medium cartridge and a positioning means for positioning the recording medium cartridge.  
           [0005]    In the figures, an FDD body  1 , a read/write head  2 , a carriage  3  supporting read/write head  2 , and a head arm  4  are shown. A head drive actuator  5  that drives read/write head  2  by driving carriage  3  is provided with a step motor  6 , a lead screw  7 , a needle  8 , and a guide rod (not shown). This needle  8  is engaged with lead screw  7 . A frame  10 , a mounting part  11  that mounts an external special slot  80 , a guide groove  12 , and a cover (shield)  13  are also shown. A circuit board  14 , a cartridge holder  15 , a cam follower  16 , a shutter opener  17  are shown. Cartridge holder  15  gets engaged with cam follower  16  and shutter opener  17 , and so on. A slide cam part  20  is made up of a cam groove  21  and an eject button  22  and engaged with an eject lever  23 .  
           [0006]    A recording medium cartridge  30  is constructed by a recording medium  31  and a cartridge case  32  having an upper shell  32   a  and a lower shell  32   b . Recording medium  31  is supported by a hub  33 , and cartridge case  32  is provided with a shutter  34 , a window  35 , and recording medium  31 . The cartridge case  32  has a protect hole  32   c  so that information would not be erased once it is written. Also in cartridge case  32 , a resin slide part material  36  is installed to make write protect when write-protect hole  32   c  is in open state and to write information in closed state.  
           [0007]    A recording medium drive actuator  40  rotates recording medium  31 , and composed of a circuit board  14 , a stator  41 , rotor  42 , a drive pin  43 , a chucking magnet  44 , a housing  45 , bearing  46 , a stator yoke  47 , and a spindle shaft  48 . On one part of circumference of rotor  42 , an index magnet  39   a  is attached to detect the position of rotating recording medium  31  as the index signal. An index sensor  39   b  is installed on circuit board  14  to detect the index signal on the position opposite to index magnet  39   a . A disk-in switch  37  to detect that recording medium  31  has been set to read/write position and write protect switch  38  to detect write protect in recording medium  31  are secured as well. For index sensor  39   b , normally hole elements and so on are used, and is often mounted on a case (not shown) in which the position of the index sensor can be mechanically adjusted.  
           [0008]    For write-protect switch  38 , a so-called push switch is often used. When information can be written, switch end  38   a  of write-protect switch  38  is pushed downward by slide part material  36 . Conversely, when data write is inhibited, switch end  38   a  is in free state and placed higher than when it is pushed down.  
           [0009]    Most disk-in switch  37  and write protect switch  38  are of the same shape or uniform shape. When recording medium cartridge  30  is set to read/write position, in the so-called load state, end  37   a  of disk-in switch  37  is pushed down by lower shell  32   b  of cartridge case  32  or by slide part material  36  which opens or closes write-protect hole  32   c . When recording medium  31  is in read/write disabled state, on the other hand, in the so-called unload state, switch end  37   a  is lifted up.  
           [0010]    The relationship between stator  41  and rotor  42  is the so-called outer rotor type and stator  41  is positioned in the center and rotor  42  is positioned around it. An interface connector  70 , an external special slot  80 , a mounting screw  81 , an external cable  82 , an external connector  83  are also shown. Generally, FDD body  1  is secured with mounting screw  81  and so on, for instance, on special slot  80  of a personal computer or an information processing terminal, and so on. Interface connecter  70  is engaged with a connecter  83  connected with a flexible cable  82  from the external part.  
           [0011]    Now, operation is explained with figures.  
           [0012]    An explanation is given concerning the state transition from the so-called unload state in which data read or write on recording medium  31  is disabled, to the load status in which data read and write is enabled.  
           [0013]    When recording medium cartridge  30  is inserted into FDD body  1 , it is held by cartridge holder  15  and lifted up by cam groove  21  and cam follower  16  of slide cam part  20 . Thus, it is inserted at the height higher than spindle shaft  48  in the center of recording medium drive actuator  40 . Next, when the center of recording medium cartridge  30  has come near spindle shaft  48 , shutter  34  is opened by shutter opener  17 . Further, eject lever  23  is rotated. The latch of slide cam part  20  is released. And cartridge holder  15  is lowered by cam groove  21 . At the same time, since head arm  4  having read/write head  2  is pressed on the frame side touching cartridge holder  15 , the head arm  4  rotates. When recording medium cartridge  30  is lowered to a certain position, two holes  33   a  and  33   b  made in hub  33  which is part of recording medium  31 , get engaged with spindle shaft  48  and drive pin  43 , thereby positioning of recording medium  31  is performed. The hole  33   a  that engages with spindle shaft  48  is square, and hole  33   b  that engages with drive pin  43  is partly extended in the radius direction, eccentricity works in the radius direction shown in the arrow H by the rotation of drive pin  43  to hub  33 , thereby eliminating backlash that generates in hole  33   a  which engages with spindle shaft  48 . Also, the hub  33  is made of magnetic material. It is sucked and retained (chucked) by chucking magnet  44 . The chucking magnet  44  is a means for transferring recording medium drive force, provided with the recording medium drive actuator  40 . After that, carriage  3  holding read/write head  2  is driven by head drive actuator  5 . When read/write head  2  is moved to the recording surface of recording medium  31 , reading or writing data on recording medium  31  is made possible, thereupon completing load state.  
           [0014]    Then, the operation of load state to unload state of recording medium cartridge  30  is explained next.  
           [0015]    By pushing eject button  22  down to the predetermined position, cartridge holder  15  lifts up along cam groove  21 . On its way upward, when cartridge holder  15  touches and rotates head arm  4 , upper and lower read/write head  2  separate from recording medium  31 . Together with lifted cartridge holder  15 , when recording medium cartridge  30  reaches the position at which it can jump over spindle shaft  48 , shutter  34  gets disengaged from shutter opener  17 . As shutter  34  is closed, cartridge holder  15  is ejected by shutter opener  17 . Cartridge holder  15  is kept from lowering by slide cam part  20  and the latch of eject lever  23 . As head arm  4  maintains the open state of both read/write heads  2 , unload state has made complete.  
           [0016]    [0016]FIG. 83 is a cross sectional view showing inside of a conventional head drive actuator  5  of FIG. 80. A step motor  6  in the figure is referred to as the so-called claw-pole type motor. It is constructed with a radially magnetized cylindrical rotor  61 , and a claw-pole stator  65  is positioned on the outer circumference of this cylindrical rotor  61 , and circular stator coil  66  is wound around further on the outer circumference. To output torque necessary to drive carriage  3  with step motor  6  in such construction, the thickness of step motor  6  must be about 10.0 mm.  
           [0017]    [0017]FIG. 84 shows another example of related art. It shows exchangeable storage like IC memory card and so on, disclosed in, for instance, Japan Patent Examination HEI 5-181565.  
           [0018]    In the figure, an IC memory card  1   a , a magnetic disk storage  1   b , a slot guide  11   b,  an interface connector  70   a  of IC memory card  1   a , an interface connector  70   b  of magnetic disk storage  1   b , an IC memory card slot  80   a , and a portable information terminal  85   a  for a personal computer and so on, are shown. Generally, this type of IC memory cards is also called the PC card, and its standard is set by the Personal Computer Memory Card Association (PCMCIA), an organization for extended IC card standardization in the United States. The width of the card by the PCMCIA is uniformly 54.0 mm. For thickness, there are the following sizes:  
           [0019]    Type-1: 3.3 mm thick  
           [0020]    Type-2: 5.0 mm thick  
           [0021]    Type-3: 10.5 mm thick  
           [0022]    IC memory card  1   a  is currently used for general purpose for portable information terminal  85   a . For interface connector  70   a , the standard corresponding to the type-2 with thickness 5.0 mm is used.  
         Problems to be Solved by the Invention  
         [0023]    Recently, as the exchangeable storage to be used for portable information terminal  85   a , IC memory card  1   a  is often used as it is compact and convenient to carry with. However, IC memory card  1   a  has the following problems.  
           [0024]    (1) The recording medium in the IC memory card is the IC memory. Because the IC memory itself cannot be replaced, the IC memory card itself must be replaced.  
           [0025]    (2) Because the IC memory is expensive at present, the price of IC memory card is also high.  
           [0026]    (3) Due to the reasons stated above (1) and (2), using an IC memory card for the replacement of a recording medium results in high cost.  
           [0027]    Because of this, there is a movement toward using FDDs, with its low-priced recording medium cartridge  30  and easy replacement of the recording medium, instead of the IC memory cards by making FDDs smaller and thinner. However, FDDs must be matched to the type-2 standard size (5.0 mm in thickness and 54.0 mm in width) of the PCMCIA standard, and be manufactured according to the size of the slots to which IC memory card  1   a  of the PCMCIA type-2 standard is to be inserted. The following problems must be tackled.  
           [0028]    (1) When inserting recording medium cartridge  30  into the FDD, shutter  34  is opened in the direction of Y by shutter opener  17  as the cartridge  30  is inserted in the direction of arrow X as shown in FIG. 82. At this time, a head arm  4  must move up and down significantly because read/write head  2  jumps over the part shown as S in the figure. It is therefore difficult to make FDDs thinner, as the device thickness of FDD must at least include recording medium cartridge  30 , read/write head  2 , head arm  4 , and carriage  3 .  
           [0029]    (2) Due to the chucking mechanism of recording medium (disk)  31 , in which hub  33  engages with spindle shaft  48  and drive pin  43 , recording medium cartridge  30  must be moved up and down more than the engagement length of hub  33  and spindle shaft  48  or drive pin  43  for loading and unloading recording medium cartridge  30 . This thickness enabling this perpendicular movement must be secured in FDD. Because total thickness of spindle shaft  48  and recording medium cartridge  30  must at least be secured, the thinning of FDD is difficult.  
           [0030]    (3) In order to thin the FDD under the current structure of head drive actuator  5 , the turns of stator coil  66  should be reduced. However, it is difficult to obtain torque necessary for driving carriage  3 .  
           [0031]    (4) In order to thin the FDD under the current structure of recording medium drive actuator  40 , the turns of stator  41  should be reduced. However, it is difficult to obtain torque necessary for driving recording medium  31 .  
           [0032]    (5) It was difficult to thin conventional FDDs and recording medium cartridges because the height as the storage and the height as the recording medium cartridge were required so that ends  37   a  and  38   a  of disk-in switch  37  and write-protect switch  38  can move up and down.  
           [0033]    (6) In addition, because index sensor  39   b  is made of hole elements, a certain area was required. Rotor  42  must have an area on which to mount opposing index magnet  39   a , making the device compact difficult. And index sensor  39   b  that detect the mechanical position of recording medium  31  must be assembled and adjusted so that the position of recording magnet  31  and the positions of index magnet  39   a  and index sensor  39   b  agree when recording medium  31  is mounted on rotor  42  by chucking magnet  44 , and so on.  
           [0034]    Accordingly, it is a primary object of this invention to overcome problems associated with making the FDD for which recording media can be exchanged smaller and thinner, and to achieve the FDD by which the IC memory card can be substituted. Furthermore, it is another object of this invention to achieve the recording medium drive actuator, head drive actuator, and recording medium cartridge to be used for the thinned FDD.  
         SUMMARY OF THE INVENTION  
         [0035]    According to one aspect of this invention, An exchangeable storage apparatus comprising: a cabinet to be inserted into and retained by a card slot provided for an information processing apparatus;  
           [0036]    an inserting and ejecting means for freely inserting or ejecting a recording medium cartridge containing a recording medium into or from the cabinet;  
           [0037]    a head built in the cabinet for making an access to the recording medium;  
           [0038]    a head drive actuator built in the cabinet for moving the head and determining a position of the head;  
           [0039]    a recording medium drive actuator built in the cabinet for driving the recording medium;  
           [0040]    a positioning means built in the cabinet for positioning the recording medium being inserted to the predetermined position;  
           [0041]    a driving force transfer means built in the cabinet for transferring a driving force of the recording medium drive actuator to the recording medium; and  
           [0042]    an information transmission means provided for the cabinet for transmitting information between the information processor and the recording medium.  
           [0043]    According to another aspect of this invention, An exchangeable storage apparatus comprising:  
           [0044]    a head which reads and writes data on the recording medium having a driven part for rotation and storing information;  
           [0045]    a head drive actuator that moves the head and determines a position of the head;  
           [0046]    a recording medium drive actuator that drives the recording medium;  
           [0047]    a driving force transfer means for transferring the driving force of the recording medium drive actuator to the driven part of the recording medium;  
           [0048]    a positioning means for positioning the recording medium to a predetermined position; and  
           [0049]    a head unload means for unloading the head toward the direction of the recording medium drive actuator while the recording medium is not being inserted.  
           [0050]    According to another aspect of this invention, An exchangeable storage apparatus comprising:  
           [0051]    a head which reads and writes data on the rotating recording medium having a driven part for rotation and storing information;  
           [0052]    a head drive actuator which moves the head and determines a position of the head;  
           [0053]    a positioning means for positioning the recording medium being inserted to a predetermined position;  
           [0054]    a recording medium drive actuator having a stator formed by installing a block inside a stator core, wherein the block is made up of a plurality of center cores equivalent to the number of drive phases and by inserting a cylindrical coil bobbin wound with a coil into the center core, and a rotor provided inside the stator and drives the recording medium; and  
           [0055]    a driving force transfer means for transferring the driving force of the recording medium drive actuator to the driven part of the recording medium.  
           [0056]    According to another aspect of this invention, An exchangeable storage apparatus comprising:  
           [0057]    a head that reads and writes data on a recording medium having a driven part for rotation and storing information;  
           [0058]    a recording medium drive actuator that drives the recording medium;  
           [0059]    a positioning means for positioning the recording medium being inserted to a predetermined position;  
           [0060]    a driving force transfer means for transferring a driving force of the recording medium drive actuator to the driven part of the recording medium; and  
           [0061]    a head drive actuator including a rotor having a cylindrical rotation part and giving the driving force to the head, and a stator installed at opposite sides of an outer circumference of the cylindrical rotation part of the rotor and having a coil wound cylindrically along an elongated direction of the rotor.  
           [0062]    According to another aspect of this invention, An exchangeable storage apparatus comprising:  
           [0063]    a head that reads and writes data on a recording medium having a driven part and storing information, and wherein an unload amount of the head when the recording medium is inserted and ejected is within a thickness of a recording medium cartridge holding the recording medium;  
           [0064]    a head drive actuator which moves the head and determines a position of the head;  
           [0065]    a recording medium drive actuator which drives the recording medium;  
           [0066]    a positioning means for positioning the recording medium being inserted to a predetermined position; and  
           [0067]    a driving force transfer means for transferring a driving force of the recording medium drive actuator to the driven part of the recording medium.  
           [0068]    According to another aspect of this invention, An exchangeable storage apparatus comprising:  
           [0069]    a head that reads and writes data on a recording medium having a positioning part for positioning and having a driven part for rotation and storing information, and wherein an unload amount of the head when the recording medium is inserted and removed is within a thickness of a recording medium cartridge holding the recording medium;  
           [0070]    a head drive actuator including a rotor having a cylindrical rotation part and giving the driving force to the head, and a stator installed at opposite sides of an outer circumference of the cylindrical rotation part of the rotor and having a coil wound cylindrically along the elongated direction of the rotor;  
           [0071]    a recording medium drive actuator including a stator having a stator core and a block inside the stator core, the block having a plurality of center cores equivalent to the number of drive phases, and a cylindrical coil bobbin wound with a coil inserted into the center core, and a rotor installed inside the stator to drive the recording medium;  
           [0072]    a head unload means for unloading the head toward the direction of the recording medium drive actuator while the recording medium is not being inserted;  
           [0073]    a positioning means which is retractably projected to the recording medium being inserted for positioning the recording medium to a predetermined position by engaging with the positioning part of the recording medium; and  
           [0074]    a driving force transfer means for transferring a driving force of the recording medium drive actuator to the driven part of the recording medium.  
           [0075]    According to another aspect of this invention, An exchangeable storage apparatus comprising:  
           [0076]    a head that reads and writes data on a recording medium having a positioning part for positioning and having a driven part for rotation and storing information;  
           [0077]    a head drive actuator that moves the head and determines the position of the head;  
           [0078]    a recording medium drive actuator to drive the recording medium;  
           [0079]    a driving force transfer means for transferring a driving force of the recording medium drive actuator to the driven part of the recording medium;  
           [0080]    a first frame that supports the head drive actuator and the recording medium drive actuator;  
           [0081]    a retaining means for holding the recording medium inserted from outside; a second frame that supports the retaining means;  
           [0082]    a frame rotation part which supports an end of the first frame and an end of the second frame for free rotation and makes the second frame further rotate so as to open the second frame against the first frame;  
           [0083]    a head unload means for unloading the head toward the opening direction of the second frame opened against the first frame with the frame rotation part; and  
           [0084]    a positioning means provided for the first frame for positioning the recording medium inserted to the retaining means to a predetermined position by engaging with the positioning part of the recording medium when the first frame and the second frame are closed.  
           [0085]    According to another aspect of this invention, A recording medium drive actuator comprising: a stator having a stator core and a block inside the stator core, the block having a plurality of center cores equivalent to the number of driving phases and a cylindrical coil bobbin wound with a coil inserted into the center core; and  
           [0086]    a rotor installed inside the stator to drive the recording medium.  
           [0087]    According to another aspect of this invention, A head drive actuator comprising:  
           [0088]    a rotor having a cylindrical rotation part and that giving a driving force to a head; and  
           [0089]    a stator installed at opposite sides to an outer circumference of the cylindrical rotation part of the rotor and cylindrically wound with a coil in the elongated direction of the rotor.  
           [0090]    According to another aspect of this invention, A recording medium cartridge comprising:  
           [0091]    a disk-shaped recording medium;  
           [0092]    a case housing the recording medium;  
           [0093]    a window for exposing a part of the recording medium from the case;  
           [0094]    a shutter provided for the case for closing and exposing the window;  
           [0095]    a latch movable in the direction perpendicular to the closing and opening direction of the shutter; and  
           [0096]    a band that links the shutter with the latch.  
           [0097]    According to another aspect of this invention, A recording medium cartridge comprising: a lower shell and an upper shell;  
           [0098]    two conductive metal plates exposed on the surface of one of the lower shell and the upper shell; and  
           [0099]    the slide member for switching connection of two conductive metal plates.  
           [0100]    According to another aspect of this invention, A recording medium cartridge comprising: a disk recording medium; a case for storing the recording medium; means for detecting a fixed position of the recording medium in one rotation, the means for detecting a fixed position being provided in the case.  
           [0101]    According to another aspect of this invention, A recording medium cartridge comprising:  
           [0102]    a disk recording medium;  
           [0103]    a lower shell and an upper shell for storing the recording medium; and  
           [0104]    a notch formed at part of the circumference of the recording medium.  
           [0105]    According to another aspect of this invention, A method for using a card type recording medium slot of an information processor comprising steps of:  
           [0106]    (a) mounting a storage apparatus, which is able to exchange a recording medium, on the card type recording medium slot under a condition that the storage apparatus can be easily dismount;  
           [0107]    (b) inserting the recording medium and setting the position to the storage apparatus;  
           [0108]    (c) accessing the recording medium, whose position is set, using a card recording medium interface mounted on the card type recording medium slot.  
           [0109]    Other objects features, and advantages of the invention will be apparent from the following description when taken in conjunction with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0110]    The invention will be further described by way of non-limitative example with reference to the accompanying drawings, in which:  
         [0111]    [0111]FIG. 1 shows the whole configuration of the FDD, the recording medium cartridge to be inserted into the FDD, and a slot installed on portable information terminal, and so on, to insert the FDD, in accordance with Embodiment 1 of the present invention;  
         [0112]    [0112]FIG. 2 is a cross sectional view showing part of the FDD according to Embodiment 1 of the present invention;  
         [0113]    [0113]FIG. 3 is a cross sectional view showing part of the head drive actuator for determining the moving position of the head according to Embodiment 1 of this invention;  
         [0114]    [0114]FIG. 4A and FIG. 4B give a top view and a side view of the recording medium cartridge according to Embodiment 1 of this invention;  
         [0115]    [0115]FIG. 5 is a plain cross sectional view showing the recording medium drive actuator according to Embodiment 1 of this invention;  
         [0116]    [0116]FIG. 6 is a cross sectional view showing the FDD in accordance with Embodiment 1 of this invention;  
         [0117]    [0117]FIG. 7 is a cross sectional view showing the FDD in accordance with Embodiment 2 of this invention;  
         [0118]    [0118]FIGS. 8A, 8B, and  8 C are cross sectional views showing the FDD in accordance with Embodiment 3 of this invention;  
         [0119]    [0119]FIGS. 9A, 9B, and  9 C are a cross sectional view of the FDD, and top views of the hub and spindle part in accordance with Embodiment 4 of this invention;  
         [0120]    [0120]FIGS. 10A and 10B are magnified views of positioning means and driving force transfer means of the FDD;  
         [0121]    [0121]FIG. 11 is a cross sectional view showing the FDD in accordance with Embodiment 5 of this invention;  
         [0122]    [0122]FIG. 12 is a cross sectional view showing the FDD before a recording medium is inserted in accordance with Embodiment 6 of this invention;  
         [0123]    [0123]FIG. 13 is a cross sectional view showing the FDD after a recording medium is inserted in accordance with Embodiment 6 of this invention;  
         [0124]    [0124]FIG. 14 is a cross sectional view showing the FDD before a recording medium is inserted and when the head is positioned on the inner circumference of the recording medium in accordance with Embodiment 7 of this invention;  
         [0125]    [0125]FIG. 15 is a cross sectional view showing the FDD before a recording medium is inserted and when the head is positioned on the outer circumference of the recording medium in accordance with Embodiment 7 of this invention;  
         [0126]    [0126]FIG. 16 is a cross sectional view showing the FDD after a recording medium is inserted in accordance with Embodiment 7 of this invention;  
         [0127]    [0127]FIG. 17 is a cross sectional view showing the FDD before a recording medium is inserted and the head is positioned on the inner circumference of the recording medium in accordance with Embodiment 8 of the invention;  
         [0128]    [0128]FIG. 18 is a cross sectional view showing the FDD before a recording medium is inserted and the head is positioned on the outer circumference of the recording medium in accordance with Embodiment 8 of this invention;  
         [0129]    [0129]FIG. 19 is a cross sectional view showing the FDD after a recording medium is inserted in accordance with Embodiment 8 of this invention;  
         [0130]    [0130]FIGS. 20A and 20B are a top view and a cross sectional view showing the construction of recording medium drive actuator in accordance with Embodiment 9 of this invention;  
         [0131]    [0131]FIG. 21 explains the construction of the stator element in accordance with Embodiment 9 of this invention;  
         [0132]    [0132]FIG. 22 explains the construction of the stator element in accordance with Embodiment 10 of this invention;  
         [0133]    [0133]FIG. 23 explains another example of the stator element construction in accordance with Embodiment 10 of this invention;  
         [0134]    [0134]FIG. 24 is a cross sectional view showing the construction of recording medium drive actuator in accordance with Embodiment 11 of this invention;  
         [0135]    [0135]FIG. 25 is a cross sectional view showing the construction of recording medium drive actuator in accordance with Embodiment 12 of this invention;  
         [0136]    [0136]FIG. 26 shows a cross sectional view showing part of the construction of head drive actuator in accordance with Embodiment 13 of this invention;  
         [0137]    [0137]FIG. 27 is a top view showing the construction of head drive actuator in accordance with Embodiment 13 of this invention;  
         [0138]    [0138]FIG. 28 shows a side sectional view in A-A direction indicated in the top view of head drive actuator of FIG. 27 in accordance with Embodiment 13 of this invention;  
         [0139]    [0139]FIG. 29 shows a side sectional view in B-B direction indicated in the top view of head drive actuator of FIG. 27 in accordance with Embodiment 13 of this invention;  
         [0140]    [0140]FIG. 30 shows a side sectional view in C-C direction indicated in the top view of head drive actuator of FIG. 27 in accordance with Embodiment 13 of this invention;  
         [0141]    [0141]FIG. 31 shows a side sectional view in D-D direction indicated in the tope view of head drive actuator in FIG. 27 in accordance with Embodiment 13 of this invention;  
         [0142]    [0142]FIG. 32 shows a top view showing the construction of head drive actuator in accordance with Embodiment 14 of this invention;  
         [0143]    [0143]FIG. 33 shows a side sectional view in E-E direction indicated in the top view of head drive actuator of FIG. 32 in accordance with Embodiment 14 of this invention;  
         [0144]    [0144]FIG. 34 is a side sectional view in F-F direction indicated in the top view of head drive actuator of FIG. 32 in accordance with Embodiment 14 of this invention;  
         [0145]    [0145]FIG. 35 is a side sectional view in G-G direction indicated in the top view of head drive actuator of FIG. 32 in accordance with Embodiment 14 of this invention;  
         [0146]    [0146]FIG. 36 is a side sectional view in H-H direction indicated in the tope view of head drive actuator of FIG. 32 according to Embodiment 14 of this invention;  
         [0147]    [0147]FIGS. 37A and 37B show the top view and side view of the recording medium cartridge when the shutter is closed according to Embodiment 15 of this invention;  
         [0148]    [0148]FIGS. 38A and 38B show the top view and side view of the recording medium cartridge when the shutter is opened according to Embodiment 15 of this invention;  
         [0149]    [0149]FIG. 39 shows an FDD according to embodiment 16 of this invention;  
         [0150]    [0150]FIG. 40 shows an inner structure of the FDD according to embodiment 16 of this invention;  
         [0151]    [0151]FIG. 41 shows a perspective view of the FDD according to embodiment 16 of this invention;  
         [0152]    [0152]FIG. 42 shows a side cross sectional view of the FDD according to embodiment 16 of this invention;  
         [0153]    [0153]FIG. 43 shows a perspective view seen from the direction of the top face of the storage around a read/write head according to embodiment 16 of this invention;  
         [0154]    [0154]FIG. 44 shows a cross sectional side view of an outskirts of the read/write head according to embodiment 16 of this invention;  
         [0155]    [0155]FIG. 45 shows a cross sectional side view of the outskirts of the read/write head according to embodiment 16 of this invention;  
         [0156]    [0156]FIG. 46 shows a perspective view of the outskirts of the read/write head and a head unload mechanism according to embodiment 16 of this invention;  
         [0157]    [0157]FIG. 47 shows a perspective view of the read/write head and the head unload mechanism according to embodiment 16 of this invention;  
         [0158]    [0158]FIG. 48 shows an external perspective view of an eject shaft according to embodiment 16 of this invention;  
         [0159]    [0159]FIG. 49 shows a perspective view of the outskirts of the eject coil spring of the frame side wall part according to embodiment 16 of this invention;.  
         [0160]    [0160]FIG. 50 shows a perspective view of the shaft barb stopper piece which controls the movement of the eject coil spring of the frame side wall part according to embodiment 16 of this invention;  
         [0161]    [0161]FIG. 51 shows a perspective view of the head unload mechanism under the unload state according to embodiment 16 of this invention;  
         [0162]    [0162]FIG. 52 shows a perspective view of the head unload mechanism under the load state according to embodiment 16 of this invention;  
         [0163]    [0163]FIG. 53 shows a part of a cross sectional side view of a rotating force receiver and the outskirt of it according to embodiment 17 of this invention;  
         [0164]    [0164]FIG. 54 shows a perspective view of the mechanism of setting position of the recording medium cartridge under the unload state of the storage according to embodiment 18 of this invention;  
         [0165]    [0165]FIG. 55 shows a perspective view of the mechanism of setting the position of the recording medium cartridge under the load state of the storage according to embodiment 18 of this invention;  
         [0166]    [0166]FIG. 56 shows a perspective view of the mechanism of setting the position of the recording medium cartridge under the load state of the storage according to embodiment 18 of this invention;  
         [0167]    [0167]FIG. 57 shows a perspective view of the structure of the mechanism of setting the position of the recording medium cartridge according to embodiment 19 of this invention;  
         [0168]    [0168]FIG. 58 shows a part of cross sectional view under the condition that the recording medium cartridge according to embodiment 20 of this invention is inserted to the storage;  
         [0169]    [0169]FIG. 59 shows a perspective view of the upper cover according to embodiment 20 of this invention;  
         [0170]    [0170]FIG. 60 shows a plan view of the recording medium cartridge according to embodiment 21 of this invention;  
         [0171]    [0171]FIG. 61 shows a side view of the recording medium cartridge according to embodiment 21 of this invention;  
         [0172]    [0172]FIG. 62 shows a cross sectional plan view of the recording medium cartridge according to embodiment 21 of this invention;  
         [0173]    [0173]FIG. 63 shows a side cross sectional view seen from A-A direction of FIG. 62 according to embodiment 21 of this invention;  
         [0174]    [0174]FIG. 64 shows a part of plan view of the FDD according to embodiment 21 of this invention;  
         [0175]    [0175]FIG. 65 shows a side cross sectional view seen from B-B direction of FIG. 64 according to embodiment 21 of this invention and a view of the recording medium cartridge and the switching storage under the condition that the recording medium cartridge is mounted in the storage;  
         [0176]    [0176]FIG. 66 shows a part of cross sectional plan view of the recording medium cartridge according to embodiment 21 of this invention;  
         [0177]    [0177]FIG. 67 shows a part of cross sectional side view of the recording medium cartridge according to embodiment 21 of this invention;  
         [0178]    [0178]FIG. 68 shows a plan view of the recording medium cartridge and the FDD under the condition that the recording medium cartridge according to embodiment 22 of this invention is mounted in the storage;  
         [0179]    [0179]FIG. 69 shows a side view of FIG. 68 according to embodiment 22 of this invention and a part of cross sectional side view seen from C-C direction in FIG. 68;  
         [0180]    [0180]FIG. 70 shows a cross sectional plan view of the recording medium cartridge and the FDD under the condition that the recording medium cartridge according to embodiment 23 of this invention is mounted on the storage;  
         [0181]    [0181]FIG. 71 shows a part of cross sectional side view seen from D-D direction of FIG. 70 according to embodiment 23 of this invention;  
         [0182]    [0182]FIG. 72 shows a cross sectional plan view of the recording medium cartridge and the FDD under the condition that the recording medium cartridge according to embodiment 24 of this invention is mounted on the storage;  
         [0183]    [0183]FIG. 73 shows a part of cross sectional side view seen from E-E direction of FIG. 72 according to embodiment 24 of this invention;  
         [0184]    [0184]FIG. 74 shows a plan view under the condition that a shutter of the recording medium cartridge according to embodiment 25 of this invention is opened;  
         [0185]    [0185]FIG. 75 shows a side face cross sectional view seen from F-F direction of FIG. 74 according to embodiment 25 of this invention;  
         [0186]    [0186]FIG. 76 shows a side face cross sectional view seen from F-F direction of FIG. 74 in the recording medium cartridge according to embodiment 26 of this invention;  
         [0187]    [0187]FIG. 77 shows a plan view under the condition that the shutter of the recording medium cartridge according to embodiment 27 of this invention is opened;  
         [0188]    [0188]FIG. 78 shows a plan cross sectional view of the recording medium cartridge and the FDD under the condition that the recording medium cartridge according to embodiment 27 of this invention is mounted in the storage;  
         [0189]    [0189]FIG. 79 shows a part of cross sectional side view seen from G-G direction of FIG. 78 according to embodiment 27 of this invention;  
         [0190]    [0190]FIG. 80 is a slanted cross sectional view showing part of the conventional FDD; FIG. 81 is a cross sectional view showing the conventional FDD;  
         [0191]    [0191]FIG. 82 gives a top view of the conventional recording medium cartridge;  
         [0192]    [0192]FIG. 83 is a slanted cross sectional view showing part of the conventional head drive actuator; and,  
         [0193]    [0193]FIG. 84 shows the construction of the conventional IC memory card and personal computer.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     Embodiment 1  
       [0194]    Hereinafter, an embodiment of this invention is explained with reference to figures.  
         [0195]    [0195]FIG. 1 shows the whole configuration of an FDD in accordance with Embodiment 1, a recording medium cartridge to be inserted into the FDD, and a slot with which to install the FDD to, for instance, a portable information terminal, and so on. FIG. 2 is a cross sectional view showing part of the FDD. FIG. 3 shows the inside configuration of a head drive actuator to be mounted on the FDD.  
         [0196]    [0196]FIGS. 4A and 4B show the top view and side view of a recording medium cartridge to be inserted into the FDD. FIG. 5 is the top view showing a recording medium drive actuator that drives a recording medium inside the FDD. FIG. 6 is a cross sectional view showing one side of the FDD in a load status with a recording medium cartridge being inserted in the FDD.  
         [0197]    In the figures, an FDD unit  100 , a read/write head  101 , a carriage  102 , and a head arm  104  are shown. A head drive actuator  105  determines the moving position of read/write head  101 , and is made up of a step motor  106 , a lead screw  107 , a needle  108 , and a guide rod  109 . Needle  108  is engaged with lead screw  107 . A frame  110 , a slot guide  111 , a cover shield  113 , and a circuit board  114  are also shown.  
         [0198]    A recording medium drive actuator  140  is made up of a stator  141 , a teeth  142 , a coil  143 , and a rotor  150 . Rotor  150  is made up of a rotor magnet  151 , a rotor yoke  152 , a chucking magnet  154  which is a driving force transfer means, and a spindle part  155 , a recording medium positioning means. In the center of spindle part  155 , a centering ball  158 , and a ball preload spring  159  which is pressure means are arranged. Bearing  170 , the bearing part, is secured by frame  110  on its secured side cartridge, and its rotating side is supported by rotor yoke  152 . Accordingly, spindle part  155  is supported so as to freely rotate. Spindle part  155  is connected with rotor yoke  152 , for example, by means of a caulk. Further, an insertion and ejection port  180  of recording medium cartridge  300 , an interface connector  181  complying with standard type-2 of the PCMCIA, and reversed-insertion preventive grooves  182  and  183  are shown.  
         [0199]    A slot  200  is general standard type-2 of the PCMCIA, which is provided by, for instance, a portable information terminal, and so on. An eject button  222  of FDD unit  100 , an eject lever  223 , an insertion port  280 , and a connector  283  are shown.  
         [0200]    A recording medium cartridge  300 , a recording medium  301 , a cartridge case  302 , a hub  303 , a shutter  304 , a window  305 , an opener band  306 , an opener latch  307 , and guide rollers  308  and  309  are shown. Although not included in the figure, tension is applied to at least part of opener band  306  to prevent slack in opener band  306 . For instance, opener band  306  is structured as to be pressed toward the outer circumference of cartridge case  302 . Also, both ends of opener band  306  are fixed to shutter  304 . Opener band  306  is bonded with opener latch  307  in its halfway. In FIG. 6, a sensor pad  390 , an index mark  391 , and a taper part  392  attached to hub  303  are shown as well.  
         [0201]    Here, it can be seen that the structure of step motor  106  of head drive actuator  105  of FIG. 3 is made thinner than the conventional structure shown in FIG. 83, by placing the coils on both sides of the rotor.  
         [0202]    The structure of recording medium drive actuator  140  of FIG. 5 is a so-called inner rotor type for which rotor  150  is placed inside stator  141  as opposed to the conventional outer rotor type illustrated in FIG. 81. Further, as is explained later, at least multiple blocks, one block being the polarity having the number of coils equivalent to the number of phases of drive current, are arranged for stator  141 . The turns per coil is reduced and the thinning of recording medium drive actuator  140  is attempted by this structure.  
         [0203]    An operation explanation is given for a transitional state from which FDD unit  100  is not possible to read or write on recording medium  301 , the so-called unload state into the load state in which read and write is made possible.  
         [0204]    For FDD unit  100  of this embodiment, a cover shield  113  is secured to frame  110  which is combined with interface connector  181 . Recording medium cartridge  300  is inserted from insertion and ejection port  180 . That is, when this recording medium cartridge  300  is inserted into FDD unit  100 , recording medium cartridge  300  is inserted as being held at the uniform height toward the insertion direction from insertion and ejection port  180 .  
         [0205]    As recording medium cartridge  300  is inserted, the end of this recording medium cartridge  300  touches centering ball  158  which is retractably located in the center of spindle part  155 . Then, recording medium cartridge  300  pushes down centering ball  158  pressed in the direction of recording medium cartridge  300  by ball preload spring  159 , thereby enabling recording medium cartridge  300  to get further inserted. When centering ball  158  passes over shutter  304 , and before the end of recording medium cartridge  300  reaches the head, the opener lever (not shown) installed on the side wall of insertion and ejection port  180  and opener latch  307  get engaged with so as to slide shutter  304  and to open window  305  to which read/write head  101  makes an access to exposed recording medium  301 . The operation of recording medium cartridge  300  at this time is explained in detail. The exposed states of recording medium  301  are shown in FIG. 4A and FIG. 4B. As shown in FIG. 4A, as recording medium cartridge  300  is getting inserted in the direction X, opener latch  307  moves in the direction of -X by the opener lever (not shown) installed inside the wall of insertion and ejection port  180  of FDD unit  100 . As shutter  304  engaged with opener latch  307  by opener band  306  is pulled to the direction of -Y, window  305  is opened and recording medium  301  is exposed. At this time, any parts or any materials for cartridge case  302  and shutter  304  do not exist in area S shown in the figure. The unload operation of read/write head  101  is saved, thereby making the thickness necessary for FDD unit  100 . The thickness of the FDD unit  100  can be total thickness of read/write head  101 , carriage  102 , head arm  104 , and recording medium  301 . Namely, with respect to the conventional recording medium cartridge, read/write head  101  had to avoid the amount for jumping over the cartridge case or shutter. In this embodiment, however, the avoidance amount is required only for jumping over recording medium  301 .  
         [0206]    When this recording medium cartridge  300  is further inserted, at the position where recording medium cartridge  300  has been completely inserted, e.g., hole  313  of hub  303  comes close to centering ball  158 , this centering ball  158  gets pushed up by ball preload spring  159 . Recording medium  301  is centered and positioned when ball preload spring  159  is engaged with hole  313 . Because the hub  303  is made of magnetic material, the hub  303  is sucked and retained (chucked) by chucking magnet  154  which is a recording medium drive force transfer means. Accordingly, the load state is completed.  
         [0207]    In this way, FDD unit  100  thinner than the conventional type is achieved by configuring head drive actuator  105 , recording medium drive actuator  140 , and recording medium cartridge  300  as explained above. Therefore, FDD unit  100  is not more than 5.0 mm, the thickness by which insertion into slot  200  is permitted for the standard type-2 of the PCMCIA can be obtained. To obtain FDD unit  100  of thickness 5.0 mm or less, it is desirable that the thickness of recording medium drive actuator  140  be made less than about 2.5 mm and the thickness of recording medium cartridge less than about 2.0 mm. Further, to make the width of FDD unit  100  less than 54.0 mm, it is desirable that the width of recording medium cartridge  300  be made less than 48.0 mm and the diameter of recording medium  301  be less than 1.8 inch.  
       Embodiment 2  
       [0208]    In embodiment 1, an example of chucking magnet  154  fixedly secured to spindle part  155  is shown. In this embodiment, an example of chucking magnet  154  that is freely movable within the predetermined distance is indicated.  
         [0209]    [0209]FIG. 7 is a side cross sectional view showing the chucking construction of recording medium cartridge  300  and spindle part  155  of Embodiment 2.  
         [0210]    In the figure, a magnet holder  153  connects chucking magnet  154  with spindle part  155 . Magnet holder  153  is installed on spindle part  155  in such a way that it can move freely in the radial direction up to a predetermined movement distance.  
         [0211]    According to this embodiment, because chucking magnet  154  moves to a right position to be chucked by means of chucking holder  153 , a phenomenon in which chucking magnet  154  sucks and secures hub  303  before centering ball  158  completes the centering of recording medium  301  can be avoided, resulting in more accurate centering. Moreover, always correct centering operation allows chucking magnet  154  to have larger sucking force than the construction of embodiment 1, which further enables recording medium  301  to be held more firmly. Furthermore, energization of centering ball  158  by ball preload spring  159  is reduced, rendering the insertion of recording medium cartridge  300  easier.  
       Embodiment 3  
       [0212]    In this embodiment, other examples of chucking mechanism for the recording medium drive actuator are shown.  
         [0213]    [0213]FIG. 8A is a side cross sectional view showing the chucking structure of recording medium cartridge  300  and spindle part  155   b  of this embodiment. FIG. 8B is a top view of the hub and FIG. 8C is a top view of the spindle part.  
         [0214]    In the figure, a convexity  314  installed in hub  303   b , and a concavity  157  installed at spindle part  155   b  of the rotor and formed so as to engage with convexity  314 . Convexity  314  and concavity  157  that engage with each other are installed at three different parts of hub  303   b  and spindle part  155   b  respectively.  
         [0215]    As shown above, recording medium cartridge  300  with hub  303   b  constructed as indicated above is inserted into insertion and ejection port  180  of FDD unit  100 , the cartridge slides over chucking magnet  154  by convexity  314  of the hub  303   b , jumps over centering ball  158 , and then the hole  313  and centering ball  158  get engaged with. Because hub  303   b  in this state has a tiny gap from spindle part  155   b  due to convexity  314 , sucking force of chucking magnet  154  for hub  303   b  is small. Next, spindle part  155   b  rotates. As the convexity  314  and concavity  157  and get engaged with, the chucking magnet  154  and the hub  303   b  overlay, strengthening sucking force of chucking magnet  154 , performing centering of recording medium  301  correctly, and completes chucking. Because the sucking force of the chucking magnet does not get strengthened until centering operation is complete, chucking mechanism with high centering performance of recording medium  301  can be achieved according to this embodiment.  
         [0216]    Although concavity  157  and convexity  314  are placed on three different parts in this example, it is possible to install more than three. An example of placing concavity  157  on spindle part  155   b  and convexity on hub  303   b  is given, but the relationship of concavity and convexity may be reversed. It goes without saying that shapes other than that can be also applied so long as they engage with each other.  
       Embodiment 4  
       [0217]    This Embodiment shows another example regarding the chucking mechanism of the recording medium drive actuator.  
         [0218]    [0218]FIG. 9A and FIG. 9B are cross sectional views showing a case of inserting a recording medium cartridge into FDD unit  100 . FIG. 9C is a cross sectional view showing the top of FDD unit  100 .  
         [0219]    [0219]FIG. 10A shows a top view of spindle part  155   c . FIG. 10B shows a slanted view of the hub.  
         [0220]    In the figure, an elastic and modifiable retainer  156  is holding three centering balls  158   c.  Also, a concave groove  315  is installed around the circumference of hub  303   c . Chucking magnet  154   c  is placed in the center of spindle part  155   c . In Embodiment 3, convexity  314  is placed on hub  303   b  of recording medium  301 . The center is centering hole  313  of magnetic material. But, the center of hub  303   c  of this embodiment is covered. Concave groove  315  is installed around the circumference of hub  303   c  and three centering balls  158   c  that are to be engaged with the concave groove  315  are placed for spindle part  155   c . Also, spindle part  155   c  has a taper part  156   a  which is to be connected with the inner circumference of the centering ball  158   c . The centering balls  158   c  are positioned between taper part  315   a  outside of concave groove  315  and taper part  156   a  of spindle part  155   c . When recording medium cartridge  300  is inserted into insertion and ejection port  180  of FDD unit  100 , the hub  303   c  gets engaged in with the centering balls  158   c  and slides over centering balls  158   c , getting inserted separately from chucking magnet  154   c .  
         [0221]    As recording medium cartridge  300  is further inserted, and the center of hub  303   c  comes close to chucking magnet  154   c , all three centering balls get engaged with concave grooves  315 , upon which hub  303   c  and chucking magnet  154   c  are sucked and retained, completing positioning and load state.  
         [0222]    Because positioning, sucking, and retaining are not performed until the center of hub  303   c  comes close to chucking magnet  154   c  in this embodiment, more accurate centering can be performed. Moreover, an initial operation to rotate spindle part  155   c  for sucking and retaining is not required, this embodiment is advantageous in shortening load time.  
       Embodiment 5  
       [0223]    This embodiment shows yet another example regarding the positioning means of the recording medium drive actuator.  
         [0224]    [0224]FIG. 11 is a cross sectional view showing a side of FDD unit  100 . In the figure, a spring  160  has a projection and has a function of positioning recording medium  301 . Examples of positioning recording medium  301  using centering balls have been given in previous examples. In this embodiment, however, as shown in FIG. 11, spring  160  is engaged with the center hole in the center of spindle part  155  to perform centering of recording medium  301 . This embodiment has an advantage in reducing the number of parts as centering balls and ball preload springs which is an energization means are combined in one structure. It is also advantageous in that enough avoidance space can be taken for the spring  160  while inserting or removing recording medium cartridge  300 .  
       Embodiment 6  
       [0225]    [0225]FIG. 12 and FIG. 13 are cross sectional views showing the sides of FDD unit  100  according to another example of this invention. Of them, FIG. 12 shows the insertion of recording medium cartridge  300  in progress from insertion and ejection port  180 . FIG. 13 shows the completed load state as recording medium cartridge  300  has been inserted.  
         [0226]    In the figure, a head avoidance lever  130 , an extension lever  131 , a head energization lever  132  are shown. Head avoidance lever  130  and head energization lever  132  are secured on the ends by the same shaft  133  and operate in uniform. Although not shown in the figures, the lower head of read/write head  101  is energized in the upward direction so that recording medium  301  can be sandwitched between the lower and upper heads. Also, extension lever  131  is energized in the direction of insertion and ejection port  180  with springs and so on. In addition, a cylindrical end  130   a  of avoidance lever  130  is energized in the direction of extension lever  131  (upward) with springs and so on. Therefore, head energization lever  132  is pushing down on the lower head of read/write head  101  toward downward direction.  
         [0227]    Next, operation is explained with reference to figures.  
         [0228]    When the recording medium cartridge  300  is inserted from insertion and ejection port  180 , shutter  304  of recording medium cartridge  300  opens. When recording medium  301  comes close to read/write head  301 , the end of recording medium cartridge  300  gets engaged with extension lever  131 , which is pushed into the insertion direction of recording medium cartridge  300 . Then, the end opposite to the end engaged with recording medium cartridge  300  gets engaged with the head avoidance lever  130  and pushes it. Head avoidance lever  130  rotates counterclockwise with shaft  133  as the center. As head avoidance lever  130  rotates counter-clockwise, head energization lever  132  also rotates counter-clockwise, thereupon releasing the force pushing down the lower head of read/write head  101 . The lower head moves upward and gets engaged with the inserted recording medium  301 .  
         [0229]    Because the lower head can be avoided at least as much as the thickness of the recording medium drive actuator by using the avoidance means of read/write head  101  of this embodiment, there is no need of taking extra thickness for head avoidance. This allows the thinner construction of FDD unit  100  in terms of the device thickness.  
         [0230]    Although the above embodiment illustrates the avoidance means of the lower head under the construction of a recording medium to be sandwiched by two heads, it goes without saying that this head avoidance means can be used for the construction in which only one head is provided beneath a recording medium.  
       Embodiment 7  
       [0231]    The previous embodiments show the cases in which FDD unit  100  is a box-type frame. Insertion and ejection port  180  is provided on one side of the box. Recording medium cartridge  300  is inserted horizontally from this insertion and ejection port. This embodiment, however, shows the construction of the FDD, where the frame of FDD unit  100  is separated into two frames, an upper frame and a lower frame. A rotation shaft is provided at the end of this separated frame, and the upper frame opens with this rotation shaft as the pivot.  
         [0232]    [0232]FIGS. 14, 15, and  16  show the construction of FDD unit  100   a  in accordance with Embodiment  7 . FIGS. 14 and 15 show the unload states and FIG. 16 shows the load state. Furthermore, FIG. 14 indicates that read/write head  101  is positioned on the end of inner circumference of recording medium  301  and FIG. 15 indicates that read/write head  101  is positioned on the end of outer circumference of recording medium  301 .  
         [0233]    In the figure,  100   a  is a modified version of the FDD unit. A lower frame  110   a , an upper frame  110   b , a cartridge holder  120  mounted on upper frame  110   b , a sub-cover (sub-frame)  121 , and upper frame  110   b  and sub-frame  121  are engaged with at a certain supporting point (not shown). A rotation pivot  122  supports the rotation of upper frame  110   a  and lower frame  110   b , and rotation pivot  123  supports the rotation of sub-frame  121  up. Rotation pivot  123  of sub-frame  121  is placed inside rotation pivot  122  that rotates the frames. A rotor  150   a , spindle shaft  155   a  are also shown. The relationship between this rotor  150   a  and spindle shaft  155   a  is the same as the prior art. With rotor  150   a  as the center shaft, spindle shaft  155   a  is supported to freely rotate by lower frame  110   a  via bearing  170 .  
         [0234]    Next operation is explained.  
         [0235]    In order to insert recording medium cartridge  300  from FDD unit  100   a , and when FDD unit  100   a  is, for instance, being inserted into a general-purpose slot  200  shown in FIG. 1, first of all, eject button  222  must be pressed to eject FDD unit  100   a  outside in order to make this FDD unit  100   a  a unit. Then, as FDD unit  100   a  has been made a unit, upper frame  110   b  is rotated with rotation pivot  122  as the center so as to open the upper frame slantly against lower frame  110   a  of FDD unit  100   a . Sub-frame  121  opens in linkage, but because rotation pivot  123  of sub-frame  121  is inside rotation pivot  122  of the frame, the angle of opening sub-frame  121  becomes wider than the opening angle of upper frame  110   b . Therefore, the upper head of read/write head  101  is avoided higher than upper frame  110   b . Next, recording medium cartridge  300  is inserted into cartridge holder  120 . Because the upper head of read/write head  101  is being avoided higher than cartridge holder  120  at this time, it does not have to make contact with recording medium cartridge  300  being inserted.  
         [0236]    After recording medium cartridge  300  has been inserted into cartridge holder  120 , upper frame  110   b  gets engaged with lower frame  110   a , thereupon closing the frame. Recording medium  301  is positioned by spindle shaft  155   a  and sucked and retained by chucking magnet  154 . At the same time, the upper head of read/write head  101  is energized by sub-frame  121 , engaged with the top surface of recording medium  301 , thereby completing load state.  
         [0237]    According to this embodiment, upper frame  110  is opened in order to retain recording medium  301 . Because its positioning in relation to recording medium drive actuator  140  is performed by closing upper frame  110   b , the thickness to avoid spindle shaft  155   a  is no longer required even when the construction of spindle shaft  155   a  is the same as the related art. Because of this, even when the construction of rotor  150   a  and spindle shaft  155   a  is as simple as the related art, FDD unit  100   b  can be made thinner. Moreover, by providing sub-frame  121  that engages with upper frame  110   b , the upper head of read/write head  101  can be protected under an unload state.  
       Embodiment 8  
       [0238]    This embodiment gives a modified example of Embodiment 7.  
         [0239]    [0239]FIG. 17, FIG. 18, and FIG. 19 show the construction of FDD unit  100   b  in accordance with Embodiment 8. FIG. 17 and FIG. 18 show the unload state, and FIG. 19 shows load state. FIG. 17 is an illustration of read/write head  101  positioning on the end of inner circumference of recording medium  301 , and FIG. 18 shows that read/write head  101  is positioned on the end of outer circumference of recording medium  301 .  
         [0240]    In the figure, a modified example of FDD unit  100   b , cartridge holder  120   b , and rotation pivot  122   b  of cartridge holder  120   b  are shown. The difference from the previous Embodiment 7 is that the rotation pivot  122   b  of the upper frame  110   b  is provided on the inside of the rotation pivot  123   b  of the sub-frame  121   b .  
         [0241]    Next, operation is explained with reference to figures.  
         [0242]    It is the same as Embodiment  7  in that FDD unit  100   b  must be made a unit in order to insert recording medium cartridge  300 . Next, as FDD unit  100   a  has been made a unit, upper frame  110   b  is rotated with rotation pivot  122  as the center so as to open the upper frame slantly against lower frame  110   a  of FDD unit  100   a . Cartridge holder  120   b  opens in linkage. Because rotation pivot  122   b  of cartridge holder  120   b  is inside of rotation pivot  123   b  at this time, the angle of opening cartridge holder  120   b  becomes wider than the opening angle of sub-frame  121   b.  Therefore, the upper head of read/write head  101  is avoided outside of cartridge holder  120   b . Next, recording medium cartridge  300  is inserted into cartridge holder  120 . Because the upper head of read/write head  101  is avoided outside of cartridge holder  120   b  at this time, it does not have to make contact with recording medium cartridge  300  being inserted.  
         [0243]    After recording medium cartridge  300  is inserted into cartridge holder  120   b , upper frame  110   b  gets engaged with lower frame  110   a , thereupon closing the frame. Recording medium  301  is positioned by spindle shaft  155   a  and sucked and retained by chucking magnet  154 . At the same time, the upper head of read/write head  101  is energized to lower frame  110   b , and engaged with the top surface of recording medium  301 , and the load state has been complete.  
         [0244]    According to this Embodiment, the effect not only the same as the Embodiment 7 can be achieved but also the number of parts can be reduced.  
       Embodiment 9  
       [0245]    An example regarding the invention of the recording medium drive actuator will be explained.  
         [0246]    [0246]FIG. 20A is a top view showing the part of the recording medium drive actuator. FIG. 20B shows the construction of the stator core before being bent. FIG. 21 shows a slanted view of the construction of the stator which is a part of the recording medium drive actuator.  
         [0247]    In the figures, recording medium drive actuator  140 , and stator core  144  are secured with stator core supporting pin  1441 . The construction of stator  141  has so far been structured with the teeth and coil. But in this embodiment, stator  141  is divided into multiple stator elements  145 . Coil  146  is wound around coil bobbin  147 . Stator element  145  is made up of coil bobbin  147 , center core  148  which is the core of coil bobbin  147 . When mounting coil bobbin  147  on center core  148 , it is mounted by welding, or secured with caulk. This embodiment shows an example of the recording medium drive actuator driven by three phases. One block is made up of three stator elements  145  of phases U, V, and W. The midpoint of each block of stator core  144 , or the vicinity of the supporting point by stator core supporting pin  1441  is dented to make bending possible. As stator core  144  is bent in the direction of arrow K from the state shown in FIG. 20B, stator core  144  in the shape shown in FIG. 20A can be easily produced. Although not shown in the figure, the winding of each stator element  145 , from the opposite direction from the direction of inserting coil bobbin  147  into center core  148 , coil bobbin  147  in inserted into the handle (not shown) of the winding machine so as to enable to perform winding concurrently with the construction of recording medium drive actuator  140 . Two or more handles are aligned on the winding machine. By taking wider space between the coil bobbins  147  inserted into the handles, winding can be performed simultaneously and at high speed for each coil bobbin  147 . As a winding method, the uniform phases of U, V, and W can be performed at the same time, or they can be sequentially performed in order of U, V, and W.  
         [0248]    Due to the above construction, recording medium drive actuator  140  can be made thinner as a whole. In addition, by winding coils on the coil bobbins, and by mounting these coil bobbins on the center core, winding of coils becomes easier. Moreover, pitches between each stator of recording medium drive actuator  140  can be made shorter than the distance incapable of automatic winding when automatic winding machine is used for winding coils directly on the teeth. Therefore, compact and high output recording medium drive actuator  140  is realized.  
       Embodiment 10  
       [0249]    This embodiment shows another example of the construction of stator element  145  of recording medium drive actuator  140  set forth in Embodiment 9.  
         [0250]    [0250]FIG. 22 and FIG. 23 show another example of FIG. 21. In the previous embodiment 9, the cross section of coil bobbin  147  is presented as a square cylinder. However, coil bobbin  147   b  illustrated in FIG. 22 is provided with a slit which is connected in horizontal direction from one end to the other of the square cylinder type of coil bobbin. In this case, center core  148   b  is shaped so that it gets engaged with coil bobbin  147   b.  Coil bobbin  147   b  shaped in this way is advantageous because it can be manufactured easily from the magnetic material sheet using the sheet metal press.  
         [0251]    It is also possible to use cylindrical coil bobbin  147   c  as shown in FIG. 23.  
         [0252]    Similarly to the case of FIG. 22, center core  148   c  is formed so that it gets engaged with coil bobbin  147   c.  Cylindrical coil bobbin  147   c  is advantageous in obtaining stator element  145   c  of stable quality because it is easy to keep wire tension uniform in winding coil in this way.  
       Embodiment 11  
       [0253]    This embodiment explains another example regarding the construction of the recording medium drive actuator.  
         [0254]    [0254]FIG. 24 is a cross sectional view of FDD unit  100 . The construction of the recording medium drive actuator of this example is instead of spindle shaft  48 , which works as positioning means and supporting shaft in the related art of FIG. 81, a cylindrical bearing  170  is provided as the supporting shaft. Spindle part  155  is placed on the inner circumference to freely rotate. A hole is provided in the center of this spindle part  155 . Centering ball  158  which is the positioning means and ball preload spring  159  are mounted on the hole. In this example, the spindle part  155  is connected with rotor yoke  152  by means of a, for instance, caulk, and so on.  
         [0255]    According to this embodiment, because a hole is provided in the center of spindle part  155 , centering ball  158  which is the positioning means and ball preload spring  159  shown, for instance, in Embodiment 1 can be placed in the center.  
       Embodiment 12  
       [0256]    This embodiment shows another example concerning the construction of the recording medium drive actuator.  
         [0257]    [0257]FIG. 25 is a cross sectional view of FDD unit  100 . In the figure, an another example of rotor  150   c , another example of rotor yoke  152   c , and another example of spindle part  155   c  are shown. The difference from Embodiment 11 is in that rotor yoke  152   c  is combined with the part material (material  155   a  in FIG. 24) for securing it on the rotating side  170   a  of the bearing part (bearing  170 ), placing spindle part  155   c  inside combined rotor yoke  152   c.    
         [0258]    According to this embodiment, because rotor yoke  152   c  is placed so as to freely rotate against the bearing, rotor yoke  152   c  can be rotated without setting spindle part  155   c  inside rotor yoke  152   c , thus enabling a unit testing to be performed only for this rotor yoke  152   c .  
       Embodiment 13  
       [0259]    This embodiment shows an example of the head drive actuator of this invention.  
         [0260]    [0260]FIG. 26 is a slanted view showing part of step motor  106  which is a main part of head drive actuator  105 . FIG. 27 shows a top view omitting a shield cover shown in FIG. 26, and shows the construction of the rotor and stator. In addition, FIG. 28 is a cross sectional view seen from A-A point shown in FIG. 27 to the direction of arrow. FIG. 29 is a cross sectional view seen from B-B point in FIG. 27 to the direction of arrow. FIG. 30 is a cross sectional view seen from C-C point shown in FIG. 27 to the direction of arrow. FIG. 31 is a cross sectional view seen from D-D point shown in FIG. 27 to the direction of arrow.  
         [0261]    In the figure, stator  161  is made up of coil  162 , a first stator yoke  163 , and a second stator yoke  164 . As shown in FIG. 28 through FIG. 31, three teeth are provided to the opposite side of rotor  165 , which is discussed later. The position of these teeth differs from phase angle of 90°, namely 11.25° in machine angle. Furthermore, coil U and coil U bar of coil  162  shown in FIG. 27 are formed with coils having the phase angle different in 180°. Similarly, coil V and coil V bar are formed with coils having the phase angle different in 180°. Also, rotor  165  is magnetized at different poles on one end and the other in the horizontal direction. Namely, rotor magnet  166  is bipolared as a whole and four rotor yokes  167  having eight radial convexities on one end and the other of this rotor magnet make up the rotor. Four rotor yokes  167  are all the same form. But rotor yoke  167  on the side shown in FIG. 28 and FIG. 29 and rotor yoke  167  on the side shown in FIG. 30 and FIG. 31 are structured so as to differ by 180°in phase angle, namely 22.5° in terms of machine angle. Based on the above construction, the drive method is unipolar method, and a step motor that drives at step angle 11.25° at the time of driving one phase excitation can be achieved.  
         [0262]    According to this embodiment, because coil  162  is placed on both sides of rotor  165 , the turns of the coil can be increased. This is advantageous in outputting torque required to perform carriage drive and in making the head drive actuator itself thinner than 5.0 mm, the PCMCIA standard type-2. Furthermore, rotor magnet  166  used for this embodiment is bipolared, and a magnet like this can be produced at relatively low cost, thereby enabling the entire cost of head drive actuator to be lowered.  
       Embodiment 14  
       [0263]    This embodiment shows another example of the head drive actuator described in Embodiment 13. FIG. 32 shows a top view of step motor  106   b  of this embodiment with shield cover  169  removed, and indicates the construction of the rotor and the stator. Furthermore, FIG. 33 is a cross sectional view seen from E-E point shown in FIG. 32 to the direction of arrow. FIG. 34 is a cross sectional view seen from F-F point shown in FIG. 32 to the direction of arrow. FIG. 35 is a cross sectional view seen from G-G point shown in FIG. 32 to the direction of arrow. FIG. 36 is a cross sectional view seen from H-H point shown in FIG. 32 to the direction of arrow.  
         [0264]    In the figure, stator  161   b  is made up of coil  162 , and a first stator yoke  163   b , and a second stator yoke  164   b.  First stator yoke  163   b  and second stator yoke  164   b  are provided with two teeth on the surface opposite to rotor  165   b  which is explained later as shown in FIG. 33 through FIG. 36. The position of teeth of stator yoke  163   b  in FIG. 33 and that of stator yoke  163   b  in FIG. 35 are symmetrically arranged. Similarly, the teeth of stator yoke  164   b  of FIG. 34 and those of stator yoke  164   b  in FIG. 36 are arranged symmetrically. Therefore, first stator yoke  163   b  differs from second stator yoke  164   b  by 180° in phase angle and 45° in machine angle. Stator yoke  163   b  in FIG. 33 differs from stator yoke  164   b  in FIG. 34 by 90° in phase angle and by 22.5° in machine angle because they are arranged to be symmetrical when they are reversed. Unlike rotor  165  of Embodiment 13, rotor  165   b  is radially magnetized at 8 polers toward the direction of circumference. Among coils  162  shown in FIG. 32, coil U and coil V are not shown in the figure, but coil U bar and coil V bar having a phase angle different by 180° from each other can be formed by running reverse current to them. Based on the construction explained above, the drive method of Embodiment 14 is a bipolar method and a step motor driven at 22.5° in step angle at the time of driving with one phase excitation can be achieved  
         [0265]    According to this embodiment, because coils  162  are arranged on both sides of rotor  165   b  similarly to Embodiment 13, the turns of the coil can be increased. It is therefore advantageous in that the torque required to perform carriage drive is outputted and the head drive actuator itself can be made thinner. Moreover, because the step motor of this embodiment applies a general bipolar method as its drive method, a drive circuit on the market can be employed.  
       Embodiment 15  
       [0266]    This embodiment shows one example of the recording medium cartridge of this invention.  
         [0267]    [0267]FIG. 37A and FIG. 37B show the state in which a shutter is being closed.  
         [0268]    [0268]FIG. 37A gives its top view and FIG. 37B is the side view. FIG. 38A and FIG. 38B show the opening state of the shutter. FIG. 38A is the top view, and FIG. 38B is the side view.  
         [0269]    In the figures, an opener band  306 , an opener latch  307 , guide rollers  308  and  309  are shown. Although not shown in the figures, this construction is possible to apply tension to at least one point of opener band  306 . Opener band  306  is connected with shutter  304  on its both ends and connected with opener latch  307  in halfway. As shown in FIG. 38A, when recording medium cartridge  300  is inserted into the direction of X, opener latch  307  is moved toward the direction of -X by the lever provided to the storage device. As this opener latch  307  and shutter  304  connected with each other by opener band  306  are pulled in the -Y direction, window  305  is released, thereupon exposing recording medium  301 . At this time, no part material for cartridge case  302  nor part material for shutter  304  exist in area S. In order to pull out recording medium cartridge  300  in the opposite direction, opener latch  307  is moved in the X direction by the lever of the storage device, and shutter  304  is moved in the Y direction by the connected opener band  306 , and window  305  closes.  
         [0270]    According to this embodiment, shutter  304  can be opened or closed by opener band  306 . When shutter  304  is in the opened state or closed state, by keeping this state with opener latch  307 , malfunction of shutter opening and closing can be prevented. In addition, when shutter  304  is in the opened state, area S is exposed entirely, thus making it possible to reduce the avoidance operation of the read/write head of the FDD using this recording medium cartridge. It is therefore advantageous in getting thinner FDDs. On top of that, effects indicated above can be achieved by means of relatively simple construction so far set forth.  
         [0271]    The FDD of this invention is a device which is compatible with a card type storage that can be inserted into and removed from an information processing device. The recording medium or recording medium cartridge are to be replaced. The FDD of the present invention is characterized by the recording medium drive actuator to rotate the recording medium, the head to read or write data on the recording medium, the carriage on which to mount the heads, the head drive actuator to determine the moving position of the heads, the mechanism to insert or remove the recording medium from the storage, the circuit to control the read/write operation and the recording medium drive actuator, and so on, and the connector that connects or disconnects the storage.  
         [0272]    Another prime characteristics is that the thickness and the width of the device are less than 5 mm and 54.1 mm, respectively.  
         [0273]    Moreover, the recording medium is characterized in that it is contained in the cartridge of less than 1.8″ in diameter, less than 2 mm in thickness, and less than 54 mm in width.  
         [0274]    In addition, the recording medium or recording medium cartridge is loaded or unloaded by inserting or removing it in the same direction to the FDD.  
         [0275]    With respect to the center of the rotor of the recording medium drive actuator, it has a function of centering the recording medium and determining the rotation center. It is supported by springs, and so on, and preloaded, and has one or more balls which can be floated or sunk or rotated. The rotor has a chucking magnet to suck the hub supporting the recording medium, and the hub is provided with taper surface on its outer circumference. The rotor has the hole or dent to be connected to the ball in the center.  
         [0276]    With respect to the vicinity of the rotor center of the recording medium drive actuator, it is provided with three or more balls or needles having the function of centering the recording medium and determining the rotation center. There is also a retainer which retains and engages rotating balls or needles freely. The center of the rotor is provided with a chucking magnet to suck the hub connected with the recording medium.  
         [0277]    With respect to the rotor of the recording medium drive actuator, it has a spring material with a projection or a hole having the function of centering the recording medium or determining the rotation center, and the space for the displacement of spring materials and so on. The recording medium has the hole or projection which engages with the above mentioned projection or hole.  
         [0278]    Part of the carriage can be rotated. At the end of the carriage, the head is held by means of the arm, which rotates in line with the insertion or removal of the recording medium or recording medium cartridge. The head, therefore, touches or leaves from the recording medium. That is, the head touches the recording medium when the recording medium or recording medium cartridge is inserted, and the head leaves from the recording medium when the recording medium or recording medium cartridge is removed.  
         [0279]    In addition, it is characterized in that the recording medium or recording medium cartridge is inserted or removed from the recording medium cartridge holder which opens or closes slantly against the cabinet of the storage device.  
         [0280]    Moreover, it is characterized in that it is provided with the recording medium cartridge holder which contains the recording medium cartridge to be inserted slantly and works as a protective cover of the storage, and the sub cover which covers the recording medium cartridge holder from the top surface.  
         [0281]    Furthermore, the recording medium cartridge holder and the sub cover have their independent rotation pivots. The rotational radius of the sub cover is smaller than the rotational radius of the recording medium cartridge holder. The rotational pivot of the sub cover is inside the rotational pivot of the recording medium cartridge holder, and it rotates in line with the rotation of the recording medium cartridge holder. When the recording medium is inserted, a space is created between the sub cover and the recording medium cartridge holder so that the avoidance of the head is made possible.  
         [0282]    It is also characterized in that the rotation radius of the sub cover is larger than the rotation radius of the medium holder, as the rotation pivot of the sub cover is outside of the rotation pivot of the recording medium cartridge holder. The sub cover rotates in line with the rotation of the medium holder. When the recording medium is inserted, a space is created between the recording medium cartridge holder and the sub cover so that the avoidance of the head can be made possible.  
         [0283]    In addition, part of the carriage on which to mount the read/write head can be rotated. The arm is provided according to the rotation of the recording medium cartridge holder, and the head is provided at the end of the arm by means of spring materials and so on.  
         [0284]    In addition, the recording medium drive actuator of this invention is characterized in that it is provided with the stator, drive coil wound around the teeth of the stator, and the rotor, where, the coil is wound by bobbins of magnetic material and fixedly inserted to the stator.  
         [0285]    It is also characterized in that the stator is provided with one block or more, one block being made up of the teeth the number of which is equivalent to the number of drive phases. The coil is wound by bobbins of magnetic material and fixedly inserted to the stator.  
         [0286]    The bobbins are characterized in that they are shaped in the abbreviated form of Japanese katakana ko, or ro, or abbreviated circular.  
         [0287]    The bearing of the recording medium drive actuator is characterized in that it is placed on the outer circumference of the rotor connected with the rotor yoke supporting the rotor magnet, and an avoidance space is created at the rotor center for the centering balls.  
         [0288]    The bearing of the recording medium drive actuator is characterized in that it is made up of the cylinder with a built-in part of the rotor yoke supporting the rotor magnet, and the balls or the ball bearing.  
         [0289]    The head drive actuator of this invention is made up of the rotor of abbreviated cylinder magnet supported for free rotation or the rotor consisted of the magnet and the rotor yoke, the stator yoke provided horizontally as opposed to the rotation shaft of the rotor as the symmetry shaft, and drive coil, to perform a step drive by a certain angle.  
         [0290]    The head drive actuator of this invention is characterized in that it has the lead screw having spiral grooves that connect and slide against the cylindrical needles set on the carriage on which to mount the head, and the rotor connected with the lead screw, and the pivot bearing that accepts the end of the lead screw at the end of the lead screw, and the spring that provides preload from the other end of the lead screw. By performing a step rotation by a certain angle, the drive position of the carriage is determined.  
         [0291]    The head drive actuator of this invention is characterized in that it has the thickness of less than 5 mm.  
         [0292]    It is also characterized in that it has the rotor magnet magnetized in the direction of rotation shaft of the rotor, and the rotor yoke, and the stator yoke that opposes these rotor yokes from a certain gap.  
         [0293]    The rotor magnet is also characterized in that it is magnetized in the radial direction of the rotation shaft.  
         [0294]    The stator and rotor are characterized in that they are constructed by paired parts or more.  
         [0295]    The recording medium cartridge of this invention is characterized in that it has the case and the shutter, and the shutter is set to open and close in the direction perpendicular to the insertion of the cartridge into the storage, and the latch for opening and closing the shutter is provided on the side of the cartridge, and the latch and the shutter are connected with a band.  
         [0296]    The recording medium cartridge is characterized in that the insertion direction side, or part of materials of the outer circumference of the shutter for opening or closing the window through which the read/write head makes an access and the cartridge case into the storage, are removed.  
       Embodiment 16  
       [0297]    Hereinafter, an embodiment of the present invention will be described with reference to the attached figures. FIG. 39 shows a perspective view of an external sight of the FDD unit  100 . FIG. 40 shows a perspective view of the structure of the internal of the FDD unit  100  in which the upper cover  113   a  is removed. FIG. 41 shows a perspective view of the FDD unit  100  in which the upper cover  103   a  is removed and the recording medium cartridge  300  is mounted. FIG. 42 shows a part of the cross sectional side view of the FDD unit  100 .  
         [0298]    In the figure, a frame  110  supports the whole of the FDD unit  100 . In the frame  110 , a cartridge receiving face  110   s  is a face to mount the recording medium cartridge  300  horizontally. Side wall parts  111   a  and  111   b  extend in the longish direction of the unit and are mounted in the vertical direction to the cartridge receiving face  110   s.  The frame  110  is opened forwardly and a taper face  110   c  is provided so that the recording medium cartridge  300  is inserted easily. An insertion and ejection port  180  of the cartridge protects the internal of the frame  110  and the FDD unit  100 . The insertion and ejection port  180  is composed of the upper cover  113   a  mounted on the top face of the FDD unit  100 . The center of the cartridge receiving face  110   s  has a circular center hole  110   d.  On the other side of the insertion and ejection port  180  from the center hole  110   d,  a rectangular head access portion  110   e  which extends in the longish direction is provided. The frame  110  is sandwitched between the upper cover  113   a  and the lower cover  113   b . The external shape of the FDD unit  100  covered by both of the covers  113   a  and  113   b  is in accordance with type 2 of PCMCIA. Under the frame  110 , the recording medium drive actuator  140  for rotating and driving the recording medium  301  in the recording medium cartridge  300  is located. The recording medium drive actuator  140  is composed of a dishing shape of rotor  150 , the chucking magnet  154  to absorb a metal hub, not shown in the figure, fixed in the recording medium  301  the centering ball  158  which is the center of rotation of the rotor  150  and so on. The centering ball  158  and the chucking magnet  154  are facing to the upper side of the cartridge receiving face  110   s  through the center hole  110   d  of the frame  110 .  
         [0299]    [0299]FIG. 43 shows an enlargement of the outskirts of the head access portion  110   e  of the frame  110  and a perspective view seen from the top face of the FDD unit  100 . FIG. 44 shows a side cross sectional view of unload state in which the read and write procedure cannot be performed and the head  101  is unloaded. FIG. 45 shows a side cross sectional view of the load state in which read/write procedure is possible. FIG. 46 shows a perspective view of a head unload mechanism. FIG. 46 shows a perspective view seen from the top face of the FDD unit  100 . FIG. 47 shows a perspective view of the FDD unit  100  wherein the frame  110 , head frames  104   a  and  104   b  in FIG. 46 are removed and only the head unload mechanism is left.  
         [0300]    In the figure, at the head access portion  110   e , a read/write head  101  is located to read and write the information for the recording medium  301 . An upper head  101   a  is situated on the side of the cartridge receiving face  110   s  and a lower head  101   b  is situated on the side of the bottom. Further, both of the heads  101   a  and  101   b  are positioned respectively against each of the ends of the upper arm  104   a  and the lower arm  104   b  extending in the longish direction. The other ends of the arms  104   a  and  104   b  are situated on the carriage  102 . With the carriage  102 , both of the arms  104   a  and  104   b  move back and forth by the head drive actuator (not shown in the figure). The end of the upper arm  104   a  is fixed on the carriage  102  and the lower arm  104   b  has a rotation support at the carriage  102 . By using the lower arm spring  400  composed of flexible plate material whose end is fixed at the carriage  102 , the lower arm  104   b  is always given a tension in the direction of being shut with the upper arm  104   a.  The carriage  102  has a peaking shape of arm stopper  102   a , which regulates the rotation angle of the lower arm  104   b  toward the side of the upper arm  104   a.  The lower arm  104   b  is restricted to rotate within a range of a defined angle. A head lifter  402  is composed of a lifter  402   a , an unload lever  402   b , a rotating force receiver  402   c , and a tension receiver  402   d . In order to make the lower head  101   b  enter to the load state or the unload state, the lifter part  402   a  rotates when the unload lever  402   b  rotates. Then, by moving the lower arm  104   b  up and down, the load state or the unload state is achieved. The unload lever  402   b  is supported to be rotatable freely by a lever supporter  110   g.  The lever supporter  110   g  is mounted on the frame and sticking out from the frame  110 .  
         [0301]    The other end of the lifter  402   a  of the head lifter  402  has the rotating force receiver  402   c . The rotating force receiver  402   c  receives the transmission force from the eject shaft  403  and rotates the unload lever  402   b . An tension receiver  402   d  is positioned a little nearer the lifter part  402   a  than the rotating force receiver  402   c  and always give the rotating force to the unload lever  402   b . The tension receiver  402   d  receives the tension from almost U-shaped rotating force spring  404  whose end is fixed on the frame  110 . By giving the force in the direction to which both faces of the U-shape encounters are separating, the tension receiver  402   d  always tends to rotate to the side of the upper cover  113   a , namely, in the direction of an arrow A in the figure. The rotating force receiver  402   c  is located in the side wall part  111   a  of the frame  110 . The rotating force receiver  402   c  has a top bent on the side of the lower cover  113   b . The top contacts an end part  403   a  of the eject shaft  403 .  
         [0302]    [0302]FIG. 48 shows an external perspective view of the eject shaft  403 . The eject shaft  403  is able to slide in the longish direction in the side wall part  111   a  of the frame  110 . An eject button  405  is fixed at an end of the eject shaft  403  on the side of the insertion and ejection port  180 . The other end is a terminate part  403   a  by decreasing the thickness of the eject shaft  403  to the end part. The eject shaft  403  has a spring stopper  406   a  at almost center part of the longish body. The spring stopper  406  engages with a coil spring around the eject shaft  403 .  
         [0303]    [0303]FIG. 49 shows a perspective view of the side wall part  111   a  having a notch  110   k . The notch  110   k  gives an open port from outside. In the notch  110   k , the eject shaft  403 , the spring stopper  406  and a coil spring  407  are exposed. The eject shaft  403  is placed inside of the coil spring  407 . An end of the coil spring  407  contacts the spring stopper  406 . The other end of the coil spring  407  contacts the spring stopper face  110   m  of the frame  110  on the opposite side of the insertion and ejection port  180 . The length of the open port of the notch  110   k  is more than the length for which the coil spring  407  can heap extension operation. Therefore, the coil spring  407  extends from the spring stopping face  110   m  as a base position and always gives the tension to the eject shaft  403  in the direction of the insertion and ejection port  180  through the spring stopper  406 .  
         [0304]    [0304]FIG. 50 shows a perspective view of the shaft barb stopper  408 . The shaft barb stopper  408  controls the movement in the longish direction of the eject shaft  403  by insertion and ejection of the recording medium cartridge  300 . The shaft barb stopper  408  is composed of flexible plate material having an elastic force. An end of the shaft barb stopper  408  forms a curved convexity  408   a  and the other end is fixed on the frame  110 . The convexity  408   a  of the shaft barb stopper  408  is engaged with a barb stopper notch  403   e.  The barb stopper notch is notched in the longish direction of the eject shaft  403 . The convexity  408   a  is possible to be bent to the side of the lower cover  113   b  so as to release the engage state of the shaft barb stopper  408  and the barb stopper notch  403   e.    
         [0305]    Next, an explanation is made for the operation of the head unload mechanism when the recording medium cartridge  300  is inserted in the FDD unit  100 . In this operation, the unload state, in which read and write procedure is impossible, changes to the load state, in which read and write procedure is possible. FIG. 51 shows a perspective view of the head unload mechanism under the unload state. In the figure, the frame  110  is not shown.  
         [0306]    The recording medium cartridge  300  is inserted from the insertion and ejection port  180  and slides on the cartridge receiving face  110   s  and comes in contact with the convexity  408   a  of the shaft barb  408 . The convexity  408   a  bends by being pressed by the recording medium cartridge  300  to the side of the lower cover  113   b . Then, the engage state of the barb stopper notch  403   e  of the eject shaft  403  is released. The eject shaft  403  is forced to slide to the side of the insertion and ejection port  180  by the coil spring  407 . As a result, the eject shaft  403  moves in the direction of the insertion and ejection port  180  until the spring stopper  406  contacts the frame side wall la on the opposite side of the spring stopper face  110   m.  The eject button  405  comes out from the frame  110 . Under the unload state, the rotating force receiver  402   c  contacts the higher face  403   c  of the taper face  403   b  of the eject shaft  403 , which is on the side of the insertion and ejection port  180 . With the eject shaft  403  moving, the taper face  403   b  slides. The rotating force receiver  402   c  slides down the taper face  403   b  and contacts the lower face  403   d  which is on the opposite side of the insertion and ejection port  180 . The rotating force receiver  402   c  rotates around the unload lever  402   b . When the rotating force receiver  402   c  rotates, due to the tension of the rotating force spring  404 , the unload lever  402   b  rotates in the direction of the arrow A in the figure. With the rotation of the rotating force receiver  402   a , the lifter part  402   a  rotates in the same direction. When the lifter part  402   a  is rotated and separated from the lower arm  104   b , the lower arm  104   b  rotates until it comes in contact with the arm stopper  102   a . When the lower arm  104   b  contacts the arm stopper  102   a , the recording medium  301  is sandwitched between the lower head  101   b  and the upper head  101   a . Then, the load state in which read and write procedure is possible is completed.  
         [0307]    Next, an explanation will be made for the operation in a case where the load state moves to the unload state and the lower head  101   b  is unloaded. FIG. 52 shows a perspective view of the head unload mechanism under the load state. In the figure, the frame  110  is not shown. Under the load state, the eject button  405  continues to be come out from the frame  110 .  
         [0308]    When the eject button  405  is pressed against the extension force caused by the coil spring  407  of the eject shaft  403 , the eject shaft  403  is moved. The rotating force receiver  402   c  being contacted to the lower face  403   d  under the load state slides on the taper face  403   b  when the eject shaft  403  slides and moves contacted portion to the higher face  403   c . When the rotating force receiver  402   c  moves from the lower face  403   d  to the higher face  403   c , the unload lever  402   b  rotates in the opposite direction of rotation shown by an arrow B when the unload state changes to the load state. According to the rotation of the unload lever  402   b , the lifter part  402   a  rotates. When the lifter part  402   a  contacts the lower arm  104   b , the lower arm  104   b  rotates in the direction of separating from the upper arm  104   a.    
         [0309]    Accordingly, both heads  101   a  and  101   b  are separated and the sandwich state of the recording medium  301  is released. After released, the recording medium cartridge  300  is ejected up to the position not to be contacted with the shaft barb stopper  408 . The shaft barb stopper  408  being bended on the side of the lower cover  113   b  becomes the unload state due to the elastic force. The convexity  408   a  engages with the barb stopper notch  403   e.    
       Embodiment 17  
       [0310]    In this embodiment, there is shown another embodiment related to the structure of the rotating force spring  404  and the outskirts structure.  
         [0311]    [0311]FIG. 53 shows a part of cross sectional side view of the rotating force receiver  402   c  which is fixed or unified in the unload lever  402   b.    
         [0312]    In the figure, an upper cover  113   a  covers the top face of the FDD unit  100 . A rotating force receiver  402   c  can rotate around the shaft center of the unload lever  402   b  as well as the unload lever  402   b  and the lifter part  402   a  not shown in the figure. A pressure foot  113   d,  wherein a part of the upper cover  113   a  is cut and pushed down, is situated on the top of the rotating force receiver  402   c.    
         [0313]    The pressure foot  113   d  gives a pressure to the rotating force receiver  402   c  so that the rotating force receiver  402   c  always contacts either of the higher face  403   c , the taper face  403   b  or the lower face  403   d  of the eject shaft  403 .  
         [0314]    Thus, by providing the pressure foot  113   d  on the upper cover  113   a , the rotating force spring  404  in Embodiment 16 and the tension receiver  402   d  do not need to be mounted and the number of components can be reduced.  
       Embodiment 18  
       [0315]    [0315]FIG. 54 shows a perspective view of the position setting mechanism for positioning the recording medium cartridge  300  on the FDD unit  100 . It shows an unload state where the position setting is released. FIG. 55 shows a perspective view of the position setting mechanism under the load state. FIG. 56 shows a perspective view of the engage state with the recording medium cartridge  300 .  
         [0316]    In the figures, a latch lever  410  is a position setting member for holding the load state which read and write procedure is possible in the FDD unit  100 . The latch lever is composed of the pole shaped stopper  410   a  and the almost U-shaped hook spring  410   b  in the plain of the cartridge receiving face  110   s.  The hook spring  410   b  is placed in a concave  110   p  of the frame  110 . When the recording medium cartridge  300  is loaded in the FDD unit  100 , the hook spring  410   b  is hidden under the recording medium cartridge  300  by the concave  110   p.    
         [0317]    The eject shaft  403  has a lock notch  403   f  to which the stopper  410   a  moves under the unload state. The lock notch  403   f  is provided to contact with the pole side of the stopper  410   a  of the latch lever. The stopper  410   a  is always forced to contact with the lock notch  403   f  by the hook spring  410   b.    
         [0318]    The side of the recording medium cartridge  300  has a semicircular stopper notch  300   a . When the recording medium cartridge  300  is completely inserted to the FDD unit  100 , the pole side of the stopper  410   a  is engaged with the stopper notch  300   a.    
         [0319]    Thus, the latch lever  410  is mounted to engage with the stopper notch  300   a  of the recording medium cartridge  300 . Accordingly, the position of the recording medium cartridge  300  both in the longish direction and the shortish direction is set.  
         [0320]    There is shown the operation of the cartridge position setting mechanism wherein the recording medium cartridge  300  is inserted to the FDD unit  100  changing the unload state to the load state.  
         [0321]    The recording medium cartridge  300  is inserted from the insertion and ejection port  180  and slides on the cartridge receiving face  110   s  so as to be inserted to the inside of the FDD unit  100 . In case of insertion, the latch lever  410  is placed on the side of the eject shaft  403  by the hook spring  410   b . Therefore, the latch lever contacts the lock notch  403   f.  This avoids bothering to insert the recording medium cartridge  300 . When the recording medium cartridge  300  is completely inserted, according to the unload mechanism of the read/write head  101 , the eject shaft  403  moves to the side of the insertion and ejection port  180 . At the same time, the lock notch  403   f  moves on the side of the insertion and ejection port  180 . The latch lever  410  being contacted the lock notch  403   f  moves out in the inside of the FDD unit  100  along the lock notch  403   f.  When the recording medium cartridge  300  is completely inserted and the movement of the eject shaft  403  finishes, the stopper  410   a  and the stopper notch  300   a  of the latch lever  410  are engaged and the recording medium cartridge  300  is set to the load state.  
         [0322]    There is shown the operation of the cartridge position setting mechanism wherein the recording medium cartridge  300  is ejected to the outside of the FDD unit  100  changing the load state to the unload state.  
         [0323]    The load state changes to the unload state according to the head unload mechanism. When the eject button  405  is pressed, the eject shaft  403  moves to the side of the insertion and ejection port  180 . The lock notch  403   f  also moves. According to the notched shape of the lock notch  403   f,  the latch lever  410  retracts in the direction of the eject shaft  403 . The engage state between the latch lever  410  and the stopper notch  300   a  is released. The recording medium cartridge  300  positioned in the inside of the FDD unit  100  by the latch lever  410  is released. As a result, the recording medium cartridge  300  is enabled to be ejected and the unload state is set. Based on such configuration, the recording medium cartridge  300  is positioned in the FDD unit  100 .  
       Embodiment 19  
       [0324]    This embodiment shows another embodiment related to the cartridge position setting mechanism.  
         [0325]    [0325]FIG. 57 shows a perspective view of the configuration of the cartridge position setting mechanism of the present embodiment. In the figure, a cartridge receiver face  110   s  is provided in the frame  110 . A side wall part  111   a is provided in the frame  110 . A lock notch  403     f  is provided in the eject shaft  403 . A latch lever  410  is composed of a pole shaped stopper  410   a  and a plate lever  410   c . The latch lever  410  is engaged with a pin  411 . The pin  411  is the stopper of the latch lever  410  in the direction of thickness of the FDD unit  100 . The pin  411  also serves as a rotation shaft so that the latch lever  410  can rotate.  
         [0326]    The latch lever  410  is not always forced to contact to the lock notch  403   f.  However, by the recording medium cartridge  300  being inserted, the inserting top of the recording medium cartridge  300  forces the stopper  410   a  to retract toward the lock notch  403   f . When the position setting mechanism enters the load state, the stopper  410   a  is pushed out from the lock notch  403   f  and is engaged with the stopper notch  300   a  of the recording medium cartridge  300 . When the recording medium cartridge  300  is ejected, with the ejecting operation of the recording medium cartridge  300 , the eject shaft  403  moves on the side of the insertion and ejection port  180 . The stopper  410   a  can be retracted in the inside of the lock notch  403   f . According to the movement of the recording medium cartridge  300 , the stopper  410   a  returns in the inside of the lock notch  403   f.    
       Embodiment 20  
       [0327]    [0327]FIG. 58 shows a part of cross sectional side view when the recording medium cartridge  300  is inserted to the FDD unit  100 . FIG. 59 shows a whole perspective view of the upper cover  113   a.    
         [0328]    In the upper cover  113   a , bend pieces  113   c  are provided. The bend pieces  113   c  press the recording medium cartridge  300  in the direction of thickness of the FDD unit  100  when the recording medium cartridge  300  is inserted to the FDD unit  100 . By an elasticity of the bend piece  113   c , the top face of the recording medium cartridge  300  is pressed down and therefore the recording medium cartridge  300  is firmly fixed in the FDD unit  100 .  
         [0329]    Thus, by pressing the recording medium cartridge  300  with the bend piece  113   c  of the upper cover  113   a , it is possible to perform stable read and write operation.  
         [0330]    As has been described, the unload lever rotates by moving the eject shaft and the head lifter contacts and rotates the arm according to the rotation of the unload lever. Accordingly, the recording medium cartridge can be inserted in the plane direction. The movement in the vertical direction is not needed. As a result, it is effective in that the structure can be simplified and the FDD unit can be made thinner.  
         [0331]    Since the eject spring whose one end on the side of the insertion and ejection port contacts the eject shaft and the other end contacts the frame, the eject shaft comes to be always forced toward the side of the insertion and ejection port. As a result, it is possible to simplify the mechanism related to the eject shaft and obtain the FDD unit at a low cost.  
         [0332]    Furthermore, the shaft barb stopper whose one end is engaged with the notch of the eject shaft and the other end is fixed on the frame is provided. When the recording medium cartridge is inserted and reaches to the position, the barb position of the shaft barb stopper is come down by the recording medium cartridge. Then, the engage state with the eject shaft is released and it is possible to move the eject shaft on the side of the insertion and ejection port. As a result, it is possible to make the FDD unit thinner.  
         [0333]    Since the touching part of the eject shaft contacting the unload lever has a taper shape and the unload lever rotates by moving the eject shaft, it is possible to simplify the head unload mechanism and obtain the FDD unit at a low cost.  
         [0334]    Since the unload lever whose one end contacts the unload lever and the other end contacts or fixed to the frame is provided, it is possible to simplify the head unload mechanism and obtain the FDD unit at a low cost.  
         [0335]    Since the pressure foot for giving the pressure to the unload lever in a predetermined direction is mounted, it is possible to simplify the head unload mechanism and obtain the FDD unit at a low cost.  
         [0336]    By moving the eject shaft, the latch lever is rotated or displaced. Accordingly, the latch lever can be engaged with the notch of the recording medium cartridge. Therefore, it is possible to determine the position of the recording medium cartridge and simplify the positioning mechanism of the recording medium cartridge. As a result, it is possible to obtain the FDD unit at a low cost.  
         [0337]    Since the bend piece for pressing the recording medium cartridge to the side of the recording medium drive actuator is provided on the cover, it is possible to pressure the recording medium cartridge and reduce the number of parts. As a result, it is possible to obtain the FDD unit at a low cost.  
       Embodiment 21  
       [0338]    Hereinafter, an embodiment according to this invention will be described with reference to the attached figures.  
         [0339]    [0339]FIG. 60 shows a plan view of the recording medium cartridge. FIG. 61 shows a side view of the cartridge.  
         [0340]    [0340]FIGS. 60 and 61 show a condition that a shutter  304  is opened. FIG. 62 shows a cross sectional view of the recording medium cartridge. FIG. 63 shows an A-A cross sectional view of FIG. 62 to the direction of the arrows.  
         [0341]    Further, FIG. 64 shows a part of a plan view of FDD unit according to the present invention. FIG. 65 shows a B-B cross sectional view of FIG. 64 to the direction of the arrows. FIG. 65 shows the FDD unit and the recording medium cartridge at the time when the recording medium is under the load state.  
         [0342]    A cartridge case  302  is composed of a resinous upper shell  302   a  and a resinous lower shell  302   b . The cartridge case  302  carries a disk shaped recording medium  301  fixed on the hub  303 . An opener band  306  is provided in the cartridge case  302 . The end of the opener band  306  is fixed to an opener latch  307  and the other end of the opener band  306  is fixed to a shutter  304 . As shown in FIG. 60, when the recording medium cartridge  300  is inserted into the FDD unit  100  in the X direction, the opener latch  307  is moved in the −X direction by the opener lever  324  mounted on the FDD unit  100 . Simultaneously, the shutter  304  is pulled in the −Y direction and the window  305  is opened. Then, the recording medium  301  is exposed. Here, an area S has no parts on no members of the cartridge case  302  and the shutter  304 . On the other hand, when the recording medium cartridge  300  is pulled out from the FDD unit  100 , the opener latch  307  is moved in the X direction by the opener lever  324 . Simultaneously, the shutter  304  is moved in the Y direction and a window  305  is closed.  
         [0343]    A slide member  310  is used to recognize the writing prohibition state wherein information once recorded in the recording medium  301  is not erased. A conductive metal piece  311  of yoked type is fixed on the slide member  310  based on such as an integral structure. The conductive metal piece  311  is composed of an elastic plate of a flat spring. The lower shell  302   b  fixes two conductive metal plates  312   a  and  312   b  separately as shown in FIGS. 62 and 63 based on such as an integral structure. Further, portions of the metal plates  312   a  and  312   b  are exposed under the lower shell  302   b.    
         [0344]    In FIGS. 64 and 65, a frame  110  supports the FDD unit. Terminals  115   a  and  115   b  are parts of a write protect switch which recognizes the writing prohibition state. Each of terminals  115   a  and  115   b  is composed of flat spring of the conductive metal. Each of the terminals  115   a  and  115   b  is fixed at the departed position not to be contacted to the other terminal by the switch holder  116 . The switch holder  116  is made of noncurrent substance like resin and fixed on the frame  110 .  
         [0345]    The ends of the terminals  115   a  and  115   b  are connected to the circuit board, not shown in the figure, in the FDD unit by the cable. When the recording medium cartridge  300  is mounted on the FDD unit  100  and the load state is set, terminals  115   a  and  115   b  are respectively contacted to the two metal plates  312   a  and  312   b  exposed from the lower shell  302   b.    
         [0346]    The operation of the write protect switch will now be described. FIG. 66 shows a cross sectional view in the direction of plan of the recording medium cartridge  300 . FIG. 66 shows a condition that the metal piece  311  fixed on the slide member  310  comes in contact with only metal plate  312   b  fixed on the lower shell  302   b . FIG. 67 shows a cross sectional view in the direction of plan of the recording medium cartridge  300 . The metal piece  311  shows a condition that the metal piece  311  contacts two metal plates  312   a  and  312   b.    
         [0347]    When the recording medium cartridge  300  is set under the load state in which read and write procedure is possible, write protect switch terminals  115   a  and  115   b  on the side of the FDD unit respectively contacts metal plates  312   a  and  312   b  fixed on the lower shell  302   b . As shown in FIG. 66, when the metal piece  311  contacts only the metal plate  312   b , the terminals  115   a  and  115   b  connected to the circuit board are not conducted. On the other hand, as shown in FIG. 67, in a case where the metal piece  311  contacts both of the metal plates  312   a  and  312   b , there occurs a conducting state between the terminals  115   a  and  115   b . The circuit board judges whether the writing is prohibited or not by checking the conducting state.  
         [0348]    In this way, when the part of the function of the write protect switch is provided in the recording medium cartridge  300 , a thinner type of FDD unit than a conventional one is configurated. It is possible to obtain the FDD unit  100  having thickness of below 5.0 mm, which is able to be inserted to the standard slot defined by the PCMCIA type specification.  
       Embodiment 22  
       [0349]    [0349]FIG. 68 shows a top view when the recording medium cartridge  300  is mounted on the FDD unit  100  under the load state in which read and write procedure is possible. FIG. 69 shows a side view of FIG. 68 and a C-C cross sectional view of FIG. 68 to the direction of an arrow.  
         [0350]    In the figures, an interface connector  181  is a connector in accordance with PCMCIA type 2 specification. A slide member  310  is used for recognizing writing prohibition state of the recording medium. A recording medium cartridge  300  is composed of the recording medium  301 , the upper shell  302   a , the lower shell  302   b , the slide member  310  and so on.  
         [0351]    When the recording medium cartridge  300  is mounted to the FDD unit  100  and the load state is set in which read and write procedure is possible, the slide member  310  is situated on the outside of the FDD unit  100 . In order to move the slide member  310  in the Y direction, the upper shell  302   a  has a hole to expose the slide member. Then, the slide member is moved through the hole. The center of the top of the recording medium cartridge  300  has another hole  300   h.  When the recording medium cartridge  300  is pulled out from the FDD unit  100 , the hole  300   h  can be used.  
         [0352]    When the slide member  310  used for recognizing the writing prohibition state of the recording medium is positioned on the outside of the FDD unit  100  and is facing to the top side to make the operation easy. Therefore, it is possible to set or reset the writing prohibition state unless the recording medium cartridge  300  is set to the unload state.  
       Embodiment 23  
       [0353]    [0353]FIG. 70 shows a cross sectional view in the direction of plan when the recording medium cartridge  300  is mounted on the FDD unit  100  in a case where the recording medium cartridge  300  is under the load state. FIG. 71 shows a D-D cross sectional view seen in the direction of the arrows.  
         [0354]    In the figures, a frame  110  supports the FDD unit  100 . A head drive actuator  105 , a circuit board  114  and a lower shell  302   b  are provided. The loading member  130  loads the recording medium cartridge  300  on the FDD unit and sets the position. A conductive metal plate  320  is used as a disk-in-switch for checking whether the recording medium cartridge  300  is mounted on the FDD unit  100  or not. A portion of the metal plate  320  is exposed and fixed on the surface of the lower shell  302   b  based on such as integral structure. Two disk-in-switch terminals  117  and  118  are fixed on the circuit board  114  by using such as a method of soldering.  
         [0355]    The disk-in-switch terminals  117  and  118  has a spring characteristic. The terminal end portions  117   a  and  118   a  are always pressed in the direction of top of the FDD unit, namely in the direction of thickness of the cartridge  300 . The terminal end portions  117   a  and  118   a  are arranged to get in touch with the exposed portion of the metal plate  320  fixed on the lower shell  302   b  when the recording medium cartridge  300  is mounted on the FDD unit  100  and the load state is set.  
         [0356]    When the recording medium cartridge  300  is mounted on the FDD unit  100 , both of the top portions  117   a  and  118   a  of the disk-in-switch terminals  117  and  118  come in contact with the metal plate  320  on the recording medium cartridge  300 . Then, the disk-in-switch terminals  117  and  118  becomes the conducting state. When the circuit board  114  detects the conducting state, it is possible to judge that the recording medium cartridge  300  has been under the load state in which read and write procedure is possible in the FDD unit  100 .  
         [0357]    Thus, the metal plate  320  is provided for the disk-in-switch at the bottom of the cartridge, namely, the lower shell  302   b . The portion of the metal plate is then exposed on the surface of the recording medium cartridge  300 . Further, by mounting the disk-in-switch terminals  117  and  118  from the circuit board  114 , the structure of the disk-in-switch for detecting that the recording medium cartridge  300  is under the load state on the FDD unit  100  is simplified and the FDD unit  100  can be made thinner.  
       Embodiment 24  
       [0358]    In this embodiment, there is shown another embodiment related to the structure of the disk-in-switch. FIG. 72 shows a cross sectional view in the direction of plan when the recording medium cartridge  300  is mounted on the FDD unit  100  and the load state is set. FIG. 73 shows an E-E cross sectional view of FIG. 72 seen in the direction of the arrows.  
         [0359]    In the figures, the frame  110  supports the FDD unit. The head drive actuator  105 , the circuit board  114  and the recording medium cartridge  300  are provided. The upper shell  302   a  is a top side case of the recording medium cartridge  300 . The slide member  310  is used for write protection. The shutter  304  is provided in the recording medium cartridge  300 . The interface connector  181  is the connector in accordance with PCMCIA type 2 specification.  
         [0360]    The circuit board  114  has a connector  331  having more than two (five in FIG. 72) terminals  332  to be a standard of position detecting when the recording medium cartridge  300  tries to be the load state. The recording medium cartridge  300  has a connector contact  330 . The connector contact  330  has a plurality of contacts to contact with each of the terminals  332 . So that there might be at least two conducting points, at least two contacts  330  are connected each other by using a method of soldering or a cable. FIG. 72 shows a conducting state between the contacts  330   a  and  330   b.    
         [0361]    According to the present embodiment, by detecting the conducting state based on the connection of the connectors and terminals, it is possible to detect the position of the recording medium cartridge  300  and obtain the stable thin disk-in-switch.  
       Embodiment 25  
       [0362]    [0362]FIG. 74 shows a top view of the recording medium cartridge  300 . In the figure, there is shown a condition that the shutter  304  is opened. FIG. 75 shows an F-F cross sectional view of FIG. 74 seen in the direction of the arrows.  
         [0363]    The recording medium  301  and the hub  303  are bonded by using such as a double coated pressure sensitive adhesive tape and carried in the recording medium cartridge  300  to be rotatable. A case of the recording medium cartridge  300  is composed of the upper shell  302   a  and the lower shell  302   b . The inside of the upper shell  302   a  corresponding to the position a little shifted from the center hole  303   a  of the hub  303  has an index sensor  340  to detect a predefined position in one rotation. The index censor  340  is a reflection type of photo sensor.  
         [0364]    The hub  303  is made of stainless material and its color is normally silver. So that a predefined position of the recording medium  301  or the hub  303  is detected by using a reflection type of photo sensor, a face  303   b  of the hub  303  facing to the index sensor  340  has a marker  350  of black color, for example, in order to be an opposite color of silver. As a result, when the recording medium  301  and the hub  303  rotate, the output signal of the index sensor  340  changes according to the black marker  350  on a part of the hub  303 . Then, it is possible to obtain the index signal from the changed signal.  
         [0365]    An index censor  340  is connected to a flexible print cable (hereinafter, referred to as FPC)  341 . Each contacts of the connector contact  330  at the connector socket  333  mounted on the side of the shutter  304  of the recording medium cartridge  300  are connected to FPC  341  by using a method of soldering and so forth. Accordingly, the index signal obtained by the index sensor  340  is output to the circuit board  114  of the FDD unit  100  through the FPC  341  and the connector contact  330 .  
         [0366]    Thus, by mounting the index censor  340  in the recording medium cartridge  300 , it is possible to make the FDD unit  100  smaller and thinner.  
       Embodiment 26  
       [0367]    This embodiment shows another embodiment of the recording medium cartridge described in Embodiment 25.  
         [0368]    [0368]FIG. 76 shows an F-F cross sectional view of FIG. 74 which is a top view of the recording medium cartridge, similar to the view of FIG. 75.  
         [0369]    In the figure, the upper shell  302   a , the lower shell  302   b , the hub  303  and the recording medium  301  are provided. The index sensor  340  uses the magnetic resistance device here. On the face  303   b  of the hub  303  facing to the index sensor  340 , a sheet magnet  351  which has N and S magnetic poles in the direction of plan is bonded by using adhesive and so on. As a result, when the recording medium  301  and the hub  303  rotate, the magnetic field of the magnet  351  fixed on a part of the hub  303  is detected by the magnetic resistance device of the index sensor  340 . Then, it is possible to obtain the index signal.  
         [0370]    Thus, by using the magnetic resistance device as the index sensor, it is possible to detect a predefined position in one rotation and to obtain the index signal as in Embodiment 25.  
       Embodiment 27  
       [0371]    [0371]FIG. 77 shows a plan view of the lower shell  302   b  of the recording medium cartridge  300 . FIG. 78 shows a part of the cross sectional plan view when the recording medium cartridge  300  is set under the load state where read and write procedure is possible in the FDD unit  100 . FIG. 79 shows a G-G cross sectional view of FIG. 78 seen in the direction of the arrows.  
         [0372]    In the figures, the lower shell  302   b , the shutter  304  and the recording medium  301  are provided. A part of a disk circumference of the recording medium  301  has a notch  301   a.  The lower shell  302   b  has a hole  300   b  to be able to inspect the notch  301   a.  In FIG. 77, the hole  300   b  is exposed only when the shutter  304  is opened. When the shutter  304  is shut, the hole  300   b  is covered by the shutter  304 . Therefore, the hole  300   b  is not seen from the surface of the recording medium cartridge  300 . However, the hole  300   b  does not need to locate at a place covered by the shutter  304 .  
         [0373]    In the FDD unit  100 , the index sensor  340  for detecting a predefined position in one rotation is mounted at a corresponding position the hole  300   b  of the lower shell  302   b  when the recording medium cartridge  300  is set under the load state where the read and write is possible. The index sensor  340  here uses the reflection type of photo sensor.  
         [0374]    There is shown a description of how the index signal is obtained by the index sensor  340 .  
         [0375]    When the recording medium cartridge  300  is set under the load state on the FDD unit  100 , the recording medium  301  is detected by the above mentioned disk-in-switch. Then, the recording medium drive actuator  140  rotates and simultaneously the recording medium  301  and the hub  303  rotates. Under the load state, since the position in which the index sensor  340  is mounted matches the position of the hole  300   b  placed on the lower shell  302   b , it is possible to detect the notch  301   a  of the recording medium  301  by the index sensor  340  using the reflection type of photo sensor. Thus, it is possible to obtain the index signal.  
         [0376]    By making the notch at the part of the circumference of the recording medium  301  and providing the index sensor  340  using a reflection type of photo sensor on the FDD unit  100 , it is possible to detect a predefined position in one rotation and to obtain the index signal. The mounting position of the index sensor does not need to be adjusted finely.  
         [0377]    As has been described, the medium exchange type storage unit has at least two metal plates in the recording medium cartridge and the slide member a fixed another metal piece. The writing prohibition state is judged whether the slide member gets in touch with one metal plate or both metal plates. It is possible to make the writing prohibition switch thinner.  
         [0378]    Since the conductive metal plate is exposed on the lower shell, it is possible to make the writing prohibition switch or make the disk-in-switch thinner.  
         [0379]    Since the slide member is placed at the outside upper surface exposed from the storage unit under the condition that the recording medium cartridge is mounted on the storage unit, it is possible to obtain the storage unit whose operation is easy.  
         [0380]    Furthermore, since the conductive metal plates are exposed on the surface of the recording medium cartridge and circuit board carried in the storage unit has conductive terminals of two poles, it is possible to make the disk-in-switch thinner.  
         [0381]    Furthermore, by mounting the part of the index sensor for detecting the predefined position in one rotation to the recording medium storage, it is possible to make the storage unit thinner.  
         [0382]    Furthermore, by mounting the reflection type of photo sensor for detecting a predefined position in one rotation in the recording medium in the recording medium cartridge, it is possible to obtain the storage unit providing a well qualified index signal.  
         [0383]    Furthermore, by mounting the magnetic resistance device for detecting a predefined position in one rotation of the recording medium, it is possible to obtain the storage unit providing a well qualified index signal.  
         [0384]    Furthermore, since a part of a circumference of the recording medium is partly notched, it is possible to obtain the index signal by the photo sensor and to obtain the storage unit whose reliability is high.  
         [0385]    Furthermore, by mounting the photo sensor in the vertical direction of the partly notched recording medium, it is possible to obtain the index signal and to obtain the storage unit whose quality is high.  
         [0386]    Having thus described several particular embodiments of the invention, various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only, and not intended to be limiting. The invention is limited only as defined in the following claims and the equivalents thereto.