Abstract:
A magnetic recording/reproducing apparatus is disclosed that is arranged to receive a tape cassette accommodating a tape recording medium that is selectively loaded thereto. The apparatus includes a rotating drum unit having a rotating head, and a loading mechanism that is configured to pull the tape recording medium of the loaded tape cassette out of the loaded tape cassette, wind the tape recording medium around the rotating drum unit, and form a tape path. The loading mechanism includes a short loading pole that is adapted for a first tape cassette accommodating a narrow tape recording medium and a long loading pole that is adapted for a second tape cassette accommodating a wide tape recording medium, which short pole and long pole are positioned at the same height, and a loading pole raising mechanism that is configured to raise the long loading pole when the second tape cassette is loaded.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to a magnetic recording/reproducing apparatus such as a streamer device that is used as a peripheral storage device of a computer. The present invention particularly relates to a magnetic recording/reproducing apparatus using a tape cassette and including a rotation drum and a tape loading mechanism, which magnetic recording/reproducing apparatus is capable of selectively loading a first tape cassette that accommodates a first magnetic tape having a first width W 1  or a second tape cassette that accommodates a second magnetic tape having a second width W 2  that is twice the first width W 1  of the first magnetic tape.  
         [0003]     2. Description of the Related Art  
         [0004]     As one type of magnetic recording/reproducing apparatus that is used as a peripheral storage device of a computer, a streamer device using a tape cassette and including a rotating drum and a tape loading mechanism like the VTR is being commercialized.  
         [0005]     The storage capacity of a conventional streamer device is relatively large at around 72 GB in compression mode, for example. Yet, there is a market demand for a streamer device with a larger storage capacity, and in turn, various manufacturers are developing new techniques for improving the streamer device.  
         [0006]     As one way of increasing the storage capacity of the streamer device, a new tape cassette that accommodates a magnetic tape having a tape width that is wider than the tape width of the magnetic tape of the conventional tape cassette may be used.  
       SUMMARY OF THE INVENTION  
       [0007]     In consideration of the fact that the conventional streamer device is still used and information is recorded on the conventional tape cassette by the conventional streamer device, it is an object of the present invention to provide a new streamer device that is capable of using a new tape cassette, is compatible with the conventional streamer device, is capable of using the conventional tape cassette, and is capable of accurately reproducing information recorded on the conventional tape cassette by the conventional streamer device.  
         [0008]     According to an aspect of the present invention, a magnetic recording/reproducing apparatus is provided that is arranged to receive a tape cassette accommodating a tape recording medium that is selectively loaded thereto, the loaded tape cassette being selected from a plurality of types of tape cassettes including a first tape cassette accommodating a first tape recording medium having a first width and a second tape cassette accommodating a second tape recording medium having a second width that is greater than the first width, the apparatus including:  
         [0009]     a rotating drum unit including a rotating head; and  
         [0010]     a loading mechanism that is configured to pull the tape recording medium of the loaded tape cassette out of the loaded tape cassette, wind the tape recording medium of the loaded tape cassette around the rotating drum unit, and form a tape path;  
         [0011]     wherein the loading mechanism includes  
         [0012]     a short loading pole that is adapted for the first tape cassette, and a long loading pole that is adapted for the second tape cassette, the short pole and the long pole being positioned at the same height; and  
         [0013]     a loading pole raising mechanism that is configured to raise the long loading pole when the second tape cassette is loaded.  
         [0014]     According to an aspect of the present invention, a long loading pole is arranged to be positioned at the same height as that of a short pole so that a first tape cassette accommodating a narrow tape recording medium may be suitably loaded without encountering any obstacles. When a second tape cassette accommodating a wide tape recording medium is loaded, the long loading pole may be raised to extend across and face the wide tape recording medium so that the wide tape recording medium may be stably pulled out without being damaged. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a diagram showing a conventional tape cassette, a new tape cassette, and a streamer device according to an embodiment of the present invention in perspective view;  
         [0016]      FIG. 2  is a diagram showing the streamer device of  FIG. 1  in plan view;  
         [0017]      FIG. 3  is a flowchart illustrating tape loading operations that are performed when the conventional tape cassette is loaded into the streamer device;  
         [0018]      FIG. 4  is a flowchart illustrating tape loading operations that are performed when the new tape cassette is loaded into the streamer device;  
         [0019]      FIG. 5  is a diagram showing the state of the streamer device after the tape loading operations for the conventional tape cassette are completed;  
         [0020]      FIG. 6  is a diagram showing the state of the streamer device after the tape loading operations for the new tape cassette are completed;  
         [0021]     FIGS.  7 A˜ 7 C are diagrams showing a 4 mm-width magnetic tape and an 8 mm-width magnetic tape that are wound onto a rotating drum unit, and track patterns that are formed on the magnetic tapes;  
         [0022]      FIGS. 8A and 8B  are diagrams illustrating the state of the streamer device when the conventional tape cassette is loaded;  
         [0023]      FIG. 9  is a diagram illustrating the state of the streamer device after a first operations step of  FIG. 3  is completed;  
         [0024]      FIG. 10  is a diagram illustrating the state of the streamer device after a second operations step of  FIG. 3  is completed;  
         [0025]      FIG. 11  is a diagram illustrating the state of the streamer device after a third operations step of  FIG. 3  is completed;  
         [0026]      FIGS. 12A and 12B  are diagrams illustrating the state of the streamer device when the new tape cassette is loaded;  
         [0027]      FIGS. 13A and 13B  are diagrams illustrating the state of the streamer device when a first operations step of  FIG. 4  is completed;  
         [0028]      FIG. 14  is a diagram illustrating the state of the streamer device after a second operations step of  FIG. 4  is completed;  
         [0029]      FIG. 15  is a diagram illustrating the state of the streamer device when a third operations step of  FIG. 4  is being performed;  
         [0030]      FIG. 16  is another diagram illustrating the state of the streamer device when the third operations step of  FIG. 4  is being performed;  
         [0031]      FIG. 17  is a diagram illustrating the state of the streamer device after the third operations step of  FIG. 4  is completed;  
         [0032]      FIG. 18  is a diagram illustrating the state of the streamer device after a fourth operations step of  FIG. 4  is completed;  
         [0033]      FIG. 19  is a downside perspective view of a first motion transmitting mechanism;  
         [0034]      FIG. 20  is a perspective view showing the initial state of a pole moving mechanism;  
         [0035]      FIG. 21  is a perspective view showing the state of the pole moving mechanism of  FIG. 20  when corresponding poles are moved;  
         [0036]      FIG. 22  is a perspective view of a second motion transmitting mechanism;  
         [0037]      FIG. 23  is a downside perspective view of the second motion transmitting mechanism;  
         [0038]      FIG. 24  is a plan view of the second motion transmitting mechanism;  
         [0039]     FIGS.  25 A˜ 25 C are diagrams illustrating motion transmission to a first drive gear that is performed in response to a clockwise rotation of an individual mode switching gear;  
         [0040]     FIGS.  26 A˜ 26 C are diagrams illustrating motion transmission to a second drive gear that is performed in response to a counter-clockwise rotation of the individual mode switching gear;  
         [0041]     FIGS.  27 A˜ 27 C are diagrams illustrating motion transmission to a third drive gear that is performed in response to a further counter-clockwise rotation of the individual mode switching gear;  
         [0042]      FIG. 28  is a perspective view showing the initial state of another pole moving mechanism;  
         [0043]      FIG. 29  is a perspective view showing the state of the pole moving mechanism of  FIG. 28  when corresponding poles are moved;  
         [0044]      FIG. 30  is a perspective view showing the initial state of a pole raising/lowering mechanism;  
         [0045]      FIG. 31  is a perspective view showing the state of the pole raising/lowering mechanism of  FIG. 30  when corresponding poles are raised;  
         [0046]      FIG. 32  is an enlarged view of one portion of the pole raising/lowering mechanism of  FIG. 30 ;  
         [0047]      FIG. 33  is an enlarged view of another portion of the pole raising/lowering mechanism of  FIG. 30 ;  
         [0048]      FIG. 34  is a perspective view showing the initial state of another pole moving mechanism; and  
         [0049]      FIG. 35  is a perspective view of the state of the pole moving mechanism of  FIG. 34  when corresponding poles are moved. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0050]     In the following, principles and embodiments of the present invention are described with reference to the accompanying drawings.  
         [0051]     Indicated below is a list of subjects to be discussed in the following description. 
    1. Outline of Streamer Device  30      2. Structures of Tape Cassettes  10  and  20      3. Outline of Tape Loading Operation     4. Tape Loading Operation for Conventional Tape Cassette  10      5. Tape Loading Operation for New Tape Cassette  20      6. Common Operations Mechanism     7. Common Operations     8. Individual Operations Mechanism     9. Individual Operations    
 
         [0061]     1. [Outline of Streamer Device  30 ] 
         [0062]      FIG. 1  is a diagram showing a structure of a streamer device  30  according to an embodiment of the present invention. In the following, overall functions and operations of the streamer device  30  are described.  
         [0063]      FIGS. 1 and 2  illustrate the state of the streamer device  30  before a tape cassette is loaded thereto. It is noted that in these drawings, directions X 1 -X 2  represent width directions, directions Y 1 -Y 2  represent length directions, and directions Z 1 -Z 2  represent height directions. The streamer device  30  is capable of selectively loading a conventional tape cassette  10  or a new tape cassette  20 , and is configured to record information on a magnetic tape  14  with a width of 4 mm as well as a magnetic tape  24  with a width of 8 mm. To realize such a configuration, a rotating drum unit  31  of the streamer device  30  according to the present embodiment has a greater diameter D and height H compared to a rotating drum unit provided in a conventional streamer device. Also, in the streamer device  30 , the winding angle for winding the magnetic tape with a width of 8 mm onto the rotating drum unit  31  is arranged to be greater than the winding angle for the magnetic tape with a width of 4 mm. As is shown in  FIG. 7A , the rotating drum  31  includes a lower stationary drum  31   a  and an upper rotating drum  31   b.  A rotating head is fixed to the bottom surface of the rotating drum  31   b,  and a tape guide  31   c  for guiding the bottom edge of the magnetic tape  14 / 24  onto the stationary drum  31   a  is provided.  
         [0064]     The streamer device  30  includes a cassette loading mechanism (not shown), the rotating drum unit  31  having plural rotating heads, a common operations motor  40 , a first motion transmitting mechanism  50  that transmits the rotation of the common operations motor  40 , an individual operations motor  60 , a second motion transmitting mechanism  70  that transmits the rotation of the individual operations motor  60  in a clockwise direction to a first part and transmits the rotation of the individual operations motor  60  in a counter-clockwise direction to a second part, a common operations motor drive circuit  80 , an individual operations motor drive circuit  81 , and a control circuit  82  including a microcomputer, for example. The cassette loading mechanism includes a housing that is adapted for the new tape cassette  20 , and is configured to be capable of selectively loading the conventional tape cassette  10  and the new tape cassette  20 . The rotating drum unit  31  is provided around a center region of the streamer device  30 , and is tilted toward the X 2  direction. The common operations motor  40  is provided at the X 1  side of the Y 1  side edge of the streamer device  30 . The individual operations motor  60  is provided at the X 2  side of the Y 1  side edge of the streamer device  30 . The first motion transmitting mechanism  50  is provided close to the common operations motor  40 , and the second motion transmitting unit  70  is provided close to the individual operations motor  60 . It is noted that according to the present embodiment, the motor is divided into the common operations motor  40  and the individual operations motor  60 , and the second motion transmitting mechanism  70  is configured to be able to switch the mechanism to which the rotation of the individual operations motor  60  is to be transmitted according to the rotation direction thereof. In this way, a single individual operations motor  60  may be sufficient for operating the two different types of tape cassettes  10  and  20 , and the size of the streamer device  30  may be miniaturized.  
         [0065]     The common operations motor  40  is driven when operating a common tape loading mechanism directed to both the magnetic tape  14  with a width of 4 mm and the magnetic tape  24  with a width of 8 mm. The rotation of the common operations motor  40  is transmitted to the common tape loading mechanism via the first motion transmitting mechanism  50  so that the common tape loading mechanism may be operated.  
         [0066]     The individual operations motor  60  is rotated in a clockwise direction upon operating a 4 mm-width magnetic tape loading mechanism directed to the magnetic tape  14  with a width of 4 mm. The individual operations motor  60  is rotated in a counter-clockwise direction upon operating an 8 mm-width magnetic tape loading mechanism directed to the magnetic tape  24  with a width of 8 mm. The rotation of the individual operations motor  60  in the clockwise direction is transmitted to the 4 mm-width magnetic tape loading mechanism via the second motion transmitting mechanism  50  so that the 4 mm-width magnetic tape loading mechanism may be operated. The rotation of the individual operations motor  60  in the counter-clockwise direction is transmitted to the 8 mm-width magnetic tape loading mechanism via the second motion transmitting mechanism  50  so that the 8 mm-width magnetic tape loading mechanism may be operated.  
         [0067]     The streamer device  30  also includes loading poles P 0 ˜P 9  (simply referred to as ‘pole’ hereinafter), a capstan  90 , a pinch roller  100 , and a head cleaner  110 . The poles P 0 , P 1 , P 2 , P 3 , and P 9  are commonly used by both the magnetic tapes with widths of 4 mm and 8 mm. The poles P 4 ( 4 ) and P 5 ( 4 ) are dedicated to the magnetic tape  14  with a width of 4 mm, and poles P 4 ( 8 ), P 5 ( 8 ), P 6 , P 7 , and P 8  are dedicated to the magnetic tape  24  with a width of 8 mm. It is noted that the numbers 4 and 8 in parentheses indicate the magnetic tape widths in millimeter units. The poles P 0 , P 1 , P 2 , P 3  realize the common tape loading mechanism, the poles P 4 ( 4 ) and P 5 ( 4 ) realize the 4 mm-width magnetic tape loading mechanism, and the poles P 4 ( 8 ), P 5 ( 8 ), P 6 , P 7 , and P 8  realize the 8 mm-width magnetic tape loading mechanism. As can be appreciated from the above descriptions, according to the present embodiment, a common tape loading mechanism that is commonly used by the magnetic tapes  14  and  24  with widths of 4 mm and 8 mm, respectively, is provided, and thereby, a number of poles may be commonly used by the magnetic tapes  14  and  24 . In this way, the number of poles may be reduced compared to the case of separately providing a tape loading mechanism dedicated to the magnetic tape  14  with a width of 4 mm, and a tape loading mechanism dedicated to the magnetic tape  24  with a width of 8 mm.  
         [0068]     Also, it is noted that the poles P 0 , P 2 , P 3 , P 6 , and P 7  correspond to stationary poles, and poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9  correspond to moving poles. The pole P 0  is positioned at the X 2  side of a tape cassette loading portion. The poles P 2  and P 3  are arranged such that their upper ends tilt toward each other to form a pair. The poles P 2  and P 3  are positioned at the entrance side of the rotating drum unit  31  with respect to the scanning direction of the magnetic tape, and are configured to provide a twist to the magnetic tape. The poles P 5  and P 6  are arranged such that their upper ends tilt away from each other to form a pair. The poles P 5  and P 6  are positioned at the exit side of the rotating drum unit  31  with respect to the scanning direction of the magnetic tape, and are configured to provide a twist to the magnetic tape. The capstan  90  is positioned at the X 1  side of the cassette loading portion. The pinch roller  100  is normally positioned at a high position, and is positioned close to the capstan  90 . The moving poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9  are arranged within the tape cassette loading portion in this order from the X 2  side to the X 1  side.  
         [0069]     Of the moving poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9 , the poles P 1 , P 4 ( 8 ), P 5 ( 8 ), P 8 , and P 9  are arranged to be longer than the poles P 4 ( 4 ) and P 5 ( 4 ). The longer poles P 1 , P 4 ( 8 ), P 5 ( 8 ), P 8 , and P 9  are lowered in the Z 2  direction with respect to the shorter poles P 4 ( 4 ) and P 5 ( 4 ) so that the heights of the top ends of the moving poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9  are arranged to be the same. As is described in detail below, according to this arrangement, the bottom edge of the conventional tape cassette  10  may be loaded at the same height as that of the new tape cassette  20  without interfering with the longer poles.  
         [0070]     2. [Structures of Tape Cassettes  10  and  20 ] 
         [0071]     In the following, the structures of the tape cassettes  10  and  20  are described with reference to  FIG. 1 .  
         [0072]     The conventional tape cassette  10  includes a cassette body  13  that is made of a box structure  11 , a front lid  12 , and a bottom slide board (not shown) which cassette body  13  accommodates the magnetic tape  14  that is wound onto a supply reel  15  and a winding reel  16 , and forms a tape path  17  along a rear surface of the lid  12 . Also, at the front side portion of the bottom surface of the cassette body  13 , a pole accommodating space  18  that is opened upon loading the tape cassette  10  is provided. The new tape cassette  20  includes a cassette body  23  that is made of a box structure  21 , a front lid  22 , and a bottom slide board (not shown) which cassette body  23  accommodates the magnetic tape  24  that is wound onto a supply reel  25  and a winding reel  26 , and forms a tape path  27  along a rear surface of the lid  22 . Also, at the front side portion of the bottom surface of the cassette body  23 , a pole accommodating space  28  that is opened upon loading the tape cassette  20  is provided. It is noted that the new tape cassette  20  is arranged to have the same length A and width B dimensions as the conventional tape cassette  10 . The height C of the new tape cassette  20  is arranged to be 1.5 times the height C of the conventional tape cassette  10 . Also, it is noted that a recessed portion  29  is formed at the rear edge middle portion of the bottom surface of the box structure  21  of the new tape cassette  20 .  
         [0073]     The portion of the streamer device  30  to which the conventional tape cassette  10  and the new tape cassette  20  are loaded includes a supply reel axle unit  32 , a winding axis unit  33 , and a tape cassette identifying switch  34 . The tape cassette loading mechanisms are arranged such that the height position of the bottom surface of the new tape cassette  20  upon being loaded corresponds to the loaded height position of the bottom surface of the conventional tape cassette  10 .  
         [0074]     3. [Outline of Tape Loading Operations] 
         [0075]     In the following, an overall description of tape loading operations of the streamer device  30  is given.  
         [0076]     Referring to  FIG. 3 , when the conventional tape cassette  10  is loaded, a conventional tape cassette recognition operation  120 , poles P 1  and P 9  moving operations  121 , poles P 4 ( 4 ) and P 5 ( 4 ) moving operations  122 , a pinch roller moving operation  123 , and a head cleaner moving operation  124  are performed in this order.  
         [0077]     Referring to  FIG. 4 , when the new tape cassette  20  is loaded, a new tape cassette recognition operation  130 , poles P 1 , P 5 ( 8 ), P 8 , and P 9  raising operations  131 , poles P 1  and P 9  moving operations  132 , poles P 5 ( 8 ), P 8 , and P 4 ( 8 ) moving operations  133 , a pinch roller moving operation  134 , and a head cleaner moving operation  135  are performed in this order.  
         [0078]     The poles P 1  and P 9  moving operations  121  and  132 , the pinch roller moving operations  123  and  134 , and the head cleaner moving operations  124  and  135  correspond to common operations, and are realized by rotating the common operations motor  40  in a clockwise direction.  
         [0079]     The poles P 4 ( 4 ) and P 5 ( 4 ) moving operations  121  correspond to operations unique to the conventional tape cassette  10 . The poles P 1 , P 5 ( 8 ), P 8 , and P 9  raising operations  131 , and the poles P 5 ( 8 ), P 8 , and P 4 ( 8 ) moving operations  133  correspond to operations unique to the new tape cassette  20 . These operations are realized by rotating the individual operations motor  50 . Specifically, the operations  122  that are unique to the conventional tape cassette  10  are realized by rotating the individual operations motor  50  in a counter-clockwise direction, and the operations  131  and  133  that are unique to the new tape cassette  20  are realized by rotating the individual operations motor  50  in a clockwise direction. It is noted that the circular marks in  FIGS. 3 and 4  indicate the motor that is driven and the rotating direction of the operating motor in each of the operations  121 ˜ 124  and  131 ˜ 135 .  
         [0080]      FIGS. 5 and 11  are diagrams illustrating the state of the streamer device  30  after the conventional tape cassette  10  is loaded into the streamer device  30  and the tape loading operations  121 ,  122 , and  123  of  FIG. 3  are performed. As is shown in the drawings, the magnetic tape  14  forms a tape path  17 - 2  (see  FIG. 11 ). Also, as is shown in conjunction with  FIG. 7A , the magnetic tape  14  is guided by the tape guide  31   c  to be wound onto the rotating drum unit  31  over a winding angle α 1  from a start position S to an end position E 1  (e.g., around 90 degrees) in a diagonal direction, and as is shown in  FIG. 7B , a rotating head scans the magnetic tape  14  in a direction indicated by arrow  162  so that information may be recorded on the magnetic tape  14  in the form of a track pattern  160  with angle θ. It is noted that the track pattern  160  corresponds to a track pattern with lower compatibility that is identical to the type of track pattern formed by a conventional streamer device.  FIG. 7B  shows the opposite side of the magnetic film surface of the magnetic tape  14 ; that is, the Y 2  side of the magnetic tape  14 . The angle α 1  corresponds to an angle range required for forming the track pattern  160  across substantially the entire width of the magnetic tape  14 . The arrow  162  indicates the direction in which the rotating head scans the magnetic tape  14 .  
         [0081]      FIGS. 6 and 18  illustrate the state of the streamer device  30  after the new tape cassette  20  is loaded and the tape loading operations  131 ,  132 ,  133 , and  134  of  FIG. 4  are performed. As is shown in the drawings, the magnetic tape  24  forms a tape path  27 - 4  (see  FIG. 18 ). Also, as is shown in conjunction with  FIG. 7A , the magnetic tape  24  is guided by the tape guide  31   c  to be wound onto the rotating drum unit  31  over a winding angel α 2  from a start position S to an end position E 2  (e.g., around 180 degrees) in a diagonal direction, and as is shown in  FIG. 7C , the rotating head scans the magnetic tape  24  in a direction indicated by arrow  163  to record information on the magnetic tape  24  in the form of a track pattern  161  with angle θ. The track pattern  161  corresponds to an extended track pattern of the track pattern  160 , and in this way, the recording capacity of the new tape cassette  20  is increased with respect to that of the conventional tape cassette  10 . It is noted that  FIG. 7C  shows the opposite side of a magnetic film surface of the magnetic tape  24 . The angle α 2  corresponds to an angle range required for forming the track pattern  161  across substantially the entire width of the magnetic tape  24 . The direction of arrow  163  shown in  FIG. 7C  corresponds to the direction of arrow  162  shown in  FIG. 7B .  
         [0082]     It is noted that the winding start position S for winding the magnetic tape  14  onto the rotating drum unit  31  and the winding start position S for winding the magnetic tape  24  onto the rotating drum unit  31  correspond to the same position.  
         [0083]     4. [Tape Loading Operations for Conventional Tape Cassette  10 ] 
         [0084]     In the following, tape loading operations performed in a case where the conventional tape cassette  10  is loaded are described with reference to  FIGS. 8 through 11 .  
         [0085]     Referring to  FIG. 2 , it is noted that the streamer device  30  includes paths  140 ˜ 145  through which the corresponding poles may move, and stoppers  151 ,  152 , and  154 .  
         [0086]      FIGS. 8A and 8B  illustrate the state of the streamer device  30  when the conventional tape cassette  10  is loaded thereto. As is shown in  FIG. 8B , the bottom surface of the conventional tape cassette  10  is set to height H 10  upon being loaded. When the conventional tape cassette  10  is loaded, the slide board (not shown) is slid, the supply reel  15  and the winding reel  16  are engaged by the supply reel axle unit  32  and the winding reel axle unit  33 , respectively, the lid  12  is opened, and the poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9  enter the pole accommodating space  18 . The tape cassette identifying switch  32  is pushed by the cassette body  13 , and the conventional cassette recognition operation  120  is performed.  
         [0087]     In response to the conventional cassette recognition operation  120 , first, as is shown in  FIG. 9 , the poles P 1  and P 9  moving operations  121  are performed. In  FIG. 9 , the common operations motor  40  is rotated in a clockwise direction to operate the first motion transmitting mechanism  50 . Accordingly, the pole P 1  is moved toward the X 2  direction, the pole P 9  is moved toward the X 1  direction, and the magnetic tape  14  is pulled out of the tape cassette  10  to form a first tape path  17 - 1 .  
         [0088]     Then, as is shown in  FIG. 10 , the poles P 4 ( 4 ) and P 5 ( 4 ) moving operations  122  are performed. In  FIG. 10 , the individual operations motor  60  is rotated in a clockwise direction to operate the second motion transmitting mechanism  70 . Accordingly, the pole P 4 ( 4 ) engages a guide rail portion  147  at the X 2  side of the path  141  (see  FIG. 28 ), and moves along the path  141  toward the Y 1  direction until reaching the stopper  151 . The pole P 5 ( 4 ) is moved along the path  144  toward the Y 1  direction until reaching stopper  154 . Then, the poles P 4 ( 4 ) and P 5 ( 4 ) pull the magnetic tape  14  further to extend the tape path  17 - 1 . In turn, the magnetic tape  14  is wound around the rotating drum unit  31  over an angle α 1  from the position S to the position E 1  in a diagonal direction, and comes into contact with the capstan  90  to form a second tape path  17 - 2 . It is noted that the pole P 5 ( 4 ) and the magnetic tape  14  pass on the Z 2  side of the pinch roller  100  so as to avoid interfering with the pinch roller  100 .  
         [0089]     In the second tape path  17 - 2 , the magnetic tape  14  extends from the supply reel  15  of the conventional tape cassette  10 , is guided by the poles P 0  and P 1 , is guided and twisted by the poles P 2  and P 3 , is wound onto the rotating drum unit  31  between the poles P 4 ( 4 ) and P 5 ( 4 ), and is guided by the capstan  90  and the pole P 9  to enter the winding reel  16  of the conventional tape cassette  10 .  
         [0090]     Then, as is shown in  FIG. 11 , the pinch roller moving operation  123  is performed. In  FIG. 11 , the common operations motor  40  is rotated in a clockwise direction to operate the first motion transmitting mechanism  50 . Accordingly, the pinch roller  100  is moved downward toward the Z 2  direction and enters the second tape path  17 - 2 . Then, the pinch roller  100  is moved in the Xl direction to be pushed toward the capstan  90 , and the magnetic tape  14  starts running in a direction indicated by arrow  139  so that an information recording or reproducing operation may be started.  
         [0091]     It is noted that in the illustrated embodiment, the magnetic tape  14  is wound onto the rotating drum unit  31  until reaching the winding end position E 1 . The magnetic tape  14  is separated from the peripheral surface of the rotating drum unit  31  immediately before the rotating head scanning the magnetic tape  14  in a diagonal direction reaches the top edge of the magnetic tape  14 . Such an arrangement prevents the rotating head from scanning across the top edge of the magnetic tape  14 , and thereby, prevents damage of the magnetic tape  14  resulting from the rotating head scanning across the top edge of the magnetic tape  14 .  
         [0092]     Then, the head cleaner moving operation  124  is performed. As is shown in  FIG. 11 , the common operations motor  40  is rotated in a clockwise direction to operate the first motion transmitting mechanism  50 . Accordingly, the head cleaner  110  is moved to a position indicated by a two-dotted line in the drawing to come into contact with the rotating drum unit  31 , and the rotating head is thus cleaned.  
         [0093]     It is noted that tape unloading operations are realized by performing the above-described operations in reverse order, in each of which operations the components being moved are moved in reverse directions with respect to the moving directions indicated above.  
         [0094]     5. [Tape Loading Operations for New Tape Cassette  20 ] 
         [0095]     In the following, tape loading operations that are performed in a case where the new tape cassette  20  is loaded into the streamer device  30  are described with reference to  FIGS. 12 through 18 .  
         [0096]      FIGS. 12A and 12B  illustrate the state of the streamer device  30  when the new tape cassette  20  is loaded thereto. As is shown in  FIG. 12B , the bottom surface of the new tape cassette  20  is set to height H 10  upon being loaded. When the new tape cassette  20  is loaded, the slide board (not shown) is slid, the supply reel  25  and the winding reel  26  are engaged by the supply reel axle unit  32  and the winding reel axle unit  33 , respectively, the lid  22  is opened, and the poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9  enter the pole accommodating space  28 . In this case, the recessed portion  29  is arranged to face against the tape cassette identifying switch  32  so that the tape identifying switch  32  is not pushed, and thus, the new cassette recognition operation  130  is performed. Also, it is noted that when the new tape cassette  20  is loaded, the bottom edge of the magnetic tape  24  is positioned at height H 11 , which corresponds to the loaded height position of the bottom edge of the magnetic tape  14  of the conventional tape cassette  10 .  
         [0097]     In response to the new cassette recognition operation  130 , first, as is shown in  FIGS. 13A and 13B , the poles P 1 , P 5 ( 8 ), P 8 , and P 9  raising operations  131  are performed. In  FIGS. 13A and 13B , the individual operations motor  60  is rotated in a counter-clockwise direction so that the second motion transmitting mechanism  70  is operated. Accordingly, a pole raising/lowering mechanism  280  and other related components (see  FIG. 30 ) are operated so that the poles P 1 , P 5  ( 8 ), P 8 , and P 9  may be raised in the Z 1  direction within the pole accommodating space  28  to span across substantially the entire width of the 8 mm-width magnetic tape  24 . It is noted that when the poles are not arranged to face against the entire width of the magnetic tape  24  upon engaging with the magnetic tape  24  to pull the magnetic tape  24  out of the new tape cassette  20 , the engagement between the poles and the magnetic tape  24  may be unstable to thereby cause damage to the magnetic tape  24 . On the other hand, when the poles P 1 , P 5  ( 8 ), P 8 , and P 9  are arranged to face against the entire width of the 8 mm-width magnetic tape  24 , the magnetic tape  24  may be engaged without causing damage thereto.  
         [0098]     It is noted that the upper ends of the moving poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9  are arranged to be positioned at the same height, and the longer poles P 1 , P 4 ( 8 ), P 5 ( 8 ), P 8 , and P 9  are normally set to lowered positions (in the Z 2  direction) so that the conventional tape cassette  10  may be loaded at the same height as the loading height position of the new tape cassette  20  without interfering with the longer poles P 1 , P 4 ( 8 ), P 5  ( 8 ), P 8 , and P 9 . Accordingly the operations  131  are performed when the new tape cassette  20  is loaded into the streamer device  30  so as to adjust the heights of the poles for use in the new tape cassette loading operations.  
         [0099]     Then, as is shown in  FIG. 14 , the poles P 1  and P 9  moving operations  132  are performed. In  FIG. 14 , the common operations motor  40  is rotated in a clockwise direction to operate the first motion transmitting mechanism  50 . Accordingly, the pole P 1  is moved toward the X 2  direction, the pole P 9  is moved toward the X 1  direction, and the magnetic tape  24  is pulled out of the tape cassette  20  to form a first tape path  27 - 1 .  
         [0100]     Then, the P 5 ( 8 ), P 8 , and P 4 ( 8 ) moving operations are performed. First, as is shown in  FIG. 15 , the individual operations motor  60  is rotated in a counter-clockwise direction to operate the second motion transmitting mechanism  70 . Accordingly, the poles P 5 ( 8 ) and P 8  are moved toward the Y 1  direction along paths  142  and  143 , respectively, to pull out the magnetic tape  24  further. In turn, the first tape path  27 - 1  is extended so that the magnetic tape  24  comes into contact with the rotating drum unit  31  to form a second tape path  27 - 2 . Then, as is shown in  FIG. 16 , after a certain delay, the pole P 4 ( 8 ) is moved toward the Y 1  direction. The pole P 4 ( 8 ) engages a guide rail portion  146  at the X 1  side of path  141  to be moved along this guide rail portion  146  toward the Y 1  direction. The guide rail portion  146  includes a sloped portion  146 a sloping in the Z 1  direction, and the pole P 4 ( 8 ) is raised in the Z 1  direction while being moved toward the Y 1  direction to be arranged at a height corresponding to the width of the magnetic tape  24 . The pole P 4 ( 8 ) moves toward the Y 1  direction to engage the magnetic tape  24 , and continues moving with the magnetic tape  24  engaged thereto.  
         [0101]     In the following, the reason for delaying the start of the operation for moving the pole P 4 ( 8 ) is explained. First, in order to reduce the size of the streamer device  30 , a dedicated path is not provided for the pole P 4 ( 8 ), and the pole P 4 ( 8 ) uses the path  141 , which is also used by the pole P 4 ( 4 ). Second, in this respect, the pole P 4 ( 8 ) is arranged to be raised while being moved. Third, the magnetic tape  24  is preferably distanced as far away (in the Y 1  direction) as possible from the new tape cassette  20  so that the pole P 4 ( 8 ) may be completely raised before reaching the magnetic tape  24 .  
         [0102]     As is shown in  FIG. 17 , the poles P 4 ( 8 ), P 5 ( 8 ), and P 8  reach the stoppers  151 ,  152 , and  153 , respectively, at substantially the same time. The second tape path  27 - 2  is further extended to form a third tape path  27 - 3  as is shown in  FIG. 16 , which third tape path  27 - 3  is further extended so that the magnetic tape  24  is wound around the rotating drum unit  31  over a winding angle α 2  from the start position S to the end position E 2  in a diagonal direction and comes into contact with the capstan  90  to form a fourth tape path  27 - 4  as is shown in  FIG. 17 . It is noted that the pole P 8  and the magnetic tape  24  pass the Z 2  side of the pinch roller  100  without interfering with the pinch roller  100 .  
         [0103]     In the fourth tape path  27 - 4 , the magnetic tape  24  extends from the supply reel  25  side of the new tape cassette  20 , is guided by the poles P 0  and P 1 , is guided and twisted by the poles P 2  and P 3 , is wound onto the rotating drum unit  31  between the poles P 4 ( 8 ) and P 5 ( 8 ), is guided and twisted by the poles P 6  and P 7 , and is guided by the pole P 8 , the capstan  90 , and the pole P 9 , to then enter the winding reel  26  of the new tape cassette  20 .  
         [0104]     Then, as is shown in  FIG. 18 , the pinch roller moving operation  134  is performed. In  FIG. 18 , the common operations motor  40  is rotated in a clockwise direction to operate the first motion transmitting mechanism  50 . Accordingly, the pinch roller  100  is moved downward toward the Z 2  direction and enters the fourth tape path  27 - 4 . Then, the pinch roller  100  is moved in the X 1  direction to be pushed toward the capstan  90 , and the magnetic tape  24  starts running in the direction indicated by arrow  139  so that an information recording or reproducing operation may be started.  
         [0105]     It is noted that in the illustrated embodiment, the magnetic tape  24  is wound onto the rotating drum unit  31  until reaching the winding end position E 2 . The magnetic tape  24  is separated from the peripheral surface of the rotating drum unit  31  immediately before the rotating head scanning the magnetic tape  24  in a diagonal direction reaches the top edge of the magnetic tape  24 . Such an arrangement prevents the rotating head from scanning across the top edge of the magnetic tape  24 , and thereby prevents damage of the magnetic tape  24  resulting from the rotating head scanning across the top edge of the magnetic tape  24 .  
         [0106]     Then, the head cleaner moving operation  135  is performed. As is shown in  FIG. 18 , the common operations motor  40  is rotated in a clockwise direction to operate the first motion transmitting mechanism  50 . Accordingly, the head cleaner  110  is moved to a position indicated by a two-dotted line in the drawing to come into contact with the rotating drum unit  31 , and the rotating head is thus cleaned.  
         [0107]     It is noted that tape unloading operations are realized by performing the above-described operations in reverse order, in each of which operations the components being moved are moved in reverse directions with respect to the moving directions indicated above.  
         [0108]     Also, it is noted that in the illustrated embodiment, the magnetic tape  14 / 24  is twisted by the stationary poles P 2  and P 3  before being wound onto the rotating drum unit  31 , and the perpendicular pole P 4 ( 4 / 8 ) moves to pull out the magnetic tape  14 / 24  and position the magnetic tape  14 / 24  alongside the rotating drum unit  31  and determines the position of the magnetic tape  14 / 24  at the entrance side of the rotating drum unit  31 . Also, the magnetic tape  14 / 24  is twisted by the stationary poles P 6  and P 7  after separating from the rotating drum unit  31 , and the pole P 5 ( 4 / 8 ) moves to pull out the magnetic tape  14 / 24  and determines the position of the magnetic tape  14 / 24  at the exit side of the rotating drum unit  31 . By realizing such an arrangement, the moving poles P 1 , P 4 ( 4 ), P 4 ( 8 ), P 5 ( 8 ), P 8 , P 5 ( 4 ), and P 9  may be accommodated within the pole accommodating space  18 / 28 .  
         [0109]     6. [Common Operations Mechanism] 
         [0110]     In the following, the common operations motor  40 , the first motion transmitting mechanism  50 , and operations and mechanisms that are controlled by the power transmitted from the first motion transmission mechanism  50  are described.  
         [0111]      FIG. 19  illustrates the state of the first motion transmitting mechanism  50  when the streamer device  30  is in the state as is illustrated by  FIG. 1  (i.e., when a tape cassette is not loaded).  FIG. 19  is a downside perspective view of the first motion transmitting mechanism  50 . According to this drawing, the first motion transmitting mechanism  50  includes an operation state detection substrate  170  that is provided with plural photo detectors, and a common mode switching gear  171  that has a mode switching pattern formed on its lower surface and a cam  172  provided on its upper surface. The operation state detection substrate  170  optically detects a rotation angle position of the common mode switching gear  171  based on the combination of outputs from the photo detectors, and detects the operation state of the first motion transmitting mechanism  50 . In turn, as is shown in  FIG. 2 , a detection signal is transmitted from the operation state detection substrate  170  to a control circuit  82 , and a control signal is transmitted from the control circuit  82  to a motor drive circuit  80  so that the motor drive circuit  80  may be operated. In turn, the common operations motor  40  is activated and deactivated at predetermined timings to perform the poles P 1  and P 9  moving operations  121 ,  131 , the pinch roller moving operations  123 ,  134  and the head cleaner moving operations  124 ,  135  of  FIGS. 3 and 4 . The first motion transmitting mechanism  50  also includes a tape cassette loading arm  173  that is rotated by the cam unit  172  and is configured to operate a tape cassette loading mechanism (not shown). It is noted that in the illustrated embodiment, the common mode switching gear itself is provided with a mode switching function, and in this way, the mode position may be accurately determined compared to an arrangement in which the mode switching function is provided elsewhere.  
         [0112]     7. [Common Operations] 
         [0113]     [Poles P 1  and P 9  Moving Operations  121 / 131 ] (see  FIGS. 20 and 21 )  
         [0114]      FIGS. 20 and 21  are diagrams showing states of a pole moving mechanism for the poles P 1  and P 9 .  
         [0115]     As is shown in  FIGS. 20 and 21 , the pole P 1  is fixed to the tip portion of arm  181 . A sleeve  182  is fixed to the base portion of the arm  181 , and this sleeve  182  is rotatably and slidably engaged and supported by a stationary post  186  (see  FIG. 30 ) that is fixed to a chassis base. A sleeve  185  is fixed to the base portion of the arm  183 , and this sleeve  185  is rotatably and slidably engaged and supported by a stationary post  187  (see  FIG. 30 ) that is fixed to the chassis base.  
         [0116]     When the common operations motor  40  is driven, a gear mechanism  174  is driven via a worm gear  41  (see  FIG. 19 ), a drive gear  175  is rotated in a clockwise direction (see  FIG. 20 ), a slide lever  176  is slid in the Y 2  direction, and a slide lever  180  is slid in the Y 2  direction via a rotating lever  177 , a link  178 , and a rotating lever  179  (see  FIG. 21 ). In response to the sliding motion of the slide lever  180 , the arm  181  is rotated in a counter-clockwise direction around the stationary post  186  and the pole P 1  is thus moved. Also, in response to the sliding motion of the slide lever  176 , the arms  184  and  183  are rotated in a clockwise direction around the stationary post  187  and the pole P 9  is thus moved.  
         [0117]     [Pinch Roller Moving Operation  123 / 134 ] (see  FIG. 19 )  
         [0118]     When the common operations motor  40  is driven, a cylinder portion  102  at the base of a pinch roller support arm  101  is guided by a perpendicular trench to be lowered in the Z 2  direction, and upon reaching the end of the perpendicular trench, the pinch roller support arm  101  is rotated in a direction indicated by arrow  193 . In this way, the pinch roller  100  is pushed toward the capstan  90 .  
         [0119]     [Head Cleaner Moving Operation  124 / 135 ] (see  FIG. 19 )  
         [0120]     When the common operations motor  40  is driven, the common mode switching gear  171  is rotated, and an arm member  111  is rotated by the cam  172  that is provided at the common mode switching gear  171  so that the head cleaner  110  is moved to come into contact with the rotating drum unit  31 .  
         [0121]     It is noted that after the common mode switching gear  171  is rotated and the head cleaner  110  is moved accordingly, the common mode switching gear  171  may be rotated in a reverse direction, and the above described operations may be performed in reverse order (i.e.,  124 / 135 ,  123 / 134 ,  121 / 131 ) in which case the components moved in each operation are moved in reverse directions with respect to the moving directions indicated above. In this way, the mechanisms described above may be set back to their initial states.  
         [0122]     8. [Individual Operations Mechanism] 
         [0123]     In the following, the individual operations motor  60 , the second motion transmitting mechanism  70 , and operations and mechanisms controlled by the power transmitted from the second motion transmitting mechanism are described.  
         [0124]      FIGS. 22, 23 , and  24  illustrate the second motion transmitting mechanism  70  of the streamer device  30 .  FIG. 22  is a perspective view of the second motion transmitting mechanism  70  from the upper side,  FIG. 23  is a perspective view of the second motion transmitting mechanism  70  from the lower side, and  FIG. 24  is a diagram showing the state of the second motion transmitting mechanism  70  when the streamer device  30  is in the state as is shown in  FIG. 1 , such a state being referred to as initial state hereinafter. It is noted that  FIG. 22  shows the state of the second motion transmitting mechanism  70  after the poles P 1 , P 5 ( 8 ), P 8 , and P 9  moving operations  131  are completed.  
         [0125]     As is shown in  FIGS. 22, 23 , and  24 , the second motion transmitting mechanism  70  includes an individual mode switching gear  200 , a first drive gear  210 , a second drive gear  220 , a third drive gear  230 , and an operation state detection substrate  240 . The mode switching gear  200  is provided at the Z 2  side of the common mode switching gear  171  and is arranged to be coaxial with the common mode switching gear  171 . The first, second, and third drive gears  210 ,  220 , and  230  are provided in the vicinity of the individual mode switching gear  200 , and as is described in detail below, these drive gears  210 ,  220 , and  230  are arranged to be temporarily driven at different timings in response to the rotation of the individual mode switching gear  200 . It is noted that a mode switching pattern  209  is formed at the lower surface of the individual mode switching gear  200 , and the operation state detection substrate  204  includes plural photo detectors. The operation state detection substrate  204  optically detects the rotation angle position of the individual mode switching gear  200  based on the combination of outputs from the photo detectors to detect the operation state of the second motion transmitting mechanism  70 .  
         [0126]     As is shown in  FIG. 2 , a detection signal is transmitted from the operation state detection substrate  240  to the control circuit  82 , and a control signal is transmitted from the control circuit  82  to the motor drive circuit  81 . Accordingly, the motor drive circuit  81  is operated and the individual operations motor  60  is activated and deactivated at predetermined timings to realize the poles P 4 ( 4 ) and P 5 ( 4 ) moving operations  122  of  FIG. 3 , the poles P 1 , P 5 ( 8 ), and P 9  raising operations  131 , and the poles P 5 ( 8 ), P 8 , and P 4 ( 8 ) moving operations  133  of  FIG. 4 . It is noted that in the illustrated embodiment, the individual mode switching gear itself is provided with a mode switching function, and thereby, the mode position may be accurately determined compared to an arrangement in which the mode switching function is provided elsewhere.  
         [0127]     The individual mode switching gear  200  includes a gear portion  201 , a recessed portion  202 , and an arc-shaped recessed portion  203 . Also, a partial gear portion  205  and a cam portion  206  are provided on the surface of the individual mode switching gear  200  to form a stepped arrangement. The recessed portion  202  and the arc-shaped recessed portion  203  are formed by cutting a Z 2 -side half section of the gear portion  201 . The recessed portion  202  and the arc-shaped recessed portion  203  are positioned next to each other with a protruding portion  207  provided therebetween. The arc-shaped recessed portion  203  extends over an angle of approximately  120  degrees. The gear portion  201  includes a full-length gear portion  201   a  and a half-length gear portion  201   b.  The cam portion  206  includes a recessed portion  206 a, an arc-shaped recessed portion  206   b,  and a pin portion  206   c  provided next to the recessed portion  206   a.    
         [0128]     The first drive gear  210  includes a partial gear portion  211  and a protruding portion  212  at one end of the partial gear portion  211 . In the initial state, the partial gear portion  211  is not engaged with the partial gear portion  205 . The first drive gear  210  may be rotated by a predetermined angle to realize the poles P 4 ( 4 ) and P 5 ( 4 ) moving operations  122 .  
         [0129]     The second drive gear  220  includes three protruding portions  221 ,  222 , and  223 . Also, an arc-shaped recessed portion  224  is formed between the protruding portions  221  and  223 . The protruding portion  222  is provided around the center of the arc-shaped recessed portion  224 , and protrudes from the upper surface edge of the second drive gear  220 . In the initial state, the protruding portion  221  is engaged by the recessed portion  206 a. The second drive gear  220  may be rotated by a predetermined angle to realize the poles P 1 , P 5 ( 8 ), P 8 , and P 9  raising operations  131 .  
         [0130]     The third drive gear  230  includes an upper drive gear  235 , a lower drive gear  236 , and a helical torsion spring  237  that is provided between the upper and lower drive gears  235  and  236 . Normally, the upper drive gear  235  and the lower drive gear  236  are rotated integrally. The upper drive gear  235  includes a gear portion  235   a  across the entire periphery of the upper drive gear  235 . The lower drive gear  236  includes a gear portion  231  that extends across approximately a 270-degree angle, and first and second protruding portions  232  and  233  protruding in an outer radial direction. The first and second protruding portions  232  and  233  are slightly set apart from each other. The first protruding portion  232  is arranged to correspond to the depth of the recessed portion  202 , and the second protruding portion  233  is arranged to correspond to the depth of the arc-shaped recessed portion  203  (i.e, the first protruding portion  232  protrudes higher than the second protruding portion  233 ). In the initial state, the second protruding portion  233  is engaged with the arc-shaped recessed portion  203 , and the partial gear portion  231  is not engaged with the gear portion  201 . The third drive gear  230  may be rotated by a predetermined angle to realize the pole P 5 ( 8 ), P 8 , and P 4 ( 8 ) moving operations  133 . The helical torsion spring  237  is twisted at the last stage of the operation to generate a force for urging the poles P 5 ( 8 ), P 8 , and P 4 ( 8 ) to their corresponding stoppers.  
         [0131]     In the following, rotation transmitting operations for transmitting a rotational motion from the individual mode switching gear  200  to the first, second, and third drive gears  210 ,  220 , and  230  are described.  
         [0132]     When the individual operations motor  60  is driven to rotate in a clockwise direction, the rotation is transmitted via the worm gear mechanism  61 , and the individual mode switching gear  200  is rotated in a clockwise direction by approximately 30 degrees. When the individual operations motor  60  is rotated in the reverse direction, namely, in a counter-clockwise direction, the individual mode switching gear  200  is rotated in a counter-clockwise direction by approximately 360 degrees.  
         [0133]     When the individual mode switching gear  200  is rotated from the initial state in a clockwise direction by a predetermined angle, the protruding portion  212  is pushed, the gear portion  205  engages the partial gear portion  211  (see  FIG. 25A ), and the first drive gear  210  is rotated in a counter-clockwise direction (see  FIG. 25B ) to reach the position as is indicated in  FIG. 25C . It is noted that during this operation, the second and third drive gears  220  and  230  are maintained at standstill states. When the individual mode switching gear  200  is rotated in a direction for returning to the initial state from the rotated state, the first drive gear  210  is rotated in a clockwise direction to be set back to the initial state.  
         [0134]     Also, when the individual mode switching gear  200  is rotated from the initial state in a counter-clockwise direction by a predetermined angle, the protruding portion  221  is pushed by the edge of the recessed portion  206   a,  and the second drive gear  220  is rotated in a clockwise direction by a predetermined angle (see  FIG. 26A ). When the second drive gear  220  is rotated and the protruding portion  221  passes the recessed portion  206   a,  the recessed portion  224  faces the cam portion  206 , and the second drive gear  220  is maintained at this position thereinafter. In this state, the protruding portion  222  is positioned at the upper surface side of the cam portion  206 .  
         [0135]     When the individual mode switching gear  200  is rotated further in a counter-clockwise direction, the edge of the arc-shaped recessed portion  203  pushes the second protruding portion  233  to induce an initial rotation of the third drive gear  230  (see  FIG. 26B ). Then, as is shown in  FIG. 26C , the gear portion  201   a  and the gear portion  231  are engaged with each other, and the third drive gear  230  is rotated in a clockwise direction. When the third drive gear  230  is rotated by approximately 270 degrees, the first protruding portion  232  enters the recessed portion  202  (see  FIG. 27A ), the protruding portion  207  pushes the first protruding portion  232  (see  FIG. 27B ), and the rotation of the third drive gear  230  is transmitted with a strong force to reach a final position as is shown in  FIG. 27C . In this state, the first protruding portion  232  is positioned past the recessed portion  202  and the second protruding portion  233  is inserted into the arc-shaped recessed portion  203 . It is noted that during this operation, the first drive gear  210  is maintained at a standstill state.  
         [0136]     When the individual mode switching gear  200  is rotated in a direction for returning to the initial state from the rotated state, first, the third drive gear  230  is rotated in a counter-clockwise direction to be set back to the initial state. Then, the pin portion  206   c  pushes the protruding portion  222 , and the second drive gear  220  is rotated in a counter-clockwise direction to return to the initial state.  
         [0137]     9. [Individual Operations] 
         [0138]     In the following, the operations  121 ,  131 , and  133  are described in detail.  
         [0139]     [Poles P 4 ( 4 ) and P 5 ( 4 ) Moving Operations  122 ] (see  FIGS. 28 and 29 )  
         [0140]      FIG. 28  shows the initial state of a pole moving mechanism for moving the poles P 4 ( 4 ) and P 5 ( 4 ).  FIG. 29  shows the state of the pole moving mechanism after the poles P 4 ( 4 ) and P 5 ( 4 ) are moved. When the first drive gear  210  is rotated in a counter-clockwise direction by the individual mode switching gear  200 , a slide lever  250  is slid in the Y 2  direction, and a slide lever  252  is slid in the X 2  direction via a rotation lever  251 . In response to the sliding motion of the slide lever  252 , first, a rotating lever  253  is rotated in a clockwise direction around a stationary axis  254 , and a rotating lever  256  is rotated in a counter-clockwise direction around a stationary axle  257  via a link  255 . The rotational force of the rotating lever  256  is transmitted to the pole P( 4 ) via a link  258 , and the pole P 4 ( 4 ) moves in the Y 1  direction along the guide rail portion  147  until reaching the position of the stopper  151  as is shown in  FIG. 29 . Second, in response to the sliding motion of the slide lever  252 , a rotating lever  260  is rotated in a clockwise direction around a stationary axle  261 , and this rotation is transmitted to the pole P 5 ( 4 ) via a link  262 . In turn, the pole P 5 ( 4 ) moves in the Y 1  direction until reaching the position of the stopper  154  as is shown in  FIG. 29 .  
         [0141]     When the first drive gear  210  is rotated in a clockwise direction from the rotated state, the pole moving mechanism for the poles P 4 ( 4 ) and P 5 ( 4 ) is set back to the initial state as is shown in  FIG. 28  from the state shown in  FIG. 29 .  
         [0142]     [Poles P 1 , P 5 ( 8 ), P 8 , and P 9  Raising Operations] (see FIGS.  30  though  33 )  
         [0143]      FIG. 30  shows the initial state of a pole raising/lowering mechanism for the poles P 1 , P 5 ( 8 ), P 8 , and P 9 .  FIG. 31  shows the state of the pole raising/lowering mechanism after the poles P 1 , P 5 ( 8 ), P 8 , and P 9  are raised.  
         [0144]     When the second drive gear  220  is rotated in a clockwise direction by the individual mode switching gear  200 , a slide lever  300  is slid in the Y 1  direction, and a slide lever  302  is slid in the Xl direction via a rotating lever  301 . The slide lever  300  includes a cam trench  304 , and the slide lever  302  includes racks  305  and  306 .  
         [0145]     It is noted that a see-saw type pole raising/lowering mechanism  270  is provided for the pole P 1 , a spiral cam type pole raising/lowering mechanism  280  is provided for the poles P 5 ( 8 ) and P 8 , and a spiral cam type pole raising/lowering mechanism  290  is provided for the pole P 9 .  
         [0146]     The pole raising/lowering mechanism  270  includes a lever  271  having a center axle  272  that is supported by a bracket  275  to oscillate back and forth. A pin  273  at the Y 1  side end of the lever  271  is engaged with the cam trench  304  of the slide lever  300 , and a forked portion at the Y 2  side end of the lever  271  is connected to the sleeve  182 .  
         [0147]     When the slide lever  300  is slid in the Y 1  direction, the lever  271  is rotated by the cam trench  304  in a direction that causes the forked portion  274  to be raised, and the sleeve  182  is moved in the Z 1  direction along the stationary post  186  so that the pole P 1  is raised (see  FIG. 31 ).  
         [0148]     The pole raising/lowering mechanism  280  includes a spiral cam member  281  and a raising/lowering member  285  (see  FIG. 32 ). The spiral cam member  281  has a spiral cam trench  282  formed around its cylindrical portion, and a gear  283  provided at its bottom portion. The spiral cam member  281  is engaged and supported by a stationary post that is fixed to the chassis base. The gear  283  is engaged with the rack  305  of the slide lever  203 . The raising/lowering member  285  includes a cylindrical portion  286  that is engaged with the spiral cam member  281 , a cam follower  287  that is engaged with the spiral cam trench  282 , and a U-shaped trench portion  288  that is engaged by and fit to a stationary post  307  that is fixed to the chassis base. A stage  289  (see  FIG. 31 ) is fixed to the upper surface of the raising/lowering member  285 , and the poles P 5 ( 8 ) and P 8  are supported by the stage  289 .  
         [0149]     As is shown in  FIG. 31 , when the slide lever  302  is slid in the X 1  direction, the spiral cam member  281  is rotated in a clockwise direction by the rack  305 , the cam follower  287  is guided by the spiral cam trench  282 , the raising/lowering member  285  is moved in the Z 1  direction, and the poles P 5 ( 8 ) and P 8  are raised along with the stage  289 . It is noted that the poles P 5 ( 8 ) and P 8  may be raised by moving one end of links  340  and  342  shown in  FIG. 34 .  
         [0150]     The pole raising/lowering mechanism  290  has a same structure as that of the pole raising/lowering mechanism  280 . As is shown in  FIG. 33 , the pole raising/lowering mechanism  290  includes a spiral cam member  291  and a raising/lowering member  295 . The spiral cam member  291  is engaged and supported by a stationary post that is fixed to the chassis base, and includes a gear  293  that is engaged with the rack  306 . The raising/lowering member  295  includes a cylindrical portion  296  that is engaged with the spiral cam member  291 , a cam follower  297  that is engaged with the spiral cam trench  292 , and a U-shaped trench portion  298  that is engaged by and fit to a stationary post  308  that is fixed to the chassis base. A stage  299  (see  FIG. 31 ) is fixed to the upper surface of the raising/lowering member  295 , and the stage  299  supports the arms  183  and  184  (see  FIG. 21 ).  
         [0151]     As is shown in  FIG. 31 , when the slide lever  302  is slid in the X 1  direction, the spiral cam member  291  is rotated in a counter-clockwise direction by the rack  306 , the cam follower  297  is guided by the spiral cam trench  292 , the raising/lowering member  295  and the stage  299  are moved in the Z 1  direction, the arms  183  and  184  are raised by the stage  299 , the sleeve  185  is slid in the Z 1  direction along the stationary post  187 , and the pole P 9  is raised along with the arms  183  and  184 .  
         [0152]     When the second drive gear  220  is rotated in a counter-clockwise direction from the rotated state, the pole raising/lowering mechanism is set back to the initial state as is shown in  FIG. 30  from the state shown in  FIG. 31 .  
         [0153]     [Poles P 5 ( 8 ), P 8 , and P 4 ( 8 ) Moving Operations  133 ] (see  FIGS. 34 and 35 )  
         [0154]      FIG. 34  shows the initial state of a pole moving mechanism for the poles P 5 ( 8 ), P 8 , and P 4 ( 8 ).  FIG. 35  shows the state of the pole moving mechanism after the poles P 5 ( 8 ), P 8 , and P 4 ( 8 ) are moved.  
         [0155]     The pole moving mechanism of  FIGS. 34 and 35  includes a ring structure  310 . The ring structure  310  is supported by the chassis base at its inner circumferential area, and is arranged to surround the rotating drum unit  31 . The ring structure  310  includes a first ring member  311  and a second ring member  312  that face each other and are attached together by arc-shaped holes and pins. The first and second ring members  311  and  312  are arranged to be able to rotate relative to each other over a predetermined angle range, and are pulled in one direction by a tension spring  313  to form an integral structure. It is noted that a gear portion  314  is formed at the first ring member  311  across a predetermined angle range, and the gear portion  235   a  of the third drive gear  230  and the gear portion  314  of the ring structure  310  are arranged to be engaged with one another.  
         [0156]     As is shown in the drawings, a fan-shaped gear  320  that includes a gear portion  321  and is supported by a stationary post  322  extending from the chassis base is positioned at the X 2  side of the ring structure  310 . A protruding portion  325  is provided at an edge of the gear portion  321 .  
         [0157]     Also, a slide board  330  that is arranged to slide in the Y 1  direction is engaged with the fan-shaped gear  320 . The slide board  330  includes an elongated hole  331  into which the tip of a pin  324  of an arm portion  323  of the fan-shaped gear  320  is inserted to realize the engagement between the slide board  330  and the fan-shaped gear  320 .  
         [0158]     The pole P 5 ( 8 ) is connected to the first ring member  311  via the link  340 . The pole P 8  is connected to the second ring member  312  via the link  342 . A rotating arm  343  is supported by a stationary post extending from the chassis base, and the pole P 4 ( 8 ) is connected to the tip of the rotating arm  343  via a link  345 . A pin  346  is provided at a middle section of the rotating arm  343 , and the pin  346  is engaged with a U-shaped cut portion  332  of the slide board  330 .  
         [0159]     When the third drive gear  230  is rotated in a clockwise direction by the individual mode switching gear  200 , the ring structure  310  is rotated in a counter-clockwise direction owing to the engagement between the gear portion  235   a  and the gear portion  314  so that the poles P 5 ( 8 ) and P 8  start moving. At a point where the poles P 5 ( 8 ) and P 8  are still being moved, the protruding portion  325  is pushed by a protruding portion of the ring structure  310  to induce the initial rotation of the fan-shaped gear  320  in a clockwise direction. Then, the gear portion  314  engages the gear portion  321 , the fan-shaped gear  320  is rotated in a clockwise direction, the slide board  330  is slid in the Y 1  direction, the rotating arm  343  is rotated in a counter-clockwise direction, the link  345  is pushed, and the pole P 4 ( 8 ) starts moving.  
         [0160]     As is shown in  FIG. 35 , the poles P 5 ( 8 ), P 8 , and P 4 ( 8 ) move until reaching the stoppers  152 ,  153 , and  151 , respectively. At this point, the first ring member  311  may not rotate any further in a counter-clockwise direction, and since the gear portion  235   a  and the gear portion  314  engage with one another, the upper drive gear  235  of the third drive gear  230  may not rotate any further. The rotation of the individual mode switching gear  200  continues for some time, and in turn, only the lower drive gear  236  of the third drive gear  230  rotates in a clockwise direction while twisting the helical torsion spring  237 . When the rotation of the individual mode switching gear  200  is stopped, the spring force of the helical torsion spring  237  is transmitted via the upper drive gear  235  to the ring structure  310  and the fan-shaped gear  320 . In turn, the ring structure  310  is urged toward a counter-clockwise direction, and the pole P 5 ( 8 ) is pushed to the stopper  152  by this force. Also, the fan-shaped gear  320  is urged toward a clockwise direction, and the pole P 4 ( 8 ) is pushed to the stopper  151  by this force. The pole P 8  is urged to the stopper  153  by the spring force of the tension spring  313  of the ring structure  310 .  
         [0161]     When the third drive gear  230  is rotated in a counter-clockwise direction from the rotated position, the pole moving mechanism in the state shown in  FIG. 35  is set back to the initial state shown in  FIG. 34 .  
         [0162]     Also, it is noted that in the illustrated embodiment, the common mode is independently determined by the common mode switching gear  171 , and the individual mode is independently determined by the individual mode switching gear  200 . Therefore, the order of performing common mode operations and individual mode operations may be easily changed with software, for example.  
         [0163]     Further, it is noted that the present invention is not limited to the specific embodiments described above, and variations and modifications may be made without departing from the scope of the present invention. For example, the present invention may be applied to a recording/reproducing device using a magnetic tape other than a streamer device.  
         [0164]     The present application is based on and claims the benefit of the earlier filing date of Japanese Patent Application No. 2004-288244 filed on Sep. 30, 2004, the entire contents of which are hereby incorporated by reference.