Abstract:
A medium transfer mechanism of a recording medium storage apparatus is provided, which is capable of reducing a load on a motor or a gear, when a recording medium is transferred. In order to store a recording medium T in libraries L 1  and L 2 , the medium transfer mechanism of a recording medium storage apparatus includes a driving side engaging element which is moved by a motor. A follower side engaging element engages with the driving side engaging element. A predetermined gap is between the driving side engaging element and the follower side engaging element. A biasing device biases the follower side engaging element for engaging with the driving side engaging element.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a recording medium storage apparatus and particularly relates to a recording medium transfer mechanism of the recording medium storage apparatus in order to transfer the recording medium to be stored in a library. 
     2. Background Art 
     In a storage apparatus for storing a recording medium such as magnetic tapes, sometimes it is necessary to transfer recording media for loading or unloading by use of a motor. FIG. 8 is a schematic representation showing a conventional medium transfer mechanism V, in which the reference letter T denotes a magnetic tape, L 1  and L 2  denote libraries, numeral  30  denotes a medium supporting device, and  31  denotes a motor. Here, two libraries L 1  and L 2  are arranged inserting the medium transfer mechanism V between two libraries. 
     The medium transfer mechanism V shown in FIG. 8 comprises a swivel gear  32  fixed under the medium supporting device  30 , such that the medium supporting device  30  can rotate by means of a driving gear  33  attached to the motor  31 . On the upper surface of the medium supporting device  30 , a hand mechanism  34  for loading and unloading magnetic tapes to the libraries L 1  and L 2  is provided to be capable of performing reciprocating motion in the longitudinal direction of the medium supporting device  30 . Owing to those components, when the medium supporting device  30  rotates, a magnetic tape supported by the hand mechanism  34  turns (swivel). In addition, an engagement of the medium supporting device  30  with the stopper portion  35  locates the rotating direction for loading and unloading to the libraries L 1  and L 2 . 
     However, since the conventional medium transfer mechanism V comprises a swivel gear  32  fixed under the medium supporting device  30 , a large stress to the driving gear  33  and the motor  31  results due to the impact force at the time of engagement of the medium supporting device  30  with the stopper portion  35 . Thus, a problem arises in that the driving gear  33  and the motor  31  are likely to suffer damage due to the repeatedly applied stress. 
     SUMMARY OF THE INVENTION 
     It is therefore an objective of the present invention to provide a medium transfer mechanism of a medium storage apparatus, which is capable of reducing the load applied to the motor or the gear and ensuring the stable motion for a long period of time. 
     According to the first aspect, a medium transfer mechanism of a recording medium storage apparatus, in which the medium supporting device supporting the recording medium is transferred for storing the recording medium in a library and the medium supporting device is positioned by abutting with a stopper; comprises: a driving side engaging element which is moved by a motor; a follower side engaging element which is engaged with the driving side engaging element having a predetermined gap between said driving side engaging element; and a biasing device for biasing said follower side engaging element for engaging with said driving side engaging element. 
     According to the second aspect, in a medium transfer mechanism of a recording medium storage apparatus according to the first aspect, the medium transfer mechanism further comprises a control device for controlling said motor so as to stop said driving side engaging element at a predetermined location. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are diagrams showing schematic structures of the embodiment of the present invention. 
     FIG. 2 is an operational diagram showing the operation of the embodiment of the present invention. 
     FIG. 3 is an operational diagram showing the operation of the embodiment of the present invention. 
     FIG. 4 is an operational diagram showing the operation of the embodiment of the present invention. 
     FIG. 5 is an operational diagram showing the operation of the embodiment of the present invention. 
     FIG. 6 is an operational diagram showing the operation of the embodiment of the present invention. 
     FIG. 7 is an operational diagram showing the operation of the embodiment of the present invention. 
     FIG. 8 is a schematic diagram showing a conventional medium transfer mechanism. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to  7 . FIGS. 1A and 1B are diagrams showing schematic structures of a medium transfer mechanism S in a magnetic tape storage apparatus, wherein FIG. 1A is a side view and FIG. 1B is a plan view showing the structure of its main portion. In addition, the numeral  1  denotes a medium supporting device,  2  denotes a driving device,  3  a biasing device, and  4  a support device. 
     The medium supporting device  1  mainly comprises a swivel base which is fixed by fittingly inserting a swivel shaft and a hand mechanism  12  mounted on the upper surface of the swivel base  11 . The swivel shaft  10  is rotatably supported by the support device  4 ; thereby the medium supporting device  1  as a whole is rotatable about the rotation axis p of the swivel shaft  10 . 
     At the lower surface of the swivel base  11 , the cam follower  13  fit at an eccentric position from the rotation axis p and a swivel stud  14 , which is a follower side element of the engaging portion, are installed protruding downward. Furthermore, the hand mechanism  12  possesses an arm  15  capable of supporting a magnetic tape, and the arm  15  is constructed so as to carry out the reciprocation motion. 
     The driving device  2  comprises a driving motor  16  and an encoder  17  for detecting the rotating position of the motor  16 . A driving gear  18  is installed at the output axis of the motor  16 , and the driving gear  18  is formed so as to be engaged with an swivel gear  19 , rotatably supported by the swivel shaft  10  at the lower side of the swivel base  11 . An engaging hole  19   a  is formed in the swivel gear  19  constituting a driving side engaging portion, and the engaging hole  19   a  is formed so as to engage with the swivel stud  14  of the swivel base  11 . The encoder  17  is connected with a control device  20  for controlling the motor  16  through the encoder  17 . 
     The inner diameter of the engaging hole  19 A is formed larger than that of the swivel stud  14  of the swivel base  11  so as to define a gap between the stud and the hole when engaged. In the present embodiment, the inner diameter of the engaging hole  19   a  is formed larger than that of the swivel stud  14  so as to allow the swivel stud  14  rotating 10 degrees about the rotation axis p in the engaging hole  19   a.    
     The biasing device  3  comprises a detente plate  21  disposed between the swivel base  11  and the swivel gear  19 , springs  22  disposed so as to pull the detente plate  21  by the spring force (biasing force) in the direction of W shown by an arrow in FIG. 1B, and a bearing  23  for guiding the movement of the detente plate  21  while inserted in a U-shaped groove  21   a  formed in the detente plate  21 . A guide groove  21   b  is formed in a detente plate  21  for guiding a cam follower  13  of the swivel base  11 , and the medium supporting device  1  is pulled either one of directions R or L shown by arrows in FIG. 1B, by the cam follower  13  moving along the guide groove  21   b.    
     The support device  4  is used for positioning the medium supporting device  1  in the rotation direction to the library L 1  or L 2  by abutting a side surface of the hand mechanism  12  of the medium supporting device  1  to one of two stoppers  24  disposed at the respective side surfaces of the library L 1  and the library L 2 . 
     Next, an operation of the medium transfer mechanism will be described with reference to FIGS. 1 to  7 . Hereinafter, a case of rotating the hand mechanism  12  from the library L 1  to the library L 2  will be described. 
     Once the power supply is activated, the control device drives the motor  16  for setting a home position for detecting the position of the hand mechanism  12 . As shown in FIG. 2, the swivel gear is rotated at a low speed in the direction shown by an arrow R in the figure until the side surface of the hand mechanism  12  abuts to the stopper  24  and the engaging hole  19   a  of the swivel gear  19  abuts to the L side surface of the swivel stud  14 . Here, the hand mechanism  12  moves together with the swivel stud  14 . 
     Next, the swivel gear is rotated 5 degrees from the home point toward the L side shown by the arrow. That is, as shown in FIG. 3, the side surface of the hand mechanism  12  abuts to the stopper  24  by the biasing force of the spring  22 , and the engaging hole  19   a  and the swivel stud  14  are separated from each other. As described earlier, since the diameter of the engaging hole  19   a  is formed such that the swivel stud  14  can be displaced in the hole by 10 degrees, the above 5 degree rotation provides gaps corresponding to 5 degrees on both sides of the moving direction of the stud  14 . This is a standby position for the hand mechanism  12  on the side of the library L 1 . The biasing force  22  is conducted to the swivel base  11 , on which the hand mechanism  12  is loaded. 
     When an instruction is given to move toward the library L 2 , the control device  20  makes the swivel gear  19  rotate toward the arrow L. When the swivel gear  19  rotates from the ready position by 5 degrees toward the arrow L, the R side surface of the stud  14  abuts to the engaging hole  19   a . Further rotating movement of the swivel gear  19  makes the detente plate slide by being pushed by the cam follower  13  opposing against the biasing force of the spring  22  (FIG.  5 ). The hand mechanism  12  is biased by a spring  22  in the direction toward R when located at the R side from the position shown in FIG. 5, or toward the L when located at the L side from the position of FIG.  5 . 
     When the swivel gear  19  is rotated by 180 degrees from the home position, the hand mechanism  12  abuts to the stopper  24 . At this time, since the hand mechanism  12  is biased toward the L position, the swivel stud  14  abuts to the arrow R side of the engaging hole  19   a , that is, the side of the engaging hole opposite to the stopper, so that the space is generated at the arrow R side of the engaging hole. Therefore, the swivel gear  19  is further rotatable toward the L side. 
     The swivel gear  19  is further rotated by 5 degrees and is stopped at the position apart by 185 degrees from the home position. At this time, the same gaps corresponding to 5 degrees are formed on both side of moving directions of the swivel stud  14 , and this is the standby position on the side of the library L 2 . 
     By a series of operations, the magnetic tapes T can be transferred by rotation of the hand mechanism from the library L 1  to the library L 2 . Subsequently, a loading operation of a magnetic tape T is executed by the hand mechanism  12 . The rotating operation from the library L 2  to the library L 1  is executed in the opposite direction from a series of the above described operations. 
     In the present embodiment, the swivel stud, which is the follower side element, engages with the engaging hole, which is the driving side element, while the swivel stud is pulled by the biasing force of the spring  22 . Thus, the shock at the time when the hand mechanism  12  abuts to the stopper  24  acts in the direction to separate the swivel stud  14  from the engaging hole  19   a . Since the size of the engaging hole is formed such that the swivel stud  14  is movable by 10 degrees, the shock at the time of abutment does not act or is not transmitted to the swivel stud  14 . Thus, it is possible to reduce the load on the motor  16  and the driving gear  18 . 
     Furthermore, in the present embodiment, since the control device  20  controls the rotation of the motor  116 , it is also possible to stop in a reliable manner the hand mechanism  12  at the position where the swivel stud  14  is separated from the engaging hole  19   a , after the hand mechanism  12  abuts to the stopper  24 . Thereby, the load on the engaging hole  19   a  can be always reduced other than at the time of abutting to the stopper  24 . 
     In the present embodiment, it is defined that the engaging hole  19   a  is the driving side element, and the swivel stud is the follower side element. However, the invention is not limited to the above combination, and it is possible to use other combinations if the combined elements engaging each other have a gap therebetween. For example, it is possible to adapt a rod element as a driving side element, and a hole formed in said rod element as the follower side element. In addition, the size of the gap or the clearance is not limited to the size corresponding to 10 degrees as described in the above description. 
     As described above, the following effects are obtained by the present invention. 
     Since the medium transfer mechanism of the present invention comprises a biasing device for biasing the follower side engaging element for engaging with the driving side engaging element which is moved by the motor, the shock when the medium supporting device abuts to the stopper acts to separate the driving side engaging element from the follower side engaging element. Since the driving side engaging element and the follower side engaging element engage each other with a gap therebetween, the shock at the time of abutment does not act on the driving side engaging element. Therefore, the load on the driving side motors and gears can be reduced. As a result, it is possible to enhance the durability of the motor or gears, ensuring the stable operation for a long time, and miniaturization of this mechanism is facilitated at reduced cost. 
     According to the second aspect, since the medium transfer mechanism further comprises a control device for controlling said motor so as to stop said driving side engaging element at a predetermined location, it is possible to further reduce the load on the motor or the gear.