Abstract:
A medical device supporting apparatus for supporting a medical device in a three-dimensional space, in which a holding device for holding the medical device is supported by a supporting mechanism three-dimensionally, and the state of the supporting unit is switched between the movable state and the locked state by operating a plurality of final control elements. Operation is stabilized by differentiating the amount of operating force of the plurality of final control elements.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is based upon and claims the benefit of priority from prior Japanese Patent Application Nos. 2003-345995, filed on Oct. 3, 2003 and 2004-036663, filed on Feb. 13, 2004, the entire contents of each of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a medical device supporting apparatus used for positioning a medical device at an operative portion. For example, a medical device supporting apparatus of the invention is used for positioning an endoscope with respect to the operative portion in a surgical operation during a cranial nerve surgery.  
         [0004]     2. Description of the Related Art  
         [0005]     Generally, there is a medical device supporting apparatus for supporting a medical device disclosed in JP-A-2002-345831. The medical device supporting apparatus includes a plurality of arms connected via joints provided with brakes for locking and unlocking rotation thereof. The medical device supporting apparatus holds an endoscope by a holding device and locks the joints in a state of being faced toward the operative portion to be observed. Accordingly, since the visual field can be fixed without displacement, the operator can concentrate on the operation, thereby enabling an efficient operation.  
         [0006]     As shown in  FIG. 13 , such a medical device supporting apparatus includes a grip member  2  extending substantially orthogonal to an insertion axis of an endoscope  1  for locking and unlocking the joint brakes as a grip member to be provided in the vicinity of the holding device, to which the endoscope is attached, for moving the apparatus. Two operating switches  3   a ,  3   b  are provided substantially symmetrically with respect to the grip member  2 . These two operation switches  3   a ,  3   b  are used in such a manner that the operator grips the grip member  2  as shown in  FIG. 14 , keeps pressing them simultaneously with his/her thumb and first finger to release the brakes, and unlocks the respective joints. Also, as shown in  FIG. 15 , the respective joints are locked in a state other than the state in which these two operating switches  3   a ,  3   b  are pressed simultaneously. Accordingly, the operator can concentrate on the operation without being absorbed in anxiety for erroneous unlocking of the brakes during surgical operation.  
         [0007]     Also, the medical device supporting apparatus is required to have a substantial locking force in a state in which the brakes for the joints are locked so as not to be moved inadvertently in case where the operator happens to touch the arms, and simultaneously, to have a locking ability so that the operator can move the medical device in his/her hand lightly when they are unlocked and brought into a free state. In addition, it is also designed so that the brakes are maintained in a locked state in case of failure.  
         [0008]     In the medical device supporting apparatus, in order to turn the operation switches  3   a ,  3   b  OFF to lock the respective joints after having moved the medical device, both of the two operation switches  3   a ,  3   b  are turned OFF. In this case, when the operator releases a force of his/her thumb and first finger which press the two operation switches  3   a ,  3   b , which finger comes off the switch first is unknown. In addition, according to the medical device supporting apparatus described above, when it is applied in the field of a cranial nerve surgery for example, it is often moved in accordance with the progression of the surgical operation in an operating room in which various types of equipment are arranged. Therefore, there is a risk that somebody steps on the power cable when moving the apparatus including such equipment, which may result in disconnection of the power cable or failure of the brake control system. When disconnection of the power cable or failure of the brake system happens as described above, there arises a necessity to move the arm, which holds the medical device such as an endoscope, in a state in which the endoscope is inserted into the body cavity, and then pulled out from the body cavity. In this case, since the respective joints are in the locked state, it is necessary to move the arm against a locking force of the brake for the joint.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     A medical device supporting apparatus according to the invention includes a supporting mechanism which can move three-dimensionally and lock a holding device for holding the medical device for observing or giving medical treatment to the operative portion, a control unit for controlling movement or locking of the holding device, and at least two final control elements for giving instructions for the operation to the control unit, and is characterized in that the amount of operating force of the respective final control element are differentiated.  
         [0010]     In this arrangement, at least two final control elements being different in the amount of operating force, is turned OFF sequentially from the one having a larger operating force when the amount of operating force is reduced for releasing the operation. Therefore, the user (the operator) can recognize completion of operation of two final control elements reliably. Therefore, locking and unlocking operation of the medial treatment device with high degree of reliability and accuracy can be realized simply and easily.  
         [0011]     Preferably, the holding member is restored from the moving state to the locked state by the control unit in a state in which one of the aforementioned two operating members is released.  
         [0012]     When controlling the state of the holding members as described above, the operation of the operating member having the largest operating force is released first when the user weakens the force for releasing the operation of the operating member. In other words, the operating member which is released first is fixed, and hence when the operation of this specific operating member is released, the holding device is restored to the locked state. Therefore, the restoring operation from the moving state to the locked state is stabilized and is performed quickly.  
         [0013]     A medical device supporting apparatus of the invention includes a supporting mechanism for supporting the holding device for holding the medical device for observing and giving medical treatment to the operative portion three-dimensionally so as to be movable and lockable, the supporting mechanism having a plurality of arms rotatably connected via joints which can be locked and unlocked of rotation, a control unit for controlling movement and locking of the holding device by locking and unlocking the rotation of the joints of the supporting mechanism, an input mechanism for giving instructions for the operation of the control unit, and a locking force adjusting mechanism for adjusting a locking force for locking the rotation of the joints.  
         [0014]     In this arrangement, the medical device locked in position and supported by the supporting mechanism can adjust the movement of the joints by adjusting the force for locking the joints without performing the locking and unlocking operation of the joints of the supporting mechanism. Therefore, even in the case in which the locking state of the joints can hardly be released by the control unit, the supporting mechanism can be moved by weakening the locking force, so that the movement of the medical device including retraction is enabled. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWINGS  
       [0015]     These and other features, aspects, and advantages of the apparatus and methods of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:  
         [0016]      FIG. 1  is a perspective view showing a structure of a medical device supporting apparatus according to a first embodiment of the present invention;  
         [0017]      FIG. 2  is a partial cross-sectional view illustrating layout of first and second switch levers with respect to a holding device shown in  FIG. 1 ;  
         [0018]      FIGS. 3A, 3B  are explanatory drawings illustrating a structure of joints in  FIG. 1 ;  
         [0019]      FIG. 4  is a cross-sectional view of a portion of the medical device supporting apparatus according to a second embodiment of the present invention;  
         [0020]      FIG. 5  is a cross-sectional view illustrating a locking force adjusting mechanism disposed at the joints of the medical device supporting apparatus according to the second embodiment shown in  FIG. 4 ;  
         [0021]      FIG. 6  is a circuit diagram of a motor control system in  FIG. 5 ;  
         [0022]      FIG. 7  is a perspective view showing a structure of the medical device supporting apparatus according to a third embodiment of the invention;  
         [0023]      FIG. 8  is a block diagram showing an air pressure control unit in  FIG. 7 ;  
         [0024]      FIG. 9  is a detailed drawing showing a stopper in  FIG. 7 ;  
         [0025]      FIG. 10  is a partial cross-sectional view showing a holding device in which an input portion in  FIG. 7  is disposed;  
         [0026]      FIG. 11  is a perspective view showing the structure of the medical device supporting apparatus according to a fourth embodiment of the invention;  
         [0027]      FIG. 12  is a partial cross-sectional view of a portion in  FIG. 11 ;  
         [0028]      FIG. 13  is a drawing illustrating problems in the related art;  
         [0029]      FIG. 14  is a drawing showing a positional relationship with respect to a switch in a holding state in  FIG. 13 ; and  
         [0030]      FIG. 15  is a drawing showing change-over operation of the switch in  FIG. 13 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]     Preferred embodiments of the invention will be described below with reference to the accompanying drawings.  
         [0032]      FIG. 1  shows a medical device supporting apparatus according to a first embodiment of the present invention. A supporting base  10  is detachably attached to a mounting body  11  such as a floor or a bed. Arms  12   a ,  12   b ,  12   c  are joined to the supporting base  10  via joints  13   a ,  13   b ,  13   c  in sequence. A holding device  15  for mounting a medical device is attached to the distal arm  12   a  via a ball joint  14 . The ball joint  14  can include an electromagnet (not shown), which has an electromagnetic brake built therein. The electromagnet (not shown) is electrically connected to a control box  16  which constitutes a control unit, and is driven under the control of the control box  16 . In other words, the electromagnet (not shown) performs locking and unlocking of the position of the ball joint  14  according to presence or absence of electric distribution.  
         [0033]     As a medical device for giving treatment or observing a patient, for example, an endoscope  17  is inserted into and supported by the holding device  15 . The holding device  15  is provided with first and second switch levers  18 ,  19 , which correspond to the final control elements, on both sides of the endoscope  17  so as to be operated in opposite directions. The first and second switch levers  18 ,  19  are rotatably supported via hinges  181 ,  191  at one end of each as shown in  FIG. 2 , and the proximal ends thereof are opposed to first and second micro switches  20 ,  21  disposed on the holding device  15 . The first and second micro switches  20 ,  21  are electrically connected to the electromagnet (not shown) on the ball joint  14  and to electromagnets disposed on the joints  13   a - 13   c , respectively (as discussed below).  
         [0034]     The first and second switch levers  18 ,  19  are attached to the holding device  15  at midsections thereof via a first and second spring members  182 ,  192 , and are restored to the initial positions (OFF positions of first and second micro switches  20 ,  21 ) by biasing forces of the first and second spring members  182 ,  192 . The first and second spring members  182 ,  192  are set to different spring constants Ka, Kb, respectively, having a relation of Ka&lt;Kb for example, and the amount of the operating force of the first and second switch levers  18 ,  19  are set based on the spring constants.  
         [0035]     Referring now to  FIGS. 3A and 3B , the joints  13   a ,  13   b ,  13   c  will be described. However, since the joints are configured substantially in the same manner, the joint  13   a  will be described as a representative for convenience of explanation.  
         [0036]     A joint member  31  is rotatably attached to a housing  30  about an axis  02  via a joint shaft  32 . The distal end of the arm  12   a  is attached to the housing  30 , and the distal end of the arm  12   b  is attached to the other joint member  31 .  
         [0037]     The joint member  31  is provided with a brake disk  33 , and for example, an iron-made brake shoe  34  provided on the joint shaft  32  is opposed to the brake disk  33  so as to be capable of coming into and out of contact thereto. The brake shoe  34  is fitted into a key groove  321  provided on the joint shaft  32  so as to be capable of moving and is rotated about the axis  02  integrally with the joint shaft  32 .  
         [0038]     The housing  30  is provided with a cam  301 , such as a slot, and a pin  35  which constitutes a rotational force adjusting mechanism is operably inserted into the cam  301 . The operating tab  35  is rotatably supported at the distal end thereof about the joint shaft  32  and the rotary axis  02 , and when it is urged to rotate about the rotary axis  02 , it is moved along the cam  301  to the position indicated by broken lines in  FIGS. 3A and 3B .  
         [0039]     A spring member  36  is engaged between the operating tab  35  and the brake shoe  34 . The spring member  36  presses the brake shoe  34  against the brake disk  33  by its biasing force, and restricts the rotation of the joint member  31  by a frictional force generated at that time. Accordingly, when the operating tab  35  is moved along the cam  301 , it varies the biasing force of the spring member  36  and varies a frictional force between the brake disk  33  and the brake shoe  34 , so that the fixing force against the rotation of the joint member  31  is variably adjusted.  
         [0040]     The housing  30  is provided with an electromagnet  37  so as to oppose the brake shoe  34 . The electromagnet  37  pulls the brake shoe  34  by an electromagnetic force against the biasing force of the spring member  36 . In other words, the electromagnet  37  is electrically connected to the control box  16 , and turns the second micro switch  210 N in conjunction with the operation of the second switch lever  19 . When it is energized via the control box  16 , the brake shoe  34  is pulled to the position indicated by the broken line in  FIG. 3B  and releases locking state of the joint member  31  with respect to the housing  30 . Accordingly, the joint  13   a  is locked in a state in which the electromagnet  37  is not energized, and is unlocked in a state in which the electromagnet  37  is energized.  
         [0041]     In this arrangement, during use, the operator operates the respective operating tabs  35  which are mounted to the respective joints  13   a ,  13   b ,  13   c  first to move a position shown by solid lines in  FIGS. 3A and 3B , where the biasing force of the spring member  36  becomes the maximum value. In this case, the locking force of the joints  13   a ,  13   b ,  13   c  are set to the maximum state.  
         [0042]     In this case, the first and second micro switches  20 ,  21  are both in the OFF state, and hence the brake shoe  34  is pressed against the brake disk  33  by the spring member  36 , whereby the joints  13   a ,  13   b ,  13   c  are locked against rotation by its frictional force. In other words, the arms  12   a ,  12   b , and  12   c , and the supporting base  10  do not move with respect to each other. The ball joint  14  is also locked against movement in the same manner, and the arm  12   a  and the holding device  15  are set to the locked state in which they do not move with respect each other.  
         [0043]     Here, when it is necessary to move the arms  12   a ,  12   b ,  12   c , the operator grips the holding device  15  and presses the first and second switch levers  18 ,  19 . Then, the first and second micro switches  20 ,  21  are turned ON against the biasing forces of the spring members  182 ,  192 , and its ON signal is supplied to the control box  16 . The control box  16  supplies electric power to the respective electromagnets  37  of the joints  13   a ,  13   b ,  13   c  and the electromagnet (not shown) of the ball joint  14 . Accordingly, the respective brake disks  33  of the joints  13   a ,  13   b ,  13   c  are moved to the position indicated by the broken line in  FIG. 3B  by the electromagnetic force of the electromagnet  37 , and hence the frictional force between the brake disk  33  and the brake shoe  34  is removed, so that the locking against the rotation of the respective joints  13   a ,  13   b ,  13   c  is released.  
         [0044]     At the same time, electric power is also supplied to the electromagnet (not shown) of the ball joint  14  so that locking of the ball joint  14  is released. Accordingly, the operator grips the holding device  15 , moves the endoscope  17  (or other medical devices) to a desired position in the operative portion, and fixes the visual field which he or she wants to observe.  
         [0045]     When locking the respective joints  13   a ,  13   b , and  13   c  and the ball joint  14 , the operator loosens the grip of the holding device  15 . Then, the second switch lever  19  having the larger amount of operating force returns to the initial position by the second spring member  192  first, and then, the second micro switch  21  is turned OFF. Then, the control box  16  blocks the power supply to the electromagnets  37  of the joints  13   a ,  13   b ,  13   c . Consequently, the brake shoe  34  is pressed against the brake disk  33  by the biasing force of the spring member  36 , and the joints  13   a ,  13   b ,  13   c  are locked at the rotated positions, respectively.  
         [0046]     At this time, the first switch lever  18  having the smaller amount of operating force does not return and is supported by a finger, the holding device  15  does not move and is held at the initial position. Then, when the operator further loosens the grip of the holding device  15 , the first switch lever  18  having the smaller amount of the operating force is restored to its initial position by the first spring member  182 , whereby the first micro switch  20  is turned OFF. Here, the control box  16  blocks the power supply to the electromagnet (not shown) of the ball joint  14 . Consequently, the ball joint  14  is fixed and locked at its moved position, whereby the position setting of the endoscope  17  is completed.  
         [0047]     In the case where the locking state of the respective joints cannot be released due to power outage or disconnection of the power cable with the endoscope  17  inserted in the operative portion during surgical operation, the operator rotates the operating tabs  35  of the respective joints  13   a ,  13   b ,  13   c . Then the operating tab  35  is moved along the cam  301  to the position indicated by the broken lines in  FIGS. 3A and 3B . Accordingly, the biasing force of the spring member  36  is lowered, the contact pressure between the brake shoe  34  and the brake disk  33  is lowered, the frictional force therebetween is reduced, and the locking forces of the joints  13   a ,  13   b ,  13   c  are set so as to be capable of manual operation. In this case, the amount of locking force (frictional force) between the brake disk  33  and the brake shoe  34  is set to an extent in which the arms  12   a ,  12   b ,  12   c  do not move spontaneously, which is the amount of locking force in which the operator can move the joints  13   a ,  13   b ,  13   c . In this state, the operator adjusts the movement of the arms  12   a ,  12   b ,  12   c  by a force larger than the amount of locking force, whereby the endoscope  17  at the holding device  15  can be withdrawn from the operative portion.  
         [0048]     In this manner, the medical device supporting apparatus is configured in such a manner that the first and second switch levers  18 ,  19  having different amount of operating force are disposed correspondingly, and locking and unlocking of the arms  12   a ,  12   b ,  12   c  and the holding device  15  are performed in conjunction with the operation of the first and second switch levers  18 ,  19 .  
         [0049]     Accordingly, the operator can recognize completion of operation reliably by the switching operation of the first and second switch levers  18 ,  19  being turned off in sequence according to the amount of operation thereof, and thus locking and unlocking operation of the endoscope  17  with high reliability and accuracy can be realized simply and easily.  
         [0050]     More specifically, the second micro switch  21  having a larger amount of operating force is turned OFF first via the second switch lever  19 , and the first switch lever  18  of the first micro switch  20  having smaller amount of operating force does not return, and hence it can be supported by a finger. Therefore, the holding device  15  does not move with respect to the arms  12   a ,  12   b ,  12   c , and a desired visual field of the endoscope (or adjustment of a medical device) can be easily fixed.  
         [0051]     The operating tabs  35  for adjusting the locking force for the joints  13   a ,  13   b ,  13   c  respectively are adapted to be capable of being operable externally. In this arrangement, even when a failure such as disconnection of the cable or power outage happens during surgical operation, since the arms  12   a ,  12   b ,  12   c  can be moved easily by loosening the locking forces of the joints  13   a ,  13   b ,  13   c  by the operating tabs  35  during the surgical operation, movement of the endoscope  17  including retraction can easily be performed, whereby its handling property is improved.  
         [0052]     A second embodiment of the present invention will now be described.  
         [0053]      FIG. 4  and  FIG. 5  show a medical device supporting apparatus according to the second embodiment of the invention, and include an emergency operating device in addition to the aforementioned first embodiment, which is expected to have the same effect as the first embodiment. Therefore, in  FIG. 4  and  FIG. 5 , identical parts to FIGS.  1  to  3  are represented by the identical numerals and detailed description will not be made.  
         [0054]     In other words, for example, the endoscope  17  is detachably inserted into the holding device  15 . At the position of the holding device  15  in the vicinity of the endoscope mounting position, there are provided recessed first and second switch storage portions  151 ,  152  so as to oppose each other, and first and second micro switches  40 ,  41  are stored and disposed in the first and second switch storage portions  151 ,  152  so as to be operated in the opposite direction. The first and second micro switches  40 ,  41  are electrically connected to the control box  16 .  
         [0055]     A switch lever  42  is rotatably provided in the first switch storage portion  151  via a hinge  421  so as to oppose the first micro switch  40 , and a clockwise (the direction to turn ON the first micro switch  40 ) biasing force is exerted to the switch lever  42  via a first spring member  43 . The proximal end of the first spring member  43  is adjustably engaged with the distal end of the operating force adjusting member  44 . The operating force adjusting member  44  is supported at the midsection by the holding device  15  so as to be capable of screw-adjustment, and is operably provided with a final control element  441  at the proximal end so as to project from the holding device. Accordingly, the operating force adjusting member  44  is moved against the first spring member  43  by its rotating operation, and a biasing force of first spring member  43  is variably set to variably set the operating force of the switch lever  42 . That is, the operating force adjusting member  44  is threadingly engaged with the holding device  15  such that it can be rotated to compress (and therefore preload) the first spring member  43 .  
         [0056]     On the other hand, a recessed switch cover  45  is provided on the second switch storage portion  152  via a spring member  46  at the position opposing to the second micro switch  41  so as to be capable of pressing operation.  
         [0057]     The joints  13   a ,  13   b ,  13   c  can be configured as shown in  FIG. 5 , and a pressing force adjusting member  47  is engaged to the other end of the spring member  36  which is engaged with the brake shoe  34  at one end. The pressing force adjusting member  47  is disposed at the joint shaft  32  so as to be capable of moving in the axial direction, and an adjusting screw  48  is adjustably screwed at a predetermined position. The adjusting screw  48  is connected to the revolving shaft of a brake force adjusting drive motor  49  at a proximal end thereof, and when it is rotated by the drive motor  49 , the pressing force adjusting member  47  is moved axially via the adjusting screw  48  according to the direction of rotation. Accordingly, the pressing force adjusting member  47  variably set a biasing force of the spring member  36  according to the moved position thereof to variably set the press-contact force between the brake shoe  34  and the brake disk  33 .  
         [0058]     The drive motor  49  is connected to a motor driver  50  which constitutes the emergency operating device as shown in  FIG. 6  via a wiring cable  51 . The motor driver  50  is provided in the control box  16  for example, and is connected to power supply  53  via an emergency moving switch  52 . Accordingly, when the emergency moving switch  52  in the control box  16  is turned ON, the motor driver  50  receives a supply of ON signal, and outputs a drive signal to the drive motor  49  in response to this ON signal to drive and control the drive motor  49 . Here, the pressing force adjusting member  47  is moved in the direction of  02  axis, the urging force of the spring member  36  is varied according to the moved position thereof, and the press-contact force between the brake shoe  34  and the brake disk  33  is adjusted. For example, the urging force of the spring member  36  of the pressing force adjusting member  47  is the smallest in a state in which the pressing force adjusting member  47  is moved to the position shown by a broken line in  FIG. 5  and accommodates a predetermined failure.  
         [0059]     In the structure describe above, the operator rotates the operating force adjusting member  44  before use, and varies the compression amount of the spring member  43  to adjust the amount of operating force of the switch lever  42  according to the taste of the operator, grips the holding device  15  so that his/her thumb is placed on the switch lever  42  and the first finger is placed to the switch cover  45  for pressing operation. Here, the first and second micro switches  40 ,  41  are turned ON against the urging force of the spring members  43 ,  46 , and the respective ON signal is supplied to the control box  16 . Then, the control box  16  supplies electric power to the electromagnets  37  of the joints  13   a ,  13   b ,  13   c  and the electromagnet (not shown) of the ball joint  14  of the holding device  15  which holds the endoscope  17 , so that the respective joints  13   a ,  13   b ,  13   c  and the ball joint  14  are set to the rotatable state. In this state, the endoscope  17  is moved to a desired position in the operative portion, the visual field to be observed is fixed, and then, a force to grip the switch lever  42  and the switch cover  45  is loosened in the same manner to turn the first and second micro switches  40 ,  41  OFF in sequence, and the respective joints  13   a ,  13   b ,  13   c  and the holding device  15  are movably placed and fixed.  
         [0060]     In this case, the amount of operating force to turn the first micro switch  40  ON is set to a larger value than that of the second micro switch  41 , a force of the thumb is loosened first to turn the first micro switch  40  to OFF. In this case, since the switch cover  45  is not restored and is maintained in a state of being supported by the first finger, the holding device  15  is not moved.  
         [0061]     In contrast, when the amount of operating force to turn the second micro switch  41  ON is set to a value larger than that of the first micro switch  40 , a force of the first finger is loosen first to turn the second micro switch  41  OFF. In this case, the switch lever  42  is not restored and is supported by the thumb. Simultaneously, since the lower side of the holding device  15  is in the state of being supported by fingers other than the thumb and the first finger, the holding device  15  is not moved.  
         [0062]     In the case where the electromagnet cannot be energized due to power outage or disconnection of the power cable during use, the emergency moving switch  52  of the control box  16  is pressed. Then, the ON signal of the emergency moving switch  52  is supplied to the motor driver  50 . The motor driver  50  here drives the drive motors  49  provided in the respective joints  13   a ,  13   b ,  13   c , and moves the pressing force adjusting member  47  to the position indicated by the broken line in  FIG. 5  via the adjusting screw  48 . Accordingly, the biasing force of the spring member  36  is reduced in comparison with the non-failure state, and a contact pressure force to press the brake disk  33  against the brake shoe  34  is set to a smaller value.  
         [0063]     Although the amount of locking force between the brake disk  33  and the brake shoe  34  is maintained in an extent in which the arms  12   a ,  12   b ,  12   c  are not moved spontaneously, but the operator can move the joints  13   a ,  13   b ,  13   c . The operator moves the arms  12   a ,  12   b ,  12   c  by the amount of force larger than that for locking the joints  13   a ,  13   b ,  13   c  to withdraw the endoscope  17  supported by the holding device  15  from the operative poriton.  
         [0064]     According to the second embodiment, since the amount of operating force of the first micro switch  40  is adapted to be selectively variable, the amount of operating force can be set selectively according to the taste of the operator, and hence the handling property can be improved. Also, in this arrangement, even in the case of failure such as disconnection of an electric system such as a power supply system or power outage, the arms  12   a ,  12   b ,  12   c  themselves are prevented from moving spontaneously only by pressing the emergency moving switch  52  and, in addition, the locking force of joints  13   a ,  13   b ,  13   c  can be adjusted to an extent in which the operator can move the arms  12   a ,  12   b ,  12   c . Therefore, quick support in the event of failure is achieved.  
         [0065]     Subsequently, a third embodiment of the present invention will be described.  
         [0066]      FIG. 7  shows a medical device supporting apparatus according to the third embodiment of the present invention, which is expected to have the same effect as the first and second embodiments. Therefore, in  FIG. 7 , identical parts to  FIG. 1  are represented by the identical numerals and detailed description will not be made.  
         [0067]     In other words, the aforementioned arms  12   a ,  12   b ,  12   c  are connected via a joint  60   a , a joint  60   b , and joint  60   c , in which known fluid (pneumatic pressure) brakes are integrated, in sequence. The fluid brake is adapted to release the locking state of the brake when a pressure is applied. The holding device  15  is movable connected to the arm  12   a  via a ball joint  61  in which a fluid (pneumatic pressure) brake is integrated in the same manner. These fluid brakes are connected to a pneumatic pressure control device, described later, which is integrated in a carrier base  62  for supporting the arms  12   a ,  12   b ,  12   c  via piping (not shown).  
         [0068]     The pneumatic pressure control device is configured in such a manner that a fluid pressure source, not shown, such as a gas cylinder provided in a surgical operation room, is connected to an external connector  63 , as shown in  FIG. 8 , and an input end of a check valve  64  is connected to the external connector  63 . The check valve  64  is connected at an output end to an electromagnetic valve  66  via a first regulator  65  for adjusting the pressure, and at the other output end to a second regulator  68  for adjusting the pressure via an air chamber  67 .  
         [0069]     When no input signal is supplied to the electromagnetic valve  66  a first conduit line  66   a  is closed, and a second conduit line  66   b  and a third conduit line  66   c , which is in communication with an exhaust port are communicated, while in a state in which an input signal is supplied thereto, the second conduit line  66   b  and the first conduit line  66   a  are brought into communication. Then, the second conduit line  66   b  of the electromagnetic valve  66  is connected to a conduit line  70  via a first manual valve  69 , and is connected to the fluid brakes integrated in the joints  60   a ,  60   b ,  60   c  via the conduit line  70 .  
         [0070]     The second regulator  68  is connected to the second manual valve  71  to set fluid in the air chamber  67  at a pneumatic pressure providing the locking force to the airbrake to an extent that the arms  12   a ,  12   b ,  12   c  are not moved spontaneously, but may be moved manually by the operator, and output it to the conduit line  70  via the second manual valve  71 .  
         [0071]     The carrier base  62  is provided with carrier wheels  621  at four corners thereof, and for example, two stoppers  622 ,  622  are rotatably provided about a rotary axis  04  via hinges  623 ,  623  at a predetermined distance corresponding to the carrier wheels  621 . The stoppers  622 ,  622  are disposed so as to be selectively rotatable via detent device  624  (in  FIG. 7 , only one of them is shown as a matter of convenience of the drawing).  
         [0072]     The stoppers  622 ,  622  are provided with operating tabs  622   a  at the upper ends thereof as shown in  FIG. 9 , and with contact members  622   b  at the lower end thereof corresponding to the surface of installation such as a floor surface. Threaded portions  622   c  are provided at the midsection of the stopper  622 , and the threaded portions  622   c  are attached to guiding members  622   d  so as to be adjustable by screwing. Accordingly, the stoppers  622 ,  622  are rotated by holding the operating tabs  622   a  by hand, so that the threaded portions  622   c  are moved in the vertical direction by being guided by the guiding members  622   d.    
         [0073]     As shown in  FIG. 10 , the aforementioned holding device  15  is provided with a known photo interrupter  72  instead of the second micro switch  41  in the second embodiment. The photo interrupter  72  has two contact points on the back side thereof, and is adapted in such a manner that the two contact points are electrically short circuited when being touched to detect contact with the operator&#39;s hand.  
         [0074]     The photo interrupter  72  and the first micro switch  40  of the holding device  15  are connected in series to a control circuit of the electromagnetic valve  66 . The control circuit drives the electromagnetic valve  66  in a state in which the photo interrupter  72  and the first micro switch  40  are in the OFF state to supply air to the fluid brakes of the respective joints  60   a ,  60   b ,  60   c , and the ball joint  61 .  
         [0075]     In this arrangement, before performing the surgical operation, an assistant or a nurse releases the detent device  624  of the stopper  622 , and allows rotation about the rotary axis  04  via the hinge  623 . In this state, whether the contact surface of the contact portion  622   b  of the stopper  622  which comes into contact with the floor is dirty is checked. When the contact surface of the contact portion  622   b  is dirty, the contact surface is cleaned in order to secure the fixing force. Then, the carrier base  62  is moved to a desired position using the carrier wheels  621 , where the operating tab  622   a  of the stopper  622  is rotated to cause the contact portion  622   b  to be abutted against the floor. The carrier base  62  is positioned on the floor so as not to move when two of the carrier wheels  621  on the side of the stopper come apart from the floor.  
         [0076]     When the operator grips the holding device  15  in order to move the holding device  15  to a desired position, his/her first finger and second finger touch the photo interrupter  72 , and the photo interrupter  72  detects touch of the fingers. In this state, the operator presses the switch lever  42  with his/her thumb, and turns the first micro switch  400 N. Then, the electromagnetic valve  66  of the aforementioned pneumatic pressure control device is activated and air is supplied to the fluid brakes of the respective joints  60   a ,  60   b ,  60   c  and the fluid brake of the ball joint  61 , so that the brakes of the respective joints  60   a ,  60   b ,  60   c  and the ball joint  61  are released.  
         [0077]     Then, when the holding device  15  is moved to a desired position, the operator loosens a force exerted by his/her thumb to turn the first micro switch  40  OFF. Then, the electromagnetic valve  66  closes the first conduit line  66   a , and air supplied to the fluid brakes is discharged into the atmospheric air through the exhaust port from the third conduit line  66   c , so that the brakes of the respective joints  60   a ,  60   b ,  60   c  and the ball joint  61  are fixed. In this case, although it takes slight time from the timing when the first micro switch  40  is turned OFF to the timing when the respective joints  60   a ,  60   b ,  60   c  and the ball joint  61  are fixed, the holding device  15  does not move because a gravitational force and a supporting force of his/her hand are in balance.  
         [0078]     When a problem occurs in the electric system due to power outage or disconnection of the power supply cable in a state in which the endoscope  17  is inserted into the operative portion during surgical operation, the first manual valve  69  is closed first, and then the second manual valve  71  is opened to supply air to the fluid brakes. Consequently, the locking forces of the brakes of the respective joints  60   a ,  60   b ,  60   c  are such that the arms  12   a ,  12   b ,  12   c  do not move spontaneously, but the operator can move the arms  12   a ,  12   b ,  12   c  by hand. In this state, when the operator moves the arms  12   a ,  12   b ,  12   c , the endoscope  17  of the holding device  15  is withdrawn from the operative portion.  
         [0079]     In this manner, according to the third embodiment, since there is no mechanisms for weakening the locking forces of the brakes provided in the respective joints  60   a ,  60   b ,  60   c , the respective joints  60   a ,  60   b ,  60   c  can be reduced in size. Therefore, since the force of inertia caused by the mass of the joints can be reduced when moving the arms, operability is improved.  
         [0080]     According to the third embodiment, since the switching structure using the first micro switch  40  and the photo interrupter  72  is employed, there is no switching error due to a reaction force of the first micro switch  40 , and hence the switching operation is achieved with high degree of accuracy.  
         [0081]     Furthermore, according to the third embodiment, since the stopper  622  is rotatably provided on the carrier base  62 , and the carrier base  62  is positioned and fixed by the stopper  622 , a constantly high locking force is obtained by rotating the stopper  622  in the reverse direction for cleaning the contact portion  622   b  thereof.  
         [0082]     Subsequently, a fourth embodiment of the present invention will be described.  
         [0083]      FIG. 11  and  FIG. 12  show a medical device supporting apparatus according to the fourth embodiment of the present invention, in which further preferable effects are expected in comparison with the first to third embodiments. Therefore, in  FIG. 11  and  FIG. 12 , identical parts to  FIG. 1  are represented by the identical numerals and detailed description will not be made.  
         [0084]     In the fourth embodiment, the distal portion of the arm  12   a  is attached to the holding unit  15 , to which the endoscope  17  is detachably attached, on the lower side in the direction of a gravitational force (distal to an area of larger cross section  17   a , e.g., a surface on a distal side of the endoscope) via a ball joint  80  so as to be capable of switching between the movable state and the locked state, and so as to be unbalanced with respect to the distal end of the arm  12   a  in the movable state.  
         [0085]     The ball joint  80 , as shown in  FIG. 12 , is attached at the proximal end of a rod  801  to the grip member  81  of the holding device  15  on the lower side in the direction of a gravitational force, and the distal end of the rod  801  is provided with a spherical member  802 . The spherical member  802  is stored in the spherical seat housing  803  so as to be capable of moving and being locked. A pressing member  804  is stored in the spherical seat housing  803  so as to be capable of moving in the directions indicated by arrows A, B against the spherical member  802 . The pressing member  804  is exerted with a biasing force in the direction indicated by the arrow A via a spring member  805 , and a disk member  807  formed of magnetic material is attached to the proximal end thereof via a rod  806 . The disk member  807  is disposed so as to oppose an electromagnet  808  at a predetermined distance.  
         [0086]     The electromagnet  808  is connected to the control box  16  (see  FIG. 11 ), and is driven and controlled via the control box  16 . When the electromagnet  808  is driven via the control box  16 , the electromagnet  808  moves the disk member  807  in the direction of the arrow B against the biasing force of the spring member  805 , bringing the pressing member  804  away from the spherical member  802 , setting the spherical member  802  in the spherical seat housing  803  so as to be capable of moving freely, and setting the distance between the arm  12   a  and the holding device  15  so as to be capable of moving. When the electromagnet  808  is stopped being driven, the electromagnet  808  allows the pressing member  804  to be biased and moved in the direction of the arrow A by the spring member  805 . Accordingly, the pressing member  804  exerts a contact pressure against the spherical member  802  of the ball joint  80 , and the ball joint  80  is positioned at the moved position, so that the arm  12   a  and the holding device  15  are fixed in position.  
         [0087]     Assuming that the mass of the holding device  15  is J, the center of gravity thereof is G, and the length between the center of gravity G and the center position P of the ball joint  80  is L with the endoscope  17  inserted, the holding device  15  is assembled in an unbalanced state in which a moment load of LJ is generated with respect to the center position P depending on the mass J in a state in which the electromagnet  808  is driven and the spherical member is in a free state. The grip member  81  of the holding device  15  is provided with first and second switches  82 ,  83 , which constitute a final control element of the input portion and are operated by different amounts of operating force, and are provided separately on the upper and lower ends in the direction of gravitational direction (corresponding to the direction of insertion of the endoscope  17 ) substantially parallel with each other. The first and second switches are electrically connected to the control box  16 . The first switch  82  having a larger operating force is disposed on the upper side of the grip member  81  of the holding device  15 , and, preferably, set to have the displacement of operation smaller than that of the second switch  83 . The second witch  83  having the smaller operating force and, preferably, set to have a larger displacement in comparison with the first switch  82  is disposed on the lower side of the grip member  81  of the holding device  15 .  
         [0088]     Assuming that the distance between an operating portion S of the second switch  83  and the aforementioned center position P is M, the amount of operating force of the second switch  83  is set to a value smaller than a dropping moment (LJ/M) caused by aforementioned unbalance of the holding device  15 . Accordingly, for example, during operation in the locked state, as an operator  84  gradually reduces the gripping force, the second switch  83  located on the lower side with respect to the gravitational force is in the state of being pressed by the finger of the operator  84  by the aforementioned dropping moment (LJ/M), and hence the first switch  82  is absolutely turned OFF prior to the second switch  83 . Therefore, the operability of the first and second switches  82 ,  83  is enhanced, and hence adjustment of movement of the holding device  15  can be performed with a higher degree of accuracy.  
         [0089]     Now, regarding the first and second switches  82 ,  83 , the effect obtained by setting the amount of operation of the first switch  82  is set to a smaller value than the amount of operation of the second switch  83  will be described. For example, during operation in the locked state, when the operator  84  reduces the griping force gradually, as described above, the first switch  82  of the smaller amount of operation is immediately turned OFF, and thereafter, the second switch  83  is turned OFF, whereby the locking operation of the holding device  15  is completed. Therefore, by setting the amount of operation of the first switch  82  to a value as small as possible, the speed of turning-OFF operation of the first switch  82  is increased, and hence the speed-up of the locking operation is promoted.  
         [0090]     In this arrangement, as regards the first and second switches  82 ,  83 , when the operator  84  grips the grip member  81 , the second switch  83  on the lower side is pressed first to output an ON-signal to the control box  16 , and subsequently, the first switch  82  on the upper side is pressed to output an ON-signal to the control box  16  because of their amount of operating force. In this case, the control box  16  opens the spherical member  802  so as to be capable of moving with respect to the spherical seat housing  803  by driving the electromagnet  808  and attracting the pressing member  804  in the direction of the arrow B against the urging force of the spring member  805 . Accordingly, the holding device  15  is capable of moving three-dimensionally with respect to the arm  12   a , and moves the endoscope  17 , which is inserted into the body cavity for example through an opening provided on the surface of the patient&#39;s body, in a desired position.  
         [0091]     Subsequently, when positioning the endoscope  17 , the operator  84  loosens his/her hand, which is gripping the grip member  81  of the holding device  15 . At this time, the second switch  83  of the grip member  81  of the holding device  15  is released by the amount of operating force smaller than LJ/M, because the second switch  83  is in a state in which the moment load of LJ/M is provided to the operating portion S by the mass of the holding device  15  including the endoscope  17  as described above. In other words, in order to lock the endoscope  17  at a desired position, since the grip member  81  of the holding device  15  tends to drop because of the unbalanced state of the holding device  15 , it is supported by the operating portion S of the second switch  83  on the lower side, and hence the first switch  82  on the upper side is turned OFF first.  
         [0092]     At this time, the control box  16  stops driving the electromagnet  808 . Then, the pressing member  804  of the ball joint  80  is urged in the direction of the arrow A by an urging force of the spring member  805  and is brought into press-contact with the spherical member  802 , whereby the spherical member  802  is positioned with respect to the spherical seat housing  803 , so that the holding device  15  is positioned and locked with respect to the arm  12   a.    
         [0093]     In this manner, in the fourth embodiment, the lower side in the direction of gravitational force of the holding device  15 , which holds the endoscope  17 , is assembled to the arm  12   a , which is provided so as to be capable of moving and locking three-dimensionally, via the ball joint  80 , which is capable of moving and locking, to dispose the holding device  15  in the unbalanced manner in a movable state, and the first and second switches  82 ,  83  operated by different amount of operating force are provided on both sides of the grip member  81  of the holding device  15  in the direction of the gravitational force of the holding device  15 .  
         [0094]     In this arrangement, since the holding device  15  is in the unbalanced state in a state in which the endoscope  17  is moved to a desired position by gripping the grip member  81  of the holding device  15  and moving the same with respect to the arm  12   a , as the operator  84 , griping the grip member  81  so as to prevent from dropping, loosens the gripping force gradually, the first switch  82  is consequently released first, then the second switch  83  is subsequently released. Therefore, the distal end of the endoscope  17  inserted into the holding device  15  is prevented from being displaced, and accurate positioning and locking at a desired position are achieved.  
         [0095]     In this arrangement, the unbalanced structure in which the lower side in the direction of the gravitational force of the holding device  15  according to the fourth embodiment is assembled to the arm  12   a  so as to be capable of moving and locking via the ball joint  80 , and in this movable state, the holding device  15  is supported in the unbalanced manner with respect to the arm  12   a  is also applicable to the first to third embodiments described above, and substantially the same effect can be expected.  
         [0096]     Although the case in which the lower side surface in the direction of the gravitational force of the holding device  15  is attached to the arm  12   a  via the ball joint  80  so that the holding device  15  is disposed in an unbalanced manner in the movable state has been described in the fourth embodiment, it is not limited thereto, and various unbalanced structures may be employed.  
         [0097]     Although the case in which the endoscope is used as the medical device has been described in the respective embodiments, it is not limited thereto, and may be used as a supporting structure for the medical device including various treatment devices, and substantially the same effect can be expected.  
         [0098]     Although the case in which the invention is applied to the three-joint arm structure has been described in the respective embodiments, not limited to the number of arms, it may be applied to various types of arm structures, and substantially the same effects can be expected.  
         [0099]     While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact form described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.