Abstract:
An apparatus for holding a medical device has an arm unit equipped with, for example, a polyarticular arm, which holds the medical device such as endoscope movably in the space. Additionally to a determination unit and a controller, the holding apparatus has an operation unit equipped with a plurality of operation members with which an operator&#39;s operation causes the arm unit to be moved spatially. The determination unit determines whether or not operator&#39;s operations at the plurality of operation members corresponds to an improper state deviating from a properly operated state in which at least two predetermined operation members have been operated within a predetermined period of time which is set to measure simultaneity for operations. If it is determined that the operation is in the improper state, the controller prohibits the arm unit from moving. As long as the operation is proper, the arm unit can be moved.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present application relates to and incorporates by reference Japanese Patent application No. 2004-015671 filed on Jan. 23, 2004. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates to a method and apparatus for removably holding various medical devices such as endoscopes used, for example, during surgical operations in cranial nerve surgery. 
     2. Related Art 
     An apparatus for holding medical devices (medical-device holding apparatus) has been known, which has a polyarticular arm equipped with a holder that holds medical devices and joints equipped with brakes to selectively lock/unlock the turns of the arm. This medical-device supporting apparatus allows the holder to support, for example, an endoscope so that the endoscope is positioned to face a desired portion to be examined of a patient. In this attitude of the holder, the joints are locked to prevent a field of view of the endoscope from deviating outside the portion to be examined. Thus a surgeon is able to concentrate on the surgical operation, without being bothered by positional adjustment operations of the endoscope. 
     Meanwhile, as described in Japanese Patent Publication (unexamined) No. 2002-345831, the medical-device holding apparatus has a grasping member which is used to move the holder (i.e., the endoscope), wherein the grasping member is arranged close to the holder. That is, in order to lock and unlock the brakes in the joints, the grasping member is arranged to substantially be perpendicular to an insertion axis assigned to the endoscope and is equipped two operation switches secured thereon. Thus a surgeon grasps the grasping member and, at the same time, pushes those two operation switches by, usually, the first and middle fingers. This push operation allows the brakes to be activated, so that each joint is released from being locked. In other words, in the condition where both the two operation switches are not pressed at the same time (, or together), each joint will not be released from being fixed. It is therefore possible for a surgeon to worry about erroneous release operations of the brakes during a surgical operation, so that the surgeon can concentrate on the operation. 
     Further, in operating the medical-device holding apparatus, it is required that a surgeon&#39;s touch to the arm will not move the arm under the condition in which the brakes have been locked in the joints. To realize such a situation, a large amount of fixing force should be given to each brake. In contrast, with the arm made free (i.e., the locks are released), it should be constructed such that a medical device that has been held by the apparatus can be moved freely with a light amount of operator&#39;s force. In addition, with taking malfunctions and others of the joints, design is made such that the brakes sustain a certain specific level of braking force to prevent the arm from moving in such malfunction cases. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a method and apparatus holding a medical device, which has the capability of selectively locking and unlocking the joints of an arm unit holding the medical device in a proper manner. 
     As one aspect, the present invention provides an apparatus for holding a medical device, comprising: an arm unit spatially movably holding a single medical device; an operation unit equipped with a plurality of operation members to be operated by an operator to enable the arm unit to move spatially; a determination unit determining whether or not an operator&#39;s operation at the plurality of operation members corresponds to an improper state deviating from a properly operated state in which at least two operation members of the operation members have been operated within a predetermined period of time; and a movement controller prohibiting, in a controlled manner, a spatial movement of the arm unit when the determination unit determines that the operation at the plurality of operation members corresponds to the improper state. 
     For making the arm unit holding the medical device movable, it is required for an operator to operate at least two predetermined operation members among a plurality of operation members secured on an operation unit. Only when a properly operated state is established where the “at least two operation members” are operated within a predetermined period of time (for example, a few seconds), the operator is allowed to move the arm unit, so that the arm unit can be moved to spatially move the medical device such as endoscope at operator&#39;s will. 
     However, the operator&#39;s operation is in the improper state deviating from the “properly operated state,” the arm unit is not allowed to move. In other words, the medical device is not allowed to move spatially; of course, cannot be moved at operator&#39;s will. Hence the medical device is obliged to keep its locked (fixed) state at the same spatial position. The “improper state” includes an “improperly operated state,” in which an operator has not operated the foregoing “at least two operation members” within a predetermined period of time; an “accidentally operated state,” in which only part of the foregoing “at least two operation members” is operated due to, for example, a push from any obstacle; and a “malfunctioning state,” in which a signal resulting from operational failures of the operation unit is outputted from the operation unit, the signal showing a situation where only part of the foregoing “at least two operation members” is operated. Incidentally, though the states deviating from the “properly operated state” includes a “non-operated state,” but this is omitted from the explanations in the present invention, because such a state does not relate to the movement of the arm unit any longer. 
     As another aspect of the present invention, there is provided an apparatus for holding a medical device, comprising: an arm unit spatially holding the medical device; an electric driver spatially moving the medical device and being secured to the arm unit; an operation unit equipped with a plurality of operation members to be operated by an operator to control a spatial movement of the medical device; a determination unit determining whether or not an operator&#39;s operation at the plurality of operation members corresponds to an improper state deviating from a properly operated state in which at least two operation members of the operation members have been operated within a predetermined period of time; and an electric operation controller prohibiting the electric driver from being operated in a controlled manner, in cases where it is determined by the determination unit that the operation is in the improper state. Hence the improper states (i.e., the improperly operated state, accidentally operated state, and malfunctioning state) are found to prohibit the operations of the electronic driver, resulting in that the medical device is locked from its spatial movement. 
     Still, as another aspect of the present invention, there is provided a method for holding a medical device to be spatially movable, the medical device being held by an arm unit by allowing an operator to operate a plurality of operation members, the method comprising steps of: determining whether or not an operator&#39;s operation at the plurality of operation members corresponds to an improper state deviating from a properly operated state in which at least two operation members of the operation members have been operated within a predetermined period of time; and prohibiting, in a controlled manner, a spatial movement of the arm unit when it is determined that the operation at the plurality of operation members corresponds to the improper state. This holding method also copes with the forgoing improper states in the same way as the above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a perspective view showing the configuration of a medical-device holding apparatus according to a first embodiment of the present invention; 
         FIG. 2  is a side view, partly sectioned, showing a holder employed by the holding apparatus in the first embodiment; 
         FIG. 3  is a block diagram of hardware elements of a controller employed by the holding apparatus in the first embodiment; 
         FIG. 4  is a functional block diagram of the controller employed by the holding apparatus in the first embodiment; 
         FIG. 5  is a flowchart showing the operations of the controller; 
         FIG. 6  is a perspective view showing a holder employed by a medical-device holding apparatus in a second embodiment according to the present invention; 
         FIG. 7  is a flowchart showing the operations performed by a controller in the second embodiment; 
         FIG. 8  is a perspective view showing a medical-device holding apparatus in a third embodiment according to the present invention; 
         FIG. 9  shows a block diagram of an electric field-of-view driver according to the third embodiment; 
         FIG. 10  illustrates a block diagram of a control circuit according to the third embodiment; and 
         FIG. 11  is a perspective view indicating a holder adopted by a medical-device holding apparatus according to a modification directed to the third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various embodiments of medical-device holding apparatuses according to the present invention will now be described with reference to the accompanying drawings. 
     First Embodiment 
     Referring to  FIGS. 1-5 , a medical-device holding apparatus according to a first embodiment will now be described. 
     As shown in  FIG. 1 , the medical-device holding apparatus is provided with a support base  11 , a polyarticular arm  12  whose one end is attached to the support base  11 , and a holder  13  sustained at the other end of the polyarticular arm  12 . 
     The support base  10  is detachably attached to an attaching member, such as floor or patient bed. The polyarticular  12  is provided with three arms consisting of first to third arms  12   a - 12   c,  three joints  13   a - 13   c  arranged at one end of the first arm  12   a , between the first and second arms  12   a  and  12   b , and between the second and third arms  12   b  and  12   c , respectively, and a ball joint attached to the top of the third arm  12   c . Therefore, on the support base  10 , the arms  12   a ,  12   b , and  12   c  are connected to each other in this order so that the arms  12   a - 12   c  can be moved rotatably in the three-dimensional space via the joints  13   a ,  13   b , and  13   c . In addition, a pillar  15  is suspended from the ball joint  14  attached to the headmost arm  12   c , and a holder  13  to which a medical device is held is secured to the pillar  15 . 
     The ball joint  14  incorporates a known fluid clutch  28   d  (refer to  FIG. 3 ) that uses fluid, such as air, as a pressure transmission medium. The fluid clutch  28   d  is electrically connected to a control box  16  composing as control means and responds to a command from the control box  16  in such a manner that a clutch portion (i.e. a brake not shown) of the fluid clutch  28   d  are selectively controlled between two states of being clutched and non-clutched. The clutch portion connects both the pillar  15  (that is, the holder  13 ) and the third arm  12   c . Thus, when the clutch portion is in its clutched state, the pillar  15  (holder  13 ) is positionally fixed to the third arm  12   c  (i.e., positionally fixed). In contrast, in cases where the clutch portion is in its non-clutched state, the pillar  15  (i.e., the holder  13 ) will not be positionally fixed to the third arm  12   c , and can be moved freely. To be short, the fluid clutch  28   d  responds to the existence and non-existence of fluid pressure to be supplied so that the holder  13  is positionally fixed to the ball joint  14  or positionally released from being fixed to the ball joint  14  in a selective manner. 
     As described, the holder  13  is coupled with the third arm  12   c  via the ball joint  14  with the fluid clutch  28   d , and can be rotated and moved with suspending from the third arm  12   c  under the fluid clutch  28   d  is unclutched (i.e., released). 
     The fluid clutches  28   a - 28   c  (refer to  FIG. 3 ) employing fluid such as air and having the similar construction and function are incorporated in the joints  13   a - 13   c , respectively, and can selectively be switched between their clutched or non-clutched states in answer to a control signal from the control box  16 . The fluid clutches  28   a - 28   c  are constructed to release the clutch portion in response to an application of pressure. In such a control manner, the first arm  12   a  is able to selectively realize the position-fixed state or position-free state to the support base  11 , the second arm  12   b  to the first arm  12   a , and the third arm  12   c  to the second arm  12   b.    
     On the headmost end of the holder  13 , as shown in  FIGS. 1 and 2 , an endoscope  17  serving as one of medical devices to treat and observe the inside of a patient to be examined is detachably loaded and supported. In  FIG. 1 , a reference P depicts a patient to be observed and treated and by the endoscope  17 . 
     By way of example, the holder  13  is formed into a cuboid-like member having a specific thickness and a section perpendicular to its longitudinal axis formed into a rectangle. This holder  13 , which can be grasped by a user, has switches loaded thereto which can be operated by the user. The size of the cuboid-like member is set to an appropriate amount which makes it possible that the user grasps the member well. 
     On a base-side end of the holder  13 , one end of the foregoing pillar  15  is secured, while at the head-side end, a loading hole is formed therethrough. The endoscope  17  is loaded in the loading hole in a detachable manner. 
     On upper and lower surfaces of the holder  13  are formed a first switch and a second switch  18  and  19 , which serve as input means of operation signals, consist of microswitches, respectively. The upper and lower surfaces are defined as upward and downward surfaces of the holder  13  when an operator can grasp the holder  13  from a direction which makes the endoscope  17  downward, as shown by a chain double-dashed line W in  FIG. 2 . 
     The first and second switches  18  and  19  are formed to provide switch signals to the control box  16  through lead wires respectively connecting to the control box  16 . As will be described later, the control box  16  has the configuration that uses the switch signals to produce control signals in which the states indicated by the switch signals are reflected, the control signals being fed to the fluid clutch  28   d  of the ball joint  14  and the fluid clutches  28   a - 28   c  of the joints  13   a - 13   c.    
     The structures of the first and second switches  18  and  19  will now be described. As illustrated in  FIG. 2 , the first and second switches  18  and  19  are embedded in two locations of the holder  13 ; to be specific, when a user grasps the holder  13 , one switch  18  is located close to the holder near to an endoscope-loading region of the holder  13 , that is, a head-side given position of the holder  13  to which the thumb is approximately touched on the upper surface and the other switch  19  is located at a given position of the holder  13  to which the first finger is approximately touched on the lower surface. The first switch  18  is embedded to have its operating portion opened from the upper surface, whilst the second switch  19  is embedded to have its operating portion opened from the lower surface. 
     More specifically, a first and second concave switch accommodating rooms  20  and  21  are formed at given positions of the holder  13 , which are close to the head thereof. These accommodating rooms  20  and  21  are formed to provide their main opening opened from the upper and lower surfaces of the holder  13 , but are slightly positionally shifted with each other in a longitudinal direction of the holder  13 . In the first and second concave switch accommodating rooms  20  and  21 , the first and second switches  18  and  19  are accommodated with their operating directions upside down with each other. Specifically, in  FIG. 2 , the operating direction to the first switch  18  is a downward direction and that to the second switch  19  is an upward direction. The lead wires of the fist and second switches  18  and  19  are electrically coupled to the control box  16 , respectively. 
     Of the above switch accommodating rooms  20  and  21 , the first switch accommodating room  20  accommodates the first switch  18  together with a switch lever  22  and a hinge  23 , where the switch lever  22  faces the first switch  18  to freely rotate thanks to the hinge  23 . To the switch lever  22  is provided a pushing force via a first spring member  24  in the clockwise in  FIG. 2  (corresponding to a direction that turns the first switch  18  “on”). This first spring member  24  has a base portion engaging with a tip of an operation-force-amount adjusting member  25  in an adjustable fashion. This adjusting member  25  has a middle portion held by holder  13  in a screw-adjustable manner and a base portion to which an operating portion  26  is secured so that the operating portion  26  can be operated. The operating portion  26  is located to protrude from the lower surface of the holder  13 . Accordingly, rotating the adjusting member  25  makes the adjusting member  25  itself advance against the first spring member  24 , whereby the pushing force of this first spring member  24  can be adjusted. An amount of force required to operate the switch lever  22  can be adjusted. 
     As shown in  FIG. 3 , each of the foregoing fluid clutches  28   a - 28   d  is coupled with an electromagnetic valve  29  via a duct PG. The electromagnetic valve  29  is coupled with a fluid-pressure source  29   a , which is for example a gas container placed in an operation room. Hence, responsively to the open and close of the electromagnetic valve  29 , the fluid of a given pressure (e.g., air) is supplied to the fluid clutches  28   a - 28   d , respectively, from the fluid-pressure source  29   a.    
     As shown in  FIG. 3 , the control box  16  is provided with a CPU  30 , in which processing on software executed by the CPU  30  provides desired calculation functions. The calculation part of the control box  16 , however, is not always limited to the computer configuration that uses the CPU, but may be configured into a hardware construction that provides desired functions using logic circuits such as AND and OR circuits. 
     The control box  16  according to the present embodiment is provided with, besides the CPU  30 , peripheral devices including a ROM  31 , RAM  32 , clock circuit  33 , input interface  34 , and output interface  35 , a D/A converter  36  connected to the output interface  35 , and a driver  37 . In the ROM  31 , programs are stored in advance, which are computer-readable and define procedures of calculation for control of the clutches which will be described later. When the CPU  30  is activated, it therefore reads in the programs from the ROM  31 , and executes calculation in sequence based on the procedures defined by the read-in programs. The RAM  32  is a memory temporarily used during the calculation of the CPU  30 . The clock circuit  33  is placed to provide a reference clock signal to the CPU  30 . 
     Connected to the input interface  34  are the first and second switches  18  and  19 , so that on/off information from the switches  18  and  19  is transmitted to the CPU  30 . A control signal produced through the calculation executed by the CPU  30  is sent to the D/A converter  36  via the output interface  35 , thereby being subject to D/A conversion. The resultant control signal is amplified by the driver  37 , and then supplied to the electromagnetic valve  29 . 
     The control box  16  is also provided with, as information means, a buzzer  38  and an LED  39 , which are connected to the CPU  30 . 
     Calculating functions realized by the CPU  30  can be depicted as shown in  FIG. 4 . Concretely, with its software processing, the CPU  30  is able to present the functions for a switch detection circuit “A,” determination circuit “B,” and drive/control circuit “C.” 
     Of these functions, the switch detection circuit “A” detects the on/off states of the first and second switches  18  and  19 , and operates on the basis of the detected results such that it outputs an “on” signal to the drive/control circuit “C,” only when both the first and second switches  18  and  19  are turned “on” almost simultaneously (that is, at the same time or within a predetermined period of time). Responsively to the “on” signal, the drive/control circuit “C” outputs a drive signal to open the electromagnetic valve  29 . When the electromagnetic valve  29  is opened, fluid pressure is applied from the fluid-pressure source  29   a  to the fluid clutches  28   a ,  28   b ,  28   c  and  28   d , thus releasing the fluid clutches  28   a - 28   d . As a result, the joints  13   a - 13   c  and boll joint  14  presents their position-free states, that is, released states from their position-fixed states. 
     Meanwhile, in cases where, of the first and second switches  18  and  19 , either one switch is turned “on” over a predetermined period of time or more, the determination circuit “B” determines that either one switch has been pressed alone, and provides no control signal with the drive/control circuit “C” (i.e., “off” state). That is, the electromagnetic valve  29  becomes its closed sate or keeps its closed state. In this closed state of the electromagnetic valve  29 , no fluid pressure is applied from the fluid-pressure source  29   a  to the fluid clutches  28   a - 28   d , with the result that fluid clutches  28   a - 28   d  are kept clutched, whereby the joints  13   a - 13   c  are kept locked (i.e., in their position-fixed states). 
     The determination circuit “B” has a timer function (realized by a timer BT in  FIG. 4 ) in order to measure a state where either the first or second switch  18  or  19  solely becomes “on” over a predetermined period of time or more. 
     Referring to  FIG. 5 , practical procedures of calculation on the software processing executed by the CPU  30  will now be described. 
     The CPU  30  determines, at step S 1 , whether or not the first switch  18  is in the “on” state. If the determination is NO (that is, the first switch  18  is in the “off” state), the processing in the CPU  30  proceeds to step S 2 , whereat the CPU  30  determines whether or not the second switch  19  is in the “on” state. When the determination is NO (that is, the second switch  19  is in the “off” state), the CPU  30  makes the processing to proceed to step S 3 , where the CPU  30  commands the electromagnetic valve  29  to be or kept “off.” The processing is then made to advance to steps S 4 -S 6  in sequence, where the CPU  30  commands the buzzer  38  to be or kept “off” (step S 4 ), commands the LED  39  to be or kept “off” (step S 5 ), and commands the timer BT to initialize its count (step S 6 ). Then the processing returns to step S 2 . 
     In addition, when it is determined “YES” at step S 1 , the CPU 30  makes the processing to step S 7 , whereat it is further determined whether or not the second switch  19  is in the “on” state. If the determination at step S 7  is “YES,” the processing is shifted to step S 8  to allow the electromagnetic valve  29  to be or kept “on.” The processing is then made to advance to steps S 9 -S 11  in sequence, where the CPU  30  commands the buzzer  38  to be or kept “off” (step S 9 ), commands the LED  39  to be or kept “off” (step S 10 ), and commands the timer BT to initialize its count (step S 11 ). Then the processing returns to step S 2 . 
     Moreover, in cases where it is determined “yes” at step S 2  or “no” at step S 7 , the processing in the CPU 30  is shifted to step S 12 , where it is determined whether or not the timer BT is in operation. The determination at step S 12  reveals the timer BT is not in operation (NO), the processing is shifted to step S 13  to cause the timer BT to start its count operation. The processing at step S 14  is then executed to allow the electromagnetic valve  29  to be “off.” Further, at step S 15 , the buzzer  38  is made or kept “off,” and then, at step S 16 , the LED  39  is made or kept “off,” before returning to step S 1 . 
     In the case that the determination at step S 12  is YES, that is, it is determined at step S 12  if the timer BT is in operation or not, the CPU  30  shifts its operation to step S 17 , where it is determined if or not the timer BT has counted a predetermined period of time (for example, 3 seconds) or more. If YES at step S 17 , the processing at steps S 18 , S 19 , and S 20  is executed in turn. Specifically, the electromagnetic valve  29  is brought into or kept “off” (step S 18 ), the buzzer  38  is turned or kept “on” (step S 19 ), and then the LED  39  is turned or kept “on” (step S 20 ), before returning to step S 2 . 
     In contrast, when it is determined NO at step S 17 , the processing at steps S 14 -S 16  is executed by the CPU  30  as described above. To be specific, the electromagnetic valve  29  is made or kept “off” (step S 14 ), the buzzer  15  is made or kept “off” (step S  15 ), and the LED  39  is made or kept “off” (step S 16 ). 
     Accordingly, through the foregoing processing conducted by the CPU  30 , the control signal supplied to the electromagnetic valve  29  is kept “off,” when either the first or second switch  18  or  19  is turned “on” solely. The electromagnetic valve  29  thus keeps its closed valve state, which keeps the clutched states of the fluid clutches  28   a ,  28   b ,  28   c  and  28   d . Since the joints  13   a ,  13   b  and  13   c  are positionally kept locked (clutched), the polyarticular arm  12  is also positionally kept locked, so that the endoscope  17  is positionally fixed (i.e. the position-fixed state). 
     In addition, during the position-fixed state being kept, the system is able to cope with an operator&#39;s operation that only either the first or second switch  18  or  19  is turned “on” and the “on” state lasts for a predetermined period of time (in the present embodiment, three seconds). Even if such an operation is carried out, the foregoing locked state of the polyarticular arm  12  is kept, while the buzzer  38  honks and the LED  39  flashes. Thus the operator is able to steadily know that the medical-device holding apparatus has failed to release its locked state (i.e., position-fixed state), which requires succeeding necessary operations such as unlocking re-operation. Hence the operator&#39;s operation can be smoothened. 
     Additionally, in cases where the endoscope  17  or polyarticular arm  12  is moved to rotate during a surgical operation, it may happen that the drape is pulled to accidentally push either the first or second switch  18  or  19 . It may also happen that such a rotary operation involves an interference with other devices which may cause only either the first or second switch  18  or  19  to be turned “on” by mistake. Even such situations are caused, the foregoing information means immediately informs the operator of the currently operated state, thereby alleviating the operator from anxiety that the operator should take care of operations at all times. This reduces an operator&#39;s burden on the operations. 
     By the way, the exemplified processing shown in  FIG. 5 , which is executed by the CPU  30 , can further be modified with regard to, for example, the order of on/off determinations for the first and second switches  18  and  19 . The second switch  19  may be subjected to the on/off determination, before that for the first switch  18 . With regard to the buzzer  38  and LED  39  serving as the information means, only one of the buzzer  38  and LED  39  may be employed. 
     Further, a period of time to be measured by the timer at step S 17  cannot always be limited to 3 seconds, but may be a minimum period of time which can sense steadily the state in which “either the first or second switch  18  or  19  is “on”-operated alone. In other words, such a period of time can be defined as a time interval for measuring simultaneity for operator&#39;s operations. Hence, for example, an appropriately selected period of time, such as 1 second, 2 seconds, or 4 seconds, can be adopted, depending on design conditions or other necessary factors. 
     Moreover, as described, in the processing shown in  FIG. 5  conducted by the CPU  30 , the detection is made to recognize the state both the first and second switches  18  and  19  are operated “on” and a span of time from the “on” operation at one switch  18  ( 19 ) to that at the other switch  19  ( 18 ) is within a predetermined period of time. This manner of detection can be applied to detection of malfunctioning states of either the first or second switch  18  or  19 . For example, in cases where either switch is in fault condition due to a fusion-bonded switch contact, the processing shown in  FIG. 5  can also be used for detecting the malfunction. In order to achieve this, the CPU  30  is set to execute the processing shown in  FIG. 5  at specific intervals (for example, at intervals of a few minutes or at a time when the apparatus is activated). Hence, when either the first or second switch  18  or  19  is out of order (in other words, no operation is made but the switch is in the “on” state), this state is detected, resulting in that the buzzer  38  honks and the LED  39  flashes. Using an LED dedicated to this detection, which is different from the LED  39  designated as means to inform the foregoing improperly operated states or accidentally operated states, makes it easier for an operator to immediately recognize the malfunctioning states of the various switches. In this case, of course, either one of the buzzer and LED can be used as informing means. 
     Moreover, signals to be detected at steps S 1 , S 2  and S 7  in  FIG. 5  are not be limited to signals from the first and second switches  18  and  19 , but may be signals from electric circuits electrically connected to these switches, respectively. For instance, in a configuration where a relay is arranged to each of the first and second switches  18  and  19  to provide a switch signal via each relay, a signal outputted from each relay can be an object to be detected. Thus, the object to be detected can be developed to peripheral circuits of the switches, such as relay whose contact is fusion-bonded, which may not be confined to the detection of malfunction of the switch itself. This way of detection can raise reliability for the arm-move prohibiting control. 
     Second Embodiment 
     Referring to  FIGS. 6 and 7 , a second embodiment of the medical-device holding apparatus according to the present invention will now be described. In the second and subsequent embodiments, the configuration elements identical or similar to those in the first embodiment will be referred by the same reference numerals for the sake of simplified or omitted explanations. 
     The configurations in the second embodiment differ from those in the first embodiment in the shape of the holder  13  and the locations of the first and second switches disposed in the holder  13 . In addition, a further difference from the first embodiment is how to escape from a locked state where the joints are locked due to the fact that either the first or second switch is alone operated for a predetermined period of time or more. 
     As shown in  FIG. 6 , in order that the fluid clutches in the joints of the polyarticular arm  12  (arms  12   a - 12   c ) have clutched and unclutched in a selective manner, there are provided two operation switches  3   a  and  3   b  mounted on the holder  13  handled for moving the endoscope  17 . The two operation switches  3   a  and  3   b  are arranged on both sides of the plate-like holder  13  in such a manner that they are located at the same position in the longitudinal direction of the holder  13 . The LED  39  is mounted on the endoscope-side tip of the holder  13 . Incidentally, in the present embodiment, the buzzer is omitted from being arranged. When an operator such as surgeon holds grips the holder  13  to press the two operation switches  3   a  and  3   b  by the thumb and first finger at the same time (simultaneously or almost simultaneously), the fluid clutches operates to release the fixed state of each joint (i.e., unclutched). Thus as long as the two operation switches  3   a  and  3   b  are not pressed at the same time or within a predetermined period of time, each joint will not be from its clutched state. 
     In this medical-device holding apparatus, it may happen that rotating the endoscope  17  or arms  12   a - 12   c  during a surgical operation causes the drape to be tightened or an interference with other equipments, so that the operation switches  3   a  and  3   b  are pressed by mistake. To prevent such situations, the CPU  30  executes the processing according to the flowchart shown in  FIG. 7 . 
     That is, at step S 21  in  FIG. 7 , it is determined whether or not one operation switch  3   a , of the two operation switches  3   a  and  3   b , is in “on.” When this determination shows NO, the processing is shifted to step S 22 , where the other operation switch  3   b  is subjected to the determination whether or not it is made “on.” If the determination at step S 22  is NO, the processing goes to step S 23  to turn or keep the electromagnetic valve  29  “off.” Further, the processing is performed at step S 24  to turn or keep the LED  39  “off” and, at step S 25 , to initialize the timer BT, before returning to step S 21 . 
     Meanwhile when it is determined YES at step S 21 , the processing is shifted to step S 26 , where the determination switch  3   b  is subjected to the determination whether or not it is made “on.” The determination of YES allows the processing to be performed at step S 27 , where the electromagnetic valve  29  is made or kept “on.” Then at step S 28 , the LED  39  is made or kept “off,” and at step S 29 , the timer BT is initialized, before being shifted to step S 21 . 
     In the case of the determination of YES at step S 22  or NO at step S 26 , the processing is shifted to step S 30 , where it is determined whether or not the timer BT is in operation. If the determination is NO (not in operation), the processing at steps S 31  to S 33  is carried out in sequence. The timer BT is started to count the time (step S 31 ), the electromagnetic valve  29  is kept “off” (step S 32 ), and the LED  39  is kept “off” (step S 33 ). Then the processing is made to return to step S 21 . 
     On the other hand, if it is determined “YES” at step S 30 , that is, it is found that the timer BT is in operation, the processing is shifted to step S 34  to further determine whether or not the count of the timer BT shows three seconds (i.e., a predetermined period of time) or more. If the determination at step S 34  is YES, i.e., a period of 3 seconds or more is counted, the processing is carried out such that the electromagnetic valve  29  is in its “off” state (step S 35 ) and the LED  39  is turned “on” (step S 36 ). The processing is then shifted to step S 37  to determine whether or not the operation switches  3   a  and  3   b  both are in their “off” states. If this determination is NO, this termination processing is repeated to wait for a situation where the operation switches  3   a  and  3   b  both become “off.” When both the switches  3   a  and  3   b  are released from being pushed (the determination at step S 37  is YES), the processing escapes from the repeated determinations at step S 37 . The CPU  30  returns the processing to step S 21 . 
     When the determination at step S 34  is NO (i.e. a predetermined period of 3 seconds or more has yet to come), the processing at steps S 32  and S 33  is performed as described before. 
     As a result of the foregoing processing, when either one of the operation switches  3   a  and  3   b  attached to the holder  13  is made “on” and its “on” state lasts for the predetermined period of time (e.g., 3 seconds in the present embodiment, but not limited to this period of time), the electromagnetic valve  29  becomes “off.” The arms  12   a - 12   c  are therefore locked to not allow any moves thereof. At the same time, the LED  39  is turned “on” to notify the surgeon (i.e., operator) that the current operation toward the switches is improper. This locked state can be released only when the switches  3   a  and  3   b  both are made “off,” thanks to the processing at step S 37  in  FIG. 7 . 
     Third Embodiment 
     Referring to  FIGS. 8-10 , a third embodiment of the medical-device holding apparatus according to the present invention will now be described. 
     As shown in  FIG. 8 , a holder  204 , which holds endoscope  17 , is attached to the head-side arm  12   a  via the ball joint  14 . To the holder  204  is attached an electric view-change driver  204   a  which will be described later, which is in charge of changing an observing direction of the endoscope  17  by selectively moving it in the X-axis, Y-axis and Z-axis directions. The electric view-change driver  204   a  is eclectically connected to a foot switch box  206  via a control box  205 . 
     Using  FIGS. 9 and 10 , the holder  204 , control box  205 , and foot switch box  206  will now be described. 
     The control box  205  is provided with, in addition to the foregoing electromagnetic valve  29 , a switch detection circuit  207  and a motor control circuit  208 , wherein the switch detection circuit  207  is electrically connected to the electromagnetic valve  29 . Additionally, electrically connected to the switch detection circuit  207  are a joystick switch  209  and a drive switch  210 , which are equipped in the footswitch box  206 . The joystick switch  209  is provided with a four-way switch which operates to move the endoscope  17  in the upward, downward, and lateral directions. By way of example, the switch detection circuit  207  is functionally configured with the aid of the software processing carried out by a CPU, like the foregoing control box in the first embodiment. 
     The holder  204  is provided with the foregoing first and second switches  18  and  19  and an LED  211 , which are electrically connected with the switch detection circuit  207 . The holder  204  is also provided with an X-axis motor  212 , Y-axis motor  213 , and Z-axis motor  214 , which are all electrically coupled with the motor control circuit  208 . Operator&#39;s operations at the joystick switch  209  allow the motor control circuit  208  to drive the X-, Y- and Z-axes motors  212 ,  213  and  214  mounted in the holder  204  concurrently or selectively so that the view of the endoscope  17  can be moved in a controlled manner. 
     The electric view-change driver  204   a  is structured as schematically shown in  FIG. 9 , in which there are provided with an X-axis housing  212   a , Y-axis housing  213   a , Z-axis housing  214   a . The X-axis housing  212   a  is arranged to engage with an X-axis motor  212  with a motor shaft having a pinion gear  215  at one end thereof. This pinion gear  215  is engaged with an X-axis rack  215   a  slidably formed on the X-axis housing  212   a  in the X-axis direction. 
     The Y-axis housing  213   a  is mounted on the X-axis rack  215   a . The Y-axis housing  213   a  is arranged to engage with a Y-axis motor  213  with a motor shaft having a pinion gear  216  at one end thereof. This pinion gear  216  is engaged with a Y-axis rack  216   a  slidably formed on the Y-axis housing  213   a  in the Y-axis direction. 
     Moreover, the Z-axis housing  214   a  is mounted on the Y-axis rack  216   a . The Z-axis housing  214   a  is arranged to engage with a Z-axis motor  214  with a motor shaft having a pinion gear  217  at one end thereof. This pinion gear  217  is engaged with a Z-axis rack  217   a  slidably formed on the Z-axis housing  214   a  in the Z-axis direction. This Z-axis rack  217   a  finally holds the endoscope  17 , as illustrated in  FIG. 9 . 
     Thus, a surgeon (operator) can grip the holder  204  to push down the first and second switches  18  and  19 , for example, by the thumb and first finger at the same tame or within a predetermined period of time. This push activates, with the aid of the switch detection circuit  207 , the electromagnetic valve  29  to release the fluid clutch of each joint from being clutched. In contradiction to this, in the remaining cases where the first and second switches  18  and  19  are not pushed down at the same time or within the predetermined period of time, unlike the above, the switch detection circuit  207  will not permit each joint to be released from being fixed. Of course, when only one of the two switches  18  and  19  is continuously made “on” the predetermined period of time (e.g., 3 seconds) or more, the switch detection circuit  207  will issue a signal to light up the LED  211  in order to inform the operator about the improper operation, which is similar to that in the second embodiment. 
     This control for the operator&#39;s operations at the two switches  18  and  19  may be realized in the same or similar way as or to the processing based on the flowchart shown in  FIG. 5  or  7 , which can be assigned to the control box  205 . 
     The joystick switch  209  on the footswitch box  206  is operated to decide a direction, information indicative of the decided information being displayed on a monitor M as shown in  FIG. 8 . After the decision of this direction, the drive switch  210  is turned “on,” so that the electric view-change driver  204   a  is driven in response to this instruction. And as long as the joystick switch  209  is operated within a predetermined period of time (for example, 5 seconds) starting from the switch “on” of the drive switch  210 , that is, both the switches  209  and  210  are operated (“on”) within the predetermined period of time in the similar manner to the forgoing, the switch detection circuit  207  and motor control circuit  208  jointly operate to instruct the electric view-change driver  204   a  to drive the X-, Y- and Z-axis motors  212 ,  213  and  214 . 
     However, in the case that only either one of the joystick switch  209  and drive switch  210  is operated (“on”) continuously the predetermined period of time or more, a signal from the switch detection circuit  207  will cause the LED  211  to light to inform an operator of this improper operation. Concurrently, the X-, Y- and Z-axes motors  212 - 214  in the electric view-change driver  204   a  are locked not to be driven, whereby the view will be prohibited from being changed. 
     This control for the operator&#39;s operations at both the joystick switch  209  and the drive switch  210  can also be performed in the same manners as above based on based on the flowchart shown in  FIG. 5  or  7 , which can be assigned to the control box  205 . 
     (Modifications) 
       FIG. 11  shows a modification of the third embodiment, wherein the holder  204  is provided with both the joystick switch  209  and drive switch  210 . Hence an operator can grip the holder  204 , during which time the operator operates both the switches  209  and  210 . In this modification, there is no necessity of employing the footswitch box  206 , thus simplifying the switch constructions. 
     In addition, though the foregoing various embodiments have been described about the construction in which the endoscope serving as the medical device is employed, however, this is not a definitive list. Any other types of medical treatment devices can be used as a medical device, so that the similar advantages to the foregoing can be provided. 
     In each of the foregoing embodiments, the polyarticular arm consisting of three joints has been described, but the number of joints is not confined to three. The polyarticular arm having a desired number of joints can be applied to the present invention to enjoy the foregoing advantages which are characteristic of the present invention. 
     Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of the present invention. Thus the scope of the present invention should be determined by the appended claims. For example, in the third embodiment, the control for locking the electric view-change driver may be reduced in practice solely, separately from the control for lock and unlocking the polyarticular arm.