Patent Publication Number: US-2015070019-A1

Title: Control apparatus

Description:
This application claims the benefit of Japanese Patent Application No. 2013-187984, filed on Sep. 11, 2013. The content of the aforementioned patent application is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to control. 
     2. Related Art 
     As a liquid injection apparatus used as a medical instrument, there is a known configuration including a hand piece configured to inject liquid and a control apparatus configured to control an operation of the handpiece. The control apparatus is configured to cause the handpiece to execute and stop injection of liquid in accordance with an input from a user (For Example, JP-A-2012-047071). 
     The configuration of the related art described above is superior configuration which achieves incision and resection without using a knife. The inventors studied about an inspection procedure when starting the usage of the apparatus as described above and have gotten to the invention given below. In addition, a reduction in size, a reduction in cost, resource saving, ease of manufacture, and an improvement of user-friendliness are also required. The inventors have made an attempt to solve these challenges as well. 
     SUMMARY 
     An advantage of some aspects of the invention is to solve at least one of the problems described above, and the invention can be implemented as the following forms. 
     (1) An aspect of the invention provides a control apparatus configured to control a detachable electric instrument is provided. The control apparatus includes: a drive signal output unit configured to output a drive signal to the electric instrument; a relay provided on a sending route of the drive signal; a switching unit configured to output a switching signal that switches the relay between ON and OFF; an inspection signal output unit configured to output an inspection signal that inspects the relay to the sending route in a state in which the electric instrument is not connected; and a blocking determining unit configured to determine whether the inspection signal is blocked by the relay in a state in which the relay is turned OFF by the switching signal. In this configuration, whether a function of blocking the signal is normally operated before connecting the electric instrument is determined, and hence unintentional input of the drive signal to the electric instrument after the electric instrument has connected is avoided. 
     (2) This aspect of the invention is directed to the aspect described above, wherein the electric instrument is a medical instrument, and the inspection signal output unit outputs the inspection signal in a state in which the medical instrument is not connected. In this configuration, unintentional input of the drive signal into the medical instrument is avoided. 
     (3) This aspect of the invention is directed to the aspect described above, wherein the control apparatus includes: a first monitoring unit configured to output a signal indicating a result of monitoring of a voltage upstream of the relay; and a second monitoring unit configured to output a signal indicating a result of monitoring of a voltage downstream of the relay; and the first and second monitoring units output the signals indicating the result of monitoring, and the blocking determining unit is configured to compare a signal output from the first monitoring unit and a signal output from the second monitoring unit. In this aspect, whether the inspection signal is blocked by the relay can be determined in a simple configuration. 
     (4) This aspect of the invention is directed to the aspect described above, wherein the control apparatus includes: an opening determining unit configured to determine whether the inspection signal is passed through the relay in a state in which the relay is turned ON by the switching signal. In this aspect, input of the drive signal into the electric instrument is confirmed. 
     (5) This aspect of the invention is directed to the aspect described above, wherein the opening determining unit is configured to compare a signal output from the first monitoring unit and a signal output from the second monitoring unit. In this aspect, whether the drive signal into the electric instrument is input into the electric instrument is determined in a simple configuration. 
     (6) This aspect of the invention is directed to the aspect described above, wherein the signal output by the first monitoring unit indicates whether the voltage input into the relay is not smaller than a threshold value, the signal output by the second monitoring unit indicates whether the voltage output from the relay is not smaller than the threshold value, the threshold value is set to be a value smaller than the maximum voltage generated by the inspection signal in the case where the inspection signal is output, and the maximum voltage generated by the inspection signal is smaller than the maximum voltage generated by the drive signal. In this aspect, the inspection may be executed by using the inspection signal at a lower voltage than the drive signal. 
     (7) This aspect of the invention is directed to the aspect described above, wherein the threshold value is set to be a value larger than the maximum voltage generated by the drive signal in the case where the drive signal is output. In this aspect, output of the signal more than necessary at the time of output of the drive signal is avoided. 
     (8) Another aspect of the invention provides a control apparatus configured to control the detachable medical instrument is provided. The control apparatus includes: a drive signal output unit configured to output a drive signal to the medical instrument; a relay provided in a sending route of the drive signal; a switching unit configured to output a switching signal that switches the relay between ON and OFF; and an inspection signal output unit configured to output an inspection signal to the relay. The control apparatus may be configured to detect the inspection signal passed through the relay when the inspection signal output unit outputs the inspection signal to the relay in a state in which the relay is turned OFF by the switching signal. In this configuration, the control apparatus can detect if the inspection signal passes through the relay in a state in which the relay provided in the sending route of the drive signal is OFF before connecting the medical instrument. Therefore, unintentional output of the drive signal into the medical instrument is detected. 
     The invention may be implemented in various forms other than those described above. For example, the invention may be implemented in forms such as an inspection method, a program for implementing this method, a storage medium having these programs stored therein. Alternatively, the invention may be implemented in forms of a liquid injection apparatus, a liquid injection method, a medical instrument, and a method of surgical operation provided with the above-described control apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a configuration drawing of a liquid injection apparatus. 
         FIG. 2  is a block diagram illustrating an internal configuration of a control apparatus. 
         FIG. 3  is a flowchart showing a relay inspection process. 
         FIG. 4  is a flowchart showing an opening inspection process. 
         FIGS. 5A to 5D  are graphs showing a waveform in the opening inspection process. 
         FIG. 6  is a flowchart showing a connection inspection process. 
         FIGS. 7A to 7D  are graphs showing a waveform in the connection inspection process. 
         FIGS. 8A to 8D  are graphs showing respective waveform at the time of injection of liquid. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     A first Embodiment will be described.  FIG. 1  illustrates a configuration of a liquid injection apparatus  10 . The liquid injection apparatus  10  is a medical instrument used in a medical organization, and has a function to incise and resect an affected area by injecting liquid toward the affected area. 
     The liquid injection apparatus  10  includes a handpiece  20 , a liquid supply mechanism  50 , a sucking apparatus  60 , a control apparatus  70 , and a liquid container  80 . The liquid supply mechanism  50  and the liquid container  80  are connected to each other by a connecting tube  51 . The liquid supply mechanism  50  and the handpiece  20  are connected to each other by a liquid supply flow channel  52 . The connecting tube  51  and the liquid supply flow channel  52  are formed of a resin. The connecting tube  51  and the liquid supply flow channel  52  may be formed of a material other than the resin (a metal, for example). 
     The liquid container  80  stores normal saline solution. The liquid may be pure water or drug solution instead of the normal saline solution. The liquid supply mechanism  50  supplies liquid sucked from the liquid container  80  via the connecting tube  51  to the handpiece  20  via the liquid supply flow channel  52  by driving a pump integrated therein. 
     The handpiece  20  is an instrument that a user of the liquid injection apparatus  10  operates by holding in his or her hand. The user performs incision or resection of an affected area by injecting the liquid injected intermittently from the handpiece  20  onto the affected area. 
     The sucking apparatus  60  is configured to suck liquid or resected tissue around the injection port  58 . The sucking apparatus  60  and the handpiece  20  are connected to each other by a sucking flow channel  62 . The sucking apparatus  60  sucks an interior of the sucking flow channel  62  constantly while the switch for driving the sucking apparatus  60  is ON. The sucking flow channel  62  penetrates through an interior of the handpiece  20 , and opening in the vicinity of a distal end of an injection tube  55 . 
     The sucking flow channel  62  lays over the injection tube  55  extending from a distal end of the handpiece  20 . Therefore, as illustrated in a drawing viewed in a direction indicated by A in  FIG. 1 , a wall of the injection tube  55  and a wall of the sucking flow channel  62  form concentric cylinders. A flow channel in which a sucked material sucked from a suction port  64  which corresponds to the distal end of the sucking flow channel  62  flows is defined between an outer wall of the injection tube  55  and an inner wall of the sucking flow channel  62 . The sucked material is sucked to the sucking apparatus  60  via the sucking flow channel  62 . 
     The handpiece  20  is a disposable product, and is replaced by a new product at every surgical operation. The liquid supply flow channel  52 , the sucking flow channel  62  and a signal cable  72  (hereinafter, these three are referred to collectively as “cables”) are fixed to the handpiece  20 , and is replaced together with the handpiece  20 . When a new handpiece  20  is used, the handpiece  20  to which cables are connected, and the cables are connected to respective connecting points. 
     When the user turns a foot switch  75  ON in a state in which the cables are connected, the control apparatus  70  sends a drive signal to a pulsation generating unit  30  integrated in the handpiece  20  via the signal cable  72 . The pulsation generating unit  30  generates pulses in a pressure of supplied liquid upon input of the drive signal. With this pulsation, an intermittent injection of the above-described liquid is realized. The pulsation generating unit  30  executes generation of pulses by using expansion and contraction of a piezoelectric element integrated therein. The drive signal is for expanding and contracting the piezoelectric element. 
     However, liquid is injected in the case where the foot switch  75  is turned ON as described above is only in the case where the control apparatus  70  is set to a permission mode. The control apparatus  70  sets itself to either the permission mode or a prohibition mode. Even when the foot switch  75  is turned ON in the case of the prohibition mode, the control apparatus  70  does not drive the pulsation generating unit  30  and the liquid supply mechanism  50 . Therefore, in the case of the prohibition mode, no liquid is injected. 
     A default mode of the control apparatus  70  is the prohibition mode. Transfer to the permission mode is executed only when a relay inspection process (described later in conjunction with  FIG. 3 .) is executed before the connection of the signal cable  72  and the inspection is cleared. The permission mode is maintained until the signal cable  72  is connected after the transfer to the permission mode and then the signal cable  72  is disconnected. 
       FIG. 2  is a block diagram illustrating an internal configuration of the control apparatus  70 , and illustrating a state in which the control apparatus  70  and the handpiece  20  are connected via the signal cable  72 . The control apparatus  70  includes a control unit  90 , an upstream voltage measuring unit  91 , a signal output unit  92 , a relay  93 , and a downstream voltage measuring unit  94 . The relay  93  is an electromagnetic relay, and includes a contact point  96  and a solenoid  97 . 
     The control unit  90  is composed of a microcomputer, and issues an instruction to output a drive signal to the signal output unit  92 . The signal output unit  92  outputs the drive signal upon reception of the instruction. The drive signal output from the signal output unit  92  is input to the relay  93  and the upstream voltage measuring unit  91 . In a state in which the contact point  96  is closed (hereinafter, referred to as “relay  93  is ON”), the drive signal passes through the relay  93  and is input to the pulsation generating unit  30  via the signal cable  72 . 
     The control unit  90  switches the relay  93  between ON and OFF (a state in which the contact point  96  is opened) by inputting a switching signal to the solenoid  97  of the relay  93 . In the permission mode descried above, the relay  93  is maintained at ON and in the prohibition mode, the relay  93  is maintained at OFF. The contact point  96  is a normally-opened contact point. Therefore, the relay  93  is ON in the state in which the switching signal is input, and is OFF in the state in which the switching signal is not input. 
     The upstream voltage measuring unit  91  inputs an upstream measuring signal to the control unit  90 . The upstream measuring signal is a digital signal to be set to a value H if the voltage value upstream of the relay  93  is not smaller than a threshold value, and to a value L if smaller than the threshold value. The expression “upstream of the relay  93 ” means a portion between the signal output unit  92  and the relay  93 . The threshold value is a variable value determined by the control unit  90 . 
     The downstream voltage measuring unit  94  inputs a downstream measuring signal to the control unit  90 . The downstream measuring signal is a digital signal to be set to a value H if the voltage value downstream of the relay  93  (between the relay  93  and the pulsation generating unit  30 ) is not smaller than a threshold value, and to a value L if smaller than the threshold value. The threshold value is a variable value determined by the control unit  90 . 
       FIG. 3  is a flowchart showing a relay inspection process. The relay inspection process is executed by the control unit  90  upon a pressing operation of a setup switch provided on the control apparatus  70  in a state in which the handpiece  20  is not connected to the control apparatus  70  via the signal cable  72 . As will be described later, when the inspection in this process is cleared, the mode is transferred form the prohibition mode to the permission mode. 
     First of all, the threshold value to be used by the upstream voltage measuring unit  91  and the downstream voltage measuring unit  94  is set to a threshold value Th1 for inspection (Step S 100 ). Subsequently, an opening inspection process is executed (Step S 200 ). 
       FIG. 4  is a flowchart showing the opening inspection process. First of all, the relay  93  is set to OFF (Step S 210 ). Subsequently, an inspection signal is output to signal output unit  92  (Step S 220 ). The output inspection signal is input to the upstream voltage measuring unit  91 . Subsequently, whether the upstream measuring signal reaches the value H in a predetermined period is determined (Step S 230 ). 
     A graph of  FIG. 5A  shows a waveform of the inspection signal. In other words, the graph (A) shows a voltage value obtained by the upstream voltage measuring unit  91  in the case where the inspection signal is output. As shown in the graph of  FIG. 5A , the voltage value of the inspection signal is linearly increased from zero to a voltage V1 when the output of the inspection signal starts, and after having reached the voltage V1, is maintained at the voltage V1 for a predetermined period. After an elapse of the predetermined period, the voltage value is linearly decreased to zero. The voltage V1 is larger than the threshold value Th1 as shown in the graph of  FIG. 5A . Maintaining the voltage at V1 for a predetermined period means maintaining the voltage V1 within a predetermined voltage range. 
     A graph of  FIG. 5B  is a graph showing an upstream measuring signal in the case where the inspection signal is output. As shown in the graphs of  FIGS. 5A and 5B , the voltage value of the inspection signal is increased to be values not smaller than the threshold value Th1 between a clock time t1 to a clock time t2. Therefore, the upstream measuring signal becomes the value H in this period. 
     The above-described Step S 230  is a step for confirming whether the output by the signal output unit  92  is normally executed on the basis of the fact that the upstream measuring signal is at the value H during the predetermined period (between the clock time t1 and the clock time t2) and at the value L before the clock time t1 and after the clock time t2 as described above. 
     In the case where the upstream measuring signal is not the value H in the predetermined period (No in Step S 230 ), an output abnormal flag is turned on (Step S 240 ). As a condition to determine YES in Step S 230 , the period during which the upstream measuring signal becomes the value H needs not to be strictly between the clock time t1 and the clock time t2, and a time difference within a predetermined range is allowed. 
     Whether the downstream measuring signal was the value L in the case where the upstream measuring signal becomes the value H in the period between the clock time t1 and the clock time t2 (YES in Step S 230 ) or after the output abnormal flag has been turned on is determined (Step S 250 ). 
     A graph of  FIG. 5C  shows a voltage value obtained by the downstream voltage measuring unit  94  in the case where the inspection signal is output in the opening inspection process. A graph of  FIG. 5D  is a graph showing a downstream measuring signal in the case where the inspection signal is output in the opening inspection process. In the opening inspection process, since the relay  93  is set to OFF, the inspection signal is not input to the downstream voltage measuring unit  94 . 
     Step S 250  described above is a step for determining whether the relay  93  blocks the drive signal normally on the basis of the fact that the upstream measuring signal becomes the value H but the downstream measuring signal is the value L. In the case where the downstream measuring signal becomes the value H even though it is for a short time (No in Step S 250 ), an opening abnormal flag is turned on (Step S 260 ) in order to show the result of inspection that the relay  93  cannot be set to OFF, and the opening inspection process is terminated. Examples of reasons why the relay  93  cannot be set to OFF include welding at the contact point  96 . The process described thus far corresponds to the process as a blocking determining unit. 
     In contrast, in the case where the downstream measuring signal is maintained at the value L (YES in Step S 250 ), the opening inspection process is terminated without turning the opening abnormal flag on. 
     Subsequently, whether the opening inspection is cleared is determined (Step S 300 ). Specifically, in the case where neither the output abnormal flag nor the opening abnormal flag is turned on, it is determined that the opening inspection is cleared. In the case where the opening inspection is cleared (YES in Step S 300 ), a connection inspection process is executed (Step S 400 ). 
       FIG. 6  is a flowchart illustrating the connection inspection process. First of all, the relay  93  is set to ON (Step S 410 ). Subsequently, the inspection signal is output to the signal output unit  92  (Step S 420 ). The inspection signal output here is a signal having the same waveform as that used in the opening inspection process. The processes of Step S 210  and Step S 410  in the control unit  90  correspond to the process of the switching unit. 
     Subsequently, whether the upstream measuring signal becomes the value H is determined (Step S 430 ). In the case where the upstream measuring signal is not the value H (NO in Step S 430 ), an output abnormal flag is turned on (Step S 440 ). The methods and the objects of the steps S 430  and S 440  are the same as those of Steps S 230  and S 240  in the opening inspection process. 
     In the case where the upstream measuring signal becomes the value H (YES in Step S 430 ) or after the output abnormal flag has been turned on, whether the downstream measuring signal becomes the value H is determined (Step S 450 ). 
     A graph of  FIG. 7A  is a graph showing a waveform of the inspection signal, and a graph of  FIG. 7B  is a graph showing an upstream measuring signal in the case where the inspection signal is output. Since the graphs of  FIGS. 7A and 7B  are the same as the graphs of  FIGS. 5A and 5B , detailed description will be omitted. 
     A graph of  FIG. 7C  shows a voltage value obtained by the downstream voltage measuring unit  94  in the case where the inspection signal is output in the connection inspection process. A graph of  FIG. 7D  is a graph showing the downstream measuring signal in the case where the inspection signal is output in the connection inspection process. 
     In the connection inspection process, since the relay  93  is set to ON, the inspection signal is input to the downstream voltage measuring unit  94 . In this manner, since the upstream voltage measuring unit  91  and the downstream voltage measuring unit  94  receive an input of the same signal and are set to have the same threshold value Th1, the upstream measuring signal and the downstream measuring signal become the value H in the same period. 
     Step S 450  described above is a step for determining whether the relay  93  allows the drive signal to pass therethrough normally on the basis of the fact that the downstream measuring signal has the same waveform as the upstream measuring signal. In the case where the downstream measuring signal does not become the value H (No in Step S 450 ), a connection abnormal flag is turned on (Step S 460 ) in order to show the result of inspection that the relay  93  cannot be set to ON, and the connection inspection process is terminated. 
     In contrast, in the case where the downstream measuring signal becomes the value H in the same manner as the upstream measuring signal (YES in Step S 450 ), the connection inspection process is terminated without turning the connection abnormal flag on. 
     Subsequently, whether the connection inspection is cleared is determined (Step S 500 ). Specifically, in the case where both of the output abnormal flag and the connection abnormal flag is not turned on, it is determined that the connection inspection is cleared. In the case where the connection inspection is cleared (YES in Step S 500 ), the threshold value is set to a threshold value Th2 (see  FIGS. 8A to 8D ) (Step S 600 ), and the mode is transferred to the permission mode (Step S 700 ). Finally an instruction is issued to the user to connect the cables (Step S 800 ), and the relay inspection process is terminated. The instruction of connection is achieved by displaying a massage such as “Connect the cables.” on a display provided on the control apparatus  70 . 
     In contrast, in the case where the opening inspection is not cleared (NO in Step S 300 ) or in the case where the connection inspection is not cleared (NO in Step S 500 ), the abnormality is notified to the user (Step S 900 ), the relay inspection process is terminated while maintaining the prohibition mode. Notification of abnormality is executed by displaying a message such as “Send the unit to repair” on the display provided on the control apparatus  70  or outputting a buzzer sound. 
       FIGS. 8A to 8D  show graphs in the case where the drive signal is output in the permission mode. Vertical axes of graphs of  FIGS. 8A to 8D  represent a voltage value obtained by the upstream voltage measuring unit  91 , the upstream measuring signal, a voltage value obtained by the downstream voltage measuring unit  94 , and the downstream measuring signal, respectively. Lateral axes represent time. 
     In the case where the drive signal is output, as shown in the graph of  FIG. 8A , the upstream voltage measuring unit  91  receives an input of the drive signal. Furthermore, since the mode is the permission mode, the relay  93  is set to ON, and hence the downstream voltage measuring unit  94  receives an input of the drive signal as illustrated in the graph of  FIG. 8C . 
     As illustrated in the graphs of  FIGS. 8A and 8C , the voltage value of the drive signal increases and decreases cyclically. Depending on the cyclical increase and decrease of the voltage value, the piezoelectric element integrated in the pulsation generating unit  30  expands and contracts cyclically, whereby intermittent injection of the liquid is achieved. 
     As described above, in the case of the permission mode, the threshold value Th2 is set to the upstream voltage measuring unit  91  and the downstream voltage measuring unit  94 . In other words, when the voltage value of the drive signal reaches Th1 in the permission mode, the upstream voltage measuring unit  91  and the downstream voltage measuring unit  94  output the value H. The threshold value Th2 is a value higher than the maximum value of the normal drive signal. Therefore, when the drive signal is output normally, the upstream measuring signal and the downstream measuring signal are always the value L. In this manner, while the drive signal is output, these signals are maintained at the value L to avoid the application of a load to the control unit  90 . 
     According to the embodiment, whether the control apparatus  70  can block and output the drive signal normally may be inspected before connecting the handpiece  20  to the control apparatus  70 . Furthermore, in the inspection, the upstream voltage measuring unit  91  and the downstream voltage measuring unit  94  output digital signals indicating the result of comparison with respect to the threshold values, and hence the control unit  90  is capable of determining whether the apparatus is normal or abnormal. 
     The invention is not limited to the embodiments, examples, and modifications in this specification and may be implemented in various configurations without departing the scope of the invention. For example, technical characteristics in the embodiments, the examples, and the modifications corresponding to the technical characteristics in the respective embodiments in the respective modes described in the paragraph of the summary may be replaced or combined as needed in order to solve part or entire problem described above or in order to achieve part or entire part of the above-described advantages. The technical characteristics may be eliminated as needed unless otherwise specified to be essential in the specification. For example, the followings are exemplified. 
     The contact point of the relay may be a normally-closed contact point, or may be a type in which the opening and closing of the contact point is switched every time when the current flows. 
     The output of the switching signal may be changed depending on a change of the operation of the relay. 
     The type of the relay may be a solid state relay or a program relay. The solid state relay is not provided with a mechanical contact point. However, the “contact point” of this application is not limited to the mechanical contact point, but also includes a configuration for achieving ON and OFF in the solid state relay. 
     The connection inspection do not have to be executed. 
     The control unit may be determined on the basis of an analogue signal on at least one of the opening inspection and the connection inspection. In this case, the control unit may obtain the voltage values at upstream and downstream of the relay without using the upstream voltage measuring unit and the downstream voltage measuring unit. 
     The inspection signal and the drive signal may be monitored by separate hardware. 
     The waveform of the inspection signal may be changed. For example, the waveform of the inspection signal may be a triangle wave in which the voltage value changes so as to straddle the threshold value. 
     The relay inspection process may be executed after the cables are connected. In this case, the inspection may be performed without departing from a range of voltage value which does not cause a problem even though the drive signal is unintentionally input to the pulsation generating unit. 
     The handpiece and the cables may not be fixed. For example, the cables may be fixed to the control apparatus, the liquid supply mechanism, and the sucking apparatus. 
     At least two of the drive signal output unit configured to output the drive signal, the switching unit configured to output the switching signal for switching ON and OFF of the relay, and the blocking determining unit configured to determine whether the inspection signal is blocked by the contact point may be processed by one CPU. By processing one CPU, a reduction in size or a reduction in cost of the control apparatus may be achieved. The process described above may be performed dispersedly with a plurality of CPUs. By the dispersing process, a load on a single CPU is reduced, so that the high-speed process may be executed. 
     There may be provided with a plurality of the relays, or the plurality of the relays may be connected in series. If there is the plurality of the relays, even though the current of one of the relays cannot be blocked, the current can be blocked with a relay which can block the current. 
     One or the plurality of the relay configured to input the inspection signal may be provided. By providing one relay for inputting the inspection signal, the circuit configuration may be simplified, and the ON and OFF can be switched by the relay which can block the signal and the medical instrument can be used while notifying the fact that one of relay cannot block the current. Therefore, the control apparatus may be applied to emergent therapies. By providing the plurality of the relays configured to input the inspection signal, the control apparatus having higher reliability may be provided. 
     The liquid injection apparatus has been described as the handpiece. However, the liquid injection apparatus may be a liquid injection apparatus used in an endoscope. The liquid injection apparatus does not have to be a disposable product, and may be replaced with a new product at every surgical operation. 
     It is also possible to output the inspection signal for inspecting the relay to the sending route in a state after the liquid injection apparatus and the control apparatus have been connected and the liquid injection apparatus has used and the liquid injection apparatus is not connected, and determine whether the inspection signal is blocked by the contact point in a state in which the relay is turned OFF. Consequently, whether the function to block the signal works normally may be determined before performing the control apparatus for the next time, so that the determination may be omitted and the liquid injection apparatus can be used in an early stage. In addition, abnormality of the control apparatus can be detected in an early stage. 
     The liquid injection apparatus may be used in applications other than the medical instrument. 
     For example, the liquid injection apparatus may be used in a cleaning apparatus configured to clean the stain by injected liquid. 
     The liquid injection apparatus may be used in a drawing apparatus configured to draw a line with injected liquid. 
     The system of the liquid injection may be that using a laser beam. The injection system using the laser beam utilizes a pressure variation generated by irradiating liquid with a laser beam intermittently and gasifies the liquid. 
     The medical instrument of the invention is not limited to the liquid injection apparatus and may be applied to an electric surgical knife, or an ultrasonic surgical knife.