Patent Publication Number: US-2015073345-A1

Title: Medical instrument

Description:
This application claims the benefit of Japanese Patent Application No. 2013-188138, 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 a technique for a medical instrument for ejecting liquid. 
     2. Related Art 
     A medical instrument that ejects liquid from the injection tube by pressurizing the liquid with a driving unit is known. In such a medical instrument, for example, if bubbles are present in the driving unit, the pressure applied to the liquid by the driving unit is absorbed by the change in the volume of bubbles. Accordingly, there is a problem in that the liquid is not pressurized appropriately. As a technique of detecting bubbles in the liquid, the technique disclosed in JP-A-05-305141 is known. 
     In connection with such a medical instrument, it is an issue to develop a technique of detecting various states of the equipment regardless of the presence of bubbles in the driving unit. 
     In addition, when applying the technique disclosed in JP-A-05-305141 to a liquid ejection device, a sensor that can generate an ultrasonic wave and a sensor that can receive an ultrasonic wave are required. This causes a problem in that the structure is complicated and the cost is high. 
     SUMMARY 
     An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects. 
     (1) An aspect of the invention provides a medical instrument for ejecting liquid. The medical instrument includes: a liquid chamber that contains the liquid; a driving unit that pressurizes the liquid contained in the liquid chamber; and a vibration detector that detects vibration when the driving unit is driven. According to the medical instrument of this aspect, it is possible to detect the vibration when the driving unit vibrates using the vibration detector. Therefore, for example, it is possible to detect the state of the medical instrument using the detected vibration. 
     (2) The medical instrument described above may further include a bubble detector that detects bubbles in the liquid chamber based on the vibration detected by the vibration detector. According to the medical instrument of this aspect, since the bubbles in the liquid chamber are detected based on the vibration detected by the vibration detector, it is possible to detect bubbles with a relatively simple structure. Here, the bubbles include not only spherical gas but also gas that is present separated from the liquid. 
     (3) In the medical instrument described above, the vibration detector may be a sound collection device. According to the medical instrument of this aspect, since the vibration detector is a sound collection device, a simple configuration is possible. 
     (4) In the medical instrument described above, the vibration detector may be a vibration sensor. According to the medical instrument of this aspect, since the vibration detector is a vibration sensor, a simple configuration is possible. 
     (5) In the medical instrument described above, the driving unit may be a piezoelectric element, and the piezoelectric element may function as the vibration detector. According to the medical instrument of this aspect, since the same piezoelectric element can function as the driving unit and the vibration detector, it is possible to simplify the structure. 
     (6) The medical instrument described above may further include a degassing unit that discharges bubbles in the liquid chamber to outside based on a detection result of the bubble detector. According to the medical instrument of this aspect, since the bubbles present in the liquid chamber can be discharged by the degassing unit, the driving unit can pressurize the liquid appropriately. 
     All of the components provided in the medical instrument described above are not essential, and some of the components may be appropriately changed, removed, or replaced with other new components and some of the limitative content may be appropriately deleted in order to solve some or all of the problems described above or to achieve some or all of the effects described in this specification. In addition, in order to solve some or all of the problems described above or to achieve some or all of the effects described in this specification, some or all of the technical features included in the aspect of the invention described above may be combined with some or all of the technical features included in the other aspects of the invention described above to realize an independent aspect of the invention. 
     For example, an aspect of the invention can be implemented as a device including one or more of three elements of the liquid chamber, the driving unit, and the vibration detector. That is, this device may include the liquid chamber, or may not include the liquid chamber. In addition, this device may include the driving unit, or may not include the driving unit. In addition, this device may include the vibration detector, or may not include the vibration detector. The liquid chamber may be configured as a liquid chamber that contains the liquid. The driving unit may be configured as a driving unit that pressurizes the liquid contained in the liquid chamber. The vibration detector may be configured as a vibration detector that detects vibration when the driving unit is driven. For example, such a device can be implemented not only as a medical instrument but also as devices other than the medical instrument. According to such a form, it is possible to solve at least one of the various problems relevant to the miniaturization of a device, low cost, resource saving, ease of manufacture, improvement in usability, and the like. Some or all of the technical features of each aspect of the medical instrument described above can be applied to this device. 
     The invention can also be implemented as various forms other than the device. For example, the invention can be implemented as forms, such as a liquid ejection device, a method of ejecting liquid, a method of manufacturing a liquid ejection device, a bubble detection method, and a bubble discharge method. 
    
    
     
       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 an explanatory diagram illustrating the configuration of a medical instrument. 
         FIG. 2  is a block diagram showing the configuration of a bubble detector. 
         FIG. 3  is a timing chart showing the operation of the bubble detector. 
         FIGS. 4A and 4B  are explanatory diagrams showing the measurement result of a vibration signal. 
         FIG. 5  is a flowchart showing the flow of a degassing process. 
         FIG. 6  is an explanatory diagram showing the configuration of a medical instrument of a second embodiment. 
         FIG. 7  is an explanatory diagram showing the configuration of a medical instrument of a third embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     A. First Embodiment 
     A1. Configuration of Medical Instrument 
       FIG. 1  is an explanatory diagram illustrating the configuration of a medical instrument  10  according to a first embodiment of the invention. The medical instrument  10  is used as a scalpel for incising or resecting the affected part by ejecting liquid to the affected part. 
     The medical instrument  10  includes a liquid ejection device  20 , a liquid supply unit  50 , a liquid container  55 , a control unit  60 , a bubble detector  70 , and a sound collection device  80 . The liquid ejection device  20  and the liquid supply unit  50  are connected to each other through a liquid supply passage  52 . The liquid supply unit  50  and the liquid container  55  are connected to each other through a connection tube  54 . In the present embodiment, the liquid supply passage  52  and the connection tube  54  are formed of resin. 
     The liquid container  55  contains a physiological saline solution as a liquid. As a liquid, it is possible to use various liquids, such as sterile water for medical use or pure water. The liquid supply unit  50  supplies liquid, which is sucked from the liquid container  55  through the connection tube  54 , to the liquid ejection device  20  through the liquid supply passage  52 . 
     The liquid ejection device  20  applies pulsation to the liquid supplied from the liquid supply unit  50 , thereby ejecting pulsed liquid. The user incises or resects the affected part by applying the pulsed liquid ejected from the liquid ejection device  20  to the affected part of the patient. 
     The liquid ejection device  20  includes a first case  31 , a second case  32 , a third case  33 , a piezoelectric element  35 , a reinforcing plate  36 , a diaphragm  37 , and an injection tube  42 . The first case  31  is a cylindrical member. One end of the first case  31  is bonded to the second case  32 . The other end of the first case  31  is closed by the third case  33 . The piezoelectric element  35  is disposed in a space formed inside the first case  31 . 
     The piezoelectric element  35  is a laminated piezoelectric element. One end of the piezoelectric element  35  is fixed to the diaphragm  37  through the reinforcing plate  36 . The other end of the piezoelectric element  35  is fixed to the third case  33 . The diaphragm  37  is formed of a metal thin film, and a peripheral portion of the diaphragm  37  is fixed to the first case  31 . A liquid chamber  38  is formed between the diaphragm  37  and the second case  32 . The volume of the liquid chamber  38  is changed by the driving of the piezoelectric element  35 . 
     A first flow passage  39  for making liquid flow into the liquid chamber  38  is formed in the second case  32 . The first flow passage  39  is connected to the liquid supply passage  52 . The liquid supplied from the liquid supply unit  50  flows into the liquid chamber  38  through the liquid supply passage  52  and the first flow passage  39 . In addition, a second flow passage  40  for discharging the liquid contained in the liquid chamber  38  is formed in the second case  32 . The second flow passage  40  is connected to the injection tube  42 . 
     The control unit  60  controls the overall operation of the medical instrument  10 . A foot switch  62  operated by the user with a foot is connected to the control unit  60 . When the user turns on the foot switch  62 , the control unit  60  controls the liquid supply unit  50  to supply the liquid to the liquid ejection device  20  (liquid chamber  38 ), and transmits a driving signal to the piezoelectric element  35 . When the driving signal is received from the control unit  60 , the piezoelectric element  35  vibrates at a predetermined frequency. When the piezoelectric element  35  vibrates, the volume of the liquid chamber  38  is changed through the diaphragm  37 , and the liquid contained in the liquid chamber  38  is pressurized. Pulsation is applied to the liquid pressurized at a predetermined frequency, and the liquid is ejected outside as a pulsed liquid through the second flow passage  40  and the injection tube  42 . 
     The ejection of pulsed liquid means the ejection of liquid in a state where the flow rate or the flow velocity changes. The ejection of pulsed liquid includes intermittent ejection in which the liquid is ejected while repeating ejection and stopping. However, since it is sufficient that the flow rate or the flow velocity of the liquid is changed, the intermittent ejection does not necessarily need to be adopted. 
     The sound collection device  80  as a vibration detector collects vibration (in the present embodiment, acoustic vibration) generated from the liquid ejection device  20  by the driving of the piezoelectric element  35 . The sound collection device  80  converts the collected vibration into an electrical signal, and inputs the electrical signal to the bubble detector  70  as a vibration signal D 3 . The bubble detector  70  detects the presence of bubbles or the amount of bubbles in the liquid chamber  38  based on the vibration signal D 3 . When the bubble detector  70  detects bubbles in the liquid chamber  38 , the control unit  60  performs a degassing process for discharging the bubbles in the liquid chamber  38  to the outside. The degassing process will be described later. 
     A2. Configuration of a Bubble Detector 
     The details of the configuration and operation of the bubble detector  70  will be described with reference to  FIGS. 2 and 3 .  FIG. 2  is a block diagram showing the configuration of the bubble detector  70 .  FIG. 3  is a timing chart showing the operation of each component provided in the bubble detector  70 . 
     As shown in  FIG. 2 , the bubble detector  70  includes a band pass filter  71 , a peak hold circuit  72 , a delay circuit  73 , a comparator  74 , a reference voltage generator  75 , and a latch  76 . A timing signal D 2  and the vibration signal D 3  are input to the bubble detector  70 . The timing signal D 2  is input to the bubble detector  70  from the control unit  60 . The timing signal D 2  is a binary signal synchronized with a driving signal D 1  that is input from the control unit  60  to the piezoelectric element  35  (refer to  FIG. 3 ). The vibration signal D 3  is input to the bubble detector  70  from the sound collection device  80 . The vibration signal D 3  is a signal obtained when the sound collection device  80  converts the sound generated from the liquid ejection device  20  into an electrical signal. 
     The band pass filter  71  receives the vibration signal D 3 , extracts only a signal of a predetermined frequency band, and inputs the signal to the peak hold circuit  72  as a specific frequency signal D 4 . The peak hold circuit  72  stores the peak value of the specific frequency signal D 4  input from the band pass filter  71 . The peak hold circuit  72  inputs a peak value signal D 6 , which shows the stored peak value of the specific frequency signal D 4  as a voltage value, to the comparator  74 . 
     The comparator  74  compares the peak value signal D 6  input from the peak hold circuit  72  with a predetermined reference voltage value. The reference voltage value is generated by the reference voltage generator  75 , and is input to the comparator  74  as a reference voltage signal D 7 . The comparator  74  compares the voltage value of the peak value signal D 6  with the voltage value of the reference voltage signal D 7 , and outputs the comparison result to the latch  76  as a binary signal (hereinafter, referred to as a comparison signal D 8 ). The comparator  74  sets the value of the comparison signal D 8  to ON when the voltage value of the peak value signal D 6  is higher than the reference signal. 
     The comparison signal D 8  and the timing signal D 2  are input to the latch  76 . The latch  76  reads the value of the comparison signal D 8  at the timing when the timing signal D 2  is ON, and inputs the read value to the control unit  60  as a bubble detection signal D 9 . 
     The delay circuit  73  receives the timing signal D 2  from the control unit  60 . The delay circuit  73  inputs a signal obtained by delaying the timing signal D 2  (hereinafter, also referred to as a clear signal D 5 ) to the peak hold circuit  72 . The peak hold circuit  72  clears the stored peak value of the specific frequency signal D 4  in synchronization with the clear signal D 5 . 
     Here, the vibration signal D 3  will be described. As described above, the vibration signal D 3  is a signal obtained when vibration (in the present embodiment, acoustic vibration) generated from the liquid ejection device  20  by the driving of the piezoelectric element  35  is collected and is converted into an electrical signal by the sound collection device  80 .  FIGS. 4A and 4B  are explanatory diagrams showing the measurement result of the actual vibration signal D 3 .  FIG. 4A  shows the vibration signal D 3  when there are no bubbles in the liquid chamber  38 .  FIG. 4B  shows the vibration signal D 3  when bubbles are present in the liquid chamber  38 . (A-1) and (B-1) in  FIGS. 4A and 4B  show the vibration signal D 3  where the horizontal axis indicates time and the vertical axis indicates amplitude. (A-2) and (B-2) in  FIGS. 4A and 4B  show the vibration signal D 3  where the horizontal axis indicates frequency and the vertical axis indicates amplitude spectrum (sound pressure spectrum). 
     As can be seen from the comparison between (A-1) and (B-1) in  FIGS. 4A and 4B , the peak value of the amplitude of the vibration signal D 3  when bubbles are present in the liquid chamber  38  is larger than that when bubbles are not present in the liquid chamber  38 . In addition, as can be seen from the comparison between (A-2) and (B-2) in  FIGS. 4A and 4B , a large peak (peak P1 in the diagram) is observed in the amplitude spectrum (sound pressure spectrum) of a specific frequency component. In this measurement, the frequency of the peak P1 was 3.7 kHz. Thus, the characteristics of the vibration generated by the liquid ejection device  20  differ depending on the presence of bubbles or the amount of bubbles in the liquid chamber  38 . 
     The bubble detector  70  detects the presence of bubbles or the amount of bubbles in the liquid chamber  38  by detecting the peak P1. Specifically, the bubble detector  70  can detect the presence of bubbles or the amount of bubbles in the liquid chamber  38  by setting the pass band of the band pass filter  71  of the bubble detector  70  to a frequency band including the frequency of the peak P1 and setting the reference voltage input to the comparator  74  to a value by which the peak P1 can be detected. 
     A3. Degassing Process 
     A degassing process performed by the control unit  60  will be described. The degassing process is a process for discharging bubbles present in the liquid chamber  38  to the outside.  FIG. 5  is a flow chart showing the flow of the degassing process. The degassing process starts when the user of the medical instrument  10  turns ON the foot switch  62 . When the degassing process starts, the control unit  60  operates the bubble detector  70  and receives the bubble detection signal D 9  from the bubble detector  70  (step S 102 ). The control unit  60  reads the value of the bubble detection signal D 9  and determines whether or not the ON signal of the bubble detection signal D 9  continues for N periods (step S 104 ). As the period, a period of the vibration signal D 3  is used. N is a value set in the control unit  60  in advance. In the present embodiment, N is determined by measuring the relationship between the presence of bubbles or the amount of bubbles in the liquid chamber  38  and the vibration signal D 3 . 
     When the control unit  60  determines that the ON signal of the bubble detection signal D 9  continues for N periods (step S 104 : YES), the control unit  60  performs a degassing mode operation for a predetermined time (step S 106 ). In the present embodiment, as a degassing mode operation, the control unit  60  controls the liquid supply unit  50  to increase the flow rate of the liquid, which is supplied to the liquid ejection device  20 , from the flow rate of the liquid at the time of normal operation. In addition, the control unit  60  changes the voltage value and the frequency of the driving signal D 1 . As the flow rate of the liquid supplied to the liquid ejection device  20  and the voltage value of the driving signal D 1  applied to the piezoelectric element  35 , values increased within the range where the safe operation is possible are used. Due to the degassing mode operation performed by the control unit  60 , bubbles in the liquid chamber  38  are discharged to the outside. The control unit  60  performs the process of steps S 102  to S 106  repeatedly until the user turns OFF the foot pedal (step S 108 ). 
     As described above, the medical instrument  10  detects the presence of bubbles or the amount of bubbles in the liquid chamber  38  based on the vibration (in the present embodiment, acoustic vibration) generated by the driving of the piezoelectric element  35 . Therefore, it is possible to detect the presence of bubbles or the amount of bubbles in the liquid chamber  38  with a relatively simple configuration, such as the sound collection device  80  and the bubble detector  70 . 
     In the medical instrument  10 , when bubbles are detected, a degassing mode operation is performed to discharge the bubbles from the liquid chamber  38 . Accordingly, the piezoelectric element  35  can pressurize the liquid of the liquid chamber  38  appropriately. Since the bubble detector  70  can be formed by an electrical circuit, it is possible to detect bubbles with a simple configuration and at low cost. 
     B. Second Embodiment 
     A second embodiment of the invention will be described.  FIG. 6  is an explanatory diagram showing the configuration of a medical instrument  10   a  of the second embodiment. The second embodiment is different from the first embodiment in that a vibration sensor  82  is adopted as a vibration detector. Since the other components of the medical instrument  10   a  are the same as those of the medical instrument  10  in the first embodiment, the configuration of the medical instrument  10   a  other than the vibration sensor  82  is omitted. 
     The vibration sensor  82  is fixed to the third case  33 , and detects the vibration of the liquid ejection device  20 . The vibration sensor  82  converts the detected vibration into an electrical signal, and inputs the electrical signal to the bubble detector  70  as a vibration signal D 3   a . In the present embodiment, the vibration sensor  82  is a piezoelectric element. The vibration signal D 3   a  generated by the vibration sensor  82  is the same as the vibration signal D 3  generated by the sound collection device  80  in the first embodiment, and the vibration characteristics differ depending on the presence of bubbles or the amount of bubbles in the liquid chamber  38 . 
     For example, when bubbles are not present in the liquid chamber  38 , a reaction force is received from the liquid in the liquid chamber when the piezoelectric element  35  pressurizes the liquid chamber  38 . Due to the reaction force, strain occurs in the third case  33 , and this appears as a vibration waveform. On the contrary, when bubbles are present in the liquid chamber  38 , the pressure applied to the liquid by the piezoelectric element  35  is absorbed by the change in the volume of bubbles, and the reaction force that the piezoelectric element  35  receives from the liquid is reduced. Accordingly, the strain of the third case  33  is also reduced to change the vibration characteristics. The amount of reduction of the reaction force that the piezoelectric element  35  receives from the liquid changes with the amount of bubbles. In this case, the amount of strain of the third case  33  is also different. 
     In the present embodiment, as in the first embodiment, the vibration characteristics appearing in the vibration signal D 3   a  when bubbles are present in the liquid chamber  38  are detected by the bubble detector  70 . Specifically, the bubble detector  70  can detect the vibration characteristics of the vibration signal D 3   a  when bubbles are present in the liquid chamber  38  by adjusting the pass band of the band pass filter  71  and the voltage value of the reference voltage input to the comparator  74  from the reference voltage generator  75 . The control unit  60  performs a degassing process based on the bubble detection signal D 9  input from the bubble detector  70 . 
     As described above, the medical instrument  10   a  in the second embodiment detects the vibration generated by the driving of the piezoelectric element  35  using the vibration sensor  82 . Therefore, a vibration detector having a relatively simple structure is possible. By adopting the small vibration sensor  82 , it is possible to miniaturize the liquid ejection device  20 . 
     C. Third Embodiment 
     A third embodiment of the invention will be described.  FIG. 7  is an explanatory diagram showing the configuration of a medical instrument  10   b  of the third embodiment. The third embodiment is different from first embodiment in that the piezoelectric element  35  is adopted as a vibration detector. That is, the piezoelectric element  35  has a function as a driving unit and a function as a vibration detector. 
     As shown in  FIG. 7 , a driving signal D 1  is input to the piezoelectric element  35  from the control unit  60 . The piezoelectric element  35  inputs a vibration signal D 3   b  to a bubble detector  70   b . The vibration signal D 3   b  is equivalent to the back electromotive force of the piezoelectric element  35 . A frequency component due to the vibration of the liquid ejection device  20  detected by the piezoelectric element  35  and a frequency component corresponding to the driving signal D 1  are included in the vibration signal D 3   b . The bubble detector  70   b  includes a band pass filter  71   b , and removes the frequency component corresponding to the driving signal D 1  from the vibration signal D 3   b  by adjusting the pass band and extracts the vibration characteristics appearing in the vibration signal D 3   b  when bubbles are present in the liquid chamber  38 . Although the removal of the frequency component corresponding to the driving signal D 1  and the extraction of the vibration characteristics when bubbles are present in the liquid chamber are performed by one band pass filter in the present embodiment, the removal and the extraction may be performed by separate band pass filters. 
     By detecting the vibration characteristics extracted by the band pass filter  71   b , the bubble detector  70   b  can detect bubbles in the liquid chamber  38 . The bubble detector  70   b  inputs a detection result of the bubbles in the liquid chamber  38 , as the bubble detection signal D 9 , to the control unit  60 . The control unit  60  determines the presence of bubbles or the amount of bubbles in the liquid chamber  38  based on the bubble detection signal D 9 , and performs a degassing process. 
     As described above, in the medical instrument  10   b  of the third embodiment, the piezoelectric element  35  has a function as a driving unit and a function as a vibration detector. Therefore, it is possible to miniaturize and simplify the structure of the medical instrument  10   b . In addition, since it is not necessary to prepare a vibration detector separately, it is possible to realize a low cost. 
     D. Modification Examples 
     In addition, the invention is not limited to the above-described embodiments, but various modifications can be made within the scope without departing from the subject matter or spirit of the invention. For example, the following modification examples are also possible. 
     D1. Modification Example 1 
     In the embodiments described above, bubbles in the liquid chamber  38  are detected based on the detected vibration of the liquid ejection device  20 . However, various states of the liquid ejection device  20  can be detected based on the detected vibration of the liquid ejection device  20 . For example, when cracking occurs in a part of the liquid ejection device  20  (for example, the diaphragm  37  or the first case  31 ) or when a water leak occurs due to cracking, the waveform of the detected vibration of the liquid ejection device  20  is different from that in the normal state. For example, when the state of connection between the first flow passage  39  and the liquid supply passage  52  is different from that in the normal state, the waveform of the detected vibration of the liquid ejection device  20  is different from that in the normal state. For example, when a bolt (screw) used in the liquid ejection device  20  is loose, the waveform of the detected vibration of the liquid ejection device  20  is different from that in the normal state. Thus, various states of the liquid ejection device  20  can be detected by comparing the detected vibration of the liquid ejection device  20  with the vibration in the normal state or by analyzing the vibration waveform. The medical instrument  10  may include a state detector that detects various states of the liquid ejection device  20 . The state detector has a function of detecting various states of the liquid ejection device  20  in addition to the function of the bubble detector. 
     When the state detector has detected a change in the state of the liquid ejection device  20  based on the vibration of the liquid ejection device  20 , it is also possible to perform control to stop the operation of the liquid ejection device  20 . 
     D2. Modification Example 2 
     In the embodiments described above, a piezoelectric element is adopted as a vibration sensor. However, it is possible to adopt various vibration sensors that detect the vibration of the liquid ejection device  20 , such as an electrostrictive element or a vibration sensor that emits laser light to the liquid ejection device  20  and detects the vibration of the liquid ejection device  20  from the behavior of reflected light. 
     D3. Modification Example 3 
     In the embodiments described above, as a degassing method, (1) increase in the flow rate of the liquid supplied to the liquid ejection device  20 , (2) increase in the voltage value of the driving signal D 1 , and (3) change of the frequency of the driving signal D 1  are performed. As a degassing method, one or two of the three methods may be adopted, or two or more methods may be combined. Also in these cases, it is possible to discharge bubbles in the liquid chamber  38 . 
     D4. Modification Example 4 
     In the embodiments described above, a piezoelectric element is adopted as a driving unit. However, it is possible to adopt various driving units capable of pressurizing the liquid contained in the liquid chamber, such as an electrostrictive element or a driving motor. 
     D5. Modification Example 5 
     In the embodiments described above, the vibration detector is adopted. However, instead of providing the vibration detector, a degassing instruction may be input to the control unit  60  so that (1) increase in the flow rate of the liquid supplied to the liquid ejection device  20 , (2) increase in the voltage value of the driving signal D 1 , and (3) change of the frequency of the driving signal D 1  are performed for a predetermined time as a degassing mode operation. As a degassing method, one or two of the three methods may be adopted, or two or more methods may be combined. Also in these cases, it is possible to discharge bubbles in the liquid chamber  38 . 
     Although the liquid ejection device has been described in the above embodiments, the invention is not limited to the liquid ejection device. For example, the invention can also be applied to a liquid circulation device from which liquid is discharged and to which the liquid flows. In addition, in the case of a container that contains liquid, the presence of bubbles or the amount of bubbles can be checked by applying vibration to the liquid directly or indirectly and detecting the vibration. Therefore, this is suitable for a medical instrument for which high reliability or safety is required.