Abstract:
An electronic wind instrument includes: a breath pressure detector that detects a breath pressure developed in the instrument by breath blown into the instrument and that outputs a signal corresponding to the detected breath pressure; an adjustment unit providing an air exhaust passage for the breath blown into the instrument, the air exhaust passage being configured to have a variable conductance for air so that a sensitivity of the breath pressure detector relative to an input pressure of the breath blown into the instrument varies; and a controller that sets one or more among a tone, a volume, and a pitch of a sound to be generated by a sound source in accordance with the signal outputted from the breath pressure detector.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to an electronic musical instrument. 
         [0003]    2. Background Art 
         [0004]    Conventional electronic wind instruments that electronically synthesize and output musical notes are a well-known technology. Such electronic wind instruments typically include performance controls and a mouthpiece, and a breath pressure detector (a pressure sensor) is typically built into the mouthpiece. Notes are turned on and off and the volume is controlled according to the values detected by the breath pressure detector. 
         [0005]    In acoustic wind instruments, musical notes are produced as air blown into the instrument exits through a sound-emitting portion (in acoustic wind instruments, the bell portion, for example). In contrast, in electronic wind instruments, musical notes are produced according to values detected by the breath pressure detector, and therefore the instrument does not have to be designed such that air blown into the instrument in order to produce musical notes exits the instrument. 
         [0006]    Nonetheless, a structure (a drain) that allows the air to exit is still typically provided in order to better reproduce the feeling of playing an acoustic instrument (see Japanese Patent Application Laid-Open Publication No. 2009-258750, for example). 
       SUMMARY OF THE INVENTION 
       [0007]    However, if the performer does not blow enough air into the instrument, it is difficult to make the resulting musical notes sufficiently loud. 
         [0008]    The present invention, in at least one aspect, aims to provide an electronic wind instrument that makes it possible to easily control at least one of the volume, pitch, and tone of the musical notes while playing the instrument. Accordingly, the present invention is directed to a scheme that substantially obviates one or more of the above-discussed and other problems due to limitations and disadvantages of the related art. 
         [0009]    Additional or separate features and advantages of the invention will be set forth in the descriptions that follow and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings. 
         [0010]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, in one aspect, the present disclosure provides an electronic wind instrument, including: a breath pressure detector that detects a breath pressure developed in the instrument by breath blown into the instrument and that outputs a signal corresponding to the detected breath pressure; an adjustment unit providing an air exhaust passage for the breath blown into the instrument, the air exhaust passage being configured to have a variable conductance for air so that a sensitivity of the breath pressure detector relative to an input pressure of the breath blown into the instrument varies; and a controller that sets one or more among a tone, a volume, and a pitch of a sound to be generated by a sound source in accordance with the signal outputted from the breath pressure detector. 
         [0011]    In another aspect, the present disclosure provides an electronic wind instrument, including: a breath pressure detector that detects a breath pressure developed in the instrument by breath blown into the instrument and that outputs a signal corresponding to the detected breath pressure; an adjustment unit having a variable conductance for air for the breath blown into the instrument so that a sensitivity of the breath pressure detector relative to an input pressure of the breath blown into the instrument varies; and a controller that sets one or more among a tone, a volume, and a pitch of a sound to be generated by a sound source in accordance with the signal outputted from the breath pressure detector. 
         [0012]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1A  is a plan view of an electronic wind instrument according to Embodiment 1 of the present invention.  FIG. 1B  is a side view of the electronic wind instrument according to Embodiment 1. 
           [0014]      FIG. 2  is a block diagram illustrating a system configuration of the electronic wind instrument according to Embodiment 1. 
           [0015]      FIG. 3A  is a horizontal cross-sectional view illustrating a drain structure of the electronic wind instrument according to Embodiment 1.  FIG. 3B  is a side view of the electronic wind instrument according to Embodiment 1. 
           [0016]      FIG. 4A  is a cross-sectional view of a first drain unit in a closed state.  FIG. 4B  is a cross-sectional view of the first drain unit in an open state. 
           [0017]      FIG. 5  is a graph showing the output from a breath pressure detector as a function of the pressure of the air blown into the electronic wind instrument according to the Embodiment 1 by a performer. 
           [0018]      FIG. 6A  illustrates an outlet of a second drain unit.  FIG. 6B  is a cross-sectional view of the second drain unit in a fully closed state.  FIG. 6C  is a cross-sectional view of the second drain unit in a fully open state. 
           [0019]      FIG. 7  includes graphs of current control patterns as a function of time for three different duty cycles DUTY: high, mid, and low. 
           [0020]      FIG. 8A  illustrates an outlet of a third drain unit.  FIG. 8B  is a cross-sectional view of the third drain unit in a fully closed state.  FIG. 8C  is a cross-sectional view of the third drain unit in a fully open state. 
           [0021]      FIG. 9  is a graph showing the output from a breath pressure detector as a function of the pressure of the air blown into the electronic wind instrument according to the Embodiment 3 by a performer. 
           [0022]      FIG. 10  is a cross-sectional view of an electronic wind instrument according to a comparative example. 
           [0023]      FIG. 11  is a graph showing the output from a breath pressure detector as a function of the pressure of the air blown into the electronic wind instrument according to the comparative example by a performer. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0024]    Embodiments 1 to 3 of the present invention will be described in detail below with reference to the attached drawings. It should be noted that the present invention is not limited to the examples illustrated in the drawings. 
       Embodiment 1 
       [0025]    Next, an embodiment of the present invention will be described with reference to  FIGS. 1A to 5 . First, the device according to the present embodiment will be described with reference to  FIGS. 1A and 1B .  FIG. 1A  is a plan view of an electronic wind instrument  100  according to the present embodiment.  FIG. 1B  is a side view of the electronic wind instrument  100 . 
         [0026]    The electronic wind instrument  100  according to the present embodiment makes it possible to utilize musical performance techniques typically used when playing an acoustic wind instrument. The present embodiment will be described with the electronic wind instrument  100  being a saxophone as an example. However, the present invention is not limited to this example, and the electronic wind instrument  100  may be an electronic version of another woodwind instrument such as a clarinet, a brass instrument, or any other type of wind instrument. 
         [0027]    As illustrated in  FIGS. 1A and 1B , the electronic wind instrument  100  according to the present embodiment includes a body  100   a,  controls  1  on the body  100   a,  a sound system  7 , and a mouthpiece  10 . The electronic wind instrument  100  is shaped like an acoustic saxophone. 
         [0028]    The body  100   a  is shaped like the main body of a saxophone. The controls  1  include performance keys for controlling pitch and the like as well as various settings keys and are operated by the performer&#39;s (the user&#39;s) fingers. The mouthpiece  10  is operated by the performer&#39;s mouth. The sound system  7  includes speakers or the like and outputs musical notes. 
         [0029]    As illustrated in the partial through-view of the electronic wind instrument  100  in  FIG. 1A , a breath pressure detector  2 , a central processing unit (CPU)  3  that functions as a controller, a read-only memory (ROM)  4 , a random-access memory (RAM)  5 , and a sound source  6  are arranged on a substrate  17  arranged inside the body  100   a.  The substrate  17  includes wires that function as a bus  8  and connect together the breath pressure detector  2 , the CPU  3 , the ROM  4 , the RAM  5 , and the sound source  6 . 
         [0030]    The breath pressure detector  2  detects the pressure of the stream of air blown into the mouthpiece  10  by the performer. The sound source  6  is a circuit that generates musical notes. 
         [0031]    Next, the features and configuration of the electronic wind instrument  100  will be described with reference to  FIG. 2 .  FIG. 2  is a block diagram illustrating the system configuration of the electronic wind instrument  100 . 
         [0032]    As illustrated in  FIG. 2 , the electronic wind instrument  100  includes the controls  1 , the breath pressure detector  2 , the CPU  3  that functions as a controller, the ROM  4 , the RAM  5 , the sound source  6 , and the sound system  7 . All of the components of the electronic wind instrument  100  other than the sound system  7  are connected together by the bus  8 . 
         [0033]    The controls  1 , which include the performance keys, the settings keys, and the like receive key operations from the performer, and the resulting operation data is output to the CPU  3 . The settings keys can be used to set the type of wind instrument to emulate, change the pitch according to the key of a song, and fine-tune the pitch. The breath pressure detector  2  detects the pressure of the stream of air blown into the mouthpiece  10  by the performer and outputs the resulting pressure data to the CPU  3 . 
         [0034]    The CPU  3  controls the components of the electronic wind instrument  100 . The CPU  3  loads a specified program from the ROM  4  and runs it using the RAM  5 . The CPU  3  uses the running program to execute various processes. More specifically, the CPU  3  sends musical note generation instructions to the sound source  6  according to the operation data from the controls  1  and the pressure data from the breath pressure detector  2 . 
         [0035]    The ROM  4  is a read-only semiconductor memory and stores various types of data and programs. The RAM  5  is a volatile semiconductor memory and has a working area that temporarily stores data and programs. 
         [0036]    The sound source  6  is a synthesizer that generates musical notes according to musical note generation instructions generated by the CPU  3  on the basis of the operation data from the controls  1  and then outputs the resulting musical note signals to the sound system  7 . The sound system  7  amplifies the musical note signals from the sound source  6  and outputs the resulting signals as musical notes from a built-in speaker. 
         [0037]    Next, the structure of a drain of the electronic wind instrument  100  will be described with reference to  FIGS. 3A and 3B .  FIG. 3A  is a cross-sectional view of the drain structure of the electronic wind instrument  100 .  FIG. 3B  is a side view of the electronic wind instrument  100 . 
         [0038]    As illustrated in  FIG. 3A , the mouthpiece  10  includes an opening  11  onto which the performer&#39;s mouth fits and two openings  12  and  13  on the body  100   a  side. The electronic wind instrument  100  also includes tubes  15  and  16 , the substrate  17 , and a drain unit  20  that functions as an adjustment unit, which are arranged inside the body  100   a.  As illustrated in  FIG. 3B , the electronic wind instrument  100  includes on one side face thereof an outlet  19  that functions as part of the drain unit  20 . 
         [0039]    The breath pressure detector  2  is mounted on the substrate  17 . The breath pressure detector  2  is connected to the opening  12  via the tube  15 . The drain unit  20  is connected to the opening  13  via the tube  16 . The breath pressure detector  2  does not include a structure for exhausting air blown thereinto. The drain unit  20 , however, exhausts air blown into the opening  11  by the performer through the outlet  19 . 
         [0040]    Next, the structure of the drain unit  20  will be described with reference to  FIGS. 4A and 4B .  FIG. 4A  is a vertical cross-sectional view of the drain unit  20  in a closed state.  FIG. 4B  is a vertical cross-sectional view of the drain unit  20  in an open state. 
         [0041]    As illustrated in  FIG. 4A , the drain unit  20  includes a case  22  in which an inlet  21  and the outlet  19  are formed, a first retaining member  23 , a shaft-shaped adjustment member  24  that can move freely inside the case  22  and adjusts the aperture of a path S, and a screw head  19   a . The case  22  includes a hollow cylinder portion and a tapered portion  22   a  connected to the inlet side of the hollow cylinder portion. The inlet  21  is also hollow cylinder-shaped and is connected to the end of the tapered portion  22   a.  In other words, the interior of the case  22  is a shaped like a pipe in which the inner diameter of the pipe decreases moving towards the side from which air is blown in. (Comment: This “pipe” is the portion of the case  22  that becomes narrower moving from the tapered portion  22   a  to the inlet  21 , as illustrated in the figure.) The tube  16  is connected to the inlet  21 . The outlet  19  of the drain unit  20  is arranged on the side of the hollow cylinder portion of the case  22  from which air is exhausted. 
         [0042]    Inside the case  22 , the adjustment member  24  is arranged running in the axial direction, and the first retaining member  23  surrounds and supports the adjustment member  24 . The adjustment member  24  is a shaft on which male threads that function as a first screw portion are formed. The adjustment member  24  includes a tapered portion  24   a  on the inlet side and the screw head  19   a  that has a slot for a slotted screwdriver and functions as a setting member on the outlet side. The screw head  19   a  is not limited to being a screw head for a slotted screwdriver. The first retaining member  23  is fixed to the case  22 , and female threads that function as a second screw portion and fit the male threads formed on the adjustment member  24  are formed in the first retaining member  23 . Therefore, by rotating the screw head  19   a  of the adjustment member  24  using a slotted screwdriver inserted through the outlet  19 , the adjustment member  24  can be moved in the axial direction thereof (left and right in the figure) due to the threading between the female threads of the first retaining member  23  and the male threads of the adjustment member  24 . This movement makes it possible to expand or constrict the flow path from the inlet  21  to the tapered portion  22   a,  thereby making it possible to adjust the amount of air that can flow through the path S. Thus, the conductance of air is adjustable by expanding or constricting the flow path from the inlet  21  to the tapered portion  22   a.  Note that the first screw portion and the second screw portion may be switched. 
         [0043]      FIG. 4A  illustrates the closed state of the drain unit  20 , in which the adjustment member  24  is moved as far as possible to the right side of the figure (that is, towards the inlet  21 ) such that the tapered portions  22   a  and  24   a  are in contact with one another. Here, the adjustment member  24  contacts the inner walls of the case  22  from the inlet  21  to the tapered portion  22   a  with no gaps therebetween, thereby completely sealing shut the path S.  FIG. 4B  illustrates the open state of the drain unit  20 , in which the adjustment member  24  is moved towards the left side in the figure (that is, towards the outlet  19 ). This results in a gap between the adjustment member  24  and the inner walls of the case  22 , thereby opening the path S. When the drain unit  20  is in the open state, air that enters through the inlet  21  proceeds along the path S and then exits through the outlet  19 . As the drain unit  20  is adjusted from the closed state to a completely open state by moving the adjustment member  24  from the inlet  21  side to the outlet  19  side, the amount of air that can flow through the drain unit  20  gradually increases. 
         [0044]    Next, the present embodiment and a comparative example will be described.  FIG. 5  is a graph showing the output from the breath pressure detector  2  as a function of the pressure of the air blown into the electronic wind instrument  100  by the performer.  FIG. 11  is a graph showing the output from a breath pressure detector  2 C as a function of the pressure of the air blown into an electronic wind instrument  200  according to a comparative example as illustrated in  FIG. 10  by the performer. 
         [0045]    As illustrated in  FIG. 10 , the electronic wind instrument  200  includes a breath pressure detector  2 C mounted on a substrate  17 C arranged inside a body  100 C. A mouthpiece  10 C includes an opening  13 C, and the breath pressure detector  2 C is connected to the opening  13 C by a tube  16 C. Air blown into the mouthpiece  10 C is exhausted via an outlet  19 C, which is connected to a drain opening  12 C via a tube  15 C. 
         [0046]    In this way, air blown into the electronic wind instrument  200  by the performer is divided between a path that leads to the breath pressure detector  2 C (a sensor path) and a path that leads to outside of the instrument (a drain path). 
         [0047]    As illustrated in  FIG. 11 , there is a substantially linear relationship between the pressure of the air blown by the performer and the resulting output of the breath pressure detector  2 C. This is because the flow area is substantially constant along the length of the tube  15 C. Each performer is capable of producing a different input pressure. If the breath pressure detector  2 C is tuned to output a maximum output value V 2  when a maximum predicted input pressure P 2  is blown into the instrument, performers that can only produce an input pressure P 1  will not be able to achieve a volume any louder than the volume corresponding to the resulting output value V 1  of the breath pressure detector  2 C. 
         [0048]    When creating musical note generation instructions for the sound source  6 , the CPU  3  increases the volume of the musical notes as the pressure data from the breath pressure detector  2  increases. In at least one aspect of the present invention, the screw head  19   a  is rotated to adjust the position of the adjustment member  24  such that the drain unit  20  is in a sufficiently open state or a fully open state. As illustrated in  FIG. 5 , P 1  is the maximum possible input pressure that can be produced by a first performer, and P 2  is the maximum possible input pressure that can be produced by a second performer. Furthermore, V 2  is the output value of the breath pressure detector  2  corresponding to the maximum volume at which the electronic wind instrument  100  can output musical notes. 
         [0049]    As shown by line C 2  in  FIG. 5 , when the second performer blows air into the mouthpiece  10 , by changing the input pressure from the ambient pressure to P 2 , the second performer can achieve output values ranging from 0 to V 2  from the breath pressure detector  2 . This makes it possible to cover the full range of musical note volumes from 0 to the maximum volume. 
         [0050]    However, if the drain unit  20  is kept in the same open state that produces the line C 2  as described above, because the first performer can only produce input pressures up to P 1 , the first performer will only be able to achieve output values up to V 1  (&lt;V 2 ) from the breath pressure detector  2 . Therefore, the first performer will not be able to play musical notes at the maximum volume. This is the same problem with the control scheme of the electronic wind instrument  200  illustrated in  FIG. 10 . 
         [0051]    Here, however, the screw head  19   a  can be rotated to move the adjustment member  24  towards the inlet  21  side, thereby partially closing the valve and adjusting the drain unit  20  into a more closed state. As shown by line C 1  in  FIG. 5 , this makes it possible to achieve output values from 0 to V 2  from the breath pressure detector  2  by changing the pressure of the air blown into the instrument from the ambient pressure to P 1 , thereby making it possible to cover the full range of musical note volumes from 0 to the maximum volume even with smaller input pressures. 
         [0052]    In the electronic wind instrument  100  according to the present embodiment, the volume of the musical notes does not depend only on the absolute pressure of the air blown into the instrument by the performer and can be adjusted according to the state of the drain unit  20 . Therefore, musical notes can be output at the maximum volume configured for the electronic wind instrument  100  even if the input pressure produced by the performer is relatively low. 
         [0053]    Furthermore, the drain unit  20  includes the case  22  that forms a flow path for the air, the adjustment member  24  that is arranged inside the case  22  and adjusts the aperture of the flow path according to the distance between the adjustment member  24  and the case  22 , the first retaining member  23  that supports the adjustment member  24  and moves the adjustment member  24  according to the rotation setting, and the screw head  19   a  for adjusting the position of the adjustment member  24  inside the case  22 . The screw head  19   a  is set to a rotation setting that positions the adjustment member  24  appropriately for the maximum input pressure that can be produced by the performer. This makes it possible to use a simple structure to implement the adjustment unit for adjusting the flow rate of the exhaust air. 
         [0054]    Furthermore, the adjustment member  24  has male threads, and the first retaining member  23  has female threads that fit the male threads. The screw head  19   a  is formed on the adjustment member  24  and can be rotated to move the adjustment member  24 . This makes it possible to easily use a screwdriver to rotate the screw head  19   a  to a rotation setting appropriate for the maximum input pressure that can be produced by the performer. 
       Embodiment 2 
       [0055]    Next, Embodiment 2 of the present invention will be described with reference to  FIGS. 6A to 6C  and  FIG. 7 .  FIG. 6A  illustrates an outlet  19 A of a drain unit  20 A.  FIG. 6B  is a cross-sectional view of the drain unit  20 A in a fully closed state.  FIG. 6C  is a cross-sectional view of the drain unit  20 A in a fully open state. 
         [0056]    In the present embodiment, the electronic wind instrument  100  according to Embodiment 1 is used, but the drain unit  20  is replaced with the drain unit  20 A. Furthermore, the controls  1  include a setting key (a setting unit) that allows the performer to input a duty cycle DUTY (described in more detail later). Note also that the same reference characters are used to indicate components that are the same as the components used in the electronic wind instrument  100  according to Embodiment 1, and descriptions of those components will be omitted here. 
         [0057]    As illustrated in  FIG. 6B , the drain unit  20 A functions as an adjustment unit and includes a case  22 , a frame  25 , a plunger  26 , and an outlet  19 A. The outlet  19 A of the drain unit  20 A is arranged on the side of a hollow cylinder portion of the case  22  from which air is exhausted. As illustrated in  FIG. 6A , the drain unit  20 A does not include a manually adjustable component such as a screw head. 
         [0058]    Inside the case  22 , the plunger  26  is arranged running in the axial direction, and the frame  25  of a solenoid that functions as a plunger moving member surrounds the plunger  26 . The plunger  26  is a solenoid plunger and includes a tapered portion  26   a  on the inlet side thereof that functions as a constricting portion. The frame  25  is fixed to the case  22  and includes a solenoid coil  25   a.  The frame  25  can move the plunger  26  in the axial direction thereof (left and right in the figure) according to whether a current is flowing through the solenoid coil  25   a.  In other words, when no current is flowing to the frame  25 , the plunger  26  is pushed out to the right by an energizing member (not illustrated in the figure) of the frame  25  and functions as a valve (corresponding to the closed valve state). When current is flowing to the frame  25 , the plunger retracts into the frame  25  (corresponding to the open valve state). The CPU  3  uses pulse width modulation (PWM) to control the current to the frame  25 . Therefore, the drain unit  20 A is also connected to the bus  8  illustrated in  FIG. 2 . 
         [0059]    In this way, the plunger  26  moves to adjust the path that air that enters through the inlet  21  follows before exiting through the outlet  19 A. Moving the plunger  26  makes it possible to adjust (that is, expand or constrict) this path.  FIGS. 6B and 6C  are cross-sectional views taken vertically through the case  22  with the case  22  arranged with the inlet  21  on the right side and the outlet  19 A on the left side. As illustrated in  FIGS. 6B and 6C , the more the plunger  26  is moved towards the inlet  21  side, the narrower the area the path inside of the case  22  becomes. Conversely, the more the plunger  26  is moved towards the outlet  19 A side, the wider the area of the path inside of the case  22  becomes. 
         [0060]      FIG. 6B  illustrates the fully closed state of the drain unit  20 A, in which no current flows to the frame  25  and the plunger  26  is moved as far as possible towards the inlet  21  side such that the tapered portions  22   a  and  26   a  are in contact with one another.  FIG. 6C  illustrates the fully open state of the drain unit  20 A, in which current does flow to the frame  25  and the plunger  26  is moved as far as possible towards the outlet  19 A side. When the drain unit  20 A is in the fully open state, air that enters through the inlet  21  proceeds along the path inside the case  22  and then exits through the outlet  19 A. The plunger  26  moves left and right between these states, and as the amount of time the plunger  26  spends in the fully open state relative to the total cycle period increases (that is, as the duty cycle DUTY increases), the flow rate of air through the drain unit  20 A increases. 
         [0061]    Next, control of musical notes according to the input pressure will be described with reference to  FIG. 7 .  FIG. 7  includes graphs of current control patterns as a function of time for three different duty cycles DUTY: high, mid, and low. 
         [0062]    When creating musical note generation instructions for the sound source  6 , the CPU  3  increases the volume of the musical notes as the pressure data from the breath pressure detector  2  increases and also controls the PWM signal sent to the drain unit  20 A according to the duty cycle DUTY input using the controls  1 . 
         [0063]    Next, consider a third, fourth, and fifth performer, each capable of producing a higher maximum input pressure than the last. The fifth performer produces the highest maximum input pressure, and therefore this performer will be able to produce musical notes at the maximum volume even if the ratio of the amount of time the drain unit  20 A spends in the fully open state is relatively high. For performers who, like the fifth performer, can produce a sufficiently high maximum input pressure, the duty cycle DUTY is set to high using the controls  1 . In this case, the CPU  3  detects from the operation data from the controls  1  that the duty cycle DUTY was set to high and generates a PWM signal that controls the current flowing to the frame  25  of the drain unit  20 A such that the high duty cycle DUTY shown in  FIG. 7  is achieved. In the high duty cycle DUTY, the ratio of time that the drain unit  20 A spends in the fully open state relative to the total cycle period is high, thereby making it possible for a large amount of air to flow through the drain unit  20 A. Performers capable of producing the same maximum input pressure as the fifth performer can change the input pressure blown into the instrument to change the output values from the breath pressure detector  2 , thereby making it possible to cover the full range of musical note volumes from 0 to the maximum volume when playing the electronic wind instrument  100  that includes the drain unit  20 A. 
         [0064]    For performers who, like the fourth performer, are capable of producing a medium maximum input pressure, the duty cycle DUTY is set to mid using the controls  1 . In this case, the CPU  3  detects from the operation data from the controls  1  that the duty cycle DUTY was set to mid and generates a PWM signal that controls the current flowing to the frame  25  of the drain unit  20 A such that the mid duty cycle DUTY (which is shorter than the high duty cycle) shown in  FIG. 7  is achieved. In the mid duty cycle DUTY, the ratio of time that the drain unit  20 A spends in the fully open state relative to the total cycle period is of a medium magnitude (and lower than in the high duty cycle), thereby making it possible for a medium amount of air to flow through the drain unit  20 A. Performers capable of producing the same maximum input pressure as the fourth performer can change the input pressure blown into the instrument to change the output values from the breath pressure detector  2 , thereby making it possible to cover the full range of musical note volumes from 0 to the maximum volume when playing the electronic wind instrument  100  that includes the drain unit  20 A. 
         [0065]    For performers who, like the third performer, are capable of producing a low maximum input pressure, the duty cycle DUTY is set to low using the controls  1 . In this case, the CPU  3  detects from the operation data from the controls  1  that the duty cycle DUTY was set to low and generates a PWM signal that controls the current flowing to the frame  25  of the drain unit  20 A such that the low duty cycle DUTY (which is shorter than the mid duty cycle) shown in  FIG. 7  is achieved. In the low duty cycle DUTY, the ratio of time that the drain unit  20 A spends in the fully open state relative to the total cycle period is low (lower than in the mid duty cycle), thereby only allowing a small amount of air (less than in the mid duty cycle) to flow through the drain unit  20 A. Performers capable of producing the same maximum input pressure as the third performer can change the input pressure blown into the instrument to change the output values from the breath pressure detector  2 , thereby making it possible to cover the full range of musical note volumes from 0 to the maximum volume when playing the electronic wind instrument  100  that includes the drain unit  20 A. 
         [0066]    As described above, in the present embodiment the drain unit  20 A includes the case  22  that forms a flow path for the air, the plunger  26  that is arranged inside the case  22  and adjusts the flow path according to the distance between the plunger  26  and the case  22 , and the frame  25  to which current is supplied to move the plunger  26 . This makes it possible to easily use the controls  1  to set a duty cycle DUTY appropriate for the maximum input pressure that can be produced by the performer and also makes it possible to use a simple structure to implement the adjustment unit for adjusting the flow rate of the exhaust air. 
         [0067]    Furthermore, the CPU  3  generates a PWM signal that controls the current flowing to the frame  25  according to the maximum input pressure setting configured for the performer. This makes it possible to reduce power loss resulting from moving unnecessary current to the frame  25 . Moreover, in the present embodiment the PWM control signal has two values: on and off. However, the present embodiment is not limited to this example, and the PWM control signal may include three or more values corresponding to intermediate states of openness of the drain unit  20 A in addition to the fully closed and fully open states. Furthermore, when using a multivalued PWM control signal that include two or more values, the most closed state of the drain unit  20 A represented by the values does not necessarily have to be a fully closed state. 
       Embodiment 3 
       [0068]    Next, Embodiment 3 of the present invention will be described with reference to  FIGS. 8A to 8C  and  FIG. 9 .  FIG. 8A  illustrates an outlet  19 B of a drain unit  20 B.  FIG. 8B  is a cross-sectional view of the drain unit  20 B in a fully closed state.  FIG. 8C  is a cross-sectional view of the drain unit  20 C in a fully open state. 
         [0069]    In the present embodiment, the electronic wind instrument  100  according to Embodiment 1 is used, but the drain unit  20  is replaced with the drain unit  20 B. Note also that the same reference characters are used to indicate components that are the same as the components used in the electronic wind instrument  100  according to Embodiment 1, and descriptions of those components will be omitted here. 
         [0070]    As illustrated in  FIG. 8B , the drain unit  20 B functions as an adjustment unit and includes a case  22 , a fixed guide  27  that functions as a support, a spring  28  that functions as an energizing member, a movable valve  29  that functions as an adjustment member, and an outlet  19 B. The outlet  19 B of the drain unit  20 B is arranged on the side of a hollow cylinder portion of the case  22  from which air is exhausted. As illustrated in  FIG. 8A , the outlet  19 B does not include a component such as a screw head that the performer can adjust manually. 
         [0071]    Inside the case  22 , the fixed guide  27  is arranged running in the axial direction and is fixed to the case  22 . The fixed guide  27  includes a second support  27   a,  and the spring  28  is arranged surrounding the second support  27   a.  The movable valve  29  is arranged on the inlet-side end of the second support  27   a  of the fixed guide  27 . The movable valve  29  can move in the axial direction and has a tapered shape. The movable valve  29  can be moved in the axial direction (left and right in the figure) according to the pressure of the air blown into the instrument. 
         [0072]      FIG. 8B  illustrates the drain unit  20 B with the path S in a fully closed state, in which the input pressure is the ambient pressure (that is, the performer is not blowing air into the electronic wind instrument  100 ) and the energy stored in the spring  28  moves the movable valve  29  into contact with the tapered portion  22   a.    FIG. 8C  illustrates the drain unit  20 B in an open state, in which the performer is blowing air into the electronic wind instrument  100 , thereby opposing the energy stored in the spring  28  and moving the movable valve more towards the inlet  21  side by an amount that corresponds to the input pressure. In the input pressure range from ambient pressure to PT, the spring  28  pushes the movable valve  29  away from the fixed guide  27  and towards the inlet side, thereby bringing the movable valve  29  into contact with the tapered portion  22   a  and putting the drain unit  20 B in the fully closed state. Starting from this state, as the input pressure is increased, the movable valve  29  is pushed towards the fixed guide  27  and the air flow path (the aperture of the valve) widens, eventually bringing the drain unit  20 B into the fully open state when the input pressure P 4  is reached. 
         [0073]    Next, control of musical notes according to the input pressure will be described with reference to  FIG. 9 .  FIG. 9  is a graph showing the output from the breath pressure detector  2  as a function of the pressure of the air blown into the electronic wind instrument  100  according to the present embodiment by the performer. 
         [0074]    When creating musical note generation instructions for the sound source  6 , the CPU  3  increases the volume of the musical notes as the pressure data from the breath pressure detector  2  increases. As illustrated in  FIG. 9 , for input pressures from ambient pressure to PT, the force of the spring  28  is greater than or equal to the force created by the input pressure that attempts to move the movable valve  29  towards the outlet  19 B side, and the drain unit  20 B remains in the fully closed state. Therefore, the relationship between the input pressure produced by the performer and the output from the breath pressure detector  2  is substantially linear and exhibits the same slope as line C 1  in  FIG. 5 . Once the input pressure exceeds PT, the force created by the input pressure that attempts to move the movable valve  29  towards the outlet  19 B side becomes greater than the force of the spring  28 , and therefore the movable valve  29  moves towards the outlet  19 B side, opening a path S. As a result, in comparison to the input pressure region up to PT, the increase in the output of the breath pressure detector  2  for a given increase in the input pressure becomes smaller, as does the resulting increase in volume. Therefore, when the input pressure reaches P 3 , the output of the breath pressure detector  2  is V 3 , which is less than the maximum value MAX that would have been achieved at P 3  if the drain unit  20 B had remained in the fully closed state. As the input pressure increases from P 3  to P 4 , the spring  28  continues to be compressed and resists further compression more strongly. Therefore, the increase in the aperture of the path S due to movement of the movable valve  29  as well as the increase in the output of the breath pressure detector  2  for a given increase in the input pressure becomes smaller, as does the resulting increase in volume. As a result, even at relatively high input pressures, the volume continues to increase according to increases in the output of the breath pressure detector  2  due to increases in the input pressure, thereby making it possible to better simulate the feeling of playing an acoustic wind instrument. 
         [0075]    In this way, even a sixth performer who is only capable of producing a relatively low maximum input pressure (such as P 3 ) can still easily play musical notes at a sufficiently loud volume corresponding to the output value V 3 , which is close to the maximum output MAX. Meanwhile, starting from the fully closed state of the drain unit  20 B, a seventh performer who is capable of producing a high maximum input pressure (such as P 4 ) can gradually increase the input pressure from 0 to play at a volume that follows the same slope as the line C 1  in  FIG. 5 . Once the input pressure exceeds PT, the drain unit  20 B starts to open and the slope of the volume curve begins to decrease. As the seventh performer continues to increase the input pressure, the output of the breath pressure detector  2  more gradually approaches the maximum value until the input pressure reaches P 4 , at which the maximum output from the breath pressure detector  2  is achieved. Therefore, by changing the input pressure blown into the instrument, the seventh performer can achieve output values ranging from 0 to the maximum value from the breath pressure detector  2 , thereby making it possible to cover the full range of musical note volumes from 0 to the maximum volume. 
         [0076]    In the present embodiment as described above, the electronic wind instrument  100  includes the breath pressure detector  2  that detects the pressure of air blown into the instrument, the CPU  3  that sets the volume of musical notes generated by the sound source  6  according to the detected input pressure, and the drain unit  20 B that adjusts the flow rate of exhausted air such that the relationship between the input pressure and the output of the breath pressure detector  2  follows a concave down curve as the input pressure increases until the output of the breath pressure detector  2  reaches the maximum value. In this curve, the relationship between the input pressure and the output of the breath pressure detector  2  is linear while the air flow path is in the fully closed state. Therefore, even performers who can only produce relatively low input pressures can easily play musical notes at a sufficiently loud volume. This configuration also makes it possible to reduce the amount of work that the performer needs to do because no manual adjustments of a mechanical or electronic valve are required. 
         [0077]    Furthermore, the drain unit  20 B includes the case  22  that forms a flow path for the air, the movable valve  29  that is arranged inside the case  22  and adjusts the flow path according to the distance between the movable valve  29  and the case  22 , the fixed guide  27  that supports the movable valve  29 , and the spring  28  that pushes the movable valve  29  into contact with the case  22  when no air is blown into the instrument and resists movement of the movable valve  29  away from the case  22  according to the magnitude of the input pressure blown into the instrument. This makes it possible to use a simple structure to implement the adjustment unit for adjusting the flow rate of the exhaust air. 
         [0078]    The embodiments described above are only examples of a suitable application of the present invention to an electronic wind instrument, and the present invention is not limited to these examples. 
         [0079]    For example, in the embodiments described above, a single flow path through which air is exhausted is adjusted using a valve (and opening and closing the valve, for example) to adjust the flow rate of the air. However, the present invention is not limited to this example. A plurality of flow paths through which air is exhausted may be provided, and the overall air flow rate though the flow paths can be adjusted by opening and closing valves arranged in each flow path. 
         [0080]    In the embodiments described above, the volume of musical notes generated by the sound source  6  is controlled according to the pressure of air blown into the instrument. However, the present invention is not limited to this example. In addition to controlling the volume, the pitch may be increased or the tone of the musical notes may be brightened as the input pressure increases, or alternatively, all three of the volume, pitch, and brightness of the tone of the musical notes may be increased as the input pressure increases. 
         [0081]    Furthermore, the sound source  6  may be controlled to increase the pitch or brighten the tone of the musical notes without changing the volume as the input pressure increases, or alternatively, both the pitch and brightness of the tone of the musical notes may be increased without changing the volume as the input pressure increases. 
         [0082]    Moreover, the lower-level aspects of the configuration and functions of the components of the electronic wind instrument  100  according to the embodiments described above may be modified as appropriate without departing from the spirit of the present invention. 
         [0083]    Embodiments of the present invention were described above. However, the present invention is not limited to these embodiments, and any configurations included in the scope of the claims and their equivalents are also encompassed by the present invention. 
         [0084]    Next, the present invention will be defined according to the claims first appended when the present application was filed. The claim numbers in the appended claims are the same claims numbers used in the claims first appended when the present application was filed. 
         [0085]    It will be apparent to those skilled in the art that various modification and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents. In particular, it is explicitly contemplated that any part or whole of any two or more of the embodiments and their modifications described above can be combined and regarded within the scope of the present invention.