stringed instrument

Abstract

A stringed instrument comprises: a neck; a plurality of conductive frets arranged at intervals along the neck; a plurality of conductive strings capable of contacting any one of the plurality of frets; a plurality of drive coils, each corresponding to one of the plurality of frets; a signal supply unit supplying a drive signal to each of the plurality of drive coils; a return path connected to each of the plurality of frets; and a voltage detection unit detecting a first detection voltage between a first string of the plurality of strings and the return path during the period when each of the plurality of drive coils is supplied with the drive signal.

Description

Technical Field

[0001] This disclosure relates to a stringed instrument. Background Technology

[0002] Techniques for detecting the position of a player pressing the strings of a stringed instrument have been proposed previously. For example, Patent Document 1 discloses a technique that uses coils installed on the surface of the neck (net) of an electric stringed instrument, at each fret, to detect the position of the pressed string. In the structure of Patent Document 1, voltage pulses are sequentially supplied to each of the multiple strings, and the position of the pressed string is determined by detecting the induced voltage generated in each coil due to the application of the voltage pulses.

[0003] Prior technology documents

[0004] Patent documents

[0005] Patent Document 1: Utility Model Application Publication No. 4-85394 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the structure of Patent Document 1, a large current is generated in each string by supplying a voltage pulse. Therefore, the current in each string may affect the action (pickup) of magnetically detecting vibrations in the strings caused by playing. In view of the above, one aspect of this disclosure aims to detect the fingering position while suppressing the influence on the detection of string vibrations in a stringed instrument.

[0008] A stringed instrument according to one aspect of the present disclosure comprises: a neck; a plurality of conductive frets arranged at intervals along the neck; a plurality of conductive strings capable of contacting any one of the plurality of frets; a plurality of drive coils, each corresponding to one of the plurality of frets; a signal supply unit supplying a drive signal to each of the plurality of drive coils; a return path connected to each of the plurality of frets; and a voltage detection unit detecting a first detection voltage between a first string of the plurality of strings and the return path during the period when each of the plurality of drive coils is supplied with the drive signal. Attached Figure Description

[0009] Figure 1 This is a top view of the electric bass in the first embodiment.

[0010] Figure 2 This is an explanatory diagram illustrating the principle of detecting the position of the pressed string.

[0011] Figure 3 This is an explanatory diagram illustrating the principle of detecting the position of the pressed string.

[0012] Figure 4This is an explanatory diagram illustrating the principle of detecting the position of the pressed string.

[0013] Figure 5 It is a top view of a portion of the fingerboard, magnified.

[0014] Figure 6 This is a top view of the instrument's neck.

[0015] Figure 7 yes Figure 5 A cross-sectional view of line VII-VII in the diagram.

[0016] Figure 8 yes Figure 5 A cross-sectional view of line VIII-VIII in the diagram.

[0017] Figure 9 This is an explanatory diagram illustrating the relationship between each chord and the return path in the first embodiment.

[0018] Figure 10 This is an explanatory diagram illustrating the relationship between each chord and the return path in the second embodiment.

[0019] Figure 11 This is a block diagram illustrating the structure of the detection device.

[0020] Figure 12 This is an explanatory diagram of the operation of the signal supply unit.

[0021] Figure 13 It is a circuit diagram used to supply drive signals to each drive coil.

[0022] Figure 14 This is a circuit diagram illustrating the structure of a voltage detection unit.

[0023] Figure 15 This is an explanatory diagram about the decrease in detection voltage caused by pressing multiple strings.

[0024] Figure 16 This is an explanatory diagram of the reference voltage.

[0025] Figure 17 This is an illustration of the differential voltage between the detected voltage and the reference voltage.

[0026] Figure 18 It concerns the transient response of the amplifier.

[0027] Figure 19 This is an explanatory diagram illustrating the principle of detecting the position of the pressed string in the third embodiment.

[0028] Figure 20 This is an explanatory diagram illustrating the principle of detecting the position of the pressed string in the third embodiment.

[0029] Figure 21This is an explanatory diagram illustrating the principle of detecting the position of the pressed string in the third embodiment.

[0030] Figure 22 This is a block diagram illustrating the structure of the detection device in the third embodiment.

[0031] Figure 23 This is a block diagram illustrating the structure of the signal output section and the string analysis section.

[0032] Figure 24 This is a schematic diagram of the detection data.

[0033] Figure 25 It is a schematic diagram of the time-varying voltage of each string.

[0034] Figure 26 It is part of the flowchart for string analysis processing.

[0035] Figure 27 This is another part of the flowchart for string analysis.

[0036] Figure 28 This is a block diagram illustrating the structure of the signal output section and the string analysis section in the fourth embodiment.

[0037] Figure 29 This is a cross-sectional view showing the relationship between the connecting part and the wire in the fifth embodiment.

[0038] Figure 30 This is a cross-sectional view of the neck in a variation of the fifth embodiment.

[0039] Figure 31 This is a cross-sectional view of the neck in a variation of the fifth embodiment.

[0040] Figure 32 This is a block diagram illustrating the structure of the signal supply unit in a modified example.

[0041] Figure 33 This is a cross-sectional view of the neck in a variation of the first embodiment. Detailed Implementation

[0042] A: First Implementation Method

[0043] Figure 1 This is a top view of the electric bass 100 according to the first embodiment. The electric bass 100 is a stringed instrument comprising: a body 10, a neck 11, a fingerboard 12, a headstock 13, multiple (N) frets 14_1 to 14_N, five strings 15_1 to 15_5, and a detection device 30. The body 10 is the structure that supports the various elements of the electric bass 100. Furthermore, in the following description, the X-axis and Y-axis are assumed to be orthogonal to each other.

[0044] Each of the five strings 15_1 to 15_5 is a linear conductor comprising a first end E1 and a second end E2. The material of each string 15_m (m = 1 to 5) is arbitrary. The neck 11 is a long strip extending along the Y-axis. That is, the Y-axis is the axis extending along the direction of the neck 11. The base end of the neck 11 in the negative direction of the Y-axis is fixed to the body 10. A headstock 13 is provided at the front end of the neck 11 in the positive direction of the Y-axis. Five tuning pegs 16 corresponding to different strings 15_m are provided on the headstock 13. The first end E1 of each string 15_m is fixed to the tuning peg 16. A bridge 17 is provided on the body 10, where the second end E2 of each string 15_m is fixed.

[0045] The fingerboard 12 is a long, plate-like component mounted on the neck 11. The fingerboard 12 is located between the five strings 15_1 to 15_5 and the neck 11. Each string 15_m is spaced apart from the surface of the fingerboard 12. N frets 14_1 to 14_N are conductive components mounted on the surface of the fingerboard 12. Specifically, the N frets 14_1 to 14_N are arranged spaced apart along the Y-axis. Each fret 14_n (n = 1 to N) is a long, strip-like component spanning approximately the entire width of the fingerboard 12 and extending along the X-axis, protruding from the surface of the fingerboard 12. Of the N frets 14_1 to 14_N, fret 14_1 at one end of the arrangement is closest to the headstock 13, and fret 14_N at the other end of the arrangement is closest to the bridge 17.

[0046] A nut 18 is provided at the end of the fingerboard 12 near the headstock 13. Five strings 15_1 to 15_5 are tensioned between the nut 18 and the bridge 17 at a predetermined tension. Specifically, the five strings 15_1 to 15_5 extend at intervals along the Y-axis along the X-axis. Furthermore, any one of the five strings 15_1 to 15_5, 15_m1 (m1 = 1 to 5), is an example of a "first string," and a different string 15_m2 (m2 = 1 to 5, m1 ≠ m2) is an example of a "second string." The nut 18 is made of an insulating material, but it can also be made of a conductive material, as long as it is a structure that does not, for example, contact the return line 22 described later.

[0047] In the open state without the strings being pressed, each of the five strings 15_1 to 15_5 is positioned away from the N frets 14_1 to 14_N. Each string 15_m can be pressed by the player to make contact with any of the N frets 14_1 to 14_N. Pressing the strings is a playing operation that involves pressing each string 15_m toward the fingerboard 12. The player can press the strings at any desired position on the string 15_m within the range of the fingerboard 12.

[0048] Multiple pickups 19 are mounted on the body 10 of the instrument. Each pickup 19 detects the vibrations in the string 15_m caused by the player's playing (specifically, plucking the string) and generates an acoustic signal corresponding to the vibration. The acoustic signals generated by each pickup 19 are then processed, for example, by an audio device (not shown) such as an amplifier, and reproduced as sound waves.

[0049] The detection device 30 detects the presence and position (hereinafter referred to as "string pressing position") of the player pressing the string on each of the five strings 15_1 to 15_5. Specifically, for example, one or more frets 14_n out of the N frets 14_1 to 14_N that come into contact with the string 15_m due to the player pressing the string are detected as the string pressing position for each string 15_m. Furthermore, in Figure 1 The example shown is that the detection device 30 is built into the body 10 of the instrument, but the detection device 30 can also be configured to be separate from the electric bass 100 and connected to the electric bass 100.

[0050] Figure 2 This is an explanatory diagram illustrating the detection principle for the fingering position of any string 15_m. The electric bass 100 has N drive coils 21_1 to 21_N corresponding to different frets 14_n. Each drive coil 21_n is located between adjacent frets 14_n and frets 14_n-1. As described above, N drive coils 21_1 to 21_N are respectively arranged in each interval of the N frets 14_1 to 14_N.

[0051] Figure 2 The return line 22 is a linear wiring consisting of a first end Ea1 and a second end Ea2, extending along the Y-axis at intervals from each string 15_m. The first end Ea1 is the end of the return line 22 located in the positive direction of the Y-axis, and the second end Ea2 is the end of the return line 22 located in the negative direction of the Y-axis. The return line 22 is electrically connected to the string 15_m. Specifically, the return line 22 is connected to the portion of the string 15_m located further along the positive direction of the Y-axis than the N frets 14_1 to 14_N (i.e., the front end side of the neck 11). For example, the first end E1 of the string 15_m is connected to the return line 22. Therefore, the string 15_m and the return line 22 form a coil (hereinafter referred to as "detection coil 28_m"). Furthermore, each of the N frets 14_1 to 14_N is electrically connected to the return line 22.

[0052] For each of the N drive coils 21_1 to 21_N, a drive signal D is supplied sequentially in a time-division manner. The drive signal D is a periodic signal with a periodically varying signal level. When current flows through the drive coil 21_n (primary coil) due to the supply of the drive signal D, an electromotive force is generated in the detection coil 28_m (secondary coil) composed of the string 15_m and the return line 22 due to the mutual inductance caused by the magnetic field generated in the drive coil 21_n. In the first embodiment, the detection voltage V_m between the string 15_m and the return line 22 is detected, and the fingering position is determined based on the detection voltage V_m. The detection voltage V_m is the voltage between the second end E2 of the string 15_m, which is located in the negative Y-axis direction (i.e., the base end side of the neck 11) further than the N frets 14_1 to 14_N, and the second end Ea2 of the return line 22, which is located in the negative Y-axis direction.

[0053] Figure 3 as well as Figure 4 The diagram shows adjacent wires 14_n and 14_n-1 separated by drive coil 21_n. Assume that drive signal D is supplied to drive coil 21_n.

[0054] like Figure 3 As shown, when the section between frets 14_n-1 and 14_n-2 in the string 15_m is pressed, fret 14_n-1, located in the positive Y-axis direction further than the drive coil 21_n which is the object being driven, comes into contact with the string 15_m. Therefore, when the drive signal D is supplied to the drive coil 21_n, an electromotive force is generated in the detection coil 28_m, which is composed of the string 15_m, fret 14_n-1, and return line 22. Therefore, the detection voltage V_m varies periodically in the same way as the drive signal D. Even when the string 15_m is open, the detection voltage V_m also varies periodically.

[0055] On the other hand, such as Figure 4 As shown, when the portion of string 15_m between frets 14_n and 14_n-1 is pressed, fret 14_n, located in the negative Y-axis direction more towards the drive coil 21_n (which is the object being driven), contacts string 15_m. Therefore, even if the drive signal D is supplied to the drive coil 21_n, the voltage of the detection coil 28_m (detection voltage V_m) remains substantially unchanged.

[0056] As described above, the detection voltage V_m during the period when the drive signal D is supplied to each drive coil 21_n (the supply period T_n described later) varies according to the pressing position of the string 15_m. Therefore, the pressing position of the string 15_m can be determined using the detection voltage V_m when the drive signal D is sequentially supplied to each of the N drive coils 21_1 to 21_N. Furthermore, when the string 15_m is in the open state (the state where the string 15_m is not pressed at any position), the detection voltage V_m varies periodically.

[0057] As explained above, in the first embodiment, an electromotive force is generated in the detection coil 28_m, which includes the string 15_m and the return line 22, by the mutual inductance caused by supplying a drive signal D to the drive coil 21_n. Then, the fingering position of each string 15_m is determined by detecting the detection voltage V_m between each string 15_m and the return line 22. Therefore, compared with the method of generating an electromotive force in the drive coil 21_n by supplying a drive signal D to the string 15_m, the current flowing in the string 15_m is reduced. According to the above structure, it is possible to detect the presence and position of each string 15_m with high speed and high accuracy while suppressing the impact on the pickup 19's detection of vibrations generated in the string 15_m due to playing.

[0058] Furthermore, in the first embodiment, as described above, the first end E1 of each string 15_m is connected to the first end Ea1 of the return line 22, and the voltage between the second end E2 of each string 15_m and the second end Ea2 of the return line 22 is detected as the detection voltage V_m. Therefore, the contact of each string 15_m with any one of the N frets 14_1 to 14_N can be detected throughout the entire area of ​​the neck 11 in the Y-axis direction.

[0059] Figure 5 This is a top view of an enlarged portion of the fingerboard 12. Figure 6 It has been removed Figure 5 A top view of the five strings 15_1~15_5 and the neck 11 behind the fingerboard 12. (See attached image.) Figure 5 as well as Figure 6 As illustrated, when viewed from a direction perpendicular to the surface of the finger plate 12 (hereinafter referred to as "top view"), drive coils 21_n are provided between each of the frets 14_n and frets 14_n-1.

[0060] Figure 7 yes Figure 5 Cross-sectional view of line VII-VII in the diagram. Figure 8 yes Figure 5 A cross-sectional view of line VIII-VIII in the diagram. (See also...) Figures 6 to 8As illustrated, a groove 112 is formed on the surface of the neck 11 opposite to the fingerboard 12, and a groove 123 is formed on the surface of the fingerboard 12 opposite to the neck 11.

[0061] Grooves 112 and 123 are elongated recesses extending along the Y-axis. A space (hereinafter referred to as "reservoir space Q") enclosed by the inner surfaces of grooves 112 and 123 is formed between the neck 11 and the fingerboard 12. The reservoir space Q is an elongated space extending along the Y-axis over the entire area of ​​the neck 11 in the Y-axis direction. Alternatively, the reservoir space Q may be formed by only one of grooves 112 and 123. That is, one of grooves 112 and 123 may be omitted.

[0062] The wiring substrate 20 is housed in the storage space Q. That is, the wiring substrate 20 is disposed between the neck 11 and the fingerboard 12. The wiring substrate 20 is a strip-shaped plate-like component that extends along the Y-axis over the entire area of ​​the neck 11 in the Y-axis direction. The wiring substrate 20 is a mounting component in which multiple wirings are formed on the surface and inside of an insulating substrate. For example, a multilayer substrate with multiple insulating layers and multiple conductive layers alternately stacked is used as the wiring substrate 20.

[0063] On the surface of the wiring substrate 20 opposite to the finger plate 12 (hereinafter referred to as "mounting surface 20a"), N drive coils 21_1 to 21_N, N connection portions 24_1 to 24_N, return lines 22, and reference lines 23 are provided. The return lines 22 and reference lines 23 are wirings that extend along the Y-axis direction throughout the entire area of ​​the wiring substrate 20 in the Y-axis direction, and are formed, for example, as conductive patterns on the mounting surface 20a.

[0064] As described above, the return path 22 is a linear wiring extending along the Y-axis between the first end Ea1 and the second end Ea2. The return path 22 is positioned near the center in the X-axis direction of the mounting surface 20a of the wiring substrate 20. That is, the return path 22 extends along the centerline of the wiring substrate 20. Figure 7 as well as Figure 8 As understood, the fingerboard 12 is located between each string 15_m and the return path 22.

[0065] Reference line 23 is a virtual string that does not directly contribute to the playing of the electric bass 100. Like return line 22, reference line 23 is a straight line extending along the Y-axis. Reference line 23 and return line 22 are spaced apart on the mounting surface 20a. Specifically, reference line 23 is formed along the edge of the wiring substrate 20 in the positive X-axis direction.

[0066] N driving coils 21_1 to 21_N are arranged at intervals along the Y-axis. For example... Figure 6 as well as Figure 7 As illustrated, each drive coil 21_n is, for example, a chip coil mounted on the mounting surface 20a. Each drive coil 21_n is positioned at the center of the wiring substrate 20 in the X-axis direction. Therefore, each drive coil 21_n overlaps with the return line 22 when viewed from above. Specifically, each drive coil 21_n is attached to the mounting surface 20a in a manner that crosses the return line 22. That is, N drive coils 21_1 to 21_N are located between the finger plate 12 and the return line 22. According to the above structure, the N drive coils 21_1 to 21_N are not exposed to the outside of the electric bass 100. Therefore, each drive coil 21_n can be provided while maintaining the appearance of the finger plate 12.

[0067] like Figure 6 As illustrated, N connectors 24_1 to 24_N are arranged at intervals along the Y-axis. Specifically, each connector 24_n is located at the center of the wiring board 20 along the X-axis. Therefore, each connector 24_n overlaps with the return line 22 when viewed from above. Each connector 24_n is a connection terminal or metal piece electrically connected to the return line 22.

[0068] Each of the N connecting portions 24_1 to 24_N corresponds to a different wire 14_n. In a top view, each connecting portion 24_n overlaps with the wire 14_n corresponding to that connecting portion 24_n. Therefore, each connecting portion 24_n is located between adjacent drive coils 21_n and drive coils 21_n-1.

[0069] like Figure 8 As illustrated, each fret 14_n has a protrusion 141. The protrusion 141 protrudes from a portion of the fret 14_n extending along the X-axis toward the neck 11. On the other hand, mounting holes 122 corresponding to each fret 14_n are formed on the fingerboard 12. Each mounting hole 122 is a through hole penetrating the fingerboard 12. The protrusion 141 of each fret 14_n penetrates the fingerboard 12 by being inserted into the mounting hole 122. The front end of the protrusion 141 of each fret 14_n is connected to the connecting portion 24_n within the receiving space Q. That is, each connecting portion 24_n is connected to the protrusion 141 of the fret 14_n corresponding to that connecting portion 24_n. Alternatively, multiple protrusions 141 may be formed on a single fret 14_n.

[0070] As described above, each of the N filaments 14_n is electrically connected to the return line 22 via a corresponding connector 24_n. Based on this structure, each filament 14_n can be electrically connected to the return line 22 using a simple structure that eliminates the need for wiring. On the other hand, the reference line 23 does not contact any of the N filaments 14_1 to 14_N.

[0071] Figure 9 This is an explanatory diagram illustrating the relationship between the five strings 15_1 to 15_5, the return line 22, and each drive coil 21_n. The five strings 15_1 to 15_5 are connected to a return line 22. Specifically, as described above, the end of each string 15_m located in the positive direction of the Y-axis (first end E1) is connected to the end of the return line 22 located in the positive direction of the Y-axis (first end Ea1).

[0072] As described above, in the first embodiment, the mutual inductance between each drive coil 21_n and the detection coil 28_m, which includes the string 15_m and the return line 22, is utilized. That is, the magnetic flux generated in each drive coil 21_n by supplying the drive signal D is linked with the detection coil 28_m, which includes the string 15_m and the return line 22.

[0073] As described above, the magnetic flux generated in a drive coil 21_n is linked to the detection coil 28_m, which includes each of the five strings 15_1 to 15_5. That is, the drive coil 21_n is shared for detecting the finger position of each of the five strings 15_1 to 15_5. Therefore, compared to providing a separate drive coil 21_n for each string 15_m, the structure of the electric bass 100 can be simplified by reducing the number of drive coils 21_n. Furthermore, the detection coil 28_m1 is an example of a "first detection coil," and the detection coil 28_m2 is an example of a "second detection coil."

[0074] Figure 10 This is a schematic diagram of a method in which a separate return path 22 is provided for each of the five strings 15_1 to 15_5 (hereinafter referred to as the "second embodiment"). A detection coil 28_m is formed by connecting each string 15_m to its own independent return path 22. That is, in the second embodiment, five detection coils 28_m corresponding to different strings 15_m are arranged side-by-side at intervals in the X-axis direction. In the first embodiment, since the five strings 15_1 to 15_5 are connected to the return path 22, the structure of the electric bass 100 can be simplified by reducing the number of return paths 22 compared to the second embodiment.

[0075] In the second embodiment, in order to link the magnetic flux of each drive coil 21_n with the five detection coils 28_m, each drive coil 21_n needs to be formed to be longer in the X-axis direction. Specifically, for example, a drive coil 21_n with a dimension spanning the full width of the finger plate 12 is required.

[0076] In contrast to the second embodiment, in the first embodiment, five strings 15_1 to 15_5 are connected to a single return line 22. In the above structure, as... Figure 9It is understood that the five detection coils 28_m corresponding to different strings 15_m are in a state of close proximity to each other near the return path 22. Therefore, even with a small size of the drive coil 21_n in the X-axis direction, it is possible to link the magnetic flux of the drive coil 21_n with the five detection coils 28_m. That is, it is possible to reduce the size of the drive coil 21_n required to achieve magnetic coupling between the detection coil 28_m corresponding to each string 15_m and each drive coil 21_n.

[0077] Furthermore, in the above description, the second embodiment has been illustrated for ease of comparison with the first embodiment, but the second embodiment is not excluded from the scope of this disclosure. The structure of the second embodiment is, of course, also included within the scope of this disclosure. That is, in this disclosure, a separate return line 22 can be provided for each of the five strings 15_1 to 15_5, and a detection coil 28_m can be individually constructed for each string 15_m through the connection between each string 15_m and each return line 22. Furthermore, in the second embodiment, except that the return line 22 is provided for each string 15_m, it is the same as the first embodiment.

[0078] Figure 11 This is a block diagram illustrating the structure of the detection device 30. The detection device 30 includes a signal supply unit 40, a voltage detection unit 50, and a string analysis unit 60A. The signal supply unit 40 supplies a drive signal D to each of the N drive coils 21_1 to 21_N.

[0079] Figure 12 This is an explanatory diagram illustrating the operation of supplying drive signals D to each drive coil 21_n. (For example...) Figure 12 As illustrated, the operation of supplying drive signal D to each of the N drive coils 21_1 to 21_N is repeated, with each of the N supply periods T_1 to T_N on the time axis constituting a cycle. Each supply period T_n is a period of a predetermined length. Within one supply period T_n, a drive signal D is supplied to one drive coil 21_n. That is, for each of the N drive coils 21_1 to 21_N, a drive signal D is supplied in a time-division manner according to each supply period T_n.

[0080] Figure 13 This is a circuit diagram showing the structure for supplying a drive signal D to one of the N drive coils 21_n (21_1~21_N). The configuration for each of the N drive coils 21_1~21_N is as follows. Figure 13 The structure.

[0081] The signal supply unit 40 includes N drive circuits 41_1 to 41_N corresponding to different drive coils 21_n. Each drive circuit 41_n outputs a drive signal D0 with periodic voltage variations. The drive circuit 41_n is, for example, an inverter circuit composed of logic circuits.

[0082] The drive signal D0 is a rectangular wave of voltage variation at frequency F0. Frequency F0 is a frequency within a specified range, such as 2MHz (e.g., above 1.5MHz and below 2.5MHz). For example, frequency F0 is set to a value of approximately 2.3MHz. The voltage amplitude of the drive signal D0 is, for example, 5Vp-p (peak-to-peak).

[0083] The output terminal of the drive circuit 41_n is connected to one end of the drive coil 21_n via signal line 42. Furthermore, the other end of each drive coil 21_n is connected to a common line 47. Signal line 42 and common line 47 are wirings formed on the wiring substrate 20. Common line 47 is grounded.

[0084] A capacitor 43, a low-pass filter 44, a resistor 45, and a capacitor 46 are disposed on signal line 42. Capacitor 43 removes the DC component of the drive signal D. The low-pass filter 44 suppresses the high-frequency components of the drive signal D. The drive coil 21_n, resistor 45, and capacitor 46 constitute a resonant circuit. The resistance value of resistor 45 and the capacitance value of capacitor 46 are set to make the resonant frequency of the resonant circuit coincide with or approximate the frequency F0 of the drive signal D0, and to make the Q value of the resonant characteristic an appropriate value.

[0085] In the above structure, the drive signal D, after removing high-frequency components from the drive signal D0 output from the drive circuit 41_n, is supplied to the drive coil 21_n. The drive signal D is a sinusoidal periodic signal with voltage fluctuations at the same frequency F0 as the drive signal D0. The voltage amplitude of the drive signal D is, for example, approximately 3.8Vp-p.

[0086] Figure 11 The voltage detection unit 50 detects the detection voltage V_m for each of the five strings 15_1 to 15_5 during each supply period T_n. As described above, the detection voltage V_m varies periodically in the same way as the drive signal D. When the voltage amplitude of the initial drive signal D0 is set to 5Vp-p, the voltage amplitude of the detection voltage V_m is, for example, about 10mVp-p. The voltage detection unit 50 amplifies the detection voltage V_m to a detectable voltage.

[0087] Figure 14 This is a circuit diagram illustrating the structure of the voltage detection unit 50. Figure 14 The diagram shows the first end E1 and the second end E2 of each string 15_m. The first end E1 is the end of the string 15_m that is fixed to the headstock 13, and the second end E2 is the end of the string 15_m that is fixed to the body 10 (bridge 17).

[0088] Figure 14The diagram illustrates the first end Ea1 and the second end Ea2 of the return path 22, and the first end Eb1 and the second end Eb2 of the reference line 23. The first end Eb1 is the end of the reference line 23 located in the positive Y-axis direction, and the second end Eb2 is the end of the reference line 23 located in the negative Y-axis direction. As described above, the first end E1 of each of the five strings 15_1 to 15_5 is connected to the first end Ea1 of the return path 22. Similarly, the first end Eb1 of the reference line 23 is also connected to the first end Ea1 of the return path 22.

[0089] A resistor element 51_m is connected in series between the first end E1 of each string 15_m and the return line 22. Specifically, one end of the resistor element 51_m is connected to the first end E1 of the string 15_m, and the other end of the resistor element 51_m is connected to the first end Ea1 of the return line 22. The resistor element 51_m is used to ensure the impedance of the detection coil 28_m when the first fret 14_1 is pressed. The resistance value of the resistor element 51_m exceeds the resistance value of the string 15_m. Furthermore, resistor element 51_m1 is an example of a "first resistor element", and resistor element 51_m2 is an example of a "second resistor element".

[0090] Furthermore, the resistivity of each string 15_m varies due to individual differences. According to the first embodiment, since the resistive element 51_m is connected to each string 15_m, the impedance difference between the five strings 15_1 to 15_5 is reduced. That is, the impedance of the five strings 15_1 to 15_5 can be made equal. Furthermore, the resistive element 51_m is not provided with respect to the reference line 23.

[0091] The voltage detection unit 50 includes five detection units 52_1 to 52_5, an output circuit 53, and a reference unit 54. The five detection units 52_1 to 52_5 correspond to different strings 15_m. The second terminal E2 of each string 15_m is connected to the detection unit 52_m. Each detection unit 52_m is a circuit that detects the detection voltage V_m of the string 15_m. The five detection units 52_1 to 52_5 detect the detection voltages V_1 to V_5 of five systems corresponding to different strings 15_m in parallel. Alternatively, a single detection unit 52_m can detect the detection voltage V_m associated with each of the five strings 15_1 to 15_5 in a time-division multiplexing manner.

[0092] Each detection unit 52_m includes a bandpass filter 521, an amplifier 522, and a comparator 523. The bandpass filter 521 consists of two resistive elements and two capacitors, selectively passing the frequency band component of the voltage at the second terminal E2 of the string 15_m that includes the frequency F0 of the drive signal D. The voltage Va_m processed by the bandpass filter 521 is supplied to the positive input terminal (+) of the amplifier 522.

[0093] The output circuit 53 includes a bandpass filter 531 and a resistor 532. The bandpass filter 531 selectively passes the voltage component of the second terminal Ea2 of the return line 22, which includes the frequency F0 of the drive signal D. The voltage V0 processed by the bandpass filter 531 is supplied to the negative input terminal (-) of the amplifier 522 in each detection unit 52_m. The negative input terminal of the amplifier 522 in each of the five detection units 52_1 to 52_5 is grounded via the resistor 532. The difference between voltage Va_m and voltage V0 (differential input voltage) corresponds to the detection voltage V_m.

[0094] Each detection unit 52_m has an amplifier 522 that detects and amplifies the detection voltage V_m of the string 15_m. Specifically, the amplifier 522 amplifies the detection voltage V_m with a gain of, for example, about 45dB. The amplifier 522 generates a detection voltage U_m by detecting the amplified detection voltage V_m. Specifically, the amplifier 522 outputs a detection voltage U_m with a voltage value corresponding to the voltage amplitude of the detection voltage V_m.

[0095] As described above, since the amplitude of the detection voltage V_m varies depending on the pressing position of string 15_m, the voltage value of the detection voltage U_m also varies depending on the pressing position of string 15_m. Therefore, the pressing position of string 15_m can be determined using the detection voltage U_m. For example, the pressing position can be determined by checking whether the detection voltage U_m exceeds a predetermined threshold for each supply period T_n.

[0096] Furthermore, considering any two detection units 52_m1 and 52_m2, the amplifier 522 of detection unit 52_m1 is an example of a "first detection circuit," and the amplifier 522 of detection unit 52_m2 is an example of a "second detection circuit." Additionally, the detection voltages V_m1 and U_m1 are examples of a "first detection voltage," and the detection voltages V_m2 and U_m2 are examples of a "second detection voltage."

[0097] Furthermore, in addition to playing with only one string 15_m out of the five strings 15_1 to 15_5 pressed, it is also envisioned that multiple strings 15_m be pressed in parallel. In the state where multiple strings 15_m are pressed in parallel, they are electrically connected via frets 14_n. Therefore, in the state where multiple strings 15_m are pressed in parallel, the detection voltage U_m corresponding to each string 15_m is lower compared to the state where only one string 15_m is pressed.

[0098] Figure 15This is an explanatory diagram illustrating the decrease in the detection voltage U_1 caused by pressing multiple 15_m strings. Figure 15 In the figure, the detection voltage U_1 of string 15_1 is shown on the vertical axis. Figure 15 The voltage U_1-off is the detection voltage U_1 when the string 15_1 is not pressed (open state), and the voltage U_1-on is the detection voltage U_1 when the string 15_1 is pressed. Figure 15 The fretting in the fingerboard involves the player pressing the string, resulting in two frets, the 1st and 5th frets 14_15 and the 1st and 6th frets 14_16, contacting the string 15_m. Furthermore, in the area of ​​the fingerboard 12 near the second end E2 of each string 15_m, the spacing between the frets 14_n is narrower. Therefore, even when the player presses only one part of the string 15_m, two frets 14_n are simultaneously in contact with the string 15_m. Considering the above, in Figure 15 In the diagram, the state is set so that the two frets 14_n (14_15, 14_16) are in contact with the string 15_m.

[0099] Figure 15 In the diagram, for each of several states with different numbers of strings 15_m pressed simultaneously by the performer (hereinafter referred to as "simultaneous string pressing number"), the detection voltages U_1-off and U_1-on are illustrated. State 1 is the state where the four strings 15_2 to 15_5 (excluding string 15_1) are open. State 2 is the state where string 15_2 is pressed and strings 15_3 to 15_5 are open. State 3 is the state where strings 15_2 and 15_3 are pressed and strings 15_4 and 15_5 are open. State 4 is the state where strings 15_2 to 15_4 are pressed and string 15_5 is open. State 5 is the state where the four strings 15_2 to 15_5 (excluding string 15_1) are pressed. Figure 15 It is understood that there is a tendency for the detection voltage U_1-off and the detection voltage U_1-on to decrease as the number of simultaneous string presses increases.

[0100] As described above, in order to accurately determine the pressing position of each string 15_m even when the detection voltage U_m depends on the number of strings pressed simultaneously, in the first embodiment, the voltage of the reference line 23 (hereinafter referred to as "reference voltage R") is used.

[0101] As described above, since reference line 23 is connected to return line 22, a coil (hereinafter referred to as "reference coil") is formed by reference line 23 and return line 22, similar to each string 15_m. The magnetic flux generated in each drive coil 21_n by supplying the drive signal D links with the reference coil, which includes reference line 23 and return line 22. Therefore, when current flows through drive coil 21_n (primary coil) by supplying the drive signal D, an electromotive force is also generated in the reference coil (secondary coil) in addition to each detection coil 28_m due to the mutual inductance caused by the magnetic field generated in drive coil 21_n. The reference voltage R is the voltage between return line 22 and reference line 23.

[0102] Figure 14 Reference unit 54 is a circuit used to detect the reference voltage R. Reference unit 54 includes a bandpass filter 541 and an amplifier 542. Like bandpass filter 521, bandpass filter 541 selectively passes the frequency band component of the voltage at the second terminal Eb2 of reference line 23, including the frequency F0 of the drive signal D. The voltage Vr processed by bandpass filter 541 is supplied to the positive input terminal (+) of amplifier 542. The voltage V0 processed by bandpass filter 541 is supplied to the negative input terminal (-) of amplifier 542.

[0103] Amplifier 542 is an amplifier that detects and amplifies the voltage Vr of reference line 23. The structure of amplifier 542 is the same as that of amplifier 522. Therefore, amplifier 542 amplifies the differential voltage between the voltage Vr of reference line 23 and the voltage V0 of return line 22, and outputs a reference voltage R after detecting and amplifying the voltage. That is, it outputs a reference voltage R with a voltage value corresponding to the voltage amplitude of the differential voltage between voltages Vr and V0. Amplifier 542 amplifies the differential voltage with a gain of, for example, about 40 dB. That is, the gain of amplifier 542 is lower than that of amplifier 522.

[0104] Each detection unit 52's comparator 523 compares the detected voltage U_m with the reference voltage R and generates an output signal Z_m based on the comparison result. The output signal Z_m is a binary signal that is synchronously set to either a high level or a low level during each supply period T_n, in accordance with the drive signal D supplied to each drive coil 21_n. Specifically, comparator 523 sets the output signal Z_m to a high level when the detected voltage U_m exceeds the reference voltage R, and sets the output signal Z_m to a low level when the detected voltage U_m is lower than the reference voltage R. That is, when the differential voltage (U_m - R) between the detected voltage U_m and the reference voltage R is positive, the output signal Z_m is set to a high level; when the differential voltage (U_m - R) is negative, the output signal Z_m is set to a low level. As described above, the reference voltage R corresponds to the threshold value compared with the detected voltage U_m.

[0105] Figure 16 This is an explanatory diagram of the reference voltage R. Figure 16 This is an example of detecting the voltage U_m. Figure 15 The curve of the reference voltage R (R-off, R-on) is also recorded. Figure 16 The reference voltage R-off is the reference voltage R when string 15_1 is open, and the reference voltage R-on is the reference voltage R when string 15_1 is closed.

[0106] like Figure 16 It is understood that the reference voltage R of reference line 23 varies depending on whether string 15_1 is pressed. Specifically, the reference voltage R-off when string 15_1 is open exceeds the reference voltage R-on when string 15_1 is pressed. Furthermore, as... Figure 16 It is understood that as the number of strings pressed simultaneously increases, the reference voltages R-off and R-on tend to decrease. That is, the detection voltage U_1 and the reference voltage R are interconnected depending on the number of strings pressed simultaneously. Therefore, by analyzing the detection voltage U_m with the reference voltage R as a reference value, it is possible to determine with high accuracy whether a string is pressed (and thus the position of the pressed string) on ​​string 15_m.

[0107] Figure 17 This is a graph showing the differential voltage (U_1-R) between the detection voltage U_1 and the reference voltage R for each of states 1 to 5. As described above, based on the structure of determining the sign of the differential voltage (U_1-R) between the detection voltage U_m and the reference voltage R, the presence or absence of the pressed string of string 15_1 can be determined with high precision. This can be seen from... Figure 17Confirmed. That is, when the differential voltage (U_m-R) between the detected voltage U_m and the reference voltage R is positive, comparator 523 sets the output signal Z_m to a high level, and when the differential voltage (U_m-R) is negative, it sets the output signal Z_m to a low level.

[0108] As described above, the reference voltage R varies along with each detection voltage U_m according to the number of strings pressed simultaneously. Therefore, by comparing each detection voltage U_m with the reference voltage R as described above, even when multiple strings 15_m are pressed simultaneously, the pressing position of each string 15_m can be determined with high accuracy.

[0109] Figure 18 This is an explanatory diagram of the transient response of amplifier 522. Figure 18 The waveform of the driving signal D0, as well as the time variations of the detection voltages V_m and U_m, were recorded. Figure 18 It can be determined that the detected voltage U_m reaches a steady-state voltage after approximately 10 waves of the drive signal D0. When the frequency F0 of the drive signal D0 is set to 2.3MHz, the time required for the detected voltage U_m to rise is approximately 4 microseconds. On the other hand, from the moment the drive signal D to the drive coil 21_n ends, the detected voltage U_m decreases after approximately 26 waves of the drive signal D0 (approximately 11 microseconds).

[0110] As described above, the time required for the detection voltage U_m to decrease is longer than the time required for the detection voltage U_m to increase. That is, the increase in detection voltage U_m is faster than the decrease. Therefore, the time required for the decrease in detection voltage U_m is ensured as the duration of each supply period T_n. When the number N of frets 14_n is set to 24, the time for supplying the drive signal D to all frets 14_n is approximately 0.27 microseconds (=24×26×1 / 2.3MHz). Therefore, the fingering position of each string 15_m can be determined with a sufficiently low delay that is imperceptible to the player.

[0111] The string pressing analysis unit 60A determines the pressing position of each string 15_m based on the output signal Z_m corresponding to each string 15_m. For example, when the output signal Z_m changes from a low level to a high level during the supply period T_n, the string pressing analysis unit 60A determines the fret 14_n-1 as the pressing position of the string 15_m.

[0112] B: Third Implementation Method

[0113] The third embodiment will be described below. Furthermore, in the embodiments illustrated below, elements that function the same as in the first embodiment will be referred to by the same symbols as in the first embodiment, and detailed descriptions will be omitted as appropriate.

[0114] Figure 19 This is an explanatory diagram illustrating the detection principle of the pressing position of any string 15_m in the third embodiment. The electric bass 100 of the third embodiment, like that of the first embodiment, has N drive coils 21_1 to 21_N corresponding to different frets 14_n. A drive signal D is sequentially supplied to each of the N drive coils 21_1 to 21_N in a time-division manner.

[0115] In the first embodiment, the drive coil 21_n is disposed between adjacent wires 14_n and 14_n-1. Figure 2 That is, the drive coil 21_n is located in the positive direction of the Y-axis relative to the wire 14_n. For example... Figure 19 As illustrated, in the third embodiment, the drive coil 21_n is located between adjacent wires 14_n and 14_n+1. That is, the drive coil 21_n is located in the negative direction of the Y-axis relative to the wire 14_n.

[0116] Similar to the first embodiment, the return path 22 is a wiring extending along the Y-axis at intervals from each string 15_m, including a first end Ea1 and a second end Ea2. In the first embodiment, the first end E1 of each string 15_m is connected to the return path 22. In the third embodiment, each string 15_m is not electrically connected to the return path 22. Each of the N frets 14_1 to 14_N is electrically connected to the return path 22 in the same manner as in the first embodiment. Furthermore, in the third embodiment, the aforementioned reference line 23 can be omitted.

[0117] Figure 20 as well as Figure 21 The diagram shows drive coil 21_n-1 and drive coil 21_n, and wire 14_n-1 and wire 14_n. Figure 20 as well as Figure 21 The voltage C0_m,n is the voltage of the chord 15_m during the period when a drive signal D is supplied to any one of the drive coils 21_n.

[0118] exist Figure 20 In the configuration, string 15_m is set to be unpressed. Figure 20 In this state, since the return line 22 is electrically insulated from the string 15_m, the detection coil 28_m is not formed. Therefore, even if current flows through the drive coil 21_n-1 by supplying the drive signal D during the supply period T_n-1, the voltage C0_m,n-1 of the string 15_m remains substantially unchanged. Similarly, if current flows through the drive coil 21_n by supplying the drive signal D during the immediately following supply period T_n, the voltage C0_m,n of the string 15_m also remains substantially unchanged.

[0119] exist Figure 21 In this configuration, the string 15_m is set to contact the fret 14_n due to the player pressing the string. That is, the fret 14_n is the position where the string is pressed. As a result of the contact between the string 15_m and the fret 14_n, a detection coil 28_m with one turn is formed by the string 15_m, the fret 14_n, and the return line 22.

[0120] exist Figure 21 In the current state, even if current flows through the drive coil 21_n-1 by supplying the drive signal D during the supply period T_n-1, the voltage C0_m,n-1 of the string 15_m remains substantially unchanged. On the other hand, when current flows through the drive coil 21_n by supplying the drive signal D during the immediate supply period T_n, an electromotive force is generated in the detection coil 28_m (secondary coil) formed by the structure of the string 15_m, the fret 14_n, and the return line 22 due to the mutual inductance caused by the magnetic field generated in the drive coil 21_n. Therefore, the voltage C0_m,n varies periodically in the same way as the drive signal D.

[0121] As illustrated above, in the state where string 15_m and fret 14_n are not in contact ( Figure 20 Under these conditions, the voltage C0_m,n-1 of string 15_m is essentially the same as the voltage C0_m,n, while the state where string 15_m and fret 14_n are in contact due to pressing the string ( Figure 21 Under these conditions, voltage C0_m,n-1 differs from voltage C0_m,n. That is, voltages C0_m,1 to C0_m,n-1 differ from voltages C0_m,n to C0_m,N. Therefore, the fingering position of each string 15_m can be determined based on whether there are changes in the N voltages C0_m,1 to C0_m,N detected during different supply periods T_n. Specifically, as illustrated above, when voltages C0_m,1 to C0_m,n-1 differ from voltages C0_m,n to C0_m,N, it can be determined that the position of fret 14_n in string 15_m is being pressed.

[0122] Figure 22 This is a block diagram illustrating the structure of the detection device 30 in the third embodiment. The detection device 30 in the third embodiment includes a signal supply unit 40, a signal output unit 55, and a string analysis unit 60B. Similar to the first embodiment, the signal supply unit 40 supplies a drive signal D to each of the N drive coils 21_1 to 21_N. Specifically, for each of the N drive coils 21_1 to 21_N, the drive signal D is supplied in a time-division manner for each supply period T_n.

[0123] Figure 23This is a block diagram illustrating the structure of the signal output unit 55 and the string analysis unit 60B. The signal output unit 55 generates a voltage C_m,n corresponding to the voltage C0_m,n of each string 15_m, and a voltage Cref_n (hereinafter referred to as the "reference voltage") corresponding to the voltage Cref0_n of the return line 22. (Refer to...) Figure 20 as well as Figure 21 The voltage C0_m_n is the voltage of the chord 15_m during the supply period T_n of the drive signal D to the drive coil 21_n. On the other hand, the voltage Cref0_n is the voltage of the return line 22 during the supply period T_n.

[0124] The signal output unit 55 includes five output circuits 56_1 to 56_5 corresponding to different strings 15_m, and an output circuit 57 corresponding to the return line 22. The output circuit 56_m generates a voltage C_m,n corresponding to the voltage C0_m,n of the string 15_m during the supply period T_n. Specifically, the output circuit 56_m includes an amplifier that amplifies the voltage C0_m,n, a rectifier circuit that rectifies the amplified voltage C0_m,n, and a smoothing circuit that smooths the rectified voltage C_m,n. Therefore, the voltage C_m_n is a DC voltage corresponding to the amplitude of the voltage C0_m,n. Similarly, the output circuit 57 generates a reference voltage Cref_n corresponding to the voltage Cref0_n of the return line 22 during the supply period T_n. Specifically, the output circuit 57 includes an amplifier that amplifies the voltage Cref0_n, a rectifier circuit that rectifies the amplified voltage Cref0_n, and a smoothing circuit that smooths the rectified voltage Cref0_n. Therefore, the reference voltage Cref_n is a DC voltage corresponding to the amplitude of the voltage Cref0_n.

[0125] The string-pressing analysis unit 60B determines the presence and position (pressing position) of each string 15_m based on the voltage C_m,n of each string 15_m and the reference voltage Cref_n of the return line 22. Specifically, the string-pressing analysis unit 60B includes a control device 61, a storage device 62, five A / D converters 63_1 to 63_5 corresponding to different strings 15_m, and an A / D converter 64 corresponding to the return line 22.

[0126] A / D converter 63_m converts the voltage C_m,n supplied from output circuit 56_m from analog to digital. A / D converter 64 converts the reference voltage Cref_n supplied from output circuit 57 from analog to digital.

[0127] The control device 61 is one or more processors that perform various arithmetic and control processes. Specifically, the control device 61 is composed of one or more processors such as CPU (Central Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit).

[0128] Storage device 62 is one or more memories that store programs executed by control device 61 and various data used by control device 61. For example, recording media such as semiconductor recording media and magnetic recording media, or a combination of multiple recording media, are used as storage device 62.

[0129] The storage device 62 stores the detection data in units of time. A unit of time is a period in which a drive signal D is supplied to each of the N drive coils 21_1 to 21_N. That is, a unit of time corresponds to N quantities of time corresponding to the period of supplying drive signal D to each drive coil 21_n.

[0130] Figure 24 This is a schematic diagram of the detection data. The detection data is for each of the five strings 15_1 to 15_5, including N voltages C_m,1 to C_m,N corresponding to different supply periods T_n. Each voltage C_m,n is a value converted by A / D converter 63_m. Alternatively, voltage C_m,n can also be expressed as a value corresponding to the drive coil 21_n or the fret 14_n. Furthermore, the detection data includes N reference voltages Cref_1 to Cref_N corresponding to different supply periods T_n. Each reference voltage Cref_n is a value converted by A / D converter 64.

[0131] Figure 25 This is a pattern diagram showing the time variations of N voltages C_m,1 to C_m,N stored in the detection data for any single string 15_m, and N reference voltages Cref_1 to Cref_N stored in the detection data for the return line 22. Figure 25 In this context, the total number N of frets 14_n is set to "24", and the state of one fret 14_18 being pressed is defined. In the following description, the last fret 14_N (N=24) closest to the bridge 17 among the N frets 14_1~14_N is referred to as the "final fret".

[0132] like Figure 25As illustrated, the voltages C_m,1 to C_m,17 from the initial supply period T_1 within a unit period to the previous supply period T_17 corresponding to the string-pressing position T_18 are lower than the voltages C_m,18 to C_m,24 from the supply period T_18 corresponding to the string-pressing position to the supply period T_24 corresponding to the final fret 14_24. Similarly, the reference voltages Cref_1 to Cref_17 from the initial supply period T_1 within a unit period to the supply period T_17 are lower than the reference voltages Cref_18 to Cref_24 from the supply period T_18 corresponding to the string-pressing position to the supply period T_24.

[0133] Figure 25 The diagram illustrates the difference (hereinafter referred to as the "detection voltage") V_m,n between the voltage C_m,n and the reference voltage Cref_n during each supply period T_n (V_m,n = |C_m,n - Cref_n|). Figure 25 It is understood that the detection voltages V_m,1 to V_m,17 from the initial supply period T_1 within a unit period to the previous supply period T_17 corresponding to the string pressing position T_18 are lower than the detection voltages V_m,18 to V_m,24 from the supply period T_18 corresponding to the string pressing position to the supply period T_24 corresponding to the final fret 14_24. From the above explanation, it can be understood that the presence and position (string pressing position) of the pressed string in string 15_m can be determined based on whether the detection voltage V_m,n changes within a unit period and the timing of such changes.

[0134] Figure 26 as well as Figure 27 This is a flowchart of the process (hereinafter referred to as "string analysis process") performed by the control device 61 (string analysis unit 60B) to determine the string pressing position of each string 15_m. The string analysis process is performed according to the update of the detection data in each unit period. That is, the string analysis process is performed in each unit period.

[0135] When the string analysis process begins, the control device 61 selects the maximum value Cmax from five voltages C_1,N to C_5,N corresponding to different strings 15_m (S1). The candidate voltage C_m,N selected as the maximum value Cmax is the voltage corresponding to the final fret 14_N among the N voltages C_m,1 to C_m,N corresponding to the string 15_m. That is, the maximum value Cmax is selected from the five voltages C_1,N to C_5,N during the supply period T_N of the drive signal D supplied to the final stage drive coil 21_N.

[0136] Control device 61 selects any one of the five strings 15_1 to 15_5 (hereinafter referred to as "selected string 15_m") (S2). For example, control device 61 initializes the number m of selected string 15_m to "1". Control device 61 determines whether processing has been performed on all five strings 15_1 to 15_5 (S3). If processing has been performed on all strings 15_m (S3: Yes), control device 61 ends the string analysis processing.

[0137] If there is an unselected string 15_m (S3: No), the control device 61 calculates the differential voltage δ_m for the selected string 15_m (S4). The differential voltage δ_m is a value obtained by subtracting the voltage C_m,N corresponding to the selected string 15_m and the final fret 14_N from the maximum value Cmax (δ_m = Cmax - C_m,N).

[0138] The voltage C_m,n of the selected string 15_m can sometimes be affected by other strings 15_m'. Even when the selected string 15_m is not actually pressed, the voltage C_m_n of the selected string 15_m may increase due to the influence of other strings 15_m',n. That is, in the state where the voltage C_m,n of the selected string 15_m is affected by other strings 15_m' (hereinafter referred to as "crosstalk state"), the differential voltage δ_m increases compared to the state where it is not affected by other strings 15_m'. Considering the above tendency, the control device 61 determines whether the selected string 15_m is in a crosstalk state based on whether the differential voltage δ_m exceeds a predetermined threshold Vth1 (S5).

[0139] Specifically, when the differential voltage δ_m exceeds the threshold Vth1 (S5: Yes), the control device 61 determines that the selected string 15_m is in a crosstalk state and transfers the processing to step S16. On the other hand, when the differential voltage δ_m is below the threshold Vth1 (S5: No), the control device 61 determines that the selected string 15_m is not in a crosstalk state and transfers the processing to step S6. Furthermore, when the differential voltage δ_m is equal to the threshold Vth1, the determination result of the control device 61 can be either affirmative or negative.

[0140] Control device 61 selects the maximum value Cmax_m from the N voltages C_m,1 to C_m,N corresponding to the selection string 15_m (S6). As described above, since the voltage C_m,n increases due to pressing the string, the maximum value Cmax_m remains at a low voltage when the selection string 15_m is in the open state (the state where the string is not pressed). Taking into account the above tendency, control device 61 determines whether the selection string 15_m is in the open state based on whether the maximum value Cmax_m of the selection string 15_m is lower than a predetermined threshold Vth2 (S7).

[0141] Specifically, if the maximum value Cmax_m is lower than the threshold Vth2 (S7: Yes), the control device 61 determines that the selected string 15_m is in an open state and transfers the process to step S16. On the other hand, if the maximum value Cmax_m exceeds the threshold Vth2 (S7: No), the control device 61 determines that the selected string 15_m is not in an open state and transfers the process to step S16. Figure 27 Step S8. Furthermore, when the maximum value Cmax_m equals the threshold Vth2, the decision result of the control device 61 can be either positive or negative.

[0142] Control device 61 selects any one of the N wires 14_1 to 14_N (hereinafter referred to as "selected wire 14_n") (S8). For example, control device 61 initializes the number n of selected wire 14_n to "1". Each of the N wires 14_1 to 14_N is selected sequentially as selected wire 14_n in the negative direction of the Y-axis. Control device 61 determines whether processing has been performed on all N wires 14_1 to 14_N (S9).

[0143] In the case of an unselected wire 14_n (S9: No), the control device 61 calculates the detection voltage V_m,n corresponding to the selected string 15_m and the selected wire 14_n (S10). As described above, the detection voltage V_m,n is the difference between the voltage C_m,n in each supply period T_n and the reference voltage Cref_n (V_m,n = |C_m,n - Cref_n|). As explained above, the control device 61 (string analysis unit 60B) of the third embodiment functions as an element (voltage detection unit) for detecting the detection voltage V_m,n between each string 15_m and the return line 22.

[0144] For reference Figure 25 As mentioned above, there is a tendency for the detection voltage V_m,n to increase when the position corresponding to the selected fret 14_n is pressed. Taking into account the above tendency, the control device 61 determines whether the detection voltage V_m,n is lower than the predetermined threshold Vth3 (S11).

[0145] If the detected voltage V_m,n is lower than the threshold Vth3 (S11: Yes), the control device 61 sets the string pressing flag F_m,n to a value f0 (e.g., 0) (S12). Conversely, if the detected voltage V_m,n exceeds the threshold Vth3 (S11: No), the control device 61 sets the string pressing flag F_m,n to a value f1 (e.g., 1), which is different from the value f0 (S13). The string pressing flag F_m,n provides information for exploring the pressing position of the selection string 15_m. A value f0 for the string pressing flag F_m,n means that the selection fret 14_n and the return path 22 are not short-circuited. Conversely, a value f1 for the string pressing flag F_m,n means that the selection fret 14_n and the return path 22 are in contact due to string pressing.

[0146] Control device 61 adds "1" to the number n of the selected fret 14_n (S14). That is, the selected fret 14_n is changed. When the string pressing mark F_m,n has been set for all N frets 14_1 to 14_N, the judgment result in step S9 changes from negative to positive. Control device 61 uses the N string pressing marks F_m,1 to F_m,N corresponding to different frets 14_n to determine the pressing position of the selected string 15_m (S15). Specifically, control device 61 determines the pressing position of the selected string 15_m as the position corresponding to the boundary between the value f0 and the value f1 in the sequence of N string pressing marks F_m,1 to F_m,N. As explained above, the string pressing analysis unit 60B of the third embodiment determines the string pressing position of the fret 14_n that is in contact with the string 15_m among the N frets 14_1 to 14_N based on the change of the detection voltage V_m,n detected by the supply of each drive signal D.

[0147] exist Figure 26 In step S16, the control device 61 adds "1" to the number m of the selected string 15_m. That is, the selected string 15_m is changed. When the above processing has been performed on all five strings 15_1 to 15_5, the determination result in step S3 changes from negative to positive. As explained above, for each of the five strings 15_1 to 15_5, the presence or absence of the pressed string and its position (pressing position) are determined.

[0148] In the third embodiment, the same effect as in the first embodiment is achieved. Furthermore, in the third embodiment, the control device 61 executes a program to detect the string position corresponding to each detection voltage V_m,n. Therefore, compared to the first embodiment, it has the advantage of a simplified structure and operation of the detection device 30.

[0149] C: Fourth Implementation Method

[0150] Figure 28This is a block diagram illustrating the structure of the signal output unit 55 and the string analysis unit 60B in the fourth embodiment. In the fourth embodiment, a DC voltage B is applied to each of the five strings 15_1 to 15_5. The DC voltage B is a bias voltage maintained at a predetermined voltage value (e.g., 5V). For example, the signal supply unit 40 applies a DC voltage B to each string 15_m.

[0151] The signal output unit 55 of the fourth embodiment, like that of the first embodiment, includes five output circuits 56_1 to 56_5 corresponding to different strings 15_m, and an output circuit 57 corresponding to the return line 22. Each output circuit 56_m, like that of the first embodiment, generates a voltage C_m,n corresponding to the voltage C0_m,n of the string 15_m during the supply period T_n. Specifically, the output circuit 56_m includes: a DC removal circuit for removing the DC component (DC voltage B) from the voltage C0_m,n, and electrical circuits (e.g., an amplifier, a rectifier circuit, a smoothing circuit) for generating the voltage C_m,n based on the removed voltage.

[0152] Furthermore, in addition to the circuit described above that generates the voltage C_m,n corresponding to the voltage C0_m,n, the output circuit 56_m of the fourth embodiment also includes a comparator 58_m. The comparator 58_m compares the voltage C0_m,n, which includes the DC voltage B, with a predetermined threshold. The threshold is a predetermined voltage lower than the DC voltage B.

[0153] Comparator 58_m generates a binary signal W_m corresponding to the result of comparing the voltage C0_m,n with a threshold. When the voltage C0_m,n exceeds the threshold, comparator 58_m outputs a high-level signal W_m. Conversely, when the voltage C0_m,n is below the threshold, comparator 58_m outputs a low-level signal W_m.

[0154] When string 15_m is in the open state, since voltage C0_m,n is a high voltage approximately equal to DC voltage B, signal W_m is set to a high level. On the other hand, when string 15_m is connected to return line 22 due to string pressing, voltage C0_m,n drops to a voltage lower than DC voltage B. Therefore, signal W_m is set to a low level. As explained above, signal W_m is a binary signal indicating whether string 15_m is in the open state.

[0155] Each signal W_m is supplied to the string analysis unit 60B (control device 61). For each of the five strings 15_1 to 15_5, the control device 61 determines whether the string 15_n is in an open state based on the level of the signal W_m. Specifically, the control device 61 determines that the string 15_n is in an open state when the signal W_m is high, and determines that the string 15_n is not in an open state when the signal W_m is low. As explained above, the detection device 30 (signal output unit 55 and string analysis unit 60B) of the fourth embodiment functions as a string determination unit (string determination unit) that determines the presence or absence of a pressed string for each string 15_m based on the voltage C0_m,n of that string 15_m.

[0156] Furthermore, as described above, in the fourth embodiment, since the presence or absence of a pressed string for string 15_m is determined based on signal W_m, the process of determining whether string 15_m is in an open state in the pressed string analysis process can be omitted (S6, S7).

[0157] In the fourth embodiment, the same effects as in the first and third embodiments are achieved. Furthermore, the fourth embodiment has the advantage of being able to accurately determine the presence or absence of a pressing string on a string 15_m based on the voltage of each string 15_m to which a DC voltage B has been applied.

[0158] D: Fifth Implementation Method

[0159] Figure 29 This is a cross-sectional view of the neck 11 and fingerboard 12 in the fifth embodiment. Figure 29 The section orthogonal to the direction of the extension of the neck 11 (the direction of the Y-axis) and the section along that direction (the sections of line A-A and line B-B) are also recorded.

[0160] like Figure 29 As illustrated, in the fifth embodiment, the protrusion 141 of each fret 14_n is a flat, foot-like portion that protrudes from the bottom surface of the portion of the fret 14_n extending along the X-axis toward the neck 11 and the fingerboard 12, and extends along the X-axis between the two ends of the fret 14_n. That is, the protrusion 141 of the fifth embodiment is continuous throughout the width direction of the fret 14_n.

[0161] On the other hand, in addition to the mounting holes 122 similar to those in the first embodiment, mounting grooves 125 corresponding to each wire 14_n are formed on the surface of the finger plate 12. The mounting groove 125 is a bottomed groove that extends integrally along the X-axis direction throughout the width direction of the finger plate 12. A mounting hole 122 is formed in the center of the mounting groove 125 in the X-axis direction. The gap of the mounting groove 125 (the interval in the Y-axis direction) is smaller than the gap of the mounting hole 122.

[0162] like Figure 29 As illustrated in section B-B, the finger wire 14_n is fixed to the finger plate 12 by inserting the protrusion 141 into the mounting groove 125. That is, one side of the protrusion 141 contacts one inner wall surface of the mounting groove 125, and the other side of the protrusion 141 contacts the other inner wall surface of the mounting groove 125.

[0163] like Figure 29 As illustrated, in the fifth embodiment, the connecting portion 24_n in the above-described embodiments is replaced by a connecting portion 25_n. The connecting portion 25_n is a flexible conductor that can deform under external force. For example, a conductive foam whose surface is covered by a conductive film is used as the connecting portion 25_n.

[0164] Similar to the first embodiment, mounting holes 122 corresponding to each wire 14_n are formed on the finger plate 12. Connecting portions 25_n are inserted into the mounting holes 122. The lower surface of the connecting portion 25_n contacts the mounting surface 20a of the wiring substrate 20 and is electrically connected to the return line 22 on the mounting surface 20a. Furthermore, since the connecting portion 25_n is deformable, the planar shape of the mounting holes 122 is arbitrary. For example, in addition to forming mounting holes 122 that are rectangular when viewed from above, it is also envisioned that mounting holes 122 be formed on the finger plate 12 that are elliptical or oblong when viewed from above.

[0165] like Figure 29 As shown in the cross-section A-A, the central portion of the protrusion 141 of the wire 14_n, located inside the mounting hole 122, presses against the top surface of the connector 25_n. By being pressed by the protrusion 141, the connector 25_n partially deforms. Specifically, the protrusion 141 sinks into the connector 25_n. Therefore, the connector 25_n is held in a compressed state between the protrusion 141 and the wiring substrate 20. The lower surface of the connector 25_n may be bonded to the mounting surface 20a, for example, using a conductive bonding material, or it may not be bonded to the mounting surface 20a.

[0166] In the fifth embodiment, the wire 14_n is electrically connected to the wiring substrate 20 (return line 22) via a flexible connecting portion 25_n that deforms when pressed by the protrusion 141. Therefore, even if there are errors in the position or size of the wire 14_n, the wire 14_n can be reliably connected relative to the return line 22.

[0167] Furthermore, the protrusion 141 used to fix the fret 14_n to the fingerboard 12 also serves as the electrical connection between the fret 14_n and the return line 22. Therefore, it also has the advantage of being able to use the frets of existing stringed instruments, where the protrusion 141 extends throughout the width of the fret 14_n, in accordance with the present disclosure.

[0168] In addition, Figure 29 The example illustrates a method in which a wiring substrate 20 is housed in a groove 112 formed in the neck 11, but as... Figure 30 As illustrated, the wiring substrate 20 can also be housed in the groove 123 formed in the finger plate 12. Figure 30 In the structure, the surface of the neck 11 opposite to the fingerboard 12 is a flat surface with the groove 112 omitted.

[0169] Furthermore, in the structure where the wiring substrate 20 is housed in the groove 123 of the finger plate 12, such as Figure 31 As illustrated, a support member 124 can also be provided to close the opening of the groove 123. The support member 124 is a plate-shaped member (filler) formed to have the same shape as the groove 123 when viewed from above. The wiring substrate 20 is located between the bottom surface of the groove 123 in the finger plate 12 and the support member 124. Alternatively, the support member 124 can also be composed of a plurality of support plates spaced apart from each other in the longitudinal direction (Y-axis direction) of the groove 123. Each support plate is a member that extends along the X-axis direction across the sidewalls of the groove 123.

[0170] E: Variation Example

[0171] The following examples illustrate specific variations of the methods illustrated above. Alternatively, two or more methods selected from the following examples may be appropriately combined, provided they do not contradict each other.

[0172] (1) In the above embodiments, the signal supply unit 40 is shown to have a drive circuit 41_n for each drive coil 21_n, but the structure of the signal supply unit 40 is not limited to the above embodiments. For example, it may also be adopted Figure 32 The illustrated signal supply unit 40.

[0173] exist Figure 32 In this configuration, multiple (N) drive coils 21 are divided into K groups (hereinafter referred to as "drive coil groups") G_1 to G_K in units of a predetermined number. Furthermore, the number of drive coils 21 belonging to each drive coil group G_k (k = 1 to K) may be different. The signal supply unit 40 includes a drive circuit 41_k and a distribution circuit 48_k for each of the K drive coil groups G_1 to G_K.

[0174] Figure 32The selection signal S is a control signal that sequentially selects each of the K drive coil groups G_1 to G_K in a time-division manner. Each of the K drive coil groups G_1 to G_K is sequentially selected by the selection signal S in each selection period. During the selection period of the selected drive coil group G_k, the drive circuit 41_k outputs the drive signal D0. Furthermore, during the selection period of the selected drive coil group G_k, the distribution circuit 48_k outputs the drive signal D0 to each of the plurality of drive coils 21 belonging to the drive coil group G_k in a time-division manner. Figure 32 Compared with the above methods, the structure can reduce the number of drive circuits 41_k.

[0175] (2) In the above methods, an example is shown where the magnetic flux of each drive coil 21_n is linked to the corresponding detection coil 28_m of each of the five strings 15_1 to 15_5. In the above methods, each drive coil 21_n is shared by the five strings 15_1 to 15_5. However, it is also possible to form a separate drive coil 21_n for each of the five strings 15_1 to 15_5.

[0176] (3) In the above embodiments, the voltage detection unit 50 compares each detected voltage U_m with the reference voltage R, but the function of the voltage detection unit 50 is not limited to the above embodiments. For example, the function of comparing each detected voltage U_m with the reference voltage R, or the function of generating a detected voltage U_m corresponding to the detected voltage V_m, can be omitted from the voltage detection unit 50. As can be understood from the above embodiments, the voltage detection unit 50 can be simply described as an element that detects the detected voltage V_m.

[0177] (4) The shape and position of the return line 22 and the reference line 23 are not limited to the examples described above. For example, the return line 22 may be provided on the mounting surface 20a of the wiring substrate 20, and the reference line 23 may be provided on the surface opposite to the mounting surface 20a. In addition, the return line 22 and the reference line 23 may be provided on different wiring substrates. The return line 22 and the reference line 23 are not limited to conductive patterns, and may be formed by linear conductors, for example.

[0178] (5) In the above methods, an example is given where the reference voltage R, which is compared with the detection voltage U_m, varies according to the number of simultaneous chords. However, the reference voltage R can also be a fixed voltage. For example, as shown in... Figure 16 It is understood that by setting the reference voltage R to a fixed voltage of approximately 0.6 to 0.7V, the pressing position of each string 15_m can be detected even when multiple strings 15_m are pressed in parallel. However, from the viewpoint of accurately detecting the pressing position of each string 15_m when multiple strings 15_m are pressed in parallel, the aforementioned methods, in which the reference voltage R varies according to the number of strings pressed simultaneously, are preferred.

[0179] (6) The purpose of each output signal Z_m generated by the voltage detection unit 50 is arbitrary. For example, performance data specifying the string pressing position of the performer according to the time sequence can be generated and stored by analyzing each output signal Z_m. In addition, musical tones corresponding to the string pressing positions can also be reproduced.

[0180] (7) In the above methods, the example shown is that the driving signal D is supplied sequentially to each wire 14_n from the first wire 14_1 toward the Nth wire 14_N, but the order in which the driving signal D is supplied to each wire 14_n is not limited to the example shown above. For example, the driving signal D may also be supplied sequentially to each wire 14_n from the Nth wire 14_N toward the first wire 14_1. In addition, for example, the operation of supplying the driving signal D sequentially to each odd-numbered wire 14_n and the operation of supplying the driving signal D sequentially to each even-numbered wire 14_n may be performed alternately and repeatedly.

[0181] (8) In the first embodiment, a structure in which the protrusion 141 protrudes from the center of the filament 14_n is shown. Figure 8 ).like Figure 33 As illustrated, in the first embodiment where the return line 22 and the wire 14_n are connected using the connecting portion 24_n (connecting terminal or metal piece), the protrusion 141 can also extend integrally along the X-axis direction throughout the width direction of the wire 14_n, similar to the fourth embodiment. Furthermore, as... Figure 33 As illustrated, the wiring substrate 20 is housed in the groove 123 of the finger plate 12. Figure 30 The structure, and the opening of the groove 123, are closed by the support member 124. Figure 31 The same structure applies to the first implementation method.

[0182] (9) In the above embodiments, the electric bass 100 is exemplified as a stringed instrument, but the type of stringed instrument to which this disclosure applies is arbitrary. For example, in addition to the electric bass 100, this disclosure also applies to electric stringed instruments such as electric guitars. Furthermore, the stringed instruments to which this disclosure applies are not limited to electric stringed instruments that detect the vibration of each string electrically or magnetically. For example, this disclosure also applies to natural stringed instruments that produce sound through resonance in the internal space of the instrument body. That is, this disclosure can also be applied in order to detect and record the fingering performed by the performer in parallel with the normal performance of natural stringed instruments. As described above, this disclosure applies to any type of stringed instrument having frets 14-n that come into contact with the string 15-m when the performer presses the strings.

[0183] (10) In the above embodiments, the embodiment with five strings 15_m is conveniently illustrated, but the number of strings 15_m can be arbitrarily changed, for example, depending on the type of stringed instrument. Furthermore, this disclosure is also applicable to stringed instruments such as the mandolin, in which two strings 15_m played in parallel are provided as a pair and multiple pairs of strings 15_m are provided.

[0184] F: Postscript

[0185] From the examples above, for instance, grasp the following structure.

[0186] A stringed instrument according to one aspect (aspect 1) of this disclosure comprises: a neck; a plurality of conductive frets arranged at intervals along the neck; a plurality of conductive strings capable of contacting any one of the plurality of frets; a plurality of drive coils, each corresponding to one of the plurality of frets; a signal supply unit supplying a drive signal to each of the plurality of drive coils; a return path connected to each of the plurality of frets; and a voltage detection unit detecting a first detection voltage between a first string of the plurality of strings and the return path during the period when each of the plurality of drive coils is supplied with the drive signal.

[0187] In the above method, when current flows through each drive coil by supplying a drive signal, an electromotive force is generated in the detection coil, including the first string and the return line, by utilizing the mutual inductance of the magnetic field generated in the drive coil. Therefore, by detecting the first detection voltage between the first string and the return line, the fret that is in contact with the first string (i.e., the fingering position) among the multiple frets can be determined. According to the above structure, compared with the method of generating an electromotive force in the drive coil on the fingerboard by mutual inductance caused by supplying a drive signal to the string, the current flowing in the string is reduced. Therefore, the fingering position can be detected at high speed and with high accuracy while suppressing the influence on the detection of vibrations generated in the string due to playing (pickup).

[0188] A "drive signal" is a signal used to generate a magnetic field in a drive coil. A drive signal is, for example, a periodic signal that varies periodically with voltage. A drive signal is supplied sequentially to each of the multiple drive coils.

[0189] "First string" refers to any one string selected from the multiple strings of a stringed instrument, and is not limited to the lowest note. The number of strings on a stringed instrument is arbitrary. Furthermore, "stringed instrument" includes, for example, electric stringed instruments such as electric guitars or electric basses. However, "stringed instrument" is not limited to electric stringed instruments that detect the vibration of strings electrically or magnetically. That is, this disclosure also applies to natural stringed instruments that produce sound through resonance within the internal space of the instrument body.

[0190] In a specific example of Method 1 (Method 2), the return path is connected to the portion of the first string located closer to the front end of the neck than the plurality of frets, and the first detection voltage is the voltage between the portion of the first string located closer to the base end of the neck than the plurality of frets and the return path. According to the above method, it is possible to detect contact between the first string, which covers the entire neck, and any of the plurality of frets.

[0191] In a specific example of Method 1 or Method 2 (Method 3), the multiple strings include a second string, and the first string and the second string are connected to the return line. The voltage detection unit includes: a first detection circuit for detecting the first detection voltage; and a second detection circuit for detecting a second detection voltage between the second string and the return line. According to the above method, the first string and the second string are connected to a loop. Therefore, compared to a method where each of the first string and the second string is connected to its own independent loop, the structure of the stringed instrument can be simplified by reducing the number of loops.

[0192] In a specific example of Method 3 (Method 4), the magnetic field generated in each of the plurality of drive coils links with a first detection coil including the first string and the return path, and a second detection coil including the second string and the return path. In the above method, the drive coils are shared between the detection coil including the first string and the return path, and the detection coil including the second string and the return path. Therefore, compared to setting a separate drive coil for each string, the structure of the stringed instrument can be simplified by reducing the number of drive coils. Moreover, since the first string and the second string are connected to the return path, the size of the drive coils can be reduced compared to the method where the first string and the second string are connected to different return paths.

[0193] In a specific example of Method 3 or Method 4 (Method 5), the stringed instrument further comprises: a first resistive element connected between the portion of the first string located on the front side of the neck, closer than the plurality of frets, and the return path; and a second resistive element connected between the portion of the second string located on the front side of the neck, closer than the plurality of frets, and the return path. According to the above method, since a resistive element is connected between each of the first and second strings and the return path, the impedance of the detection coil can be ensured, and the impedance difference between the first and second strings can be reduced.

[0194] In a specific example (Method 6) of any of Methods 1 to 5, the stringed instrument further includes a fingerboard disposed on the neck, the plurality of frets disposed on the fingerboard, the fingerboard being located between the first string and the loop, and the plurality of drive coils being located between the fingerboard and the loop. In the above method, the plurality of drive coils are disposed between the fingerboard and the loop. That is, the plurality of drive coils are not exposed to the outside. Therefore, it is possible to maintain the appearance of the fingerboard while disposing of the drive coils.

[0195] In a specific example of Method 6 (Method 7), the stringed instrument includes: a wiring board disposed between the neck and the fingerboard; and a plurality of connecting portions disposed on the surface of the wiring board, the plurality of drive coils and the return line disposed on the wiring board, each of the plurality of frets including a protrusion inserted into the fingerboard, and each of the plurality of connecting portions being connected to the protrusion of the fret corresponding to the connecting portion. According to the above method, the protrusions of each fret inserted into the fingerboard are connected to the connecting portions of the wiring board. Therefore, each fret and the return line can be electrically connected using a simple structure that eliminates the need for wiring.

[0196] In a specific example of Method 7 (Method 8), each of the plurality of connecting portions is a flexible conductor that deforms when pressed by the protrusion. According to the above method, the plurality of filaments are electrically connected to the return line by the conductors compressed by the pressure from the protrusion. Therefore, even if there are errors in the position or size of each filament, the filament can be reliably connected relative to the return line.

[0197] In a specific example (method 9) of any of methods 1 to 8, the stringed instrument further includes a reference line that does not contact the plurality of frets. The reference line extends along the neck and connects to the loop path. The voltage detection unit detects a reference voltage between the reference line and the loop path and compares the first detected voltage with the reference voltage. In the above method, the reference voltage varies along with the first detected voltage depending on the number of strings in parallel contact with the frets. Therefore, by comparing the first detected voltage with the reference voltage, the fret in contact with the first string can be determined with high accuracy, regardless of the number of strings in parallel contact with the frets.

[0198] In a specific example of Method 9 (Method 10), the reference voltage varies according to the number of the pressed strings among the plurality of strings. In the above method, the reference line is configured such that the reference voltage varies according to the number of the pressed strings among the plurality of strings. Therefore, as described above, the fret in contact with the first string can be determined with high precision regardless of the number of strings in parallel contact with the fret.

[0199] In a specific example (method 11) of any of methods 1 to 10, the stringed instrument further includes a string-pressing analysis unit that determines the pressing position of the first string based on the change in the first detection voltage detected by each supply of the drive signal. According to the above method, the pressing position can be determined with high precision.

[0200] In a specific example (method 12) of any of methods 1 to 11, each of the plurality of strings is subjected to a predetermined DC voltage, and the stringed instrument further includes a string-pressing determination unit, which determines whether a string is pressed based on the voltage of each of the plurality of strings. According to the above method, the presence or absence of a string being pressed can be accurately determined based on the voltage of each string to which a DC voltage has been applied.

[0201] In order to electrically or magnetically determine which fret is in contact with the string among a plurality of frets, a structure is needed for electrically connecting the plurality of frets to wiring. In view of the above, a stringed instrument according to one aspect (aspect A) of the present disclosure comprises: a neck; a fingerboard disposed on the neck; a plurality of conductive frets arranged at intervals on the fingerboard; a plurality of conductive strings capable of contacting any one of the plurality of frets; and wiring connected to each of the plurality of frets.

[0202] In a specific example of method A (method B), the method includes: a wiring substrate disposed between the neck and the fingerboard, and a plurality of connecting portions disposed on the surface of the wiring substrate. The wiring is disposed on the wiring substrate, and each of the plurality of frets includes a protrusion inserted into the fingerboard. Each of the plurality of connecting portions is connected to the protrusion of the fret corresponding to that connecting portion. According to the above method, the protrusion of each fret inserted into the fingerboard is connected to the connecting portion of the wiring substrate. Therefore, each fret can be electrically connected to the wiring using a simple structure that eliminates the need for wiring.

[0203] In a specific example of method A (method C), each of the plurality of connecting portions is a flexible conductor that deforms when pressed by the protrusion. According to the above method, the plurality of filaments are electrically connected to the wiring by the conductors compressed by the pressure from the protrusion. Therefore, even if there are errors in the position or size of each filament, the filament can reliably conduct relative to the wiring.

[0204] Explanation of reference numerals in the attached figures

[0205] 100... Electric Bass, 10... Body, 11... Neck, 12... Fretboard, 13... Headstock, 14_n (14_1~14_N)... Frets, 15_m (15_1~15_5)... Strings, 16... Tuning Pins, 17... Bridge, 18... Nut, 19... Pickup, 20... Wiring Board, 20a... Mounting Surface, 21_n (21_1~21_N)... Drive Coil, 22... Return Wire, 23... Reference Wire, 24_n (24_1~24_N), 25_n (25_1~25_N)... Connector, 28_m (28_1~28_5)... Detection Coil, 30... Detection device, 40... Signal supply unit, 41_n (41_1~41_N)... Drive circuit, 42... Signal line, 43... Capacitor, 44... Low-pass filter, 45... Resistor element, 46... Capacitor, 47... Common line, 48_k (48_1~48_K)... Distribution circuit, 50... Voltage detection unit, 51_m (51_1~51_5)... Resistor element, 52_m (52_1~52_5)... Detection unit, 53... Output circuit, 54... Reference unit, 55... Signal output unit, 60A, 60B... String analysis unit, 71... Differential circuit, 72... Amplifier circuit.

Claims

1. A stringed instrument, possessing: Neck; Multiple conductive frets are arranged at intervals along the neck of the instrument; Multiple conductive strings are capable of contacting any one of the multiple filaments; Multiple drive coils, each corresponding to one of the multiple wires; The signal supply unit supplies a drive signal to each of the plurality of drive coils; The return path, connected to each of the plurality of filaments; as well as The voltage detection unit detects a first detection voltage between the first string of the plurality of strings and the return line during the period when the drive signal is supplied to each of the plurality of drive coils.

2. The stringed instrument according to claim 1, wherein, The return path is connected to the portion of the first string located closer to the front end of the neck than the plurality of frets. The first detection voltage is the voltage between the portion of the first string located closer to the base end of the neck than the plurality of frets and the loop path.

3. The stringed instrument according to claim 1, wherein, The multiple strings include a second string. The first string and the second string are connected to the return path. The voltage detection unit includes: A first detection circuit detects the first detection voltage; and The second detection circuit detects the second detection voltage between the second string and the return line.

4. The stringed instrument according to claim 3, wherein, The magnetic field generated in each of the plurality of drive coils links with a first detection coil including the first string and the return path, and a second detection coil including the second string and the return path.

5. The stringed instrument according to claim 3, wherein, The stringed instrument also features: A first resistive element is connected between the portion of the first string located on the front side of the neck, which is closer to the frets than the plurality of frets, and the loop path. as well as The second resistive element is connected in the second string, between the portion located on the front side of the neck that is closer to the frets than the plurality of frets, and the loop.

6. The stringed instrument according to claim 1, wherein, The stringed instrument also has a fingerboard, which is mounted on the neck. The plurality of filaments are disposed on the finger plate. The fingerboard is located between the first string and the return path. The plurality of drive coils are located between the finger plate and the return line.

7. The stringed instrument according to claim 6, wherein, The stringed instruments include: A wiring board is disposed between the neck and the fingerboard; and Multiple connecting portions are disposed on the surface of the wiring substrate. The plurality of drive coils and the return line are disposed on the wiring substrate. Each of the plurality of filaments includes a protrusion that inserts into the finger plate. Each of the plurality of connecting portions is connected to the protrusion of the filament corresponding to the connecting portion in the plurality of filaments.

8. The stringed instrument according to claim 7, wherein, Each of the plurality of connecting portions is a flexible conductor that deforms when pressed by the protrusion.

9. The stringed instrument according to claim 1, wherein, The stringed instrument also includes a reference line, which does not contact the plurality of frets. The reference line extends along the neck of the instrument and connects to the loop line. The voltage detection unit detects the reference voltage between the reference line and the return line, and compares the first detected voltage with the reference voltage.

10. The stringed instrument according to claim 9, wherein, The reference voltage varies according to the number of the pressed strings among the multiple strings.

11. The stringed instrument according to claim 1, wherein, The stringed instrument also includes a string pressing analysis unit, which determines the pressing position of the first string based on the change of the first detection voltage detected by the supply of each of the driving signals.

12. The stringed instrument according to claim 1, wherein, Each of the multiple strings is subjected to a specified DC voltage. The stringed instrument also includes a string pressing determination unit, which determines whether a string has been pressed based on the voltage of each of the plurality of strings.

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