Displacement sensor and electronic musical instrument

Abstract

The displacement sensor includes: a detected section including a first coil, the detected section being provided on a movable member that displaces in accordance with an operation; and a signal generation unit that includes a second coil facing the first coil and that generates a detection signal corresponding to the relative position between the first coil and the second coil, the outer dimension of the first coil in the first direction being different from the outer dimension of the first coil in a second direction orthogonal to the first direction in plan view.

Description

[0001] This application is a divisional application of Chinese National Application No. 202180021497.3 (Displacement Sensor and Electronic Musical Instrument) filed on March 18, 2021, and the content thereof is incorporated herein by reference. Technical Field

[0002] The present invention relates to a displacement sensor and an electronic musical instrument. Background Art

[0003] Conventionally, various techniques for detecting the displacement of a movable part such as a key of a keyboard instrument have been proposed. For example, Patent Document 1 discloses a structure in which a coil provided on a frame of a keyboard instrument and a metal plate provided on each key are used to detect the position of each key. In this structure, when the metal plate is displaced due to a key operation, the current flowing through the coil changes. By detecting the current flowing through the coil, a detection signal reflecting the displacement of the key operation is generated.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 3-48295 Summary of the Invention

[0005] However, in the technique of Patent Document 1, it is difficult to generate a detection signal that accurately reflects the displacement of the movable part. In view of such a situation, an object of one aspect of the present invention is to generate a detection signal that accurately reflects the displacement of the movable part.

[0006] A displacement sensor according to one aspect of the present invention includes: a detected portion provided on a movable part that is displaced in response to an operation, including a first coil; and a signal generation portion including a second coil opposed to the first coil, generating a detection signal corresponding to a relative position between the first coil and the second coil, wherein an outer dimension of the first coil in a first direction and an outer dimension of the first coil in a second direction orthogonal to the first direction are different when viewed from above.

[0007] A displacement sensor according to another aspect of the present invention has: a detected portion provided on a movable part that is displaced in response to an operation, including a first coil; and a signal generation portion including a second coil opposed to the first coil, generating a detection signal corresponding to a relative position between the first coil and the second coil, wherein the first coil has a first portion and a second portion that generate magnetic fields in opposite directions when a current is supplied to the first coil, the second coil has a third portion and a fourth portion that generate magnetic fields in opposite directions when a current is supplied to the second coil, and a first distance between a center of the first portion and a center of the second portion is greater than a second distance between a center of the third portion and a center of the fourth portion. Description of the Drawings

[0008] Figure 1 It is a block diagram showing an example of the structure of a keyboard instrument to which a displacement sensor related to one method is applied.

[0009] Figure 2 It is a block diagram showing an example of the structure of a keyboard instrument.

[0010] Figure 3 It is a diagram showing the circuit of the main part of the displacement sensor.

[0011] Figure 4 It is a block diagram illustrating an example of a signal processing circuit.

[0012] Figure 5 It is a top view showing the specific structure of the detected part.

[0013] Figure 6 It is Figure 5 A sectional view taken along line A - a of

[0014] Figure 7 It is an explanatory diagram of a magnetic field or the like generated by the first coil of the detected part.

[0015] Figure 8 It is a top view illustrating the specific structure of the signal generation part.

[0016] Figure 9 It is Figure 8 A sectional view taken along line B - b of

[0017] Figure 10 It is an explanatory diagram of a magnetic field generated by the second coil of the signal generation part.

[0018] Figure 11 It is a diagram illustrating the positional relationship between the first coil and the second coil.

[0019] Figure 12 It is a top view showing the structure of the detected part related to the comparative example.

[0020] Figure 13 It is a top view showing the structure of the detected part related to the comparative example.

[0021] Figure 14 It is a diagram showing an example of the output characteristics of the detection signal.

[0022] Figure 15 It is a diagram showing an example of the output characteristics of the detection signal.

[0023] Figure 16 It is a diagram showing an example of the output characteristics of the detection signal.

[0024] Figure 17 This is a diagram showing an example of the output characteristics of the detection signal.

[0025] Figure 18 This is a diagram showing the displacement sensor involved in the modification example being applied.

[0026] Figure 19 This is a diagram showing the displacement sensor involved in the modification example being applied. Detailed implementation mode

[0027] A: Implementation mode

[0028] Figure 1 This is a block diagram showing the structure of the keyboard instrument 100 to which the displacement sensor according to one aspect of the present invention is applied.

[0029] The keyboard instrument 100 is an electronic musical instrument having a keyboard 10, a detection system 15, an information processing device 30, and a sound playback device 40. The keyboard 10 is composed of a plurality of keys 12 including a plurality of white keys and a plurality of black keys. Each of the plurality of keys 12 is a movable member that is displaced corresponding to the playing action of the user. The detection system 15 detects the displacement (position) of the keys 12. The information processing device 30 generates a sound signal V corresponding to the result detected by the detection system 15. The sound signal V is a signal representing a musical tone corresponding to the pitch of the key 12 operated by the user. The sound playback device 40 plays back the sound represented by the sound signal V. For example, a speaker or headphones are used as the sound playback device 40.

[0030] Figure 2 This is a block diagram showing the specific structure of the keyboard instrument 100 by focusing on one key 12 in the keyboard 10. Each key 12 of the keyboard 10 is supported by a support member 14 with a fulcrum portion 13 as a fulcrum. The support member 14 is a structure that supports each element of the keyboard instrument 100. The end portion 121 of each key 12 is displaced in the vertical direction by the user pressing and releasing the key. The detection system 15 generates a detection signal D having a level corresponding to the position Z of the end portion 121 in the vertical direction for each of the plurality of keys 12. The position Z is expressed, for example, as the displacement amount of the end portion 121 with respect to the position of the end portion 121 in the released state where no load is applied to the key 12 as a reference.

[0031] The detection system 15 is provided with a displacement sensor 20 for each key 12 and a signal processing circuit 21 common to the keys 12. The displacement sensor 20 is a position sensor that detects the position of each key 12 and includes a detected portion 50 and a signal generation portion 60. The signal generation portion 60 is provided on the support member 14. The detected portion 50 is provided on the key 12. Specifically, the detected portion 50 is provided on the bottom surface (hereinafter referred to as the "installation surface") 122 of the key 12. The detected portion 50 includes a first coil 51. The signal generation portion 60 includes a second coil 61. The first coil 51 and the second coil 61 face each other at an interval in the vertical direction. The distance between the signal generation portion 60 and the detected portion 50 (the distance between the first coil 51 and the second coil 61) changes corresponding to the change in the position Z of the end portion 121 of the key 12 caused by pressing and releasing the key. The signal processing circuit 21 generates a detection signal D having a level corresponding to the distance between the first coil 51 and the second coil 61.

[0032] The information processing device 30 analyzes the position Z of each key 12 by analyzing the detection signal D supplied from the signal processing circuit 21. The information processing device 30 is implemented by a computer system having a control device 31, a storage device 32, an A / D converter 33, and a sound source circuit 34.

[0033] The A / D converter 33 converts the detection signal D supplied from the signal processing circuit 21 from analog to digital.

[0034] The control device 31 is composed of one or more processors that control each element of the keyboard instrument 100. For example, the control device 31 is composed of one or more processors such as a CPU (Central Processing Unit), an SPU (Sound Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit).

[0035] The control device 31 analyzes the position Z of each key 12 by analyzing the detection signal D converted by the A / D converter 33. In addition, the control device 31 gives an instruction to sound a musical tone corresponding to the position Z of each key 12 to the sound source circuit 34. The sound source circuit 34 generates an audio signal V representing the musical tone instructed from the control device 31. That is, the sound source circuit 34 detects that the key has reached a specified position corresponding to the voltage level δ of the detection signal D and starts generating the audio signal V. Moreover, for example, the volume of the audio signal V is controlled corresponding to the speed change of the voltage level δ. By supplying the audio signal V from the sound source circuit 34 to the sound playback device 40, the sound playback device 40 plays back the musical tone corresponding to the playing action of the user. Specifically, the musical tone is played back by pressing each key 12 by the user, and the musical tone is stopped by releasing the key 12.

[0036] The storage device 32 is one or more memories that store the programs executed by the control device 31 and the data used by the control device 31. The storage device 32 is constituted by a known recording medium such as a magnetic recording medium or a semiconductor recording medium, for example. In addition, the storage device 32 may be constituted by a combination of a plurality of recording media. Further, a mobile recording medium that can be attached to and detached from the keyboard instrument 100, or an external recording medium (such as a network hard disk) that can communicate with the keyboard instrument 100 may be used as the storage device 32. In addition, the function of the sound source circuit 34 can be realized by the control device 31 executing the program stored in the storage device 32. The sound source circuit 34, or the control device 31 that realizes the function of the sound source circuit 34, functions as a sound control unit that generates the audio signal V corresponding to the voltage level δ of the detection signal D.

[0037] Figure 3 It is a circuit diagram illustrating the electrical structure of the detected portion 50 and the signal generation portion 60 constituting the displacement sensor 20.

[0038] The signal generation portion 60 includes an input terminal T1, an output terminal T2, a second coil 61, a capacitor element 62, a capacitor element 63, and a resistor element 64. In the signal generation portion 60, a resonance circuit is constituted by the second coil 61, the capacitor element 62, the capacitor element 63, and the resistor element 64. The input terminal T1 is connected to one end of the resistor element 64, and the other end of the resistor element 64 is connected to one end of the capacitor element 62 and one end of the second coil 61. The other end of the second coil 61 is connected to the output terminal T2 and one end of the capacitor element 63. The other ends of the capacitor element 62 and the capacitor element 63 are grounded to the reference of zero voltage, that is, the potential Gnd.

[0039] On the other hand, the detected portion 50 includes a first coil 51 and a capacitive element 52. One end of the first coil 51 and one end of the capacitive element 52 are connected to each other, and the other end of the first coil 51 and the other end of the capacitive element 52 are connected to each other. A resonant circuit is formed by the first coil 51 and the capacitive element 52. The resonant frequency of the signal generation unit 60 is set, for example, based on the relationship with the resonant frequency of the detected portion 50. The set resonant frequency of the signal generation unit 60 is, for example, set to a frequency substantially the same as the resonant frequency of the detected portion 50, or a frequency obtained by multiplying the resonant frequency of the detected portion 50 by a predetermined constant.

[0040] A reference signal R is supplied to the input terminal T1 of the signal generation unit 60. The reference signal R is a voltage signal whose level changes periodically. For example, a periodic signal having an arbitrary waveform such as a sine wave is used as the reference signal R. The frequency of the reference signal R is set based on the relationship with the resonant frequency of the detected portion 50, etc. For example, the frequency of the reference signal R is substantially equal to the resonant frequencies of the signal generation unit 60 and the detected portion 50.

[0041] By supplying a current corresponding to the reference signal R to the second coil 61, a magnetic field is generated in the second coil 61. An induced current is generated in the first coil 51 by electromagnetic induction caused by the magnetic field generated in the second coil 61. Therefore, a magnetic field is generated in the first coil 51 in a direction that cancels the change in the magnetic field of the second coil 61. The magnetic field generated in the first coil 51 changes corresponding to the distance dr between the first coil 51 and the second coil 61. Therefore, a detection signal d having a voltage level δ (peak-to-peak value) corresponding to the distance dr between the first coil 51 and the second coil 61 is output from the output terminal T2 of the signal generation unit 60. The detection signal d is a periodic signal whose level changes with the same period as the reference signal R.

[0042] Figure 4 FIG. is a block diagram illustrating the specific configuration of the signal processing circuit 21. The signal processing circuit 21 includes a supply circuit 22 and an output circuit 23. The supply circuit 22 supplies the reference signal R to each of the input terminals T1 of the plurality of signal generation units 60. The supply circuit 22 supplies the reference signal R to the respective signal generation units 60 in a time-division manner. Specifically, the supply circuit 22 is a demultiplexer that sequentially selects each of the plurality of signal generation units 60 and supplies the reference signal R to the selected signal generation unit 60. That is, the reference signal R is supplied to each of the plurality of signal generation units 60 in a time-division manner. In addition, the period of the reference signal R is sufficiently shorter than the time length of the period during which the supply circuit 22 selects one signal generation unit 60.

[0043] The output circuit 23 generates a detection signal D by arranging the detection signals d output in sequence from each of the plurality of signal generation units 60 on the time axis. That is, the detection signal D is a signal of the voltage level δ corresponding to the distance dr between the first coil 51 and the second coil 61 for each key 12. As described above, the distance dr between the first coil 51 and the second coil 61 is related to the position Z of each key 12, so the detection signal D becomes a signal corresponding to the position Z of each of the plurality of keys 12. That is, when viewed through one key 12, the detection signal d appears as a signal corresponding to the relative position between the first coil 51 and the second coil 61, and the second coil 61 faces the first coil 51. The detection signal D generated by the output circuit 23 is supplied to the information processing device 30.

[0044] Next, the structures of the detected portion 50 and the signal generation unit 60 will be described.

[0045] Figure 5 It is a top view showing the specific structure of the detected portion 50 and is a view of the detected portion 50 as viewed from the signal generation unit 60 side. Figure 6 It is Figure 5 a cross-sectional view taken along line A - a of

[0046] The detected portion 50 includes a substrate 551 and wiring patterns provided on the surface F1 and the surface F2 of the substrate 551. As an example, the substrate 551 is a rectangular plate-like member having insulating properties. The surface F1 of the detected portion 50 is the surface on which the setting surface 122 of the key 12 is mounted. The wiring pattern of the detected portion 50 is formed by patterning a conductive layer such as a copper foil provided on the surfaces F1 and F2 of the substrate 551.

[0047] In addition, in Figure 5 , the vertical direction is the direction in which the plurality of keys 12 are arranged, and the horizontal direction is the length direction of one key 12. The width Bw of the detected portion 50 mounted on the setting surface 122 of the key 12 is less than or equal to the width Kw of one key 12.

[0048] Further, the surface F2 is the surface on the opposite side of the surface F1. Therefore, the surface F2 faces the signal generation unit 60. The first coil 51 of the detected portion 50 is composed of a first portion 521 and a second portion 522. The first portion 521 and the second portion 522 are part of the wiring pattern formed on the surface F2 of the substrate 551. The first portion 521 is a portion formed in a spiral shape. The second portion 522 is a portion formed in substantially the same shape as the first portion 521. That is, the second portion 522 is formed in a spiral shape in the same direction as the winding direction of the first portion 521.

[0049] The center of the vortex of the first part 521 is the via hole C1, and the center of the vortex of the second part 522 is the via hole C2. The via hole C1 and the via hole C2 are electrically connected through the wiring pattern 515 on the surface F1.

[0050] In the present embodiment, in the vortex of the first part 521, a straight line extending from the via hole C1 bends approximately 90 degrees and expands outward. The outer shape of the first part 521 is rectangular. Similarly, for the vortex of the second part 522, a straight line extending from the via hole C2 bends approximately 90 degrees and expands outward. The outer shape of the second part 522 is rectangular.

[0051] The outer shapes of the first part 521 and the second part 522 are rectangular. Figure 5 For each of the first part 521 and the second part 522, the outer dimension COL in the long side direction of the substrate 551 and the outer dimension COW in the short side direction of the substrate 551 are shown. The outer dimension COW corresponds to the size of the first coil 51 in the short side direction of the substrate 551. The outer dimension COW of each of the first part 521 and the second part 522 is less than or equal to the dimension Bw of the substrate 551 in the short side direction. The long side direction of the substrate 551 is the same as the length direction of the key 12, which is the arrangement direction of the first part 521 and the second part 522. In addition, the short side direction of the substrate 551 is the same as the lateral direction of the key 12, and the lateral direction of the key 12 is the direction orthogonal to the arrangement direction of the first part 521 and the second part 522.

[0052] In addition, the via hole C1 is located at the center of the first part 521. This center is the point where the diagonals of the rectangular outer shape of the first part 521 intersect. Similarly, the via hole C2 is located at the center of the second part 522. This center is the point where the diagonals of the rectangular outer shape of the second part 522 intersect.

[0053] In addition, the distance between the center (via hole C1) of the first part 521 and the center (via hole C2) of the second part 522 is set as L1. In addition, the distance L1 is an example of the first distance.

[0054] When one end of the first part 521 is the via hole C1 and the other end of the second part 522 is the via hole C2, the capacitor element 52 is installed between them. Therefore, the equivalent circuit of the detected part 50 becomes a structure in which the capacitor element 52 is connected to both ends of the first coil 51 as shown in Figure 3 the figure.

[0055] In addition, in the present embodiment, the first part 521 and the second part 522 are set to have the same size and the same shape, but are not limited thereto. For example, the shape or size may also be different between the first part 521 and the second part 522. Further, the planar shape of one or both of the first part 521 and the second part 522 may be set to Figure 5 a rectangular shape in which the longitudinal direction of Figure 5 is the length direction and the lateral direction of

[0056] Figure 8 is a top view showing the specific structure of the signal generation unit 60 and is a view of the signal generation unit 60 observed from the side of the detection unit 50. In addition, Figure 9 is Figure 8 a cross-sectional view taken along line B-b of

[0057] The signal generation unit 60 includes a substrate 651 and wiring patterns provided on the surface F3 and the surface F4 of the substrate 651. The substrate 651 is a plate-like member having insulating properties. The surface F4 of the signal generation unit 60 faces the support member 14. The surface F3 is the surface on the opposite side of the surface F4 and faces the detection unit 50. The wiring patterns are formed by patterning a conductive layer such as a copper foil provided on the surfaces F3 and F4 of the substrate 651.

[0058] Figure 8 The up-down direction of Figure 8 is the direction in which a plurality of keys 12 (not shown in Figure 8 are arranged. The left-right direction of

[0059] is the length direction of one key 12. The length direction of the key 12 is the direction from the front end side (the side of the performer) of the key 12 toward the root side of the key 12.

[0060] The second coil 61 of the signal generation unit 60 is composed of a third part 621 and a fourth part 622. The third part 621 and the fourth part 622 are parts of the wiring pattern formed on the surface F3. The third part 621 is a substantially square-shaped part formed in a spiral shape. The fourth part 622 is a part formed in substantially the same shape as the third part 621. That is, the fourth part 622 is formed in a spiral shape in the same direction as the winding direction of the third part 621.

[0061] In addition, in the present embodiment, the third part 621 and the fourth part 622 are set to have the same size and the same shape, but it is not limited thereto. For example, the sizes may be different between the third part 621 and the fourth part 622. Additionally, the third part 621 and the fourth part 622 may be set to have different shapes from each other. Moreover, the planar shape of the second coil 61 is not limited to the shape including the third part 621 and the fourth part 622. That is, the second coil 61 may be constituted by one winding part.

[0062] In the present embodiment, the outer shape of the third part 621 is substantially square. Similarly, the outer shape of the fourth part 622 is substantially square.

[0063] The direction of one side of the square, which is the outer shape of the third part 621 and the fourth part 622, is consistent with the length direction of the key 12, and the direction orthogonal to the one side is consistent with the lateral direction of the key 12. The size (outer dimension) of one side of the square is set as B2.

[0064] In addition, the through-hole C11 is located at the center of the third part 621, and the through-hole C12 is located at the center of the fourth part 622. The center mentioned here is the center of the coil when viewed from above. If it is a square or a rectangle, it is the point where the diagonals intersect. If it is a circle, it is the center of the outer circle.

[0065] Furthermore, the distance between the center of the third part 621 (in the present embodiment, the through-hole C11) and the center of the fourth part 622 (in the present embodiment, the through-hole C12) is set as L2. In addition, the distance L2 is an example of the second distance.

[0066] The part other than the second coil 61 in the wiring pattern of the surface F3 is the wiring for connecting the capacitor element 62, the capacitor element 63, the resistor element 64, the input terminal T1, and the output terminal T2. As described above, the reference signal R is supplied from the supply circuit 22 to the input terminal T1, and the detection signal d of the voltage level δ corresponding to the distance dr between the first coil 51 and the second coil 61 is output from the output terminal T2.

[0067] In the above structures of the detected part 50 and the signal generation part 60, the first part 521 and the third part 621 face each other, and the second part 522 and the fourth part 622 face each other. Moreover, as an example, the dimensional relationship becomes COW = B2 × 70%, COL = B2.

[0068] Next, the operation of the circuits of the detected part 50 and the signal generation part 60 will be described. Figure 7 This is a diagram showing an example of the magnetic field direction generated by the detected part 50. Figure 10 This is a diagram showing an example of the magnetic field direction generated by the signal generation part 60.

[0069] By supplying the reference signal R to the signal generation unit 60, for example, when a current flows counterclockwise through the third part 621 starting from the via hole C11 in Figure 8 a current flows clockwise through the fourth part 622 toward the via hole C12. Therefore, in the third part 621, a magnetic field is generated in the direction toward the front of the paper surface of Figure 8 and the upward direction of Figure 10 , and in the fourth part 622, a magnetic field is generated in the direction toward the depth of the paper surface of Figure 8 and the downward direction of Figure 10 .

[0070] That is, as Figure 10 illustrates, magnetic fields in opposite directions are generated in the third part 621 and the fourth part 622. As described above, in the keyboard 10, a plurality of keys 12 are arranged in the direction perpendicular to the paper surface of Figure 10 . Therefore, magnetic fields in opposite directions are generated in the third part 621 and the fourth part 622, thereby reducing the diffusion of the magnetic field generated in the signal generation unit 60 opposite to each adjacent key 12. As a result of reducing the diffusion of the magnetic field, a detection signal D that accurately reflects the positions Z of the plurality of keys 12 is generated.

[0071] In addition, in Figure 10 , an example is shown where a current flows counterclockwise in the third part 621 and a current flows clockwise in the fourth part 622 in Figure 8 . When a current flows clockwise in the third part 621 and a current flows counterclockwise in the fourth part 622, the direction of the magnetic field is also opposite.

[0072] The third part 621 and the fourth part 622 of the second coil 61 of the signal generation unit 60 are formed by patterning the conductive layer on the surface F4. Therefore, there is an advantage that, for example, compared with a structure in which the second coil 61 is formed by winding a conductive wire, the manufacturing and operation of the second coil 61 are easier.

[0073] As described above, in a state where the reference signal R is supplied to the signal generation unit 60, when the first coil 51 moves in a direction away from the second coil 61, a magnetic field in a direction that prevents the magnetic field generated by the second coil 61 from decreasing is generated in the first coil 51 (that is, a magnetic field in the same direction as the magnetic field generated by the second coil 61). Therefore, in this case, a current corresponding to the magnetic field in the same direction as the magnetic field generated by the second coil 61 is excited in the first coil 51.

[0074] For example, when a magnetic field is generated by the second coil 61 of the signal generation unit 60 Figure 10In a state where a magnetic field is in the direction shown, when the first coil 51 of the detected portion 50 moves in a direction away from the second coil 61, a magnetic field having the same direction as the magnetic field generated by the second coil 61 is generated in the first coil 51.

[0075] Therefore, in Figure 5 , in the first portion 521 of the first coil 51, current flows clockwise, and in the second portion 522, current flows counterclockwise.

[0076] In addition, in a state where a magnetic field in the direction shown is generated by the second coil 61 of the signal generation unit 60, when the first coil 51 of the detected portion 50 moves in a direction approaching the second coil 61, a magnetic field having a direction opposite to the magnetic field generated by passing through the second coil 61 is generated in the first coil 51. Figure 10

[0077] Therefore, in Figure 5 , in the first portion 521 of the first coil 51, current flows counterclockwise, and in the second portion 522, current flows clockwise.

[0078] Furthermore, in a state where the second coil 61 generates a magnetic field in a direction opposite to the direction Figure 10 illustrated, when the first coil 51 approaches the second coil 61, a magnetic field having a direction opposite to the magnetic field generated by passing through the second coil 61, that is, a magnetic field as Figure 7 shown, is generated in the first coil 51.

[0079] In addition, in a case where the first coil 51 approaches the second coil 61 in a state where a magnetic field in the direction shown is generated by the second coil 61, and in a case where the first coil 51 moves away from the second coil 61 in a state where the second coil 61 generates a magnetic field in a direction opposite to the direction Figure 10 shown, in the first portion 521 of the first coil 51, current flows clockwise, and in the second portion 522, current flows counterclockwise. Figure 10

[0080] Next, a structure and process for improving the linearity related to the output characteristics of the detection signal, that is, extending the detection distance, in the detection system 15 will be described. The output characteristics are the relationship between the distance dr and the voltage level δ of the detection signal, where the distance dr is the distance between the first coil 51 and the second coil 61. The linearity of the output characteristics means that the relationship between the voltage level δ and the distance dr is close to a proportional relationship. In addition, the detection distance is the amplitude of the range (detection range) of the distance dr in which the voltage level δ effectively changes with respect to the change in the distance dr. That is, the detection distance is the range of the distance dr reflected in the voltage level δ.

[0081] ​​In order to improve the linearity of the output characteristics, in the present embodiment, the distance L1 (the first distance) between the center of the first part 521 and the center of the second part 522 is greater than the distance L2 (the second distance) between the center of the third part 621 and the center of the fourth part 622.

[0082] Figure 11 FIG. is a plan view showing the positional relationship between the first coil 51 and the second coil 61 in a state where the detected portion 50 is mounted on the mounting surface 122 of the key 12 and the signal generation portion 60 is provided on the support member 14. Specifically, Figure 11 FIG. is a plan view showing a perspective view of the first part 521 and the second part 522 of the first coil 51 and the third part 621 and the fourth part 622 of the second coil 61 from the detected portion 50 toward the signal generation portion 60 in the above state.

[0083] The through holes C1, C2, C11, and C12 are located on a straight line Ln along the length direction of the key 12. In addition, the through holes C11 and C12 are located between the through hole C1 and the through hole C2.

[0084] In the displacement sensor 20 according to the present embodiment, the distance L1 between the center of the first part 521 of the detected portion 50 and the center of the second part 522 is greater than the distance L2 between the center of the third part 621 of the signal generation portion 60 and the center of the fourth part 622. Here, first, the effectiveness of the structure in which the distance L1 is greater than the distance L2 will be described.

[0085] The output characteristics are compared between the structure A and the structure B in which the magnitudes of the distance L1 and the distance L2 are different. The structure A is as Figure 12 shown, and is a structure in which the distance L1 of the first coil 51 is greater than the distance L2. The structure B is as Figure 13 shown, and is a structure in which the distance L1 of the first coil 51 is less than the distance L2.

[0086] Specifically, in Figure 12 , the distance L1 is Figure 8 L2 × 120% as shown, and in Figure 13 , the distance L1 is L2 × 80%. In addition, Figure 12 the outer dimensions COL and COW of Figure 13 and Figure 8 the outer dimensions COL and COW of Figure 8 are lengths of the outer dimensions B2 × 70% as shown. The signal generation portion 60 used for this comparison has

[0087] Figure 14 FIG. is a diagram showing the output characteristics of the displacement sensors 20 of the structure A and the structure B. In Figure 14, the vertical axis is the voltage level δ [V] of the detection signal d, and the horizontal axis is the distance corresponding to the position of the displacement Z, specifically the distance dr between the first coil 51 and the second coil 61. Additionally, in Figure 14 , the solid line represents Figure 12 the output characteristics of the structure A shown, and the dashed line represents Figure 13 the output characteristics of the structure B shown. In structure A, even when the distance dr exceeds 10 mm, the output voltage changes in the increasing direction. In contrast, in structure B, if the distance dr exceeds 8 mm, the output voltage no longer changes (becomes approximately constant).

[0088] That is, by comparing the output characteristics of structure A and structure B, it can be seen that: compared with the dashed-line structure B, in the solid-line structure A, the range of the distance dr for which the output change of the detection signal d can be obtained is larger, that is, the range that the displacement sensor 20 can detect is larger. In other words, compared with the dashed-line structure B, in the solid-line structure A, a higher linearity is obtained in the output characteristics.

[0089] Additionally, as another countermeasure for improving the linearity of the output characteristics, in the present embodiment, the outer shapes of the first part 521 and the second part 522 of the detected part 50 are not Figure 12 the square shown, but become rectangles extending along the length direction of the key 12.

[0090] Moreover, it is preferable that the regions acting as coils in the first part 521 and the second part 522 are large. Therefore, in the present embodiment, the outer shapes of the first part 521 and the second part 522 of the detected part 50 are each set as rectangles along the length direction of the key 12. Specifically, in the present embodiment, the outer dimension COL of each of the first part 521 and the second part 522 is greater than the outer dimension COW. Specifically, in the present embodiment, in each of the first part 521 and the second part 522, the ratio of the dimension between the outer dimension COW and the outer dimension COL is set to 7:10.

[0091] Next, the relationship between the distance L1 and the distance L2 is studied. Figure 15 is a graph showing the output characteristics when the ratio (%) of the distance L1 with respect to the distance L2 as a reference is changed to 100%, 120%, 140%, and 160%. In addition, for comparison, the voltage level δ on the vertical axis is normalized so that the minimum value is "0" and the maximum value is "1". The signal generation unit 60 for conducting this study uses Figure 8 the structure of.

[0092] Among the four output characteristics shown in the figure, the index representing linearity (e.g., R-squared value) is highest when the distance from L1 is 120% of L2 and lowest when the distance from L1 is 160% of L2. Therefore, from the perspective of ensuring linearity, the distance L1 is preferably a value within the range including the values before and after 120% with respect to the distance L2 as a reference. Specifically, the distance L1 is set to a value within the range greater than 100% and less than or equal to 140% with respect to the distance L2 (L2 < L1 ≤ 1.4 × L2).

[0093] As described above, if the distance L1 is set within the above range with respect to the distance L2, the magnetic field generated in the second coil 61 is moderately reduced and reaches the first coil 51, so that the linearity related to the output characteristics of the detection signal d can be improved. In addition, if the distance L1 is set within the above range with respect to the distance L2, compared with the case where it is set outside the above range, even if the first coil 51 is misaligned with respect to the second coil 61, the linearity of the output characteristics will not be impaired.

[0094] 1: Countermeasure 1 for improving the linearity of output characteristics

[0095] In addition to the above-described embodiments, as a countermeasure for improving the linearity of output characteristics, first, it is cited that a resistance element 64 is used as a damping resistor in the resonance circuit of the signal generation unit 60 to reduce the Q value (Quality Factor) of the resonance circuit.

[0096] Figure 16 It represents Figure 3 the figure of the output characteristics in the case where the resistance value of the resistance element 64 of the circuit changes step by step. In Figure 16 , the output characteristics are shown for each case where the resistance value of the resistance element 64 is changed to 6 values such as 0, 100, 200, 300, 400, and 500 Ω.

[0097] In Figure 16, in the state without the resistance element 64 (0 Ω), that is, in the state with the highest Q value, the following characteristics are obtained. That is, when the distance dr slightly exceeds 5 mm, the voltage level δ of the detection signal d is the largest, and thereafter, the voltage level δ decreases with the increase of the distance dr. Therefore, as the detection range, only a narrow range of about 1 to 5 mm can be used. However, in the state where the 100 Ω resistance element 64 is used in a manner of reducing the Q value, the following characteristics are obtained. That is, even in the range where the distance dr exceeds 5 mm, the voltage level δ of the detection signal d gradually increases with the increase of the distance dr. Moreover, as the resistance value of the resistance element 64 increases, in the small range of the distance dr (for example, 1 to 3 mm), the large range (for example, 8 to 10 mm), and the intermediate range between them (for example, 4 to 6 mm), the change amplitude of the voltage level δ gradually becomes smaller.

[0098] As described above, as the resistance value of the resistance element 64 of the signal generation unit 60 increases, the Q value decreases, and the linearity of the output characteristic becomes higher. That is, the detection distance can be increased.

[0099] In addition, in the detected unit 50, a resistance element serving as a damping resistor is not provided. This is because sufficient detection characteristics can be obtained even without reducing the Q value. However, for the stability of detection and the mass productivity of the device, a resistance element serving as a damping resistor can also be provided in the detected unit 50.

[0100] 2: Countermeasure 2 for improving the linearity of the output characteristic

[0101] In addition, as another countermeasure for improving the linearity of the output characteristic, an example is given where the frequency of the reference signal R supplied to the input terminal T1 is reduced by at most 2% compared to the resonance frequency of the detected unit 50 (that is, between 98% and 100% of this resonance frequency), and more preferably, it is about 1% lower than the resonance frequency of the detected unit 50.

[0102] Figure 17 is a graph showing the output characteristics in the case where the resonance frequency of the detected unit 50 (the reactance of the first coil 51 is 3.04 μH and the capacitance of the capacitor element 52 is 220 pF) is set to 6.15 MHz in the present embodiment and the frequency of the reference signal R is changed step by step. In Figure 17 it, the output characteristics are illustrated for each case where the frequency of the reference signal R is changed to 7 values of 6.00 MHz, 6.05 MHz, 6.10 MHz, 6.15 MHz, 6.20 MHz, 6.25 MHz, and 6.30 MHz. In Figure 17, when the frequency of the reference signal R is a frequency higher than 6.15 MHz (6.20 MHz, 6.25 MHz, 6.30 MHz), compared with the case when using a reference signal R with the same frequency as the resonance frequency of the detected part 50, the increasing slope of the output signal in the range where the distance dr is small (for example, 1 to 3 mm) and the intermediate range (for example, 4 to 6 mm) becomes larger, but the output characteristics cannot be maintained in the range greater than 7 mm. Further, when the frequency of the reference signal R is 6.25 MHz or 6.30 MHz, in the range where the distance dr is 6 mm or more, the voltage level δ decreases with the increase of the distance dr, which is not suitable for the detection purpose. On the other hand, if the frequency of the reference signal R is a frequency that is at most 2% lower than 6.15 MHz, linearity suitable for detection can be obtained. Further, if the frequency of the reference signal R is set to 6.10 MHz, which is about 1% lower than the resonance frequency of the detected part 50, the linearity of the output characteristics is higher.

[0103] In addition, in any of the cases of reducing the Q value of the resonance circuit of the signal generation unit 60 (countermeasure 1) and setting the frequency of the reference signal R lower than the resonance frequency of the detected part 50 (countermeasure 2), there is an optimal solution that maximizes the linearity. For this optimal solution, it can be obtained through computer-based numerical analysis.

[0104] In the embodiment, the outer shapes of the first part 521, the second part 522, the third part 621, and the fourth part 622 are set as rectangles including squares, but they can also be other quadrilaterals such as rhombuses, and can also be circles such as true circles and ellipses. In addition, regarding the center in the above cases, if it is a quadrilateral, it is the intersection of the diagonals, if it is a true circle, it is the center, and if it is an ellipse, it is the intersection of the major axis and the minor axis.

[0105] B: Modification examples

[0106] Hereinafter, specific modified modes added to the above-exemplified modes are illustrated. Two or more modes arbitrarily selected from the following illustrations can be appropriately combined within a non-contradictory range.

[0107] (1) In each of the above modes, a structure for detecting the displacement of the key 12 of the keyboard instrument 100 is illustrated. The movable part for detecting the displacement by the displacement sensor 20 is not limited to the key 12. In addition, the keyboard structure is not limited to the structure of the above example. Specific modes of movable parts different from the above example are illustrated below.

[0108] [Mode 1]

[0109] Figure 18Schematic diagram of the structure of applying the displacement sensor 20 to the striking mechanism 91 of the keyboard instrument 100. The striking mechanism 91 is an action mechanism that strikes a string (not shown) in conjunction with the displacement of each key 12 of the keyboard 10. Specifically, the striking mechanism 91 has, for each key 12, a hammer 911 that can strike the string by rotating, and a transmission mechanism 912 (for example, a wippen, a jack, a repetition lever, etc.) that rotates the hammer 911 in conjunction with the displacement of the key 12.

[0110] The detected part 50 is provided on the hammer 911 (for example, the hammer rod). In addition, the signal generating part 60 is provided on the supporting member 913. In the above structure, the displacement sensor 20 detects the displacement of the hammer 911. Specifically, the supporting member 913 is, for example, a structure that supports the striking mechanism 91. In addition, the detected part 50 may also be provided on a movable part other than the hammer 911 of the striking mechanism 91.

[0111] [Method 2]

[0112] Figure 19 1 is a schematic diagram showing a structure in which the displacement sensor 20 is applied to the pedal mechanism 92 of the keyboard instrument 100. The pedal mechanism 92 includes a pedal 921 operated by a user with a foot, a support member 922 supporting the pedal 921, and an elastic body 923 urging the pedal 921 upward in the vertical direction.

[0113] The detected portion 50 is provided on the bottom surface of the pedal 921. In addition, the signal generating portion 60 is provided on the supporting member 922 so as to face the detected portion 50. In the above-described structure, the displacement sensor 20 detects the displacement of the pedal 921.

[0114] In addition, the musical instrument using the pedal mechanism 92 is not limited to the keyboard instrument 100. For example, the pedal mechanism 92 having the same structure can be used for any musical instrument such as a percussion instrument.

[0115] As can be understood from the above examples, the object detected by the displacement sensor is generally represented as a movable part that is displaced in accordance with the performance action. In addition to the performance operating parts such as the key 12 or the pedal 921 directly operated by the user, the movable part includes a structure such as the hammer 911 that is displaced in conjunction with the operation of the performance operating part. However, the movable part of the present invention is not limited to the part that is displaced in accordance with the performance action. That is, the movable part is generally represented as a part that can be displaced, regardless of the opportunity for displacement.

[0116] (2) In each of the above-described modes, a configuration in which the keyboard instrument 100 has a sound source circuit 34 is illustrated. However, in a configuration in which the keyboard instrument 100 has a sound generation mechanism such as a hammers mechanism 91, etc., the sound source circuit 34 can also be omitted. The detection system 15 is used to record the performance content of the keyboard instrument 100. The sound generation mechanism and the sound source circuit 34 are collectively referred to as a sound generation unit that generates sound corresponding to the result of detection by the detection system 15.

[0117] As understood from the above description, the present invention is also determined to be a device (performance operation device) that controls musical sounds by outputting an operation signal corresponding to a performance action to the sound source circuit 34 or the sound generation mechanism. As illustrated in each of the above-described modes, in addition to an instrument (keyboard instrument 100) having a sound source circuit 34 or a sound generation mechanism, devices that do not have a sound source circuit 34 or a sound generation mechanism (e.g., a MIDI controller or the aforementioned pedal mechanism 92) are also included in the concept of the performance operation device (instrument playing apparatus). That is, the performance operation device of the present invention is collectively referred to as a device that a performer (operator) operates for performance.

[0118] (3) The above countermeasures for improving the linearity of the output characteristics can be implemented singly, or two or more countermeasures can be appropriately combined.

[0119] C: Appendix

[0120] According to the modes illustrated above, for example, the following configuration can be grasped.

[0121] The displacement sensor according to the mode (the first mode) of the present invention has: a detected portion provided on a movable member that is displaced corresponding to an operation, including a first coil; and a signal generation portion including a second coil opposed to the first coil, generating a detection signal corresponding to the relative position between the first coil and the second coil, and the outer dimension of the first coil in a first direction and the outer dimension of the first coil in a second direction orthogonal to the first direction are different when viewed from above.

[0122] According to this mode, when the detection signal changes corresponding to the change in the relative position between the first coil of the detected portion and the opposed second coil, the linearity is improved, so that a detection signal that accurately reflects the displacement of the movable member can be generated. Therefore, the ranging distance can be extended.

[0123] The "outer dimension" of a coil in a specific direction refers to the dimension (size) in the corresponding direction related to the contour line indicating the outer shape of the coil, and can also be referred to as the maximum value of the size of the coil in the corresponding direction.

[0124] In an example of the first mode (second mode), the detected portion includes a rectangular substrate formed with the first coil, the first direction is the long side direction of the substrate, the second direction is the short side direction of the substrate, and the outer dimension of the first coil in the second direction is less than or equal to the dimension of the substrate in the short side direction.

[0125] In another mode of the present invention (third mode), the outer dimension of the first coil in the first direction is greater than the outer dimension of the first coil in the second direction.

[0126] In addition, a displacement sensor according to another mode of the present invention (fourth mode) includes: a detected portion provided on a movable member that is displaced corresponding to an operation and includes a first coil; and a signal generation portion that includes a second coil opposed to the first coil and generates a detection signal corresponding to the relative position between the first coil and the second coil. The first coil has a first portion and a second portion that generate magnetic fields in opposite directions by supplying current to the first coil, and the second coil has a third portion and a fourth portion that generate magnetic fields in opposite directions by supplying current to the second coil. A first distance between the center of the first portion and the center of the second portion is greater than a second distance between the center of the third portion and the center of the fourth portion.

[0127] According to this mode, the linearity when the detection signal changes corresponding to the change in the relative position between the first coil of the detected portion and the opposed second coil is improved, so that a detection signal that accurately reflects the displacement of the movable member can be generated. In addition, the leakage of the magnetic field generated by the second coil is reduced, so that the detection accuracy can be improved.

[0128] In an example of the fourth mode (fifth mode), the first distance is greater than 100% of the second distance and less than or equal to 140% of the second distance.

[0129] An electronic musical instrument according to one mode of the present invention (sixth mode) includes: a displacement sensor according to any of the above-exemplified modes; and a sound control portion that generates an audio signal representing a sound corresponding to the level of the detection signal.

[0130] Another aspect (the seventh aspect) of the present invention relates to a displacement sensor having: a detected portion provided on a movable member that is displaced in response to an operation, including a substrate formed with a first coil; and a signal generation portion including a second coil that generates a detection signal corresponding to a relative position between the first coil of the detected portion and the second coil, the second coil being opposed to the first coil, wherein both the detected portion and the signal generation portion are formed of a resonant circuit, the signal generation portion has a resistance element that reduces the Q value, and the detected portion does not have a resistance element that reduces the Q value.

[0131] Another aspect (the eighth aspect) of the present invention relates to a displacement sensor having: a detected portion provided on a movable member that is displaced in response to an operation, including a substrate formed with a first coil; and a signal generation portion including a second coil that generates a detection signal corresponding to a relative position between the first coil of the detected portion and the second coil, the second coil being opposed to the first coil, wherein the frequency of the detection signal of the signal generation portion differs from the resonant frequency of the detected portion by at most 2% (i.e., between 98% and 100% of the resonant frequency).

[0132] 100…Keyboard musical instrument (electronic musical instrument), 10…Keyboard, 12…Keys, 15…Detection system, 20…Displacement sensor, 21…Signal processing circuit, 22…Supply circuit, 23…Output circuit, 30…Information processing device, 31…Control device, 32…Storage device, 33…A / D converter, 34…Sound source circuit, 40…Sound playback device, 50…Detected portion, 51…First coil, 52…Capacitor element, 521…First part, 522…Second part, 551…Substrate, 523…Third part, 524…Fourth part, 551, 552, 553…Substrates, 60…Signal generation portion, 61…Second coil, 612…Wiring pattern, 621…Third part, 622…Fourth part, 651…Substrate, 62…Capacitor element, 63…Capacitor element, 64…Resistance element, 911…Hammer, 912…Transfer mechanism, 913…Support member, 921…Pedal, 922…Support member, 923…Elastomer.

Claims

1. A displacement sensor having: A first resonance circuit provided in a movable member that moves in correspondence with an operation, including a first coil; and A second resonance circuit including a second coil opposed to the first coil, A detection signal corresponding to the relative position between the first coil and the second coil is generated by supplying a reference signal to the second resonance circuit. In this displacement sensor, The frequency of the reference signal is in a range of 98% or more of the resonance frequency of the first resonance circuit and less than the resonance frequency.

2. The displacement sensor according to claim 1, wherein The frequency of the reference signal is 99% of the resonance frequency of the first resonance circuit.

3. The displacement sensor according to claim 1 or 2, wherein The second resonance circuit includes a damping resistor that reduces the Q value of the second resonance circuit.

4. The displacement sensor according to any one of claims 1 to 3, wherein The first coil has a first portion and a second portion that generate magnetic fields in opposite directions with respect to each other by supplying current to the first coil, The first portion and the second portion are arranged in a first direction, In each of the first portion and the second portion, the outer dimension in the first direction is larger than the outer dimension in a second direction orthogonal to the first direction.

5. An electronic musical instrument having: The displacement sensor according to any one of claims 1 to 4; and A sound control unit that generates an audio signal representing a sound corresponding to the level of the detection signal.

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