Displacement sensor and electric musical instrument

Abstract

To generate a detection signal on which displacement of a movable member is reflected with high precision.SOLUTION: A displacement sensor 20 comprises a detected part 50 which is installed at a movable member, and includes a first coil 51, and a signal generation part 60 which includes a second coil 61, and generates a detection signal d corresponding to relative position between the first coil 51 and second coil 61. The first coil 51 includes a first part and a second part where magnetic fields in mutually opposite directions are generated as a current supplied to the first coil 51, and a second coil 61 includes a third part and a fourth part where magnetic fields in mutually opposite directions are generated as a current is supplied to the second coil, wherein a part of the first part on the opposite side from the second part protrudes from an edge of the third part on the opposite side from the fourth part, and a part of the second part on the opposite side from the first part protrudes from an edge of the fourth part on the opposite side from the third part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a displacement sensor and an electronic musical instrument. [Background technology]

[0002] For example, various techniques have been proposed for detecting the displacement of a movable member such as a key in a keyboard instrument. Patent Document 1 discloses a configuration for detecting the position of each key by using a coil installed on the frame of the keyboard instrument and a metal plate installed on each key. In this configuration, when the metal plate is displaced by pressing a key, the current flowing through the coil changes. By detecting the current flowing through the coil, a detection signal reflecting the displacement of the key is generated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-48295 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it is difficult to generate a detection signal that reflects the displacement of the movable member with high accuracy in the technology of Patent Document 1. In consideration of such circumstances, an object of one aspect of the present disclosure is to generate a detection signal that reflects the displacement of the movable member with high accuracy. [Means for solving the problem]

[0005] In order to achieve the above object, a displacement sensor according to one embodiment of the present disclosure is installed on a movable member that is displaced in response to an operation, and comprises a detectable portion including a first coil, and a signal generating portion including a second coil facing the first coil and generating a detection signal according to the relative positions of the first coil and the second coil, wherein the first coil includes a first portion and a second portion located in a first direction of the first portion, and a magnetic field in an opposite direction to each other is generated in the first portion and the second portion by supplying a current to the first coil, the second coil includes a third portion facing the first portion and a fourth portion facing the second portion, and a magnetic field in an opposite direction to each other is generated in the third portion and the fourth portion by supplying a current to the second coil, and a portion of the first portion located in a second direction opposite to the first direction protrudes in the second direction from an edge of the third portion located in the second direction, and a portion of the second portion located in the first direction protrudes in the first direction from an edge of the fourth portion located in the first direction.

[0006] An electronic musical instrument according to one aspect of the present disclosure includes a displacement sensor according to the present disclosure and a sound control unit that generates an audio signal in response to the detection signal. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing an example of the configuration of a keyboard instrument to which a displacement sensor according to one embodiment is applied; [Diagram 2] FIG. 1 is a block diagram showing an example of the configuration of a keyboard instrument. [Diagram 3] FIG. 2 is a diagram showing a circuit of a main part of a displacement sensor. [Figure 4] FIG. 2 is a block diagram illustrating an example of a signal processing circuit. [Diagram 5] FIG. 4 is a plan view showing a specific configuration of a detection target portion. [Figure 6] 6 is a cross-sectional view taken along line Aa in FIG. 5. [Figure 7] 4 is an explanatory diagram of a magnetic field generated by a first coil of a detected part, etc. FIG. [Figure 8]4 is a plan view illustrating a specific configuration of a signal generating unit. FIG. [Figure 9] 9 is a cross-sectional view taken along line Bb in FIG. 8. [Figure 10] 4 is an explanatory diagram of a magnetic field generated by a second coil of the signal generating unit. FIG. [Figure 11] 4 is a diagram illustrating an example of the positional relationship between a first coil and a second coil. FIG. [Figure 12] FIG. 11 is a plan view showing a configuration of a detection target portion according to a comparative example. [Figure 13] FIG. 11 is a plan view showing a configuration of a detection target portion according to a comparative example. [Figure 14] FIG. 4 is a diagram illustrating an example of an output characteristic of a detection signal. [Figure 15] FIG. 4 is a diagram illustrating an example of an output characteristic of a detection signal. [Figure 16] FIG. 4 is a diagram illustrating an example of an output characteristic of a detection signal. [Figure 17] FIG. 4 is a diagram illustrating an example of an output characteristic of a detection signal. [Figure 18] FIG. 13 is a diagram in which a displacement sensor according to a modified example is applied. [Figure 19] FIG. 13 is a diagram in which a displacement sensor according to a modified example is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A: Embodiment FIG. 1 is a block diagram illustrating a configuration of a keyboard instrument 100 to which a displacement sensor according to one embodiment of the present disclosure is applied. The keyboard instrument 100 is an electronic musical instrument equipped with a keyboard 10, a detection system 15, an information processing device 30, and a sound emitting 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 in response to a performance action by a user. The detection system 15 detects the displacement (position) of the key 12. The information processing device 30 generates an audio signal V in response to the result of detection by the detection system 15. The audio signal V is a signal representing a musical tone of a pitch corresponding to the key 12 operated by the user. The sound emitting device 40 emits the sound represented by the audio signal V. For example, a speaker or a headphone is used as the sound emitting device 40.

[0009] 2 is a block diagram illustrating a specific configuration of a keyboard instrument 100, focusing on one key 12 of 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. An end 121 of each key 12 is displaced in the vertical direction when the user presses and releases the key. The detection system 15 generates a detection signal D of a level corresponding to a position Z of the end 121 in the vertical direction for each of the multiple keys 12. The position Z is expressed, for example, by the amount of displacement of the end 121 based on the position of the end 121 in a released state in which no load is applied to the key 12.

[0010] The detection system 15 includes a displacement sensor 20 provided for each key 12 and a signal processing circuit 21 common to each key 12. The displacement sensor 20 is a position sensor that detects the position of each key 12, and includes a detected part 50 and a signal generating part 60. The signal generating part 60 is mounted on the support member 14. The detected part 50 is mounted on the key 12. Specifically, the detected part 50 is mounted on the bottom surface (hereinafter referred to as the "mounting surface") 122 of the key 12. The detected part 50 includes a first coil 51. The signal generating part 60 includes a second coil 61. The first coil 51 and the second coil 61 face each other with a gap between them in the vertical direction. The distance between the signal generating part 60 and the detected part 50 (the distance between the first coil 51 and the second coil 61) changes in response to a change in the position Z of the end part 121 of the key 12 due to pressing or releasing the key. The signal processing circuit 21 generates a detection signal D having a level according to the distance between the first coil 51 and the second coil 61.

[0011] 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 realized as a computer system including a control device 31, a storage device 32, an A / D converter 33, and a sound source circuit 34.

[0012] The A / D converter 33 converts the detection signal D supplied from the signal processing circuit 21 from analog to digital. 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 types of 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).

[0013] 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. The control device 31 also instructs the sound source circuit 34 to generate a musical tone corresponding to the position Z of each key 12. The sound source circuit 34 generates an audio signal V representing the musical tone instructed by the control device 31. That is, the sound source circuit 34 detects that the key has reached a predetermined position according to the voltage level δ of the detection signal D and starts generating the audio signal V. Then, for example, the volume of the audio signal V is controlled according to the speed change of the voltage level δ. The audio signal V is supplied from the sound source circuit 34 to the sound emitting device 40, and the musical tone corresponding to the playing action of the user is emitted from the sound emitting device 40. Specifically, the musical tone is emitted when the user presses each key 12, and the musical tone is stopped when the user releases the key 12.

[0014] The storage device 32 is a single or multiple memories that store the program executed by the control device 31 and the data used by the control device 31. The storage device 32 is configured with a known storage medium such as a magnetic storage medium or a semiconductor storage medium. The storage device 32 may be configured with a combination of multiple types of storage media. A portable storage medium that can be attached to and detached from the keyboard instrument 100, or an external storage medium (e.g., online storage) with which the keyboard instrument 100 can communicate may be used as the storage device 32. The control device 31 may realize the function of the sound source circuit 34 by executing a 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 an audio signal V according to the voltage level δ of the detection signal D.

[0015] FIG. 3 is a circuit diagram illustrating an example of an electrical configuration of the detection target section 50 and the signal generating section 60 that constitute the displacement sensor 20. As shown in FIG. The signal generating unit 60 includes an input terminal T1, an output terminal T2, a second coil 61, a capacitance element 62, a capacitance element 63, and a resistance element 64. In the signal generating unit 60, a resonant circuit is formed by the second coil 61, the capacitance element 62, the capacitance element 63, and the resistance element 64. The input terminal T1 is connected to one end of the resistance element 64, and the other end of the resistance element 64 is connected to one end of the capacitance 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 capacitance element 63. The other end of the capacitance element 62 and the other end of the capacitance element 63 are grounded to a potential Gnd that is a reference for zero voltage.

[0016] 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 generating portion 60 is set, for example, according to the relationship with the resonant frequency of the detected portion 50. The resonant frequency of the signal generating portion 60 is set, for example, to a frequency approximately equal to 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.

[0017] A reference signal R is supplied to the input terminal T1 of the signal generating unit 60. The reference signal R is a voltage signal whose level fluctuates periodically. For example, a periodic signal of any waveform, such as a sine wave, is used as the reference signal R. The frequency of the reference signal R is set according to its relationship with the resonant frequency of the detected unit 50, etc. For example, the frequency of the reference signal R is approximately equal to the resonant frequency of the signal generating unit 60 and the detected unit 50.

[0018] A current corresponding to the reference signal R is supplied to the second coil 61, whereby a magnetic field is generated in the second coil 61. An induced current is generated in the first coil 51 due to 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 offsets the change in the magnetic field of the second coil 61. The magnetic field generated in the first coil 51 changes according 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 generating unit 60. The detection signal d is a periodic signal whose level changes with the same period as the reference signal R.

[0019] 4 is a block diagram illustrating a 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 a reference signal R to each of the input terminals T1 of the multiple signal generating units 60. The supply circuit 22 supplies the reference signal R to each signal generating unit 60 in a time-division manner. Specifically, the supply circuit 22 is a demultiplexer that sequentially selects each of the multiple signal generating units 60 and supplies the reference signal R to the selected signal generating unit 60. That is, the reference signal R is supplied to each of the multiple signal generating units 60 in a time-division manner. 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 generating unit 60.

[0020] The output circuit 23 generates a detection signal D by arranging the detection signals d output sequentially from each of the multiple signal generating units 60 on a time axis. That is, the detection signal D is a signal that indicates, in a time-division manner, a signal of a voltage level δ corresponding to the distance dr between the first coil 51 and the second coil 61 of each key 12. As described above, the distance dr between the first coil 51 and the second coil 61 correlates with the position Z of each key 12, so the detection signal D is a signal corresponding to the position Z of each of the multiple keys 12. That is, for one key 12, the detection signal d is expressed as a signal corresponding to the relative position between the first coil 51 and the second coil 61 facing the first coil 51. The detection signal D generated by the output circuit 23 is supplied to the information processing device 30.

[0021] Next, the configurations of the detection target section 50 and the signal generating section 60 will be described. Fig. 5 is a plan view showing a specific configuration of the detected portion 50, as viewed from the side of the signal generating portion 60. Fig. 6 is a cross-sectional view taken along line Aa in Fig. 5.

[0022] The detected part 50 includes a substrate 551 and a wiring pattern provided on a surface F1 and a surface F2 of the substrate 551. The substrate 551 is, for example, a rectangular plate-like member having insulating properties. The surface F1 of the detected part 50 is a surface that is attached to the installation surface 122 of the key 12. The wiring pattern of the detected part 50 is formed by patterning a conductive layer such as a copper foil provided on the surfaces F1 and F2 of the substrate 551. 5, the vertical direction is the direction in which the keys 12 are arranged, and the horizontal direction is the longitudinal direction of each key 12. The width Bw of the detection target part 50 attached to the installation surface 122 of the key 12 is equal to or smaller than the width Kw of each key 12.

[0023] Moreover, the surface F2 is the surface opposite to the surface F1. Therefore, the surface F2 faces the signal generating unit 60. The first coil 51 of the detected unit 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 a 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 winding direction as the first portion 521. The spiral center of the first portion 521 is the via C1, and the spiral center of the second portion 522 is the via C2. The vias C1 and C2 are electrically connected by the wiring pattern 515 on the front surface F1.

[0024] In this embodiment, in the spiral of the first portion 521, a straight line extending from the via C1 is bent at approximately 90 degrees and spreads outward. The outer shape of the first portion 521 is rectangular. Similarly, in the spiral of the second portion 522, a straight line extending from the via C2 is bent at approximately 90 degrees and spreads outward. The outer shape of the second portion 522 is rectangular. The first portion 521 and the second portion 522 have a rectangular outer shape. In FIG. 5, 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 illustrated for each of the first portion 521 and the second portion 522. The outer dimension COW corresponds to the dimension (size) of the first coil 51 in the short side direction of the substrate 551. The outer dimension COW of each of the first portion 521 and the second portion 522 is equal to or smaller than the dimension Bw of the substrate 551 in the short side direction. The long side direction of the substrate 551 coincides with the arrangement direction of the first portion 521 and the second portion 522, i.e., the longitudinal direction of the key 12. The short side direction of the substrate 551 coincides with the direction perpendicular to the arrangement direction of the first portion 521 and the second portion 522, i.e., the width direction of the key 12.

[0025] The via C1 is located at the center of the first portion 521. This center is the point where the diagonals of the rectangular outline of the first portion 521 intersect. Similarly, the via C2 is located at the center of the second portion 522. This center is the point where the diagonals of the rectangular outline of the second portion 522 intersect. Moreover, the distance between the center (via C1) of the first portion 521 and the center (via C2) of the second portion 522 is denoted as L1. Note that the distance L1 is an example of the first distance.

[0026] A capacitive element 52 is mounted between one end of the first portion 521 when the via C1 of the first portion 521 is defined as one end, and the other end of the second portion 522 when the via C2 of the second portion 522 is defined as one end. Therefore, the equivalent circuit of the detected portion 50 has a configuration in which the capacitive element 52 is connected to both ends of the first coil 51 as shown in FIG. In this embodiment, the first portion 521 and the second portion 522 have the same dimensions and shape, but this is not limited thereto. For example, the first portion 521 and the second portion 522 may have different shapes or dimensions. The planar shape of one or both of the first portion 521 and the second portion 522 may be a rectangle in which the vertical direction in FIG. 5 is the long side direction and the horizontal direction in FIG. 5 is the short side direction. The planar shape of the first coil 51 is not limited to a shape including the first portion 521 and the second portion 522. In other words, the first coil 51 may be formed of one winding portion.

[0027] Fig. 8 is a plan view showing a specific configuration of the signal generating section 60, as viewed from the side of the detected section 50. Fig. 9 is a cross-sectional view taken along line Bb in Fig. 8.

[0028] The signal generating unit 60 includes a substrate 651 and a wiring pattern provided on surfaces F3 and F4 of the substrate 651. The substrate 651 is an insulating plate-like member. The surface F4 of the signal generating unit 60 faces the support member 14. The surface F3 is the surface opposite to the surface F4, and faces the detected unit 50. The wiring pattern is formed by patterning a conductive layer such as copper foil provided on the surfaces F3 and F4 of the substrate 651.

[0029] The up-down direction in Fig. 8 is the direction in which multiple keys 12 (not shown in Fig. 8) are arranged. The left-right direction in Fig. 8 is the longitudinal direction of each key 12. The longitudinal direction of a key 12 is the direction from the tip side (player side) of the key 12 to the base side of the key 12.

[0030] The second coil 61 of the signal generating unit 60 is composed of a third portion 621 and a fourth portion 622. The third portion 621 and the fourth portion 622 are part of a wiring pattern formed on the surface F3. The third portion 621 is a portion formed in a substantially square spiral shape. The fourth portion 622 is a portion formed in substantially the same shape as the third portion 621. That is, the fourth portion 622 is formed in a spiral shape in the same winding direction as the third portion 621. The spiral center of the third portion 621 is the via C11, and the spiral center of the fourth portion 622 is the via C12. The vias C11 and C12 are electrically connected by the wiring pattern 612 on the surface F4. In this embodiment, the third portion 621 and the fourth portion 622 have the same dimensions and the same shape, but this is not limited to this. For example, the dimensions of the third portion 621 and the fourth portion 622 may be different. Furthermore, the third portion 621 and the fourth portion 622 may have different shapes. Furthermore, the planar shape of the second coil 61 is not limited to a shape including the third portion 621 and the fourth portion 622. In other words, the second coil 61 may be formed of one winding portion.

[0031] In this embodiment, the external shape of the third portion 621 is approximately square. Similarly, the external shape of the fourth portion 622 is approximately square. The direction of one side of the square that is the external shape of third portion 621 and fourth portion 622 coincides with the longitudinal direction of key 12, and the direction perpendicular to the side coincides with the width direction of key 12. The dimension of one side of the square (external dimension) is defined as B2.

[0032] The via C11 is located at the center of the third portion 621, and the via C12 is located at the center of the fourth portion 622. The center here refers to the center of the coil in a plan view, which is the point where the diagonals intersect if the coil is a square or rectangle, and the center of the outer circle if the coil is a circle. Moreover, the distance between the center of the third portion 621 (the via C11 in this embodiment) and the center of the fourth portion 622 (the via C12 in this embodiment) is defined as L2. Note that the distance L2 is an example of the second distance.

[0033] Of the wiring pattern on the front surface F3, the portion other than the second coil 61 is wiring for connecting the capacitive element 62, the capacitive element 63, the resistive 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 a detection signal d with a 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. In the above-described configuration of the detected portion 50 and the signal generating portion 60, the first portion 521 faces the third portion 621, and the second portion 522 faces the fourth portion 622. In addition, as an example, the dimensional relationship is COW=B2×70% and COL=B2.

[0034] Next, a description will be given of the operation of the circuits in the detected portion 50 and the signal generating portion 60. Fig. 7 is a diagram showing an example of the direction of a magnetic field generated by the detected portion 50. Fig. 10 is a diagram showing an example of the direction of a magnetic field generated by the signal generating portion 60. 8, when a counterclockwise current flows from the via C11 in the third portion 621, a clockwise current flows toward the via C12 in the fourth portion 622. Therefore, a magnetic field is generated in the third portion 621 toward the front of the page in FIG. 8 and upward in FIG. 10, and a magnetic field is generated in the fourth portion 622 toward the back of the page in FIG. 8 and downward in FIG. 10.

[0035] That is, as illustrated in Fig. 10, magnetic fields in opposite directions are generated in the third portion 621 and the fourth portion 622. As described above, the multiple keys 12 on the keyboard 10 are arranged in a direction perpendicular to the plane of the paper in Fig. 10. Therefore, by generating magnetic fields in opposite directions in the third portion 621 and the fourth portion 622, diffusion of the magnetic fields generated in the signal generating units 60 facing each of the adjacent keys 12 is reduced. As a result of the reduction in diffusion of the magnetic field, a detection signal D that reflects the position Z of each of the multiple keys 12 with high accuracy is generated.

[0036] 8, a case is illustrated in which a counterclockwise current flows through the third portion 621 and a clockwise current flows through the fourth portion 622. Similarly, when a clockwise current flows through the third portion 621 and a counterclockwise current flows through the fourth portion 622, the directions of the magnetic fields are reversed.

[0037] The third portion 621 and the fourth portion 622 of the second coil 61 in the signal generating unit 60 are formed by patterning the conductive layer on the surface F4. This has the advantage that the second coil 61 is easier to manufacture and handle than, for example, a configuration in which the second coil 61 is formed by winding a conductive wire.

[0038] In this manner, when the first coil 51 moves in a direction away from the second coil 61 while the reference signal R is supplied to the signal generating unit 60, a magnetic field is generated in the first coil 51 in a direction that prevents the magnetic field generated by the second coil 61 from decreasing (i.e., 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 induced in the first coil 51. For example, when a magnetic field in the direction shown in Figure 10 is generated by the second coil 61 of the signal generating unit 60 and the first coil 51 of the detected unit 50 moves in a direction away from the second coil 61, a magnetic field in the same direction as the magnetic field generated by the second coil 61 is generated in the first coil 51. Therefore, in FIG. 5, a current flows in a clockwise direction through the first portion 521 of the first coil 51, and a current flows in a counterclockwise direction through the second portion 522. Furthermore, when a magnetic field in the direction shown in Figure 10 is generated by the second coil 61 of the signal generating unit 60 and the first coil 51 of the detected unit 50 moves in a direction approaching the second coil 61, a magnetic field in the opposite direction to the magnetic field generated by the second coil 61 is generated in the first coil 51. 5, a current flows counterclockwise through the first portion 521 of the first coil 51, and a current flows clockwise through the second portion 522. In FIG.

[0039] In addition, when a magnetic field in a direction opposite to the direction illustrated in Figure 10 is generated in the second coil 61 and the first coil 51 approaches the second coil 61, a magnetic field in the opposite direction to the magnetic field generated by the second coil 61, i.e., a magnetic field as shown in Figure 7, is generated in the first coil 51. Furthermore, when a magnetic field in the direction shown in Figure 10 is generated by the second coil 61 and the first coil 51 approaches the second coil 61, and when a magnetic field in the direction opposite to the direction shown in Figure 10 is generated in the second coil 61 and the first coil 51 moves away from the second coil 61, a current flows clockwise in the first part 521 of the first coil 51 and a current flows counterclockwise in the second part 522.

[0040] Next, a configuration and process for improving the linearity of the output characteristics of the detection signal, that is, for lengthening the detection distance in the detection system 15, will be described. The output characteristics are the relationship between the distance dr between the first coil 51 and the second coil 61 and the voltage level δ of the detection signal d. The linearity of the output characteristics means that the relationship of the voltage level δ to the distance dr is close to a proportional relationship. Furthermore, the detection distance means the width of the range of the distance dr (detection range) in which the voltage level δ changes significantly with respect to the change in the distance dr. In other words, the detection distance means the range of the distance dr reflected in the voltage level δ.

[0041] In order to improve the linearity of the output characteristics, in this embodiment, the distance L1 (first distance) between the center of the first portion 521 and the center of the second portion 522 is greater than the distance L2 (second distance) between the center of the third portion 621 and the center of the fourth portion 622.

[0042] Fig. 11 is a plan view showing the positional relationship between the first coil 51 and the second coil 61 in a state in which the detected part 50 is attached to the installation surface 122 of the key 12 and the signal generating part 60 is installed on the support member 14. In detail, Fig. 11 is a plan view showing 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 as seen through from the detected part 50 towards the signal generating part 60 in the above state.

[0043] The vias C1, C2, C11, and C12 are located on a straight line Ln along the longitudinal direction of the key 12. Furthermore, the vias C11 and C12 are located between the vias C1 and C2.

[0044] In the displacement sensor 20 according to this embodiment, the distance L1 between the center of the first portion 521 and the center of the second portion 522 in the detection section 50 is greater than the distance L2 between the center of the third portion 621 and the center of the fourth portion 622 in the signal generation section 60. First, the effectiveness of the configuration in which the distance L1 is greater than the distance L2 will be described.

[0045] The output characteristics are compared between configurations A and B, which have different lengths of distance L1 and distance L2. Configuration A is a configuration in which distance L1 in first coil 51 exceeds distance L2, as shown in Fig. 12. Configuration B is a configuration in which distance L1 in first coil 51 is shorter than distance L2, as shown in Fig. 13. Specifically, the distance L1 in Fig. 12 is L2 x 120% shown in Fig. 8, and the distance L1 in Fig. 13 is L2 x 80%. The external dimensions COL and COW in Fig. 12 and the external dimensions COL and COW in Fig. 13 are the length of the external dimension B2 x 70% shown in Fig. 8. The signal generating section 60 in this comparison uses the configuration in Fig. 8.

[0046] Fig. 14 is a diagram showing the output characteristics of the displacement sensor 20 in configurations A and B. In Fig. 14, the vertical axis is the voltage level δ [V] of the detection signal d, and the horizontal axis is the distance according to the position of the displacement Z, specifically, the distance dr between the first coil 51 and the second coil 61. In Fig. 14, the solid line indicates the output characteristic of configuration A shown in Fig. 12, and the dashed line indicates the output characteristic of configuration B shown in Fig. 13. In configuration A, the output voltage changes in an increasing direction even when the distance dr exceeds 10 mm, whereas in configuration B, the output voltage stops changing (becomes an almost constant value) when the distance dr exceeds 8 mm.

[0047] That is, when comparing the output characteristics of configurations A and B, it can be seen that configuration A (solid line) has a wider range of distance dr at which an output change in detection signal d can be obtained, i.e., the range detectable by the displacement sensor 20 is wider, than configuration B (dashed line). In other words, configuration A (solid line) has a higher linearity in the output characteristics than configuration B (dashed line).

[0048] Also, as another measure for improving the linearity of the output characteristics, in the present embodiment, the outer shapes of the first portion 521 and the second portion 522 in the detected portion 50 are not squares shown in FIG. 12, but rectangles extending in the longitudinal direction of the key 12.

[0049] And it is preferable that the areas functioning as coils in the first portion 521 and the second portion 522 are large. For this reason, in the present embodiment, the outer shapes of the first portion 521 and the second portion 522 in the detected portion 50 are each rectangles along the longitudinal direction of the key 12. Specifically, in the present embodiment, the outer dimension COL of each of the first portion 521 and the second portion 522 exceeds the outer dimension COW. Specifically, in the present embodiment, in each of the first portion 521 and the second portion 522, the dimensional ratio of the outer dimension COW to the outer dimension COL is 7:10.

[0050] Next, the relationship between the distance L1 and the distance L2 will be examined. FIG. 15 is a diagram showing output characteristics when the ratio (%) of the distance L1 based on the distance L2 is changed to 100%, 120%, 140%, and 160%. The voltage level δ on the vertical axis is normalized so that the minimum value is "0" and the maximum value is "1" for comparison. The signal generation unit 60 in this examination uses the configuration of FIG. 8.

[0051] Among the four output characteristics shown in this figure, the index indicating linearity (for example, the R squared value) is the highest when the distance L1 is 120% of L2, and the lowest when the distance L1 is 160% of L2. Therefore, from the viewpoint of ensuring linearity, the distance L1 is preferably a numerical value within a range including values around 120% based on the distance L2. Specifically, the distance L1 is set to a numerical value within a range greater than 100% and equal to or less than 140% with respect to the distance L2 (L2 < L1 ≤ 1.4 × L2).

[0052] When distance L1 is set to be within the above range relative to distance L2 in this manner, the magnetic field generated in the second coil 61 is appropriately reduced before reaching the first coil 51, thereby improving the linearity of the output characteristics of the detection signal d. Furthermore, when distance L1 is set to be within the above range relative to distance L2, even if the first coil 51 is misaligned relative to the second coil 61, the linearity of the output characteristics is not impaired compared to when distance L1 is set outside the above range.

[0053] 1: Method 1 for improving the linearity of the output characteristics In addition to the above-described embodiments, a first measure for improving the linearity of the output characteristics is to use a resistive element 64 as a damping resistor in the resonant circuit in the signal generating unit 60 to lower the Q value (Quality Factor) of the resonant circuit. Fig. 16 is a diagram showing output characteristics when the resistance value of the resistive element 64 in the circuit of Fig. 3 is changed in stages. In Fig. 16, output characteristics are shown for each of six cases in which the resistance value of the resistive element 64 is changed to 0, 100, 200, 300, 400, and 500 Ω.

[0054] In FIG. 16, in the absence of the resistive element 64 (0Ω), i.e., in the state where the Q value is the highest, the voltage level δ of the detection signal d becomes maximum when the distance dr slightly exceeds 5 mm, and the voltage level δ decreases with increasing distance dr thereafter. Therefore, only a narrow range of about 1 to 5 mm can be used as the detection range. However, in the state where the resistive element 64 of 100Ω is used to lower the Q value, the voltage level δ of the detection signal d increases slightly with increasing distance dr even in the range where the distance dr exceeds 5 mm. Then, as the resistance value of the resistive element 64 increases, the change width of the voltage level δ becomes smaller in each of the ranges where the distance dr is small (e.g., 1 to 3 mm), large (e.g., 8 to 10 mm), and the intermediate range between them (e.g., 4 to 6 mm).

[0055] In this way, as the resistance value of the resistive element 64 in the signal generating section 60 increases, the Q value decreases and the linearity of the output characteristics increases. That is, the detection distance can be increased. It should be noted that no resistive element serving as a damping resistor is provided in the detected portion 50. This is because sufficient detection characteristics can be obtained without lowering the Q value. However, for the sake of detection stability and mass productivity of the device, a resistive element serving as a damping resistor may be provided in the detected portion 50.

[0056] 2: Method 2 for improving the linearity of the output characteristics Another measure for improving the linearity of the output characteristics is to lower the frequency of the reference signal R supplied to the input terminal T1 by up to 2% lower than the resonant frequency of the detected part 50 (i.e., between 98% and 100% of the resonant frequency), and more preferably, to about 1% lower than the resonant frequency of the detected part 50.

[0057] FIG. 17 is a diagram showing output characteristics in the present embodiment when the resonant frequency of the detected portion 50 (the reactance of the first coil 51 is 3.04 μH, and the capacitance of the capacitive element 52 is 220 pF) is set to 6.15 MHz, and the frequency of the reference signal R is changed stepwise. In FIG. 17, output characteristics are shown for each of the seven cases in which the frequency of the reference signal R is changed to 6.00 MHz, 6.05 MHz, 6.10 MHz, 6.15 MHz, 6.20 MHz, 6.25 MHz, and 6.30 MHz. In FIG. 17, when the frequency of the reference signal R is higher than 6.15 MHz (6.20 MHz, 6.25 MHz, 6.30 MHz), the slope of the increase in the output signal becomes larger in the small distance dr range (e.g., 1 to 3 mm) and the intermediate range (e.g., 4 to 6 mm) compared to when the reference signal R having the same frequency as the resonant frequency of the detected portion 50 is used, but the output characteristics cannot be maintained in the range of more than 7 mm. Furthermore, when the frequency of the reference signal R is 6.25 MHz or 6.30 MHz, the voltage level δ decreases with increasing distance dr in the range of distance dr of 6 mm or more, which is not suitable for detection purposes. On the other hand, if the frequency of the reference signal R is a frequency up to 2% lower than 6.15 MHz, linearity suitable for detection can be obtained. Furthermore, if the frequency of the reference signal R is set to 6.10 MHz, which is about 1% lower than the resonant frequency of the detected portion 50, the linearity of the output characteristic becomes higher.

[0058] In both cases of lowering the Q value of the resonant circuit in the signal generating unit 60 (Measure 1) and lowering the frequency of the reference signal R below the resonant frequency of the detected unit 50 (Measure 2), there exists an optimal solution that maximizes linearity. This optimal solution can be found by numerical analysis using a computer.

[0059] In the embodiment, the outer shapes of the first portion 521, the second portion 522, the third portion 621, and the fourth portion 622 are rectangular including a square, but may be other quadrilaterals such as a rhombus, or may be circular such as a perfect circle or an ellipse. In this case, the center is the intersection of the diagonals in the case of a quadrilateral, the center in the case of a perfect circle, and the intersection of the major axis and the minor axis in the case of an ellipse.

[0060] B: Variation Specific modified embodiments added to each of the above-mentioned embodiments are exemplified below. Two or more embodiments selected from the following examples may be appropriately combined as long as they are not mutually contradictory.

[0061] (1) In each of the above-mentioned embodiments, a configuration for detecting the displacement of the key 12 of the keyboard instrument 100 has been exemplified, but the movable member whose displacement is detected by the displacement sensor 20 is not limited to the key 12. Furthermore, the keyboard structure is not limited to the structure of the above-mentioned examples. Specific examples of movable members different from the above-mentioned examples are exemplified below.

[0062] [Aspect 1] 18 is a schematic diagram of a configuration in which the displacement sensor 20 is applied to a string-striking mechanism 91 of a keyboard instrument 100. The string-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 string-striking mechanism 91 includes, for each key 12, a hammer 911 that can strike a string by rotating, and a transmission mechanism 912 (such as a wippen, jack, or repetition lever) that rotates the hammer 911 in conjunction with the displacement of the key 12. The detected part 50 is mounted on the hammer 911 (e.g., a hammer shank). Furthermore, the signal generating part 60 is mounted on the supporting member 913. In this configuration, the displacement sensor 20 detects the displacement of the hammer 911. Specifically, the supporting member 913 is, for example, a structure that supports the string-striking mechanism 91. Note that the detected part 50 may be mounted on a movable member of the string-striking mechanism 91 other than the hammer 911.

[0063] [Aspect 2] 19 is a schematic diagram of a configuration in which the displacement sensor 20 is applied to a pedal mechanism 92 of a keyboard instrument 100. The pedal mechanism 92 includes a pedal 921 that is operated by the user with the foot, a support member 922 that supports the pedal 921, and an elastic body 923 that biases the pedal 921 upward in the vertical direction. The detected part 50 is disposed on the bottom surface of the pedal 921. Moreover, the signal generating part 60 is disposed on the supporting member 922 so as to face the detected part 50. In this configuration, the displacement sensor 20 detects the displacement of the pedal 921. It should be noted that the instrument in which the pedal mechanism 92 is used is not limited to the keyboard instrument 100. For example, a pedal mechanism 92 having a similar configuration can be used in any other instrument, such as a percussion instrument.

[0064] As can be understood from the above examples, the object of detection by the displacement sensor is generally expressed as a movable member that displaces in response to a performance action. The movable member includes performance operators such as the key 12 or pedal 921 that are directly operated by the user, as well as structures such as the hammer 911 that displace in response to an operation on the performance operator. However, the movable member in this disclosure is not limited to a member that displaces in response to a performance action. In other words, the movable member is generally expressed as a member that can be displaced regardless of the trigger that generates the displacement.

[0065] (2) In the above embodiment, the keyboard instrument 100 is provided with the sound source circuit 34, but in a configuration in which the keyboard instrument 100 is provided with a sound generating mechanism such as a string striking mechanism 91, the sound source circuit 34 may be omitted. The detection system 15 is used to record the performance of the keyboard instrument 100. The sound generating mechanism and the sound source circuit 34 are collectively referred to as a sound generating unit that generates sounds in response to the results of detection by the detection system 15.

[0066] As can be understood from the above description, the present disclosure is also specified as an apparatus (musical performance operation apparatus) that controls musical tones by outputting operation signals corresponding to playing actions to the sound source circuit 34 or the sound generation mechanism. In addition to musical instruments (keyboard instruments 100) equipped with the sound source circuit 34 or the sound generation mechanism as exemplified in each of the above-mentioned forms, the concept of a musical performance operation apparatus also includes devices that do not have the sound source circuit 34 or the sound generation mechanism (for example, a MIDI controller or the pedal mechanism 92 described above). In other words, the musical performance operation apparatus in the present disclosure is comprehensively expressed as an apparatus that a player (operator) operates for playing.

[0067] (3) The above-mentioned measures for improving the linearity of the output characteristic may be implemented either alone or in combination of two or more measures.

[0068] C: Notes From the above-described embodiment, the following aspects can be understood, for example.

[0069] A displacement sensor according to an aspect (first aspect) of the present disclosure is mounted on a movable member that displaces in response to operation, and comprises a detectable part including a first coil, and a signal generating part including a second coil facing the first coil, which generates a detection signal in response to the relative positions of the first coil and the second coil, and an outer dimension of the first coil in a first direction is different from an outer dimension of the first coil in a second direction perpendicular to the first direction in a planar view. According to this aspect, the linearity of the detection signal changes in response to the change in the relative position between the first coil of the detection target and the opposing second coil is improved, so that the detection signal can be generated which reflects the displacement of the movable member with high accuracy, thereby extending the distance measurement range.

[0070] The "external dimension" of a coil in a particular direction means the dimension (size) in that direction with respect to the contour line representing the external shape of the coil, or in other words, the maximum dimension of the coil in that direction.

[0071] In an example of the first aspect (second aspect), the detected part includes a rectangular substrate on which the first coil is formed, 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.

[0072] In another aspect (third aspect) of the present disclosure, an outer dimension of the first coil in the first direction is greater than an outer dimension of the first coil in the second direction.

[0073] Furthermore, a displacement sensor according to another aspect (fourth aspect) of the present disclosure is mounted on a movable member that is displaced in response to operation, and comprises a detectable part including a first coil, and a signal generating part including a second coil facing the first coil, which generates a detection signal in response to the relative positions of the first coil and the second coil, wherein the first coil has a first part and a second part in which magnetic fields of opposite directions are generated by supplying a current to the first coil, and the second coil has a third part and a fourth part in which magnetic fields of opposite directions are generated by supplying a current to the second coil, and a first distance between a center of the first part and a center of the second part is greater than a second distance between a center of the third part and a center of the fourth part. According to this aspect, the linearity of the detection signal changes according to the change in the relative position between the first coil of the detection target and the opposing second coil is improved, so that the detection signal can be generated which reflects the displacement of the movable member with high accuracy. Also, the leakage of the magnetic field generated by the second coil is reduced, so that the detection accuracy can be improved.

[0074] In an example of the fourth aspect (fifth aspect), the first distance is greater than 100% and less than or equal to 140% of the second distance.

[0075] An electronic musical instrument according to one aspect (sixth aspect) of the present disclosure includes a displacement sensor according to any of the aspects exemplified above, and a sound control unit that generates an acoustic signal representing a sound corresponding to the level of the detection signal.

[0076] A displacement sensor according to another aspect (seventh aspect) of the present disclosure is mounted on a movable member that is displaced in response to operation, and comprises a detectable part including a substrate on which a first coil is formed, and a signal generating part including a second coil and generating a detection signal in response to the relative position of the first coil of the detectable part and the second coil facing it, both of which are formed of resonant circuits, and the signal generating part has a resistive element that lowers the Q value, while the detectable part does not have a resistive element that lowers the Q value.

[0077] A displacement sensor according to another aspect (eighth aspect) of the present disclosure is mounted on a movable member that is displaced in response to operation, and comprises a detectable part including a substrate on which a first coil is formed, and a signal generating part including a second coil and generating a detection signal in response to the relative position of the first coil of the detectable part and the second coil facing it, wherein the frequency of the detection signal of the signal generating part is lower than the resonant frequency of the detectable part by up to 2% (i.e., between 98% and 100% of the resonant frequency).

[0078] 100...keyboard instrument (electronic instrument), 10...keyboard, 12...key, 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 emission device, 50...detected portion, 51...first coil, 52...capacitive element, 521...first portion, 522...second portion, 5 51...board, 523...third part, 524...fourth part, 551, 552, 553...board, 60...signal generating unit, 61...second coil, 612...wiring pattern, 621...third part, 622...fourth part, 651...board, 62...capacitive element, 63...capacitive element, 64...resistive element, 911...hammer, 912...transmission mechanism, 913...support member, 921...pedal, 922...support member, 923...elastic body.

Claims

1. a detection target portion including a first coil and disposed on a movable member that is displaced in response to an operation; a signal generating unit including a second coil facing the first coil, the signal generating unit generating a detection signal according to a relative position between the first coil and the second coil; Equipped with The first coil is A first portion; and a second portion located in a first direction of the first portion, In the first portion and the second portion, magnetic fields in mutually opposite directions are generated by supplying a current to the first coil, The second coil is a third portion opposite the first portion; and a fourth portion opposed to the second portion, In the third portion and the fourth portion, magnetic fields in mutually opposite directions are generated by supplying a current to the second coil, a portion of the first portion located in a second direction opposite to the first direction protrudes in the second direction from an edge of the third portion located in the second direction; A portion of the second portion located in the first direction protrudes in the first direction from an edge of the fourth portion located in the first direction. Displacement sensor.

2. 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. The displacement sensor of claim 1 .

3. The first distance is greater than 100% and less than or equal to 140% of the second distance. The displacement sensor of claim 2.

4. A displacement sensor according to any one of claims 1 to 3; a sound control unit that generates an acoustic signal in response to the detection signal; An electronic musical instrument comprising:

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