Displacement sensor and electronic musical instrument

Abstract

The displacement sensor comprises: a detected portion, which is arranged on a movable component that is displaced corresponding to an operation and includes a first coil; and a signal generating portion, which includes a second coil opposite to the first coil and generates a detection signal corresponding to the relative position between the first coil and the second coil, and the outer dimensions of the first coil in a first direction and the outer dimensions of the first coil in a second direction orthogonal to the first direction are different when viewed from above.

Description

Technical Field

[0001] The invention relates to a displacement sensor and an electronic musical instrument. Background Art

[0002] In the past, for example, various technologies for detecting the displacement of movable parts such as keys of keyboard instruments have been proposed. Patent document 1 discloses a structure in which the position of each key is detected using a coil provided on the frame of a keyboard instrument and a metal plate provided on each key. In this structure, if the metal plate is displaced due to the key being pressed, the current flowing in the coil changes. By detecting the current flowing in the coil, a detection signal reflecting the displacement of the key is generated.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 3-48295 Summary of the invention

[0004] However, it is difficult to generate a detection signal that reflects the displacement of a movable member with high accuracy in the technology of Patent Document 1. In view of such a situation, an object of one embodiment of the present invention is to generate a detection signal that reflects the displacement of a movable member with high accuracy.

[0005] In order to achieve the above-mentioned purpose, a displacement sensor involved in one embodiment of the present invention includes: a detected part, which is arranged on a movable part that displaces corresponding to an operation, and includes a first coil; a signal generating part, which includes a second coil opposite to the first coil, and generates a detection signal corresponding to the relative position between the first coil and the second coil, and the outer dimensions of the first coil in the first direction and the outer dimensions of the first coil in the second direction orthogonal to the first direction are different when observed from a top view.

[0006] A displacement sensor according to another embodiment of the present invention comprises: a detected portion, which is arranged on a movable component that is displaced in response to an operation and includes a first coil; and a signal generating portion, which includes a second coil opposite to the first coil and generates a detection signal corresponding to the relative position between the first coil and the second coil, wherein the first coil has a first part and a second part that generate magnetic fields facing in opposite directions by supplying current to the first coil, and the second coil has a third part and a fourth part that generate magnetic fields facing in opposite directions by supplying current to the second coil, and a first distance between the center of the first part and the center of the second part is greater than a second distance between the center of the third part and the center of the fourth part. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a block diagram showing an example of the structure of a keyboard instrument to which a displacement sensor according to one embodiment is applied.

[0008] Figure 2 This is a block diagram showing an example of the structure of a keyboard instrument.

[0009] Figure 3 It is a diagram showing a circuit diagram of a main part of a displacement sensor.

[0010] Figure 4 is a block diagram illustrating an example of a signal processing circuit.

[0011] Figure 5 It is a top view showing the specific structure of the detection part.

[0012] Figure 6 yes Figure 5 Cross-sectional view of line A-a.

[0013] Figure 7 It is an explanatory diagram of the magnetic field etc. generated by the first coil of the detected part.

[0014] Figure 8 It is a top view illustrating a specific structure of a signal generating unit.

[0015] Fig. 9 yes Figure 8 Cross-sectional view of line B-b.

[0016] Fig.10 This is an explanatory diagram of the magnetic field generated by the second coil of the signal generating unit.

[0017] Fig.11 It is a diagram illustrating the positional relationship between the first coil and the second coil.

[0018] Fig.12 It is a top view showing the structure of the detection part involved in the comparative example.

[0019] Fig.13 It is a top view showing the structure of the detection part involved in the comparative example.

[0020] Fig.14 It is a diagram showing an example of the output characteristics of the detection signal.

[0021] Fig.15 It is a diagram showing an example of the output characteristics of the detection signal.

[0022] Fig.16 It is a diagram showing an example of the output characteristics of the detection signal.

[0023] Fig.17 It is a diagram showing an example of the output characteristics of the detection signal.

[0024] Fig.18It is a diagram to which a displacement sensor according to a modified example is applied.

[0025] Fig.19 It is a diagram to which a displacement sensor according to a modified example is applied. DETAILED DESCRIPTION

[0026] A: Implementation Method

[0027] Figure 1 This is a block diagram illustrating the structure of a keyboard musical instrument 100 to which a displacement sensor according to one embodiment of the present invention is applied.

[0028] The keyboard musical 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 part that is displaced in accordance with the performance action of the user. The detection system 15 detects the displacement (position) of the key 12. The information processing device 30 generates an acoustic signal V corresponding to the result of the detection by the detection system 15. The acoustic signal V is a signal representing a musical sound of a pitch corresponding to the key 12 operated by the user. The sound playback device 40 plays the sound represented by the acoustic signal V. For example, a speaker or a headphone is used as the sound playback device 40.

[0029] Figure 2 This is a block diagram showing a 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 on 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 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 of a level corresponding to the position Z of the end 121 in the vertical direction for each of the plurality of keys 12. The position Z is expressed, for example, by the displacement amount of the end 121 with reference to the position of the end 121 in a released state where no load is applied to the key 12.

[0030] 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 for detecting the position of each key 12, and includes a detected portion 50 and a signal generating portion 60. The signal generating portion 60 is provided on the supporting 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 generating portion 60 includes a second coil 61. The first coil 51 and the second coil 61 are spaced apart from each other in the vertical direction and face each other. The distance between the signal generating portion 60 and the detected portion 50 (the distance between the first coil 51 and the second coil 61) changes in accordance with the change in the position Z of the end 121 of the key 12 caused by pressing and releasing the key. The signal processing circuit 21 generates a detection signal D of a level corresponding to the distance between the first coil 51 and the second coil 61.

[0031] 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 including a control device 31, a storage device 32, an A / D converter 33, and a sound source circuit 34.

[0032] The A / D converter 33 converts the detection signal D supplied from the signal processing circuit 21 from analog to digital.

[0033] The control device 31 is composed of a single or multiple processors that control various elements 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).

[0034] 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 instructs the sound source circuit 34 to produce the musical sound corresponding to the position Z of each key 12. The sound source circuit 34 generates an acoustic signal V representing the musical sound instructed by the control device 31. That is, the sound source circuit 34 detects that the key has reached a predetermined position in accordance with the voltage level δ of the detection signal D and starts to generate the acoustic signal V. And, for example, the volume of the acoustic signal V is controlled in accordance with the speed change of the voltage level δ. By supplying the acoustic signal V from the sound source circuit 34 to the sound emitting device 40, the musical sound corresponding to the performance action of the user is emitted from the sound emitting device 40. Specifically, the musical sound is emitted by pressing each key 12 by the user, and the musical sound is stopped by releasing the key 12.

[0035] The storage device 32 is a single memory 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 composed of a well-known recording medium such as a magnetic recording medium or a semiconductor recording medium. In addition, the storage device 32 can also be composed of a combination of multiple recording media. In addition, a mobile recording medium that can be loaded and unloaded with respect to the keyboard instrument 100, or an external recording medium (such as a network hard disk) that can communicate with the keyboard instrument 100 can also 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 an acoustic signal V corresponding to the voltage level δ of the detection signal D.

[0036] Figure 3 2 is a circuit diagram illustrating an electrical configuration of the detected portion 50 and the signal generating portion 60 constituting the displacement sensor 20 .

[0037] The signal generating unit 60 includes an input terminal T1, an output terminal T2, a second coil 61, a capacitor 62, a capacitor 63, and a resistor 64. In the signal generating unit 60, a resonant circuit is formed by the second coil 61, the capacitor 62, the capacitor 63, and the resistor 64. The input terminal T1 is connected to one end of the resistor 64, and the other end of the resistor 64 is connected to one end of the capacitor 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 63. The other end of the capacitor 62 and the other end of the capacitor 63 are grounded to the potential Gnd, which is a reference of voltage zero.

[0038] On the other hand, the detected part 50 includes a first coil 51 and a capacitor 52. One end of the first coil 51 and one end of the capacitor 52 are connected to each other, and the other end of the first coil 51 and the other end of the capacitor 52 are connected to each other. A resonant circuit is formed by the first coil 51 and the capacitor 52. The resonant frequency of the signal generating part 60 is set, for example, based on the relationship with the resonant frequency of the detected part 50. The resonant frequency of the signal generating part 60 is set, for example, to a frequency substantially the same as the resonant frequency of the detected part 50, or to a frequency obtained by multiplying the resonant frequency of the detected part 50 by a predetermined constant.

[0039] The 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 changes periodically. For example, a periodic signal of an arbitrary waveform such as a sine wave is used as the reference signal R. The frequency of the reference signal R is set according to the relationship with the resonant frequency of the detected unit 50. For example, the frequency of the reference signal R is substantially equal to the resonant frequency of the signal generating unit 60 and the detected unit 50.

[0040] A magnetic field is generated in the second coil 61 by supplying a current corresponding to the reference signal R to 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 in a direction that cancels out the change in the magnetic field of the second coil 61 is generated in the first coil 51. The magnetic field generated in the first coil 51 changes in accordance with the distance dr between the first coil 51 and the second coil 61. Therefore, a detection signal d of 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.

[0041] Figure 4 2 is a block diagram illustrating a specific structure 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 plurality of signal generating units 60. The supply circuit 22 supplies the reference signal R to each of the signal generating units 60 in a time-division manner. Specifically, the supply circuit 22 is a demultiplexer that sequentially selects each of the plurality of 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 plurality of signal generating units 60 in a time-division manner. In addition, the period of the reference signal R is sufficiently shorter than the length of time during which one signal generating unit 60 is selected by the supply circuit 22.

[0042] The output circuit 23 generates a detection signal D by arranging the detection signals d sequentially outputted from each of the plurality of signal generating units 60 on the time axis. That is, the detection signal D is 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 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, if 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, the second coil 61 being opposite to the first coil 51. The detection signal D generated by the output circuit 23 is supplied to the information processing device 30.

[0043] Next, the configurations of the detected unit 50 and the signal generating unit 60 will be described.

[0044] Figure 5 1 is a plan view showing a specific structure of the detection unit 50 , and is a view of the detection unit 50 as viewed from the signal generation unit 60 side. Figure 6 yes Figure 5 Cross-sectional view of line A-a.

[0045] The detected part 50 includes a substrate 551 and a wiring pattern provided on the surface F1 and the 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 to be mounted on the setting 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.

[0046] In addition, Figure 5 The vertical direction is the direction in which the keys 12 are arranged, and the horizontal direction is the length direction of one key 12. The width Bw of the detection portion 50 mounted on the installation surface 122 of the key 12 is less than or equal to the width Kw of one key 12.

[0047] In addition, the surface F2 is a surface on the opposite side to the surface F1. Therefore, the surface F2 is opposite to the signal generating unit 60. The first coil 51 of the detected unit 50 is composed of a first part 521 and a second part 522. The first part 521 and the second part 522 are parts of a wiring pattern formed on the surface F2 of the substrate 551. The first part 521 is a part formed in a spiral shape. The second part 522 is a part formed in a shape substantially the same as that of the first part 521. That is, the second part 522 is formed in a spiral shape in the same direction as the winding direction of the first part 521.

[0048] The vortex center of the first portion 521 is the via hole C1, and the vortex center of the second portion 522 is the via hole C2. The via hole C1 and the via hole C2 are electrically connected to each other through the wiring pattern 515 on the surface F1.

[0049] In this embodiment, in the vortex of the first part 521, the straight line extending from the passage hole C1 is bent approximately 90 degrees and expanded outward. The outer shape of the first part 521 is a rectangle. Similarly, for the vortex of the second part 522, the straight line extending from the passage hole C2 is bent approximately 90 degrees and expanded outward. The outer shape of the second part 522 is a rectangle.

[0050] The first part 521 and the second part 522 are rectangular in shape. 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 (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 size Bw of the substrate 551 in the short side direction. The long side direction of the substrate 551 is consistent with the arrangement direction of the first part 521 and the second part 522, that is, the length direction of the key 12. In addition, the short side direction of the substrate 551 is consistent with the lateral direction of the key 12, and the lateral direction of the key 12 is a direction orthogonal to the arrangement direction of the first part 521 and the second part 522.

[0051] Furthermore, the via hole C1 is located at the center of the first portion 521. The center is where the diagonal lines of the rectangular shape of the first portion 521 intersect. Similarly, the via hole C2 is located at the center of the second portion 522. The center is where the diagonal lines of the rectangular shape of the second portion 522 intersect.

[0052] In addition, the distance between the center of the first portion 521 (via hole C1) and the center of the second portion 522 (via hole C2) is defined as L1. In addition, the distance L1 is an example of the first distance.

[0053] The capacitor 52 is mounted between the other end of the first portion 521 when the via hole C1 of the first portion 521 is set as one end and the other end of the second portion 522 when the via hole C2 of the second portion 522 is set as one end. Therefore, the equivalent circuit of the detected portion 50 becomes as follows: Figure 3 In the structure shown in FIG. 1 , a capacitor element 52 is connected to both ends of the first coil 51 .

[0054] In addition, in this embodiment, the first part 521 and the second part 522 are set to the same size and the same shape, but the present invention is not limited to this. For example, the shape or size may be different between the first part 521 and the second part 522. In addition, the planar shape of one or both of the first part 521 and the second part 522 may be set to Figure 5 The longitudinal direction is the length direction, Figure 5 The lateral direction of the first coil 51 is a rectangular shape with the width direction. In addition, the planar shape of the first coil 51 is not limited to the shape including the first portion 521 and the second portion 522. That is, the first coil 51 may be composed of one winding portion.

[0055] Figure 8 2 is a top view showing a specific structure of the signal generating unit 60, and is a view of the signal generating unit 60 as viewed from the side of the detected unit 50. Fig. 9 yes Figure 8 Cross-sectional view of line B-b.

[0056] The signal generating unit 60 includes a substrate 651 and a wiring pattern provided on the surface F3 and the surface F4 of the substrate 651. The substrate 651 is a plate-shaped member having insulating properties. The surface F4 of the signal generating unit 60 is opposite to the supporting member 14. The surface F3 is the surface on the opposite side to the surface F4 and is opposite to 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.

[0057] Figure 8 The up and down directions are multiple keys 12 (in Figure 8 The direction of arrangement (omitted from illustration). Figure 8 The left-right direction is the length direction of one key 12. The length direction of a key 12 is the direction from the front end side (player side) of the key 12 toward the base side of the key 12.

[0058] The second coil 61 of the signal generating 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 part that is roughly square and formed in a spiral shape. The fourth part 622 is a part that is formed in a shape roughly the same 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.

[0059] The vortex center of the third portion 621 is the via hole C11, and the vortex center of the fourth portion 622 is the via hole C12. The via hole C11 and the via hole C12 are electrically connected to each other through the wiring pattern 612 on the surface F4.

[0060] In addition, in the present embodiment, the third part 621 and the fourth part 622 are set to the same size and the same shape, but are not limited to this. For example, the third part 621 and the fourth part 622 may have different sizes. In addition, the third part 621 and the fourth part 622 may also be set to different shapes. In addition, the planar shape of the second coil 61 is not limited to a shape including the third part 621 and the fourth part 622. That is, the second coil 61 may be composed of one winding portion.

[0061] In this embodiment, the third portion 621 has a substantially square outer shape. Similarly, the fourth portion 622 has a substantially square outer shape.

[0062] The direction of one side of the outer shape of the third portion 621 and the fourth portion 622, that is, the square, coincides with the longitudinal direction of the key 12, and the direction perpendicular to the one side coincides with the lateral direction of the key 12. The dimension of one side of the square (outer shape dimension) is B2.

[0063] Furthermore, via C11 is located at the center of the third portion 621, and via C12 is located at the center of the fourth portion 622. The center here refers to the center of the coil when viewed from above, and in the case of a square or rectangle, it is the point where the diagonals intersect, and in the case of a circle, it is the center of the outer circle.

[0064] In addition, the distance between the center of the third portion 621 (via hole C11 in this embodiment) and the center of the fourth portion 622 (via hole C12 in this embodiment) is defined as L2. The distance L2 is an example of the second distance.

[0065] The portion of the wiring pattern on the surface F3 other than the second coil 61 is a wiring for connecting the capacitor element 62 and 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.

[0066] In the above 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. As an example, the dimensional relationship is COW=B2×70%, COL=B2.

[0067] Next, the operation of the circuits of the detected section 50 and the signal generating section 60 will be described. Figure 7 1 is a diagram showing an example of the direction of the magnetic field generated by the detection unit 50 . Fig.10 2 is a diagram showing an example of the direction of the magnetic field generated by the signal generating unit 60 .

[0068] By supplying the reference signal R to the signal generating unit 60, for example, Figure 8 When a counterclockwise current flows through the third portion 621 starting from the via hole C11, a clockwise current flows through the fourth portion 622 toward the via hole C12. Figure 8 The paper front direction and Fig.10 The magnetic field is generated in the upward direction of the fourth part 622. Figure 8 The paper depth direction and Fig.10 A magnetic field is generated in the downward direction.

[0069] That is, Fig.10 As shown in the example, magnetic fields in opposite directions are generated in the third portion 621 and the fourth portion 622. As described above, in the keyboard 10, the plurality of keys 12 are arranged in Fig.10 Therefore, magnetic fields in opposite directions are generated in the third portion 621 and the fourth portion 622, thereby reducing the diffusion of the magnetic field generated in the signal generating unit 60 relative to each of the adjacent keys 12. As a result of reducing the diffusion of the magnetic field, a detection signal D is generated that reflects the position Z of each of the multiple keys 12 with high accuracy.

[0070] In addition, Fig.10 , exemplifying Figure 8 In the case where a current flows counterclockwise in the third portion 621 and a current flows clockwise in the fourth portion 622. In the case where a current flows clockwise in the third portion 621 and a current flows counterclockwise in the fourth portion 622, the directions of the magnetic fields are also opposite.

[0071] The third part 621 and the fourth part 622 of the second coil 61 of the signal generating unit 60 are formed by patterning the conductive layer of the surface F4. Therefore, there is an advantage that, for example, the second coil 61 is easy to manufacture and handle compared to a structure in which the second coil 61 is formed by winding a conductive wire.

[0072] As described above, in a state where the reference signal R is supplied to the signal generating 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 (that is, 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 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.

[0073] For example, when the second coil 61 of the signal generating unit 60 generates Fig.10In the state of the magnetic field in the direction shown, when the first coil 51 of the detected part 50 moves in the 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.

[0074] Therefore, in Figure 5 , the current flows clockwise in the first portion 521 of the first coil 51 , and the current flows counterclockwise in the second portion 522 .

[0075] In addition, when the second coil 61 of the signal generating unit 60 generates Fig.10 In the state of the magnetic field in the direction shown, when the first coil 51 of the detected part 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.

[0076] Therefore, in Figure 5 , in the first portion 521 of the first coil 51 , the current flows counterclockwise, and in the second portion 522 , the current flows clockwise.

[0077] In addition, the second coil 61 generates Fig.10 In the state of the magnetic field in the opposite direction to the direction of the example, when the first coil 51 is close to the second coil 61, the first coil 51 generates a magnetic field in the opposite direction to the magnetic field generated by the second coil 61, that is, Figure 7 The magnetic field as shown.

[0078] In addition, when the second coil 61 generates Fig.10 The first coil 51 approaches the second coil 61 in the state of the magnetic field in the direction shown, and the second coil 61 generates a magnetic field in the direction shown. Fig.10 When the first coil 51 is away from the second coil 61 in the state of the magnetic field in the opposite direction shown, the current flows clockwise in the first portion 521 of the first coil 51 and the current flows counterclockwise in the second portion 522 .

[0079] Next, the structure and processing for improving the linearity related to the output characteristics of the detection signal in the detection system 15, that is, extending the detection distance, will be described. The output characteristic is the relationship between the distance dr and the voltage level δ of the detection signal d, and the distance dr is the distance between the first coil 51 and the second coil 61. The linearity of the output characteristic means that the relationship between the voltage level δ and the distance dr is close to a proportional relationship. In addition, the detection distance refers to 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 refers to the range of the distance dr reflected in the voltage level δ.

[0080] In order to improve the linearity of the output characteristics, in this embodiment, the distance L1 (first distance) between the center of the first part 521 and the center of the second part 522 is greater than the distance L2 (second distance) between the center of the third part 621 and the center of the fourth part 622.

[0081] Fig.11 1 is a plan view showing the positional relationship between the first coil 51 and the second coil 61 in a state where the detection unit 50 is mounted on the installation surface 122 of the key 12 and the signal generation unit 60 is installed on the support member 14. Fig.11 It is a plan view showing the first portion 521 and the second portion 522 of the first coil 51 and the third portion 621 and the fourth portion 622 of the second coil 61 viewed from the detected portion 50 toward the signal generating portion 60 in the above state.

[0082] The via holes C1, C2, C11, and C12 are located on a straight line Ln along the longitudinal direction of the key 12. In addition, the via holes C11 and C12 are located between the via hole C1 and the via hole C2.

[0083] In the displacement sensor 20 according to the present embodiment, the distance L1 between the center of the first portion 521 and the center of the second portion 522 of the detected portion 50 is greater than the distance L2 between the center of the third portion 621 and the center of the fourth portion 622 of the signal generating portion 60. Here, the effectiveness of the structure in which the distance L1 is greater than the distance L2 is first described.

[0084] The output characteristics are compared between the structure A and the structure B in which the distance L1 and the distance L2 are different. Fig.12 The structure shown in FIG. 1 is that the distance L1 of the first coil 51 is greater than the distance L2. Fig.13 The structure shown is that the distance L1 of the first coil 51 is smaller than the distance L2.

[0085] Specifically, in Fig.12 , the distance L1 is Figure 8 L2×120% shown in Fig.13 , the distance L1 is L2×80%. In addition, Fig.12 The dimensions of COL and COW and Fig.13 The dimensions of COL and COW are Figure 8 The signal generating unit 60 for this comparison uses Figure 8 structure.

[0086] Fig.14 is a diagram showing the output characteristics of the displacement sensor 20 of the structure A and the structure B. Fig.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. Fig.14 , the solid line indicates Fig.12 The output characteristics of structure A are shown, and the dotted line indicates Fig.13 The output characteristics of the structure B are shown. In the structure A, the output voltage increases even when the distance dr exceeds 10 mm, whereas in the structure B, the output voltage does not change (becomes substantially constant) when the distance dr exceeds 8 mm.

[0087] That is, by comparing the output characteristics of the structures A and B, it can be seen that: in the solid line structure A, the range of the distance dr of the output change of the detection signal d is larger than that of the dotted line structure B, that is, the range that the displacement sensor 20 can detect is larger. In other words, in the solid line structure A, a higher linearity is obtained in the output characteristics compared to the dotted line structure B.

[0088] In addition, 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 of the detection unit 50 are not Fig.12 The square shown becomes a rectangle extending along the length direction of the key 12.

[0089] Furthermore, it is preferable that the area that functions as the coil is large in the first part 521 and the second part 522. Therefore, in the present embodiment, the outer shape of each of the first part 521 and the second part 522 of the detected portion 50 is set to be a rectangle 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 larger than the outer dimension COW. Specifically, in the present embodiment, the dimension ratio between the outer dimension COW and the outer dimension COL in each of the first part 521 and the second part 522 is set to 7:10.

[0090] Next, the relationship between the distance L1 and the distance L2 is studied. Fig.15 This is a graph showing the output characteristics when the ratio (%) of the distance L1 with respect to the distance L2 as the reference is changed to 100%, 120%, 140%, and 160%. In addition, for comparison, the voltage level δ on the vertical axis is standardized so that the minimum value is "0" and the maximum value is "1". The signal generation unit 60 used in this study uses Figure 8 structure.

[0091] The index (e.g., R-squared value) indicating linearity among the four output characteristics shown in the figure is the highest when the distance L1 is L2×120%, and the lowest when the distance L1 is L2×160%. Therefore, from the viewpoint of ensuring linearity, the distance L1 is preferably a value within a range including values ​​before and after 120% based on the distance L2. Specifically, the distance L1 is set to a value within a range greater than 100% and less than or equal to 140% relative to the distance L2 (L2<L1≤1.4×L2).

[0092] As described above, if the distance L1 is set to be within the above range relative to the distance L2, the magnetic field generated in the second coil 61 is appropriately 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 to be within the above range relative to the distance L2, 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 compared to the case where the distance L1 is set outside the above range.

[0093] 1: Measures to improve the linearity of output characteristics 1

[0094] In addition to the above-mentioned embodiment, as a measure for improving the linearity of the output characteristic, first, a resistor element 64 is used as a damping resistor in the resonance circuit of the signal generation unit 60 to reduce the Q factor (Quality Factor) of the resonance circuit.

[0095] Fig.16 It means to make Figure 3 Graph showing output characteristics when the resistance value of the resistor element 64 of the circuit changes stepwise. Fig.16 , the output characteristics are shown for each of the cases where the resistance value of the resistor element 64 is changed to six values, such as 0, 100, 200, 300, 400, and 500Ω.

[0096] exist Fig.16, in the state without the resistor element 64 (0Ω), that is, in the state with the highest Q value, the following characteristics are obtained, that is, when the distance dr slightly exceeds 5mm, the voltage level δ of the detection signal d is the largest, and thereafter, the voltage level δ decreases relative to the increase in the distance dr. Therefore, as the detection range, only a narrow range of about 1 to 5mm can be used. However, in the state where the resistor element 64 of 100Ω is used in a manner to reduce the Q value, the following characteristics are obtained, that is, even in the range where the distance dr exceeds 5mm, the voltage level δ of the detection signal d increases little by little relative to the increase in the distance dr. Moreover, as the resistance value of the resistor element 64 increases, the variation range of the voltage level δ gradually decreases in each of the range where the distance dr is small (for example, 1 to 3mm), the range where the distance dr is large (for example, 8 to 10mm), and the range between them (for example, 4 to 6mm).

[0097] As described above, as the resistance value of the resistor element 64 of the signal generating unit 60 increases, the Q value decreases and the linearity of the output characteristic increases. That is, the detection distance can be increased.

[0098] In addition, no resistance element as a damping resistor is provided in the detected portion 50. This is because sufficient detection characteristics can be obtained even without reducing the Q value. However, for the stability of detection and the mass production of the device, a resistance element as a damping resistor may be provided in the detected portion 50.

[0099] 2: Measures to improve the linearity of output characteristics 2

[0100] In addition, as another measure for improving the linearity of the output characteristics, the frequency of the reference signal R supplied to the input terminal T1 is reduced by a maximum of 2% compared to the resonant frequency of the detected part 50 (i.e., between 98% and 100% of the resonant frequency), and more preferably by approximately 1% lower than the resonant frequency of the detected part 50.

[0101] Fig.17 This is a diagram showing the output characteristics when the resonance frequency of the detection unit 50 (the reactance of the first coil 51 is 3.04 μH, and the capacitance of the capacitor 52 is 220 pF) is set to 6.15 MHz and the frequency of the reference signal R is changed stepwise. Fig.17 In FIG. 1 , the output characteristics are shown for each case where the frequency of the reference signal R is changed to 7 values: 6.00 MHz, 6.05 MHz, 6.10 MHz, 6.15 MHz, 6.20 MHz, 6.25 MHz, and 6.30 MHz. Fig.17When the frequency of the reference signal R is a frequency higher than 6.15MHz (6.20MHz, 6.25MHz, 6.30MHz), the slope of the increase of the output signal in the range of small distance dr (e.g., 1 to 3mm) and the middle range (e.g., 4 to 6mm) becomes larger than the case when the reference signal R with the same frequency as the resonant frequency of the detected part 50 is used, but the output characteristic cannot be maintained in the range greater than 7mm. Furthermore, when the frequency of the reference signal R is 6.25MHz and 6.30MHz, in the range of distance dr being more than 6mm, the voltage level δ decreases with the increase of the distance dr, which is not suitable for detection purposes. On the other hand, if the frequency of the reference signal R is a frequency that is at most 2% lower than 6.15MHz, a linearity suitable for detection can be obtained. Furthermore, if the frequency of the reference signal R is set to 6.10MHz, which is about 1% lower than the resonant frequency of the detected part 50, the linearity of the output characteristic is higher.

[0102] In addition, in both the case of reducing the Q value of the resonant circuit of the signal generating unit 60 (measure 1) and the case of setting the frequency of the reference signal R lower than the resonant frequency of the detected unit 50 (measure 2), there is an optimal solution that maximizes the linearity. This optimal solution can be obtained by numerical analysis based on a computer.

[0103] In the embodiment, the outer shape of the first part 521, the second part 522, the third part 621, and the fourth part 622 is set to a rectangle including a square, but it can also be a rhombus or other quadrilateral, or a true circle, an ellipse or other circular shape. In addition, the center in the above case is the intersection of the diagonal lines in the case of a quadrilateral, the center in the case of a true circle, and the intersection of the major axis and the minor axis in the case of an ellipse.

[0104] B: Deformation

[0105] Specific variations of the above-exemplified embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following embodiments may be combined as appropriate within the range that they do not contradict each other.

[0106] (1) In each of the above-mentioned embodiments, a structure for detecting the displacement of the key 12 of the keyboard musical instrument 100 is exemplified, and the movable member whose displacement is detected 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-mentioned examples. The following exemplifies a specific embodiment of the movable member different from the above-mentioned examples.

[0107] [Method 1]

[0108] Fig.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.

[0109] 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.

[0110] [Method 2]

[0111] Fig.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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] (2) In the above-mentioned embodiments, the keyboard instrument 100 is provided with the sound source circuit 34. However, in a configuration where the keyboard instrument 100 has a sound producing mechanism such as the 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 producing mechanism and the sound source circuit 34 collectively represent a sound generating section that generates sound in accordance with the detection result of the detection system 15.

[0116] As understood from the above description, the present invention is also defined as a device (performance operation device) that controls musical sounds by outputting an operation signal corresponding to a performance action to a sound source circuit 34 or a sound producing mechanism. As exemplified in the above-mentioned embodiments, in addition to a musical instrument (keyboard instrument 100) having a sound source circuit 34 or a sound producing mechanism, a device (such as a MIDI controller or the above-mentioned pedal mechanism 92) that does not have a sound source circuit 34 or a sound producing mechanism is also included in the concept of a performance operation device (instrument playing apparatus). That is, the performance operation device of the present invention is generally expressed as a device that a performer (operator) operates for performance.

[0117] (3) The above-mentioned measures for improving the linearity of the output characteristics may be implemented alone, or two or more measures may be appropriately used in combination.

[0118] C: Appendix

[0119] According to the above-exemplified embodiment, for example, the following configurations can be understood.

[0120] The displacement sensor involved in the mode (first mode) of the present invention comprises: a detected part, which is arranged on a movable part that displaces corresponding to an operation, and includes a first coil; and a signal generating part, which includes a second coil opposite to the first coil, and generates a detection signal corresponding to the relative position between the first coil and the second coil, and the outer dimensions of the first coil in the first direction and the outer dimensions of the first coil in the second direction orthogonal to the first direction are different when observed from a top view.

[0121] According to this method, the linearity of the detection signal changes in accordance with the change in the relative position between the first coil of the detected part and the second coil is improved, so that a detection signal that reflects the displacement of the movable member with high accuracy can be generated. Therefore, the ranging distance can be extended.

[0122] The “outer dimensions” of a coil in a specific direction refers to the dimension (size) in the corresponding direction relative to the outline representing the outer shape of the coil, and may also be referred to as the maximum value of the dimension of the coil in the corresponding direction.

[0123] In the example of the first method (the second method), the detected portion 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 dimensions of the first coil in the second direction are smaller than or equal to the dimensions of the substrate in the short side direction.

[0124] In another aspect (third aspect) of the present invention, an outer dimension of the first coil in the first direction is larger than an outer dimension of the first coil in the second direction.

[0125] In addition, the displacement sensor involved in another embodiment of the present invention (the fourth embodiment) has: a detected part, which is arranged on a movable part that displaces corresponding to an operation, and includes a first coil; and a signal generating part, which includes a second coil opposite 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 part and a second part that generate magnetic fields facing in opposite directions by supplying current to the first coil, and the second coil has a third part and a fourth part that generate magnetic fields facing in opposite directions by supplying current to the second coil, and a first distance between the center of the first part and the center of the second part is greater than a second distance between the center of the third part and the center of the fourth part.

[0126] According to this method, the linearity of the detection signal when it changes in accordance with the change in the relative position between the first coil of the detected part and the second coil is improved, so that a detection signal that reflects the displacement of the movable part with high accuracy 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.

[0127] In the example of the fourth aspect (fifth aspect), the first distance is greater than 100% of the second distance and less than or equal to 140% of the second distance.

[0128] An electronic musical instrument according to one aspect (sixth aspect) of the present invention includes: a displacement sensor according to any of the above-exemplified aspects; and a sound control unit that generates an acoustic signal representing a sound corresponding to a level of the detection signal.

[0129] The displacement sensor involved in another embodiment of the present invention (the seventh embodiment) comprises: a detected part, which is arranged on a movable part that displaces corresponding to an operation, and includes a substrate on which a first coil is formed; and a signal generating part, which includes a second coil and generates a detection signal corresponding to the relative position between the first coil and the second coil of the detected part, the second coil is opposite to the first coil, the detected part and the signal generating part are both formed by a resonant circuit, the signal generating part has a resistance element that reduces the Q value, and the detected part does not have a resistance element that reduces the Q value.

[0130] Another embodiment of the present invention (the eighth embodiment) involves a displacement sensor comprising: a detected portion, which is arranged on a movable component that displaces in response to an operation, and includes a substrate on which a first coil is formed; and a signal generating portion, which includes a second coil and generates a detection signal corresponding to the relative position between the first coil and the second coil of the detected portion, the second coil being opposite to the first coil, and the frequency of the detection signal of the signal generating portion differs from the resonant frequency of the detected portion by a maximum of 2% (i.e., between 98% and 100% of the resonant frequency).

[0131] 100…keyboard instrument (electronic musical 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 playback device, 50…detected portion, 51…first coil, 52…capacitor, 521…first part, 522…second part, 551…substrate, 523…third part, 524…fourth part, 551, 552, 553…substrate, 60…signal generating unit, 61…second coil, 612…wiring pattern, 621…third part, 622…fourth part, 651…substrate, 62…capacitor element, 63…capacitor element, 64…resistor element, 911…hammer, 912…transmission mechanism, 913…support component, 921…pedal, 922…support component, 923…elastic body.

Claims

1. A displacement sensor, comprising: a detected portion provided on a movable member that is displaced in response to the operation, and comprising a first coil; and a signal generating unit including a second coil facing the first coil, and generating a detection signal corresponding to a relative position between the first coil and the second coil; The first coil includes a first portion and a second portion that generate magnetic fields directed in opposite directions to each other when current is supplied to the first coil. The second coil has a third portion and a fourth portion which generate magnetic fields directed in opposite directions to each other when current is supplied to the second coil. 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.

2. The displacement sensor according to claim 1, wherein: The first distance is greater than 100% of the second distance and less than or equal to 140% of the second distance.

3. An electronic musical instrument comprising: The displacement sensor according to claim 1 or 2; and The sound control unit generates an acoustic signal representing a sound corresponding to the level of the detection signal.

Images