Detection Systems and Instruments

Abstract

In the present invention, a first detection coil is provided to a first key, and a second detection coil is provided to a second key. A first signal generation unit includes a first drive coil that is opposite from the first detection coil, and generates a first detection signal in accordance with the distance between the first detection coil and the first drive coil. A second signal generation unit includes a second drive coil that is opposite from the second detection coil, and generates a second detection signal in accordance with the distance between the second detection coil and the second drive coil. The first drive coil includes a first drive part in which current flows in a first direction, and a second drive part in which current flows in a second direction that is opposite to the first direction. The second drive coil includes a third drive part in which current flows in the first direction, and a fourth drive part in which current flows in the first direction. The first detection coil includes a first portion and a second portion in which induced currents in opposite directions to each other are generated via electromagnetic induction by the first drive coil. The second detection coil includes a third portion and a fourth portion in which induced currents in the same direction as each other are generated via electromagnetic induction by the second drive coil.

Description

[Technical Field]

[0001] The present disclosure relates to techniques for detecting the position of a movable member. [Background technology]

[0002] Various techniques for detecting the position of a movable part have been proposed. For example, Patent Document 1 discloses a detection system that includes an active resonant circuit installed on the body of a keyboard instrument and a passive resonant circuit installed on each key. The active resonant circuit includes a coil that generates a magnetic field when supplied with a periodic signal, and generates a detection signal corresponding to the distance between the active resonant circuit coil and the coil of the passive resonant circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 122867 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the magnetic field generated by the coil of the active resonant circuit corresponding to one key affects the coil of the passive resonant circuit of another key adjacent to that key. This type of interaction between adjacent keys may hinder highly accurate detection of each key. While the above description illustrates key detection, similar issues can be expected in any configuration in which multiple movable members are in close proximity. Taking the above circumstances into consideration, one aspect of the present disclosure aims to detect the position of each of multiple movable members with high accuracy. [Means for solving the problem]

[0005] In order to solve the above problems, a detection system according to one aspect of the present disclosure includes a first detection coil installed on a first movable member, a second detection coil installed on a second movable member, a first drive coil facing the first detection coil, and a first signal generation unit that generates a first detection signal according to the distance between the first detection coil and the first drive coil, and a second signal generation unit that includes a second drive coil facing the second detection coil, and generates a second detection signal according to the distance between the second detection coil and the second drive coil, The detecting coil includes a first driving unit in which current flows in a first direction and a second driving unit in which current flows in a second direction opposite to the first direction, the second driving coil includes a third driving unit in which current flows in the first direction and a fourth driving unit in which current flows in the first direction, the first detecting coil includes a first portion and a second portion in which induced currents in opposite directions are generated by electromagnetic induction of the first driving coil, and the second detecting coil includes a third portion and a fourth portion in which induced currents in the same direction are generated by electromagnetic induction of the second driving coil.

[0006] A musical instrument according to one aspect of the present disclosure includes a first movable member and a second movable member that move in response to a performance operation by a user, a first detection coil provided on the first movable member, a second detection coil provided on the second movable member, a first drive coil facing the first detection coil, and a first signal generation unit that generates a first detection signal according to the distance between the first detection coil and the first drive coil, and a second signal generation unit that includes a second drive coil facing the second detection coil, and generates a second detection signal according to the distance between the second detection coil and the second drive coil. the first drive coil includes a first drive unit in which a current flows in a first direction and a second drive unit in which a current flows in a second direction opposite to the first direction; the second drive coil includes a third drive unit in which a current flows in the first direction and a fourth drive unit in which a current flows in the first direction; the first detector coil includes a first portion and a second portion in which induced currents in opposite directions are generated by electromagnetic induction of the first drive coil; and the second detector coil includes a third portion and a fourth portion in which induced currents in the same direction are generated by electromagnetic induction of the second drive coil. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram illustrating the configuration of a keyboard instrument according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating the configuration of a keyboard instrument. [Figure 3] FIG. 2 is a circuit diagram of a signal generating unit and a detected unit. [Figure 4] FIG. 2 is a block diagram illustrating the configuration of a drive circuit. [Figure 5] 10 is a flowchart of a control process. [Figure 6] FIG. 10 is a schematic diagram of a correlation table. [Figure 7] 3 is a schematic diagram of a signal generating section and a detected section. FIG. [Figure 8] FIG. 2 is a plan view of a first signal generating unit. [Figure 9] 9 is a cross-sectional view taken along line aa in FIG. 8. [Figure 10] FIG. 4 is a plan view of a second signal generating unit. [Figure 11] 11 is a cross-sectional view taken along the line bb in FIG. 10. [Figure 12] FIG. 4 is a plan view of a first detection part. [Figure 13] FIG. 13 is a cross-sectional view taken along the line cc in FIG. [Figure 14] FIG. 4 is a plan view of a second detection target portion. [Figure 15] FIG. 15 is a cross-sectional view taken along the line dd in FIG. [Figure 16] FIG. 2 is an explanatory diagram of the operation of the detection system. [Figure 17] This is the relationship between the position of the key and the signal level of the detection signal. [Figure 18] FIG. 18 is an explanatory diagram of each sample in FIG. 17. [Figure 19] This is the relationship between the position of the key and the signal level of the detection signal. [Figure 20] FIG. 20 is an explanatory diagram of each sample in FIG. 19. [Figure 21] FIG. 10 is an explanatory diagram of the operation of the detection system in the second embodiment. [Figure 22] FIG. 11 is a schematic diagram of a correlation table in the third embodiment. [Figure 23] FIG. 10 is an explanatory diagram regarding the difference in position-level characteristics between the first key and the second key. [Figure 24] FIG. 11 is a plan view of a first detection part in the fourth embodiment. [Figure 25] FIG. 13 is a plan view of a second detected portion in a modified example of the fourth embodiment. [Figure 26] FIG. 10 is a schematic diagram of a string-striking mechanism in a modified example. [Figure 27] FIG. 10 is a schematic diagram of a pedal mechanism according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] A: First embodiment FIG. 1 is a block diagram illustrating the configuration of a keyboard instrument 100 according to a first embodiment of the present disclosure. The keyboard instrument 100 is an electronic musical instrument comprising a keyboard unit 20, a control system 30, and a sound output system 40. In the following description, three mutually orthogonal axes (X-axis, Y-axis, and Z-axis) are assumed. The X-axis is an axis extending in the left-right direction (width direction) of the keyboard instrument 100. The Y-axis is an axis extending in the front-back direction (depth direction) of the keyboard instrument 100. In other words, the XY plane is parallel to the horizontal plane. The Z-axis is an axis extending in the up-down direction (vertical direction) of the keyboard instrument 100. The direction of the X-axis is an example of a "specific direction."

[0009] The keyboard unit 20 is an input device that accepts performance operations by the user, and includes a keyboard 21 and a detection system 25. The keyboard 21 is composed of a plurality of keys 22 that correspond to different pitches. The plurality of keys 22 includes a plurality of white keys and a plurality of black keys, and are arranged in the X direction. Each key 22 is configured as an elongated member along the Y axis, and is a movable member that moves in the Z axis direction in response to performance operations by the user. Performance operations are key pressing or key release. The detection system 25 detects the position P of each key 22 in the Z axis direction.

[0010] The control system 30 generates an audio signal V according to the result of detection by the detection system 25. The audio signal V is a signal representing a musical tone having a pitch corresponding to the key 22 operated by the user. The control system 30 may be configured separately from the keyboard instrument 100. For example, a general-purpose information processing device such as a smartphone, a tablet terminal, or a personal computer may be used as the control system 30.

[0011] The sound emission system 40 emits musical sounds represented by the acoustic signal V. For example, one or more speakers, or headphones (earphones) worn on the user's head, are used as the sound emission system 40. Note that the sound emission system 40 configured separately from the keyboard instrument 100 may be connected to the keyboard instrument 100 by wire or wirelessly.

[0012] FIG. 2 is a schematic diagram illustrating the configuration of a keyboard instrument 100. Each key 22 of a keyboard 21 is supported by a support 24 with a balance pin 23 as a fulcrum. The support 24 is a structure that supports each element of the keyboard instrument 100. The tip of each key 22 moves in the direction of the Z axis in response to a user's performance manipulation. A detection system 25 generates an observation signal Q that represents a position P of each of the multiple keys 22. The position P is, for example, the surface position of the tip of the key 22. The position P is expressed, for example, as the amount of movement based on the position of each key 22 when it is not being manipulated.

[0013] The detection system 25 comprises a plurality of signal generating units 50, a plurality of detected units 60, and a drive circuit 70. A signal generating unit 50 and a detected unit 60 are provided for each key 22. Each signal generating unit 50 is provided on the support 24. That is, the position of each signal generating unit 50 is fixed. A detected unit 60 corresponding to each key 22 is provided on that key 22. Specifically, the detected unit 60 is provided on the bottom surface 221 of the key 22. Therefore, the position of the detected unit 60 in the Z-axis direction changes in response to the user's playing operation.

[0014] The signal generating unit 50 includes a drive coil La. The detected unit 60 includes a detection coil Lb. The drive coil La and the detection coil Lb face each other with a gap in the Z direction. The distance between the signal generating unit 50 and the detected unit 60 (the distance between the drive coil La and the detection coil Lb) changes depending on the position P of the key 22. In the first embodiment, the detected unit 60 is installed between the rear end of the key 22 and the balance pin 23. Therefore, when the user presses a key, the distance between the drive coil La and the detection coil Lb increases. The drive circuit 70 generates an observation signal Q with a signal level that corresponds to the distance between the drive coil La and the detection coil Lb.

[0015] 3 is a circuit diagram illustrating the electrical configuration of the signal generating unit 50 and the detected unit 60 corresponding to any one key 22. The signal generating unit 50 is a resonant circuit including an input terminal T1, an output terminal T2, a resistive element R, a driving coil La, and capacitive elements Ca1 and Ca2. One end of the resistive element R is connected to the input terminal T1, and the other end of the resistive element R is connected to one end of the capacitive element Ca1 and one end of the driving coil La. The other end of the driving coil La is connected to the output terminal T2 and one end of the capacitive element Ca2. The other end of the capacitive element Ca1 and the other end of the capacitive element Ca2 are grounded (Gnd).

[0016] The detected portion 60 is a resonant circuit including a detection coil Lb and a capacitance element Cb. One end of the detection coil Lb is connected to one end of the capacitance element Cb, and the other end of the detection coil Lb is connected to the other end of the capacitance element Cb. In the first embodiment, the resonant frequency of the signal generating portion 50 and the resonant frequency of the detected portion 60 are set to be equal to each other. However, the resonant frequency of the signal generating portion 50 and the resonant frequency of the detected portion 60 may be different. For example, the resonant frequency of the signal generating portion 50 is set to a frequency obtained by multiplying the resonant frequency of the detected portion 60 by a predetermined constant.

[0017] FIG. 4 is a block diagram illustrating a specific configuration of the drive circuit 70. The drive circuit 70 includes a supply circuit 71 and an output circuit 72. The supply circuit 71 supplies a drive signal W to the input terminal T1 of each signal generating unit 50. For example, the supply circuit 71 is a demultiplexer that supplies the drive signal W to each of the multiple signal generating units 50 in a time-division manner for each predetermined period (hereinafter referred to as a "drive period"). The drive signal W is a signal whose signal level fluctuates periodically. For example, a periodic signal with an arbitrary waveform, such as a sine wave or a rectangular wave, is used as the drive signal W. The period of the drive signal W is sufficiently shorter than the duration of the drive period during which the drive signal W is supplied to one signal generating unit 50. The frequency of the drive signal W is set to a frequency approximately equal to the resonant frequency of the signal generating unit 50 and the detected unit 60.

[0018] The drive signal W is supplied to the drive coil La via the input terminal T1 and the resistive element R. The supply of the drive signal W generates a magnetic field in the drive coil La. Electromagnetic induction caused by the magnetic field generated by the drive coil La generates an induced current in the detection coil Lb of the detected part 60. In other words, a magnetic field is generated by the detection coil Lb in a direction that offsets the change in the magnetic field of the drive coil La. The magnetic field generated by the detection coil Lb changes depending on the distance between the drive coil La and the detection coil Lb. Therefore, a detection signal D with an amplitude δ corresponding to the distance between the drive coil La and the detection coil Lb is output from the output terminal T2. The detection signal D is a periodic signal with the same frequency as the drive signal W. The amplitude δ of the detection signal D changes depending on the position P of the key 22.

[0019] The output circuit 72 in FIG. 4 is a multiplexer that generates an observation signal Q by arranging, on a time axis, the detection signals D output from each signal generation unit 50 for each drive period. Specifically, the output circuit 72 rectifies (full-wave or half-wave rectification) and smoothes the detection signals D output from the signal generation unit 50 for each drive period, and generates the observation signal Q by arranging the smoothed signals for each drive period on a time axis. As can be understood from the above explanation, the observation signal Q is set to a signal level that corresponds to the position P of each key 22 for each drive period. Specifically, the signal level of the observation signal Q increases as the distance between the drive coil La and the detection coil Lb increases. The signal level of the observation signal Q in each drive period corresponds to the signal level of the detection signal D generated by the signal generation unit 50 for that drive period.

[0020] 2 analyzes the position P of each key 22 by analyzing the observation signal Q supplied from the drive circuit 70. The control system 30 is realized by a computer system equipped with a control device 31, a storage device 32, an A / D converter 33, and a sound source circuit 34. The control system 30 may be realized as a single device, or may be realized as multiple devices configured separately from each other.

[0021] The control device 31 is composed of one or more processors that control each element of the keyboard instrument 100. Specifically, the control device 31 is composed of one or more types of processors, such as a CPU (Central Processing Unit), a GPU (Graphics 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).

[0022] The storage device 32 is one or more memories that store programs executed by the control device 31 and 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 also be configured with a combination of multiple types of storage medium. The storage device 32 may also be a portable storage medium that can be attached to or detached from the keyboard instrument 100, or an external storage medium (e.g., online storage) with which the keyboard instrument 100 can communicate.

[0023] The A / D converter 33 converts the observation signal Q supplied from the drive circuit 70 from analog to digital. The sound source circuit 34 generates an audio signal V representing a musical tone instructed by the control device 31. Specifically, the audio signal V represents a musical tone of a pitch corresponding to the key 22 whose position P has changed among a plurality of pitches. The volume of the audio signal V is controlled, for example, according to the speed at which the position P changes. The audio signal V is supplied from the sound source circuit 34 to the sound emission system 40, causing a musical tone corresponding to the user's performance operation to be emitted from the sound emission system 40. Note that the control device 31 may implement the function of the sound source circuit 34 by executing a program stored in the storage device 32. In other words, the element (sound source unit) that generates the audio signal V may be either a software sound source implemented by the general-purpose control device 31 or a hardware sound source implemented by a dedicated electronic circuit.

[0024] FIG. 5 is a flowchart of the process (hereinafter referred to as the "control process") executed by the control device 31. For example, the control process is repeated for each drive period. That is, the control process of FIG. 5 is executed for each key 22. When the control process starts, the control device 31 determines the signal level E of each detection signal D from the observation signal Q converted by the A / D converter 33 (S1). The signal level E in each drive period is a voltage value corresponding to the amplitude δ of the detection signal D generated by the signal generation unit 50 during that drive period. That is, the signal level E is set to a voltage value corresponding to the position P of one key 22 corresponding to the drive period.

[0025] The control device 31 identifies the position P of each key 22 from the signal level E (S2). For example, the correlation table F shown in FIG. 6 is used to analyze the position P of each key 22. The correlation table F is a data table in which the position P (P1, P2, ...) of each key 22 is set for each of a plurality of possible values ​​(E1, E2, ...) of the signal level E of the detection signal D (observation signal Q). The control device 31 searches the correlation table F for the signal level E identified from the observation signal Q, and identifies the position P of the key 22 that corresponds to the signal level E among the plurality of positions P. Note that the control device 31 may calculate the position P by a predetermined calculation that applies the signal level E. As can be understood from the above explanation, the control device 31 functions as an element (position analysis unit) that identifies the position of the key 22 from the signal level E of the detection signal D.

[0026] The control device 31 controls the tone generator circuit 34 in accordance with the position P of each key 22 (S3). Specifically, the control device 31 determines whether or not each key 22 has been pressed in accordance with the position P of the key 22, and instructs the tone generator circuit 34 to generate a musical tone corresponding to the key 22 pressed by the user. The tone generator circuit 34 generates an audio signal V representing the musical tone instructed by the control device 31.

[0027] Fig. 7 is a schematic diagram of the signal generating section 50 and the detected section 60. Note that the vertical dashed line in Fig. 7 indicates the positional correspondence between the signal generating section 50 and the detected section 60 (the detected section 60 is located directly above the signal generating section 50).

[0028] The multiple keys 22 constituting the keyboard 21 are divided into first keys 22a and second keys 22b that are adjacent to each other. For example, the odd-numbered keys 22 among the multiple keys 22 correspond to the first keys 22a, and the even-numbered keys 22 among the multiple keys 22 correspond to the second keys 22b. Therefore, the first keys 22a and the second keys 22b are arranged alternately in the X-axis direction. The first keys 22a are an example of a "first movable member," and the second keys 22b are an example of a "second movable member." Note that, for convenience, the multiple keys 22 are shown in FIG. 7 as having the same shape, but the actual shapes of the keys 22 differ between the white keys and the black keys.

[0029] The multiple signal generating units 50 are composed of multiple first signal generating units 50a and multiple second signal generating units 50b. The first signal generating units 50a correspond to the first keys 22a, and the second signal generating units 50b correspond to the second keys 22b. That is, for example, of the multiple signal generating units 50 arranged in the X-axis direction, the odd-numbered signal generating units 50 are first signal generating units 50a, and the even-numbered signal generating units 50 are second signal generating units 50b. Therefore, the first signal generating units 50a and the second signal generating units 50b are arranged alternately in the X-axis direction.

[0030] Fig. 8 is a plan view of the first signal generating unit 50a as viewed in the positive direction of the Z axis, and Fig. 9 is a cross-sectional view taken along line aa in Fig. 8. Fig. 10 is a plan view of the second signal generating unit 50b as viewed in the positive direction of the Z axis, and Fig. 11 is a cross-sectional view taken along line bb in Fig. 10.

[0031] 9 and 11, each signal generating unit 50 (first signal generating unit 50a and second signal generating unit 50b) is mounted on a base material 51. The base material 51 is, for example, a hard insulating substrate. Specifically, as illustrated in FIG. 7, the base material 51 is a long plate-like member extending in the X-axis direction across the multiple signal generating units 50. As illustrated in FIGS. 9 and 11, the base material 51 includes a first surface 511 and a second surface 512. The first surface 511 and the second surface 512 are surfaces opposite each other. The first surface 511 is the surface of the base material 51 facing the detection target 60, and the second surface 512 is the surface of the base material 51 facing the support 24. A resistive element R, a capacitive element Ca1, and a capacitive element Ca2 are mounted on the first surface 511 for each signal generating unit 50. The base material 51 may be made of a flexible insulating film.

[0032] A conductive pattern 521 is formed on the first surface 511 of the substrate 51. For example, the conductive pattern 521 is formed by patterning a conductive film that covers the entire first surface 511. The conductive pattern 521 includes an input terminal T1, an output terminal T2, and a ground terminal Tg for each of the multiple signal generating units 50. On the other hand, a conductive pattern 522 is formed on the second surface 512 of the substrate 51. For example, the conductive pattern 522 is formed by patterning a conductive film that covers the entire second surface 512. The configuration of each of the first signal generating unit 50a and the second signal generating unit 50b will be described below.

[0033] [First signal generating unit 50a] 8 and 9, the first signal generating unit 50a includes a first drive coil La1 as the drive coil La in FIG. 3. The first drive coil La1 is composed of a first drive unit A1 and a second drive unit A2. The first drive unit A1 and the second drive unit A2 are arranged in the direction of the Y axis (i.e., the longitudinal direction of each key 22). Specifically, the first drive unit A1 is located in the positive direction of the Y axis when viewed from the second drive unit A2.

[0034] The first driving unit A1 is composed of a laminate of windings A11 and A12. The second driving unit A2 is composed of a laminate of windings A21 and A22. Windings A11 and A21 are included in conductive pattern 521 on first surface 511 and are formed in a spiral shape that spirals clockwise from the inner periphery to the outer periphery as viewed in the positive direction of the Z axis. On the other hand, windings A12 and A22 are included in conductive pattern 522 on second surface 512 and are formed in a spiral shape that spirals counterclockwise from the inner periphery to the outer periphery as viewed in the positive direction of the Z axis. The centers of windings A11 and A12 are mutually conductive via conductive hole Ha11. Similarly, the centers of windings A21 and A22 are mutually conductive via conductive hole Ha12. The conductive holes Ha (Ha11, Ha12, Ha13, Ha14, Ha21, Ha22, Ha23, and Ha24) are through holes formed in the substrate 51.

[0035] The winding portion A11 is connected to the input terminal T1 via the resistive element R, and the winding portion A21 is connected to the output terminal T2. In addition, the capacitive element Ca1 is provided between the resistive element R and the ground terminal Tg, and the capacitive element Ca2 is provided between the output terminal T2 and the ground terminal Tg.

[0036] The first signal generating unit 50a includes wiring 53 within a conductive pattern 521. The winding A12 of the first driving unit A1 is electrically connected to one end of the wiring 53 through a conductive hole Ha13, and the winding A22 of the second driving unit A2 is electrically connected to the other end of the wiring 53 through a conductive hole Ha14. In other words, the winding A12 and the winding A22 are electrically connected via the wiring 53.

[0037] As can be seen from FIG. 8, when a current flows in the first direction α1 through the winding portion A11, a current also flows in the first direction α1 through the winding portion A12. Furthermore, when a current flows in the first direction α1 through the winding portion A11, a current flows in the second direction α2, which is opposite to the first direction α1, through the winding portions A21 and A22. That is, a current flows in the first direction α1 through the first driving portion A1, and a current flows in the second direction α2 through the second driving portion A2. Therefore, when a driving signal W is supplied to the first driving coil La1, magnetic fields in opposite directions are generated in the first driving portion A1 and the second driving portion A2, as illustrated in FIG. 9. Note that the driving signal W is a signal whose signal level periodically inverts, so the first direction α1 and the second direction α2 each periodically invert while maintaining a mutually opposite relationship.

[0038] [Second signal generation unit 50b] 10 and 11, the second signal generating unit 50b includes a second drive coil La2 as the drive coil La in FIG. 3. The second drive coil La2 is composed of a third drive unit A3 and a fourth drive unit A4. The third drive unit A3 and the fourth drive unit A4 are arranged in the direction of the Y axis (i.e., the longitudinal direction of each key 22). Specifically, the third drive unit A3 is located in the positive direction of the Y axis when viewed from the fourth drive unit A4.

[0039] The third drive unit A3 is composed of a laminate of windings A31 and A32. The fourth drive unit A4 is composed of a laminate of windings A41 and A42. Windings A31 and A41 are included in conductive pattern 521 on first surface 511 and are formed in a spiral shape that spirals clockwise from the inner periphery to the outer periphery as viewed in the positive direction of the Z axis. On the other hand, windings A32 and A42 are included in conductive pattern 522 on second surface 512 and are formed in a spiral shape that spirals counterclockwise from the inner periphery to the outer periphery as viewed in the positive direction of the Z axis. The centers of windings A31 and A32 are mutually conductive via conductive hole Ha21. Similarly, the centers of windings A41 and A42 are mutually conductive via conductive hole Ha22.

[0040] Winding portion A31 is connected to input terminal T1 via resistive element R. Capacitive element Ca1 is installed between resistive element R and ground terminal Tg, and capacitive element Ca2 is installed between output terminal T2 and ground terminal Tg. Winding portion A41 is electrically connected to winding portion A32 via conductive hole Ha23, and winding portion A42 is electrically connected to output terminal T2 via conductive hole Ha24.

[0041] As can be seen from FIG. 10, when a current flows in the first direction α1 through winding portion A31, a current also flows in the first direction α1 through winding portion A32. Furthermore, when a current flows in the first direction α1 through winding portion A31, a current also flows in the first direction α1 through winding portions A41 and A42. That is, a current flows in the first direction α1 through both the third drive portion A3 and the fourth drive portion A4. Therefore, when a drive signal W is supplied to the second drive coil La2, magnetic fields are generated in the third drive portion A3 and the fourth drive portion A4 in the same direction, as illustrated in FIG. 11. Because the drive signal W is a signal whose signal level periodically inverts, the first direction α1 and the second direction α2 each periodically invert while maintaining the same directional relationship.

[0042] As described above, the first signal generating unit 50a includes a first driving unit A1 and a second driving unit A2 through which currents flow in opposite directions, and the second signal generating unit 50b includes a third driving unit A3 and a fourth driving unit A4 through which currents flow in the same direction.

[0043] As illustrated in FIG. 7, the multiple detectable portions 60 are composed of multiple first detectable portions 60a and multiple second detectable portions 60b. The first detectable portions 60a correspond to the first key 22a, and the second detectable portions 60b correspond to the second key 22b. Specifically, the first detectable portions 60a are installed on the bottom surface 221 of the first key 22a, and the second detectable portions 60b are installed on the bottom surface 221 of the second key 22b. That is, the odd-numbered detectable portions 60 among the multiple detectable portions 60 are the first detectable portions 60a, and the even-numbered detectable portions 60 among the multiple detectable portions 60 are the second detectable portions 60b. Therefore, the first detectable portions 60a and the second detectable portions 60b are arranged alternately in the X-axis direction. As explained above, each pair of the first signal generating unit 50a and the first detected unit 60a corresponds to the first key 22a, and each pair of the second signal generating unit 50b and the second detected unit 60b corresponds to the second key 22b.

[0044] Fig. 12 is a plan view of the first detected portion 60a as viewed in the positive direction of the Z axis, and Fig. 13 is a cross-sectional view taken along line cc in Fig. 12. Fig. 14 is a plan view of the second detected portion 60b as viewed in the positive direction of the Z axis, and Fig. 15 is a cross-sectional view taken along line dd in Fig. 14.

[0045] As illustrated in FIGS. 13 and 15, each of the detection targets 60 (first detection target 60a and second detection target 60b) is mounted on a base material 61. The base material 61 is, for example, a hard insulating substrate. Specifically, as illustrated in FIG. 7, the base material 61 is a plate-like member individually installed for each key 22. As illustrated in FIGS. 13 and 15, the base material 61 includes a first surface 611 and a second surface 612. The first surface 611 and the second surface 612 are surfaces opposite each other. The first surface 611 is the surface of the base material 61 facing the bottom surface 221 of the key 22, and the second surface 612 is the surface facing the signal generating unit 50. Capacitor elements Cb (Cb1, Cb2) are mounted on the second surface 612. The base material 61 may be made of a flexible insulating film.

[0046] A conductive pattern 621 is formed on a first surface 611 of the substrate 61. For example, the conductive pattern 621 is formed by patterning a conductive film that covers the entire first surface 611. On the other hand, a conductive pattern 622 is formed on a second surface 612 of the substrate 61. For example, the conductive pattern 622 is formed by patterning a conductive film that covers the entire second surface 612. The configurations of the first detected portion 60a and the second detected portion 60b will be described below.

[0047] [First detected portion 60a] 12 and 13, the first detected portion 60a includes a first detection coil Lb1 as the detection coil Lb in FIG. 3. The first detection coil Lb1 is composed of a first portion B1 and a second portion B2. The first portion B1 and the second portion B2 are arranged in the direction of the Y axis (i.e., the longitudinal direction of each key 22). Specifically, the first portion B1 is located in the positive direction of the Y axis when viewed from the second portion B2.

[0048] The first portion B1 is composed of a laminate of winding portions B11 and B12. The second portion B2 is composed of a laminate of winding portions B21 and B22. Winding portions B11 and B21 are included in conductive pattern 621 on the first surface 611 and are formed in a spiral shape that spirals clockwise from the inner periphery to the outer periphery as viewed in the positive direction of the Z axis. On the other hand, winding portions B12 and B22 are included in conductive pattern 622 on the second surface 612 and are formed in a spiral shape that spirals counterclockwise from the inner periphery to the outer periphery as viewed in the positive direction of the Z axis. The centers of winding portions B11 and B12 are mutually conductive via conductive hole Hb11. Similarly, the centers of winding portions B21 and B22 are mutually conductive via conductive hole Hb12. The conductive holes Hb (Hb11, Hb12, Hb21, Hb22) are through holes formed in the substrate 51. A capacitance element Cb1 is disposed between the winding portion B11 and the winding portion B21. The first detection coil Lb1 and the capacitance element Cb1 are connected to each other to form a first resonant circuit 651. The capacitance element Cb1 is an example of a "first capacitance element."

[0049] As can be seen from FIG. 12, when a current flows in the second direction α2 through the winding portion B11, a current also flows in the second direction α2 through the winding portion B12. Furthermore, when a current flows in the second direction α2 through the winding portion B11, a current flows in the first direction α1, which is opposite to the second direction α2, through the winding portions B21 and B22. That is, a current flows in the second direction α2 through the first portion B1 of the first detected portion 60a, and a current flows in the first direction α1 through the second portion B2. Therefore, an induced current is generated in the first detection coil Lb1 due to electromagnetic induction of the magnetic field generated by the first drive coil La1. As a result, as shown in FIG. 13, magnetic fields in opposite directions are generated in the first portion B1 and the second portion B2. However, the induced current generated in the first detection coil Lb1 is very weak.

[0050] [Second detected part 60b] 14 and 15, the second detected portion 60b includes a second detection coil Lb2 as the detection coil Lb in FIG. 3. The second detection coil Lb2 is composed of a third portion B3 and a fourth portion B4. The third portion B3 and the fourth portion B4 are arranged in the direction of the Y axis (i.e., the longitudinal direction of each key 22). Specifically, the third portion B3 is located in the positive direction of the Y axis when viewed from the fourth portion B4.

[0051] The third portion B3 is formed by laminating winding portion B31 and winding portion B32. The fourth portion B4 is formed by laminating winding portion B41 and winding portion B42. Winding portion B31 and winding portion B41 are included in conductive pattern 621 on first surface 611, and winding portion B32 and winding portion B42 are included in conductive pattern 622 on second surface 612. Winding portion B31 and winding portion B42 are formed in a spiral shape that spirals clockwise from the inner periphery to the outer periphery when viewed in the positive direction of the Z axis. On the other hand, winding portion B32 and winding portion B41 are formed in a spiral shape that spirals counterclockwise from the inner periphery to the outer periphery when viewed in the positive direction of the Z axis. The centers of winding portion B31 and winding portion B32 are mutually conductive via conduction hole Hb21. Similarly, the center of winding portion B41 and the center of winding portion B42 are electrically connected to each other via conduction hole Hb22. A capacitance element Cb2 is disposed between winding portion B32 and winding portion B42. The second detection coil Lb2 and capacitance element Cb2 are interconnected to form a second resonant circuit 652. The capacitance element Cb2 is an example of a "second capacitance element."

[0052] As can be seen from FIG. 14, when a current flows in the second direction α2 through winding portion B31, a current also flows in the second direction α2 through winding portion B32. Furthermore, when a current flows in the second direction α2 through winding portion B31, a current also flows in the second direction α2 through winding portions B41 and B42. That is, a current flows in the second direction α2 through both the third portion B3 and the fourth portion B4. Therefore, an induced current is generated in the second detection coil Lb2 due to electromagnetic induction of the magnetic field generated by the second drive coil La2. As a result, as shown in FIG. 15, magnetic fields in the same direction are generated in the third portion B3 and the fourth portion B4. However, the induced current generated in the second detection coil Lb2 is very weak.

[0053] As described above, the first detected portion 60a includes the first portion B1 and the second portion B2 through which current flows in opposite directions, and the second detected portion 60b includes the third portion B3 and the fourth portion B4 through which current flows in the same direction.

[0054] 7, the first drive unit A1 of the first drive coil La1 and the third drive unit A3 of the second drive coil La2 are adjacent to each other in the X-axis direction. The second drive unit A2 of the first drive coil La1 and the fourth drive unit A4 of the second drive coil La2 are adjacent to each other in the X-axis direction. Furthermore, the first portion B1 of the first detector coil Lb1 and the third portion B3 of the second detector coil Lb2 are adjacent to each other in the X-axis direction. The second portion B2 of the first detector coil Lb1 and the fourth portion B4 of the second detector coil Lb2 are adjacent to each other in the X-axis direction.

[0055] Additionally, the first drive unit A1 of the first drive coil La1 and the first portion B1 of the first detector coil Lb1 face each other in the Z-axis direction, the second drive unit A2 of the first drive coil La1 and the second portion B2 of the first detector coil Lb1 face each other in the Z-axis direction, the third drive unit A3 of the second drive coil La2 and the third portion B3 of the second detector coil Lb2 face each other in the Z-axis direction, and the fourth drive unit A4 of the second drive coil La2 and the fourth portion B4 of the second detector coil Lb2 face each other in the Z-axis direction.

[0056] An induced current in the second direction α2 is generated in the first portion B1 of the first detector coil Lb1 due to electromagnetic induction by the first driver A1. An induced current in the first direction α1 is generated in the second portion B2 of the first detector coil Lb1 due to electromagnetic induction by the second driver A2. That is, the first detector coil Lb1 generates a magnetic field in a direction that cancels out the change in the magnetic field of the first driver coil La1. The magnetic field generated by the first detector coil Lb1 changes depending on the distance between the first driver coil La1 and the first detector coil Lb1. Therefore, a detection signal D with an amplitude δ corresponding to the distance between the first driver coil La1 and the first detector coil Lb1 is output from the output terminal T2 of the first signal generator 50a. As can be understood from the above description, the first signal generator 50a generates a detection signal D corresponding to the distance between the first driver coil La1 and the first detector coil Lb1. In the following description, the detection signal D generated by the first signal generator 50a may be specifically referred to as the "first detection signal D1."

[0057] An induced current in the second direction α2 is generated in the third portion B3 of the second detector coil Lb2 due to electromagnetic induction by the third driver A3. An induced current in the second direction α2 is generated in the fourth portion B4 of the second detector coil Lb2 due to electromagnetic induction by the fourth driver A4. That is, a magnetic field is generated by the second detector coil Lb2 in a direction that offsets the change in the magnetic field of the second driver coil La2. The magnetic field generated by the second detector coil Lb2 changes depending on the distance between the second driver coil La2 and the second detector coil Lb2. Therefore, a detection signal D with an amplitude δ corresponding to the distance between the second driver coil La2 and the second detector coil Lb2 is output from the output terminal T2 of the second signal generator 50b. As can be understood from the above description, the second signal generator 50b generates a detection signal D corresponding to the distance between the second driver coil La2 and the second detector coil Lb2. In the following description, the detection signal D generated by the second signal generator 50b may be specifically referred to as the "second detection signal D2."

[0058] FIG. 16 is an explanatory diagram of the operation of the detection system 25. The period during which the detection system 25 operates is divided into a plurality of drive periods G (G1, G2) corresponding to different keys 22. Each drive period G is set to a length sufficiently short compared to the time required for a user to press or release a key. Each drive period G is a period for detecting the position P of one of the plurality of keys 22. That is, the position P of each of the plurality of keys 22 is detected sequentially in a time-division manner for each drive period G, and the operation of detecting the positions P of all keys 22 on the keyboard 21 is repeated. Specifically, the drive circuit 70 selects one key 22 corresponding to each of the plurality of drive periods G, supplies a drive signal W to the signal generation unit 50 corresponding to the selected key 22, and acquires the detection signal D generated by the signal generation unit 50.

[0059] The multiple drive periods G include a first drive period G1 and a second drive period G2. The first drive period G1 is a period for detecting the position P of the first key 22a, and the second drive period G2 is a period for detecting the position P of the second key 22b. The first drive periods G1 and the second drive periods G2 are arranged alternately on the time axis.

[0060] During the first drive period G1, the drive circuit 70 supplies a drive signal W to the first signal generation unit 50a and acquires the first detection signal D1 generated by the first signal generation unit 50a. During the second drive period G2, the drive circuit 70 supplies a drive signal W to the second signal generation unit 50b and acquires the second detection signal D2 generated by the second signal generation unit 50b. In other words, the first signal generation unit 50a and the second signal generation unit 50b are driven in a time-division manner. The drive signal W supplied to the first signal generation unit 50a during the first drive period G1 is an example of a "first drive signal," and the drive signal W supplied to the second signal generation unit 50b during the second drive period G2 is an example of a "second drive signal."

[0061] As described above, the magnetic field generated by the first drive coil La1 generates an induced current in the first detector coil Lb1, generating a first detection signal D1 that corresponds to the distance between the first drive coil La1 and the first detector coil Lb1. Similarly, the magnetic field generated by the second drive coil La2 generates an induced current in the second detector coil Lb2, generating a second detection signal D2 that corresponds to the distance between the second drive coil La2 and the second detector coil Lb2. In other words, the position P of each of the multiple keys 22 (the first key 22a and the second key 22b) can be detected.

[0062] Here, we consider a configuration (hereinafter referred to as the "Comparative Example") in which only pairs of first signal generating units 50a and first detectable units 60a are arranged corresponding to each key 22. In the Comparative Example, magnetic field interference occurs between two keys 22 adjacent to each other in the X-axis direction (hereinafter referred to as "adjacent keys"), resulting in a decrease in the accuracy of detecting the position P of each key 22. To solve this problem, a special configuration is required to reduce magnetic field interference between adjacent keys, such as a configuration in which the resonant frequencies of the signal generating units 50 and the detectable units 60 are different between adjacent keys, or a configuration in which the positions of the signal generating units 50 and the detectable units 60 in the Y-axis direction are different between adjacent keys.

[0063] In contrast to the comparative example, in the first embodiment, currents flow in opposite directions through the first drive unit A1 and second drive unit A2 of the first drive coil La1, while currents flow in the same direction through the third drive unit A3 and fourth drive unit A4 of the second drive coil La2. Furthermore, currents flow in opposite directions through the first portion B1 and second portion B2 of the first detection coil Lb1, while currents flow in the same direction through the third portion B3 and fourth portion B4 of the second detection coil Lb2. This configuration reduces magnetic field interference between adjacent keys, resulting in highly accurate detection of the position P of each key 22. The advantages of the first embodiment are described in detail below.

[0064] FIG. 17 is a graph showing the results of measuring the relationship between the position P of each key 22 and the signal level E of the detection signal D. In FIG. 17, the signal level E was measured under a configuration in which the first signal generating unit 50a, the second signal generating unit 50b, and the detected unit 60 (the first detected unit 60a or the second detected unit 60b) are arranged. The horizontal axis of FIG. 17 corresponds to the distance between the drive coil La and the detection coil Lb. In other words, the value of the position P decreases when a key is pressed. FIG. 18 is an explanatory diagram of each sample (1 to 4) in FIG. 17.

[0065] In Sample 1 and Sample 2, the first detectable portion 60a was moved in the Z-axis direction while facing the first signal generating portion 50a. The second detectable portion 60b was not installed. In Sample 1, the signal level E of the first detection signal D1 generated by the first signal generating portion 50a was measured when the drive signal W was supplied only to the first signal generating portion 50a. On the other hand, in Sample 2, the signal level E of the first detection signal D1 generated by the first signal generating portion 50a was measured when the drive signal W was supplied in parallel to both the first signal generating portion 50a and the second signal generating portion 50b.

[0066] In Samples 3 and 4, the second detectable portion 60b was moved in the Z-axis direction while facing the second signal generating portion 50b. The first detectable portion 60a was not installed. In Sample 3, the signal level E of the second detection signal D2 generated by the second signal generating portion 50b was measured when the drive signal W was supplied only to the second signal generating portion 50b. On the other hand, in Sample 4, the signal level E of the second detection signal D2 generated by the second signal generating portion 50b was measured when the drive signal W was supplied in parallel to both the first signal generating portion 50a and the second signal generating portion 50b.

[0067] The relationship between the position P and the signal level E is substantially the same between Sample 1 and Sample 2. That is, as can be understood from the comparison between Sample 1 and Sample 2, whether or not the second signal generating unit 50b is driven does not affect the generation of the first detection signal D1 by the first signal generating unit 50a.

[0068] Now, let's assume that a magnetic field is generated in the second drive coil La2 by the second signal generation unit 50b. Magnetic fields in the same direction are generated in the third drive unit A3 and the fourth drive unit A4 of the second drive coil La2. The magnetic field of the second drive coil La2 reaches the first detection coil Lb1 of the first detectable portion 60a of the adjacent key 22. Therefore, electromagnetic induction caused by the magnetic field of the second drive coil La2 generates induced currents in the same direction in the first portion B1 and the second portion B2 of the first detection coil Lb1. However, the first portion B1 and the second portion B2 are connected so that currents flow in opposite directions. Therefore, the induced currents cancel each other out between the first portion B1 and the second portion B2. For these reasons, the influence of the magnetic field of the second drive coil La2 on the first detection coil Lb1 is reduced.

[0069] The magnetic field of the second drive coil La2 also reaches the first drive coil La1 of the first signal generating unit 50a, which is adjacent to the second drive coil La2. Therefore, electromagnetic induction caused by the magnetic field of the second drive coil La2 tends to generate induced currents in the same direction in the first drive unit A1 and second drive unit A2 of the first drive coil La1. However, the first drive unit A1 and second drive unit A2 are connected so that currents flow in opposite directions. Therefore, the induced currents cancel each other out between the first drive unit A1 and second drive unit A2. As a result, the influence of the magnetic field of the second drive coil La2 on the first drive coil La1 is reduced.

[0070] For the reasons explained above, as mentioned above, the magnetic field generated by the second drive coil La2 when driven by the second signal generating unit 50b does not affect the generation of the first detection signal D1 using the first drive coil La1 and the first detection coil Lb1.

[0071] Furthermore, the relationship between the position P and the signal level E is substantially the same between Sample 3 and Sample 4. That is, as can be understood from the comparison between Sample 3 and Sample 4, whether or not the first signal generating unit 50a is driven does not affect the generation of the second detection signal D2 by the second signal generating unit 50b.

[0072] Now, let's assume that a magnetic field is generated in the first drive coil La1 by the drive of the first signal generating unit 50a. Opposite magnetic fields are generated in the first drive unit A1 and the second drive unit A2 of the first drive coil La1. The magnetic field of the first drive coil La1 reaches the second detection coil Lb2 of the second detectable portion 60b of the adjacent key 22. Therefore, due to electromagnetic induction caused by the magnetic field of the first drive coil La1, induced currents in opposite directions are generated in the third portion B3 and the fourth portion B4 of the second detection coil Lb2. However, the third portion B3 and the fourth portion B4 are connected so that currents flow in the same direction. Therefore, the induced currents cancel each other out between the third portion B3 and the fourth portion B4. For these reasons, the influence of the magnetic field of the first drive coil La1 on the second detection coil Lb2 is reduced.

[0073] The magnetic field of the first drive coil La1 also reaches the second drive coil La2 of the second signal generating unit 50b of the adjacent key 22. Electromagnetic induction caused by the magnetic field of the first drive coil La1 generates induced currents in opposite directions in the third drive unit A3 and fourth drive unit A4 of the second drive coil La2. However, the third drive unit A3 and fourth drive unit A4 are connected so that currents flow in the same direction. Therefore, the induced currents cancel each other out between the third drive unit A3 and the fourth drive unit A4. This reduces the influence of the first signal generating unit 50a on the second drive coil La2.

[0074] For the reasons explained above, as mentioned above, the magnetic field generated by the first drive coil La1 when the first signal generating unit 50a is driven does not affect the generation of the second detection signal D2 using the second drive coil La2 and the second detection coil Lb2.

[0075] 17, Fig. 19 is a graph showing the results of measuring the relationship between the position P of each key 22 and the signal level E of the detection signal D. Fig. 20 is an explanatory diagram of each sample (5 to 8) in Fig. 19.

[0076] In Samples 5 and 6, the second detectable portion 60b was moved in the Z-axis direction while facing the second signal generating portion 50b. The first detectable portion 60a was not installed. In Sample 5, the signal level E of the first detection signal D1 generated by the first signal generating portion 50a was measured when the drive signal W was supplied only to the first signal generating portion 50a. On the other hand, in Sample 6, the signal level E of the first detection signal D1 generated by the first signal generating portion 50a was measured when the drive signal W was supplied in parallel to both the first signal generating portion 50a and the second signal generating portion 50b.

[0077] In Samples 7 and 8, the first detectable portion 60a was moved in the Z-axis direction while facing the first signal generating portion 50a. The second detectable portion 60b was not installed. In Sample 7, the signal level E of the second detection signal D2 generated by the second signal generating portion 50b was measured when the drive signal W was supplied only to the second signal generating portion 50b. On the other hand, in Sample 8, the signal level E of the second detection signal D2 generated by the second signal generating portion 50b was measured when the drive signal W was supplied in parallel to both the first signal generating portion 50a and the second signal generating portion 50b.

[0078] As can be seen from a comparison between Sample 5 and Sample 6, the position P of the second detectable portion 60b, as well as whether the second signal generating portion 50b is driven, does not affect the generation of the first detection signal D1 by the first signal generating portion 50a. Also, as can be seen from a comparison between Sample 7 and Sample 8, the position P of the first detectable portion 60a, as well as whether the first signal generating portion 50a is driven, does not affect the generation of the second detection signal D2 by the second signal generating portion 50b.

[0079] As described above, according to the first embodiment, the influence of the magnetic field between the set of first drive coil La1 and first detection coil Lb1 (hereinafter referred to as the "first coil set") and the set of second drive coil La2 and second detection coil Lb2 (hereinafter referred to as the "second coil set") is reduced. Therefore, even in a configuration in which first key 22a and second key 22b are close to each other, it is possible to generate detection signal D that accurately reflects the positions P of first key 22a and second key 22b.

[0080] As described above, according to the first embodiment, the influence of the magnetic field between the first coil group and the second coil group is reduced. Therefore, the configuration for varying the resonant frequencies of the signal generating unit 50 and the detectable unit 60 between adjacent keys, or the configuration for varying the positions of the signal generating unit 50 and the detectable unit 60 in the Y-axis direction between adjacent keys, can be omitted in the first embodiment. However, the above configurations may be adopted in the first embodiment. Furthermore, the reduced influence of the magnetic field between the first coil group and the second coil group allows the magnetic fields generated by the first drive coil La1 and the second drive coil La2 to be strengthened compared to the comparative example. Therefore, the position P can be detected over a wide range for each of the first key 22a and the second key 22b.

[0081] B: Second embodiment A second embodiment will be described. Note that, for elements in the following exemplary aspects that have the same functions as those in the first embodiment, the same reference numerals as those in the first embodiment will be used, and detailed descriptions of each will be omitted as appropriate.

[0082] 16, in the first embodiment, each of the multiple signal generating units 50 is driven sequentially for each drive period G. However, as mentioned above, the influence of the magnetic field between the first coil group and the second coil group is reduced, so even if the first coil group and the second coil group operate in parallel with each other, it is possible to measure the position P of each key 22 with high accuracy. Taking the above into consideration, in the second embodiment, the drive signal W is supplied to the first signal generating unit 50a and the drive signal W is supplied to the second signal generating unit 50b in parallel with each other.

[0083] 21 is an explanatory diagram of the operation of the detection system 25 in the second embodiment. The drive circuit 70 in the second embodiment drives, in parallel, the first signal generation unit 50a and the second signal generation unit 50b corresponding to two adjacent keys 22 (the first key 22a and the second key 22b). That is, the drive circuit 70 supplies, in parallel, a drive signal W to the first signal generation unit 50a and a drive signal W to the second signal generation unit 50b during each drive period G. The drive circuit 70 also receives, in parallel, the first detection signal D1 generated by the first signal generation unit 50a and the second detection signal D2 generated by the second signal generation unit 50b during each drive period G.

[0084] The process of identifying the position P of each key 22 in accordance with the signal level E of the detection signal D generated by each signal generating unit 50 is the same as in the first embodiment. The above process is repeated for different pairs of the first signal generating unit 50a and the second signal generating unit 50b to identify the position P of each of the multiple keys 22. Note that the drive signal W supplied to the first signal generating unit 50a during the drive period G is an example of a "first drive signal," and the drive signal W supplied to the second signal generating unit 50b during the drive period G is an example of a "second drive signal."

[0085] The second embodiment also achieves the same effects as the first embodiment. Furthermore, in the second embodiment, the first signal generating unit 50a and the second signal generating unit 50b are driven in parallel. Therefore, compared to the first embodiment in which the first signal generating unit 50a and the second signal generating unit 50b are driven in different driving periods G (G1, G2), the second embodiment has the advantage of making it easier to ensure the length of the driving period G.

[0086] On the other hand, in the first embodiment, the first signal generating unit 50a and the second signal generating unit 50b are driven in different driving periods G (G1, G2). Therefore, compared to the second embodiment in which the first signal generating unit 50a and the second signal generating unit 50b are driven in parallel, the influence of the magnetic field between the first coil set and the second coil set can be further reliably reduced.

[0087] C: Third embodiment In the first embodiment, the position P of the key 22 was identified from the signal level E of the detection signal D using the correlation table F. However, as can be seen from FIG. 17 , the relationship between the position P of the first key 22a and the signal level E of the first detection signal D1 (Sample 1 and Sample 2) may differ from the relationship between the position P of the second key 22b and the signal level E of the second detection signal D2 (Sample 3 and Sample 4). Taking the above circumstances into consideration, in the third embodiment, (1) the relationship between the signal level E of the first detection signal D1 and the position P of the first key 22a identified by the control device 31 (position analysis unit) from the signal level E, and (2) the relationship between the signal level E of the second detection signal D2 and the position P of the second key 22b identified by the control device 31 (position analysis unit) from the signal level E, differ.

[0088] 22 is a schematic diagram of the correlation table F (F1, F2) used by the control device 31 to identify (S2) the position P of each key 22. The storage device 32 of the third embodiment stores a correlation table F1 and a correlation table F2.

[0089] The correlation table F1 is used to identify the position P of the first key 22a from the first detection signal D1 generated by the first signal generating unit 50a. Specifically, the correlation table F1 is a data table in which the position P (P11, P12, ...) of each first key 22a is set for each of a plurality of possible values ​​(E11, E12, ...) of the signal level E of the first detection signal D1.

[0090] On the other hand, the correlation table F2 is used to identify the position P of the second key 22b from the second detection signal D2 generated by the second signal generator 50b. Specifically, the correlation table F2 is a data table in which the position P (P21, P22, ...) of each second key 22b is set for each of a plurality of possible values ​​(E21, E22, ...) of the signal level E of the second detection signal D2.

[0091] The position P corresponding to one numerical value of the signal level E differs between correlation table F1 and correlation table F2. For example, as can be seen from Fig. 17, the signal level E of the first detection signal D1 when the first key 22a is at a specific position P exceeds the signal level E of the second detection signal D2 when the second key 22b is at the same position P. Taking the above difference into consideration, the numerical value of the position P corresponding to a specific signal level E in correlation table F1 exceeds the numerical value of the position P corresponding to the same signal level E in correlation table F2.

[0092] The control device 31 (position analysis unit) uses correlation table F1 to identify the position P of the first key 22a from the signal level E of the first detection signal D1, and uses correlation table F2 to identify the position P of the second key 22b from the signal level E of the second detection signal D2. The configuration and operation other than the identification of the position P are the same as those in the first embodiment.

[0093] The third embodiment also achieves the same effects as the first embodiment. Furthermore, in the third embodiment, the relationship between the signal level E of the first detection signal D1 and the position P of the first key 22a is different from the relationship between the signal level E of the second detection signal D2 and the second key 22b. Therefore, in a situation where the first key 22a and the second key 22b are at the same position P and the signal level E of the first detection signal D1 and the signal level E of the second detection signal D2 are different, the positions P of the first key 22a and the second key 22b can be identified with high accuracy.

[0094] D: Fourth embodiment Fig. 23 is a graph showing the relationship (hereinafter referred to as "position-level characteristics") between the position P of each key 22 and the signal level E of the detection signal D. In Fig. 23, the position-level characteristics of the first key 22a and the position-level characteristics of the second key 22b are shown together.

[0095] Position Pa in Figure 23 is position P of the key 22 when the drive coil La and the detector coil Lb are closest to each other. In other words, position Pa is position P of the key 22 when the key is pressed to the bottom of its allowable displacement range. On the other hand, position Pb in Figure 23 is position P of the key 22 when the drive coil La and the detector coil Lb are furthest apart. In other words, position Pb is position P of the key 22 when it is released. As can be understood from the above explanation, the horizontal axis in Figure 23 can also be expressed as the distance between the drive coil La and the detector coil Lb.

[0096] 23, by adjusting the conditions of the drive coil La and the detection coil Lb, it is possible to match the signal level E at each of positions Pa and Pb between the first key 22a and the second key 22b. The conditions of the drive coil La and the detection coil Lb include, for example, the number of coil turns, wire width, outer size, or radial spacing.

[0097] By configuring the conditions for the first drive coil La1 and the second drive coil La2 to be different, or by configuring the conditions for the first detector coil Lb1 and the second detector coil Lb2 to be different, the signal level E at each of positions Pa and Pb is matched between first key 22a and second key 22b. Specifically, the conditions for drive coil La and detector coil Lb are determined so that the inductance of first drive coil La1 and the inductance of second drive coil La2 are substantially matched, and the inductance of first detector coil Lb1 and the inductance of second detector coil Lb2 are substantially matched.

[0098] However, as can be seen from graph 1 in Fig. 23, simply adjusting the conditions of the drive coil La and the detection coil Lb may result in differences in the position-level characteristics between the first key 22a and the second key 22b in the range between positions Pa and Pb. The fourth embodiment is an embodiment intended to reduce the differences in the position-level characteristics described above.

[0099] 24 is a plan view of the first detected part 60a in the fourth embodiment. The first resonant circuit 651 of the first detected part 60a in the fourth embodiment includes a resistive element Rb1 in addition to the first detection coil Lb1 and capacitive element Cb1 similar to those in the first embodiment. The resistive element Rb1 is an example of a "first resistive element."

[0100] The resistive element Rb1 is a chip resistor connected to the first detection coil Lb1. The resistive element Rb1 is connected in series to the first detection coil Lb1 and the capacitive element Cb1. The resistive element Rb1 is disposed on the second surface 612 of the substrate 61 (see FIG. 13) together with the capacitive element Cb1.

[0101] In the above configuration, the position-level characteristics of the first key 22a change according to the resistance value of the resistor element Rb1. Specifically, the position-level characteristics in the range between positions Pa and Pb change according to the resistance value of the resistor element Rb1. As illustrated by graph 2 in FIG. 23, the resistance value of the resistor element Rb1 is determined so that the position-level characteristics in the range between positions Pa and Pb approach (ideally match) those of the first key 22a and the second key 22b. Specifically, the resistance value of the resistor element Rb1 is lower than the resistance value of the resistance component (DC resistance) associated with the first detection coil Lb1.

[0102] The fourth embodiment also achieves the same effects as the first embodiment. Furthermore, in the fourth embodiment, the resistive element Rb1 is connected to the first detection coil Lb1 of the first detected portion 60a. Therefore, as described above, the position-level characteristics over the entire range between positions Pa and Pb can be made sufficiently close (ideally matched) between the first key 22a and the second key 22b. While the fourth embodiment is based on the first embodiment, the configurations of the second or third embodiment may also be applied to the fourth embodiment.

[0103] In the above description, a configuration in which a resistive element Rb1 is added to the first detected portion 60a has been exemplified, but a configuration in which a resistive element Rb2 is added to the second detected portion 60b is also envisioned, as exemplified in Fig. 25. The resistive element Rb2 is connected in series with the second detection coil Lb2 and the capacitive element Cb2 to form a second resonant circuit 652. The resistive element Rb2 is an example of a "second resistive element."

[0104] The resistive element Rb2 is a chip resistor connected to the second detection coil Lb2 and is disposed on the second surface 612 of the substrate 61 (see FIG. 15 ) together with the capacitive element Cb2. The position-level characteristics of the second key 22b change depending on the resistance value of the resistive element Rb2. Therefore, the resistance value of the resistive element Rb2 is determined so that the position-level characteristics between the first key 22a and the second key 22b in the range between positions Pa and Pb approach (ideally match) each other. For example, the resistance value of the resistive element Rb2 is lower than the resistance value of the resistance component (DC resistance) associated with the second detection coil Lb2. The embodiment of FIG. 25 also achieves the same effects as the fourth embodiment.

[0105] A configuration in which both resistive element Rb1 and resistive element Rb2 are provided is also conceivable. In a configuration in which both resistive element Rb1 and resistive element Rb2 are provided, the resistance value of resistive element Rb1 may differ from the resistance value of resistive element Rb2. In addition, although the above description has been given of an example in which resistive element Rb1 and resistive element Rb2 are chip resistors, the configuration of resistive element Rb1 and resistive element Rb2 is not limited to this example. For example, resistive element Rb1 or resistive element Rb2 may be realized by meandering wiring in which conductive pattern 621 or conductive pattern 622 is meandered.

[0106] E: Modified Example Specific modified embodiments that can be added to each of the above-described embodiments are exemplified below. Multiple embodiments arbitrarily selected from the above-described embodiments and the modified embodiments exemplified below may be combined as appropriate within the scope of not mutually contradicting each other.

[0107] (1) In the above-described embodiments, the configuration for detecting the position P of the key 22 of the keyboard instrument 100 has been exemplified, but the movable member whose position P is detected by the detection system 25 is not limited to the key 22. Specific examples of the movable member are given below.

[0108] [Aspect A] FIG. 26 is a schematic diagram of a configuration in which a detection system 25 is applied to a string-striking mechanism 91 of a keyboard instrument 100. The string-striking mechanism 91 is an action mechanism that strikes strings (not shown) in conjunction with the movement of each key 22 on the keyboard 21, similar to that of an acoustic piano. Specifically, the string-striking mechanism 91 includes a hammer 911 that can strike the strings by rotating, and a transmission mechanism 912 (e.g., a wippen, jack, or repetition lever) for each key 22 that rotates the hammer 911 in conjunction with the movement of the key 22. In the above configuration, the detection system 25 detects the position of the hammer 911. Specifically, a detection target 60 is provided on the hammer 911 (e.g., a hammer shank). Meanwhile, the signal generating unit 50 is provided on a support member 913. The support member 913 is, for example, a structure that supports the string-striking mechanism 91. Note that the detection target 60 may be provided on a member of the string-striking mechanism 91 other than the hammer 911.

[0109] [Aspect B] FIG. 27 is a schematic diagram of a configuration in which the detection system 25 is applied to a pedal mechanism 92 of a keyboard instrument 100. The pedal mechanism 92 includes a pedal 921 operated by the user's foot, a support member 922 that supports the pedal 921, and an elastic body 923 that urges the pedal 921 upward in the vertical direction. In the above configuration, the detection system 25 detects the position of the pedal 921. Specifically, the detected portion 60 is installed on the bottom surface of the pedal 921. Meanwhile, the signal generating unit 50 is installed on the support member 922 so as to face the detected portion 60. Note that the instrument in which the pedal mechanism 92 is used is not limited to the keyboard instrument 100. A pedal mechanism 92 with a similar configuration can also be used in any other instrument, such as a percussion instrument.

[0110] Although Fig. 27 illustrates pedal mechanism 92 for keyboard instrument 100, a pedal mechanism used in an electric musical instrument such as an electric string instrument (for example, an electric guitar) also employs a configuration similar to that shown in Fig. 27. The pedal mechanism used in an electric musical instrument is an effect pedal operated by a user to adjust various sound effects such as distortion or compressor.

[0111] Furthermore, while the above-described embodiments have been described as examples of configurations for detecting each key 22 of the keyboard instrument 100, the objects to be detected by the detection system 25 are not limited to these examples. For example, the detection system 25 may detect controls operated by a user when playing a wind instrument such as a woodwind instrument (e.g., a clarinet or saxophone) or a brass instrument (e.g., a trumpet or trombone).

[0112] As can be understood from the above examples, the objects of detection by the detection system 25 are generally expressed as movable parts that move in response to musical performance manipulations. Movable parts include performance controls such as the keys 22 or pedals 921 that are directly operated by the user, as well as structures such as the hammer 911 that move in conjunction with manipulations of the performance controls. However, the movable parts in this disclosure are not limited to parts that move in response to musical performance manipulations. In other words, the movable parts are generally expressed as parts that can move regardless of the trigger that causes the movement.

[0113] (2) In the above-described embodiments, the drive coil La (La1, La2) is configured in two layers, but a single-layer drive coil La or a three- or more-layer drive coil La is also possible. Similarly, the detection coil Lb (Lb1, Lb2) may be configured in a single layer or three or more layers.

[0114] (3) In each of the above-described embodiments, a drive signal W having a common waveform is supplied to the first signal generating unit 50a and the second signal generating unit 50b. However, the drive signal W (first drive signal) supplied to the first signal generating unit 50a and the drive signal W (second drive signal) supplied to the second signal generating unit 50b may have different conditions such as waveform, period, or amplitude.

[0115] (4) In the above-described embodiments, the first signal generating unit 50a and the second signal generating unit 50b share the same configuration or electrical characteristics. However, the first signal generating unit 50a and the second signal generating unit 50b may have different configurations or electrical characteristics. For example, by differentiating the electrical characteristics, such as the resistance value of the resistor element R, between the first signal generating unit 50a and the second signal generating unit 50b, it is possible to make the relationship between the position P of the first key 22a and the signal level E of the first detection signal D1 closer to the relationship between the position P of the second key 22b and the signal level E of the second detection signal D2. Similarly, the first detected unit 60a and the second detected unit 60b may have different configurations or electrical characteristics.

[0116] (5) In the above-described embodiments, the signal level E of the detection signal D decreases when a key is pressed, but the relationship between the change in the position P of each key 22 and the increase or decrease in the signal level E of the detection signal D is not limited to the above examples. For example, in an embodiment in which the detection target 60 is located between the tip of the key 22 and the balance pin 23, the distance between the drive coil La and the detection coil Lb decreases when the user presses a key. Therefore, the signal level E of the detection signal D increases when the key is pressed.

[0117] (6) In the above-described embodiments, the keyboard instrument 100 is illustrated as having a sound source circuit 34. However, in a configuration in which the keyboard instrument 100 has a sound-producing mechanism such as a string-striking mechanism 91, the sound source circuit 34 may be omitted. The detection system 25 is used to record the performance of the keyboard instrument 100. As can be understood from the above explanation, the musical instruments according to the present disclosure include not only electronic musical instruments having a sound source circuit 34, but also natural musical instruments having a sound-producing mechanism.

[0118] The present disclosure is also specified as an apparatus (operation device) that controls musical tones by outputting operation signals to a sound source circuit 34 or a sound generation mechanism in response to a performance operation. In addition to musical instruments (keyboard instruments 100) equipped with a sound source circuit 34 or a sound generation mechanism as exemplified in the above embodiments, the concept of an operation device also encompasses devices that do not have a sound source circuit 34 or a sound generation mechanism (for example, a MIDI controller or the pedal mechanism 92 described above). In other words, the instrument playing apparatus in the present disclosure is comprehensively expressed as a device that a performer (operator) operates to perform a performance.

[0119] (7) As described above, the functions of the control system 30 according to each of the above embodiments are realized through cooperation between one or more processors constituting the control device 31 and a program stored in the storage device 32. The programs exemplified above can be provided in a form stored on a computer-readable recording medium and installed on a computer. The recording medium is, for example, a non-transitory recording medium, such as an optical recording medium (optical disk) such as a CD-ROM, but also includes any known form of recording medium, such as a semiconductor recording medium or a magnetic recording medium. Note that a non-transitory recording medium includes any recording medium other than a transitory, propagating signal, and does not exclude volatile recording media. Furthermore, in a configuration in which a distribution device distributes a program via a communication network, the recording medium storing the program in the distribution device corresponds to the non-transitory recording medium described above.

[0120] F: Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0121] A detection system according to one aspect (aspect 1) of the present disclosure comprises a first detection coil mounted on a first movable member, a second detection coil mounted on a second movable member, a first drive coil facing the first detection coil and comprising: a first signal generating unit configured to generate a first detection signal in accordance with the distance between the first detection coil and the first drive coil; and a second signal generating unit configured to generate a second detection signal in accordance with the distance between the second detection coil and the second drive coil and comprising: a second drive coil facing the second detection coil; the first drive coil comprising a first drive unit through which current flows in a first direction and a second drive unit through which current flows in a second direction opposite to the first direction; the second drive coil comprising a third drive unit through which current flows in the first direction and a fourth drive unit through which current flows in the first direction; the first detection coil comprising a first portion and a second portion in which induced currents in opposite directions are generated due to electromagnetic induction in the first drive coil; and the second detection coil comprising a third portion and a fourth portion in which induced currents in the same direction are generated due to electromagnetic induction in the second drive coil.

[0122] In the above-described embodiment, a magnetic field generated by the first drive coil generates an induced current in the first detector coil, generating a first detection signal corresponding to the distance between the first drive coil and the first detector coil. Similarly, a magnetic field generated by the second drive coil generates an induced current in the second detector coil, generating a second detection signal corresponding to the distance between the second drive coil and the second detector coil. In other words, the positions of the first movable member and the second movable member can be detected.

[0123] On the other hand, the magnetic field generated by the first drive coil cancels out the induced currents generated by the third drive unit and the fourth drive unit of the second drive coil. Also, the magnetic field generated by the first drive coil cancels out the induced currents generated by the third and fourth portions of the second detector coil. Similarly, the magnetic field generated by the second drive coil cancels out the induced currents generated by the first drive unit and the second drive unit of the first drive coil. Also, the magnetic field generated by the second drive coil cancels out the induced currents generated by the first and second portions of the first detector coil.

[0124] As described above, the influence of the magnetic field between the set of the first drive coil and first detection coil (hereinafter referred to as the "first coil set") and the set of the second drive coil and second detection coil (hereinafter referred to as the "second coil set") is reduced. Therefore, even in a configuration in which the first movable member and the second movable member are close to each other, it is possible to generate first detection signals and second detection signals that accurately reflect the positions of the first movable member and the second movable member, respectively. Furthermore, reducing the influence of the magnetic field between the first coil set and the second coil set makes it possible to strengthen the magnetic fields generated by the first drive coil and the second drive coil. Therefore, it is possible to detect the positions of the first movable member and the second movable member over a wide range.

[0125] A "(first / second) movable member" is a movable member. For example, an operator that moves in response to an operation by a user is an example of a "movable member." Specifically, a member that moves in response to a performance operation by a user is an example of a "movable member." For example, a performance operator (e.g., a key on a keyboard instrument) that is directly operated by a user, as well as a sound-producing mechanism (e.g., a hammer) that moves in conjunction with the performance operator, are examples of a "movable member."

[0126] The "first direction" and the "second direction" are opposite directions. The magnetic field generated by a current in the first direction and the magnetic field generated by a current in the second direction are opposite directions. The first direction and the second direction are not limited to a fixed direction. That is, the first direction and the second direction may be reversed, for example, periodically, while maintaining an opposite relationship to each other.

[0127] In a specific example (Aspect 2) of Aspect 1, the first movable member and the second movable member are adjacent to each other in a specific direction, the first drive unit and the third drive unit are adjacent to each other in the specific direction, the second drive unit and the fourth drive unit are adjacent to each other in the specific direction, the first portion and the third portion are adjacent to each other in the specific direction, and the second portion and the fourth portion are adjacent to each other in the specific direction. In the above aspect, the positions of the first movable member and the second movable member, which are adjacent to each other in a closely spaced state, can be identified with high accuracy.

[0128] A specific example (Aspect 3) of Aspect 1 or Aspect 2 further includes a drive circuit that drives each of the first signal generating unit and the second signal generating unit, and the drive circuit supplies a first drive signal to the first signal generating unit in a first drive period and a second drive signal to the second signal generating unit in a second drive period that is different from the first drive period. In the above aspect, the first signal generating unit and the second signal generating unit are driven in different drive periods. Therefore, compared to an aspect in which the first signal generating unit and the second signal generating unit are driven in parallel, the influence of the magnetic field between the first coil set and the second coil set can be more reliably reduced.

[0129] The "(first / second) drive signal" is a periodic signal that generates a magnetic field in the drive coil. The first drive signal and the second drive signal may or may not be the same. For example, signals with common characteristics such as amplitude or period may be used as the first drive signal and the second drive signal, or the first drive signal and the second drive signal may have different amplitudes.

[0130] A specific example (Aspect 4) of Aspect 1 or Aspect 2 further includes a drive circuit that drives each of the first signal generation unit and the second signal generation unit, and the drive circuit executes supplying a first drive signal to the first signal generation unit and supplying a second drive signal to the second signal generation unit in parallel during a drive period. In the above aspect, the first signal generation unit and the second signal generation unit are driven in parallel. Therefore, compared to an aspect in which the first signal generation unit and the second signal generation unit are driven in different drive periods, this has the advantage of making it easier to ensure time available for driving the first signal generation unit and the second signal generation unit.

[0131] In a specific example (Aspect 5) of any of Aspects 1 to 4, the device further includes a position analysis unit that identifies the position of the first movable member from the signal level of the first detection signal and identifies the position of the second movable member from the signal level of the second detection signal, wherein the relationship between the signal level of the first detection signal and the position of the first movable member is different from the relationship between the signal level of the second detection signal and the position of the second movable member. In the above aspects, the relationship between the signal level of the first detection signal and the position of the first movable member is different from the relationship between the signal level of the second detection signal and the position of the second movable member. Therefore, in a configuration in which the signal level of the first detection signal and the signal level of the second detection signal are different when the first movable member and the second movable member are in the same position, the positions of the first movable member and the second movable member can be identified with high accuracy.

[0132] A detection system according to a specific example (Aspect 6) of any of Aspects 1 to 5 includes a first resonant circuit including the first detection coil and a first capacitive element, and a second resonant circuit including the second detection coil and a second capacitive element. In the above aspects, the first detection coil and the first capacitive element form the first resonant circuit, and the second detection coil and the second capacitive element form the second resonant circuit. Therefore, the positions of the first movable member and the second movable member can be determined with high accuracy.

[0133] In a specific example (Aspect 7) of Aspect 6, the first resonant circuit further includes a first resistor element connected to the first detection coil. The relationship between the position of the first movable member and the signal level of the first detection signal (position-level characteristics) may differ from the relationship between the position of the second movable member and the signal level of the second detection signal (position-level characteristics). By appropriately selecting the resistance value of the first resistor element, it is possible to make the position-level characteristics of the first movable member and the second movable member sufficiently close to each other (ideally, match each other).

[0134] In a specific example (Aspect 8) of Aspect 6 or Aspect 7, the second resonant circuit further includes a second resistive element connected to the second detection coil. The relationship between the position of the first movable member and the signal level of the first detection signal (position-level characteristics) may differ from the relationship between the position of the second movable member and the signal level of the second detection signal (position-level characteristics). By appropriately selecting the resistance value of the second resistive element, it is possible to make the position-level characteristics of the first movable member and the second movable member sufficiently close to each other (ideally, match each other).

[0135] A musical instrument according to one aspect (aspect 9) of the present disclosure includes a first movable member and a second movable member that move in response to a performance operation by a user, a first detection coil provided on the first movable member, a second detection coil provided on the second movable member, a first drive coil facing the first detection coil, and a first signal generation unit that generates a first detection signal according to the distance between the first detection coil and the first drive coil, and a second signal generation unit that includes a second drive coil facing the second detection coil, and generates a second detection signal according to the distance between the second detection coil and the second drive coil. the first drive coil includes a first drive unit in which a current flows in a first direction and a second drive unit in which a current flows in a second direction opposite to the first direction; the second drive coil includes a third drive unit in which a current flows in the first direction and a fourth drive unit in which a current flows in the first direction; the first detection coil includes a first portion and a second portion in which induced currents in opposite directions are generated by electromagnetic induction of the first drive coil; and the second detection coil includes a third portion and a fourth portion in which induced currents in the same direction are generated by electromagnetic induction of the second drive coil. [Explanation of symbols]

[0136] 100...keyboard instrument, 20...keyboard unit, 21...keyboard, 22...key, 22a...first key, 22b...second key, 23...balance pin, 24...support, 25...detection system, 30...control system, 31...control device, 32...storage device, 33...A / D converter, 34...sound source circuit, 40...sound emission system, 50...signal generation unit, 50a...first signal generation unit, 50b...second signal generation unit, 60...detected unit, 60a...first detected unit, 60b...second detected unit, 70...drive circuit, 71...supply circuit, 72...output circuit.

Claims

1. a first detection coil disposed on the first movable member; a second detection coil disposed on the second movable member; a first signal generating unit including a first drive coil facing the first detection coil, the first signal generating unit generating a first detection signal according to a distance between the first detection coil and the first drive coil; a second signal generating unit including a second drive coil facing the second detection coil and generating a second detection signal according to a distance between the second detection coil and the second drive coil; The first drive coil a first drive unit through which a current flows in a first direction; a second driving unit through which a current flows in a second direction opposite to the first direction, The second drive coil a third drive unit through which a current flows in the first direction; a fourth drive unit through which a current flows in the first direction, The first detection coil a first portion and a second portion in which induced currents in opposite directions to each other are generated by electromagnetic induction of the first drive coil; The second detection coil is a third portion and a fourth portion in which induced currents in the same direction are generated by electromagnetic induction of the second drive coil; Detection system.

2. the first movable member and the second movable member are adjacent to each other in a specific direction, the first driving unit and the third driving unit are adjacent to each other in the specific direction, the second driving unit and the fourth driving unit are adjacent to each other in the specific direction, the first portion and the third portion are adjacent to each other in the specific direction, The second portion and the fourth portion are adjacent to each other in the specific direction. The detection system of claim 1 .

3. a drive circuit for driving each of the first signal generating unit and the second signal generating unit; Further comprising: The drive circuit supplying a first drive signal to the first signal generating unit during a first drive period; a second drive signal is supplied to the second signal generating unit during a second drive period different from the first drive period; 3. The detection system of claim 1 or claim 2.

4. a drive circuit for driving each of the first signal generating unit and the second signal generating unit; Further comprising: The drive circuit, during a drive period, The supply of the first drive signal to the first signal generating unit and the supply of the second drive signal to the second signal generating unit are executed in parallel.

3. The detection system of claim 1 or claim 2.

5. a position analysis unit that identifies a position of the first movable member from a signal level of the first detection signal and identifies a position of the second movable member from a signal level of the second detection signal; The relationship between the signal level of the first detection signal and the position of the first movable member is different from the relationship between the signal level of the second detection signal and the position of the second movable member.

3. The detection system of claim 1 or claim 2.

6. a first resonant circuit including the first detection coil and a first capacitance element; a second resonant circuit including the second detection coil and a second capacitance element; The detection system of claim 1 , comprising:

7. The first resonant circuit further includes a first resistive element connected to the first detection coil. The detection system of claim 6.

8. The second resonant circuit further includes a second resistive element connected to the second detection coil.

8. The detection system of claim 6 or 7.

9. a first movable member and a second movable member that move in response to a performance operation by a user; a first detection coil disposed on the first movable member; a second detection coil disposed on the second movable member; a first signal generating unit including a first drive coil facing the first detection coil, the first signal generating unit generating a first detection signal according to a distance between the first detection coil and the first drive coil; a second signal generating unit including a second drive coil facing the second detection coil and generating a second detection signal according to a distance between the second detection coil and the second drive coil; The first drive coil a first drive unit through which a current flows in a first direction; a second driving unit through which a current flows in a second direction opposite to the first direction, The second drive coil a third drive unit through which a current flows in the first direction; a fourth drive unit through which a current flows in the first direction, The first detection coil a first portion and a second portion in which induced currents in opposite directions to each other are generated by electromagnetic induction of the first drive coil; The second detection coil is a third portion and a fourth portion in which induced currents in the same direction are generated by electromagnetic induction of the second drive coil; musical instrument.

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