Detection system and performance operation device

Abstract

To achieve EMC in a system for detecting a displacement of a movable member.SOLUTION: A detection system 20 includes: a control device 21 that generates a first signal r that discontinuously changes in signal level over time; a Π type filter 23 that reduces a high frequency component included in the first signal r to generate a second signal R that continuously changes in signal level over time; and a signal processing unit 22 that generates an output signal corresponding to a position of each of a plurality of keys utilizing the second signal R. The signal processing unit 22 has a to-be-detected unit provided for each of the plurality of keys, and a detection circuit corresponding to each of the plurality of keys. The detection circuit generates, from the second signal R, an output signal in accordance with a position of a key corresponding to the detection circuit among the plurality of keys.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Techniques for detecting the displacement of multiple keys on keyboard instruments such as electronic pianos have been proposed. For example, Patent Document 1 discloses a configuration for detecting the position of each key using a coil (first coil) installed on the frame of the keyboard instrument and a coil (second coil) installed on each key. In this configuration, when a key is pressed and the second coil approaches the first coil, a periodic signal supplied to the first coil changes, generating a detection signal indicating that the key is being pressed. [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] However, in the technology of Patent Document 1, the periodic signal supplied to the first coil is a square wave signal whose signal level changes discontinuously and contains high-frequency components. These high-frequency components can become conductive noise or radiated noise and affect other electronic musical instruments located around the keyboard instrument, potentially violating EMC (Electromagnetic Compatibility).

[0005] In view of the above circumstances, one aspect of the present disclosure aims to achieve EMC in a system for detecting the displacement of a movable member such as a key. [Means for solving the problem]

[0006] In order to solve the above problems, a detection system according to one embodiment of the present disclosure is a detection system that detects the position of each of a plurality of movable members that are displaced in response to playing actions, and includes a control unit that generates a first signal whose signal level changes discontinuously over time, a signal conversion unit that converts the first signal into a second signal whose signal level changes continuously over time, and a signal processing unit that uses the second signal to generate an output signal corresponding to the position of each of the plurality of movable members.

[0007] A performance operation device according to one aspect of the present disclosure comprises a plurality of movable members that are displaced in response to performance actions, a control unit that generates a first signal whose signal level changes discontinuously over time, a signal conversion unit that converts the first signal into a second signal whose signal level changes continuously over time, and a signal processing unit that uses the second signal to generate an output signal corresponding to the position of each of the plurality of movable members.

[0008] An electronic keyboard instrument according to one embodiment of the present disclosure comprises a plurality of keys that shift in response to playing actions, a control unit that generates a first signal whose signal level changes discontinuously over time, a signal conversion unit that converts the first signal into a second signal whose signal level changes continuously over time, a signal processing unit that uses the second signal to generate an output signal corresponding to the position of each of the plurality of keys, and a sound source circuit that generates an acoustic signal in response to the output signal generated by the signal processing unit.

[0009] A detection method according to one aspect of the present disclosure detects the position of each of a plurality of movable members that displace in response to playing actions, by generating a first signal whose signal level changes discontinuously over time, converting the first signal into a second signal whose signal level changes continuously over time, and using the second signal to generate an output signal corresponding to the position of each of the plurality of movable members. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram illustrating the configuration of a keyboard instrument according to an embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram illustrating the configuration of a keyboard instrument. [Figure 3] FIG. 2 is a circuit diagram of the detection system. [Figure 4] FIG. 2 is a circuit diagram of a part to be detected. [Figure 5] FIG. 2 is a circuit diagram of a resonant circuit. [Figure 6] 10 is a timing chart showing timings at which the control device supplies a selection signal. [Figure 7] FIG. 10 is a circuit diagram of a detection system according to a modified example. [Figure 8] FIG. 1 is a schematic diagram illustrating a configuration in which the above detection system is applied to a string-striking mechanism of a keyboard instrument. [Figure 9] FIG. 1 is a schematic diagram illustrating a configuration in which the detection system is applied to a pedal mechanism of a keyboard instrument. [Figure 10] FIG. 10 is a diagram illustrating an example of a partial configuration of a detection system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] A: Embodiment 1 is a block diagram showing an example configuration of a keyboard instrument 100 according to an embodiment of the present disclosure. As shown in FIG. 1, the keyboard instrument 100 is an electronic keyboard instrument having a keyboard 10, a detection system 20, a sound source circuit 30, and a sound emission device 40.

[0012] The keyboard 10 is composed of a plurality of keys 12, including a plurality of white keys and a plurality of black keys. Each of the plurality of keys 12 is a movable member that is displaced in response to a performance action by a user. A performance action is an action by a user to play an instrument, and includes, for example, an action of operating each key 12 (i.e., a performance operation).

[0013] 2 is a block diagram illustrating the specific configuration of the keyboard instrument 100, focusing on one key 12 of the keyboard 10. Each key 12 of the keyboard 10 is supported by a support member 14, with a fulcrum (balance pin) 13 as a fulcrum. The support member 14 is a structure (frame) that supports each element of the keyboard instrument 100. An end 121 of each key 12 is displaced vertically when the user presses and releases the key.

[0014] The detection system 20 detects the position of each key 12. In other words, the detection system 20 detects the playing action (the playing operation on each key 12) by the user. The detection system 20 detects the position Z of the end 121 in the vertical direction for each of the multiple keys 12. The position Z is expressed as the amount of displacement of the end 121 relative to the position of the end 121 in a relaxed state where no load is applied to the key 12.

[0015] 3 is a circuit diagram showing an example of the electrical configuration of the detection system 20. As shown in FIG. 3, the detection system 20 includes a control device 21, a signal processing unit 22, a Π-type filter 23, and a rectifier 24.

[0016] The control device 21 is composed of one or more processors that control each element of the keyboard instrument 100. For example, the control device 21 is composed of one or more types of processors, such as a CPU (Central Processing Unit), an SPU (Sound Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit).

[0017] 2, the control device 21 is connected to the storage device 32 and the tone generator circuit 34 via a bus, and together with these constitutes a computer system. In this embodiment, the control device 21 may realize the function of the tone generator circuit 34 by executing a program stored in the storage device 32. The control device 21 is an example of a "control unit."

[0018] The storage device 32 is one or more memories that store programs executed by the control device 21 and data used by the control device 21. The storage device 32 is configured with a known storage medium such as a magnetic recording medium or a semiconductor recording 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 is detachable from the keyboard instrument 100, or an external storage medium (such as online storage) that can communicate with the keyboard instrument 100.

[0019] The control device 21 outputs a first signal r to the Π-type filter 23. The first signal r is a voltage signal whose signal level fluctuates discontinuously. For example, the first signal r is a square wave signal whose signal level periodically changes from one of high level and low level to the other. The first signal r can also be expressed as a digital signal whose signal level changes in a binary manner.

[0020] The Π filter 23 is a low-pass filter that converts a first signal r into a second signal R. The Π filter 23 is an example of a "signal conversion unit." As shown in FIG. 3, the Π filter 23 is provided on a wiring L that connects the multiple analog demultiplexers 221 and the control device 21. The second signal R generated by the Π filter 23 is supplied to the wiring L. The second signal R supplied to the wiring L is supplied in parallel to the multiple analog demultiplexers 221.

[0021] The wiring L extends across the multiple keys 12 (i.e., from one end of the keyboard 10 to the other). Therefore, when the first signal r is supplied to the wiring L, electromagnetic noise due to electromagnetic waves radiated from the wiring L becomes apparent. Therefore, the Π-type filter 23 of this embodiment reduces frequency components higher than the cutoff frequency of the first signal r acquired from the control device 21 while maintaining frequency components lower than the cutoff frequency. Specifically, the second signal R is an analog signal whose signal level changes continuously. For example, the second signal R is a current signal or voltage signal with a sine wave or a waveform similar thereto. As a result of the second signal R with reduced high-frequency components being supplied to the wiring L as described above, radiation of high-frequency components as noise from the wiring L is suppressed. This suppresses the noise radiated from the wiring L from affecting surrounding electronic devices, improving EMC (electromagnetic compatibility).

[0022] 3, the signal processing unit 22 has a plurality (M) of analog demultiplexers 221 and a plurality (M) of analog multiplexers 222 (M is a natural number of 2 or more). In this embodiment, a plurality (N) of resonant circuits 60 are connected to each of the plurality of analog demultiplexers 221 (N is a natural number of 2 or more). For example, in a configuration in which the keyboard 10 includes 88 keys 12, 11 (N=11) of resonant circuits 60 are connected to each of the eight (M=8) analog demultiplexers 221.

[0023] Each analog demultiplexer 221 is a distributor that distributes the second signal R to each of the multiple resonant circuits 60. Specifically, each analog demultiplexer 221 supplies the second signal R to each of the N resonant circuits 60 in a time-division manner. Fig. 6 is a timing chart showing the selection signals S1 and S2 that the control device 21 supplies to the analog demultiplexer 221 and the analog multiplexer 222.

[0024] The selection signal S1 is a signal that sequentially designates one of the M analog demultiplexers 221 and one of the M analog multiplexers 222. The control device 21 selects, in parallel, the m-th (m=1 to M) analog demultiplexer 221 and the m-th analog multiplexer 222. The selection signal S2 is a signal that sequentially selects one of the N resonant circuits 60 corresponding to each analog demultiplexer 221.

[0025] The control device 21 sequentially outputs a selection signal S1 to the M analog demultiplexers 221, thereby selecting each analog demultiplexer 221 in turn for each selection period U. The selection period U is a period during which the control device 21 selects the m-th analog demultiplexer 221 and the m-th analog multiplexer 222.

[0026] The analog demultiplexer 221 supplies a second signal R to each of the N resonant circuits 60 in a time-division manner based on a selection signal S2 during a selection period U selected by the control device 21. The analog multiplexer 222 receives an output signal d from each of the N resonant circuits 60 in a time-division manner based on the selection signal S2 during a selection period U selected by the control device 21. That is, an operation in which the mth analog demultiplexer 221 outputs the second signal R to the nth (n=1 to N) resonant circuit 60 out of the N resonant circuits 60 and an operation in which the mth analog multiplexer 222 receives the output signal d from the nth resonant circuit 60 are executed in parallel. Note that the period of the second signal R is sufficiently shorter than the time length of the period in which the analog demultiplexer 221 selects one resonant circuit 60.

[0027] 2, the signal processing unit 22 has a detection target unit 50 and a resonant circuit 60. The detection target unit 50 and the resonant circuit 60 are provided for each key 12.

[0028] 2, the detected part 50 is installed on the key 12. Specifically, the detected part 50 is installed on the bottom surface 122 (hereinafter referred to as the "installation surface") of the key 12. The detected part 50 has a first coil 51.

[0029] 4 is a circuit diagram showing an example of the electrical configuration of the detected portion 50. The detected portion 50 forms a resonant circuit including a first coil 51 and a capacitive element 52. Both ends of the first coil 51 are connected to both ends of the capacitive element 52. The resonant frequency of the detected portion 50 and the resonant frequency of the resonant circuit 60 are typically the same, but the resonant frequency of the detected portion 50 and the resonant frequency of the resonant circuit 60 may differ for each key 12 or each octave.

[0030] 2 are installed on the support member 14 along the direction in which the keys 12 are arranged. Each of the resonant circuits 60 has a second coil 61. The resonant circuit 60 is an example of a "detection circuit."

[0031] The first coil 51 and the second coil 61 face each other with a vertical gap between them. The distance between the detected part 50 and the resonant circuit 60 (the distance between the first coil 51 and the second coil 61) varies depending on the position Z of the end 121 of the key 12.

[0032] 5 is a circuit diagram showing an example of the electrical configuration of a resonant circuit 60. The resonant circuit 60 has an input terminal T1, an output terminal T2, a second coil 61, a capacitance element 62, and a capacitance element 63. The second coil 61 is connected between the input terminal T1 and the output terminal T2. The capacitance element 62 is connected between the input terminal T1 and a ground line. The capacitance element 63 is connected between the output terminal T2 and a ground line.

[0033] As shown in FIG. 5 , the second signal R is supplied to the input terminal T1 of the resonant circuit 60. The frequencies of the second signal R and the first signal r are approximately equal to the resonant frequencies of the resonant circuit 60 and the detected part 50. A magnetic field is generated in the second coil 61 when a current corresponding to the second signal R is supplied to the second coil 61. An induced current is generated in the first coil 51 due to electromagnetic induction caused by the magnetic field generated in the second coil 61. Therefore, a magnetic field is generated in the first coil 51 in a direction that cancels out the change in the magnetic field of the second coil 61. The frequencies of the first signal r and the second signal R may be different from the resonant frequencies of the resonant circuit 60 and the detected part.

[0034] The magnetic field generated in the first coil 51 changes depending on the distance between the first coil 51 and the second coil 61. Therefore, an output signal d with an amplitude δ corresponding to the distance between the first coil 51 and the second coil 61 is output from the output terminal T2 of the resonant circuit 60. In other words, the output signal d is a periodic signal whose signal level fluctuates with the same period as the second signal R.

[0035] The analog multiplexer 222 is a selector that selects one of the multiple resonant circuits 60 from which the second signal R is to be acquired. The analog multiplexer 222 acquires the output signal d from each resonant circuit 60 in a time-division manner based on the selection signal S2 during the selection period U selected by the control device 21. As can be understood from the above explanation, the signal processing unit 22 in FIG. 3 generates, for each of the multiple keys 12, the output signal d having a signal level that corresponds to the distance between the first coil 51 and second coil 61 corresponding to that key 12.

[0036] The rectifier 24 is connected to the control device 21 and a plurality of analog multiplexers 222. The rectifier 24 converts the output signal d output in a time-division manner from the analog multiplexer 222 into a DC voltage having a voltage value corresponding to the amplitude δ, and outputs the converted DC voltage to the control device 21. The rectifier 24 is formed of, for example, a diode. Note that the method by which the rectifier 24 rectifies the output signal d is not particularly limited, and any method may be used, such as half-wave rectification or full-wave rectification.

[0037] The control device 21 converts the DC voltage obtained from the rectifier 24 from analog to digital and identifies the position Z of each key by analyzing the converted signal. The control device 21 instructs the tone generator circuit 34 to generate a musical tone corresponding to the position Z of the key 12.

[0038] The sound source circuit 34 generates an audio signal V according to the result of detection by the detection system 20. The audio signal V is a signal representing a musical tone of a pitch corresponding to the key 12 operated by the user. Specifically, the sound source circuit 34 generates an audio signal V representing a musical tone instructed by the control device 21. That is, the sound source circuit 34 generates an audio signal V according to the change in position Z of each key over time. For example, the volume of the audio signal V is controlled according to the speed of change in position Z.

[0039] The sound emitting device 40 emits a sound represented by the sound signal V. The sound emitting device 40 receives the sound signal V from the sound source circuit 34 and emits a musical sound corresponding to the performance action (depressing or releasing each key 12) by the user. For example, a speaker or headphones is used as the sound emitting device 40.

[0040] As described above, in this embodiment, the first signal r, whose signal level changes discontinuously over time, is converted by the Π filter 23 into the second signal R, whose signal level changes continuously over time. That is, the high-frequency components of the first signal r are reduced by the Π filter 23 to generate the second signal R. This prevents the high-frequency components from acting as noise and affecting surrounding electronic devices, improving EMC (electromagnetic compatibility).

[0041] In addition, in this embodiment, the analog demultiplexer 221 distributes the second signal R to each of the multiple resonant circuits 60, so the processing load on the control device 21 is reduced compared to a configuration in which the second signal R is supplied in parallel to the multiple resonant circuits 60.

[0042] Furthermore, in this embodiment, a Π-type filter 23 is used as a filter that converts the first signal r into the second signal R, which reduces the manufacturing cost of the detection system 20 and improves the ease and versatility of configuring the system.

[0043] B: Modified example Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and various modifications may be made. Specific modifications that can be made to the above-described embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples may be combined as appropriate within the scope of not mutually contradicting each other.

[0044] (1) In the above embodiment, the analog demultiplexer 221 and the analog multiplexer 222 are provided as separate circuits, but the analog demultiplexer 221 and the analog multiplexer 222 may be integrated into one unit. Specific embodiments of the detection system 20 will be described below.

[0045] 7 is a circuit diagram showing an example of the electrical configuration of a detection system 20 in a modified example. The detection system 20 includes a plurality of (M) input / output units 223. Each of the M input / output units 223 is an electronic circuit in which an analog demultiplexer 221 and an analog multiplexer 222 are integrally configured. Each input / output unit 223 supplies a second signal R to each of the N resonant circuits 60 in a time-division manner, and acquires an output signal d from each of the N resonant circuits 60 in a time-division manner. Note that in FIG. 7, the same components as those in the above-described embodiment are denoted by the same reference numerals, and their description will be omitted.

[0046] (2) In the above embodiment, a configuration for detecting the displacement of the key 12 of the keyboard instrument 100 was exemplified, but the movable member whose displacement is detected by the detection system 20 is not limited to the key 12. Specific examples of movable members are given below.

[0047] [Aspect A] FIG. 8 is a schematic diagram of a configuration in which the detection system 20 is applied to a string-striking mechanism 91 of a keyboard instrument 100. The string-striking mechanism 91 is an action mechanism that strikes strings (not shown) in response to the displacement of each key 12 on the keyboard 10, similar to that of a piano, a natural musical instrument. 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, repetition lever, etc.) for each key 12 that rotates the hammer 911 in response to the displacement of the key 12. In the above configuration, the detection system 20 detects the displacement of the hammer 911. Specifically, a detection target 50 is mounted on the hammer 911 (e.g., a hammer shank). For example, a wiring board 54 constituting the detection target 50 is fixed to the hammer 911 by a fixing member 71, which is a magnetic material. Meanwhile, the resonant circuit 60 is mounted on a support member 913. The support member 913 is, for example, a structure that supports the string-striking mechanism 91. In the present disclosure, the detected part 50 may be provided on a member other than the hammer 911 of the string-striking mechanism 91.

[0048] [Aspect B] FIG. 9 is a schematic diagram illustrating a configuration in which the detection system 20 is applied to a pedal mechanism 92 of a keyboard instrument 100. The pedal mechanism 92 includes a pedal 921 operated by a user's foot, a support member 922 that supports the pedal 921, and an elastic body 923 that biases the pedal 921 upward in the vertical direction. In the above configuration, the detection system 20 detects the displacement of the pedal 921. Specifically, the detection target 50 is installed on the bottom surface of the pedal 921. That is, the wiring board 54 that constitutes the detection target 50 is fixed to the pedal 921 by a fixing member 71 that is a magnetic material. Meanwhile, the resonant circuit 60 is installed on the support member 922 so as to face the detection target 50. Note that in the present disclosure, the instrument in which the pedal mechanism 92 is used is not limited to the keyboard instrument 100. A pedal mechanism 92 having a similar configuration can also be used in any other instrument, such as a percussion instrument.

[0049] As can be understood from the above examples, the object of detection by the detection system 20 is generally expressed as a movable member that displaces in response to a performance action. The movable member includes performance controls such as the keys 12 or pedals 921 that are directly operated by the user, as well as structures such as the hammer 911 that displace in response to the operation of the performance controls. However, the movable member in this disclosure is not limited to a member that displaces in response to a performance action. In other words, the movable member is generally expressed as a member that can be displaced regardless of the trigger that causes the displacement.

[0050] (3) In the above embodiment, the keyboard instrument 100 is provided with the tone generator circuit 34. However, in a configuration where the keyboard instrument 100 is provided with a sound generating mechanism such as a string striking mechanism 91, the tone generator circuit 34 may be omitted. The detection system 20 is used to record the performance of the keyboard instrument 100.

[0051] As can be understood from the above explanation, the present disclosure can also be specified as an apparatus (musical performance operation apparatus) that controls musical tones by outputting operation signals to a sound source circuit 34 or a sound generation mechanism in response to performance actions. The concept of an instrument playing apparatus encompasses not only musical instruments (keyboard instruments 100) equipped with a sound source circuit 34 or a sound generation mechanism as exemplified in the above embodiments, but also devices that do not have a sound source circuit 34 or a sound generation mechanism (e.g., a MIDI controller or the pedal mechanism 92 described above). In other words, the musical performance operation apparatus in the present disclosure is comprehensively expressed as a device that a performer (operator) operates to perform a performance.

[0052] (4) In the above embodiment, each of the plurality of analog demultiplexers 221 is alternatively selected, but two or more of the plurality of analog demultiplexers 221 may be selected in parallel.

[0053] 10 is a partial configuration diagram of a detection system 20 in a modified example. A selection signal S1a is supplied from the control device 21 to each of the odd-numbered analog demultiplexers 221 among the multiple analog demultiplexers 221. On the other hand, a selection signal S1b is supplied to each of the even-numbered analog demultiplexers 221 among the multiple analog demultiplexers 221. The selection signals S1a and S1b are signals that change from one of high level and low level to the other for each selection period U. The selection signals S1a and S1b are signals of opposite phases to each other. For example, the selection signal S1b is generated by inverting the level of the selection signal S1a using an inverter circuit 70.

[0054] During the selection period U in which the selection signal S1a is set to high level, a plurality of odd-numbered (M / 2) analog demultiplexers 221 are selected in parallel. On the other hand, during the selection period U in which the selection signal S1b is set to high level, a plurality of even-numbered (M / 2) analog demultiplexers 221 are selected in parallel. The operation of each selected analog demultiplexer 221 distributing the second signal R to a plurality of resonant circuits 60 in a time-division manner is the same as in the above-described form.

[0055] Although the above description has illustrated the configuration and operation of the multiple analog demultiplexers 221, the same configuration and operation are also adopted for the multiple analog multiplexers 222. Specifically, a selection signal S1a is supplied to each odd-numbered analog multiplexer 222, and a selection signal S1b is supplied to each even-numbered analog demultiplexer 221.

[0056] (5) In the above-described embodiment, the Π filter 23 attenuates the high-frequency components of the first signal r output from the control device 21. However, the configuration for attenuating the high-frequency components of the first signal r is not limited to the Π filter 23, and a low-pass filter of any configuration may be used as the signal conversion unit for converting the first signal r into the second signal R. Examples of low-pass filters used in processing the first signal r include multi-order low-pass filters and active filters, and for example, n-type filters, T-type filters, etc. are adopted.

[0057] (6) In the above-described embodiment, the signal output from the control device 21 is output to the signal processing unit 22 via the wiring L. Any transmission method may be used when the control device 21 outputs a signal to the signal processing unit 22. For example, a differential transmission method may be used, which transmits two systems of signals in opposite phases. The differential transmission method is, for example, LVDS (Low Voltage Differential Signaling).

[0058] (7) In the above embodiment, the control device 21 outputs the first signal r. However, the signal source of the first signal r does not have to be the control device 21. If the signal source outputs the second signal R having a sine wave or a waveform similar thereto, the Π-type filter 23 may be omitted as necessary.

[0059] (8) In the above embodiment, a configuration for detecting the displacement of the key 12 is exemplified. However, the present disclosure may be applied to a technology for detecting the displacement of other movable members, such as pedals, and the application of the present disclosure is not particularly limited.

[0060] (9) In the above embodiment, a configuration has been exemplified in which the distance between the second coil 61 and the detectable portion 50 changes in response to a playing motion, but instead of the above configuration, a configuration is also envisioned in which the area over which the second coil 61 and the detectable portion 50 face each other (hereinafter referred to as the "facing area") changes in response to a playing motion. In other words, in the present disclosure, it is sufficient that the distance or the facing area between the second coil 61 and the detectable portion 50 changes in response to a playing motion.

[0061] C: Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0062] A detection system according to one aspect (aspect 1) of the present disclosure is a detection system for detecting the position of each of a plurality of movable members that are displaced in response to a musical performance, and includes: a control unit that generates a first signal whose signal level changes discontinuously over time; a signal conversion unit that converts the first signal into a second signal whose signal level changes continuously over time; and a signal processing unit that uses the second signal to generate an output signal corresponding to the position of each of the plurality of movable members. With this configuration, the first signal whose signal level changes discontinuously over time is converted by the signal conversion unit into the second signal whose signal level changes continuously over time. That is, the second signal is generated by reducing the high-frequency components of the first signal. This prevents the high-frequency components from acting as noise and affecting surrounding electronic devices, improving EMC (electromagnetic compatibility).

[0063] In a specific example (Aspect 2) of Aspect 1, the signal processing unit includes a detected portion provided on each of the plurality of movable members, and a plurality of detection circuits that generate the output signal from the second signal.

[0064] In a specific example (Aspect 3) of Aspect 2, the detection circuit has a coil facing the detected part, and the signal processing unit changes the second signal depending on the distance between the detected part and the coil. According to the above aspect, the second signal changes depending on the distance between the movable member and the coil. In other words, the second signal changes depending on the amount of displacement of the movable member, so that whether or not a key on the keyboard has been pressed can be detected.

[0065] In a specific example (Aspect 4) of Aspect 2 or Aspect 3, the signal processing unit further includes a distributor that distributes the second signal to each of the plurality of detection circuits. In the above aspect, since the second signal is distributed to each of the plurality of detection circuits, the processing load on the control unit is reduced compared to a configuration in which the second signal is supplied in parallel to the plurality of detection circuits.

[0066] In a specific example (Aspect 5) of Aspect 4, the distributor is an analog demultiplexer.

[0067] In a specific example (aspect 6) of any one of aspects 2 to 5, the signal processing unit further includes a selector that selects, from among the plurality of detection circuits, a detection circuit from which the output signal is to be acquired.

[0068] In a specific example (Aspect 7) of Aspect 6, the selector is an analog multiplexer.

[0069] In a specific example (Aspect 8) of Aspect 7, the signal conversion unit is a Π filter. According to this aspect, by employing a Π filter as the signal conversion unit, the design cost of the detection system is reduced and the ease and versatility of configuring the system are improved.

[0070] In a specific example (Aspect 9) of any one of Aspects 1 to 8, the first signal is a square wave signal, and the second signal is a signal having a waveform similar to a sine wave.

[0071] A performance operation device according to one aspect (aspect 10) of the present disclosure comprises a plurality of movable members that displace in response to performance actions, a control unit that generates a first signal whose signal level changes discontinuously over time, a signal conversion unit that converts the first signal into a second signal whose signal level changes continuously over time, and a signal processing unit that uses the second signal to generate an output signal corresponding to the position of each of the plurality of movable members.

[0072] An electronic keyboard instrument according to one aspect (aspect 11) of the present disclosure comprises a plurality of keys that move in response to playing actions, a control unit that generates a first signal whose signal level changes discontinuously over time, a signal conversion unit that converts the first signal into a second signal whose signal level changes continuously over time, a signal processing unit that uses the second signal to generate an output signal corresponding to the position of each of the plurality of keys, and a sound source circuit that generates an acoustic signal in response to the output signal generated by the signal processing unit.

[0073] A detection method according to one aspect (aspect 12) of the present disclosure detects the position of each of a plurality of movable members that displace in response to playing actions, by generating a first signal whose signal level changes discontinuously over time, converting the first signal into a second signal whose signal level changes continuously over time, and using the second signal to generate an output signal corresponding to the position of each of the plurality of movable members. [Explanation of symbols]

[0074] 100...keyboard instrument (performance operation device), 10...keyboard, 12...key, 20...detection system, 21...control device, 22...signal processing unit, 23...Π-type filter, 24...rectifier, 32...memory device, 34...sound source circuit, 40...sound emission device, 50...detected part, 51...first coil, 52...capacitive element, 60...resonant circuit, 61...second coil, 62, 63...capacitive elements, 71...fixing member, 91...string striking mechanism, 92...pedal mechanism, 911...hammer, 912...transmission mechanism, 913...support member, 921...pedal, 922...support member, 923...elastic body.

Claims

1. A detection system for detecting the position of each of a plurality of movable members that are displaced in response to a performance action, comprising: a control unit that generates a first signal whose signal level changes discontinuously over time; a signal conversion unit that generates a second signal whose signal level changes continuously over time by reducing high frequency components included in the first signal; a signal processing unit that uses the second signal to generate an output signal corresponding to each position of the plurality of movable members, The signal processing unit a detection target portion provided on each of the plurality of movable members; a detection circuit corresponding to each of the plurality of movable members; The detection circuit generates the output signal corresponding to the distance between the detection circuit and the detection target portion of the movable member corresponding to the detection circuit among the plurality of movable members, from the second signal. Detection system.

2. The detected part includes a first resonant circuit having a first coil and a first capacitance element. The detection system of claim 1 .

3. The detection circuit includes a second resonant circuit including a second coil facing the first coil and a second capacitive element. The detection system of claim 2.

4. a plurality of movable members that are displaced in response to playing actions; a control unit that generates a first signal whose signal level changes discontinuously over time; a signal conversion unit that generates a second signal whose signal level changes continuously over time by reducing high frequency components included in the first signal; a signal processing unit that uses the second signal to generate an output signal corresponding to each position of the plurality of movable members, a detection target portion provided on each of the plurality of movable members; a detection circuit corresponding to each of the plurality of movable members; The detection circuit generates the output signal corresponding to the distance between the detection circuit and the detection target portion of the movable member corresponding to the detection circuit among the plurality of movable members, from the second signal. Performance operation device.

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