JP2782949B2 - Keyboard instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a single-string keyboard musical instrument, and based on the vibration state at the time of striking a string, vibrating state of a virtual string having substantially the same pitch as that of the string. Calculates and stores the sound of the single-string keyboard instrument by playing the sound of the virtual string having substantially the same pitch as the strung string that was struck, along with the striking sound during the performance, based on the memory. It is to improve.

<Conventional technology> Conventionally, as a keyboard instrument of this kind, each string has one string.
A monochord piano (or a two-string piano) in which only books (or two) are stretched has been known. That is, unlike a normal three-string piano, only one (or two) strings are stretched on the frame for each key.

<Problems to be Solved by the Invention> However, in such a conventional mono-cord piano, the tone is inferior to that of a normal three-string piano,
There was a problem that the volume was low. In other words, the rich sound of a normal piano is due to the fact that the strings
This is because there are four (rarely four), each of which has a slightly different pitch, spectral characteristic, attenuation, and the like. On the contrary,
In a piano having one (or two) strings, tone quality and the like are inferior even if the tension per string is the same as that of a three-string.

Therefore, the present invention is excellent in timbre by reading out a partial sound corresponding to the stringing sound from the storage means and producing it.
It is an object of the present invention to provide a single-string keyboard instrument with an increased volume.

<Means for Solving the Problems> The present invention relates to a keyboard instrument in which one or two strings are stretched corresponding to a plurality of keys, respectively, as illustrated in FIG. A storage means for detecting a vibration state of the stretched string and calculating a vibration state of the virtual string having substantially the same pitch as the stretched string based on at least a spectral characteristic indicating the detected vibration state; A key detecting means 200 for detecting a pressed key during a performance; and a selecting means 300 for selecting a vibration state of a virtual string having substantially the same pitch as the stretched string corresponding to the pressed key from the storage means 100. And a sounding means 400 for converting the selected vibration state into sound and outputting the sound.

<Operation> In the keyboard musical instrument according to the present invention, striking a strung string produces a sound corresponding to the string.

The storage means 100 calculates and stores the vibration state of the virtual string having substantially the same pitch as the stretched string based on the spectral characteristics indicating the vibration state of the stretched string.

When the key detecting means 200 detects the pressed key during the performance, the selecting means 300 selects the vibration state of the virtual string having substantially the same pitch as the strung string struck from the storage means 100.

Then, the sounding means 400 converts the vibration state of the virtual string into sound and sounds it.

As a result, the sound produced by striking the string and the sounding means 400
And the sound by the
The volume is improved together, and a tone and volume equal to or higher than that of a three-string piano can be obtained.

<Example> Hereinafter, an example of a keyboard instrument according to the present invention will be described with reference to the drawings.

2 to 6 are views for explaining an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic overall configuration of a keyboard instrument according to one embodiment of the present invention.

In this figure, reference numeral 21 denotes a frame of a vertical piano, on which a single string 23 for one key 22 is stretched by a tuning pin 24, a hitch pin or the like.

Reference numeral 25 denotes a soundboard disposed on the back side of the frame 21, and reference numeral 26 denotes a piece fixed to the soundboard 25. This frame 21
Since the number of stretched strings 23 is small (usually three for each key), the acting tension is greatly reduced as a whole, and a small and lightweight one is used.

Other components and components are the same as those of a conventional three-string vertical piano.

For example, an action 27 is provided for each key 22, and the single string 23 is hit and sounded by a hammer 28 of the action 27.

And a piezoelectric element for detecting the vibration state of these strings 23
30 is attached to the string receiving mountain at the upper part of the frame 21 (may be a piece). The piezoelectric element 30 includes all the strings 23 (for example,
(Corresponding to 88 strings), and are disposed in a direction substantially orthogonal to the strings 23.

The piezoelectric element 30 may be any element that picks up the vibration of the string 23, and may be constituted by another mechanical-electrical conversion element.

Further, a reflection type optical sensor 32 is provided opposite to the opening of the catcher 31 that rotates together with the hammer 28, and the optical sensor 32 is provided with a striking speed of the hammer 28 (strictly speaking, a displacement from the catcher 31). Amount).

Further, a key sensor 34 as key detecting means for detecting the pressed key 22 is provided on a keyboard reed 33 disposed below each key 22. These key sensors 34 are constituted by reflected light type optical sensors.

An actuator 35 that is electromagnetically driven to vibrate the soundboard 25 is provided at a predetermined position on the back surface of the soundboard 25. Reference numeral 36 denotes an external speaker built in the piano body, which generates a sound by a drive circuit described later.
The actuator 35 and the external speaker 36 constitute sound generating means.

Further, a mode changeover switch 37 is provided on the lower surface of the arm, and switches the operation mode of an electronic control circuit 38 mainly composed of a microprocessor described later. For example, switching between a recording mode for detecting and recording the vibration state of the string 23, a data processing mode for calculating the vibration state of the virtual string from the vibration state of the string 23, and a performance mode for performing in response to key depression, and
Switches the output.

Here, in this vertical piano, the vibration state of the string 23 is detected, and the vibration state of the virtual string is calculated based on the line spectrum indicating the vibration state. It has a configuration in which sound can be generated via the actuator 35 or the external speaker 36 within a time (5 msec).

That is, the vibration of the string 23 struck by the hammer 28 that rotates in response to the key depression is detected by the piezoelectric element 30, and the string vibration signal is output by the high cut filter 41 to, for example, 8,000.
High frequency components above [Hz] are gradually cut off as noise.

The string vibration signal from which the noise has been removed is input to the input / output unit 42 of the electronic control circuit 38. In the input / output unit 42, the string vibration signal is converted into a digital signal by an A / D converter,
(Fast Fourier transform) is subjected to Fourier transform by processing and processed as a line spectrum signal.

The electronic control circuit 38, for the line spectrum signal,
The following arithmetic processing is performed.

For example, an inharmonicity correction operation,
The calculation of the virtual string vibration data and the attenuation correction calculation are performed, and the first and second virtual string data are respectively subjected to inverse Fourier transform to calculate the first and second virtual string vibration signals.

The first and second virtual string vibration signals calculated and stored at every 5 [msec] after striking by the electronic control circuit 38 are converted into analog signals by the D / A converter in the input / output unit 42 in the performance mode. And output to the drive circuit 43 or 44 as the first and second virtual string vibration signals, respectively.

The drive circuit 43 drives the actuator 35 for driving the soundboard, which is fixed to the soundboard 25 and vibrates the soundboard 25 to obtain sound. The drive circuit 44 drives the external speaker 36.

Therefore, the drive circuit 43 or 44 operates according to the setting of the mode switch 37, and the sound board 25 or the external speaker 36
Will be pronounced.

The electronic control circuit 38 for performing the above arithmetic processing and the like has a well-known configuration, and includes a CPU 45, a ROM 46, a RAM 47, and an input / output unit 42. The input / output unit 42 of the electronic control circuit 38 has an A / D converter, a D / A converter, a multiplexer, and the like, and a backup RAM 48 is connected to the CPU 45 of the electronic control circuit 38 by a bus. Configuration. A clock circuit (clock generator) 49 supplies a clock signal to the CPU 45. 50 is a power supply (battery) for the backup RAM 48.

The backup RAM 48 is a storage circuit for storing a line spectrum signal indicating the string vibration state, and has a predetermined storage capacity.

Further, reference numeral 51 denotes a hammer speed detection circuit which calculates and detects a hammer speed based on the detection signal of the optical sensor 32, 52 denotes an audio output terminal, and 53 denotes a MIDI output terminal.

Therefore, the key number of the key 22 pressed from the key sensor 33, the hammer speed from the hammer speed detection circuit 51, the high cut filter
Signals indicating the vibration state of the string 23 from 41 are respectively input.

Then, the electronic control circuit 38 sends a drive signal from the input / output unit 42 to the drive circuits 43 and 44, and outputs the drive signal to the audio output terminal 52.
To select and output an audio output signal, and to the MIDI output terminal 53, a MIDI signal.

Therefore, in this vertical piano, as in a normal piano, the strings are struck by the hammer 28 via the action 27 by pressing the keys of the player, and a desired sounding (string striking sound) is obtained.

In this vertical piano, the first,
A line spectrum signal indicating the vibration state of the second virtual string is calculated and stored.

Then, at the time of the performance, the sounding means (35 or 36) generates a sound based on the line spectrum of the virtual string simultaneously with the sounding of the struck string. As a result, it is possible to obtain a tone with a tone and volume similar to or higher than that of the conventional three-string piano.

In other words, the calculation of the line spectrum indicating the vibration state of the virtual string is performed to obtain a rich tone and volume similar to or higher than that of the conventional three-string piano.

 For example, this is performed to slightly shift the pitch.

This means that the sound of the single-string vertical piano is stored in advance as digital signals for all 88 × n (for example, five steps depending on the key pressing strength) according to the hammer speed. And the digital data is 0.3 cents or
Stagger the memory slightly by 0.2 cents. When a certain key is pressed, the shifted sound stored in the memory is read out based on the key number and the hammer speed (or the key pressing speed) and transmitted to the speaker to produce a raw sound (stringing sound).
One and two generated sounds slightly deviated from this occur almost simultaneously.

In this case, the rise of the sound of the acoustic piano is about 20 msec for the bass and about several msec for the treble.
It is assumed that the timing of the sounding timing is adjusted according to these sound ranges.

 It is also performed to adjust the line spectrum.

Noise-like harmonics are removed by a low-pass filter. If the bass strings are too short, excessive inharmonicity will occur. In other words, the pitch of the harmonics is excessively shifted, and the sound quality is degraded, for example, the sense of pitch is lost. Therefore, by calculating each harmonic component of the stored sound so as to shift its frequency until it becomes appropriate and storing it again in the memory, a sound with a good sense of pitch can be obtained. At this time, it is better to set a weak sound performance state such as shortening the string striking distance so that the raw sound during the performance is reduced. For example, a player may play by depressing a soft pedal. Alternatively, the raw sound is immediately stopped by a performance technique of releasing the key immediately after the key is pressed. Further, there is also an effect that partial tones other than the integer harmonics are canceled and generated by electrical processing (for example, using a band-pass filter such as a tuner).

Hereinafter, the operation will be specifically described with reference to flowcharts and graphs.

First, recording of a line spectrum signal indicating a vibration state of each string 23 due to striking will be described. After this recording, the vibration signal of the virtual string is calculated and stored by data processing.

In this case, the electronic control circuit
Set 38 to record mode.

In the recording mode, the key sensor 33 detects the key number of the pressed key 22 when the hammer 28 is rotated by the key press and the string 23 stretched on the frame 21 is struck. The corresponding piezoelectric element 30 detects the vibration state of the string 23 as an electric signal. Further, the hammer speed is detected by the optical sensor 32 and the hammer speed detection circuit 51. These detection signals are input to the input / output unit 42 of the electronic control circuit 38, subjected to signal processing, and stored as a line spectrum indicating the vibration state of the string.

FIG. 3 is a flowchart showing the procedure of the recording process. The electronic control circuit 38 stores actual string vibration data for all the strings 23 according to this program.

First, the CPU 45 and other initialization processing are performed, and a variable N is set to 0 (step S31). The variable N is a variable indicating the number of data.

Next, a key operation signal is input from the key sensor 34 (S3
2). As a result, the key number of the pressed key 22 is detected.

Further, the hammer speed is input from the hammer speed detection circuit 51 (S33).

Then, the string vibration signal detected by the piezoelectric element 30 is A / D converted at predetermined time intervals and input as sampling data (S34). In the string vibration signal in this case, harmonic components are removed as noise by the high cut filter 41. Further, the sampling interval of the string vibration signal is set to 1/2 or less of the shortest cycle component to prevent aliasing. The A / D conversion is started at the same time as the start of sound generation, and ends when the sound is considered to have attenuated and silenced.

Next, the sampling data is Fourier-transformed by the fast Fourier transform program to calculate a line spectrum (S35).

Further, real string vibration data, which is a set of a key number, a hammer speed, and a line spectrum, is temporarily stored in the RAM 47 (S
36).

Then, the number of data is incremented by 1 (S3
7) It is confirmed whether the recording mode has been completed based on the input from the mode changeover switch 37 (S38). If not completed, the process returns to step S32.

This recording process is executed at least once at the beginning to create a tone of a mono-chord piano. Thereafter, it may be executed again at a time desired by the player.

In addition, the player changes the key depression strength in the order of the keys from the 1st to the 88th in the normal key number, for example, pp, p, mf, f, ff
The key is pressed and recorded for five steps, such as.

By this recording process, the line spectrum of the vibration of a single string actually struck with respect to the pressed key is temporarily stored in the RAM 47 as actual string vibration data together with its key number and hammer speed. The total number N of data in this case is 88 × n. n is the number of steps of the key pressing strength, for example, five.

After the line spectrum signal is recorded, data processing for calculating a line spectrum signal indicating a desired virtual string vibration state is performed based on the line spectrum signal and the like.

The data processing is executed by the electronic control circuit 38 by switching the mode changeover switch 37 to the data processing mode.

FIG. 4 is a flowchart showing the data processing program.

Referring to this figure, first, 1 is substituted for the counter CNT to initialize (S41).

Next, the actual string vibration data specified by the data number
The data is read from the RAM 47 (S42).

First, a non-harmonicity correction process is performed on the realized vibration data (S43).

FIG. 5A is a graph of a line spectrum for explaining anharmonicity correction of the actual string vibration data.

This correction corrects, for example, the frequency of the n-th harmonic to a frequency at which moderate harmonicity occurs with respect to the frequency of the higher harmonic component shown in the line spectrum. In the graph,
Indicates vibration data of a real string, and ○ indicates vibration data after anharmonicity correction.

When fundamental f ₀ during pronunciation (t _0), the n-order harmonic nf ₀ is the frequency represented by the corrected nf ₀ '. In this case, the strength is the same. In addition, the correction in t ₁ after 5msec, the 5
Correction of higher order side harmonics at t ₂ after msec also corrected to lower the frequency as well.

For example, an arithmetic expression (expression) or a map that defines the mutual relationship between the key number and the parameter b value is stored in the ROM 46 in advance as a method for quantitatively determining the appropriate inharmonicity (inharmonicity).

And the vibration data of the real string that was read this time (S42)
In accordance with the key number of, the parameter b value indicating appropriate incongruity is obtained according to the arithmetic expression or map stored in the ROM.

Based on the parameter b value obtained in this way, correction is performed to reduce the frequency of the higher harmonics of the actual string vibration data so that there is a difference between the nth harmonic and an appropriate pitch (pitch). As a result, data after anharmonicity correction is obtained. This data is the data of the time t _0.

1200 · log ₂ (f _n / n · f ₀ ) = b · n ²
... where f _n [Hz] is the frequency of the harmonic and nf ₀ [Hz] is the nth
This is the frequency of the next harmonic. Note that n is an integer, and the unit on the right side is cents.

As described above, the frequency of the n order harmonic, is to reduce the correction to the f _n.

Next, in step S44, virtual string vibration data is calculated based on the actual string vibration data after the inharmonicity correction processing.

FIG. 5B is a graph for explaining the calculation of the first virtual string vibration data and the second virtual string vibration data. In the figure, □ is the first virtual string vibration data (the right string), △ is the second
Virtual string vibration data (left string), ● and ○ indicate real string vibration data after the inharmonicity correction processing.

This correction is based on the fundamental tone f ₀ and harmonic 2f
_This is a correction for increasing or decreasing the frequency from _{0 to} nf ₀ ′, and the base tone f ₁ and the overtones 2f _{1 to} nf ₁ ′ of the first virtual string vibration data that are 0.2 cents lower.
And the fundamental tone f ₂ and the overtones 2f _{2 to} nf ₂ ′ of the second virtual string vibration data 0.3 cents higher.

In order to create a piano sound having three strings for one key, non-harmonicity correction is performed on real string vibration data ● obtained by striking a real one string (center string). The first virtual string vibration data (right string) □, the second virtual string vibration data (left string) て based on the data ●, ○ after the harmony correction processing.
Is calculated.

Here, the pitch of the right string is 0.2 cents lower than the pitch of the center string, while the pitch of the left string is 0 cents lower than that of the center string.
An example is shown where the setting is three cents higher. Note that the pitch difference between both the left and right strings with respect to the center string may not be uniform. It is assumed that the pitch difference parameter that determines the pitch is stored in the ROM 46 in advance corresponding to each key number.

Then, the anharmonicity corrected data (f ₀ , 2f ₀ ,..., N)
f ₀ ′) is reduced by 0.2 cents to calculate first virtual string vibration data (f ₁ , 2f ₁ ,..., nf ₁ ′...).
Frequency of the fundamental tone f ₁ is relation _{{-0.2 = 1200log 2 (f 1} /
f ₀ ) Calculated from｝. Frequency of the harmonic 2f ₁ ··· also calculated in the same manner following.

Further, the anharmonicity corrected data (f ₀ , 2f ₀ ,..., N
f ₀ 'second virtual string vibration data ...) 0.3 cents higher _{(f 2, 2f 2, ·····} nf 2' ····) is calculated.
Frequency of the fundamental tone f ₂ is relation _{{0.3 = 1200log 2 (f 2} /
f ₀ ) Calculated from｝. Frequency of the harmonic 2f ₂ ··· is also calculated in the same manner following.

Next, in step S45, attenuation correction processing is performed based on the virtual string vibration data after the virtual string vibration data calculation processing.

FIG. 5 (C) is a graph of a line spectrum for explaining the intensity attenuation correction with time.

In the figure, □ indicates first virtual string vibration data, ■ indicates first virtual string data after attenuation correction, △ indicates second virtual string vibration data, and 、 indicates second virtual string data after attenuation correction.

This correction is performed such that the elapsed time (t ₁ ) after the sound generation (t ₀ ) is set so that the attenuation of the line spectrum intensity with the passage of time of the first virtual string vibration data □ and the second virtual string vibration data と becomes a desired attenuation. , T ₂ ), the intensity is increased or decreased, and the first and second
The virtual string data 弦 and ▲ are calculated.

First, the attenuation characteristics of the real string vibration data included in the first virtual string vibration data □ and the second virtual string vibration data △ are corrected. In general, the intensity I (t) at time t due to energy loss in the process of transferring energy from the strings to the soundboard via the pieces.
Is smaller than the preferred target value. Conversely, only the specific harmonic component has a slow decay, and the balance with other harmonics may be lost.

In this case, the intensity correction rate ΔI (t) for each elapsed time for each fundamental tone and each overtone is stored in the ROM 46 in advance.

Intensity correction value DI at time t after sounding by striking
(T) is calculated as in the following equation based on the intensity I (o) at the time of sound generation.

DI (t) = I (o) × ΔI (t) After the sound is generated, the intensity correction for each of the fundamental tone and each overtone at time t is performed by the following equation.

I (t) = I (t) + DI (t) I (t) on the left side represents the intensity after attenuation correction, and I (t) on the right side.
(T) indicates the intensity before correction, and DI (t) indicates the intensity correction value at time t.

Then, this correction operation is performed for each fundamental tone, each overtone, and each time.

FIGS. 5D and 5E show the first virtual string data and the second virtual string data calculated as described above, respectively, as line spectra.

Next, in step S46, the line spectrum of the first virtual string data (FIG. 5 (D)) and the line spectrum of the second virtual string data (FIG. 5 (E)) obtained by each of the above processes are obtained. The first and second virtual string vibration signals are calculated by performing an inverse Fourier transform.

Then, the first and second virtual string vibration signals, the key number, and the hammer speed are stored in the backup RAM 48 as first and second virtual string vibration data (S47).

Next, by checking whether the counter value matches the data number N (S48), steps S42 to S47 are repeated while incrementing the counter CNT by one (S49) until the processing for all data is completed (S49). Run.

As described above, when the calculation and storage of the virtual string data are completed, the CPU 45 executes the program shown in FIG. 6 during the subsequent actual performance. At this time, the mode switch 37 has been switched to the performance mode.

At the time of the performance, the striking sound is produced by the player's key depression. At the same time, the processing shown in this flowchart is performed, and the sound is produced from the soundboard 25 or the external speaker 36 via the drive circuit 43 or 44. . These means 2
The pronunciation by 5, 36 is made based on the virtual string data.

First, a detection signal from the key sensor 34 is input and a hammer speed is calculated and input for the key that has been pressed (S61).

Next, the first and second virtual string vibration signals corresponding to the actually struck string 23 and the key depression strength (calculated from the hammer speed) are read from the backup RAM 48 (S62).

Then, through a subroutine process, a three-dimensional map (RO
In accordance with the detected key number and hammer speed, an appropriate sounding time is calculated according to the detected key number and the hammer speed (S63).

At the sounding time calculated in this way, the first and second virtual string vibration signals are output from (selected) any one of the actuator 35 for driving the soundboard 25, the external speaker 36, and the audio output terminal 52. (S64). Also, MID
The key number, the hammer speed (velocity), and the sounding timing (timing) are output to the I output terminal 53 (S65).

Then, the setting of the mode changeover switch 37 is checked (S66).
61 to S65 are repeatedly executed.

In addition, by not operating the electric system, it can be easily used as a single-string piano and can be used as a practice piano having a low volume.

Furthermore, a MIDI signal can be output via the MID output terminal 53, and ensemble performance with other electronic musical instruments, MIDI equipment (music computer, etc.) can be performed.

Also, considering the MIDI signal delay processing [500 msec], ensemble with an automatic piano becomes possible.

<Effects of the Invention> As described above, according to the keyboard instrument of the present invention, the timbre is remarkably improved as compared with the conventional monochord piano. The volume has also been improved. Further, the volume can be adjusted by an amplification factor or the like. And since the volume increases, it is possible to perform a weak sound.

These timbres and volumes can be raised to a level equal to or higher than that of a piano having three strings.

Also, compared to a three-string piano, this single-string piano has less tension acting on the frame, so the frame is lighter,
Miniaturization can be realized.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram illustrating a schematic configuration of a keyboard instrument according to the present invention, FIG. 2 is a block diagram illustrating an overall configuration of a keyboard instrument according to an embodiment of the present invention, and FIG. FIG. 4 is a flowchart showing a data processing procedure according to one embodiment, and FIGS. 5A to 5E are virtual string vibrations according to one embodiment. FIG. 6 is a graph showing a line spectrum for explaining a state calculation process. FIG. 6 is a flowchart showing a performance process according to an embodiment. 100 storage means, 200 key detection means, 300 selection means, 400 sound generation means.

Claims (1)

(57) [Claims] 1. A keyboard musical instrument having one or two strings stretched corresponding to a plurality of keys, respectively, wherein a vibration state of the string is detected, and at least the detected vibration state is detected. Storage means for calculating and storing the vibration state of the virtual string having substantially the same pitch as the stretched string based on the spectral characteristics indicating the stretched string; key detection means for detecting a pressed key during performance; Selecting means for selecting from the storage means the vibration state of the virtual string having substantially the same pitch as the stretched string corresponding to the selected key; and sounding means for converting the selected vibration state into sound and outputting the sound. A keyboard instrument provided with: