JP2015082089A - Electronic string musical instrument, method for controlling musical sound, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic string musical instrument which accurately performs a pitch extraction.SOLUTION: An electronic guitar 1 has a pitch extraction circuit PC which detects the vibration of a stretched string. A plurality of low-pass filters classifies a plurality of frets on the finger board into one group or a plurality of groups, which is provided for each classified group, and has a filtering characteristic corresponding to each group. A fret scans part FS detects which fret is operated from among the plurality of frets. A microcomputer subjects a vibration signal of the string detected by the pitch extraction circuit PC to a filtering process by the low-pass filter corresponding to the group to which the fret detected by the operation of the fret scan part FS belongs. The microcomputer performs a process of extracting a pitch of the music sound to be generated based on the vibration signal of the string subjected to the filtering process.

Description

  The present invention relates to an electronic stringed instrument such as an electronic guitar, and more particularly to an electronic stringed instrument, a musical tone control method, and a program for generating musical tones of various pitches by extracting pitches from input waveform signals.

Conventionally, musical tone generation is performed by extracting the pitch (fundamental frequency) from the waveform signal generated by the performance operation of a natural musical instrument and controlling the sound source device composed of electronic circuits to artificially obtain sounds such as musical sounds. Equipment has been developed.
In an electronic stringed instrument such as an electronic guitar equipped with such a musical sound generating device, a fret operation for pressing a string with a finger and a picking for playing a string are performed as performance operations, and musical sounds corresponding to these performance operations are generated. .
An electronic stringed instrument that detects a fret operation and picking to generate a musical sound is described in, for example, Patent Document 1.
Here, when extracting the pitch of a string that vibrates due to picking, a harmonic waveform is superimposed on the vibration of the string. Therefore, pitch extraction may be performed after passing the vibration waveform of the string through a low-pass filter.
When the harmonic waveform is removed by the low-pass filter, the pitch can be extracted more accurately.

JP 2003-084766 A

However, in the prior art in which pitch extraction is performed by removing the overtone waveform with a low-pass filter, the cutoff frequency of the low-pass filter is fixed. Therefore, although it is effective when the string is pressed with a specific fret, the waveform of the harmonic overtone in the vibration of the string cannot be sufficiently removed when the string is pressed with another fret or an open string.
As a result, accurate pitch extraction cannot be performed, so that the pitches that are pronounced may not be appropriate.
In an electronic stringed instrument, crosstalk may occur in the strings adjacent to the picked string, and in this case as well, it is a factor that prevents accurate pitch extraction.
That is, in the prior art, it is difficult to accurately perform pitch extraction in an electronic stringed instrument.

  The present invention has been made in view of such circumstances, and an object thereof is to more accurately perform pitch extraction in an electronic stringed instrument.

In order to achieve the above object, an electronic stringed musical instrument according to one aspect of the present invention is provided.
A string vibration detecting means for detecting vibration of the stretched string;
A plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each classified group, and a plurality of filter means having a filtering characteristic corresponding to each group,
Fret operation detecting means for detecting which one of the plurality of frets has been operated;
Filter control means for filtering the vibration signal of the string detected by the string vibration detection means by the filter means corresponding to the group to which the fret whose operation is detected by the fret operation detection means;
Pitch extraction means for executing processing for extracting the pitch of the musical sound to be generated based on the vibration signal of the string filtered by the filter means;
Have

  According to the present invention, pitch extraction in an electronic stringed instrument can be performed more accurately.

It is a schematic diagram which shows the structure of the principal part of the electronic guitar which concerns on a present Example. It is a block diagram which shows the whole circuit. It is a figure which shows the fret detection circuit for detecting the stringing state of a fret. It is a block diagram which shows the concrete function structure of a pitch extraction circuit and a microcomputer. It is a block diagram which shows the specific structure of the pitch extraction circuit which concerns on a present Example. It is a circuit diagram which shows the structural example of the low-pass filter in a low-pass filter process part, an amplifier circuit, and a zero crossing point taking-in circuit. FIG. 7 is a diagram showing parameters and filter coefficients of the circuit element of FIG. 6 for determining the cut-off frequency in the first to third fret groups, and FIG. 7A is a diagram of FIG. FIG. 7C shows the case of the second fret group, and FIG. 7C shows the case of the third fret group. FIG. 8A is a diagram illustrating a relationship between crosstalk coefficients in each string and adjacent strings, FIG. 8A is a relationship between crosstalk coefficients in the first fret group, and FIG. 8B is a crosstalk coefficient in the second fret group. FIG. 8C is a diagram showing the relationship between the crosstalk coefficients in the third fret group. It is a schematic diagram which shows the case where the F major chord is pressed. It is a schematic diagram which shows the case where the A # major chord is pressed. It is a schematic diagram which shows the outline | summary of the process at the time of a microcomputer generating a musical sound. It is a flowchart which shows the fret detection process routine which a microcomputer performs. It is a flowchart which shows the interrupt routine which shows a process when an interrupt is applied to the microcomputer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Example]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, a case where the present invention is applied to an electronic guitar (guitar synthesizer) will be described as an example. Note that the present invention is not limited to this and can be applied to other types of electronic musical instruments.

FIG. 1 is a schematic diagram illustrating a configuration of a main part of an electronic guitar 1 according to the present embodiment.
As shown in FIG. 1, the electronic guitar 1 includes six strings STG1 to STG6 stretched on the fingerboard FB. By performing fret and picking on each string, the electronic guitar 1 The user can perform with the same operation as a natural musical instrument. As shown in FIG. 1, the electronic guitar 1 is provided with six strings STG1 to STG6 stretched on the fingerboard FB, and includes a scan pulse generator PG that inputs a scan pulse to each string. The electronic guitar 1 detects each operation by the fret scanning unit FS and the pitch extraction circuit PC when fret or picking is performed on each string.
FIG. 2 is a block diagram showing the entire circuit. The pitch extraction circuit PC converts the vibration of each string into an electrical signal, acquires the zero-cross point of the vibration waveform and the absolute value of the amplitude, and outputs them to the microcomputer MCP.

  The microcomputer MCP has a memory such as a ROM and a RAM including a pitch data conversion table (pitch table), which will be described later, and a timer TMR, and controls signals to be supplied to the sound source generator SOB. The sound generator SOB includes a sound source SS, a digital-analog converter circuit D / A, an amplifier circuit AMC, and a speaker SP. Note-on (sounding), note-off (silence) from the microcomputer MCP, and a pitch for changing the frequency. A musical tone having a pitch corresponding to the instruction signal is emitted. Note that an interface in the MIDI (Musical Instrument Digital Interface) format is provided between the input side of the sound source SS and the data bus BUS of the microcomputer MCP. Of course, when the sound source SS is provided in the guitar body, another interface may be used. When the address read signal AR from the microcomputer MCP is input, the address decoder DCD reads the string number read signal RDI, the time read signal RDj (j = 1 to 6), the peak values of MAX and MIN, and the current value at that time. Instantaneous value read signal RDAI (I = 1 to 18) is output to pitch extraction circuit PC.

The microcomputer MCP always detects the stringed state of each fret in each string as interrupt processing at regular intervals (for example, every 1 ms). The pressed state detection process is executed as a parallel process separately from pitch extraction by picking each string.
FIG. 3 is a diagram showing a fret detection circuit FDC for detecting a fret-pressed state. The fret detection circuit FDC is provided in the fret scan unit FS.
As shown in FIG. 3, the fret detection circuit FDC has a configuration in which 22 selection lines KI0 to KI21 corresponding to the number of frets and 6 signal lines KC0 to KC5 corresponding to the number of strings are arranged in a matrix. have.

The selection lines KI0 to KI21 are sequentially switched to an active state every predetermined time (for example, 1 ms). These selection lines KI0 to KI21 are pulled up to a high level (for example, 5v). If there is a string that is in contact with the fingerboard FB by pressing the selected line KI0 to KI21 in an active state, a high level signal is read from the signal lines KC0 to KC5 corresponding to the string.
That is, the fret detection circuit FDC switches the selection lines KI0 to KI21 to an active state one by one every predetermined time, reads the state (high level or low level) of the signal lines KC0 to KC5, and for all the frets, Detect which position is pressed.

FIG. 4 is a block diagram showing specific functional configurations of the pitch extraction circuit PC and the microcomputer MCP. The pitch extraction is executed mainly by functions described below of the pitch extraction circuit PC and the microcomputer MCP.
As shown in FIG. 4, the pitch extraction circuit PC includes a low-pass filter LPF, an amplifier circuit AMC, a zero-cross point capturing circuit ZCR, and an absolute value capturing circuit ABS. Note that the low-pass filter LPF, the amplifier circuit AMC, the zero-cross point capturing circuit ZCR, and the absolute value capturing circuit ABS constitute a low-pass filter processing unit LA described later.
A signal having a waveform generated in each string by picking is input to the low-pass filter LPF from the hex pickup, and the low-pass filter LPF cuts the high-frequency component of the input signal and passes only the low-frequency component. .
The amplifier circuit AMC amplifies the output signal of the low-pass filter LPF according to the set gain, and outputs the amplified signal to the zero-cross point capturing circuit ZCR and the absolute value capturing circuit ABS.

The zero-cross point capturing circuit ZCR detects a zero-cross point of the input waveform signal, and outputs a high-level signal when the signal is positive from the zero-cross point and a low-level signal when the signal is negative. Note that both the inverted signal (inverted output) and the non-inverted signal (non-inverted output) are input to the microcomputer MCP as the output signals of the zero-cross point capturing circuit ZCR.
The absolute value fetch circuit ABS detects peak values on both the positive and negative sides of the input waveform signal, and inputs the absolute value and sign of the peak value to the microcomputer MCP.

The microcomputer MCP includes an interrupt control circuit IC, a timer TMR, an analog-digital conversion circuit A / D, and a memory MEM.
The interrupt control circuit IC receives the non-inverted output and the inverted output of the zero-cross point capturing circuit ZCR, and generates an interrupt signal at these rising edges. That is, the interrupt control circuit IC generates an interrupt signal at the timing when the waveform signal generated in each string by picking crosses zero. The interrupt control circuit IC outputs the generated interrupt signal to the timer TMR.

When an interrupt signal is input from the interrupt control circuit IC, the timer TMR outputs the input time t (in the case of an interrupt signal by non-inverted output) and time T (in the case of an interrupt signal by inverted output) to the memory MEM. To do.
The analog-digital conversion circuit A / D converts the absolute value of the peak value input from the absolute value acquisition circuit ABS into a digital signal and outputs it to the memory MEM. The analog-to-digital conversion circuit A / D outputs the code input together with the absolute value of the peak value together with the digitized peak value to the memory MEM.

The memory MEM stores the times t and T input from the timer TMR, the absolute value (digital value) of the peak value, and the sign. The times t and T stored in the memory MEM are calculated by calculating the difference between the times t and T stored last time by the microcomputer MCP and the times t and T stored this time, and calculating the frequency (pitch which is the pitch of the musical sound to be generated). Used when seeking.
The memory MEM stores a fret-frequency data table (not shown) indicating the relationship between the frets of each string and the frequency.

In the fret-frequency data table, the scale A4 is set to 442 Hz, the frequency corresponding to each string, and the pitch code (key code) according to the fret position is stored in association with each other.
The memory MEM stores a pitch data conversion table (not shown) for converting the frequency acquired by the pitch extraction into pitch data (key code).
In the pitch data conversion table, the frequency obtained by pitch extraction is stored in association with pitch data (key code) proportional to cent.

  When picking is performed while referring to these data stored in the memory MEM, the microcomputer MCP determines a pitch according to the result of the fret scan and the result of the pitch extraction, and generates a musical sound.

Next, a specific configuration of the pitch extraction circuit PC in the present invention will be described.
In the pitch extraction circuit PC according to the present invention, 22 frets are divided into one or a plurality of groups (fret groups), and a low-pass filter having a different cutoff frequency is provided for each group. . Further, a low-pass filter for each of these groups is installed for each of the six strings with a cut-off frequency corresponding to each string. In the present embodiment, 22 frets FB1 to FB22 from the first to the 22nd frets are divided into the first fret group FG1 to the frets FB1 to FB6, the second fret group FG2 to the frets FB7 to F14, and the frets FB15 to FB22. To the third fret group FG3. The first fret group FG1 includes the case of an open string.

  When pitch extraction is performed, the fret group (hereinafter referred to as “operation fret group”) is controlled by the microcomputer MCP depending on which one of the frets FB1 to FB22 is pressed or an open string. Determined. Then, the microcomputer MCP selects the low-pass filter of the operation fret group corresponding to the strings STG1 to STG6 that are struck. The low-pass filter selected here is hereinafter referred to as “selected low-pass filter” as appropriate.

In the pitch extraction circuit PC, when a string is performed, the pitch is extracted after filtering the waveform signal using a selected low-pass filter.
Further, in the pitch extraction circuit PC, when the pitch extraction of the strings STG1 to STG6 that have been played is performed, a process of reducing crosstalk from adjacent strings is performed. Specifically, in each string, a crosstalk coefficient used for reducing crosstalk with respect to adjacent strings is set for each of the first to third fret groups FG1 to FG3. Note that the crosstalk coefficient is individually set for a string having a string number one larger and that used for a string having a smaller string number. In the processing for reducing the crosstalk, which crosstalk coefficient is used is selected by the microcomputer MCP.

Hereinafter, the configuration of the pitch extraction circuit PC will be described with reference to FIG.
FIG. 5 is a block diagram showing a specific configuration of the pitch extraction circuit PC according to the present embodiment.
As shown in FIG. 5, the pitch extraction circuit PC includes a crosstalk reduction unit CTR, a low-pass filter processing unit LA, and a selector SEL. Note that the pitch extraction circuit PC shown in FIG. 5 shows the configuration for one string, and the actual pitch extraction circuit PC has six configurations corresponding to the strings STG1 to STG6, Implemented in parallel.

The crosstalk reduction unit CTR includes a lower coefficient selection unit 110, multiplication units 120 and 140, an upper coefficient selection unit 130, and an addition unit 150.
The lower coefficient selection unit 110 uses the crosses corresponding to the first to third fret groups FG1 to FG3 for a string (string number n-1) that is one string number smaller than the string that has been played (string number n). Coefficient storage units 111 to 113 for storing talk coefficients are provided. The coefficient storage unit 111 stores a crosstalk coefficient corresponding to the first fret group for the string of the string number n-1. Similarly, the coefficient storage unit 112 stores crosstalk coefficients corresponding to the second fret group, and the coefficient storage unit 113 stores crosstalk coefficients corresponding to the third fret group FG3. The lower coefficient selection unit 110 selects and selects one of these coefficient storage units 111 to 113 in response to an instruction from the microcomputer MCP (an instruction to specify a string operation fret group of the string number n−1). The crosstalk coefficient obtained is output to the multiplier 120.

  Multiplier 120 multiplies the signal input from the pickup for the string of string number n−1 by the crosstalk coefficient input from lower coefficient selector 110 and outputs the multiplication result to adder 150. In addition, in the multiplication unit 120, when the vibration of the string having the string number n-1 is multiplied by the crosstalk coefficient, the multiplication is performed with the phase inverted in order to cancel the crosstalk to the string having the string number n. Done.

  The upper coefficient selection unit 130 calculates crosstalk coefficients corresponding to the first to third fret groups FG1 to FG3 for a string (string number n + 1) having one string number larger than the string that has been played (string number n). Coefficient storage units 131 to 133 for storing each are provided. The coefficient storage unit 131 stores a crosstalk coefficient corresponding to the first fret group for the string with the string number n + 1. Similarly, the coefficient storage unit 132 stores crosstalk coefficients corresponding to the second fret group, and the coefficient storage unit 133 stores crosstalk coefficients corresponding to the third fret group FG3. The upper coefficient selection unit 130 selects one of these coefficient storage units 131 to 133 in response to an instruction from the microcomputer MCP (an instruction to specify a string operation fret group of the string number n + 1), and the selected crosstalk The coefficient is output to the multiplier 140.

Multiplier 140 multiplies the signal input from the pickup for the string of string number n + 1 by the crosstalk coefficient input from upper coefficient selector 130 and outputs the multiplication result to adder 150. In addition, in the multiplication unit 140, when the vibration of the string with the string number n + 1 is multiplied by the crosstalk coefficient, the multiplication is performed with the phase inverted in order to cancel the crosstalk to the string with the string number n. .
The adding unit 150 adds the signal input from the pickup for the string of the string number n, the multiplication result input from the multiplication unit 120, and the multiplication result input from the multiplication unit 140, and low-pass filtering the addition result Output to part LA. As a result, the low-pass filter processing unit LA outputs a signal in which the crosstalk from the string of the string number n−1 and the string of the string number n + 1 is canceled as the string signal of the string number n.

The low-pass filter processing unit LA includes low-pass filter processing units 210, 220, and 230. The low-pass filter processing unit LA includes a low-pass filter LPF, an amplifier circuit AMC, a zero-cross point capturing circuit ZCR, and an absolute value capturing circuit ABS.
In the low-pass filter processing unit 210, the low-pass filter LPF is set to a cutoff frequency corresponding to the first fret group FG1. Then, the low-pass filter LPF cuts a high frequency component equal to or higher than the cutoff frequency in the addition result signal input from the addition unit 150, and passes the low frequency component signal. The output of the low pass filter LPF is output to the amplifier circuit AMC.

The amplifier circuit AMC amplifies the output signal of the low-pass filter LPF according to the set gain, and outputs the amplified signal to the zero-cross point capturing circuit ZCR and the absolute value capturing circuit ABS.
The zero-cross point capturing circuit ZCR includes a comparator and detects a zero-cross point of an input waveform signal. The zero-cross point capturing circuit ZCR outputs a high-level signal when the level of the input waveform signal is positive from the zero-cross point, and outputs a low-level signal when the level is negative.
The absolute value fetch circuit ABS detects peak values on both the positive and negative sides of the input waveform signal, and inputs the absolute value and sign of the peak value to the microcomputer MCP.

Here, the configurations of the low-pass filter processing units 210, 220, and 230 are different from each other in the cutoff frequency of the low-pass filter LPF, while the configurations of the amplifier circuit AMC and the zero-cross point capturing circuit ZCR are the same.
That is, the low pass filter LPF of the low pass filter processing unit 220 is set to a cutoff frequency corresponding to the second fret group FG2. Then, the low-pass filter LPF cuts a high frequency component equal to or higher than the cutoff frequency in the addition result signal input from the addition unit 150, and passes the low frequency component signal. The output of the low pass filter LPF is output to the amplifier circuit AMC.

The low-pass filter LPF of the low-pass filter processing unit 230 is set to a cutoff frequency corresponding to the third fret group FG3. Then, the low-pass filter LPF cuts a high frequency component equal to or higher than the cutoff frequency in the addition result signal input from the addition unit 150, and passes the low frequency component signal. The output of the low pass filter LPF is output to the amplifier circuit AMC.
The selector SEL responds to an instruction from the microcomputer MCP (instruction to specify a string operation fret group of the string number n), and outputs (zero cross points, absolute values of peak values, and signs) of the low-pass filter processing units 210, 220, and 230. ) And outputs the selected output to the microcomputer MCP.

Next, a specific configuration example of the low-pass filter processing unit LA will be described.
FIG. 6 is a circuit diagram illustrating a configuration example of the low-pass filter LPF, the amplifier circuit AMC, and the zero-cross point capturing circuit ZCR in the low-pass filter processing unit LA. In FIG. 6, only the main part of the circuit constituting the low-pass filter processing unit LA is shown.
In FIG. 6, the low-pass filter LPF is configured as a multiple feedback low-pass filter including capacitors C1, C2, and C5, a resistor R1, and an operational amplifier OP1. The amplifier circuit AMC is configured as a negative feedback amplifier circuit including capacitors C3 and C4, a resistor R2, and an operational amplifier OP2. Further, the zero cross point fetch circuit ZCR is constituted by a comparator CMP.

The low-pass filter LPF receives the addition result signal input from the adding unit 150, cuts a high frequency component equal to or higher than the cutoff frequency determined by the capacitors C1 to C4 and the resistor R1, and passes the low frequency component signal.
The amplifier circuit AMC amplifies the output signal of the low pass filter LPF according to the gain set in the operational amplifier OP2.
The zero cross point capturing circuit ZCR compares the output signal of the amplifier circuit AMC with the signal of the zero level, and outputs a high level signal when the output signal of the amplifier circuit AMC is larger than the zero level signal. When the output signal of the amplifier circuit AMC is smaller than the low level signal, the low level signal is output.
As the low-pass filter processing unit LA, for each string, three sets having cutoff frequencies corresponding to the first to third fret groups FG1 to FG3 are installed, and for each of the strings STG1 to STG6, such three sets A low-pass filter processing unit LA is installed.
In FIG. 6, only one of these 18 low-pass filter processing units LA is shown, and the other low-pass filter processing units LA are not shown.

Next, the cut-off frequency of the low-pass filter and the crosstalk coefficient of each string in this embodiment will be described.
FIG. 7 is a diagram showing parameters and filter coefficients of the circuit elements of FIG. 6 for determining the cutoff frequency in the first to third fret groups FG1 to FG3, and FIG. 7A shows the first fret group FG1. 7B shows the case of the second fret group FG2, and FIG. 7C shows the case of the third fret group FG3.

As shown in FIG. 7, in the circuit shown in FIG. 6, the filter coefficient that determines the cut-off frequency of the low-pass filter LPF can be changed by changing the parameters of the resistor R1 and the capacitors C1 to C5.
For example, in FIG. 7A, for the string with the string number 1, the resistor R1 is r11 [Ω], the capacitor C1 is X11 [μF], the capacitor C2 is X21 [μF], the capacitor C3 is X31 [μF], the capacitor C4 is set to X41 [μF], and the capacitor C5 is set to X51 [μF]. As a result, the filter coefficient is FK1.

In FIG. 7A, for the string with the string number 2, the resistor R1 is r12 [Ω], the capacitor C1 is X12 [μF], the capacitor C2 is X22 [μF], the capacitor C3 is X32 [μF], and the capacitor C4 is X42 [μF] and the capacitor C5 are set to X52 [μF], and as a result, the filter coefficient is FK2.
In FIG. 7B, for the string with the string number 1, the resistor R1 is r21 [Ω], the capacitor C1 is Y11 [μF], the capacitor C2 is Y21 [μF], the capacitor C3 is Y31 [μF], and the capacitor C4 is set to Y41 [μF], and the capacitor C5 is set to Y51 [μF]. As a result, the filter coefficient is FK7.

In FIG. 7B, for the string with the string number 2, the resistor R1 is r22 [Ω], the capacitor C1 is Y12 [μF], the capacitor C2 is Y22 [μF], the capacitor C3 is Y32 [μF], and the capacitor C4 is set to Y42 [μF], and the capacitor C5 is set to Y52 [μF]. As a result, the filter coefficient is FK8.
Further, in FIG. 7C, for the string with the string number 1, the resistor R1 is r31 [Ω], the capacitor C1 is Z11 [μF], the capacitor C2 is Z21 [μF], the capacitor C3 is Z31 [μF], the capacitor C4 is set to Z41 [μF], and the capacitor C5 is set to Z51 [μF]. As a result, the filter coefficient is FK13.

For the string with the string number 2, the resistor R1 is r32 [Ω], the capacitor C1 is Z12 [μF], the capacitor C2 is Z22 [μF], the capacitor C3 is Z32 [μF], the capacitor C4 is Z42 [μF], The capacitor C5 is set to Z52 [μF], and as a result, the filter coefficient is FK4.
In this way, in the circuit shown in FIG. 6, the filter coefficient of the low-pass filter LPF can be changed by varying the parameters of the circuit elements, thereby realizing the target cutoff frequency. .

FIG. 8 is a diagram showing the relationship between the crosstalk coefficients of each string and the adjacent strings. FIG. 8A shows the relationship between the crosstalk coefficients in the first fret group FG1, and FIG. 8B shows the second fret. FIG. 8C shows the relationship between crosstalk coefficients in the third fret group FG3.
As shown in FIG. 8, in this embodiment, when a string is struck, the crosstalk coefficient for reducing the influence of the crosstalk that the string gives to the adjacent string has a larger string number side and It is set for each string on the small side. Further, in the present embodiment, such crosstalk coefficients for the adjacent strings are set corresponding to the first to third fret groups FG1 to FG3.

For example, in FIG. 8A, for the string with the string number 2, the crosstalk coefficient for the string number n-1, that is, the string with the string number 1, is P12, and the crosstalk with the string number n + 1, that is, the string with the string number 3 The coefficient is set to Q12.
In FIG. 8A, for the string with the string number 3, the crosstalk coefficient for the string with the string number n−1, that is, the string with the string number 3, is P13, and the crosstalk with respect to the string with the string number n + 1, that is, the string with the string number 3. The coefficient is set to Q13.

In FIG. 8B, for the string with the string number 2, the crosstalk coefficient for the string with the string number n-1, that is, the string with the string number 1, is P22, and the crosstalk with the string number n + 1, that is, the string with the string number 3. The coefficient is set to Q22.
In FIG. 8B, for the string with the string number 3, the crosstalk coefficient for the string number n-1, that is, the string with the string number 3, is P23, and the crosstalk with the string number n + 1, that is, the string with the string number 3. The coefficient is set to Q23.
Further, in FIG. 8C, for the string with the string number 2, the crosstalk coefficient for the string number n-1, that is, the string with the string number 1, is P32, and the crosstalk with respect to the string with the string number n + 1, that is, the string number 3. The coefficient is set to Q32.

In FIG. 8C, for the string with the string number 3, the crosstalk coefficient for the string number n−1, that is, the string with the string number 3, is P33, and the string number n + 1, that is, the crosstalk for the string with the string number 3. The coefficient is set to Q33.
In FIG. 8, there is no string with the string number n-1 for the string with the string number 1 and no string with the string number n + 1 with respect to the string with the string number 6, so the crosstalk coefficient is set to zero.
Thus, crosstalk can be reduced more appropriately by setting the crosstalk coefficients corresponding to the first to third fret groups FG1 to FG3. As a result, pitch extraction can be performed more accurately.

Next, a specific example of the operation in the pitch extraction circuit PC will be described.
FIG. 9 is a schematic diagram illustrating a case where the F major chord is pressed.
As shown in FIG. 9, when the F major chord is pressed, the strings with the string numbers 1 and 2 are the first fret, the string with the string number 3 is the second fret, the string with the string number 4 and the string number 5 Is the third fret, and the first fret is operated for the string of string number 6.

At this time, if the pitch extraction of the string of the string number 2 is performed, the vibration of the string of the string number 1 crosstalks with the waveform of the string of the string number 2, and the vibration of the string of the string number 3 is the string number 2. Crosstalk to the string waveform.
Therefore, after the phase of the vibration of the string of the string number 1 is inverted, the crosstalk coefficient is multiplied and added to the signal of the string of the string number n. As the crosstalk coefficient used at this time, the operation fret group of the string number 2 is the third fret group FG3, and therefore, the crosstalk coefficient Q31 of the string of the string number 1 in FIG. 8C is used.

At the same time, the phase of the vibration of the string with the string number 3 is inverted, and then the crosstalk coefficient is multiplied and added to the string signal with the string number n. The crosstalk coefficient used at this time is the chord crosstalk coefficient P33 of the chord number 3 in FIG. 8C because the operation fret group of the chord number 3 is the third fret group FG3.
Thereby, in the signal of the string of the string number 2, crosstalk due to the vibration of the string of the string number 1 and the vibration of the string of the string number 3 is reduced.

Then, a filtering process by the low-pass filter LPF is performed on the string signal of the string number 2 with reduced crosstalk. At this time, since the operation fret group of the string having the string number 2 is the third fret group FG3, the filter process is performed at the cutoff frequency determined by the cutoff coefficient FK14 of the string number 2 in FIG. .
Further, detection of a zero cross point, detection of a peak value, and the like are performed on the signal after the filter processing is performed in this manner, and pitch extraction processing by the microcomputer MCP is performed.

Next, another specific example of the operation in the pitch extraction circuit PC will be described.
FIG. 10 is a schematic diagram showing a case where the A # major chord is pressed.
As shown in FIG. 10, when the A # major chord is pressed, the strings of the string number 1 and string number 2 are the sixth fret, the string of string number 3 is the seventh fret, the string number 4 and the string number 5 are The 8th fret is operated for the string, and the 6th fret is operated for the string with the string number 6.

At this time, if the pitch extraction of the string of the string number 2 is performed, the vibration of the string of the string number 1 crosstalks with the waveform of the string of the string number 2, and the vibration of the string of the string number 3 is the string number 2. Crosstalk to the string waveform.
Therefore, after the phase of the vibration of the string of the string number 1 is inverted, the crosstalk coefficient is multiplied and added to the signal of the string of the string number n. As the crosstalk coefficient used at this time, the operation fret group of the string number 2 is the third fret group FG3, and therefore, the crosstalk coefficient Q31 of the string of the string number 1 in FIG. 8C is used.

At the same time, the phase of the vibration of the string with the string number 3 is inverted, and then the crosstalk coefficient is multiplied and added to the string signal with the string number n. The crosstalk coefficient used at this time is the string crosstalk coefficient P23 of the string of string number 3 in FIG. 8B because the operation fret group of string number 3 is the second fret group FG2.
Thereby, in the signal of the string of the string number 2, crosstalk due to the vibration of the string of the string number 1 and the vibration of the string of the string number 3 is reduced.

Then, a filtering process by the low-pass filter LPF is performed on the string signal of the string number 2 with reduced crosstalk. At this time, since the operation fret group of the string having the string number 2 is the third fret group FG3, the filter process is performed at the cutoff frequency determined by the cutoff coefficient FK14 of the string number 2 in FIG. .
Further, detection of a zero cross point, detection of a peak value, and the like are performed on the signal after the filter processing is performed in this manner, and pitch extraction processing by the microcomputer MCP is performed.

Next, an outline of processing when the microcomputer MCP generates musical sounds will be described.
FIG. 11 is a schematic diagram showing an outline of processing when the microcomputer MCP generates musical sounds.
In FIG. 11, if the signal having the waveform shown in FIG. 11C is input to the pitch extraction circuit PC, the non-inverted output of the zero-cross point capturing circuit ZCR corresponding to this is the waveform shown in FIG. The output has the waveform shown in FIG.

  When executing the pitch extraction process, the microcomputer MCP discards the waveform signal by regarding the pitch smaller than the predetermined peak value THLAB as noise (STEP 0 to 2). On the other hand, the microcomputer MCP is parallel to the pitch extraction process when the peak value VEL0 of STEP0 is equal to or greater than the threshold value TH0 of the peak value at STEP0 when the peak value THLAB is equal to or greater than STEPLAB at STEP0. The pitch (initial value of the pitch) is detected from the information of each fret detected by the fret string detection process executed at the beginning, and sound generation is started in STEP 1 based on the peak value of STEP 0. Specifically, the microcomputer MCP sets the velocity VEL for determining the sound volume to (VEL0 + VEL1) / 2 and starts sound generation at STEP1.

  After that, if the microcomputer MCP is equal to or greater than the predetermined peak value THLAB in STEP0 to STEP2, the peak value and sign of the waveform are set to velocity VEL ( Specifically, it is taken in as a value of the crest value VEL2) (STEP 3). Then, the microcomputer MCP produces a sound of the pitch based on the velocity VEL value detected in the pitch extraction process (note-on). When sound generation is performed, the microcomputer MCP issues a sound generation command to the sound source SS by outputting the pitch and velocity VEL values.

Thereafter, in STEP 4, the pitch extraction process is continued, and the microcomputer MCP calculates the frequency (pitch) from the difference between the time t, T stored last time and the time t, T stored this time (TP (b), TP (b ′)), correction is made for the pitch that is already sounded by this frequency.
Here, when the pitch extraction process is performed, the low-pass filter process is performed on the vibration of the string at the cut-off frequency corresponding to the operation fret group of the string that has been played. At this time, the crosstalk from adjacent strings that have been played is reduced by the crosstalk coefficient corresponding to the operation fret group in each string.

Hereinafter, the operation of the microcomputer MCP will be described with reference to flowcharts and drawings showing waveforms.
First, reference numerals in the drawings will be described.
AD: Input peak value (instantaneous value) obtained by directly reading the input waveform of the pitch extraction circuit PC by the instantaneous value read signals RDA13 to 18 in FIG.
T... Period data THLAB... Noise removal threshold in STEP0 and STEP1 TH0... Crest value judgment threshold in STEP0 TH1... Crest value judgment threshold in STEP1 VEL. Information that determines the velocity (velocity), which is determined by the maximum peak value (peak value) of the waveform at the start of sound generation.
VEL0 ... Crest value after noise removal in STEP0 (= a0)
VEL1... Peak value after noise removal in STEP1 (= b0)
VEL2 ... Peak value in STEP2 (= a1)

b: Current positive / negative flag stored in the working register B (1 at the next zero point after the positive peak, 0 at the next zero point after the negative peak)
c: Current peak value (peak value) stored in working register C
e ・ ・ ・ Previous peak value (peak value) stored in working register E
h: Period data extracted last time stored in the working register H t: Current zero-crossing time stored in the working register Tr

FIG. 12 is a flowchart showing a fret detection processing routine executed by the microcomputer MCP.
In F1, the microcomputer MCP selects one of the selection lines KI0 to KI21 (for example, the selection line KI0) to make it active.
In subsequent F2, the microcomputer MCP reads the signal levels of the signal lines KC0 to KC5. At this time, the signal level corresponding to the string being pressed has a high signal level, and the signal level corresponding to the string not being pressed has a low level.

In F3, the microcomputer MCP determines whether or not the string is pressed. The microcomputer MCP shifts to the process of F4 when the string is pressed, that is, when yes (hereinafter referred to as Y), and shifts to the process of F1 when the string is not pressed, that is, when it is no (hereinafter referred to as N). To do.
In F4, the microcomputer MCP calculates a pitch code. At this time, the microcomputer MCP calculates a pitch code at the string-pressed position.
By repeating such processing, the microcomputer MCP detects the pressed state of each string for all the frets.

  FIG. 13 is an interrupt routine showing processing when an interrupt is applied to the microcomputer MCP. In I1, the microcomputer MCP gives a string number read signal RDI to the zero-crossing time acquisition circuit ZTS via the address decoder DCD. Read the string number that specifies the string that interrupted. Then, the time information corresponding to the string number, that is, the zero cross time information is read by giving the zero cross time fetch circuit ZTS the one corresponding to any of the time read signals RD1 to RD6. This is t. Thereafter, at I2, the peak value read signal RDAI (any one of I = 1 to 12) is similarly applied to the peak value acquisition circuit PVS to read the peak value. Let this be c.

  In the subsequent I3, information b indicating whether the peak value is a positive or negative peak is obtained from the zero cross time acquisition circuit ZTS. Then, at I4, the values of t, c, b obtained in this way are set in the buffer registers Tr, C, B in the microcomputer MCP. Each time interrupt processing is performed in this buffer, such time information, peak value information, and information indicating the type of peak are written as one set, and processing for information on each string is performed in the main routine. Is made.

As described above, the electronic guitar 1 according to this embodiment includes the pitch extraction circuit PC, the plurality of low-pass filters LPF, the fret scan unit FS, and the microcomputer MCP.
The pitch extraction circuit PC detects the vibration of the stretched string.
The plurality of low-pass filters LPF classify a plurality of frets on the fingerboard into one or a plurality of groups, and are provided for each of the classified groups, and have a filtering characteristic corresponding to each group.
The fret scanning unit FS detects which one of the plurality of frets has been operated.
The microcomputer MCP filters the vibration signal of the string detected by the pitch extraction circuit PC with a low-pass filter LPF corresponding to the group to which the fret whose operation is detected by the fret scanning unit FS belongs.
Further, the microcomputer MCP executes a process of extracting the pitch of the musical sound to be generated based on the string vibration signal subjected to the filtering process.
Thereby, it is possible to perform a filtering process using a low-pass filter with respect to the detected vibration of the string at a cutoff frequency corresponding to the position of the pressed fret.
Therefore, the pitch extraction in the electronic stringed instrument can be performed more accurately.

A plurality of strings are stretched, and a low-pass filter LPF is provided for each group for each string.
Thereby, since the pitch extraction in each string can be performed accurately, the pitch extraction in the electronic stringed instrument can be performed more accurately.

The low-pass filter is a low-pass filter that performs a filtering process with a cut-off frequency set corresponding to each group.
Thereby, a more appropriate filtering process can be performed for each fret group.

The electronic guitar 1 further includes a plurality of crosstalk reduction units CTR.
The plurality of crosstalk reduction units CTR includes a plurality of frets on the fingerboard that are classified into one or a plurality of groups, provided for each of the classified groups, and a crosstalk coefficient having a value corresponding to each group. Is used to calculate crosstalk in adjacent strings.
As a result, the crosstalk from the adjacent strings in the vibration waveform to be extracted can be reduced by the crosstalk coefficient corresponding to the fret that is pressed in the adjacent strings. Can be done.

In addition, the crosstalk reducing unit CTR has crosstalk coefficients for the adjacent string having a larger string number and a string number having a smaller string number.
As a result, the crosstalk can be reduced using an appropriate coefficient according to the cause of the occurrence of the crosstalk, so that the pitch extraction in the electronic stringed instrument can be performed more accurately.

  In addition, this invention is not limited to the above-mentioned embodiment, The deformation | transformation in the range which can achieve the objective of this invention, improvement, etc. are included in this invention.

  In the above-described embodiment, 22 frets are described as being divided into three of the first to third fret groups FG1 to FG3, but the present invention is not limited to this. That is, the 22 frets may be divided into more fret groups. Further, the cut-off frequency or crosstalk coefficient of the low-pass filter LPF may be set for each fret.

In the above embodiment, the period is extracted from the interval of each zero cross point next to the maximum peak point and the minimum peak point. However, other methods, for example, the time between the maximum peak points and the time between the minimum peak points are used. Period extraction may be performed from the interval. Further, the circuit configuration can be variously changed in accordance with it.
In the above embodiment, the present invention is applied to an electronic guitar (guitar synthesizer). However, the present invention is not limited to this. Any instrument or device of a type that performs pitch extraction and generates an acoustic signal different from the original signal can be applied.

The series of processes described above can be executed by hardware or can be executed by software.
In other words, the configurations of FIGS. 2 and 4 are merely examples, and are not particularly limited. That is, it is sufficient that the electronic guitar 1 has a function capable of executing the above-described series of processing as a whole, and what functional configuration and circuit configuration are used in order to realize this function are particularly shown in FIGS. It is not limited to the example.
In addition, one functional block may be constituted by hardware alone, software alone, or a combination thereof.

When a series of processing is executed by software, a program constituting the software is installed on a computer or the like from a network or a recording medium.
The computer may be a computer incorporated in dedicated hardware. The computer may be a computer capable of executing various functions by installing various programs, for example, a general-purpose personal computer.

  A recording medium including such a program is provided not only to a removable medium distributed separately from the apparatus main body in order to provide the program to the user, but also to the user in a state of being incorporated in the apparatus main body in advance. It consists of a recording medium. The removable medium is composed of, for example, a magnetic disk (including a floppy disk), an optical disk, a magneto-optical disk, or the like. The optical disc is composed of, for example, a CD-ROM (Compact Disk-Read Only Memory), a DVD (Digital Versatile Disc), a Blu-ray Disc (Blu-ray Disc) (registered trademark), and the like. The magneto-optical disk is configured by an MD (Mini-Disk) or the like. In addition, the recording medium provided to the user in a state of being preinstalled in the apparatus main body is configured by, for example, a ROM or a hard disk in which a program is recorded.

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the order, but is not necessarily performed in chronological order, either in parallel or individually. The process to be executed is also included.

  As mentioned above, although several embodiment of this invention was described, these embodiment is only an illustration and does not limit the technical scope of this invention. The present invention can take other various embodiments, and various modifications such as omission and replacement can be made without departing from the gist of the present invention. These embodiments and modifications thereof are included in the scope and gist of the invention described in this specification and the like, and are included in the invention described in the claims and the equivalent scope thereof.

The invention described in the scope of claims at the beginning of the filing of the present application will be appended.
[Appendix 1]
A string vibration detecting means for detecting vibration of the stretched string;
A plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each classified group, and a plurality of filter means having a filtering characteristic corresponding to each group,
Fret operation detecting means for detecting which one of the plurality of frets has been operated;
Filter control means for filtering the vibration signal of the string detected by the string vibration detection means by the filter means corresponding to the group to which the fret whose operation is detected by the fret operation detection means;
Pitch extraction means for executing processing for extracting the pitch of the musical sound to be generated based on the vibration signal of the string filtered by the filter means;
Electronic stringed instrument with
[Appendix 2]
The electronic stringed instrument according to appendix 1, wherein a plurality of the strings are stretched, and the filter means is provided for each of the groups with respect to each of the strings.
[Appendix 3]
The electronic stringed instrument according to appendix 1 or 2, wherein the filter means is a low-pass filter that performs a filtering process with a cutoff frequency set corresponding to each group.
[Appendix 4]
The electronic stringed instrument further includes:
A plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each classified group, and a crosstalk coefficient having a value corresponding to each group is used to cross between adjacent strings. A plurality of crosstalk calculation means for performing a calculation process of talk,
The electronic stringed instrument according to any one of appendices 1 to 3, which includes:
[Appendix 5]
The electronic stringed musical instrument according to appendix 4, wherein the crosstalk calculating means has the crosstalk coefficients individually for the strings having a larger string number and the strings having a smaller string number among adjacent strings.
[Appendix 6]
String vibration detection means for detecting the vibration of the string that is stretched, and a plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each of the classified groups, and corresponding to each group A musical sound control method used for an electronic string instrument having a plurality of filter means having the filtering characteristics, wherein the electronic string instrument is
Detecting which of the plurality of frets has been operated;
Filtering the detected vibration signal of the string by the filter means corresponding to the group to which the detected fret of the operation belongs,
A musical sound control method for executing a process of extracting a pitch of a musical sound to be generated based on the filtered string vibration signal.
[Appendix 7]
String vibration detection means for detecting the vibration of the string that is stretched, and a plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each of the classified groups, and corresponding to each group A computer used as an electronic stringed instrument having a plurality of filter means having the filtering characteristics,
Detecting which of the plurality of frets has been operated;
Filtering the vibration signal of the string detected by the string vibration detection means to the filter means corresponding to the group to which the fret detected by the operation belongs;
Extracting a pitch of a musical sound to be generated based on the filtered vibration signal of the string;
A program that executes

  DESCRIPTION OF SYMBOLS 1 ... Electronic guitar, PG ... Scan pulse generator, FS ... Fret scan part, FDC ... Fret detection circuit, PC ... Pitch extraction circuit, CTR ... Crosstalk reduction part, LPF ... Low pass filter, AMC ... Amplifier circuit, ZCR ... Zero cross point capture circuit, ABS ... Absolute value capture circuit, LA, 210, 220, 230 ... Low pass filter processing unit, SEL ..Selector, FB ... fingerboard, MCP ... microcomputer, IC ... interrupt control circuit, TMR ... timer, A / D ... analog-digital conversion circuit, MEM ... memory, SOB ... sound source generator, SS ... sound source, D / A ... digital-analog conversion circuit, AMC ... amplifier circuit, DCD ... address decoder, 110 ... lower coefficient selection , 120, 140... Multiplication unit, 130... Upper coefficient selection unit, 150... Addition unit, 111 to 113, 131 to 133 .. coefficient storage unit, R1, R2. C5: Capacitor, OP1, OP2: Operational amplifier, CMP: Comparator

Claims (7)

A string vibration detecting means for detecting vibration of the stretched string;
A plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each classified group, and a plurality of filter means having a filtering characteristic corresponding to each group,
Fret operation detecting means for detecting which one of the plurality of frets has been operated;
Filter control means for filtering the vibration signal of the string detected by the string vibration detection means by the filter means corresponding to the group to which the fret whose operation is detected by the fret operation detection means;
Pitch extraction means for executing processing for extracting the pitch of the musical sound to be generated based on the vibration signal of the string filtered by the filter means;
Electronic stringed instrument with   The electronic stringed instrument according to claim 1, wherein a plurality of the strings are stretched, and the filter means is provided for each of the groups with respect to each of the strings.   The electronic stringed instrument according to claim 1, wherein the filter unit is a low-pass filter that performs a filtering process with a cutoff frequency set corresponding to each group. The electronic stringed instrument further includes:
A plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each classified group, and a crosstalk coefficient having a value corresponding to each group is used to cross between adjacent strings. A plurality of crosstalk calculation means for performing a calculation process of talk,
The electronic stringed instrument according to any one of claims 1 to 3.   The electronic stringed instrument according to claim 4, wherein the crosstalk calculating unit individually has the crosstalk coefficients for the side having a larger string number and the side having a smaller string number among adjacent strings. String vibration detection means for detecting the vibration of the string that is stretched, and a plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each of the classified groups, and corresponding to each group A musical sound control method used for an electronic string instrument having a plurality of filter means having the filtering characteristics, wherein the electronic string instrument is
Detecting which of the plurality of frets has been operated;
Filtering the detected vibration signal of the string by the filter means corresponding to the group to which the detected fret of the operation belongs,
A musical sound control method for executing a process of extracting a pitch of a musical sound to be generated based on the filtered string vibration signal. String vibration detection means for detecting the vibration of the string that is stretched, and a plurality of frets on the fingerboard are classified into one or a plurality of groups, provided for each of the classified groups, and corresponding to each group A computer used as an electronic stringed instrument having a plurality of filter means having the filtering characteristics,
Detecting which of the plurality of frets has been operated;
Filtering the vibration signal of the string detected by the string vibration detection means to the filter means corresponding to the group to which the fret detected by the operation belongs;
Extracting a pitch of a musical sound to be generated based on the filtered vibration signal of the string;
A program that executes

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