JPH0431598B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a waveform signal input control device for electronic musical instruments such as electronic guitars.

[Background of the Invention] Conventionally, pitch (frequency) is extracted from a waveform signal generated by playing a natural musical instrument, and a sound source device composed of an electronic circuit is controlled to artificially produce sounds such as musical sounds. Various devices have been developed to achieve this goal.

In this type of electronic musical instrument, it is common to extract the pitch of an input waveform signal and then instruct the sound source device to generate a scale tone corresponding to the pitch.

By the way, conventional devices of this type detect whether or not the string is vibrating using an electric signal representing the string vibration, and perform sound generation processing and silencing processing. If you perform a picking operation while the string is vibrating, no sound processing will be performed, and therefore the sound generated from the electronic instrument will not change in any way, making the performance unnatural. I was getting used to it.

[Object of the Invention] This invention was made in view of the above circumstances, and it is an object of the present invention to improve the performance effect by changing the output musical tone to follow the performance operation using fast tremolo playing technique or the like. It is an object of the present invention to provide a waveform signal input control device as described above.

[Summary of the Invention] That is, in order to achieve the above object, the present invention temporarily stores a digital waveform signal obtained by digitizing an input waveform signal in a temporary storage means at the peak timing of the positive side or the negative side of the input waveform signal. I will remember,
When a musical tone is generated in response to an input waveform signal, a change in the level of the digital waveform signal is detected by determining the level difference or ratio between the current and previous peak timings of this digital waveform signal, When this level difference or ratio exceeds a predetermined value, the detecting means determines that the peak value of the input waveform signal is rapidly increasing, and according to the determination result of the detecting means, the indicating means The main point is that when a sudden increase in the peak value of the input waveform signal is detected, the musical tone being generated is once muted, and then a command is outputted to start generating it again.

According to this invention, changes in peak values can be detected by a digital circuit, such as a CPU, and the generation control of musical tones that follows performance operations such as tremolo playing can be performed with a small-scale circuit configuration and with stable operation and high accuracy. This means that it can be realized.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Overall circuit configuration Figure 1 shows the overall circuit configuration of the same embodiment. In this embodiment, the present invention is applied to an electronic guitar, and the signals of the six input terminals 1 are transmitted to the electronic guitar body. This signal comes from a microphone or pickup that converts the vibrations of the strings into electrical signals, which are installed on each of the six strings strung on the string.

The musical tone signal from the input terminal 1 is amplified by each amplifier 2 in the pitch extraction circuits P1 to P6 (the figure shows the internal configuration of only the first string P1), and then passed through a low-pass filter. (LPF) 3... cuts high frequency components and extracts the basic waveform, and maximum peak detection circuit (MAX)
4..., minimum peak detection circuit (MIN) 5... and zero cross point detection circuit (Zero) 6... As shown in FIG. 2, the cutoff frequency of the low-pass filter 3 is set to 4f, which is four times the vibration sound frequency f of the open string of each string. This is based on the fact that the frequency of the output sound of each string is within two octaves. The maximum peak detection circuit 4... detects the maximum peak point of the musical tone signal, and at the rising edge of the detected pulse signal, the Q output of the flip-flop 14 connected to the subsequent stage is detected.
It becomes High level, and this flip-flop 14
The AND output of the output of ... and the inverted output of the inverter 30 of the zero-crossing point detection circuit 6 ... is an interrupt command signal via the AND gate 24 ...
INT _a 1 to INT _a 6 are applied to the CPU 100, and similarly, the minimum peak detection circuit 5... detects the minimum peak point of the musical tone signal, and at the rising edge of the detection pulse signal, the flip-flop 15 connected to the subsequent stage... The Q output of... becomes High level, and the AND output of the output of this flip-flop 15... and the output of the zero cross point detection circuit 6... is sent to the interrupt command signal INT _b 1~ via the AND gate 25...
Given to CPU100 as INT _b 6.

That is, when the maximum peak point is detected and the flip-flop 14 is at a high level, when the waveform crosses from positive to negative, an interrupt command signal is generated.
INT _a 1 to INT _a 6 are given to the CPU 100, and the minimum peak point is detected and the flip-flop 15 is
When the waveform changes from negative to positive while at High level, interrupt command signal INT _b 1~
INT _b 6 inputs to CPU100.

Immediately after receiving these interrupt signals, the CPU 100 activates the corresponding flip-flop 14...
Clear signals CL _a 1 to CL _a 6 for ..., 15...
CL _b 1 to CL _b 6 are generated and reset. Therefore,
No matter how many times the zero cross point is passed until the next maximum peak point or minimum peak point is detected, the corresponding flip-flops 14, 15, .

Then, in the CPU 100, an interrupt command signal INT _a 1 to INT _a 6 or
When INT _b 1 to INT _b 6 are given and the respective time intervals Tn and tn are determined, a scale tone according to the time intervals is generated. At the beginning of sound generation, it is possible to start generating scale notes for open strings and correct the frequency after the pitch axis is output, or use the above value.
If Tn and tn (T ₁ and t ₁ at the start of sound generation) match within a certain tolerance range, scale tones may be generated according to the time interval.

The above time interval is determined by the counter 7, the maximum time memory 101, and the minimum value memory 1, as will be described later.
02. That is, the maximum memory 10
The count value of the counter 7 at the zero cross point immediately after the maximum peak point is stored in memory 1 at the minimum time.
02 stores the count value of the counter 7 at the zero cross point immediately after the minimum peak point, and the difference between the previous stored value and the current extracted value is determined by the time interval Tn and tn.
It becomes.

After the start of sound generation, the frequency of the musical tone being generated is variably controlled in accordance with the time interval data (Tn, tn) determined sequentially. That is, the data specifying the scale from the CPU 100 (the above time interval data Tn, tn
corresponds to ) is sent to the frequency ROM 8, and as a result, frequency data indicating the corresponding frequency is read out, sent to the sound source circuit 9, a musical tone signal is generated, and the sound signal is outputted from the sound system 10.

Further, the musical tone signal from the low-pass filter 3... is given to the A/D converter 11...
It is converted into digital data according to the waveform level.

Then, the output of the A/D converter 11 is latched into a latch 12. This latch 12...
The latch signal for... is the output of the flip-flop 14..., 15... from the OR gate 13...
Each time the signal passes through the maximum peak point or the minimum peak point, the latch 12 stores a signal indicating the level of the waveform at that time. Furthermore, the latch signals L1 to L6 from the OR gates 13 are also given to the CPU 100.

The output from the latch 12 is then given to the CPU 100, and controls such as start and stop of sound generation, and the output level (volume) of the output sound are performed in accordance with this data. Note that the peak value stored in this latch 12 is the wave height value (as described later, the maximum peak point is
an, the minimum peak point is bn) is the peak value memory 10
4 are sequentially written.

And for CPU100, A/D converter 11
When the absolute value of the data indicating the waveform level given by ... exceeds a predetermined certain value, the sound generation starts, and when this data falls below the certain value, a mute instruction is issued. End the sound emission. The details of the operation will be described later.

In addition, in FIG. 1, the A/D converter 11 is
Although the pitch extraction circuits P1 to P6 are provided independently, it is of course possible to use one A/D converter in a time-division manner.

The maximum time memory 101, the minimum time memory 102, the frequency ROM 8, and the sound source circuit 9
A six-channel musical tone generation system is formed by time-division processing.

maximum peak detection circuit 4, minimum peak detection circuit 5,
Configuration of Zero Crossing Point Detection Circuit 6 FIG. 3 shows a specific configuration of the maximum peak detection circuit 4. The musical tone signal from the low-pass filter 3 is input to the + terminal of the operational amplifier 4-1, and The output terminal of is connected to the anode side of the diode D1, and the cathode side of the diode D1 is connected to the capacitor C and the resistor R connected in parallel.
1 and grounded through the operational amplifier 4-
1, and the output of the operational amplifier 4-1 is connected to the - terminal of the operational amplifier 4-1 via the resistor R2 and the inverter 4-2.
It is output as a clock signal to the flip-flop 14.

Assuming that a waveform from the low-pass filter 3 as shown in FIG. A waveform like that shown in Figure 4b is input to the - terminal of operational amplifier 4-1, and only when the waveform level rises, +
The difference value between the terminal and the - terminal is output, and this is the signal shown in FIG. 4c. This pulse-like signal shown at c is inverted by the inverter 4-2 and becomes an output as shown at d, which is set by the flip-flop 14 at the subsequent stage at its rising edge, and a latch signal is applied to the latch 12.

Further, the maximum peak detection circuit can also be constructed as shown in FIG. Note that the same parts as those in FIG. 3 are given the same reference numerals. That is, there is a diode D2 connected in the opposite direction to the diode D1 in FIG. 3, and an operational amplifier 4-3 is connected to the + terminal of the operational amplifier 4-1, and the input signal in
is applied to the - terminal of the operational amplifier 4-3 via a resistor R4, and its output is returned to this - terminal via a resistor R3. Further, a buffer 4-4 is provided in place of the inverter 4-2. The operation of the maximum peak detection circuit 4' shown in FIG. 5 is almost the same as the operation of the minimum peak detection circuit 5 described below, except that an operational amplifier 4-3 for signal inversion is connected to the input side. Omitted.

FIG. 6 shows a specific configuration of the minimum peak detection circuit 5, which is almost the same as the maximum peak detection circuit 4, but with a diode D2.
A buffer 4-4 is provided in place of the inverter 4-2, and the capacitor C repeats charging and discharging in the opposite direction as shown in FIG. At the rising edge of the signal as shown, the flip-flop 15 at the subsequent stage is set and a latch signal is applied to the latch 12.

FIG. 7 shows a specific configuration of the zero-crossing point detection circuit 6, in which a waveform signal from the low-pass filter 3 is applied to the + terminal of the operational amplifier 6-1.
A ground level is connected to the - terminal, and the output of the operational amplifier 6-1 is outputted via a resistor R5 and an amplifier 6-2. Therefore, when there is a positive level input signal, the amplifier 6-2 outputs High, and when there is a negative level input signal, the amplifier 6-2 outputs High.
Low output. In other words, the output level is inverted each time the zero cross point is passed.

Operation Next, the operation of this embodiment will be explained. FIG. 8 shows the main flow of the CPU 100. Although this figure 8 only shows the processing for one string, the processing for all strings is exactly the same, so the CPU 100
It may be considered that the process shown in FIG. 8 is executed time-divisionally for each string. First, perform the initial settings in step A1 of Fig. 8, and then proceed to step A.
At step 2, it is determined whether sound is being generated or not, and if it is, the process advances to step A3 to perform processing such as changing the frequency based on the above-mentioned time interval data tn and Tn, and then returns to step A2.

If a negative determination is made in step A2, processing for muting the sound, such as initializing each register or sending a predetermined command to the sound source circuit 9, is executed in step A4, and then step A4 is performed. Return to A2.

Now, the operation when a certain string is manipulated will be explained in more detail as follows. That is, when the input waveform rises due to the string operation and an output is obtained from the low-pass filter 3 as shown in FIG. 4. Corresponding outputs are obtained from the minimum peak detection circuit 5. Also, as shown in g in the same figure, the latch 12 is connected to the A/D converter 1.
An output of 1 is obtained.

When the interrupt command signal INT _a is applied from the AND gate 24 for the first time after half a period of the input waveform shown in the figure has passed, the interrupt process shown in FIG. 10 is executed.

That is, first, in step B1, the peak value (that of the maximum peak point) is fetched from the latch 12, and that value is fetched. Then, in step B2, the flip-flop 14 is reset. For this operation, please refer to the time chart of the interrupt command signal INT _a in FIG. 9e.

Then, the counter 7 at this timing is taken into a predetermined area of the maximum time memory 101 (step B3). Then, in step B4, the peak value a _R (in this case a ₁ ) taken in in step B1 is
is larger than the reference value M.

Now, the above-mentioned wave height value _a1 is large enough and if a YES judgment is made in this step B4, the next step B is started.
5, the value of k (actually, there is an area for storing k, etc. in the work memory in the CPU 100) is incremented. Since k was currently 0, k=1 in step B5.

Then, in the next step B6, it is determined whether k is 1 or not. Since the answer is YES now, step B7
The wave height value a ₁ extracted in step B1 above
is stored in the peak value memory 104. Then return to the main flow.

Next, when the zero cross point after the negative peak point (its peak value b ₁ ) has elapsed, an interrupt command signal INTb is generated as shown in FIG. 9f, and this time the 11th
Execute the interrupt processing shown in the figure. In addition, this 11th
The processing in the figure is almost the same as that in FIG. 10, so a brief explanation will be provided.

First, in step C1, the above-mentioned peak value b1 is taken in, and in step C2, the flip-flop 1 is taken in.
5 is cleared, and in the next step C3, the value of the counter 7 is recorded in the minimum time memory 102. Next, in step C4, it is detected whether or not the peak value b1 is larger than the reference value M. Now b1 is also large enough and a YES jump is made, and the process then proceeds to step C5, where the value of m is incremented. As a result, m=1.

Then, the process advances to step C6, and then to step C7, where the value of b1 is stored in the peak value memory 104.
write in the specified area.

Next, when the interrupt command signal INta is generated and the interrupt processing shown in FIG. 10 is started again, the value of _a2 is taken in at step B1, and steps B2, B3, B4, and B5 are executed in the same manner as above. Then, set K to 2 and proceed to step B8. Since K=2,
Make a YES decision and proceed to step B9.

In step B9, the above-mentioned m (now m=1) and k (now k=2) are compared. This is to judge which of the interrupt processing INTa (Fig. 10) and the interrupt processing INTb (Fig. 11) is performed first, and as mentioned above, the processing based on INTa (that is, the waveform changes in the positive direction first). ), and the judgment in step B9 is
Since k≦m is not satisfied, that is, k>m, the result is NO and the process proceeds to step B10.

In this step B10, the maximum memory 101
The time Tn (currently n=1) in FIG. 9e is obtained by subtraction processing from the two time data stored in , and the musical tone frequency whose period is _T1 is obtained.
Actually, it is determined which fret of the string is being operated.

Then, in step B11, the frequency ROM is set to start generating musical tones corresponding to the above-mentioned frequency.
8. Give a predetermined instruction to the sound source circuit 9 to execute sound generation start (note ON) processing. FIG. 9h shows this state. Therefore, musical tones are generated from this point on.

Then, step B7 is executed and the process returns to the main flow.

Next, upon detection of the zero cross point immediately after the minimum peak point (peak value b ₂ ), the interrupt process shown in FIG. 11 is executed. That is, steps C1→C2→C3→C
Execute 4→C5→C6. As a result, m=2, and the process advances to step C9. And this time m=
Since K=2, in other words, as mentioned above, the sound generation start processing is performed at step B11, so the determination of YES is made at step C9, and no sound generation start processing (steps C10 and C11) is performed. Proceed to the main flow via step C7.

Now, when the next interrupt processing INTa is performed, the peak value _a3 is taken in (step B3), steps B2→B3→B4→B5→B6→B8 are executed, and now k=3, so step B8 is executed. Then proceed to step B12. In other words, in step B8, it is determined whether or not this is the third or higher interrupt processing INTa.

Then, in step B12, the current wave height ak
It is determined whether the difference between (now a ₃ ) and the previous peak value ak-1 (now a ₂ ), that is, ak-ak-1, exceeds a reference value R. When the string vibrates, it normally attenuates, so ak-1-ak becomes a negative value, and the judgment of the judge B12 is NO, and the process goes to step B13. As will be explained later, when ak-1 < ak due to tremolo playing, etc., ak-ak-1
>R is satisfied, and if YES, that is, relative on, proceed to step B1 for relative on processing.
4. Execute B15. The explanation will be given later.

Then, in this case, the process returns to the main flow via step B13 (this is the same as step B10) and B7.

Similarly, when the next interrupt processing INTb arrives, processing for the peak value _B3 is performed. That is, steps C1→C2→C3→C4→C5→C6→C
8→C12→C13→C7, and the process ends.

After the sound generation is started in this manner, the process proceeds while appropriate processing such as changing the frequency is executed in step A3.

As shown in Figure 9a, if an operation such as picking the string is performed again before the sound is finished due to tremolo playing, etc., the next zero cross point of the maximum peak (wave height value an + 1) By the interrupt processing at the time of arrival, in step B12,
Since the determination is YES, that is, an+1-an>R, the process proceeds to step B14, where a mute (note OFF) process is once instructed to the sound source circuit 9, and the output sound level is rapidly decreased (step 9). (see figure h).

Then, in the next step B15, k is set to 1 and m is set to O in order to start sounding again, and after executing step B7, the process returns to the main flow.

Then, the next interrupt processing INTb (peak value bn +
In step 1), m=1 is set in step C5, and therefore the process goes from step C6 to step C7 and returns to the main flow.

Next, k=2 is set at step B5 of the interrupt processing INTa (peak value an+2), and the process proceeds from step B8 to step B9, where k (=2)>m (=1), so steps B10 and B11 are executed. , starts generating a musical tone with a frequency corresponding to the already calculated time value Tn.

In this way, the maximum peak value an of the vibration waveform
When +1 exceeds an and the difference exceeds R, the musical tones that have been generated up to that point are once muted, and then the generation of the musical tones can be started again. At this time, the generated musical tone may be assigned to another sound generation channel of the tone generator circuit 9. For example, the volume and tone may also be changed.

In the above example, the case was an+1>an+R, but on the contrary, when the minimum peak value of the waveform increases rapidly (bm+1>bm+R in FIG. 9a), relative-on processing is performed in the same way.

That is, in this case, the above condition is detected in the interrupt process INTb (peak value bm+1) (step C12), note-off processing is performed in the next step C14, and m=1, k=
Set to 0.

Then, the next interrupt processing INTa (peak value am +
In 2), k=1 is set at step B5, the process proceeds from step B6 to step B7, and m=1 in the next interrupt processing INTb (peak value bm+2).
2, K=1, steps C8, C9, C1
At 0 and C11, relative-on processing is performed. The frequency at this time is determined at time tm in FIG. 9f.

Then, when the amplitude value of the input waveform decreases and a NO judgment is made at step B4 (or step C4), the process advances to step B16 (or step C16), and if sounding is in progress, the process advances to the next step B17 (or step C4). In step C17), the CPU 100 instructs the sound source circuit 9 to mute the musical tone, and then sets k and m to 0 for initialization in step B18 (or C18).
Set to . Continuing to step B18, if a negative determination is made in step B16, the process returns directly to the main flow.

As mentioned above, when the waveform input started, the waveform rose (changed in the positive direction), so the interrupt processing in Figure 10 was performed first, but conversely, the waveform first fell (changed in the positive direction). (in the negative direction), the interrupt processing shown in FIG. 11 is executed first. The operation in that case is also the same as that described above, so the explanation will be omitted.

As described above, in this embodiment, the peak value (maximum/minimum peak value) of the input waveform signal increases by R compared to the previously detected peak value.
Even if the waveform suddenly increases, a relative-on process, that is, a process in which the sound is muted once and then sounded again, is performed to cope with string operations such as tremolo playing, thereby improving the playing effect.

In the above embodiment, in steps B12 and C12, it is determined whether or not the waveform has suddenly changed based on the difference between the previous peak value and the current peak value. >S or bk/bk-1>S (S is a predetermined value of 1 or more) to determine whether or not the waveform has changed rapidly, based on the ratio of peak values.

Further, although it is determined whether or not the waveform has changed rapidly by comparing the previous wave height value and the current wave height value, it may be determined by comparing the wave height values two times before and the current wave height.

Furthermore, in the above embodiment, one of the wave height values ak and bk satisfies the above conditions (ak-ak-1>R, bk-bk-1
Relative ON processing was performed by satisfying >R), but both of the above conditions, that is, ak-ak-1>
By satisfying R and bk−bk−1>R,
Relative-on processing may also be performed.

It may also be possible to detect a sudden increase in the peak value during the generation of musical tones by detecting other conditions.

In the above embodiment, the present invention is applied to an electronic guitar, but the present invention is not limited thereto, and pitch extraction may be performed from an audio signal or an electrical vibration signal input from a microphone or the like. , any type of system may be used as long as it generates an acoustic signal different from the original audio signal at a corresponding pitch or scale frequency. Specifically, the invention can be similarly applied to instruments with keyboards, such as electronic pianos, electronic wind instruments, and electronic string instruments, such as violins and kotos.

[Effects of the Invention] As detailed above, the present invention detects a sudden increase in the input waveform signal during the generation of a musical tone by digitizing the input waveform signal at the peak timing of the positive side or the negative side of the input waveform signal. Find the difference or ratio between the current and previous level of the digital waveform signal obtained by By giving a command to start sounding, musical tones can be generated following the actual playing operation, making it possible to cope with tremolo playing techniques, improving performance effects, and reducing the circuit configuration. It becomes possible to increase the scale, stabilize circuit operation, and achieve high precision.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a diagram showing the overall circuit configuration of the same embodiment, and FIG.
Figure 3 is a diagram showing the cutoff frequency of the low-pass filter in the figure, Figure 3 is a configuration diagram of the maximum peak detection circuit, Figure 4 is a diagram showing the operating waveforms of each part of the maximum peak detection circuit and minimum peak detection circuit, and Figure 5. is a circuit configuration diagram showing another example of the maximum peak detection circuit, Figure 6 is a configuration diagram of the minimum peak detection circuit, Figure 7 is a configuration diagram of the zero cross point detection circuit, and Figure 8 is the main flowchart of the CPU. Figure 9 is a time chart showing the input waveform and the operation of each part associated with it, Figure 10 is a flowchart of interrupt processing when detecting a zero cross point immediately after the maximum peak point, and Figure 11 is a time chart showing the input waveform and the operation of each part associated with it.
The figure is a diagram showing a flowchart of interrupt processing at the time of zero-cross check output immediately after the minimum peak point. 1...Input terminal, 4...Maximum peak detection circuit,
5... Minimum peak detection circuit, 6... Zero cross point detection circuit, 9... Sound source circuit, 14, 15... Flip-flop, 100... CPU, 104... Peak value memory, P1 to P6... Pitch extraction circuit.

Claims (1)

[Claims] 1. Peak timing detection means for sequentially detecting peak timings on the positive side or negative side of an input waveform signal, analog-to-digital conversion means for digitizing the input waveform signal, and conversion of the analog-to-digital conversion means. Temporary storage means for temporarily storing the output digital waveform signal at each peak timing detected by the peak timing detection means, and sequentially storing the digital waveform signal in the temporary storage means when a musical tone is generated corresponding to the input waveform signal. A change in the level of the digital waveform signal that is detected is detected by determining the difference or ratio of the level of the digital waveform signal between the current and previous detection peak timing, and this level difference or ratio is determined to be a predetermined value. a detecting means for detecting that the peak value of the input waveform signal is rapidly increasing when the peak value of the input waveform signal exceeds the peak value; A waveform signal input control device comprising: instruction means configured to issue a command to start producing the musical tone again after once silencing the musical tone being generated.