JPS63136088A - Input controller for electronic musical instrument - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Outside the technology of the invention! 71 This invention relates to an input control device for an electronic musical instrument such as an electronic guitar.

[Background of the Invention] Conventionally, it has been attempted to extract pitch (frequency) from a waveform signal generated by playing a natural musical instrument and control a sound source device composed of an electronic circuit to artificially obtain sounds such as musical tones. Various types have been developed.

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 an RF scale tone corresponding to the pitch.

By the way, this type of technology was disclosed in Japanese Patent Application Laid-open No. 5
No. 5-159495, but in this prior art, adjacent cycles of the input waveform are detected, and when the cycles substantially match, a sound generation command is output to the sound source circuit. , a sweating instruction is issued only after detecting a waveform of two or more cycles, and there is a problem in that the response speed from the sound source circuit to the start of musical sound generation is poor.

In particular, the lower the pitch, the longer the wavelength, so it takes longer to extract the pitch, which is a problem with IaO.
It will appear in the book.

[Purpose of the Invention] The present invention was made in view of the above circumstances, and is designed to shorten the time from when a waveform signal is input until actual sound is generated, to improve response, and to improve performance during performance. An object of the present invention is to provide an input control device for a child musical instrument that does not give an unnatural feeling.

[Key Points of the Invention] In other words, in order to achieve the above object, this IIN focuses on the fact that there are three pieces of period information between two periods of the input waveform, and provides information on the period length of less than two periods of the input waveform. The key point is that two periods of the waveform are detected, and if the two periods substantially match, an instruction to start sounding is given.

Specifically, the time interval (1+) of the zero-crossing point that appears for the first time after the maximum value of the input waveform signal is detected, and the time interval (t2) of the zero-crossing point that appears for the first time after the minimum value of the input waveform signal is detected. By doing so, the above 2
Detect two cycles.

Alternatively, the two cycles are detected by detecting the time interval (TI) where the maximum value of the input waveform signal appears and the time interval (T2) where the minimum value of the input waveform signal appears.

In this way, the IJJ from Ichiki shortens the length of time from the arrival of the input waveform signal until the generation of artificial sound, thereby increasing the performance effect.

The characteristics of this 41jll will become clearer from the following explanation of the example IJI.

[Example] Hereinafter, each example of Shukan 11 will be described in detail with reference to the drawings.

First Embodiment Body Circuit Configuration FIG. 1 shows the overall circuit configuration of the first embodiment.
In this embodiment, the present invention is applied to an electronic guitar, and the signals of the six input terminals l are the vibrations of the strings provided on each of the six strings stretched on the electronic guitar body. This is the signal from the pickup that is converted into an upper air signal.

The musical tone signals from the input terminals 1, . ) Each internal amplifier 2.
It is amplified by ... and low pass filter (LPF) 3
The high frequency component is cut off and the basic waveform is extracted in . . . , and the maximum peak detection circuit (MAX) 4...
, a minimum peak detection circuit (MIN) 5 . . . and a zero cross point detection circuit (Zero) 6 . As shown in FIG. 2, the low-pass filter 3 has a cutoff frequency set to 4f, which is four times the vibrational sound frequency fif of the open strings 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 in the subsequent stage is detected. It becomes H1gh level,
The output of this flip-flop 14... and the inverter 30... of the zero cross point detection circuit 6...
The AND output with the inverted output of ... is the AND gate 24.
1, 1 entry command signal ■NTa+- via...
It is transferred to the CPU 100 as an IN Tab.

Similarly, the minimum peak detection circuit 5... detects the minimum peak point of the Raku-Kana Shinkan, 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... Interrupt command signal INT via...
b Provided to the CPU 100 as I to lNTb6.

That is, the maximum peak point is detected and the flip-flop 14
When the waveform crosses from positive to negative while is at High level, the interrupt command signal I N Ta+ ~ I
N Tab is given to the CPU 100, and conversely, when the minimum peak point is detected and the clip flop 15 is at High level, when the waveform changes from negative to positive, the interrupt command signals INTゎ1 to lNTb6 are output. CPU1
Enter 00.

Immediately after receiving these interrupt command signals, the CPU 100 activates the corresponding flip-flops 14...
Clear signal CLa1- for ..., 15...
CLa6. Generate and reset CLb+-CLbb. Therefore, no matter how many times the zero cross point is passed until the 5th maximum peak point or minimum peak point is detected, the corresponding flip-flops 14, 15, . . . are in a reset state. This means that the CPU 100 will not be interrupted.

Then, the CPU 100 uses the vibration output of the string at the start of one sound, as will be described in detail later, to issue a 1-input command I N
Tag~I N Tab or lNTb1~lNTb
6, each time interval E (t + and tz)
Once the values are determined, if the values are approximately equal, the frequency ROM 8 and the sound source circuit 9 are configured to start outputting scale tones according to the values.
Instruct to. This time interval is counted using the counter 7, the maximum memory lot, and the minimum memory 102.

That is, in the CPU 100, when the interrupt command signals lNTa+ to lNTa6 of the zero-cross point immediately after the detection of the maximum peak point are given among the above-mentioned interrupt command signals, the interrupt command signal lNTa+ to lNTa6 at the zero-cross point immediately after the maximum peak point detected in the same manner as before is given. The difference from the counter value of
+ to lNTl+6, the difference from the counter value detected in the same way before then is determined. Both signals rNT
(IN T al ~ I N T a 6, I N T
Each time the count f4 of the counter 7 is changed, the count f4 of the counter 7 is stored in the corresponding maximum time memory 101 and minimum time memory 102, respectively.

The time count data of the difference between the count values of the counter 7 thus obtained becomes the above-mentioned time interval (1+ and tz).

After the start of one sweat, the frequency of the musical tone being generated is variably controlled according to the time interval data (1+ and tz) determined in the same manner as above. ) is sent to the frequency ROM 8, and frequency data indicating the frequency corresponding to the time count data is read out and sent to the a source circuit 9 to generate a musical tone signal, which is emitted from the sound system 10.

The RF signals from the low-pass filters 3 are given to the A/D converters 11 and converted into digital data according to their waveform levels.

The outputs of the A/D converters 11 . . . are latched in the latch 12. This latch 12...
The latch signal for... is the flip-flop 14
......, 15...... output is off gate 1
3..., and each time the maximum peak point or minimum peak point is passed, the latch 12...
. . - stores a signal indicating the level of the waveform at that time. Furthermore, the latch signals from the O7 games) 13, . . . are also given to the CPU 100.

Then, the output of the latch 2 is 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 according to this data.

That is, in the CPU 100, the A/D converter ll...
...When the absolute value of the data indicating the waveform level given by . to end the sound emission.

In FIG. 1, the A/D converter 11 is provided independently in each of the pitch extraction circuits P1"P6, but -
Of course, it is also possible to use the /D converter in a time-division manner.

Then, the maximum memory 101. Minimum memory 102
Furthermore, the frequency ROM 8 and the tone generator circuit 9 form a six-channel musical tone generation system by time-division processing.

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 middle terminal of the operational amplifier 4-1, and the output terminal of the operational amplifier 4-1 is connected to the diode DI. 7 node side, and the cathode side of the diode DI is connected to the capacitor C connected in parallel.
and a resistor R1, and are connected to one terminal of the operational amplifier 4-1, and the output of the operational amplifier 4-1 is transmitted through the resistor R2 and the amplifier 4-2 to receive the interrupt command signal for detecting the maximum peak point. It is output as lNTa1 to INTab.

Assuming that a waveform as shown in Fig. 4(a) is applied to the middle terminal of the operational amplifier 4-1, the capacitor C is charged when the waveform level rises, and discharged when the waveform level falls, and as shown in Fig. 4(a). A waveform like b) is the operational amplifier 4-1.
The difference value between the middle terminal and the first terminal is output only when the waveform level rises, and this is output as the interrupt command signal lNTa shown in FIG. 4(C). Interrupt processing is started at the falling point of the pulse-like signal shown in (C).

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 symbols, that is, there is a diode D2 connected in the opposite direction to the diode DI in FIG. 3, and at the middle terminal of the operational amplifier 4-1, The operational amplifier 4-3 is connected, and the input signal in is connected to one terminal of the operational amplifier 4-3 through the resistor R4.
The output is fed back to this one terminal via a resistor R3. The operation of the maximum peak detection circuit 4' in FIG. 5 is almost the same as the operation of the minimum peak detection circuit 5 described in the first section, 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,
This minimum peak detection circuit 5 is almost the same as the maximum peak detection circuit 4, but the direction of the diode D2 is reversed, and the capacitor C is charged and discharged in the opposite direction as shown in FIG. 4(d). return.

An interrupt command signal lNTb as shown in FIG. 4(e) is obtained.

FIG. 7 shows a specific configuration of the zero-cross point detection circuit 6, in which a musical tone signal from the low-pass filter 3 is applied to the middle terminal of the operational amplifier 6-1.

A ground level is connected to one terminal, and the output of this operational amplifier 8-1 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 H4gh, and when there is a negative level input signal, the amplifier 6-2 outputs Low. In other words, the output level is inverted each time the zero cross point is passed.

Next, the operation of this embodiment will be explained. Figure 8 1icP
This is the main flow of Uloo. Although FIG. 8 only shows the processing for one string, the processing for all strings is exactly the same, so it can be considered that the CPU 100 executes the processing in FIG. 8 for each string in a time-sharing manner. ,
First, after performing the initial setting in step AI of FIG. 8, the value of the A/D converter 11 is read in step A2, and the musical tone off processing is continued unless it reaches a certain level (steps A3, A4, . A5). Now, if there is a string playing operation and a musical tone signal of a certain level or higher as shown in Fig. 9(a) is input to the A/D converter (
Step A3), proceed to step A5, I:! : It is judged whether the time intervals t1 and t2 extracted in , match. However, since the interval between both grips has not yet been detected, a negative determination is made in step A6, and the process returns to the original flow. Furthermore, as will be described later, when starting to produce sound, the process proceeds to step A7 and the time U old mWt+ (-
t2) starts generating musical tones of the scale. After that, steps A3-A4. Proceeding to A8, in this step A8, frequency control processing, that is, musical tone emitting processing for giving data specifying a musical scale to the frequency aROM 8, is performed.
This sound emitting process continues as long as the musical tone signal level is above a certain level (steps A2→A3→A4→A8), and when the output level of the A/D converter 11 becomes below a certain value, step A5 is executed. Start muting.

Now, the operation when a certain string is manipulated will be described in more detail as follows. That is, the musical sound waveform rises due to the string operation, and reaches the first maximum peak point (
The waveform level reaches MAXI in the figure, the maximum peak detection circuit 4 generates a signal as shown in FIG. 9(b), and the flip-flop 14 goes high ((
d)), and the zero-crossing point detection output from the zero-crossing point detection circuit 6 is Zer in FIG. 9(a).

When it is reversed at point 1 (see 5(C) +!!), the AND gate 24 sends an interrupt command signal I to the CPU 100.
N Ta (I N Tal - I N Ta6) is changed, and the CPU 100 starts the interrupt processing shown in FIG. 1θ. First, the CPU 100 resets the flip-flop 14 and reads the count value of the counter 7 in step B1, and then determines whether the waveform is the first wave or not in step B2. The musical sound waveform has just started,
Since this is the first wave, the process proceeds to step B5, sets flag rlJ, and sets the count value of counter 7 read out in step Bl in the maximum time memory 101. This flag rlJ is a flag indicating that the next zero-crossing point after the maximum peak point has already been detected, and if this flag is cleared, it indicates that the minimum peak point has been detected. Note that the function of this flag will be described later.

Now, if a waveform like that shown in Figure 9(a) is input,
Next, zero cross point Zero2. Each time Zer03 is detected, an inverted output is obtained from the zero cross point detection circuit 6 as shown in FIG.

However, the output of the flip-flop 14 has been reset (at step B1), and no interrupt command signal lNTa is generated.Of course, the flip-flop 15 also remains reset, so the interrupt command signal Nl
Tb is not generated.

Next, when the minimum peak point indicated by MINI in FIG. 9(a) is reached, the minimum peak detection circuit 5 outputs a peak detection signal, and the flip-flop 15 is set. Then, at the next zero-crossing point (Zero4), the output of the zero-crossing point detection circuit 6 is inverted, and as a result, the AND gate 25 sends an interrupt command signal N to the CPU 100.
I T b is applied, and the CPU 100 starts the interrupt processing shown in FIG. First, the CPU 100 performs step C
1, the flip-flop 15 is reset, the count value of the counter 7 is read, and it is determined whether the waveform is the first wave (step C2), but for the zero cross point after the minimum peak point, in this case it is the first wave. Therefore, step C
5, the flag is cleared to "0" and the count value of the counter 7 read out in step CI is set in the minimum time memory 102.

The determination as to whether or not this is the first wave in step C2 and step B2 is made, for example, when the waveform level data from the A/D converter 11 exceeds a certain level.

Set the first wave flags A and B, and when the interrupt command signal IN"l for detecting the zero cross point immediately after the maximum peak point is given, after step B2 and before step B5, clear the first wave flag A, Step C when the interrupt command signal lNTb for detecting the zero cross point immediately after the minimum peak point is given.
This is achieved by clearing the first wave flag B after step 2 and before step C5, and determining whether or not the first wave flags A and B are set in steps B2 and C2. 'When the zero-crossing point (Zero5) following the maximum peak point shown in MAX2 in FIG. 9(a) is reached, an interrupt command signal lNT for detecting the zero-crossing point immediately after the maximum peak point is generated.
a is given, the CPU 100 reads the count (6) of the counter 7 in step Bl, determines that the waveform is no longer the 1st wave in step B2, and determines whether the flag is rOJ in step B3. The next zero crossing point (Zer.

Since rOJ is reached in step 4), the CPU 100 proceeds to step B4, reads out the time count data set in the memory 101 at the maximum at the zero cross point (Zerol) immediately after the maximum peak point MAX1 one cycle before, and returns the time count data to step B1. The result data is 1+ (Figure 9(e)).
).

Following the above processing, cptrioo sets the flag rl
J is set and the current time count data value is set in the maximum time memory 101 (step B5).

In this way, in steps C5 and B3, the zero-crossing point immediately following the green peak point is determined, the time (1+) between these zero-crossing points is measured, and the cycle is calculated in step B4.

Similarly, the zero-crossing point (Zero6, Zero) is ignored and the zero-crossing point (Zero6, Zero) immediately after the minimum value detection
8) In response to the input of the interrupt command signal lNTb from the AND gate 25, the CPU 10
0 performs the processing shown in the flow shown in Figure 11, and this time it moves from the previous zero-crossing point (Zero4) to the current zero-crossing point (Zero4).
The time m1 interval (t2) up to Zero8) becomes pitch extraction data.

After this zero cross point (Zero 8) is detected, the process returns to the main flow and executes step A6 following step A3 in FIG. Here, the above time data 1
．． When and t2 match within a certain false gs range, the judgment result in step A6 is YES, and as described above, in step A7, the generation of a musical tone with a frequency corresponding to the length of t2 according to tl is started. (See Figure 9(f)).

Then, if the judgment in step A6 is No, that is,
Time L of the above-mentioned zero cross point Zero-Zero5
1 and the time t of zero cross points Zero4 to Zero8
If 2 is different, the process waits for the next interrupt processing without starting sound generation.

In other words, from Zero4 to Zero8 +1iT lb'l
The interval t2 and the first-order Zer05 to Zer09 (Fig. 9(a)
In step A6, it is determined again whether or not the time interval t1 of the time interval t1 of the time interval t1 of the scale is substantially the same.If YES, the process proceeds to step A7, and the generation of the musical tone of the relevant scale is instructed.

After that, calculate the time interval (1+) between the zero-crossing points that occur immediately after the maximum value is detected, and the time interval (E2) between the zero-crossing points that occur immediately after the minimum value is detected, and adjust them as necessary. The frequency change process is performed twice in a period, so it is possible to respond to changes in the frequency of the input signal.

By the way, in this embodiment, - the above-mentioned Fig.
:j Even if the waveform shown in Figure 12 is input due to the flag function of the flow in Figure 1, the zero crossing point Z in the figure
ero12 and Zero4 will be ignored.

In other words, even if signals corresponding to zero cross points Zero12 and Zero4 are input as the interrupt command signal lNTa, the flags are set to zero cross points Zero11. Zero
It was set to 1 when 13 arrived (step B5)
, Therefore, the judge in step B3 becomes NO, and no periodic calculation is performed. In this way, in this embodiment, by using this flag, even if a zero crossing point is detected multiple times in succession after the maximum value or minimum value is detected, it is ignored, thereby making it possible to further remove the influence of overtones. There is.

Now, in all of the above examples, the waveform rises first. That is, the case where the amplitude value increases in the positive direction from the zero level is input, but the same operation occurs when the waveform first falls, that is, the amplitude value increases in the negative direction from the zero level.

:513 shows an example of such a case, and the same figure (
When a waveform like that shown in a) comes in, the output of the zero cross point detection circuit 6 becomes like that shown in the same figure (b), and as a result, CP
For U100, an interrupt command signal lNTb is first generated, and from that point on, the processing shown in the flowchart of FIG. 11 is performed.

It starts counting time t2 (see zero cross point Zero21 in the same figure (a)), and after that, the zero cross point immediately after the maximum peak point (see the zero cross point Zero21 in the same figure (a))
22), the interrupt command signal lNTa is generated, and the first
The process shown in the flowchart in Figure 0 is started, and at the next zero-crossing point (Zero 23 in Figure (a)), the first cycle calculation is completed and time t2 is obtained, and at the next zero-crossing point ( Time t1 is obtained at Zero24) in FIG.

After completing the process shown in FIG. 10, which is the interrupt process for this zero cross point Zero24, the process returns to the main flow process shown in FIG. 8, and steps A3 and A6 are executed.

Then, in step A6, 1iiJ t 2 and t
) (see FIG. 13(C)) within a certain tolerance range, and if the result is YES, step A7
As shown in FIG. 13(d), the CPU 100 instructs the frequency ROM 8 and the tone generator circuit to generate a scale tone having a period indicated by that time.

If the judgment result in step A7 is NO, the next time t2 (starts from zero cross point Zero23) and the already obtained time 1+ (starts from zero cross point Zero23)
22 to Zero 24) after about half a cycle, and when both times substantially match, the process of starting sound generation is performed as described above.

In this way, even if the waveform falls,
The turning part is to start sounding within less than a cycle (1.5 cycles in the case of a sine wave).

In addition, after starting the previous memorized pronunciation as the process in step A8 of FIG. 8, the average value of the time count data and the time count data obtained this time is taken and output, or When the data difference is large, for example, if the difference is 20% or more, the previous data is output, and stability of one frequency can be achieved. In addition, after the start of sound generation, the period calculation based on the detection of the zero cross point immediately after the maximum peak point and the period calculation based on the detection of the zero cross point immediately after the minimum peak point are performed. Performs period calculation only based on the zero-crossing point immediately after the peak point, and if the starting point of the musical waveform is a falling waveform, selectively performs period calculations based on the zero-crossing point immediately after the minimum peak point. You can do it like this.

In this way, in this embodiment, the CPU 100
An appropriate process can be executed as the process of step A5 shown in the figure, and since this process can be changed by directly changing the program of the CPU 100 without changing the external circuit of the CPU 100, versatility is increased.

Note that in the above embodiment, step B4 in FIG.
The cycle is calculated in step C4 of Figure 1, and the sound production control and music B frequency control based on this cycle calculation are performed in step A7 or A8 in the main flow of Figure 8. It can also be done during the import process. Interrupt processing like that (Figure 1θ, Figure 11)
Among these, the responsiveness to the input signal is better when the sound generation start processing and the frequency change processing are performed.

Second embodiment circuit configuration and operation Next, a second embodiment of the present invention will be described.

This second embodiment is based on the time interval (T
1) and the time interval (T2) between the minimum peak points to perform sound generation control, and FIG. 14 shows the overall circuit configuration.

That is, the outputs of the microphone and the piper 2 are given to the input terminals 201, and the outputs thereof are supplied to the pitch extraction circuit pH-PI3.

The specific configuration of the pitch extraction circuit Fil-P16 is as shown in the pitch extraction circuit pH. First, an amplifier 202 receives the output from the input terminal 201.
. . . The output is received through a low-pass filter 203 . . . that cuts high-frequency components appropriately, and a maximum peak detection circuit (MAX) 204 . . . 0 detects the minimum peak. It is commonly applied to the circuit (MIN) 205 . . . and the A/D converter 206 .

The specific circuit configurations of these maximum peak detection circuits 204, minimum peak detection circuits 205, and so on can be those of those circuits in the first embodiment.

Now, these maximum peak detection circuits 204...
, minimum peak detection circuit 205..., A/D converter 206..., outputs are input to the CPU 200, and the time interval (TI) between the maximum peak points and the time between the minimum peak points are input to the CPU 200. The interval (T2) is detected by the internal processing of the CPU 200, and the sound generation start processing 1 frequency change processing is performed.

FIG. 15 shows a time chart when the input waveform signal rises. When the waveform comes in as shown in (&) in the figure, the maximum peak detection circuit 204 output will be as shown in (b) in the figure. The output of the minimum peak detection circuit 205 is shown in the same figure (c
).

Therefore, the CPU 200 calculates each time TI and T2 based on the respective detection outputs as shown in FIG. As shown in (e), a sound generation start command is output to the Otohime circuit.

If the above time TI and T2 do not match, the newly obtained TI after about half a cycle and the already obtained TI
If they substantially match, the sound generation start process can be performed from that point.

As described above, the present invention can be used in various ways as a method for extracting the pitch. and the time interval (tl) of the zero crossing point that appears for the first time after detecting the minimum value, or the time interval (tl) at which the maximum value of the input waveform appears as shown in the second embodiment. In addition to the method of matching and comparing the time interval (T2) in which .

For example, the present invention can be similarly applied to a method of detecting pitch from a simple time length between zero-crossing points, a method of detecting pitch by determining periodicity by calculating an autocorrelation function or other function of a waveform, and the like.

In any case, the present invention provides three periodic information between two periods of the input waveform. Wt+ , tz , t+ or tz, t
+, tl (in the case of the first embodiment), or TI, T
2, TI or T2, TI, T2 (in the case of the second embodiment), the waveform has two periods within less than two periods (1.5 periods in the case of the perfect sine method) of the input waveform. Upon detection, if the two values match within a permissible range, an instruction is given to the sound source circuit to start generating sound.

In the above embodiments, the present invention is applied to an electronic guitar, but the present invention is not necessarily limited to this, and the present invention can be applied to pitch extraction from a voice signal or an electrical vibration signal input from a microphone or the like. ,r For example, electronic piano, /i? The present invention can be similarly applied to electronic musical instruments and electronic stringed instruments such as violins and kotos.

[Effect of oscilloscope] As described in detail below, this invention detects two periods of an input waveform signal within a time length of less than two periods of the input waveform signal, and detects if the two periods are approximately equal. For example, by instructing the production of a musical tone with a frequency corresponding to the cycle, the time from when the waveform signal is input to when sweating actually starts can be shortened, the response can be improved, and there is no problem when playing. This has the advantage that it no longer feels natural.

[Brief explanation of the drawing]

1 to 13 show a first embodiment of the present invention;
2 shows the cutoff frequency of the low-pass filter in FIG. 1, FIG. 3 shows the configuration of the maximum peak detection circuit, and FIG. 4 shows the overall circuit configuration of the same embodiment. , a diagram showing the operating waveforms of each part of the maximum peak detection circuit and the minimum peak detection circuit, FIG. 5 is a circuit configuration diagram showing another example of the maximum peak detection circuit, FIG. 6 is a configuration diagram of the minimum peak detection circuit,
Figure 7 is a configuration diagram of the zero cross point detection circuit, Figure 8 is the CP
Figure 9 is a diagram showing the main flowchart of U. Figure 9 is a time chart diagram showing the input waveform and the operation of each part associated with it.
Figure 0 shows an interrupt processing flowchart when a zero crossing point is detected immediately after the maximum peak point, Figure 11 shows an interrupt processing flowchart when a zero crossing point is detected immediately after the minimum peak point, and Figure 12 shows another input waveform. A time chart diagram showing the operation of each part accompanying this, FIG. 13 is a diagram showing a time chart of each part when the input waveform falls;
14 and 15 show a second embodiment of the present invention, FIG. 14 is a circuit diagram thereof, and FIG. 15 is a diagram showing a time chart of the same embodiment. 1.201... Input terminal, 4.204...
... Maximum peak detection circuit, 5.205 ... Minimum peak detection circuit, 6 ... Zero cross point detection circuit, 7 ... Counter, 8 ... Frequency R.O.
M, 9...Sound source circuit, lO...Sound system, 14.15...Free. Pflop, 1OO1200...CPU, 10
1... Maximum time memory, 102... Minimum time memory, P1 to P6, pH to P16... Pitch extraction circuit. Patent Applicant Casio Computer Co., Ltd. Agent Patent Attorney Machi 1) Masaru Toshi' --2Σ-j ShiYL [l F&a/)Flll嘗$! T +c7F-)t
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Claims (3)

[Claims] (1) A detection means for detecting two periods of the input waveform signal within a time length of less than two periods of the waveform when inputting the input waveform signal, and the above two periods detected by this detection means. 1. An input control device for an electronic musical instrument, comprising: an instruction means for instructing generation of a musical tone having a frequency corresponding to the two periods when the two periods are substantially equal. (2) The detection means detects the time interval (t_1) of the first zero crossing point after the maximum value detection of the input waveform signal.
) and the time interval (t_2) of a zero-crossing point that appears for the first time after detecting the minimum value of the input waveform signal, thereby detecting the two periods. The input control device for an electronic musical instrument according to item 1. (3) The detection means detects the time interval (T_1) at which the maximum value of the input waveform signal appears and the time interval (T_2) at which the minimum value of the input waveform signal appears, thereby detecting the two periods. An input control device for an electronic musical instrument according to claim 1, characterized in that the input control device for an electronic musical instrument is configured to detect.