JPS5913038B2 - Beat effect generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bead effect generating device that generates a bead effect using a transfer type delay device such as a charge transfer element.

25 Conventionally, in order to generate a bead effect, it is common to mix multiple sound source signals with slightly different frequencies, but in this case, it is necessary to provide multiple sound source signals, so the configuration However, it is also disadvantageous in terms of price.

30 It is also known to convert the frequency of a single sound source, shift it by the bead frequency, and mix it with the original sound to obtain a bead effect, but in this case, all harmonics are shifted by the bead frequency. 35, so that the frequency of the mixed sound bead is constant and the same for all harmonics.

For this reason, the bead feeling is concentrated in one frequency, and the effect that the bead frequency becomes larger as the harmonic order of the sound source signal becomes higher cannot be obtained as in the case where a plurality of sound sources are provided. On the other hand, the phase modulation effect has been conventionally achieved by changing the delay time of a charge transfer element such as a bucket brigade device (referred to as BBD) or a charge coupled device (referred to as CCD) using a sine wave modulation signal. There are various methods known to achieve this, but all of these methods only achieve a phase modulation effect and cannot generate a bead effect.

There are also devices that use multiple charge transfer devices to convert the audio playback speed, but this does not change the pitch of the audio, and moreover, the audio information may be truncated. There is a problem in that it cannot be used for music because it tends to generate noise.

The present invention provides a bead effect generating device which solves the above-mentioned problems by generating a bead effect using a transfer type delay device such as a charge transfer element.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 12.

FIG. 1 shows an embodiment of the present invention, in which 1 is an input terminal for musical tone signals of an electronic musical instrument, 2 is a transfer type delay device such as a BBD or CCD, and 3 is an input terminal for an input signal A and the delay device 2. output B
4 is an output terminal for the mixed signal,
5 is a modulation signal generator, 6 is a voltage-controlled clock signal generator, and 7 is a driver circuit that generates two-phase clock signals φ1 and φ2.

Note that the delay device 2, modulation signal generator 5, clock signal generator 6, and driver circuit 7 constitute a phase modulator. In the above configuration, the musical tone input signal A supplied to the input terminal 1 is applied to the delay device 2 and the adder 3.

On the other hand, the modulation signal VM from the modulation signal generator 5 is applied to a voltage-controlled clock signal generator to modulate the clock frequency Fc. Two-phase clock pulses φ1 and φ2 corresponding to the clock frequency Fc are generated from the driver circuit 7, and the input signal A is delayed by the delay device 2 by these clock pulses φ1 and φ2. The output signal B of the delay device 2 is mixed with the input signal A in the adder 3, and a bead sound effect is obtained at the output terminal 4. The above is the basic operation of FIG. 1.Next, individual specific operations will be explained to explain the principle of obtaining the bead sound effect.

The modulation signal generator 5 generates a triangular wave, unlike a conventional sine wave.

In addition, the clock signal generator 6 changes the clock frequency Fc according to a hyperpolicy function with respect to the modulation signal VM from the modulation signal generator 5, or changes the clock frequency Fc in proportion to a reciprocal function of the manual modulation signal M. is configured to do so. This can be expressed numerically as follows. Here, K1 and K2 are constants.

In this way, the clock frequency Fc changes with time t like a hyperpolis function. On the other hand, in order to change the input signal frequency of the transfer type delay device 2 by a certain ratio,
The ratio between the sampling interval at the input and the sampling interval at the output should always be a constant value.

That is, the delay device 2 is set at time T as shown in FIG. ,tl,
t2, ......, TN-1, tN, ...
It is assumed that the signal is sampled at the input, transferred through N stages, and output. In this case, time T. The sample at time T, is output at time TN, and the sample at time T, is output at time TN+1. The sample interval at the input is (t1-TO), and this sample interval becomes (TN+1-TN) when read at the output. Here, t1-TO-τs(TO), TN+1-
If TN=τ8(TN), the ratio τ8(TN)/τ
8(TO) - αN is the reciprocal of the ratio of the input musical tone signal frequency at the input and output. At what time TN is this ratio α?
If it is also made constant, the input/output frequency ratio of the embodiment shown in FIG. 1 becomes constant. Next, from TO to T
The time to N is determined by the sequence of each sample interval τ8(N) as α
Since it becomes a geometric progression, it becomes.

On the other hand, the clock frequency Fc is changed to the sampling interval τs(N
) is defined as follows. Ding Nawachi Fuku JtN Minne σ
○Ic is expressed as the reciprocal of the pulse period T at time TN. When the pulse period is constant, the clock frequency is also constant, so Fc=1. As shown in Fig. 2t, when time TN is the time when a pulse is generated and Ts changes with time, time TN
The pulse periods at are Ts(TN-1) and Ts(
It is appropriate to express the period as an intermediate period of TN).

Considering this, in equation (3), the geometric mean Ts
(TN-1)·Ts(N) is the period at time TN, and the clock frequency Fc(TN) is expressed as the reciprocal of the period expressed by the geometric mean. Note that there are other ways to define it. For example, let us define the clock frequency at time TN as the reciprocal of period Ts(TN)=Fc(TN)=
It is also possible to take the form Ts(TN).

Even in this way, Ts(TN) and Ts(TN-l
), the resulting equations do not differ significantly. For example, Fc (TN) is 50KHZ~100
If it changes between KHZ with a period of 5HZ, then 10
It will change from 50KHZ to 100KHZ in 0ms. There are 5000 KHZ pulses and 10000 100 KHZ pulses in 100 ms.

100KHZ-50K? =50KHZ, 5000~1
Since the transition occurs at an intermediate number of pulses of 0,000, the difference in period between adjacent pulses is approximately 0.02% to 0.01%.

Therefore, you can leave it alone.

Here, τs(TN)/τs(TO)=αN
(TN)=τs(TO)αN, so τS(TN
−1)=τs(TO)αN −1.

So, by substituting these equations into equation (3), we get:

Then, from equation (2), and from equations (4) and (5), becomes.

Here, if t is substituted for TN, it becomes. Therefore(
Comparing Equation 1) and Equation (7), we can see that in Equation (1), the modulation signal VM is a voltage proportional to time like a ramp waveform, VM = K3t... (8) ( However, if K3 is a constant), equations (1) and (7) become equivalent, and it can be seen that the ratio of the input and output frequencies of the delay device 2 becomes a constant value α゜.

Here, when K3 is negative, α is 1, that is, αN is 1, and the pitch increases.

When K3 is positive, α>1, that is, αゞ>1, so the pitch decreases. Leaving K3 as either positive or negative depends on the number of stages of the transfer delay device 2 and the clock frequency F. This is not possible due to the following restrictions. Therefore, in the present invention, the modulation signal generator 5 outputs a triangular wave so that the sign of K3 changes alternately between positive and negative. That is, in the rising portion of the triangular wave modulation signal as shown in Figure 3a, the third
As shown in FIG. b, the pitch of the output signal B of the delay device 2 increases, and conversely, the pitch decreases in the falling portion. At the turning point of the triangular wave, the rise and fall of the pitch are reversed. As a result, the pitch of the output signal B of the delay device 2 in FIG. 1 changes as shown in FIG.
This results in a trapezoidal change as shown in . The output signal B of the delay device 2 obtained as described above is electrically added to the input signal A in the adder 3, and as a result, a bead output signal is obtained at the output terminal 4.

That is, since the pitch of input signal A and the pitch of input signal B are constant in the trapezoidal peaks and valleys in FIG. 3b,
A complete bead occurs. Then, in the sloped part of the trapezoid, the bead frequency rapidly decreases and then increases again. In this way, according to the embodiment shown in FIG. 1, a perfect bead can be realized in most of one cycle of the modulation signal VM.

By the way, in conventional phase modulators, the pitch changes are not trapezoidal as shown in FIG. 3b, but are similar to a sine wave as shown in FIG. 12a, which causes a bead effect. As a result, even though phase modulation could be achieved, no bead sound effect could be obtained.

It is also known that vibrato is applied by a triangular pitch change as shown in Figure 12b, but in this case as well, there is no flat part at all, so the same effect as in Figure 12a is used. It was not possible to obtain a bead effect. Furthermore, the effects of the present invention cannot be obtained even when a clock signal generator that uses a triangular wave modulation signal and whose frequency changes in proportion to the modulation signal is used. That is, FIG. 13A shows the clock frequency F versus modulation voltage. It shows the relationship between
The solid line shows the reciprocal function, and the dotted line shows the direct proportional function. If a triangular wave modulation signal as shown in FIG. 13B is applied here, the clock frequency Fc becomes as shown in FIG. 13C. The change in pitch of the input musical tone signal is determined by the ratio of the input sampling period to the output sampling period T8(TO)°/Ts(TN
)become. In FIG. 13C, solid line F. Since its rate of change with respect to time is constant, R=T, (TO)
/T8(TN) is kept constant. On the other hand, in the broken line Fc, since Fc changes linearly, the rate of change decreases when Fc increases and increases when Fc decreases. Therefore, the ratio R decreases when FO increases and increases when Fc decreases. As a result, the pitch ratio, which is the input/output frequency ratio, has a shape close to a sawtooth wave, as shown by the broken line in FIG. 13D, and there is no range in which a constant pitch ratio can be maintained. On the other hand, according to the present invention, it becomes trapezoidal as shown by the solid line in FIG. 13D, and a sufficient flat portion can be secured. Note that the clock signal generator 6 in FIG. 1 can be constructed by a circuit as shown in FIG. 4 or FIG. 6.

FIG. 4 shows a combination of a nonlinear circuit 8 with input/output characteristics as follows and a voltage controlled oscillator 9 with linear control characteristics.

With this configuration, the clock frequency Fc changes as shown in FIG. 5 with respect to the modulation voltage VM, and a voltage controlled oscillation characteristic having the reciprocal function of equation (1) can be realized.
Note that the nonlinear circuit 8 can be configured with a polygonal line approximation circuit using an operational amplifier and a diode. FIG. 6 shows an example of a voltage controlled oscillator for obtaining a reciprocal function, where 10 is a voltage comparator, 11 is an inverter, 12 is an input terminal for modulation signal VM, 13 is an output terminal, Ra and Rb are resistors, and Q is A switching transistor, C is a charging/discharging capacitor, and I is a constant current source.

Here, the output of the voltage comparator 10 is inverted by the inverter 11 and appears as an output signal at the output terminal 13, and simultaneously controls the opening and closing of the switching transistor Q via the resistor Rb. With the modulation signal VM currently being applied to the input terminal 12, when the switching transistor Q is turned on and charges the capacitor C to +Cc, when the switching transistor Q is turned off, the terminal voltage of the capacitor C becomes As shown in Figure 7, it descends at a slope of -1t/C. When this terminal voltage drops to the positive input terminal voltage M/2 of the voltage comparator 10, the output of the voltage comparator 10 inverts and rises, and the switching transistor Q is turned on again. By repeating this operation, an output with the oscillation frequency Fc appears at the output terminal 13, and the above equations (1) and (7)
We obtain the same reciprocal function as Eq.

FIG. 8 shows a second embodiment of the invention.

In FIG. 8, the musical tone signal supplied to input terminal 1 is 2
transfer type delay device 2, 7, each delay device 2, 2'
The delayed signals B and B' are added together by an adder 3 and appear at an output terminal 4. On the other hand, the two-phase modulation signal generator 5 generates two triangular waves (modulation signals VM, VM) with mutually opposite phases.
), and each modulation signal VM, VMIIIC. Therefore, the clock frequencies Fc, fO of the clock signal generators 6, 6'
′ changes like a hyperpolicy function. In response to the output of each clock signal generator 6, 6', the driver circuit 7,
The clock pulses φ1, φ2, φ/, φ2' of γ are controlled, and the input signal A is controlled by these clock pulses φ1, φ2, φ2,
It is delayed by each delay device 2, 7 according to φ/, φ2'. At this time, input signal A and output signals B and B of delay devices 2 and 2'
The pitch ratio of ' is as shown in Figure 9.

Therefore, in the case of the embodiment shown in FIG. 8, a bead effect having twice the bead frequency can be obtained with respect to the pitch ratio as shown in FIG. 3b of the embodiment shown in FIG. According to this embodiment, the average value of the pitch frequencies of the output signals B and B' is equal to that of the input signal A, so no vibrato effect is applied.

In Fig. 8, two systems of phase modulators are provided to generate two modulated signals with mutually opposite phases, but generally, n systems of phase modulators are provided so that the phase difference is 2π/n. A similar effect can be obtained by generating a modulated signal.

The change in pitch ratio at this time is as if a trapezoidal change curve shifted in the time axis direction is added to B and B' in FIG. FIG. 10 shows a third embodiment of the present invention, in which just one set of phase modulators provides the same effect as the embodiment shown in FIG. 8, which has two sets of phase modulators. This is what I did to get it.

In FIG. 10, parts with the same symbols as in FIG. 1 have the same functions.

14 is a scale signal oscillator for an electronic instrument; 15 is a musical tone processing circuit including a key switch, a tone filter, etc.; and 16 is a triangular wave modulation signal VM as shown in FIG. 11b, as well as a trapezoidal signal oscillator as shown in FIG. A modulation signal generator 17 outputs a wave modulation signal YM, and 17 is a musical tone signal output terminal, and the output signals obtained at the output terminals 4 and 17 are added together and taken out. Note that this modulation signal YM can be produced by differentiating the triangular wave modulation signal M and converting it into a square wave, and further blunting the rising and falling portions of the square wave using an integrator with a small integration time constant. In the above configuration, the modulation signal VM is supplied to the clock signal generator 6 as in FIG.
The delay device 2 is driven by the driver circuit 7.

On the other hand, the modulation signal YM is supplied to the scale signal oscillator 14,
The oscillation frequency of the scale signal oscillator 14 is frequency-modulated in a trapezoidal manner. As a result, the pitch ratio of the output signals A and B remains the same as shown in Figure 11a, but in the section where the pitch of B is higher than that of A, the pitch of the input musical tone signal decreases by half, and conversely, the pitch of B remains the same. In the section where A is lower than A, the pitch of the input musical tone signal increases. Therefore, the pitch fluctuations of the output signals A and B are symmetrical between A and B as shown in FIG. 11d. This almost corresponds to FIG. 11a minus FIG. 11c, and is the same as FIG. 9. As described above, according to the embodiment shown in FIG. 10, the same effect as the embodiment shown in FIG. 8 can be obtained by simply providing one set of phase modulators. In any of the embodiments, if the slopes of the rise and fall of the triangular wave modulation signal are made different, the ratio of the rise and fall of the pitch can be made different.

Further, instead of electrically adding the signals by the adder 3, the input/output signals A and B may be converted into sound waves by separate speakers, and then added acoustically. Moreover, the modulation signal V
MKYM does not have to be exactly a triangular wave or a trapezoidal wave, but may be substantially a triangular wave or a trapezoidal wave, and the reciprocal function may be substantially close to the triangular wave or trapezoidal wave. As described above, the present invention supplies a musical tone signal from a musical tone signal source to a plurality of systems each having a phase modulator in at least one system, adds the outputs of each system to each other, and generates a bead sound effect. The phase modulator is configured to include clock signal generating means for changing the frequency of the output clock signal in accordance with a reciprocal function of a triangular wave, and a transfer type for delaying the musical tone signal in accordance with the clock signal. Since it is configured with a delay device, it is possible to achieve a bead effect that could not be achieved at all with conventional modulators.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG.
FIG. 3 is a diagram explaining its operation, FIG. 4 is a block diagram showing an example of the clock signal generator used in the above embodiment, FIG. 5 is a diagram explaining its operation, and FIG. A circuit diagram showing an example, FIG. 7 is a diagram explaining its operation, FIG. 8 is a block diagram showing another embodiment of the present invention, FIG. 9 is a diagram explaining its operation, and FIG. 10 is a diagram explaining the third embodiment of the present invention. A block diagram showing the embodiment, FIG. 11 is an explanatory diagram of its operation, FIG. 12 is a diagram showing pitch fluctuations in conventional modulation characteristics, and FIG. 13 is for explaining the difference in effect between the present invention and its comparative example. This is a diagram. 1...Input terminal, 2,2t...Transfer type delay device, 3...Adder, 4...Output terminal, 5... Modulation signal generator, 6, 6'...
・Clock signal generator, 7, r...Driver circuit, 8...Nonlinear circuit (broken line approximation circuit), 9.
... linear voltage controlled oscillator, 14 ... scale signal oscillator, 15 ... musical tone processing circuit, 16.
...Modulation signal generator.

Claims (1)

[Claims] 1. A musical tone signal from a musical tone signal source is supplied to each of a plurality of systems, each of which has a phase modulator in at least one system,
The output of each system is configured to generate a beat sound effect by mutually adding the outputs of each system, and the phase modulator is configured to include a clock signal generating means for changing the frequency of the output clock signal according to a reciprocal function of a triangular wave; A beat effect generating device comprising a transfer type delay device that delays the musical tone signal according to a clock signal. 2. A beat according to claim 1, characterized in that n sets of phase modulators (n is an integer of 2 or more) are provided, and the phase difference between the modulation signals of each phase modulator is set to 2π/n. Effect generator. 3 In the statement of claim 1 or 2,
The clock signal generation means is driven by a modulation signal generator that generates a triangular wave modulation signal, a reciprocal function circuit whose output clock frequency changes in proportion to the reciprocal function of this modulation signal, and an output of the reciprocal function circuit. 1. A beat effect generating device comprising a voltage controlled oscillator having linear control characteristics. 4. The beat effect generating device as set forth in claim 3, characterized in that the reciprocal function circuit is constituted by a broken line approximation circuit. 5 A musical tone signal is supplied from a musical tone signal source to two systems in which only one system has a phase modulator, and the outputs of each system are added together to create a beat sound effect, and the above-mentioned phase modulation a modulation signal generator that generates mutually synchronized triangular wave and trapezoidal wave modulation signals, a clock signal generator whose output clock signal frequency changes in accordance with an inverse function of the triangular wave modulation signal, and the clock signal generator. and a transfer type delay device that delays the musical tone signal according to the signal, and the pitch frequency of the musical tone signal is modulated by the frequency modulation by the phase modulator using a trapezoidal modulation signal outputted from the modulation signal generator. A beat effect generator that modulates in reverse phase.