JP3459093B2 - Music synthesizer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a musical tone synthesizer for forming a musical tone waveform. 2. Description of the Related Art Conventionally, there has been known a musical sound synthesizer for generating an expressive musical sound by inputting an excitation waveform to a closed loop circuit composed of a delay circuit, a filter, an amplifier and the like. (See JP-A-1-303681). FIG. 7 is a block diagram showing an example of the configuration of this type of musical sound synthesizer. In FIG. 1, reference numeral 1 denotes an excitation waveform generating circuit, which generates an original waveform on which a musical tone waveform is based. Reference numeral 2 denotes an input envelope generating circuit which generates and outputs an envelope waveform.
3 is a multiplication circuit, and 4 is an addition circuit. 5 is a delay circuit, 6
Is a filter, and 7 is an amplifier (multiplier) that amplifies (or attenuates) with the amplification factor α, and the above-described circuits 4 to 7 constitute a closed loop circuit 8. In such a configuration, the excitation signal generated by the excitation waveform generation circuit 1 is multiplied by the envelope signal generated by the input envelope generation circuit 2 in the multiplication circuit 3, and the multiplication result is supplied to the addition circuit 4. You. The addition circuit 4 adds the multiplied signal and the output of the amplifier 7 and outputs the addition result to the outside of the closed loop circuit 8 as a sound source signal. The addition result is fed back to the addition circuit 4 after passing through the delay circuit 5, the filter 6, and the amplifier 7. The excitation signal output from the excitation waveform generation circuit 1 is deformed by circulating through the closed loop circuit 8, becomes a desired sound source signal, and is output from the addition circuit 4. The excitation waveform generating circuit 1 and the input envelope generating circuit 2 start generating respective signals in accordance with, for example, a key-press signal of a keyboard (not shown). Also,
The period of the excitation signal generated by the excitation waveform generation circuit 1 and the delay time of the delay circuit 5 are set based on the pitch of a musical tone to be generated. In the above-described conventional tone synthesizer, when the excitation signal has a continuous waveform (a plurality of cycles), the rising edge of the envelope of the output signal is reduced. The phenomenon occurs. FIG. 8 is a waveform diagram showing an example of the input / output signal waveform in this case. In this figure, (a) is an excitation waveform, (b) is an input envelope,
(C) shows the output signal waveform, and the dashed line in (c) shows the envelope of the output signal. Rise of the envelope of the output signal as shown in this figure, the characteristics of the closed loop circuit 8, resulting in dull rounded. For this reason, there has been a problem that the formation of a musical tone is hindered, for example, a sense of attack at the time of sound generation is lost. The present invention has been made under such a background, and corrects the rounding of the envelope of an output signal.
It is an object of the present invention to provide a tone synthesizer capable of generating an output signal having a desired envelope. According to the present invention, at least a first delay means is provided.
An input signal is applied to loop means in which a first filter and a first filter are connected in a closed loop, and the input signal circulates in the loop means to form a tone signal. Means, at least a second delay means and a second filter
And forming an inverse filter for the closed loop,
By inputting the envelope signal to the inverse filter, an envelope signal correction means for correcting the envelope signal is provided so that the level of the input signal becomes high for a predetermined time at the rise of the input signal, and thereafter becomes low. After applying an envelope based on the corrected envelope signal, the envelope is applied to the loop means. Further , the invention related to the present invention provides a tone synthesis wherein a tone signal is formed by applying an input signal to at least a loop means having a delay means connected in a closed loop and circulating the input signal in the loop means. In the device, according to the setting state of the characteristics of the loop means, at the rising of the input signal is high level for a predetermined time,
Thereafter, an envelope generating means for generating an envelope signal having a low level is provided, and the input signal is provided with an envelope based on the envelope signal and then added to the loop means. In the structure of this related invention
According to the setting state of the characteristics of the loop means,
Loop signal to simplify the configuration.
Wear. According to the above arrangement, the second delay means is used to perform the
Inverse filter for loop means having one delay means
And use this inverse filter to supplement the envelope signal.
Since the correction is made, the input signal is input to the loop means after its rising portion is increased , so that the rounding of the envelope generated in the loop means can be corrected. An embodiment of the present invention will be described below with reference to the drawings . [0011] Figure 1 is a block diagram showing a configuration of a musical tone synthesizing apparatus according to actual施例of the present invention, in this figure, same reference numbers are assigned to corresponding parts in FIG. 7, a description thereof will be omitted . The embodiment shown in this figure differs from the circuit of FIG. 7 in that an envelope correction unit 15 (FIG. 1) is provided between the input envelope generating circuit 2 and the multiplying circuit 3 in FIG. In the envelope correction section 15, 1
0 is a delay circuit, and 11 is a filter, which has the same characteristics as the delay circuit 5 and the filter 6 in the closed loop circuit 8, respectively. Reference numeral 12 denotes an amplifier (multiplier) having an amplification factor of -α. Reference numeral 13 denotes an addition circuit, and reference numeral 14 denotes a limiter. The limiter 14 outputs the input as it is when the input takes a positive value, and outputs “0” when the input takes a negative value.
Is output. FIG. 2 shows signal waveforms at various parts of the envelope correction section 15. In FIG. 2, (a) shows an input envelope signal generated from the input envelope generating circuit 2,
(B) is an output signal of the amplifier 12, and (c) is a limiter 14.
3 shows respective waveforms of the output signal. The envelope correction section 15 performs a function of correcting in advance the deformation of the input envelope signal received by the closed loop circuit 8.
The reverse operation is performed on the input envelope signal. That is, the filter 11 and the amplifier 12 are
Is an inverse filter of. As a result, the envelope of the output signal of the closed loop circuit 8 can be eliminated, and an envelope having a substantially constant amplitude can be obtained. Next, a modification of the above embodiment will be described. Since the waveform of the correction signal output from the envelope correction unit 15 in the above-described embodiment (see FIG. 1) always has a similar shape, in this embodiment, the correction signal is directly generated in the envelope generation circuit 16. FIG. 3 is a block diagram showing the configuration of a musical sound synthesizer according to this modification . In this figure, the same reference numerals are given to parts corresponding to the respective parts in FIG. 7, and the description thereof will be omitted. The embodiment shown in this figure differs from that of FIG. 7 in the configuration of the envelope generating circuit 16. The envelope generation circuit 16 forms and outputs an envelope signal shown in FIG. This envelope signal has a rising magnitude of “1” and holds “1” for a time DT. Here, the time DT is a delay time with respect to the fundamental frequency of the closed loop circuit 8 (hereinafter, referred to as one delay loop cycle). Next, the envelope signal has a magnitude of “1-α1”, which lasts for a certain period of time, and then becomes “0”. Here, α1 is a gain (gain for the fundamental frequency) determined by both the filter 6 and the amplifier 7. By applying the envelope signal to the excitation signal, it is possible to perform substantially the same correction as in the above-described embodiment . Next, an embodiment related to the present invention (hereinafter referred to as a related embodiment)
This is referred to as a continuous example. ) Will be described. FIG. 5 is a block diagram showing a configuration of a musical sound synthesizer according to the related embodiment. In this figure, the same reference numerals are given to parts corresponding to the respective parts in FIG. 7, and the description thereof will be omitted. This related embodiment is shown in FIG.
The difference from the first embodiment is that a correction unit 24 is added. Further, similarly to the previous embodiment, the delay time of the delay circuit 5 is set based on the pitch of the musical sound to be generated. In the correction unit 24 (FIG. 5), reference numeral 19 denotes a timer. The output of the timer 19 is normally "1" and becomes "0" only during the gate time GT from the start of sound generation. 20 is an inverter, and 21 is a gate circuit. The gate circuit 21 is opened during the gate time GT, and the excitation signal output from the excitation waveform generation circuit 1 is supplied to the amplifier 22.
Is output to the adder circuit 23 through. The addition circuit 23 adds the output of the multiplication circuit 3 and the output of the amplifier 22 and outputs the result to the closed loop circuit 8. Here, the gate time GT is 1
This time is equal to the delay loop period DT. [0021] Figure 6 shows the signal waveforms in the related examples, in Fig. (A) is input envelope signal, (b) shows the respective waveforms of the output signal of the inverter 20. The excitation signal to which the envelope has been applied has its rising edge emphasized only for one delay loop period, and is thereafter supplied to the closed loop circuit 8. This makes it possible to correct the waveform rounding based on the closed loop circuit 8. The amplification factor β of the amplifier 22 can be changed, and can be set to a value at which the user of the device thinks that the sense of attack is improved in terms of hearing. The gate time may be set by the user as a ratio to one delay loop cycle. For example, when this ratio is “1”, the gate time GT is equal to one delay loop period, and when this ratio is “2”, the gate time GT is
Is twice as long as one delay loop period, and when this ratio is "0.5", the gate time GT is half the time of one delay loop period (the delay loop period corresponds to the pitch). The gate time G according to the pitch
T will be controlled). In the configuration of FIG. 5, the gate circuit 2
One input I may be connected to the output of the multiplying circuit 3 and the correction may be performed by the excitation signal after the envelope is applied. Further, the above-described embodiment, modified example, and related
In the embodiment, the excitation signal is corrected at the input of the closed loop circuit 8, but the correction may be performed at the output of the closed loop circuit 8. In this case, the response waveform when the input envelope signal is input to the closed loop circuit 8 is examined, a correction signal is created from its reciprocal, and the correction signal is multiplied by the output signal of the closed loop circuit 8 to perform the correction. It is also possible to provide an amplifier for controlling the gain in accordance with the level of the signal, a so-called compressor or the like, connect the output of the closed loop circuit 8 to this compressor, and keep the amplitude width of the output signal constant. Further, the tone synthesizer shown in the embodiment can be implemented by a hardware circuit.
It can also be configured by executing a microprogram using an SP or the like. As described above, according to the present invention, the input signal is input to the loop means after its rising portion is increased, so that the envelope of the signal generated in the loop means is obtained. Bluntness is corrected, and a favorable effect on the subsequent formation of musical tones is obtained. In the present invention, the first
Since the envelope signal is generated by using the second delay means in the same manner as the loop means having the delay means, the effect of the first delay means can be simulated by the second delay means .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a musical tone synthesizing apparatus according to the embodiment the present invention. FIG. 2 is a diagram showing signal waveforms at various parts in FIG. 1;
(A) is the output signal of the input envelope generating circuit, (b)
Indicates the output signal of the amplifier 12, and (c) indicates the output signal of the limiter 14. FIG. 3 is a block diagram showing a configuration of a musical sound synthesizer according to a modification of the present invention. FIG. 4 is a waveform chart showing an output signal of the envelope generation circuit of FIG. 3; FIG. 5 is a block diagram showing a configuration of a musical sound synthesizer according to an embodiment relating to the present invention. FIG. 6 is a waveform diagram showing signals of respective parts in FIG. 5,
(A) is the output signal of the input envelope generating circuit, (b)
Indicates an output signal of the inverter 20. FIG. 7 is a block diagram showing a configuration of a conventional tone synthesis device. FIG. 8 is a waveform diagram illustrating a signal of each unit in FIG. 7,
(A) shows an output signal of the excitation waveform generation circuit, (b) shows an output signal of the input envelope generation circuit, and (c) shows an output signal of the closed loop circuit 8. [Description of Signs] 1 Excitation waveform generation circuit 2 Input envelope generation circuit 7 Amplifier 8 Closed loop circuits 15, 24 Correction unit 21 Gate circuit

Claims (1)

(57) [Claims 1] At least a first delay means and a first filter
An input signal is applied to a loop means having a closed loop connection with a filter, and the input signal circulates through the loop means to form a tone signal. In the tone synthesizer, an envelope signal generating means for generating an envelope signal; At least a second delay means and a second filter,
Forming an inverse filter for the closed loop, and inputting the envelope signal to the inverse filter, the envelope signal for correcting the envelope signal so as to be at a high level at a rise of the input signal for a predetermined time and then to a low level thereafter A musical sound synthesizer comprising a correction means, wherein the input signal is provided with an envelope based on the corrected envelope signal and then applied to the loop means.