KR930005218B1 - Effect circuit for electrophonic musical instruments - Google Patents

Abstract

The sound effect circuit generates chorus, phase and reverse effect using pulse coded modulation method. The circuit includes a keyboard signal generator (11) for generating keyboard signal corresponding to the depressed keyboard, an address signal generator (12) for generating address signal according to keyboard signals, a selector (13) for selecting address signal transmitted to memories, and memories (14,15) for transmitting waveform data according to address signal generated by the address signal generator to generate sound effect.

Description

Effect circuit for electronic musical instrument

1 is a block diagram of a conventional electronic instrument.

2 is a block diagram of an electronic musical instrument of the present invention.

3 is a detailed view of the effect circuit in FIG.

4 is a block diagram showing the relationship between the control signal generation circuit and the effect circuit of the present invention.

5 is a detailed block diagram of the address generator in FIG.

6 is a graph showing a relationship between a memory address and a phase of the present invention.

7 is an exemplary diagram of a phase address conversion circuit.

8 is a timing chart of the present invention.

9 is a detailed timing chart of the present invention.

* Explanation of symbols for main parts of the drawings

1: Keyboard Circuit 2: Dry Key Detection Circuit

3: tone selection circuit 4: effect circuit

5: control signal generating circuit 6: effect selection switch

7: Envelope generating circuit 8: Waveform data ROM

9 multiplier 10 sound system

11: sound reading signal generating circuit 12: address generator

13,23 selector 14,15 memory

16 Counter 17 Phase Address Conversion Circuit

18-20: Adder 21: Subtractor

22: comparator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an effect circuit for electronic musical instruments, and particularly, to be suitable for producing chorus, phase, and reverse effects in a sound source apparatus for electronic musical instruments using the PCM method.

In general, in order to produce a special sound effect in an electronic musical instrument, an expensive effect device such as a digital signal processing device or an analog filter circuit must be provided separately from the sound generating device.

FIG. 1 shows a schematic configuration of such a conventional electronic musical instrument. The keyboard circuit 1 is connected to the pressure detecting circuit 2 to supply the information about the pressed key to the sound generating circuit 5a, and this sound generating circuit In (5a), a sound signal having a corresponding tone and pitch is generated from the information on the pressed key, and the sound signal is sent to the effect circuit 4a to digitally signal the sound and to produce an effect or an analog filter. After using the circuit or the like to give an effect to the sound is sent to the sound system 10 to obtain the final output.

However, in the conventional technology as described above, most of the devices such as the effect circuit 4a perform real-time digital signal processing or complicated circuit configurations using a plurality of analog filters, thereby making it possible to use expensive devices.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional drawback, and an object of the present invention is to provide a circuit which produces a phase, chorus, and reverse effect with a simple configuration in a sound source IC using a PCM method.

When the present invention for achieving the above object described in detail by the accompanying drawings as follows.

2 is a diagram showing the configuration of an electronic musical instrument to which the present invention is applied. The key number 1 and the unique key KC information of the pressed key are sent to the effect circuit and the control signal generating circuit, and at the same time the key is pressed. A pusher detection circuit (2) for sending information indicating KON to the control signal generating signal and the envelope generating circuit, and a tone selection circuit for selecting the tone to be sounded and sending information BADD related to the tone to the control signal generating circuit and the envelope generating circuit. (3), an effect circuit (4) for generating an effect by receiving the output of the keygear detection circuit, and sending output signals WRD and WADD to the effect circuit and the waveform data rom in response to the output of the keygear detection circuit and the tone selection circuit. A control signal generation circuit 5, an effect selection switch 6 for selecting an effect and sending its output to the control signal generation circuit, and outputs of the audible detection circuit and the tone selection circuit. An envelope generating circuit (7) which receives the multiplier and sends it to the multiplier, a multiplier for multiplying the waveform data ROM (8) which sends the stored waveform data WD according to the control signal to the effect circuit and the output of the effect circuit and the envelope generating circuit; It comprises an acoustic system 10 that receives the output of this multiplier and makes a sound.

3 illustrates the effect circuit 4 of FIG. 2 according to the present invention, wherein the sound reading signal generating circuit 11 and the sound reading are generated, in which a signal KC is input from the keypress detection circuit 2 to generate a signal RPO. An address generator 12 which receives a signal and a control signal to generate an address, a selector 13 which selects an output ASW from the control signal generation circuit together with the address signal, and an output of the selector from the output and control signal generation circuit. Memory ₂ (14) to which the output RW ₂ and the output WD of the waveform data ROM are input, and memory ₁ (the output ADD ₁ from the address generator and the output RW ₁ from the control signal generation circuit and the memory _{1 to} which the output WD of the waveform data ROM are inputted ( 15).

4 shows a signal relationship between the control signal generating circuit 5, the effect circuit 4, and the waveform data ROM 8. As shown in FIG.

5 is a detailed diagram of the address generator 12 and modulo N counter 16, phase address conversion circuit 17, adder 18-20, subtractor 21, selector 23, and comparator 22. Each signal BADD, RWV, RPO, LOAD, PD, TBL, CD, PDV is applied to each of the corresponding parts, and the address signals ADD ₁ and ADD ₂ are output.

The present invention configured as described above detects the pressed keys in the keyboard circuit 1 and the pressed key detection circuit 2, and outputs the keyboard signal KC and the keyboard on / off information KON for the pressed keys, and the tone selection circuit 3 Outputs information BADD according to the tone.

Where BADD represents the first address of the tone specified as being related to the address of the waveform deatarom 8, and the information of KC, KON, and BADD is transmitted to the effect circuit 4, the control signal generating circuit 5, and the envelope. It receives from the generating circuit 7 and starts an operation.

In addition, the envelope generating circuit 7 generates envelope information EV for a desired tone when the KON signal is in the "(high level)" state, and at the same time, the control signal generating circuit 5 generates the effect selection switch ( 6) generates a control signal according to the effect and supplies it to the effect circuit 4 and the waveform data ROM 8.

The waveform data ROM 8 sends data WD for the selected sound in accordance with the control signal to the effect circuit 4 to achieve the desired effect, and then sends the resultant P to one input of the multiplier 9 to the multiplier 9 In the multiplied by the input signal P and EV is input to the sound system 10 to make a sound.

If the waveform data contained in the waveform data ROM 8 is called WD (t), the effect of the sound to be implemented is as follows.

P (t) = WD (t) + WD (t + Δt)... … … … … … … … … … … … … … … … Phase effect

P (t) = WD (TBL-t) + WD (TBL-t + Δt)... … … … … … Reverse + Phase Effect

However, P (t) = sound effect, WD (t) = natural sound, Δt = phase

P (t) = WD (t) + WD (t + X (t))... … … … … … … … … … … … Chorus + Phase Effect

TBL: Address size for one cycle of waveform

X (t) = random number.

In the above, the phase effect is an effect of mixing the phases of two identical signals with different phases, the reverse effect is an effect of reading the original sound back in time, and the chorus effect randomly changing the phase between two identical signals. In order to achieve these effects, the circuit shown in FIG. 3 is constructed.

Hereinafter, the operation timing charts of FIGS. 3 and 8 will be described.

When the key is first pressed, the KON is in the state of "1". Accordingly, the operation mode of the waveform data ROM 8 becomes R (read mode) and the operation modes of the memory ₁ (15) and the memory ₂ (14) W (write mode) is entered, and the contents of the waveform data ROM 8 are written into the memory ₁ (4) (period in which WRD = "0").

If WRD = “1” after a period of time, the memory ₁ (15) and the memory ₂ (14) enter the read mode from this time, and the desired sound effect can be started from this time.

At this time, the output of the memory _2, the address input, the selector 13 of the 14 connection according WRD is "0" during other words, ASW is "1" while the selector 15 is that the select A input memory ₁ 15 and is the address is supplied as the memory ₂ (14), and the output of ADD ₁ in the ASW is set to "0", only when the memory ₁ 15, and the memory _2, the address generator 12 to the address input (14) respectively ADD ₂ is input.

In addition, the music read signal generating circuit 11 outputs an output pulse RPO to produce a desired pitch according to the input KC information, and receives the output pulse RPO to output the ADD ₁ and ADD ₂ values from the address generator 12.

On the other hand, the phase effect has a relationship as shown in the graph of Figure 6 because the degree that the difference between ADD ₁ and ADD ₂ is related to the phase, and the following relation holds.

However, PDV is an output of the phase and address conversion circuit 17, and TBL is an address for one cycle of the waveform.

FIG. 3 is a detailed diagram of the address generator 12 of FIG. 3. The modulo N counter 16 causes the TBL value to be loaded into the counter when the LOAD signal is activated when the WRD is "0" (see timing in FIG. 9). The RPO, which is the output of the music read signal generating circuit 11, is counted and the value is output to the CD.

Therefore, the adder 18 adds the CD and the memory address BADD output from the tone color selection circuit 3 to form ADD ₁ , and the phase address conversion circuit 17 inputs phase information input from the control signal generation circuit 5. It receives the PD and length information TBL for one period of the musical sound and outputs the converted RDV.

In addition, the adder 19 modulates the output CD of the N-counter 16 and the PDV, which is a phase address value, to generate ADD _2. If the sum of the CD and the PDV is out of the TBL value, a problem arises. Processing ensures that the value of ADD ₂ does not exceed the range of one period waveform.

ADD ₁ = BADD + CD

ADD ₂ = BADD + CD + PDV; CD + PDV≤TBL

= BADD + CD + PDV-TBL: CD + PDV ＞ TBL

In order to implement this function, if the result of adding the CD and TBL values using the comparator 22 comparing the output of the adder 19 with the TBL value is larger than the TBL, the selector 23 connected to the output of the comparator 22 is input. The state becomes "1", and input A is selected. Therefore, the operation shown in the above formula is performed.

If the result of adding the CD and the TBL value is smaller than the TBL, the input of the selector 23 becomes "0" and the B input is selected and output.

The adder 20 adds BADD to the value selected by the selector 23 and outputs this value as ADD ₂ .

FIG. 6 shows the relationship between the memory address and the phase. When the address of the waveform to be sounded starts from BADD and ends at the BADD + TBL address, the memory difference is as follows. You can read the data from.

First, when REV = 1

Time A: read address of memory 1 = BADD, read address of memory 2 = BADD + PDV

Time B: Read address of memory 1 = ADD-B, Read address of memory 2 = ADD-B + PDV

Second, when REV = 0 (reverse effect)

Time A: same as for A,

Time B ': read address of memory 1 = ADD-B', read address 2 of memory = ADD-B '+ PDV

Here, the REV signal is a control signal having a reverse effect. The modulo N counter 16 of FIG. 5 performs an input count when the REV is "1", and a down count when the REV is "0" to increase the ADD ₁ . Control the feeling.

FIG. 7 shows an embodiment of the phase and address conversion circuit 17 of FIG. 5. As a conversion circuit for the phase effect, PD and TBL are the address inputs of the ROM as shown in FIG. As a conversion circuit for the chorus effect, which is stored as PDV and is a special form of the phase effect, as shown in FIG. 7B, a random number generator is used to convert between two identical signals read from the memory ₁ (15) and the memory ₂ (14). The phase can be varied.

8 and 9 illustrate the operation of FIGS. 3 and 5, when the first key is pressed, the KOK signal becomes “1”, and the WRD becomes “0” state (ASW is “1” state). ROM address is an address in ADD ₁ and ADD ₂ a 1 a periodic waveform data memory ₁ (15 going to change sequentially the waveform data ROM 8 of the WADD and memory ₁ (15) and memory ₂ (14) (8) ) And memory ₂ (14), and the length information TBL of one cycle waveform data is loaded into the N counter 16 modulo by the LOAD signal.

After the series of operations, if the REV is "1", the modulo N counter 16 counts the RPO and increases the CD value. If the REV is "0", the CD value counts the RPO. As the operation becomes smaller, the values of ADD ₁ and ADD ₂ increase and decrease accordingly.

The present invention can implement a phase, chorus, and reverse circuit in a sound source IC using a PCM method with a simple configuration, thereby eliminating the need for using an existing expensive digital signal processing circuit or an analog effect circuit, thereby reducing costs. It also has the advantage of easy ICization.

Claims (2)

A music read signal generation circuit 11 for generating a music read signal corresponding to the pressed key code, and an address generator 12 for outputting addresses associated with two memories according to the music read signal; And a selector 13 for selecting and supplying an address supplied to the memory, and two memories 14 and 15 for receiving an output from the waveform data ROM of the address from the address generator 12 and generating an effect output. Electronic circuit effect circuit characterized in that the configuration. 2. The address generator 12 is a modulo N counter 16 for counting music read signals, a phase address converting circuit 17 for converting a phase into an address, and the modulo N counter 16. An adder 18 for adding the output of the tone output circuit and the output of the tone selection circuit to output a memory address, an adder 19 for adding the output of the modulo N counter 16 and the output of the phase address conversion circuit, and the adder ( A subtractor 21 for subtracting the length of one waveform from the output of 19), a selector 23 for selecting one of the outputs of the adder 19 and the subtractor 21, and a length for one waveform And a comparator 22 which compares the output of the adder 19 and sends its output to the selection input of the selector 23, and an adder 20 which adds the output of the selector 23 and the output of the tone selection circuit. Electronic circuit effect circuit, characterized in that configured to include .

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