JPS6323558B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electronic musical instrument that generates musical tones that are closer to those of natural musical instruments, and is particularly designed to generate natural musical tones with a small amount of information. Conventionally, an easy way to generate natural instrument sounds is to generate a waveform for one period of the musical sound you are trying to generate.
One method was to store it in a ROM or the like, read out the ROM with a predetermined clock, generate a musical sound waveform, and multiply it by an envelope signal stored separately in advance. However, in reality, each natural instrument has a different envelope, and the time it takes to generate musical sounds may be long.
Storing all of this information, from the rise to the fall of a musical tone, in memory would require an enormous amount of storage capacity. In view of these points, the present invention provides an electronic musical instrument that can generate more natural musical tones with a smaller amount of information. Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of the invention. In FIG. 1, an envelope memory 1 stores envelope information corresponding to a musical tone signal to be generated. A time memory 2 stores time information representing a time interval for reading envelope information. Here, the envelope information stored in the envelope memory 1 and the time information stored in the time memory 2 are as shown in FIGS. 2 and 3.
It remembers 64 pieces of street address information. As shown in FIG. 2, addresses 44 to 63 are release portions corresponding to the falling edge of a musical tone. 3 is an address control circuit which sends an address signal to envelope memory 1 and time memory 2 based on time information given from time memory 2.
Send Ac and read envelope information and time information. When the key press signal _K0 becomes "1", the address control circuit 3 sends out an address signal Ac to read envelope information and time information from address 0 of the envelope memory 1 and time memory 2. Then, after a predetermined period of time has elapsed based on the read time information, the address signal Ac is sent out again to read out the contents of address 1 of the envelope memory 1 and the time memory 2. Similarly, the address signal is used to sequentially read out the contents of addresses 2, 3, etc.
Sends Ac. Next, when the reading of the envelope information and time information at address 43 is completed, the reading of new envelope information and time information is stopped until the key is released and the key press signal _K0 becomes "0". Next, when the key press signal _K0 becomes "0", reading from address 44 is started, and after reading address 63, reading is stopped. 4 is an interpolation circuit that performs interpolation calculations based on time information between two consecutive envelope signals generated by envelope memory 1 according to time information, and outputs an envelope signal with finer time intervals. It is. FIG. 4 shows the input and output waveforms of the interpolation circuit.
When the envelope memory 1 as shown in FIG. 4a outputs and the time memory 2 outputs time information as shown in FIG. 4b, the interpolation circuit 4 as shown in FIG. As shown in c, the envelope signal is replenished at intervals of τ. A waveform generator 5 generates a musical waveform of a musical tone signal to be generated. A multiplier 6 multiplies the envelope signal output from the envelope memory 1 by the musical tone waveform output from the waveform generator 5, and outputs the result as a musical tone signal. 7 is a digital-to-analog converter (DAC), which converts the digital musical tone signal obtained by the multiplier 6 into an analog musical tone signal. Next, the operation of the circuit shown in FIG. 1 will be explained. When the key press signal becomes "1" due to a key press, the address control circuit 3 sends an address signal Ac to the envelope memory 1 and time memory 2.
The envelope memory 1 sends out envelope information based on the address signal Ac, and inputs it to the interpolation circuit 4. The interpolation circuit 4 supplements envelope signals inputted at various time intervals based on time information so as to output envelope signals at constant time intervals. Next, multiplier 6
multiplies the output of the interpolation circuit 4 and the tone waveform output from the waveform generator 5, and outputs the result as a tone signal by the DAC 7. On the other hand, in time memory 2, the address signal
Output time information based on Ac. The address control circuit 3 receives this time information, determines when to read new envelope information and time information based on this time information, and after a predetermined period of time has elapsed, reads new envelope information and time information. . This operation is repeated in sequence to read envelope information and time information to generate an envelope signal, which is then multiplied by a musical sound waveform to generate a musical tone signal. Here, the envelope signals are read out sequentially,
Once the contents of address 43 are read out, no new envelope information is read out until the key is released, as described above. Therefore, from this point until the key is released, the multiplier 6 outputs the output of the waveform generator 5 at a constant level. When the key is then released, the envelope information from address 44 onwards in the envelope memory 1 is read out as described above, so the output of the multiplier 6 gradually attenuates. Here, when comparing the amount of information between the case where there is time information and the case where there is no time information as in the above example, using Fig. 4, Fig. 4 c corresponds to the amount of information when there is no time information. However, 20 pieces of information are required between 0≦t≦20τ. On the other hand, when time information is used, that is, in FIGS. 4a and 4b, there are seven pieces of envelope information and seven pieces of time information. Since one piece of time information usually requires fewer bits than one piece of envelope information, only 14 pieces of information are required at most, and a large amount of information can be compressed. Therefore, with this configuration, the amount of information can be significantly compressed for parts where the envelope information is constant or changes according to a certain rule, and a more natural musical sound can be produced with a smaller amount of information. can occur. FIG. 5 shows an embodiment in which the present invention is applied to an electronic musical instrument that generates musical tones using a sine wave synthesis method. In FIG. 5, parts having the same functions as those in FIG. 1 are designated by the same reference numerals, and detailed explanations will be omitted. 8-1 to 8-n are musical tone generators.
9 is a sine wave generator, which generates a sine wave signal. 10 is an adder, and each tone generator 8-1
The sum of the outputs of ~8-n is calculated and output. Here, the internal configurations of the tone generators 8-1 to 8-n are all the same except for the storage contents of the envelope memory 1 and the frequency of the sine wave signal generated by the sine wave generator 9. Further, the frequency of each sine wave is an integral multiple of the tone generator 8-1. Further, the frequency of the musical sound waveform generated by each of the musical sound generators 8-2 to 8-n is set to be an integral multiple of the frequency of the musical sound waveform generated by the musical sound generator 8-1, which should serve as a reference. . Next, the operation of the embodiment shown in FIG. 5 will be explained. The basic operation is the same as the circuit shown in FIG. The key is pressed and the key press signal K ₀ is “1”
, the address control circuit 3 outputs the address signal.
Ac to time memory 2 and each musical tone generator 8-1 to 8
- Send to n. The time memory 2 also stores time information from the address control circuit 3 and each musical tone generator 8-1 to
8-n. The musical tone generators 8-1 to 8-n generate musical waveforms based on the sent address signal Ac and time information.
Since the tone generators 8-n all perform the same operation, the musical tone generator 8-1 will be explained below. In the musical tone generator 8-1, the envelope memory 1 sends out envelope information based on the address signal Ac, and inputs it to the interpolation circuit 4. The interpolation circuit 4 supplements envelope signals inputted at various time intervals based on time information so as to output envelope signals at constant time intervals. A multiplier 6 multiplies the output of the interpolation circuit 4 and the sine wave output from the sine wave generator 5,
The musical sound generator 8-1 outputs it as a musical sound waveform.
Musical sound waveforms are similarly output from the other musical sound generators 8-n. The adder 10 is connected to each musical tone generator 8-1.
~ Add the musical sound waveforms output from 8-n,
After converting it to an analog signal with DAC7, it is output as a musical tone signal. On the other hand, the time memory 2 outputs time information based on the address signal Ac, and the address control circuit 3 receives this time information and determines when to read new envelope information and time information based on this time information. , After a predetermined period of time has elapsed, the envelope information and time information are read out anew. As mentioned above, since the frequency of the musical sound waveform outputted by each of the musical tone generators 8-1 to 8-n is set as an integer multiple of the frequency of the musical sound waveform outputted by the musical tone generator 8-1 serving as the reference, in this embodiment, an independent envelope is used. This means that sine wave synthesis is performed, and natural instrument sounds in which each harmonic changes subtly can be expressed with a smaller amount of information. In the above explanation, the address control circuit 3 is
Any device may be used as long as the interval between reading time information using the self-generated address signal Ac and generating a new address signal based on the time information changes, but as shown in FIG. An example of the address control circuit 3 is shown. To explain the address control circuit in FIG. 6, 11 is a D flip-flop (hereinafter abbreviated as DFF), which latches the value input to the D terminal at the rising edge of the signal input to the CK terminal. Output from Q terminal. Further, when the signal input to the R terminal becomes "1", the output of the Q terminal becomes "0" unconditionally. Reference numeral 12 denotes a delay circuit which delays the input signal by a sufficiently short time with respect to the key press/release interval and outputs the delayed signal. 13 is a counter;
Counts the signals input to the CK terminal. Also, the signal input to the R terminal is “1”
It will be reset unconditionally. 14 is a lock generator. 15 is a presettable counter, the truth table of which is shown in Table 1.

[Table] A comparator 16 outputs "1" when "44" immediately before the release portion in the envelope memory 1 and the output of the counter 13 match. Note that the time information here is a 4-bit signal. Next, the operation shown in FIG. 6 will be explained. key press signal
When K ₀ becomes “1”, this signal is sent to the AND circuit 17
is input to the delay circuit 12, and the inverter 18
Since it is input to the AND circuit 17 via
The output of the circuit 17 becomes "1" for the delay time of the delay circuit 12, and immediately returns to "0". this
The counter 13 and presettable counter 15 are reset by the output of the AND circuit 17, and all outputs become "0". On the other hand, since the Q output of the D.FF 11 is "0", the output of the AND circuit 19 is "0". Therefore, at the rising edge of the key press signal _K0 , D.
The Q output of FF11 becomes "1". This signal
The voltage is applied to the AND circuit 17, but as mentioned above,
When the key press signal _K0 becomes “1”, the counter 13
Since all outputs are “0”, AND circuit 2
The output of 0 also becomes "0", and the output of the AND circuit 19 remains "0". On the other hand, the presettable counter 15, which is reset at the rising edge of the key press signal _K0 , counts the clock signal generated by the clock generator 14. Here, presettable counter 15
When the outputs Q ₁ to _{Q 3} of all become “1”, the output of the counter 13 is “0”, so the comparator 1
Since the output of the NAND circuit 21 is "1", the output of the AND circuit 22 becomes "1", the counter 13 counts up, and the L terminal of the presettable counter 15 becomes "1". 1'', time information is preset at the rising edge of the clock signal. Since the presettable counter 15 continues counting from the preset value,
The time interval at which the counter 13 counts up changes depending on the time information. After repeating the above operation, when the value of the counter 13 reaches 44, the comparator 16 outputs "1", so
The output of the NAND circuit 21 becomes "0". Therefore
The output of the AND circuit 22 becomes "0" regardless of other input signals, and the counter 13 holds the value of 44 without counting up thereafter. Here, when the key press signal K ₀ becomes “0”, the NAND
Since the output of the circuit 21 becomes "1", the AND circuit 22 outputs the output of the presettable counter 15 again.
Each time Q ₀ to Q ₃ become "1", "1" is output, and the counter 13 counts up accordingly. Next, when all the outputs of the counter 13 become "1", the output of the AND circuit 20 becomes "1", so the output of the AND circuit 19 also becomes "1", the D/FF 11 is reset, and the Q terminal becomes "0". Output. Therefore, the AND circuit 22 always outputs "0" regardless of other inputs. Therefore, counter 1
3 stops counting. The above is the explanation of the address control circuit 3 shown in FIG. The interpolation circuit 4 may be of any type as long as it can obtain the output signal shown in FIG. 4c based on the input signals shown in FIGS. An example is shown below. Explaining FIG. 7 together with the timing diagram shown in FIG. 8, 18 is a counter which counts at the falling edge of the signal input to the CK terminal. Furthermore, when "1" is applied to the R terminal, the output is reset in synchronization with the clock signal applied to the CK terminal. Numerals 24 to 26 are latches, which latch the input signal at the rising edge of the signal input to the CK terminal. 27 is a subtracter which subtracts 1 from the input and outputs the result. 28 is a comparator, A
When the input and B input match, "1" is output. 2
A subtracter 9 subtracts the input of the B terminal from the input of the A terminal and outputs the result. 30 is a divider which divides the value of the A input by the value of the B input. 31 is a multiplier, 32
is an adder. In the above configuration, the counter 23 counts the clock signals, and when the A input and B input match in the comparator 28, the comparator 2
8 outputs "1" (t=t ₁ in FIG. 8). Therefore, the R terminal of the counter 23 becomes "1" and is reset at the next falling edge of the clock signal (see t in Figure 8).
= _t2 ). Also, the latch 2 is connected by the NAND circuit 33.
4 latches envelope information, and latch 26 latches time information (t=t ₂ in FIG. 8). Here we will explain why the signal obtained by NANDing the comparator output and the clock signal is used as the latch signal. If t
= t ₂ , if "1" is latched in the latch 26, the input of the comparator 28 will be "0" for the A input and "0" for the B input since the subtracter 27 subtracts 1 from the output of the latch 26. Therefore, the comparator 28 continues to output "1". Therefore, the clock signal is used to ensure that latch ₂ is activated at t=t2.
The signals of CK terminals 4 to 26 are made to rise. In the manner described above, envelope information can be newly captured at time intervals based on time information. Next, a subtracter 29, a divider 30, a multiplier 31,
The output of the adder 32 will be described. The subtracter 29 calculates and outputs {output of latch 24}-{output of latch 25}. Divider 30 divides that value by the output of latch 26, ie, the time information. Next, a multiplier 31 multiplies the output of the divider 30 by the output of the counter 23. Adder 32 outputs the output of latch 25 and in addition thereto. Therefore, the output of the adder 32 is as follows: A={output of latch 24} B={output of latch 25} n={output of counter 23} T={time information} (A-B)÷T×n+B Become. Here, each time the value of n becomes "0", the latch 24 latches new envelope information, and the latch 25 latches the output of the latch 24, that is, the envelope information from one cycle before, so that the output is as shown in FIG. 4c. An output is obtained from adder 32. 1 and 5, the output of the envelope memory 1 is supplemented between two pieces of envelope information using the interpolation circuit 4, but the output of the envelope memory 1 is directly sent to the multiplier 6. It is also possible to input the information. Further, in the above embodiments, a case has been described in which a single musical tone is generated, but it goes without saying that envelope memories, multipliers, etc. can be used in a time-sharing manner to generate multiple tones. As described above, according to the present invention, necessary envelope information can be read out at a necessary time by adding time information to envelope information. In particular, a natural musical tone requires a large amount of information because its spectral components change greatly at the rise, but in the steady state it does not change much and only requires a small amount of information. In such a case, if the present invention is used, it is possible to reduce the interval at which envelope information is read in the rising part and to increase the read interval in the stationary part, making it possible to generate envelope information extremely efficiently, thereby reducing the With the amount of information, more natural musical tones can be easily synthesized.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a diagram showing envelope information stored in the envelope memory, and FIG. 3 is a diagram showing time information stored in the time memory. Figures 4a, b, and c are diagrams showing the relationship between input and output of the interpolation circuit, Figure 5 is a circuit diagram showing the second embodiment of the present invention, and Figure 6 is an address that can be used in the present invention. FIG. 7 is a circuit diagram showing a specific example of a control circuit, FIG. 7 is a circuit diagram showing a specific example of an interpolation circuit that can be used in the present invention, and FIG. 8 is a timing diagram for explaining the operation of the interpolation circuit shown in FIG. be. 1... Envelope memory, 2... Time memory, 3... Address control circuit, 4... Interpolation circuit,
5... Waveform generator, 6... Multiplier, 8... Tone generator, 9... Sine wave generator, 10... Adder.

Claims (1)

[Scope of Claims] 1. A waveform generator that generates a musical sound waveform, an envelope storage device that stores envelope information, and a time storage device that stores time information that represents a time interval for reading out the envelope information. The reading of the time information and envelope information is started based on the key press signal generated by key press and release, and after the time based on the read time information has elapsed,
a readout control device that updates the time information and envelope information; and a readout control device that updates the time information and the envelope information; an envelope generator that generates an envelope signal by performing an interpolation operation between the envelope information before the update and the envelope information after the update according to a time interval indicated by time information; An electronic musical instrument characterized by comprising: an arithmetic unit that performs multiplication. 2. A plurality of sets of musical tone generators each including the waveform generator, the envelope storage device, and the arithmetic unit are provided, and the readout control device selects at least one of the plurality of musical tone generators based on the time information. 2. The electronic musical instrument according to claim 1, wherein envelope information used in two sets of musical tone generators is updated. 3. In the statement of claim 2, the waveform generators in the plural sets of musical tone generators are constituted by sine wave generators, and the frequency of the sine wave signals generated by these sine wave generators is set to a reference value. An electronic musical instrument characterized in that the frequency is substantially an integral multiple of the frequency of a sine wave signal generated by a sine wave generator.