JPH039480B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a wave generator for an electronic musical instrument that generates constant data corresponding to a desired musical tone frequency and generates a musical tone signal based on this constant data. [Prior Art] When obtaining a musical tone signal or a sound source signal by sequentially reading sample point amplitude values of a waveform stored in a waveform memory, a constant corresponding to the frequency of the sound to be generated is repeatedly calculated (added or subtracted), An electronic musical instrument of a type in which the read address of the waveform memory is advanced in accordance with the calculation result is already known. Conventionally, in such electronic musical instruments, constants corresponding to the above-mentioned frequencies were stored in a storage device in correspondence with each note of the keyboard (Japanese Patent Application Laid-Open No. 1983-1999).
(See Publication No. 130213). [Problems to be solved by the invention] In conventional electronic musical instruments, constants corresponding to frequencies are stored in a storage device for each note on the keyboard. If there were 61 keys, 61 types of constants would have to be stored, which would require a relatively large capacity of the storage device, resulting in high costs. The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a wave generator in which the capacity of a storage device for storing constants corresponding to frequencies is reduced. [Means for solving the problem] The wave generator for the electronic musical instrument of the present invention has the following features:
pitch designation means for designating the pitch of a musical tone to be generated; and key data generation for generating key data consisting of pitch name data and octave data indicating the pitch name and octave of the pitch designated by the pitch designation means; a storage means for storing a plurality of constant data consisting of a plurality of bits each corresponding to the frequency of a musical tone of each note name in a predetermined octave; reading means for reading out the constant data corresponding to the note name; and changing the constant data by shifting the bit position of the constant data read from the storage means according to the octave data, and changing the constant data as indicated by the key data. a changing means for outputting data corresponding to the musical tone frequency of the pitch; and a constant having a larger number of bits than the constant data that repeatedly changes at a cycle corresponding to the musical tone frequency of the pitch based on the data output from the changing means. The apparatus includes a constant data generating means for outputting data, and a musical tone generating means for generating a musical tone signal of a corresponding frequency based on the data output from the variable data generating means. [Operation] Only the constant data corresponding to each note name is stored in the storage means, the bit position of the constant data read from the storage means is shifted according to the octave data, and the bit position of the constant data read from the storage means is shifted based on the shifted constant data. Variable data that repeatedly changes at a cycle corresponding to a musical tone frequency of a desired pitch is generated, and a musical tone of a desired pitch is generated based on this variable data. [Embodiment] Hereinafter, an embodiment of the present invention will be described in detail based on the accompanying drawings. FIG. 1 is a schematic block diagram showing an example of an electronic musical instrument using the wave generator 10 of the present invention, in which a key press detection circuit 12 detects the ON or OFF operation of the key switch of each key arranged on the keyboard 11.
Outputs information identifying the pressed key. The sound generation assignment circuit 13 receives information identifying the pressed key from the pressed key detection circuit 12, and assigns the sound of the key represented by this information to one of the channels corresponding to the maximum number of simultaneous sounds (for example, 12 notes). Assign. The sound generation assignment circuit 13 has a memory location corresponding to each channel, stores a key code KC representing a certain key in the memory location corresponding to the channel to which the sound of a certain key is assigned, and stores the key code KC stored in each channel. KC is output sequentially in a time-sharing manner. In order to identify each key on the keyboard 11, as shown in Table 1, the key code KC is a 2-bit keyboard code K ₁ , K ₂ representing the keyboard type, and 3 representing the octave range.
It consists of a total of 9-bit codes: octave codes B ₁ , B ₂ , B ₃ and 4-bit note codes N ₁ , N ₂ , N ₃ , N ₄ representing the 12 note names within one octave. Ru.

【table】

[Table] In this embodiment, it is assumed that the keyboard range of the keyboard 11 ranges from _C2 note to _C7 note.
The octave code "000" in the first octave range is used only for the lowest _C2 note, and the codes _B3 to _N1 are "0001110". The octave codes B ₃ , B ₂ , B ₁ in the second octave range with the value “001” are C
The same octave chord B _{3 ,} B ₂ , B ₁ shall be used from the low-temperature C# note to the high _- pitched C note as one octave. , the octave code of the sixth octave range "101" is used for C# ₆ to _C7 notes. In this embodiment, in order to be able to produce multiple sounds at the same time, various counters, logic circuits, storage devices, etc. are dynamically configured to be used in a time-sharing manner, so that the operation of the device is regulated. The time relationship of the clock pulses used is extremely important. Figure 2a is a graph mainly showing the clock pulse φ ₁ , which controls the time division operation of each channel, and has a period of, for _example , 1 μs (microsecond; 10 ^-6 seconds). There is. Since the number of channels is 12, the 1 μs wide time slots successively separated by the main clock pulse _φ1 are the first
Channels 1 to 12 will be supported sequentially. As shown in FIG. 2b, each time slot is designated as a first channel time to a twelfth channel time in order. Each channel time occurs cyclically. Therefore, the key code KC representing the key to which the sound generation is assigned by the sound generation assignment circuit 13 is sequentially output in a time-division manner in accordance with the time of the assigned channel. For example, the first channel is assigned the C note (C ₃ ) in the second octave range of the pedal keyboard, the second channel is assigned the G note (G ₆ ) in the fifth octave range of the upper keyboard, and the third channel is assigned the C note (C 3 ) in the second octave range of the pedal keyboard. C note (C ₆ ) in the 5th octave range of the upper keyboard
is assigned, and the E note (E ₅ ) in the fourth octave range of the lower keyboard is assigned to the fourth channel.
Assuming that no sound is assigned to the 5th to 12th channels, the content of the key code KC output from the sound generation assignment circuit 13 in a time-sharing manner in synchronization with the time of each channel is as shown in Figure 2c. . All outputs from the 5th channel to the 12th channel are "0". Furthermore, the sound generation assignment circuit 13 time-divisionally outputs an attack start signal (or key-on signal) AS indicating that sound should be generated in the channel to which the pressed key is assigned the sound generation, in synchronization with the time of each channel. Furthermore, a decay start signal (or key-off signal) DS indicating that the key assigned to each channel is released and the sound should be attenuated is output in a time-divisional manner in synchronization with the time of each channel. . These signals AS,
DS is amplitude envelope control of musical tones (pronunciation control)
used for. Furthermore, the sound generation assignment circuit 13
Then, the decay end signal DF indicating that the sound generation in that channel has ended is received from the envelope generator 14, and based on the signal DF, a clear signal CC is generated that clears various memories related to the channel and completely cancels the sound generation assignment. Output. In the example shown in Figure 2c, the keys assigned to the first and second channels are currently being pressed, and the keys assigned to the third and fourth channels have been released and their sound is attenuated. , in the fourth channel, the sound generation ends at time slot _t1 , and the decay end signal DF is generated.
Assuming that the clear signal CC is output at time slot t ₂ with a delay of 12 channels, Fig. 2 d
As shown in ~g, each signal AS, DS, DF, CC is generated. In addition, when time slot t ₂ , the clear signal
Since CC is output, the attack start signal AS and decay start signal DS of the fourth channel are erased. At this time, the key code KC of the fourth channel time in FIG. 2c is erased, but is drawn as is for convenience of explanation. Various signals output from the sound generation assignment circuit 13
As shown in FIG. 2, the channels to which KC, AS, DS, and CC belong can be distinguished based on the channel time. Key code output from pronunciation assignment circuit 13
KC joins the wave generator 10, and the wave generator 10 receives variable data (address data) for sequentially reading sample point amplitude values of the musical tone (sound source) waveform from the waveform memory 15.
XqF is generated. In this embodiment, the waveform memory 15 is configured such that sound source waveforms having different numbers of feet are read out in parallel;
4 feet 4', 8 feet 8', 16 feet 1
Memories 15A to 15E are provided corresponding to the sounds of 6' and 32 feet 32', respectively. The envelope generator 14 is connected to the sound generation assignment circuit 1
Based on the various signals AS, DS, CC, etc. given from 3, an envelope waveform EV having characteristics such as attack decay is generated. Using this envelope waveform EV, a time-dependent volume amplitude envelope is added to the sound source waveform signal read out from the waveform memory 15, and the sound generation is controlled. The sound source waveform signals of each foot 2' to 32' read out from the waveform memory 15 are applied to a distribution circuit 16, and are sent to lines 17 or 18 depending on the type of keyboard, etc.
will be distributed accordingly. The sound source waveform signal distributed to the line 17 is applied to a voltage controlled filter (VCF) 19 to perform timbre control. The sound source waveform signal distributed to the line 18 is applied to a timbre filter group 20, where timbre control is performed. Voltage controlled filter 1
The filter characteristics of 9 are varied by a control voltage (not shown), and the filter characteristics of timbre filter group 20 are fixed corresponding to various tones. Therefore, sounds with different tonal qualities are produced in both series.
The timbre-controlled musical sound waveform signal passes through an appropriate sound control circuit 21 such as an expression, and is outputted from a sound system 22. A detailed example of the wave generator 10 is shown separately in FIGS. 3 and 4. A detailed example of the note decoder 23, constant memory 24, and key voltage generation circuit 25 of the wave generator 10 is shown in FIG.
8. A detailed example of the bit position switching circuit 26 is shown in FIG. In the circuits of FIGS. 3 and 4, various circuit elements are illustrated in the manner shown in FIG. Figure 5a is an inverter, Figures b and c are AND circuits,
Figures d and e in the figure show an OR circuit, and f in the figure shows a 1-bit delay flip-flop. If the number of inputs is small in an AND circuit or an OR circuit, b and d in the same figure
A normal display diagram as shown in Figure 1 is used, and if there are a large number of inputs, the diagrams shown in Figures c and e are used. In Figures c and e, one input line is drawn on the input side of the circuit, and multiple signal lines are crossed with this input line.
The intersection point between the signal line of the signal to be input to the circuit and the input line is surrounded by a circle. Therefore, in the case of c in the same figure, the logical formula is Q=A・B・D, and in the case of the example in e of the same figure, the logical formula is Q=A+B+C. Further, FIG. 5g shows a shift register, and the number of the numerator of the fraction shown in parentheses in the block indicates the number of stages of the shift register, and the number of the denominator indicates the number of bits of input data to the shift register. Although shift clock pulses are not particularly shown in the delay flip-flop and shift register, they are shifted by a main clock pulse φ ₁ (specifically, a two-phase clock pulse) having a period of 1 μs. Key code supplied from pronunciation assignment circuit 13
Of the KCs, no codes _N1 to _N4 are applied to the note decoder 23, and decoded outputs are generated on output lines corresponding to the note names represented by the note codes _N1 to _N4 . The constant memory 24 stores in advance constant data F in binary format that is proportional to the frequencies of the 12 note names C to B within one octave.
In response to the output of No. 3, constant data F corresponding to the note names represented by the note codes N ₁ to _{N 4} is read out. Constant data F read from constant memory 24
is applied to the bit position switching circuit 26, and its binary bit position is shifted to the left or right according to the value of octave switching data X given from the octave control circuit 27. In other words, the bit position switching circuit 26 performs an operation of multiplying the constant data F read from the constant memory 24 by the octave switching data X given from the octave control circuit 27. The output XF of the bit position switching circuit 26 is applied to an accumulator 28. Accumulator 28
is the constant data read from the switching circuit 26
XF is repeatedly added at regular time intervals T to obtain variable data XqF. q is a variable that sequentially increases by 1, 2, 3, 4, . . . each time the time interval T elapses. That is, in the accumulator 28, variable data XqF corresponding to the frequency of the note name in the octave range specified by the octave switching data X is obtained. Octave switching data X is octave code
Generated based on the contents of _B1 to _B3 . _{Generally , the value of data} It is now possible to change the range as appropriate. Since the frequency ratio of one octave gap is 2:1, constant memory 2
If the octave range to which the note name stored in step 4 belongs is the basic octave, then when the octave range of the note to be generated is n octaves above this basic octave, the value of X is 2 ⁿ , and when it is n octaves below. The value of X is 2 ^-n . That is, since the frequency relationship in octave units is a power of 2, the binary bit position switching circuit 26 can perform octave switching control. By the way, the value of the constant data F stored in the constant memory 24 is the frequency f of the note name in the basic octave, the number N of times the same data F is added per second in the accumulator 28, and the value stored in the waveform memory 15. It is determined by the number M of addresses for one cycle of the waveform. That is, the decimal value of the constant data F is determined by the relational expression F=f·M/N (1). Constant data F corresponding to each pitch name determined based on equation (1) is converted into a binary number, and this binary constant data F is stored in the constant memory 24 in advance. In the variable data XqF, the value of the variable q becomes N after one second, so the above equation (1) can be rewritten as follows. XF=Xf·M/N (2) Therefore, the frequency is switched in proportion to the value of the octave switching data X. As mentioned above, since the data X is given as a power of 2, the frequency Xf is changed by the power of 2 of the frequency f of the fundamental octave, and the frequency of the generated sound is changed in units of octaves. That is, the octave range of the generated sound is selected. Therefore, when the bit position switching circuit 26 shifts the bit position of the output data F of the constant memory 24 to the left (to the upper digit), the ^data
Therefore, the octave moves up by the number n of shifted bit positions. Furthermore, when the bit position of data F is shifted to the right (to the lower digit) in the same switching circuit 26, multiplication by 2 ^{- n} is performed by data X, so the octave is shifted by the number n of shifted bit positions. Go down. In FIG. 3, the note decoder 23 outputs note codes N ₁ to _{N 4} as shown in Table 1 above.
It is constituted by a group of AND circuits 23A having a logic set up so as to be able to decode each pitch name C# to C separately. The constant memory 24 stores 10-bit binary constant data F of a predetermined value in accordance with the output of the decoder 23.
( _F1 to _F10 ); and a gate section 24 that selects the output of the OR circuit group 24A according to the contents of the keyboard codes _K1 and _K2 .
It has B. Since the bit position switching circuit 26 shown in FIG. 4 is designed to perform a left shift operation (multiplication by 2 ⁿ ), the constant data F proportional to the frequency of each of the 12 tones in the lowest octave range is stored in the constant memory 24. I remember. However, the true lowest octave range shown in Table 1 above is the octave code B ₁ , B ₂ ,
The content of _B3 is "000" in the first octave range, but as mentioned above, the only note belonging to this first octave range is the _C2 note. Therefore, in the wave generator 10 of this embodiment, the second octave range in which the contents of the octave codes B ₃ , B ₂ , and B ₁ are "001" is treated as the lowest octave (basic octave), and the second octave range is Constant data F corresponding to the frequencies of the 12 pitch names (C ₂ #, D ₂ , . . . B ₂ , C ₃ ) belonging to the tone are stored in each address of the memory 24, respectively. Constant data F is also specially stored for the _C2 note, which is the only note belonging to the first octave range. In other words, as shown in Table 2, the C note (C ₃ ) belonging to the basic octave (second octave range)
Logic is set up in the OR circuit group 24A so that data with a value of 1/2 is read out as constant data F of the _C2 note. In addition, in this embodiment, data F having slightly different values for each type of keyboard is stored in the memory 2.
4, Table 2 shows only the lower keyboard tones.

【table】 〓

Claims (1)

[Claims] 1. Pitch specifying means for specifying the pitch of a musical tone to be generated, and a key consisting of pitch name data and octave data indicating the pitch name and octave of the pitch specified by the pitch specifying means. key data generation means for generating data; storage means for storing a plurality of constant data consisting of a plurality of bits each corresponding to the frequency of a musical tone of each note name in a predetermined octave; and based on the note name data from the storage means, reading means for reading the constant data corresponding to the note name indicated by the note name data; and changing the constant data by shifting the bit position of the constant data read from the storage means according to the octave data. , a changing means for outputting data corresponding to a musical tone frequency of the pitch indicated by the key data, and a changing means for outputting data corresponding to a musical tone frequency of the pitch indicated by the key data, and a changing means for changing the constant data repeatedly at a cycle corresponding to the musical tone frequency of the pitch based on the data output from the changing means. A wave generator for an electronic musical instrument, comprising variable data generating means for outputting variable data with a large number of bits, and musical tone generating means for generating a musical tone signal of a corresponding frequency based on the data output from the variable data generating means.