JPS6149679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electronic musical instrument that has a plurality of key switches corresponding to a plurality of keys, and can generate a single-tone frequency signal according to the position of the operated key by operating the key switch. It relates to a sound source device.

First, a conventional sound source device for this type of electronic musical instrument will be explained with reference to FIG. A constant current source circuit 1 is connected to the power supply +B, and the constant current from this constant current source circuit 1 is supplied to a resistive voltage divider in which a plurality of resistors of the same value are connected in series, and the constant current is supplied to the connection midpoint of each resistor. Key switch 3 corresponding to multiple keys, namely 3a, 3
b, 3c,... are connected, and each key switch 3
The other ends of the circuits a, 3b, 3c, . Therefore, on the input side of the sampling and holding circuit 4, a higher DC voltage is obtained as the key switch 3 closer to the constant current source circuit 1 in FIG. 1 is turned on. and,
The closer the key switches 3a, 3b, 3c, . . . are to the constant current source circuit 1, the higher the pitch of the key. The pulse generator 5 generates a pulse signal based on the output voltage obtained when the key switch corresponding to the pressed key of the key switch 3 is turned on. Since a pulse signal is generated, the pulse signal is generated at a point when a stable DC voltage is obtained, which is slightly delayed from the first point at which the pulse signal is turned on. The pulse signal from the pulse generator 5 is then supplied to the sampling and hold circuit 4, and the DC voltage from its input terminal is sampled. Therefore, in the sampling hold circuit 4, a stable current and voltage can be obtained when the key switch 3 is turned on. The output of this sampling hold circuit 4 is then supplied to an antilogarithmic function signal generation circuit 6.
This anti-logarithmic function signal generation circuit 6 is connected to the key switch 3.
This circuit converts the linear signal into an anti-logarithmic function signal according to the position of the corresponding key, and generates voltages corresponding to the frequencies of 12 pitches within one octave. The output of the anti-logarithmic function signal generating circuit 6 is then supplied to a variable oscillator (voltage controlled variable oscillator) 7, which generates a frequency signal corresponding to the above-mentioned key position. The output of this variable oscillator 7 is supplied to an amplitude modulation circuit 9 through a variable wave generator (voltage controlled variable wave generator) 8. Note that the variable wave generator 8 is controlled by the output of the pulse generator 5. Furthermore, the output of the pulse generator 5 is supplied to an envelope signal generating circuit 10 which determines the timbre, and is triggered by the pulse signal to generate an envelope signal of a predetermined waveform. and,
This envelope signal is supplied to the amplitude modulation circuit 9,
The input frequency signal is amplitude-modulated by the envelope signal, and a frequency signal having a desired frequency and an envelope corresponding to a desired tone color is generated at the output terminal 11. If this is supplied to the speaker via an amplifier etc., the key switch 3 will respond to the key operation.
In response to turning on, a single tone is generated from the speaker.

FIG. 2 shows an example of the waveform of the envelope signal generator 10 described above, in which A represents the attack time, B represents the decay time, S represents the sustain level, and R represents the release time. This waveform is selected as an appropriate waveform depending on the timbre of the frequency signal to be generated.

By the way, in the above-mentioned sound source device of an electronic musical instrument shown in FIG. 1, when a plurality of keys are pressed at the same time and a plurality of key switches 3 are turned on at the same time, priority is given to the key switch that is closer to the ground, for example. That is, in this case, regardless of which key is pressed first, priority is always given to pressing the key with the higher tone or the lower tone. However, such a situation is unreasonable in a sound source device of an electronic musical instrument, especially in a sound source device that generates a single tone. For example, if the higher-pitched key is given priority among multiple keys,
An unnatural phenomenon occurs when two keys with different pitches are pressed at the same time, and when the high-pitched key is released, the sound produced shifts from the higher pitch to the lower pitch.

In view of this, it is an object of the present invention to propose a sound source device for an electronic musical instrument in which even when a plurality of keys are pressed at the same time, the sound of the most recently pressed key is always generated preferentially. It is something.

The present invention will be described in detail below with reference to FIG. 3 by way of an embodiment thereof. In addition, in Figure 3, the first
Parts corresponding to those in the drawings will be described with the same reference numerals. Reference numeral 3 denotes a plurality of key switches corresponding to a plurality of keys, and 3a, 3b, . . . 3n correspond to keys from high to low tones, respectively. Reference numeral 12 denotes a timing signal generation circuit that generates a timing signal according to the position of an operated key by the operation of the key switch 3, and in this example, it is composed of the key switch 3, a clock oscillator 13, and a shift register 14. ing. clock oscillator 1
3 is an oscillator that generates a pulse signal of several tens of kHz, for example 20 kHz. The shift register 14 is a wired-OR shift register, and
The output of the clock oscillator 13 is supplied to the clock signal input terminal C, and the serial input terminal IN is grounded. is an inverted reset signal input terminal.
Oa, Ob,...On are parallel output terminals, and OUT is a series output terminal. And key switch 3a, 3
One ends of the key switches 3a, 3b, . . . 3n are connected to the parallel output terminals Oa, Ob, . Ru.

Then, the serial output terminal of the shift register 14
OUT is connected to the inverting reset input terminal of shift register 14.

A serial output terminal OUT of the shift register 14 is connected to an input terminal of an exponential function signal generation circuit 16. The output terminal of the exponential signal generation circuit 16 is connected to the input terminal of the sampling hold circuit 17, the output terminal of the sampling hold circuit 17 is connected to the frequency control input terminal of the variable frequency oscillator 18, and the output terminal of the variable frequency oscillator 18 is connected to the input terminal for controlling the frequency of the variable frequency oscillator 18. is connected to the input terminal of the amplitude modulation circuit 19, and an output terminal 32 is derived from the output terminal of the amplitude modulation circuit 19. Reference numeral 31 denotes an envelope signal generation circuit that generates an envelope signal to be supplied to the modulation circuit 19. This envelope signal generating circuit 31 is similar to the envelope signal generating circuit 10 in FIG. Reference numeral 20 denotes a determination circuit that determines whether one or more of the plurality of key switches 3 are activated. Reference numeral 33 denotes a detection circuit for detecting a change in the operation of the plurality of key switches 3.

The discrimination circuit 20 is an RS flip-flop circuit 21
and a JK flip-flop circuit 22. The output terminal 30 is connected to each inverting set input terminal of the flip-flop circuits 21 and 22. Further, the serial output terminal OUT of the shift register 14 is connected to the inverting reset input terminal of the flip-flop circuit 21. Furthermore, the output terminal Q of the flip-flop circuit 21 is connected to the J input terminal J of the flip-flop circuit 22. Furthermore, the serial output terminal OUT of the shift register 14 is connected to the input terminal of the flip-flop circuit 22.
Further, the positive terminal of a DC power supply 23 is connected to the K input terminal K of the flip-flop circuit 2 for constantly supplying a signal of "1" thereto. The output terminal Q of the flip-flop circuit 22 is connected to one input terminal of the AND circuit 26. This discrimination circuit 20 generates an output signal when at least one of the plurality of key switches 3 is turned on.

The detection circuit 33 is composed of an address counter 24 and a random access memory 25. The serial output terminal OUT of the shift register 14 is connected to the inverted reset input terminal of the address counter 24, and the output terminal of the oscillator 13 is connected to the clock input terminal C of the address counter 24. For example, a 6-bit binary encoded signal is supplied from the address counter 24 to the random access memory 25. This address counter 2
For the number of bits 4, n of 2 ⁿ is selected depending on the number of the plurality of key switches 3, which is close to that value. Further, the output of the oscillator 13 is supplied to the read/write control input terminal R/W of the memory 25. and memory 25
When the signal supplied to this input terminal is "1", it is in a read state, and when it is "0", it is in a write state. Also, the output terminal 30 is the memory 25
is connected to the input terminal I of. 29 has input terminal 3
The output from the output terminal 30 is supplied to the input side of the AND circuit 29 through the inverter circuit 28, and the output signal from the output terminal O of the memory 25 is supplied to the input side of the AND circuit 29. At the same time, the output of the oscillator 13 is output to the AND circuit 2.
Connected to the input side of 9. The output of the AND circuit 29 is supplied to the AND circuit 26 through an inverter circuit 27 and also to the pulse generator 15. The output of the AND circuit 26 is then supplied to the control input terminal of the envelope signal generation circuit 31. The output of the AND circuit 29 is also supplied to the pulse generator 15, which generates a sampling signal, which is supplied to the sampling hold circuit 17.

The specific circuit _of the _above -mentioned exponential function signal generation circuit 16 is as shown in FIG. The connected resistors R ₁ and R ₂ are connected, and the connection midpoint of the resistors R ₁ and R ₂ is connected to the base of the transistor Q ₁ . The emitter of transistor _Q1 is grounded, and its collector is connected to the power supply +B through resistor _R4 -resistor _R3 . The emitter of transistor Q ₂ is connected to the power supply +B, and its base is connected to the midpoint between resistors R ₃ and R ₄ . The collector of transistor Q ₂ is connected to resistor R ₅ and capacitor
It is grounded through a parallel circuit of _C1 , and an output terminal 26 is led out from its collector. In this exponential function signal generation circuit 16, when a positive pulse is supplied to the input terminal 25, the transistor Q ₁
and _Q2 are both turned on, charging the capacitor _C1 , and the voltage at its terminal instantly rises to the voltage of the power supply +B. After that, when no pulse is supplied to the input terminal 25, both transistors Q ₁ and Q ₂ are turned off, and the charge stored in the capacitor C ₁ is discharged through the resistor R ₅ , and the charge stored in the capacitor C ₁ and the resistor R ₅ is discharged. The terminal voltage of the capacitor _C1 decreases with a time constant determined by the capacitance and resistance value, respectively, and an exponential function signal is generated at the output terminal 26.

Next, the operation of this electronic musical instrument sound source device will be explained with reference to the waveform diagram of FIG. FIG. 5A shows the waveform of a 50% duty pulse signal generated from the clock oscillator 13. T ₁ ~ T ₃ , T ₁ ′ ~ T ₂ ′, T ₁ ″ ~
T ₃ ″ and T ₁ to _{T 3} indicate the rising or falling timing of this pulse signal, respectively, and the interval between adjacent points is exactly half the period of the pulse signal. When a certain key is pressed, one of the plurality of key switches 3 is turned on.In this way, from the output terminal 30, as shown in _FIG. A negative polarity rectangular wave signal rising at _T3 is obtained.In this case, if no output is yet obtained from the serial output terminal OUT of the shift register 14, the output is "1" as shown in FIG. 5C. and output terminal 30
By generating the above-mentioned negative polarity square wave signal as shown in FIG. 5B, the output of the output terminal Q of the flip-flop circuit 21 changes from "0" to "_1" at time T1 as shown in FIG. 5D. ” and this is set. Further, in the detection circuit 33, the on/off status of each switch 3 in one cycle of the shift register 14 is compared with the on/off status in the next cycle in the memory 25. Therefore, in this case, since all the key switches 3 were turned off at time _T1 , it is detected that there is a change in the operated key switches. Therefore, as shown in FIG. 5E, a rectangular wave signal is obtained on the output side of the AND circuit 29, which rises from "0" to "1" at time _T1 and falls from "1" to "0" at time _T2 . , which is supplied to the AND circuit 26 through the inverter circuit 27 and directly to the pulse generator 15.
Therefore, as shown in FIG. 5F, the AND circuit 26 provides a signal that rises from "0" to "1" at time _T2 and continues to be "1" as long as one of the key switches 3 is pressed. and at this point
At _T2 , the envelope signal generating circuit 31 is driven and continues its operating state. On the other hand, from the pulse generator 15, as shown in _FIG . This signal is output and supplied to the sampling and holding circuit 17, and the output of the exponential function signal generating circuit 16 at that point in time is sampled and held. FIG. 5H shows the exponential function signal from this exponential function signal generation circuit 16. And the point in time
At _T1 , the level of the exponential function signal shown in FIG. 5H is sampled and held to obtain a DC voltage as shown in FIG. The oscillation frequency is controlled and maintained in accordance with the frequency of the sound of the key that corresponds to the one played. The output of this variable frequency oscillator 18 is then supplied to an amplitude modulation circuit 19. The output from the envelope signal generation circuit 31 is supplied to the amplitude modulation circuit 19 to modulate the frequency signal from the variable frequency oscillator 18, and a modulated frequency signal corresponding to a predetermined tone and frequency is output to an output terminal 32. is output from.

Next, when a specific one of the plurality of key switches 3 is pressed, an output is obtained from the serial output terminal OUT of the shift register 14. That is, as shown in FIG. 5C, when a negative polarity pulse signal that falls at time T ₁ ' and rises after a predetermined period of time is output, this is supplied to the exponential function signal generation circuit 16 and the transistor Q ₁ in FIG. and Q ₂
both turn on, the capacitor _C1 is instantly charged with electric charge, and the voltage at its terminal immediately increases to the DC power supply +B.
The voltage increases to E. This state is shown in FIG. 5H. From now on, this exponential function signal generation circuit 16
Only the output waveform of the key switch 3 changes, and the waveforms of other parts shown in FIG. 5 do not change while the key switch 3 continues to be in the on state.

Next, it is assumed that one specific switch of the key switch 3 mentioned above is kept in the on state and the other switches are turned on. In this way, as shown in FIG. 5B, the output from the output terminal 30 falls at the time T1 _' ' in response to the second pressed key switch 3.
A pulse signal of negative polarity that rises at T ₃ ″ additionally appears. Then, the pulse signal obtained between time T ₁ ″ and _{T 3} ″ as shown in FIG. 5B is supplied to the output terminal I of the memory 25. As a result, it is detected that a change has occurred in the activated key switch, and as a result, the AND circuit 29 outputs a rectangular wave signal that rises at time T ₁ '' and falls at time T ₂ '', as shown in FIG. 5E. Therefore, the output of the AND circuit 26 is at the time point as shown in FIG.
It falls from " ₁ " to "0" at T ₁ '' and rises from "0" to "1" at T 2 '', thus the envelope signal generating circuit 31 is driven again at time T ₂ ''. those two key switches 3
The input signal continues to be supplied to the envelope signal generation circuit 31 while is pressed. Also, since the second key switch 3 was pressed, the pulse generator 15 generates a signal at the time point shown in FIG. 5G based on the pulse between the time points T ₁ '' and T ₂ '' as shown in FIG. 5E.
At T ₁ '', a pulse signal is obtained which rises from "0" to "1" and falls after a predetermined time, and at this point, the exponential function signal from the exponential function signal generation circuit 16 is sampled and held. In this way, this variable frequency oscillator 1 is set to a frequency corresponding to the frequency of the sound of the key corresponding to this second key switch 3.
8 frequencies are set. This frequency signal is then supplied to the amplitude modulation circuit 19 and amplitude-modulated in the same manner as described above, and a modulated frequency signal of the tone and tone corresponding to the second pressed key of the key switch 3 is outputted to the output terminal 32. .

Further, when none of the plurality of key switches 3 is turned on, a negative polarity signal is applied to the serial output terminal OUT every cycle of the shift register 14, as shown in _FIG . A pulse is output, and as a result, as shown in FIG. 5F, the output of the AND circuit 26, even if it was previously "1", immediately becomes "0", and the envelope signal generating circuit 31 is no longer driven. Also, the fifth serial output terminal OUT of this shift register 14
The generation of a pulse as shown in FIG. C resets the exponential signal generating circuit 16, and its output voltage immediately reaches E and then gradually decreases exponentially. Also, in this case, since none of the key switches 3 are pressed, no output is obtained from the sampling and hold circuit 17, and the output is "0" near time _T1 as shown in FIG. 5E.

According to the sound source device of the electronic musical instrument of the present invention described above,
Even if a plurality of keys are pressed simultaneously, the modulated frequency signal of the key corresponding to the most recently operated key switch corresponding to the plurality of keys is always obtained at the output terminal. Therefore, the unnaturalness of an electronic musical instrument as mentioned at the beginning does not occur. Furthermore, in the case of a legato performance, there is no possibility that the envelope signal generating circuit 31 will not be driven.

Furthermore, since the device has a digital circuit configuration, there is no malfunction due to chattering of the key switch 3, and the frequency of the exponential signal generator does not occur due to changes in temperature.

In the above description, a shift register in which wired OR is not possible is used as the shift register 14, but if a shift register in which wired OR is not possible is used, an OR circuit may be provided externally to each parallel output terminal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional electronic musical instrument sound source device, FIG. 2 is a characteristic curve diagram, FIG. 3 is a system diagram showing an embodiment of the present invention, and FIG. 4 is a diagram similar to that of FIG. A circuit diagram showing a part of the specific configuration, and FIG. 5 is a waveform diagram. 3 is a plurality of key switches, 12 is a timing signal generation circuit, 13 is a clock oscillator, 14 is a shift register, 16 is an exponential function signal generation circuit, 17
18 is a variable frequency oscillator; 19 is a modulation circuit; 20 is a discrimination circuit; 31
3 is an envelope signal generation circuit, and 33 is a detection circuit.

Claims (1)

[Claims] 1 A plurality of key switches corresponding to a plurality of keys, an exponential function signal generation circuit that generates an exponential function signal of a predetermined period, and a plurality of key switches corresponding to the positions of the keys operated by the operation of the key switches, and a predetermined period of the exponential function signal. A timing signal generation circuit that generates a timing signal within a cycle, a sampling hold circuit that is supplied with the exponential signal from the exponential function signal generation circuit and sampled, and an oscillation frequency that is controlled by the output of the sampling and hold circuit. a variable frequency oscillator, a modulation circuit to which the oscillation output of the variable frequency oscillator is supplied, an envelope signal generation circuit to generate an envelope signal to be supplied to the modulation circuit, and one or more of the plurality of key switches are activated. a determination circuit that determines whether or not the
a detection circuit for detecting a change in the number of activated keys among the plurality of key switches; The envelope signal generating circuit is driven to an operating state, and each time there is a change in the activated key switch, the envelope signal generating circuit is driven again, and the activated key switch is activated based on the detection output of the detection circuit. Every time there is a change, a sampling signal based on the timing signal from the timing signal generation circuit is supplied to the sampling hold circuit, and the modulation circuit generates a modulated frequency signal having a frequency corresponding to the position of the operated key. A sound source device for an electronic musical instrument, characterized in that: