JPS5857753B2 - Touch response device for electronic musical instruments - Google Patents

Description

[Detailed description of the invention] The present invention relates to a touch response device for an electronic musical instrument.

The touch response device of an electronic musical instrument is a device installed to generate expressive musical tones. It obtains a signal according to the touch (for example, the depth of a key press) and uses this signal to adjust the pitch, timbre, volume, etc. It is a device designed to control

Here, in digital electronic musical instruments, it is necessary to extract the signal corresponding to the touch as a digital signal.
The conventional method for this purpose was to obtain a voltage corresponding to the touch and pass it through an analog-to-digital converter (which internally includes a digital-to-analog converter) to obtain a digital signal. .

However, analog-to-digital converters (digital-to-analog converters) usually require a multi-stage resistance ladder circuit, so they have the drawback of high costs.

The present invention has been made in view of the above-mentioned points, and provides a touch response device for a digital electronic musical instrument that reduces costs by obtaining a digital signal in response to a touch without using a resistor ladder circuit. This is what I am trying to do.

According to this invention, a clock pulse having a predetermined duty is generated, this pulse is delayed by a time corresponding to a touch by a variable delay means, and this delayed) The pulses are logically synthesized to obtain a pulse with a duty corresponding to the touch.

Then, by measuring the pulse width of this pulse with a timer, a digital signal corresponding to the touch is obtained.

The present invention will be described in detail below based on an embodiment of the accompanying drawings.

In FIG. 1, a key switch circuit 1 is a circuit having switches corresponding to each weight of an electronic musical instrument, and generates a key code KC corresponding to a pressed key and leads it to a musical tone forming circuit 2.

The musical tone forming circuit 2 is a sound source waveform memory. Memory read control circuit, envelope signal generator, multiplier, etc. (not shown)
reads out the sound source waveform memory at a speed corresponding to the key code KC to obtain a sound source signal with a pitch corresponding to the pressed key.

This sound source output signal is multiplied by an envelope signal from an envelope signal generator, an envelope is applied, a musical tone is formed digitally, and a musical tone is formed analogously via a digital-to-analog converter, and then output.

The musical tone-formed signal then reaches the sound system 3 and is generated.

The touch detection section 4 detects the degree of key touch (in this embodiment, the depth of touch).

In the touch detection section 4, the pulse signal generation circuit 5 generates a clock pulse CPI having a predetermined frequency and duty, and guides it to the two variable delay circuits 6.

The variable delay circuit 6 receives information on the key touch depth from the key switch circuit 1, and delays and outputs the clock pulse CP1 by a time corresponding to the depth.

The duty control circuit 1 inputs the delayed clock pulse CP1' from the variable delay circuit 6 and the undelayed clock pulse CP1 from the pulse signal generation circuit 5, and logically synthesizes the two.

Therefore, the duty control circuit 7 outputs a pulse whose pulse width corresponds to the key touch depth.

The output of the duty control circuit 7 is applied to a timer circuit 8, and its pulse width is measured.

The measured value of the timer circuit 8 is inputted to the musical tone forming circuit 2, and changes the set waveform of the envelope generator, for example.

In this way, the sound system 3 generates musical tones corresponding to the depth of the key touch.

The touch detection section 4 is configured as shown in FIG. 2, for example.

In FIG. 2, the pulse signal generation circuit 5 includes one oscillator 9.
Consisted of.

The variable delay circuit 6 includes an integrating circuit made up of a combination of a fixed resistor R1 and a variable resistor R2 connected in parallel, and a capacitor C.

The variable resistor R2 is a photosensitive resistor (for example, CdS) whose resistance value changes depending on the amount of irradiated light, and light is irradiated from the lamp 10 provided in the vicinity thereof through the slit Sl.

Here, the aforementioned Slin moves in the direction of the arrow X in conjunction with the touch of a key in the key switch circuit 1, and irradiates the photosensitive resistor R2 with an amount of light corresponding to the amount of movement thereof.

Therefore, the resistance value of the photosensitive resistor R2 changes depending on the key touch depth.

In this embodiment, the deeper the key touch, the smaller the amount of light passing through the slit Sl, and the resistance value of the photosensitive resistor R2 is set to increase accordingly.

Therefore, the deeper the key touch depth is, the larger the time constant of this integrating circuit becomes.

FIG. 3 shows the change in the voltage of the capacitor C when the clock pulse CP1 is as shown in FIG. 3a.

The voltage on capacitor C is applied to inverter 11.

This inverter 11 uses its threshold voltage to delay the rise of the clock pulse CP1 in accordance with the depth of the key touch.

That is, if the voltage of capacitor C changes as shown by the solid line in Figure 3, and the threshold voltage of inverter 11 is at the level shown by the dashed line in Figure 3, the output of inverter 11 changes as shown by the solid line in Figure 3. as shown by the solid line.

Here, if the key is pressed with a deep touch, the time constant becomes thicker, so the voltage of capacitor C changes gradually as shown by the dotted line in Figure 3, and as a result, inverter 1
As shown by the dotted line in Figure 3C, the fall of the output of clock pulse CP1 is gradually delayed (that is, unless reversal is taken into consideration, the rise of clock pulse CP1 will be delayed by a time corresponding to the key touch depth). .

). The duty control circuit 7 is composed of one AND circuit 12, and receives a pulse CP1' from the variable delay circuit 6 and a clock pulse CP1' from the pulse signal generation circuit 5.
Input and take the AND of both.

Therefore, the output pulse of the duty control circuit 7 has a short pulse width τ as shown by the solid line in FIG. 3d when the key touch is shallow, and has a long pulse width τ as shown by the dotted line in the same figure when the key touch is deep. τl yells.

In this way, the duty control circuit 7 obtains a pulse having a duty corresponding to the key touch depth.

In the timer circuit 8, an oscillator 13 generates a clock pulse CP2 (third clock pulse) having a higher frequency than the oscillation frequency of the oscillator 9.
Figure e) is generated.

The AND circuit 14 makes this clock pulse CP2 conductive while the output of the duty control circuit 1 is at a bi level.

Therefore, the AND circuit 14 outputs a number of clock pulses CP2 corresponding to the depth of the key touch (the third
(see figure f).

The counter 15 receives the clock pulse C from the AND circuit 14.
P2 is counted and the count value is led to the launch circuit 16.

Here, the clock pulse CP1 is used to obtain the valley timing for the latch circuit 160 launch and the counter 15 reset.

That is, the clock pulse CP1 is input to the inverter 17 and the delay flip-flop circuit 18 of the timer circuit 8, and is input to the AND circuit 1 via the respective circuits 17 and 18.
Added to 9.

Therefore, the AND circuit 19 outputs a pulse PR as shown in FIG.

Further, this pulse PR is delayed by a delay flip-flop circuit 20 as shown in the third diagram, and then sent to a counter 15.
joins and resets its count.

As described above, a count value corresponding to the key touch depth is taken out from the latch circuit 16.

This counted value is then added to the tone forming circuit 2 to form a tone according to the depth of the key touch.

Next, another example of the configuration of the touch detection section 6 will be explained with reference to FIG. 4.

In FIG. 4, parts common to those in FIG. 2 are given the same numbers.

The circuit shown in FIG. 4 has an inverter 21 inserted on the input side of the variable delay circuit 60 shown in FIG.

Therefore, the clock pulse C from the pulse signal generation circuit 5
When P1 is a pulse as shown in FIG. 5a, the output of the inverter 21 becomes as shown in FIG. 5, and the voltage of capacitor C in the configuration of FIG. ) is just the inverse of (see 5th
(shown in Figure C).

Therefore, in this case, the output CPI' of the inverter 11 is the fifth
The output of the duty control circuit 7 is as shown in FIG. 5d, and the output of the duty control circuit 7 is as shown in FIG. 5e.

Here, if the key is pressed with a deep touch, the time constant of the variable delay circuit 60 becomes thicker, the voltage of the capacitor C changes as shown by the dotted line in FIG. The output of 1 has a delayed rise as shown by dotted lines in FIGS. 3d and 3e, respectively.

That is, contrary to the example shown in FIG. 2, the thicker the key touch depth, the narrower the pulse width of the output pulse from the duty control circuit 7, and the pulse CP2 output from the AND circuit 14.
becomes less.

Therefore, the configuration shown in FIG. 4, contrary to the example shown in FIG.
It is advantageous if the shape of the slit Sl is set so that the deeper the key touch, the thicker the amount of light passing through the slit S.

Furthermore, even if the shape of Sl is the same setting condition as in the example of FIG. 2, if the counter 15 is a down counter, the launch circuit 16 corresponds to the key touch depth as in the example of FIG. The calculated value can be obtained.

In the above embodiment, a photosensitive resistance means is used as the variable resistor R2, but the present invention is not limited to this, and the resistance value may be directly changed by a key (a so-called variable volume).
.

Further, in the above embodiment, the touch depth is detected and used as it is for musical tone control, but it is also possible to detect the touch speed based on the detected value of the touch depth.

That is, if the difference between the current output of the launch circuit 16 and the previous output of the launch circuit 16 is taken, the difference corresponds to the touch speed, and this difference is used to detect the touch speed.

As explained above, according to the present invention, it is possible to obtain a digital output in response to a key touch without requiring a resistor ladder circuit, thereby reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a detailed example of the touch detection section in FIG. 1, FIG. 3 is an explanatory diagram of the operation of the circuit in FIG. The figure is the first
FIG. 5 is a block diagram showing another detailed example of the touch detection section in the figure, and is an explanatory diagram of the operation of the circuit shown in FIG. 4. 1... Key switch, 2... Musical tone forming circuit, 3... Sound system, 4...
・Touch detection section, 5...Pulse signal generation circuit,
6...Variable delay circuit, 7...Duty control circuit, 8...Timer circuit, 9.13...
...Oscillator, 10...Rump, Sl...
...Slit, 18,20...Delay flip-flop circuit.

Claims (1)

[Scope of Claims] 1. A pulse signal generation circuit that generates a clock pulse with a predetermined duty;
A variable delay means that delays by a time corresponding to a key touch, a duty control circuit that logically synthesizes the clock pulse before the delay and the clock pulse after the delay, and a timer that controls the pulse width of the output pulse of the duty control circuit. A touch response device for an electronic musical instrument, comprising a circuit and using the above measured values for musical tone formation. 2. The variable delay means includes an integrating circuit that is repeatedly charged and discharged by the clock pulse before the delay and whose time constant changes in response to a key touch, and the set voltage is set after charging of the integrating circuit is started. Claim 1 is a circuit that obtains a delay time corresponding to a key touch by utilizing the fact that the time required to reach the key changes depending on the time constant.
A touch response device for an electronic musical instrument as described in Section 1. 3 an oscillator for the timer circuit to generate a second clock pulse having a higher frequency than the clock pulse;
2. The touch response device for an electronic musical instrument according to claim 1, wherein the touch response device is a circuit comprising a counter that counts clock pulses while the pulses are being output from the duty control circuit.