JPS59837B2 - Electronic musical instrument key touch data generation circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a key touch data generation circuit for an electronic musical instrument.
In particular, aftertouch control (which controls musical tones in response to changes in pressing force when a key is continuously pressed)
This invention relates to a key touch data generation circuit for touch response control (also known as second touch control).

In digital electronic musical instruments, musical tone signals are formed digitally, so analog voltages obtained from key touch sensors for aftertouch control are converted into digital signals and then used for musical tone control.

Conventionally, an analog-to-digital conversion circuit was used to directly convert the analog voltage output from a key touch sensor into a digital signal, so a high-speed analog-to-digital conversion element that matches the processing timing of a digital system has become necessary. It was necessary. For example, the maximum number of simultaneous polyphony is 1.
When there are 6 sounds and these are generated in a time-division manner, the time slot width assigned to each sound is usually about 1 μs, and in this case, in order to obtain one word of digital touch data, the time slot width allocated to each sound is about 1 μs. Must be converted from analog to digital. Generally, analog-to-digital conversion is (
Since it takes time (compared to digital-to-analog conversion), if high-speed operation is required, a greater burden is placed on the conversion element. In addition, in the method of directly converting an analog sensor output into a digital signal, if noise were to occur in the sensor output, digital conversion would be performed in response to the noise, making it easy to cause malfunctions. This invention was made to eliminate the above-mentioned drawbacks, and instead of directly converting the analog voltage from the touch sensor into digital data, when obtaining digital touch data at a certain sample time, Convert the digital touch data obtained from the touch sensor into digital to analog, compare the magnitude of this analog voltage with the analog voltage from the touch sensor, and if the difference between the two voltages is within a certain range, the digital value will be the same as the value one sample before. The touch data is held, and if the analog voltage of the sensor exceeds the certain range and is large (or small), a certain value is added or subtracted from the digital touch data one sample before to obtain new digital touch data. The present invention aims to provide a key touch data generation circuit as described above.

Hereinafter, the present invention will be explained in detail based on the embodiments shown in the accompanying drawings.

FIG. 1 schematically shows a key touch data generation circuit 11 according to the present invention applied to a multitone electronic musical instrument 10, in which a key touch sensor 13 for aftertouch control is individually arranged corresponding to each key on a keyboard 12. provided.

The key touch sensor 13 outputs an analog voltage in response to changes in pressing force when the key is continuously pressed, and is a known aftertouch control using conductive rubber, a strain gauge, or other appropriate detection element. sensors can be used. Each key touch sensor 13
The output is supplied to an analog multiplexer 14, time-division multiplexed by the multiplexer 14, and applied to the key touch data generation circuit 11. The sound generation assignment circuit 15 is a known circuit for allocating a key being pressed on the keyboard 12 to one of a specific number (for example, 16) of sound generation channels.

Each of the 16 pronunciation channels is created in a time-division manner.
For example, the time slot width of one channel is 1 μs.

The sound generation assignment circuit 15 outputs a key code KC representing a key assigned to each channel in a time-division manner in accordance with the time slot of that channel. This key code KC is applied to a tone generator section 16, and the tone generator section 16 generates a musical tone signal corresponding to the key represented by the key code KC for each channel. The key code KC output from the sound allocating circuit 15 in a time-divisional manner is added to the human control power of the analog multiplexer 14. The multiplexer 14 samples the analog voltage from the key touch sensor 13 corresponding to the key represented by the key code KC, leads it to an output line 17, and supplies it to the key touch data generation circuit 11. As shown in the figure, this analog multiplexer 14 has analog gates 14a to 14n corresponding to the key touch sensor 13 of each key, and a decoder 14D decodes the key code KC supplied in the time slot of each channel. The analog gates 14a to 14n are opened and closed depending on the output. Therefore,
In a time slot of a certain channel, only the analog voltage from one key touch sensor 13 corresponding to the key assigned to that channel is supplied to the key touch data generation circuit 11 via the multiplexer 14. The key touch data generation circuit 11 generates digital touch data TD for aftertouch control based on the analog voltage applied from the key touch sensor 13, and applies this to the tone generator section 16.

Based on this touch data TD, the tone generator section 16 controls musical tone elements such as the volume or timbre of the musical tone generated in the corresponding channel. Note that the following description will be made assuming that the volume is controlled. The output musical tone signal of the tone generator section 16 is given to a sound system 18 and generated. Next, details of the key touch data generation circuit 11 will be explained with reference to FIG.

The key touch data generation circuit 11 includes a counting section 19 that can be used for three functions: up counting, down counting, and count value hold.

The count content of this counting unit 19 is the digital touch data T.
D is supplied to the tone generator section 16.
The counting unit 19 adds a constant up rate value URV to the current count when an up command UP is given, and adds a constant down rate value DR when a down command DOWN is given.
V is subtracted from the current count contents, and the current count contents are held when a hold command HOLD is given. Key touch sensor 1
The sensor output voltage A supplied from 3 through multiplexer 14 and line 17 is applied to one of the analog comparators 20 (e).

The output voltage B of the digital-to-analog converter 21 is applied to the other input (c) of the comparator 20. The counting output (digital touch data TD) of the counting section 19 is input to the input of the digital-to-analog converter 21.
22]. Therefore, the digital data corresponding to the count output of the counting section 19 (that is, the digital touch data TD at the current sample time) is converted into an analog voltage B by the digital-to-analog converter 21. In the comparator 20,
This "analog voltage B obtained by converting the digital touch data TD at the current sampling point into analog by including a dead zone Δ" is compared with the touch sensor output voltage A.
The comparison output of this comparator 20 is connected to latch circuits 23 and 2.
4 to latch corresponding to the sample time. Depending on the latched comparison result, the counting control logic 25 generates the up command UP, down command DOWN, or hold command HOLD to control the counting of the counting section 19.
Key touch data generation circuit 1 configured approximately as described above
1, the counting of the counting section 19 is controlled in the following manner to generate digital touch data TD.

As shown in Fig. 3, a dead band △ is added to the digital touch data TD at the current sampling point, and if the touch sensor output voltage A falls within this dead band △, the count value of the counter 19 is held, and if it is higher than the dead band △. The counter 19 is caused to count up (or down) by a constant value regardless of the degree of the difference, and if it is lower than the dead zone Δ, it is caused to count down (or up) by a constant value regardless of the degree of the difference. As a result of this counting control, digital touch data TD at a new (next) sample time point is obtained. Further details will be explained.

The counting unit 19 performs a counting operation in a time-division manner corresponding to the time-division time slot of each channel in the voltage instrument 10 (FIG.
6) and a 16-stage shift register 27 corresponding to 6).

The shift register 27 is shift-controlled by a clock pulse φ having a period of 1 μs, which is the same as that which controls the time division time slot of the electronic musical instrument 10. The final stage output of the shift register 27 is output as digital touch data TD and is also returned to the adder 26. The other input of the adder 26 is connected to a gate 29 or 3 via an OR circuit group 28.
Uprate value URV or downrate value D from 0
RV is supplied. When the up command UP is given, the gate 29 opens and adds the up rate value URV to the adder 26. Gate 3 when down command DOWN is given
0 opens and adds the down rate value DRV to the adder 26.
For example, the down rate value DRV is expressed as a two's complement number, and when this down rate value DRV is applied to the adder 26, a subtraction is effectively performed. Hold command H
When OLD is applied, gates 29 and 30 are inhibited and the output of the final stage of shift register 27 passes through adder 26, holding the previous count result. The digital touch data TD output from the counting section 19 corresponds to a negative decibel amount, and when all bits of the data TD are 'O', that is, the maximum value, it corresponds to 0 [DB], which is Specify the maximum volume.

When all bits of data TD are "1", this corresponds to -XCdB] (for example, -96dB) which indicates the minimum volume. Therefore, the larger the value of the data TD, the lower the volume, and the smaller the value, the higher the volume. From this, it is clear that the initial values of the counting section 19 must be all 1, but the initial value setting circuit (reset circuit)
The illustration of is omitted. For example, when a key assigned to a certain channel is released, the contents of the shift register 27 corresponding to that channel may be reset to all 11's. The digital touch data TD output from the counting section 19 is sent to a decibel-linear conversion circuit 31 in the circuit 22 and a read-only memory (ROM) 3.
2.

The decibel-linear conversion circuit 31 is a circuit that converts touch data TD expressed in negative decibel amounts into linear amounts. Therefore, the data Q1 obtained from this decibel-linear conversion circuit 31 linearly corresponds to the volume level controlled by the touch data TD. In other words, Q
If the value of 1 is large, the volume is high, and if the value is small, the volume is low. The read-only memory 32 is a touch data TD.
The dead zone setting value △Q is read out according to the value of .The larger the value of the touch data TD input as the address signal, the smaller the △Q is read out, and the smaller TD is, the larger the △Q is read out. It's getting old.

This narrows the dead band Δ when the volume controlled by the touch data TD at the current sample point is small (the value of TD is large), making it possible to respond to small fluctuations in key touches; This is because when the volume controlled by the touch data TD is large (the value of TD is small), the dead zone Δ is widened so that it does not respond to fluctuations in key touches that are not very large. The dead zone setting value ΔQ is added to the adder 33 and is the value Q of the touch data TD expressed as a linear amount given from the decibel-linear conversion circuit 31.
It is added to 1.

From the adder 33, a value Q2 (-Q1+ΔQ) is obtained by adding the dead zone setting value ΔQ to the linear value Q1 of the touch data TD.
is obtained. The values Q1 and Q2 are applied to a time division circuit 34, selected in a time division manner between the first half cycle and the second half cycle of the clock pulse φ, and then supplied to the digital-to-analog converter 21.

As mentioned above, the period of 1 μs of the clock pulse φ corresponds to the time division time slot for one channel, and during one period of the clock pulse φ, the values Q1 and Q2 regarding one channel are input to the time division circuit 34. There is. Therefore, the value Q1 is selected in the first half period of the clock pulse φ,
The value Q2 is selected in the second half of the cycle. Assuming that the clock pulse φ is a pulse with a duty of 50%, and the level of the first half cycle is ``0'' and the level of the second half period is ``1'',
The value Q1 is selected at the 6r' timing of the pulse φ, which is the inversion of the clock pulse φ, and the value Q2 is selected at the 1'' timing of the clock pulse φ. The value Q1 is converted into an analog voltage at
1) is output, and in the latter half of the cycle, the value Q2 converted into an analog voltage (this is referred to as B2) is output.

These B1 and B2 are applied to the comparator 20 as input voltage B. Since the touch sensor output voltage A of the same key is applied to the other input of the comparator 20 during one period of the clock pulse φ (during the time slot of one channel),
This voltage A and the voltages B1 and B2 are sequentially compared.
The comparator 20 outputs ``1'' of [A>B'', and ``
Outputs "0" for "A<B".

The latch circuit 23 reads the comparison output of the comparator 20 when the clock pulse φ is "1", and the latch circuit 24 reads the comparison output of the comparator 20 when the clock pulse φ is 11 degrees. That is, the comparison result between A and B1 in the first half cycle of the clock pulse φ is latched in the latch circuit 23, and the comparison result between A and B2 in the second half cycle is latched in the latch circuit 24. The counting control logic 25 consists of a NOR circuit 35, an exclusive OR circuit 36, and an AND circuit 37, each of which receives the latch outputs of the latch circuits 23 and 24.

The NOR circuit 35 outputs an up command UP, the exclusive OR circuit 36 outputs a hold command HOLD, and the AND circuit 37
outputs a down command DOWN. Therefore, the relationship between the comparison results in the comparator 20 and each counting command is as shown in the table below. In this example, it is assumed that the touch sensor output voltage A becomes high when the key is pressed strongly (that is, when the volume is increased) and becomes low when the key pressing force becomes weak. In other words, when A>B1 and A>B2 are satisfied, the sensor output voltage A is higher than the voltage corresponding to the value obtained by adding the dead zone △ to the digital touch data TD at the current sample time, so it is necessary to increase the volume. There is.

Therefore, a down command DOWN is generated from the AND circuit 37, a predetermined down rate value DRV is subtracted from the touch data TD at the current sample time, and the value of the touch data TD at the next sample time is reduced to obtain a negative tesibel amount. Make it quieter (i.e. make it louder). Also, A<B1 and A<B2
When this is satisfied, the sensor output voltage A is lower than the voltage corresponding to the touch data TD at the current sample point, so the volume needs to be reduced. Therefore, an up command UP is generated from the NOR circuit 35, a predetermined up rate value URV is added to the touch data TD at the current sampling point, and the value of the touch data TD at the next sampling point is increased to produce a negative decibel amount. Make it louder (i.e. lower the volume). Furthermore, when A>B1 and A<B2 are satisfied, the sensor output voltage A is within the range of the dead band △ corresponding to the touch data TD at the current sample time, so The same value is maintained at the next sample time so that the volume does not change. Therefore, a hold command HOLD is generated from the exclusive OR circuit 36, so that the touch data TD of the current sample point is held in the counting section 19 at the next sample point as well. Furthermore, A
Theoretically, it is impossible for both <B1 and A>B2 to be satisfied, but in the unlikely event that such a situation occurs due to malfunction due to noise etc., the exclusive OR circuit 36 will operate and hold the counting section 19. state. Next, a modification example will be explained.

The up-rate value UR and the down-rate value DR do not need to be the same value, and may each be set to appropriate values.

In general, after-touch control improves responsiveness when applying weight (when applying pressure to a key), and improves responsiveness when applying weight (when applying pressure to a key).
It is known that if the responsiveness (when the key press force is relaxed) is decreased, it will be easier to play. Therefore, it is preferable to set URV<DRV so that the rate of change of touch data TD in the direction of volume increase is faster than the rate of change of touch data TD in the direction of volume decrease. In Figures 1 and 2, compound tone processing was used as an example, but
In the case of single note processing, the shift register 27 of the counting section 19 is set to 1.
If it is a stage\・oAlso, in the above embodiment, the digital touch data TD output from the counting section 19 is displayed in negative decibels, but this is not an essential requirement, and a linear display proportional to the volume. It may be.

In that case, the manner in which the up command UP and down command DOWN are generated is opposite to that of the above embodiment. In the above example, the value Q1
and Q2 are time-divisionally processed to perform digital-to-analog conversion and analog comparison; however, the present invention is not limited to this.
It is also possible to provide two series in parallel, and compare the voltages A and B1 and A and B2 simultaneously within one sample time.

In the above embodiment, the dead zone Δ is provided only above the touch data TD at the current sample time, but it may be provided only below the TD, or above and below the TD.

In addition, after analog conversion of the dead band setting value △Q, B1
It is also possible to obtain B2 by adding it to B2. As explained above, according to the present invention, only one addition or subtraction is performed when obtaining digital touch data TD at one sample point, so high-speed operation like conventional analog-to-digital conversion elements is not required. First, the burden on the circuit components is reduced.

Furthermore, even if the input touch sensor output voltage changes rapidly, the digital touch data TD will only increase or decrease to a value that corresponds to a fixed up-rate value URV or down-rate value DRV. digital touch data TD can be obtained. Moreover, even if noise is added to the touch sensor output voltage, the digital touch data TD does not respond to sudden changes in human power for the reason described above, so no harsh noise will appear in the digital touch data TD. Further, since the dead zone Δ is set so as not to respond to slight fluctuations in key touch, digital touch data TD suitable for aftertouch control can be obtained.

In other words, the player does not respond to unconscious changes in the touch of a key during a performance, but rather responds to conscious changes in the touch of a key. In addition, since the dead zone Δ is made to change according to the magnitude of the immediately preceding touch data TD, the presence of the dead zone is felt evenly in terms of performance, making it extremely easy to play. That is, when the volume currently controlled by the touch data TD is low, the dead zone becomes narrow, and when the volume is high, the dead zone becomes wide, and the performer feels that the dead zone does not change.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing an example of an electronic musical instrument to which a key touch data generation circuit according to the present invention is applied, and FIG. 2 is a block diagram showing an embodiment of the key touch data generation circuit according to the present invention. FIG. 3 is an explanatory diagram schematically showing the counting control mode in the above embodiment. 10...Electronic musical instrument, 11...Key touch data generation circuit, 19...Counting section, 20...
... Analog comparator, 22 ... Circuit for setting dead zone, 25 ... Counting control logic.

Claims (1)

[Scope of Claims] 1. In a key touch data generation circuit of an electronic musical instrument that generates digital touch data based on an analog sensor output voltage obtained from a key touch sensor provided corresponding to a key, the counting output is a counting means for outputting as touch data; a dead zone setting means for setting a dead zone above or below the value of the touch data; a digital-to-analog conversion means for generating an analog voltage corresponding to the touch data and the dead zone; a comparison means for comparing the analog voltage from the means and the sensor output voltage; and based on the comparison result by the comparison means, if the sensor output voltage is within the dead zone, the count content of the counting means is retained. and counting control means for adding or subtracting a constant value to the count of the counting means when the sensor output voltage is out of the dead zone. 2. The key touch data generation circuit according to claim 1, wherein the dead zone setting means is means for changing the width of the dead zone according to the magnitude of the value of the touch data. 3. The dead zone setting means takes the touch data as an address input, and includes a memory circuit that reads out a dead zone setting value corresponding to the address value, and an adder that substantially adds the dead zone setting value and the touch data. means, the digital-to-analog conversion means is means for converting the touch data and the adder output into analog voltages, and the comparison means converts both the analog voltages from the conversion means and the sensor output. and the counting control means causes the counting means to add (or subtract) a certain value if the sensor output voltage is higher than both analog voltages as a result of the comparison, When the sensor output voltage is lower than both analog voltages, the counting means subtracts (or adds) a certain value, and when the comparison results between the sensor output voltage and both analog voltages do not match, the counting means subtracts (or adds) a certain value. The key touch data generation circuit according to claim 1, which is means for holding the count contents of the means.