JPH053593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device that can easily perform digital processing and detect accurate touch speeds when keys are pressed in electronic musical instruments.

[Prior Art] Electronic musical instruments have come to be equipped with a touch response function for controlling volume and tone by detecting the speed of key depression (or it may be thought of as the pressure of key depression).

In conventional electronic musical instruments, there is a switch for key-on signals that controls musical tone generation in response to key presses and key releases;
Two switches are provided corresponding to one key with a key switch for obtaining a key press speed detection signal for the touch response. This device has a complicated configuration.
It had the disadvantage of being larger.

Attempts have therefore been made to provide only one key switch for each key. Figure 5 is an example of this.
This is a simplified diagram of the circuit described in Publication No. 79495. In Fig. 5, 11, 12...
...1n is a key switch provided corresponding to a key (not shown), 21 is a voltage Vcc application terminal,
22 is the voltage 1/4 Vcc application terminal, 23 is the voltage 3/4
Vcc application terminals, 31, 32, . . . , 3n are resistance elements having respective resistance values R, 41, 42, . . . , 4n are operational amplifiers, and 51 is an exclusive OR circuit. The switching contact 11c of the key switch 11 contacts the first contact 11a when the key is not pressed, and contacts the second contact 11b when the key is fully pressed. When the key is being pressed, the switching contact 11c is not in contact with either the first or second contacts. The first contact 11a is a voltage
It is connected to the Vcc application terminal 21, and the second contact 11b
is grounded. Further, one of the input terminals of the operational amplifiers 41 and 42 is commonly connected to the switching contact 11c, and the other is connected to the voltage application terminals 22 and 23.
Therefore, each output S1 of the operational amplifiers 41 and 42
1, S12 and the output S of the exclusive OR circuit 51
The relationship between No. 13 and the change in potential of the switching contact caused by key depression is shown in the time chart of FIG. The key release state continues from time T0, and then at time T1
Assume that the key press starts at . Switching contact 11
The potential of c has been Vcc until now, but it suddenly changes to 1/2Vcc. That is, since the contact 11c is not in contact with either the first or second contact, the resistor 3 having the resistance value R
The value is 1/2Vcc, which is obtained by dividing Vcc by 1 and 32. The output S11 of the operational amplifier 41 changes from "H" to "L". Switching contact 1 at time T2
1c is in contact with the second contact 11b, and the potential becomes the ground potential. The output S12 of the operational amplifier 42 changes from "H" to "L". Therefore, the output S13 of the exclusive OR circuit 51 changes from "L" to "H" only between times T1 and T2. In other words, the change in potential of the switching contact caused by key press operation is detected when the contact piece of the key switch 11 is not in contact with both the first and second contacts, so the length of this time is determined by the key press. It corresponds to the key speed.

When releasing the key, if time T3 is the start of key release and time T4 is the end of key release, the time between T3 and T4 is the key release operation time, as described above. Therefore, when it is necessary to detect the key release speed, T3 to T4
Measure between.

[Problems to be Solved by the Invention] In the circuit configuration shown in FIG. 5, it is necessary to use two operational amplifiers for determining voltage changes and to process multilevel signals. Furthermore, when rubber contact switches, which have become increasingly popular in recent years, are used as key switches, the contact resistance varies by several tens of ohms to 1k ohm, and circuits that compare multi-value signals cannot detect accurate speed values. difficult to do.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and to provide a touch speed detection device that has a simple configuration and can accurately detect signal changes at the switching contacts of a key switch as a result of key depression.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the means adopted in the present invention is to provide one switching contact and a first and second contact for each key of an electronic musical instrument. a key switch, a clock source and a pulse counter connected to a switching contact of the key switch, the first and second contacts having a lower impedance with respect to ground potential and different from each other than the switching contact; The switching contact is connected to an electric potential, and the switching contact is switched from contacting one of the first and second contacts to the other in response to each key operation, and the pulse counter outputs when the contact is switched. The touch speed is determined by detecting the touch speed.

[Function] When the key is released, the clock from the clock source is the first clock.
It is grounded to the low impedance side through the contact and does not reach the pulse counter. Further, even when the key is fully pressed, the second contact is connected to the DC power supply and the clock does not reach the pulse counter.
Since clocks can be counted for the time from the start to the end of a key press, the touch speed can be determined by digital processing in inverse proportion to the number of pulses.

[Embodiment] FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. In FIG. 1, 11, 12, . . . 1n are key switches provided corresponding to the keys of an electronic musical instrument (not shown), and 21 is a voltage Vcc application terminal, for example, a +5V integrated circuit voltage terminal. 11c is a switching contact, and the first contact 11a is switching contact 1 when the key is released.
1c and is at ground potential. Second contact 1
Since 1b is connected to the voltage Vcc application terminal 21,
It has low impedance to the ground point. Each second contact of the key switches 12, 12...1n also
Similarly, it is connected to the voltage terminal 21. Switching contact 11c
is released from contact with 11a by the key press operation, and comes into contact with the second contact 11b when the key press operation is completed. 6
7 is a pulse oscillator with a repetition frequency of, for example, 1 MHz, and 7 is a frequency divider that obtains a clock of several hundred Hz from its 1/2 frequency output terminal. 5
2, 53...5n are AND circuits and OR circuits in symbolic form normally used in logical operation circuits. 61,
62...6n is the connection resistance to the switching contact, 71,7
2...7n indicates a buffer circuit. 81, 82...
...8n is a D-type flip-flop constituting a latch circuit, 91 is a pulse counter, and 92 is a pulse counter output latch circuit.

The operation of each element will be explained using the time chart shown in FIG. The key switches 11, 12, . . . contact the first contact 11a at the key release time T0, and the switching contact 11c is at the ground potential, so it is at the "L" level. The outputs of the oscillator 6 and the frequency divider 7 are respectively φ ₁ ,
It is assumed that φ ₂ is _the output of the frequency divider 7 divided into 1/2. Since the potential of the switching contact 11c is grounded, the clock φ ₂ does not flow toward the latch circuit 81. When the key press starts at time T1, the switching bar of the switching contact 11c moves away from the first contact 11a and moves toward the second contact 11b in a known manner. If the key press ends at time T2, the switching lever comes into contact with the second contact 11b at this time. Therefore, the switching contact 11c is the first contact 11
a. While not touching any of the second contacts 11b (T
1 to T2), the ground impedance of the switching contact 11c becomes high, and the switching contact 11c begins to change its potential due to the clock _φ2 . Therefore, the clock φ ₂ is applied to the latch circuit 81.
At this time, the value of the connection resistor 61 is set as follows. That is, the value should be 1/10 or less of the input impedance of the latch circuit 81, and 10 times or more the contact resistance between the switching contact and the first or second contact. This is to prevent the level of the clock signal from affecting the operation described below.
Note that clock pulse counting will be described later.

When the key press is completed (after time T2), the switching contact 11c is connected to the low impedance side in terms of AC,
No potential change occurs due to clock. After the time T3 when the switching contact 11c shifts to the key release operation,
After the time when the key release operation starts, the time T when the key release is completed
Until 4, it only counts clocks and does not perform touch speed detection.

Next, clock pulse counting will be explained. The clock at the switching contact 11c is a latch circuit 81.
When applied to signal KY10, latch circuit 8
1, that is, the input of the latch circuit 82, as the signal KY1.
1. Let the output of the latch circuit 82 be the signal KY12. The signals KY11 and KY12 are logically operated by an OR circuit 53, and the result is set as KF1. Also KF1,
A logical operation is performed on KY11 and KY12 by an AND circuit 52, and the result is expressed as KN1. latch circuit 81,
Since the output _φ1 of the oscillator 6 is input as is to each clock input terminal CK of the latch circuit 82, the signal of the KY11 which is the output of the latch circuit 81 is obtained as shown in FIG. KY12 signal is latch circuit 8
Since it is obtained as the output of 2, KY11 is KY1
Compared to 0, it is delayed by clock φ ₁ , and furthermore, KY12 is
It is behind KY11 by _φ1 . Pulse counter 9
In No. 1, the KY12 signal is input to the clock CK terminal, and counting is performed at the timing of its rising edge.
The reset is input to the R terminal as is done when KF1 falls to "L".

The counter 91 has, for example, flip-flops connected in cascade, and the output terminals Q1, Q2, . . . of each stage.
Take out Qm, use KN1, latch circuit 9
Import in step 2. That is, since the signal KN1 rises after the key press is completed, if the pulse count result is latched at that time, the touch speed can be calculated as the reciprocal of the pulse count value.

In Fig. 1, a clock pulse counter is provided for each key switch to obtain a touch speed detection signal, but the counter and latch circuit are configured in a simple time-division calculation configuration using memory as shown in Fig. 3. can be taken as a thing. In FIG. 3, where there are 64 key switches, φ ₂ to φ ₇ sequentially represent the 1/2 frequency divided outputs of the frequency divider 7 in FIG. 1, 93 is a selector, 94 is a ROM, 95 and 96 are gates, 97 is an adder, and 98 is a first-in first-out memory (FIFO). Addresses in the ROM are determined in correspondence with 64 key switches, and are sequentially selected using φ ₂ to _{φ 7} . Figure 4 shows a time chart of the clock frequency division outputs φ ₁ to _{φ 7.} By combining φ ₁ to _{φ 7} ,
A selection address is obtained. The data stored at each address is, for example, a predetermined value such as 0000001 (the predetermined value may be different for the black key and the white key).
The clock frequency divider is set so that when a certain key switch is operated, the address is selected at least once from the start to the end of the operation.
Therefore, a certain key switch is operated and its output
KN and KF are selected by the selector 93 and become the Y output. During the time when the exclusive OR operation is performed on KN and KF, the output of the ROM 94 passes through the gate 95 and is added in the adder 97 to the previously calculated value output from the FIFO memory 98. Next, the inverted KF signal passes through the gate 96, and the M outputs of the FIFO memory 98 are composed of, for example, seven buses, and the output signals correspond to the touch speed data shown in FIG. The next address is selected by the change in the clock frequency division output, and when there is a key switch operation, the same operation occurs, and when there is no key switch operation, no change occurs in the touch speed output value.

[Effects of the Invention] In this way, according to the present invention, it is possible to accurately capture the signal change of the switching contact of the key switch due to the key press operation, so it is easy to digitally process it, and from that value, an effective touch response signal can be obtained. can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of an embodiment of the present invention, Figure 2 is a diagram showing the configuration of an embodiment of the present invention.
The diagrams are the operation time chart of each element in Figure 1, and the operation time chart of each element in Figure 3.
The figure shows a modified configuration of the counter and latch circuit in Figure 1, Figure 4 is an operation time chart of Figure 3, Figure 5 is a diagram showing the configuration of a conventional touch speed detection device, and Figure 6 is a diagram showing a modified configuration of the counter and latch circuit in Figure 1. This is an operation time chart of FIG. 5. 6... Oscillator, 7... Frequency divider, 11, 12...
1n... Key switch, 21... Voltage Vcc application terminal, 31, 32... 3n... Resistance element, 41,
42...4n...Operation amplifier, 51...Exclusive OR circuit, 91...Pulse counter, 92...Latch circuit, 11a...First contact, 11b...Second contact, 11c...Switching contact .

Claims (1)

[Scope of Claims] 1. A key switch provided for each key of an electronic musical instrument and having a switching contact and first and second contacts; a clock source and a pulse counter connected to the switching contact of the key switch; Compared to the switching contact, the first and second contacts are connected to a different potential with low impedance with respect to the ground potential, and the switching contact is connected to the first and second contacts in response to each key operation. A touch speed detection device for an electronic musical instrument, characterized in that the touch speed is switched from a contact state to one of the contacts to a contact state to the other, and the output of a pulse counter at the time of switching the contact is detected to determine the touch speed.