JPH0627953A - Chattering removal system for electronic musical instrument - Google Patents

Abstract

PURPOSE:To prevent malfunction in processing due to an output signal by ignoring chattering if the chattering ends before a counter reaches a specified value and preventing the chattering from appearing in the output signal even if the chattering is caused when a key switch is turned ON or OFF. CONSTITUTION:A CPU 20 detects the key switch being operated by scanning a key switch matrix 10, removes the chattering, and outputs information on a single tone to a musical sound generating circuit 50. A ROM 20 is stored with a program for operating the CPU 20 and a RAM 40 is stored with temporary information generated in the processing of the CPU 20, the contents of a key memory, and the value of the counter. The chattering removal of key switches assigned for sound generation among plural key switches is exclusively performed to securely remove the chattering by the easy method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chattering removing system for an electronic musical instrument in which chattering does not appear in an output signal when the key switch of the electronic musical instrument is turned on and off.

[0002]

2. Description of the Related Art Conventionally, a switch used for a keyboard or the like is accompanied by chattering. As a circuit for preventing this, for example, the configuration of FIG. 1 is used. 2A to 2H are operation waveform diagrams thereof.

In FIG. 1, a switch signal turned on / off by a switch (SW) 1 is a sampling clock CK.
1 and 4 into a serial-in-parallel-out type shift register 2 ₁ to 2 ₄ , input is S0, and outputs are S1 to S4. The output of the logical product of these outputs by the AND circuit 3 is S5, and the output of the logical sum of the OR circuit 4 is S6. That is, S5 outputs "1" when "1" is detected following four samplings, and S6 outputs "1" when "1" is detected even once in four samplings. . Although this example relates to a switch signal that is not time-division multiplexed, the same logic can be applied even if it is time-division multiplexed. The control circuit (CPU) used here is shared with the electronic musical instrument.

The operation waveforms in this case are shown as follows: Chattering at the time of key-on and key-off of the input S0 in FIG.
Corresponding to the clock CK1 in the same figure b, the outputs S1 to S4 of the shift registers 2 ₁ to 2 ₄ in the same figures a to f operate as shown in the figure, but in S5 in the figure g, the waveform a is h's S6
Then, the waveform b remains, which causes a malfunction.

[0005]

That is, when chattering occurs for a length longer than the time obtained by multiplying the number of stages of the shift register and the sampling period, the chattering prevention circuit outputs again at the width of the sampling period. Will occur.

Further, it is a great work to remove chattering as described above for the number of key switches. In particular, with an electronic musical instrument in which only a single tone is assigned to the sound source circuit at a time, the above method is wasteful.

An object of the present invention is to provide an efficient chattering removal process by selectively performing chattering removal on a key switch assigned for sounding when an on / off operation of a plurality of key switches of an electronic musical instrument is performed. Is.

[0008]

In order to achieve the above object, a chattering removing method for an electronic musical instrument according to the present invention scans a plurality of key switches arranged in a matrix to detect an operated key, and outputs a single tone. In an electronic musical instrument which outputs a key-on or key-off signal so as to sound, a key scanning means (step 1) for sequentially scanning the plurality of key switches, and an instruction to start and end the production of a single tone based on the result of the key scanning. The assigning means (steps 4 to 15), the counting memory N for storing the count value, and the counting means (step 3) for periodically counting the contents of the counting memory, the assigning means When a new key-on event is detected when no sound is generated (step 6), the count value is initialized and the new key-on is set to the single note. The first means (step 7) for applying the corresponding key-on signal and the key-off event of the musical tone assigned to the single note are detected (step 9), and wait for the count value to reach a predetermined value (step 9). Step 11) Second outputting a corresponding key-off signal
Means (step 12) and a third means (step 14) for controlling the sounding envelope to be attenuated at high speed when a new key-on event is detected while the musical tone assigned to the single note is being released (step 14). 15)
It consists of and. The numbers in parentheses indicate the correspondence with the flow chart described later.

[0009]

The chattering can be reliably removed by a simple method by exclusively performing the chattering removal of the key switch assigned to the tone generation among the plurality of key switches.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, for the sake of simplicity, it is assumed that information obtained by scanning a key switch is prioritized first and only one note is sounded.

FIG. 3 is a block diagram showing an embodiment of the present invention in a block form.

The key switch matrix 10 is a group of key switches configured as shown in the table below. CPU
As shown in the flow chart of FIG. 4, reference numeral 20 scans the key switch matrix to detect the operation of the key switch, removes chattering and outputs single tone information to the tone generation circuit 50. The ROM 30 stores a program for operating the CPU 20. RAM40 is CPU2
It stores temporary information generated in the process of 0, the contents of the key memory described later, and the value N of the counter. The tone generation circuit 50 is a device that electronically generates a tone as a single tone.

FIG. 4 is a flow chart of an example in which the same switch signal detection method as that described above is applied to the key switch matrix 10 of the electronic organ shown in FIG. 5a to 5g show the operation waveform diagrams. In FIG. 4, the time for one round of the flow is one cycle. Now, in order to detect the change of the key switch in the flow, that is, the event, the RA of FIG.
It has a key memory area in M40 and is read at time division multiplexed channel addresses S0 to S11 shown in the table below.

[0014]

[Table 1]

In this key memory, there is a "1" only for the key switch that is currently sounding. Therefore, in this case, since the sound generation channel is limited to one channel, "1" is only hit at one place. N indicates the value of the counter.

The flow of operation will be described below. Step 1
Output the key scan address with. Since it is time division multiplexing, there are S0 to S11 as shown in the table, and the bit number of the switch information in the address is selected. Next, in step 2, it is checked whether N (counter value) is 4 or more. If not (N = 0, 1, 2, 3), go to step 3 and increment the value of N, then step Go to 4. When N is 4 or more, jump directly to step 4. In step 4, the information corresponding to the address scanned this time is received, and it is checked whether the key is on. If the key is on, go to step 5 and the sound channel is currently in use (USE =
Check if 1) and if not in use, step 6
Go to and see if there is a change between the contents of the key memory and the currently scanned keyswitch information. That is, it is checked whether the key was off when the key switch was last scanned. If there is a change, go to step 7,
At the same time as updating the contents of the key memory, the value of N is set to "0" (zero), the key output signal is output in the ON state "1" through the tone generation channel, the process goes to step 16, and the process returns to the beginning.

When it is determined that the key is off in step 4, the process goes to step 8, and it is checked whether the information of the same key is written in the tone generation channel. If it is written, the process goes to step 9, Check whether there is a change (key event) between the contents of the key memory and the currently scanned key switch information. If there is a change, go to step 10, turn off the key memory and set the value of N to "0".
(Zero) and go to step 16. If there is no key event in the check of step 9, go to step 11 and N
Is 4 or more, and if so, go to step 12 and output the key output signal in the off state "0" through the tone generation channel and go to step 16.

If the tone generation channel is in use (USE = 1) from the check in step 5 when the key is on, step 1
Go to 3 and check whether the information of the same key is written in the pronunciation channel. If it is written, go to step 6. If not, go to step 14 and release the pronunciation channel. Check whether it is in a state. If it is not in the release state, it means that the sound has already been pronounced, so the process goes to step 16 without processing. On the other hand, in the release state, the process goes to step 15, and in order to express the player's key selection as faithfully as possible, the envelope generator is requested through the sound generation channel to release the sound which is sounded in the release state even with the key off at high speed. .

5a to 5g show operation waveforms when the present invention is applied to a key switch of an electronic organ.

FIGS. 3A, 3B and 3C show a procedure for obtaining a signal sampled by a sampling clock for a key switch signal having chattering when the key is turned on and off. Next, this signal is stored in the key memory to obtain the waveform shown in FIG. 7D, and the key event shown in FIG. 7E is detected from the change between this signal and the sampled signal shown in FIG. Since this key event corresponds to on / off of chattering, the method of giving a constant value N = 4 to the counter of the present invention is applied to this. That is, as shown in fN and g key-on / off waveforms in the same figure, the counter repeats N = 4 at the time of key-off, counting from "0" at the key event of the rising chattering at the time of key-on and "0" at the time of off. Is reset to.

The key-on state is maintained in the range of N = 0, 1, 2, 3, and N = 4 is repeated in the completely on state. Similarly, chattering at the time of key-off also holds the key-on state, and after the end, the key-off state occurs at N = 4.

In this case, the procedure leading to the final key-off and key-on in relation to the value of N, the key event, and the state of the key memory is as shown in FIG.

[0023]

As described above, according to the present invention,
Even if chattering occurs when the key switch is turned on and off, if it ends before the counter reaches a certain value, it will be ignored and not displayed in the output signal, so that malfunctions in processing by the output signal can be completely prevented. It is possible. Therefore, the chattering can be surely removed by a simple method by exclusively performing the chattering removal of the key switch assigned to the sound generation among the plurality of key switches.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a conventional example.

FIG. 2 is an operation waveform diagram.

FIG. 3 is a configuration diagram of an embodiment of the present invention.

FIG. 4 is a flow chart of an embodiment of the present invention.

FIG. 5 is an operation waveform diagram.

[Explanation of symbols]

 1 switch 11 3 stage counter 12 AND gate

Claims (1)

[Claims] 1. An electronic musical instrument that scans a plurality of key switches arranged in a matrix to detect an operated key and outputs a key-on or key-off signal so as to generate a single tone. A key scanning means for sequentially scanning, an assigning means for instructing start and end of sounding of a single tone based on the result of the key scanning, a counting memory for storing a count value, and a count for periodically counting the contents of the counting memory. The assigning means initializes the count value when a new key-on event is detected when the single note is not sounded, and assigns the new key-on to the single note and outputs a corresponding key-on signal. And a key-off event of a musical tone assigned to the single note, the count value reaching a predetermined value. Second means for waiting and outputting a corresponding key-off signal; and third means for controlling so that the envelope being sounded is attenuated at high speed when a new key-on event is detected while the musical tone assigned to the single note is being released. A chattering removing method for an electronic musical instrument, characterized by comprising: