JP2682900B2 - Key matrix input system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key matrix input system used to identify a pressed key on a keyboard.

[Conventional technology]

In the conventional key matrix input system, as shown in FIG. 4, a plurality of lines forming one line group of the matrix are used to individually identify which of a plurality of keys provided on the keyboard has been pressed. Using a plurality of switch input lines that form the other line group of the timing signal line of the matrix, for example, key input operation is performed at intervals of 50 msec, and individual timing signals are sequentially input to each timing signal line. The state of the output and switch input line is detected and the position of the pressed key is identified.

However, in such a conventional method, individual timing signals are always generated sequentially for each interval,
Since the above-mentioned individual switch judgment is executed, a square wave is generated by the timing signal at the time of key input at each interval described above regardless of whether the individual switch is pressed. Such a square wave is a cause of noise in audio equipment.

Therefore, in the audio equipment field, it is necessary to reduce the generation of the square wave which causes the noise as much as possible.

[Problems to be solved by the invention]

The object of the present invention is to solve the problems in the prior art and to prevent the generation of noise to the audio device when the key input is executed in the key matrix input system, since the square wave is less generated. It provides a possible key matrix input system.

[Means for solving the problem]

The present invention adopts the following technical configurations in order to achieve the above object. That is, in a key matrix input system composed of a keyboard and a control means for discriminating a pressed key on the keyboard, an output for a plurality of timing signal lines forming one line group of the matrix is output. First step of making all active, second step of detecting the states of a plurality of switch input lines forming the other line group of the matrix
Step, a third step of sequentially outputting individual timing signals to each of the plurality of timing signal lines when at least one state of the plurality of switch input lines is active, the individual timing signal And a fourth step of detecting the plurality of switch input lines in synchronism with the output, and when none of the plurality of switch input lines is non-active in the second step, Performing the fifth step of returning to the first step without performing the above-mentioned third and fourth steps, returning to the first step after the completion of the fourth step, and returning to the plurality of steps in the second step. If the switch input line of is still active,
The key matrix input system is configured to perform a sixth step of returning to the first step without performing the third and fourth steps.

[Action]

According to the present invention, by adopting the above-mentioned configuration, a square wave is conventionally generated at every interval of key input, whereas the state of key input is detected during a period of key input. And the step of outputting an individual timing signal to detect which key is pressed. First, in the step of detecting the state of the switch input line, if no key is pressed, an individual key is pressed. Since the step of outputting the timing signal is omitted, the generation of the above-mentioned square wave is reduced accordingly, and the generation of noise can be suppressed.

〔Example〕

Hereinafter, a specific example of the key matrix input system according to the present invention will be described in detail with reference to the drawings.

As described above, the key matrix input system according to the present invention is a key matrix input system including the keyboard 1 and the control means 2 for discriminating the pressed key on the keyboard. A first step of activating all outputs to a plurality of timing signal lines 3 forming one line group, and a second step of detecting the states of a plurality of switch input lines 4 forming the other line group of the matrix A third timing signal line is sequentially output to each of the plurality of timing signal lines when at least one state of the plurality of switch input lines is active.
And the fourth step of detecting the plurality of switch input lines in synchronization with the output of the individual timing signals, and in the second step, any of the plurality of switch input lines is performed. When it is non-active, it is a key matrix input system configured by performing a fifth step of returning to the first step without performing the above-mentioned third and fourth steps, and the outline of the configuration is It is shown in FIG.

In FIG. 1, the keyboard 1 is a 4 × 2 key matrix, that is, four timing signal lines 3 ₁ ,
An example is shown in which one line group 3 composed of 3 ₂ , 3 ₃ and 3 ₄ and the other line group 4 composed of _two switch input lines 4 ₁ and 4 _{2 are} composed. However, the present invention is not limited to a keyboard having such a configuration, and 4 ×
A keyboard of any configuration such as 4, 8 × 4 can be used.

Further, the control means used in the key matrix input system in the present invention means, as will be described later, a plurality of line groups 3 ₁ , 3 ₂ , 3 ₃ , 3 _4, etc. that constitute _one line group of the matrix. A circuit configured to sequentially output timing signals T ₀ , T ₁ , T ₂ , T ₃ to each of the timing signal lines 3 at appropriate intervals, the other line groups 4 ₁ , 4 _{2 of the} matrix. Switch input lines 4 that make up the
And a control judgment circuit for discriminating which key is pressed from the information of the switch input line detection circuit 7 at the same time as the detection circuit 7 for detecting the state of the switch and the control for sequentially outputting the timing signal at a predetermined interval. 8 is included at least, and the control means 2 usually constitutes one chip and is preferably constituted by a so-called microcomputer.

Conventionally, as shown in FIG. 4 in the circuit of FIG. 1, the timing signal line 3 is used to determine which key is pressed by inputting a key at a predetermined timing. ₁ , 3, ₂ , 3 ₃ , 3 ₄ are set in a non-active state in advance, that is, for example, in an L (low) state, and each of the timing signal lines 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ is The individual timing signals T ₀ , T ₁ , T ₂ , and T ₃ are output with their phases shifted.

On the other hand, as shown in FIG. ₁ , the switch input lines 4 ₁ and 4 ₂ have a node portion grounded through resistors R ₁ and R ₂ near the input portion of each line to the control means 2. Since it is provided, normally, that is, when there is no pressed key, the outputs K1 and K2 of the switch input lines 4 ₁ and 4 ₂ are non-active, that is, in the L (low) state, When any key on the key matrix is pressed, the switch input line in which the pressed key exists
Any of the inputs K 1 or K ₂ of 4 ₁ or 4 ₂ is in an active state, for example, H (high) state when the individual timing signal is keyed in, so which key is at which position? It is possible to determine whether it has been pressed.

In view of the above-described problems in the conventional method according to the present invention, in order to solve the above problems, when the conventional key input is performed, the timing signal line 3 While the output level is always inactive, it is always active, for example, in the H (high) state.

On the other hand, since the switch input line has the same configuration as the conventional one, at the time of normal operation, that is, when no key is input and when no key is pressed, each timing signal line 3 Each of the timing signal outputs T ₀ , T ₁ , T ₂ , T ₃ of ₁ , 3 ₂ , 3 ₃ , 3 ₄ is in the active or H state, but the switch input line,
The outputs K1 and K2 of 4 ₁ and 4 ₂ are non-active, that is, L
It is in the (low) state.

On the other hand, in such a configuration, when at least one key is pressed, the output K1 and / or K2 of the switch input line is output.
Becomes active, that is, in the H state.

Therefore, from this relationship, it is not possible to determine which key has been pressed, but it is possible to determine only some key has been pressed.

Therefore, in the present invention, first, the levels of the outputs K1 and K2 of the switch input line are detected, and if none of them are inactive, it is determined that none of the keys of the keyboard are pressed, and the conventional method Individual timing signals such as
_{T 0, T 1, T 2} , whether T ₃ to generate with pressed key is present, its position say somewhere if there stops the execution of the individual decision operation, for the next detection Do nothing until the key input timing signal is generated.

Therefore, it is possible to reduce the generation of a square wave due to a large number of timing signals as in the conventional case.

Next, in the present invention, the output of the switch input line
If at least one of the K1 and K2 levels is active, it is determined that one of the keys on the keyboard has been pressed,
Separate timing signals T ₀ , T ₁ , T ₂ , T ₃ as in conventional methods
Is sequentially generated to determine the location of the pressed key.

Then, when the location of the pressed key is confirmed, the detection operation is terminated and the outputs T ₀ , T ₁ , T ₂ , T ₃ of the timing signal line are all returned to the active state, and the next key input is performed. It will wait until the timing signal is input.

The waveform and timing of each output related to the operation
Shown in the figure.

That is, assuming that the key input timing signal is input at time t1, the timing signal lines 3 ₁ , 3 ₂ , at that time,
Timing signal output of each of 3 ₃ and 3 ₄ T ₀ , T ₁ , T ₂ , T ₃
Are both active, that is, in the H state.

Since the output levels of the outputs K1 and K2 of the switch input line are both inactive, the key matrix input system does not perform the work of determining which key is pressed at the time of the key input.

Next, at the time t2, when the next key input timing signal is input, if the key at the intersection of the timing signal line 3 ₃ of the key matrix and the switch input line 4 ₁ is pressed, the timing is Signal line 3 ₁ ,
Timing signal outputs T ₀ , T ₁ , and 3 ₂ 3 _{3 4} respectively
Both T ₂ and T ₃ are active, that is, in the H state, but the level of K1 of the switch input line is active, that is, H, and the level of K2 of the switch input line is non-active.

Therefore, the key matrix input system of the present invention determines that any key of the keyboard has been pressed and outputs the same individual timing signal as in the conventional method to confirm the position of the pressed key. Perform the operation of.

That is, the active output level of the individual timing signal T ₀ for the timing signal line 3 ₁ at time t2-1,
That is, H.

However, at this point, the outputs K1 and K2 of the switch input line
The output levels of are all inactive.

Next, activate the individual output level of the timing signal T ₁ for the timing signal line 3 ₂ at time t2-2, that is, the H.

However, even at this time, the outputs K1 and K2 of the switch input line
The output levels of are all inactive.

Active individual output level of the timing signal T ₂ for the timing signal line 3 ₃ At a time t2-3, that is, the H.

At that time, since the key at the intersection of the timing signal line 3 ₃ and the switch input line 4 ₁ is pressed, the output level of the switch input line output K1, becomes active and the output of the switch input line K2 becomes The output level is non-active.

Therefore, the position of the pressed key can be confirmed at this time.

The active output level of the individual timing signal T ₃ for the timing signal lines 3 ₄ at time t2-4, i.e. H
And

However, even at this time, the outputs K1 and K2 of the switch input line
The output levels of are all inactive.

At time t2-5, the operation of discriminating the pressed key by the above individual timing signal is finished, but since the key input timing is continued until time t3, the switch input line is output.
The K1 output level remains active.

Then, when a new key input timing signal is input at time t3, the same operation as described above is repeated to determine the pressed key.

That is, in the present invention, at the timing 1, the step A of detecting only the levels of the outputs K1 and K2 of the switch input line is executed, and the result is that both the levels of the outputs K1 and K2 are non-active. Since it is present, the subsequent operation is not executed and the next timing signal is input. On the other hand, at timing 2, step A for detecting only the levels of the outputs K1 and K2 of the switch input line is executed, and the result is the output.
Since the level of K1, which is one of the levels of K1 and K2, is active, the discriminating operation B of the pressed key is executed using the individual timing signal.

At timing 3, no key is pressed, so the same operation as at timing 1 is performed.

 A flow chart of the above process is shown in FIG.

That is, in FIG. 3, when the key input timing signal is first input, the timing signal outputs T ₀ , T ₁ , T ₂ , T _{3 of} the timing signal lines 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ respectively. Are both active, that is, in the H state. (Step a) Subsequently, it is determined whether or not at least one of the output levels of the outputs K1 and K2 of the switch input lines 4 ₁ and 4 ₂ is active. (Step b) In the process, output of switch input lines 4 ₁ and 4 ₂
If any of the output levels of K1 and K2 is non-active, go back to (step a), and if either of the outputs K1 and K2 of the switch input lines 4 ₁ and 4 ₂ is active, Proceeding to (step c), individual timing signals are output to the respective timing signal lines 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ . Then to determine the location of the pressed key by detecting the output of the output K1, K2 of the switch input lines 4 _1, 4 ₂ In (step d).

It is judged whether or not such individual timing signal is executed for each of all the timing signal lines 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ , and if not executed for all of them,
Returning to (step c), when the execution is completed, all the timing signal outputs T ₀ , T ₁ , T ₂ , T ₃ to the timing signal lines 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ are active, that is, H (Step f) and (step a).

〔effect〕

According to the present invention, it is possible to obtain a key matrix input system capable of preventing the generation of noise in an audio device when the key input is performed in the key matrix input system, since the above-mentioned square wave is less generated.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the outline of a key matrix input system according to the present invention. FIG. 2 is a diagram showing an example of a waveform diagram when the key matrix input system according to the present invention is executed. FIG. 3 is a flow chart showing the processing procedure of the key matrix input system according to the present invention. FIG. 4 is a diagram for explaining the operation of the conventional key matrix input system. 1 ... keyboard, 2 ... control means, 3 ... timing signal line, 4 ... switch input line.

Claims (1)

(57) [Claims] 1. A key matrix input system comprising a keyboard and a control means for discriminating a pressed key on the keyboard, and a plurality of timing signal lines constituting one line group of the matrix. , A second step of detecting the states of a plurality of switch input lines forming the other line group of the matrix, and a state of at least one of the plurality of switch input lines. Third step of sequentially outputting individual timing signals to each of the plurality of timing signal lines when is active, and detecting the plurality of switch input lines in synchronization with the output of the individual timing signals. Perform steps 4 and
A fifth step of returning to the first step without executing the third and fourth steps when none of the plurality of switch input lines is non-active in the second step After the completion of the fourth process, the process returns to the first process and the second process
When the plurality of switch input lines continue to be active in the step of, the sixth step of returning to the first step without performing the third and fourth steps is executed. Key matrix input system consisting of.