JPH0335310A - Key input device and method - Google Patents

Abstract

PURPOSE:To prevent the simultaneous input of keys and to save the capacity of a memory by writing only a key code kept in an ON state and confirmed by a scan into the memory, scanning again the relevant key based on the key code, and discriminating an input key when a key kept in an ON state is detected. CONSTITUTION:In a key matrix scan state, only the code of a key kept in an ON state is written into a memory. Then only this key code is scanned again and therefore the 1st and 2nd key matrix scanning times can be shortened. When only a key b2, for example, is pushed, only the code of the key 12 is written into the memory with the 1st key scan. Then only the key 2b is scanned again and therefore the key matrix scanning time can be shortened. At the same time, only the code of the key b2 is written into a memory 13. Thus the memory capacity can be saved. When both keys b2 and b4 are pushed at one time, only the key b2 is accepted as an input key at the time point when the On state of the key b2 is judged. Meanwhile the key b4 is neglected. As a result, the simultaneous key input can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a key matrix key input device used in office automation equipment and the like.

Conventional technology The conventional technology will be explained with reference to FIGS. 4 to 6.

FIG. 4 is a block diagram of the input device, FIG. 5 is a flowchart explaining the processing operation of the microcomputer in FIG. 4, and FIG. 6 is a timing chart explaining the operation of the circuit in FIG. 4.

According to FIGS. 4 to 6, the conventional key input device includes a microcomputer 1, a key matrix 2, a memory 3, and a timer 4. The timer 4 is built into the microcomputer l.

The operation of the key input device configured as described above will be explained below. First, the key matrix 2 is scanned by the microcomputer 1. In other words, for each key, al,
a2, a3. . . . e3, e4, and e5 are scanned in this order, and all the results are written into the memory 3 as shown by the arrow (a) in FIG.

After all the keys have been scanned - times, a timer 4 is used to set a chattering prevention time and the scanning is stopped.

Next, the microcomputer 1 again sets the key matrix 2 to al,
Scan a2, a3, . Next, the result of the first key matrix scan shown in the arrow (C) in FIG. 4 written in the memory 3 is ANDed with the result of the second key matrix 1 scan shown in the arrow (d) in FIG. It calculates the input key based on the calculation result.

Problems to be Solved by the Invention However, in the conventional technology described above, all the keys in the key matrix are scanned twice and an AND operation is performed on each key, so it takes a long time to determine the input key. We had the challenge of becoming.

The present invention solves the above-mentioned conventional problems, and provides a key input device that can identify input keys in a short time, prevent simultaneous key input, and save memory capacity. This is what we are trying to provide.

Means for Solving the Problems In order to solve the above problems, the present invention includes a microcomputer, a key matrix, a memory, and a timer, and writes only the key code of the key in the ON state confirmed by scanning to the memory. The device is configured to rescan the ten keys based on the on-state key code, and to determine the input key when one on-state key is found during the rescanning.

Effect With the above configuration, only the key codes of the keys in the ON state are written in the memory during the first key matrix scan, and only the memorized key codes are scanned again, so the time of the first key matrix scan and 2
This makes it possible to shorten the time required for the second key matrix scan.

Embodiment Hereinafter, an embodiment of the present invention will be explained using the drawings of FIGS. 1 to 3. FIG. 1 is a block diagram of the present invention, FIG. 2 is a flowchart explaining the processing operation of the microcomputer 11 in FIG. 1, and FIG. 3 is a timing chart explaining the operation of the circuit in FIG. key b2
This is an example when is pressed.

In FIG. 1, the main body of the device is composed of a microcomputer 11, a key matrix 12, a memory 13, and a timer 14.
The timer 14 is built into the microcomputer 11.

The operation of the key input device of this embodiment configured as described above will be described below. The microcomputer 11 sets the key matrix 12 to al, a2, a3,... e
1% e2 and e3 are scanned in this order, and only the key code of the key in the on state is written into the memory 13. Next timer 1
4 provides a chattering prevention time. After the chattering prevention time ends, the on-state key code written in the memory 13 is read out from the memory 13, and only the keys with the read key code are rescanned. If the rescanned key is determined to be in the on state, only that key is considered as an input key.

For example, if you press the b2 key, al, a2. a3,...
...The keys are scanned in the order of b2, and when b2 is key scanned, as shown by the arrow (a) in Figure 1, b
The key code No. 2 is written into the memory 13.

After that, b3, b4, b5, ---- e3, e4,
The keys are scanned in the order of e5, and after the key matrix 12 has been completely scanned, a chattering prevention time is set by a timer 14. After the chattering prevention time has elapsed, the key code written in the memory 13 is read out as shown by arrow (b) in FIG. Here, the read key code is for key b2.

Next, key b2 is rescanned based on this key code. If the key b2 is on, b2 is determined as the input key, and if the key b2 is off, it is assumed that there is no input key and the key scan is terminated.

If b2 and b4 are pressed at the same time, the key codes of key b2 and key b4 will be written to the memory 13, respectively, but when rescanning, keys b2 and b4 will be scanned in that order, and as a result of rescanning, key b2 will be in the on state. If so, the key b2 is determined as the input key, and the rescanning ends without rescanning the key b4.

As described above, according to this embodiment, when only key b2 is pressed, only the key code of key b2 is written in the memory in the first key scan, and only key b2 is rescanned, thereby creating a key matrix. Scan time can be shortened.

Further, since only the key code of key b2 is written in the memory 13, the memory capacity used can be saved. Furthermore, if key b2 and key b4 are pressed at the same time, key b
2 is determined to be on, only key b2 is accepted as an input key, and key b4 is ignored, so simultaneous key inputs can be prevented.

Effects of the Invention As described above, the present invention writes only the key codes of keys in the ON state in the first key matrix scan into the memory, and rescans only the keys with the key codes written in the anti-chattering device memory. The key matrix scan time can be shortened and the memory capacity used for the key matrix scan can also be saved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a key input device in an embodiment of the present invention, FIG. 2 is a flowchart explaining the processing operation of the microcomputer in the embodiment of FIG. 1, and FIG. 3 is an operation of the embodiment of FIG. 1. FIG. 4 is a block diagram of a conventional key input device, FIG. 5 is a flowchart explaining the processing operation of the conventional microcomputer shown in FIG. 4, and FIG.
3 is a timing chart showing the operation of the conventional example shown in the figure.

Claims (2)

[Claims] (1) A key matrix, a memory that writes only the key codes of keys in the on state, scans all the keys in the key matrix, writes the key codes to the memory, and then writes the key codes to the memory. A key input device characterized by comprising a microcomputer that scans only the keys of the computer and determines the input key when it is deemed to be in an on state. (2) scanning the key matrix to detect the on state of the key; writing the key code of the key in the on state into memory; providing a certain pause time; and updating the key code written in the memory. A key input method comprising the steps of rescanning only the keys and determining the input key at the point when the key is deemed to be in the on state.