JPH02170717A - Switch input system - Google Patents

Abstract

PURPOSE:To prevent a malfunction even when a switch contact point is unstable by deciding that the switch is not turned off when the switch is turned on again in a time set beforehand even if the switch in turned-on condition is changed over to a turned-off condition. CONSTITUTION:A switch matrix 1 arranged in a matrix is connected through a bus line, etc., to main CPU 6, a ROM 7, and a RAM 8. When the switch condition is changed and restored to the original condition in a prescribed period, the changed-over condition of the switch is made null, and when the switch condition is restored after the prescribed period, the changed-over condition of the switch is made effective. Thus even when the contact condition of the switch is unstable, the malfunction is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a switch input method that prevents the occurrence of erroneous inputs due to chattering of switch contacts.

(Prior Art) As a switch input method that can prevent the occurrence of erroneous inputs even when switch contacts are unstable, a chattering prevention input method using a conventional scan method is known.

In this input method, as shown in FIG. 3, the state of the switch is monitored at regular time intervals to determine the on/off state.

For example, when the state of a switch changes from off to on, the state of the switch is captured again after a preset debounce period (for example, 10m5ec to 20m5ec), and when the current state is on, the switch is turned off for the first time. Determine the status as on.

The same applies when the state of the switch changes from on to off.

However, although such conventional switch input methods can effectively prevent malfunctions due to chattering during switch on/off, as shown in FIG. When the switch is turned on due to weakening (for example, period F), there is a problem in that the switch is once determined to be off during period F, even though the switch is turned on during period E.

Therefore, when the number of times the switch is turned on and off has a meaning, for example when inputting numerical data using the numeric keypad, incorrect data is input.

- For example, when manually inputting numerical data from the numeric keypad, the same key may be pressed many times in a short period of time, but in this case, the correct number of presses may not be entered and the key will turn on only once. A false judgment may be made, or an erroneous judgment may be made that it has been turned on for a long time. Such misjudgment caused incorrect data to be input.

Therefore, in order to eliminate this inconvenience, it may be possible to lengthen the debounce time (usually 10m5ec to 20m5ec), but in this case, the same switch must be held down for a long time to recognize the switch on, and the keyboard This not only hinders the speed up of operations, but also
Even if this is done, an erroneous input may occur when the switch state is retrieved again and the contact state of the switch is unstable.

(Object of the Invention) The present invention was made in view of the above circumstances, and an object of the present invention is to provide a switch input method that can prevent malfunction even when the contact state of the switch is unstable. There is.

(Summary of the Invention) In order to solve the above problems, in the switch input method according to the present invention, when the state of the switch returns to its original state within a predetermined period from the time when the state of the switch changes, the switch is switched. The switching of the switch is determined to be valid when the state of the switch returns to its original state after the predetermined period has elapsed.

(Embodiment) FIG. 1 is a block diagram showing an example of a system to which a switch input method according to the present invention is applied.

In the embodiment shown in this figure, a switch matrix 1 arranged in a matrix is connected to a main C through a pass line or the like.
PU6. This shows a case in which the present invention is applied to a system connected to a ROM 7 and a RAM 8, including a switch scan circuit 2 that scans this switch matrix 1 and captures the pressed state of each switch, and and a switch input processing section 3 that takes in information regarding the pressed state of the switch and performs chattering processing and contact unstable period removal processing, and the result of the operation of the switch matrix 1 is transmitted to the switch scan circuit 2 and the switch input processing section. 3 and a main C which executes processing based on the application program stored in this ROM 7 and the processing results of the switch input processing section 3.
The information is transmitted to the PU 6 and the RAM 8 used as a work area for the main CPU 6.

Here, the control described in detail below is executed by a logic circuit built in the switch input processing section 3 or by a simple CPU, but it may be executed by the main CPU 6 instead of this CPU.

The switch input processing section 3 includes a debounce timer 4 that measures debounce time, and a switch off timer 5 that measures the time from when a switch is turned off until it is turned on again.
When the switch is turned on from off, a debounce timer 4 is used to remove chattering, and when the switch is turned from on to off, a switch off timer 5 is used to remove unstable contact. Let's do it.

Next, the operation of the switch input processing section 3 described above will be explained with reference to the flowchart shown in FIG.

First, any switch in switch matrix 1,
For example, when "P71" is turned on, the switch input processing section 3 waits until it is detected by the switch scan circuit 2 (step S'I"l). Then, based on this detection result, the switch input processing section 3 When detecting that any switch, for example switch "'P", is turned on, it clears the debounce timer 4 and starts it (step 5T2).

When the debounce timer 4 times up (step 5T3), the switch input processing section 3 checks again whether the switch "P" is turned on (step 5T4), and if it is not turned on, turns it off. It is determined to be invalid and returns to the initial state.

Further, when the switch "PIT" is checked again, if it is on, the switch input processing section 3 determines that this state change is valid, and sends the switch "PIT" to a required part, for example, the main CPU 6 via the pass line. It is notified that II has been turned on (step 5T5).

After this, the switch input processing unit 3 waits until the switch "P", which has already been determined to be on, is turned off (step 5TY)
.

Then, if this switch "p II" is turned off.

The switch input processing section 3 clears the switch-off timer 5 and starts it (step 5T7).
, checks whether any switch in switch matrix 1 is turned on (step 5T9).
.

Here, if a switch other than "P" is turned on, the switch input processing section 3 returns to the above-described debounce removal processing (steps ST2 to 5T4) to turn on the switch that is currently turned on.

Furthermore, if the switch II PIT is turned on, the switch input processing unit 3 reads the value of the switch off timer 5 (step 5TIO) and checks whether this is longer than a preset time (for example, 100m5ec). Check step 5 (TII), if the value of the switch-off timer 5 is less than the set time, it is determined that the off of the switch "P II" is due to unstable contact of the contact, and the above-mentioned switch "'P" is turned off. The process returns to the off detection operation (step 5T6).

Further, if the value of the switch-off timer 5 is equal to or longer than the set time, the switch input processing section 3 determines that the switch "P" was turned off once and then turned on again, and performs the debounce removal process described above (steps ST2 to Returning to step 5T4), the currently turned on switch "P" is turned on.

As described above, in this embodiment, even if the switch in the switch matrix 1 is switched from on to off, if it is turned on again within a preset time, the switch will be turned off. Since it is determined that there was no such switch, even if the contact state of the switch becomes unstable, the number of on/off times of this switch can be accurately determined.

Furthermore, in the above-mentioned embodiment, the setting time is 100 m5.
Although ec is used, it is obvious that other values may be used depending on the type of switch and purpose of use.

It should be noted that the above description is only one embodiment of the present invention, and various modifications are possible, and the switch to be applied is not limited to a matrix type, but may also be implemented with a single switch.

(Effects of the Invention) As described above, according to the present invention, it is possible to prevent malfunction even when the contact state of the switch is unstable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a system to which an embodiment of the switch input method according to the present invention is applied, FIG. 2 is a flowchart showing an example of the operation of the same embodiment, and FIG. 3 is a conventional switch FIG. 4 is a waveform diagram for explaining an example of an input method. FIG. 4 is a waveform diagram for explaining problems with the conventionally known switch input method. DESCRIPTION OF SYMBOLS 1... Switch matrix, 2... Switch scan circuit, 3... Switch input processing part, 5... Switch off timer. Patent applicant: Toyo Tsushinki Co., Ltd.

Claims (1)

[Claims] (1) A switch input method characterized in that means is provided for measuring the time from the on state to the off state or from the off state to the on state, and when the time is less than a predetermined value, switching of the switch is disabled. .