JP7625354B2 - Device to prevent push button switch malfunction - Google Patents

Description

The present invention relates to a malfunction prevention device, and in particular to a malfunction prevention device suitable for preventing the continuous output of an activation signal when a push button switch is repeatedly pressed erroneously.

One known means for preventing malfunction of operation buttons in electronic devices is disclosed in, for example, Patent Document 1. The malfunction prevention device disclosed in Patent Document 1 inputs an operation signal of a specific key that locks key operation to a CPU, and counts the time that the operation signal is input to this CPU (operation time) with a timer, thereby determining whether the operation of the specific key is due to a human operation or due to a factor other than human operation (malfunction), and locks or unlocks the key, etc.

A malfunction prevention device configured in this way is believed to be able to prevent a malfunction that causes the key lock to be released and a normal operation key to be pressed, which would activate the electronic device and consume power. However, the malfunction prevention device disclosed in Patent Document 1 uses a CPU and a timer to determine the operation state of the keys. This means that the CPU continues to consume power even when no keys are being operated. Patent Document 1 also describes a sleep mode that pauses CPU operation, but because a timer is used to count the time that a specific key is operated when the sleep mode is released, it is unclear what state the CPU is in when it is paused.

Such malfunction prevention devices are considered to be effective for devices in which the battery is expected to be charged in a short period of time, such as one to several days. However, in small remote controls that are expected to operate for several months using a small-capacity battery such as a button cell, the operating power of the CPU itself, such as that of the malfunction prevention device disclosed in Patent Document 1, can account for a large proportion of power consumption.

JP 2004-273077 A

The present invention aims to provide a device for preventing malfunction of a push button switch that can stop the supply of power when the button is pressed by mistake, and can reduce standby power consumption without relying on the CPU to determine whether the button has malfunctioned.

The device for preventing malfunction of a push button switch according to the present invention, which is intended to achieve the above object, is a switch circuit having a power supply start circuit between a battery and an operating power source, which prompts the supply of power from the operating power source to a control unit, and a charge/discharge circuit is provided between the power supply start circuit and the button switch, and the power supply start circuit is configured to pass a start current to the operating power source when a potential difference of a predetermined value or more occurs between the voltage between the battery and the power supply start circuit and the voltage between the power supply start circuit and the push button switch when the button switch is pressed, and the charge/discharge circuit is configured to determine the time for which the start current flows when the push button switch is pressed by setting a time constant for transitioning from a transient state to a steady state.

In addition, in the push button switch malfunction prevention device having the above characteristics, the charge/discharge circuit can be a circuit in which a resistor and a capacitor are arranged in parallel. By having such characteristics, it is possible to arbitrarily determine the time constant by setting the resistance value and the capacitance of the capacitor.

In addition, the power supply start circuit in the device for preventing malfunction of a push button switch having the above-mentioned characteristics is a PNP type transistor having a base resistor, the battery is connected to the emitter side, the charge/discharge circuit is connected to the base side, and the resistance value of the base resistor is preferably set to be smaller than the resistance value of the resistor that constitutes the charge/discharge circuit.

Furthermore, the power supply start-up circuit in the push button switch malfunction prevention device having the above-mentioned characteristics is a FET having a gate-source resistor, the battery is connected to the source side, and the charge/discharge circuit is connected to the gate side, and the resistance value of the gate-source resistor can be set to be smaller than the resistance value of the resistor that constitutes the charge/discharge circuit.

With a push button switch malfunction prevention device having the above characteristics, the power supply can be stopped after a specified time has elapsed even if the button is pressed. In addition, there is no need to rely on the CPU to determine if the button has malfunctioned. This makes it possible to reduce standby power consumption compared to conventional methods.

1 is a diagram showing a schematic configuration of a small remote control to which a push button switch malfunction prevention device according to an embodiment is applied; 1 is a diagram for explaining the configuration of a push button switch malfunction prevention device according to a first embodiment; 13A to 13C are diagrams for explaining the configuration of a push button switch malfunction prevention device according to a second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a push button switch malfunction prevention device according to the present invention will be described in detail with reference to the drawings.
[composition]
The push button switch malfunction prevention device according to this embodiment (hereinafter simply referred to as the malfunction prevention device 10) is applied to a portable small remote control, and the push button switch may be, for example, an operation button such as a button for locking/opening a vehicle key, a button for opening/closing a door, or a button for starting an engine. Fig. 1 is a schematic diagram showing the configuration of a small remote control 50 to which the malfunction prevention device 10 according to the embodiment is applied. As shown in Fig. 1, the small remote control 50 has at least a battery 12, an operating power source 20, a power supply starting circuit 14, a button switch 18, a charge/discharge circuit 16, a control unit 30, and a power supply holding circuit 40.

The battery 12 may be a primary battery such as a button battery or a rechargeable secondary battery, and is an element that supplies power resulting from button operation to the control unit 30, operating power source 20, etc. via the power supply start circuit 14 when the button switch 18, which will be described in detail later, is pressed.

The operating power source 20 is an element that supplies the power required to output operation signals for various operations to the control unit 30, which will be described in detail later, and outputs the power based on the power supplied from the battery 12.

The power supply startup circuit 14 is a startup circuit for facilitating the supply of power from the operating power supply 20 to the control unit 30. When the current from the battery 12 flows through the path on the button switch 18 side, the supply of power to the operating power supply 20 side is prompted, and the operating power supply 20 starts up.

The button switch 18 is a button for executing various functions using the compact remote control 50. Although the example shown in FIG. 1 shows a single button switch 18, multiple button switches 18 may be provided. When multiple button switches 18 are provided, it is desirable to provide them so that they are connected in parallel to the secondary side of the charge/discharge circuit 16, the details of which will be described later. This is because, with such a configuration, it is possible to ensure the functionality of the charge/discharge circuit 16 while maintaining a single charge/discharge circuit 16.

The charge/discharge circuit 16 is an element for controlling the current supplied to the button switch 18 side path via the power supply start circuit 14. When the charge/discharge circuit 16 is in a charging state (transient state), a potential difference occurs between the path of the battery 12-power supply start circuit 14 and the path of the charge/discharge circuit 16-power supply start circuit 14, so power is supplied to the charge/discharge circuit 16 side, i.e., the path on the button switch 18 side. On the other hand, when the charge/discharge circuit 16 reaches a charging completion state (steady state), there is almost no potential difference between the above two paths, and the power supply to the button switch 18 side path is stopped (becomes extremely small). Therefore, even if the button switch 18 continues to be pressed, the power supply to the button switch 18 side path is stopped, making it possible to reduce power consumption.

The control unit 30 is an element, such as a microcomputer, that performs the determination process for executing various functions and outputs control signals. The control unit 30 receives power from the button switch 18 side path and from the operating power source 20, and uses this as an input signal to determine the required control and output control signals, etc.

The power supply holding circuit 40 is an element that prevents the power supply to the operating power source 20 from being stopped by the action of the charge/discharge circuit 16 when the control unit 30 is operating. Based on a control signal from the control unit 30, the power supply holding circuit 40 lowers the potential of the charge/discharge circuit 16 side path in the power supply starting circuit 14, and performs an action equivalent to a pseudo power supply to the charge/discharge circuit 16 side path. This allows power to be supplied to the operating power source 20 via the power supply starting circuit 14.

In the compact remote control 50 having such a basic configuration, the malfunction prevention device 10 according to the present invention is composed of a battery 12, a power supply starting circuit 14, a charging/discharging circuit 16, and a button switch 18. The specific form of the malfunction prevention device 10 composed of these elements will be described below.

[First embodiment]
2, a PNP type transistor is used in the power supply starting circuit 14, and the charge/discharge circuit 16 is configured by connecting a resistor 16a and a capacitor 16b in parallel. The power supply starting circuit 14, which is configured by a transistor, is provided with a base resistor 14a and a base-emitter resistor 14b.

The resistance value of the base resistor 14a is configured to be sufficiently smaller than the resistance value of the resistor 16a that constitutes the charge/discharge circuit 16 (about 1/10 in the example shown below). This configuration makes it possible to balance the charging and discharging in the charge/discharge circuit 16, and to reduce the time constant until the charge/discharge circuit 16 transitions from a transient state to a steady state. The capacity of the capacitor 16b that constitutes the charge/discharge circuit 16 can be determined so as to obtain the desired time constant, taking into consideration the resistance value of the resistor (base resistor 14a) associated with the transistor and the resistance value of the resistor 16a that constitutes the charge/discharge circuit 16.

As an example, if the resistance value of the base resistor 14a is 100 kΩ and the resistance value of the resistor 16a that constitutes the charge/discharge circuit 16 is 1 MΩ, then by setting the capacitance of the capacitor 16b to 1 μF, the charge time constant will be 0.1 seconds and the discharge time constant will be 1 second (time constant T = CR: C = capacitor capacitance, R = resistance value).

[Action]
When the malfunction prevention device 10 is configured in this way, the following action is achieved by pressing the button switch 18. First, when the button switch 18 is pressed, a current flows from the emitter side to the base side of the transistor that constitutes the power supply starting circuit 14, and the current is supplied to the charge/discharge circuit 16. At this time, the current from the battery 12 also flows to the operating power supply 20 located on the collector side.

When the button switch 18 is pressed and the capacitor 16b that constitutes the charge/discharge circuit 16 is charged, the potential difference between the emitter circuit and the base circuit disappears (becomes small), and the flow of current from the emitter side to the base side stops. This also stops the supply of power from the collector side.

[effect]
As a result, even if the button switch 18 is kept pressed, the current flowing to the circuits on the receiving side, such as the control unit 30, is cut off, making it possible to reduce power consumption. Furthermore, the cutting of the current to the circuits on the receiving side, such as the control unit 30, is based on a change in potential between the charge/discharge circuit 16 and the power supply start-up circuit 14 and does not involve control by the CPU or the like, making it possible to reduce the power consumed by the CPU or the like.

[Second embodiment]
Next, a configuration in which a FET is used in the power supply starting circuit 14 will be described with reference to Fig. 3. When the power supply starting circuit 14 is configured with a FET, the battery 12 is connected to the source side, the button switch 18 to the gate side, and the operating power supply 20 to the drain side. In the example shown in Fig. 2, a gate-source resistor 14c is provided.

The charging/discharging circuit 16 may be configured with a resistor 16a and a capacitor 16b, similar to the case where a transistor is used in the power supply starting circuit 14 (the configuration shown in FIG. 2). Here, the resistor 16a is set to have a resistance value that is sufficiently larger than the resistance value of the gate-source resistor 14c in the FET that constitutes the power supply starting circuit 14 (for example, 10 times).

[Action and Effects]
Even if the malfunction prevention device 10 is configured in this manner, as with the malfunction prevention device of the above embodiment, the current flowing to the control unit 30 is cut off even if the button switch 18 is continuously pressed, thereby making it possible to reduce power consumption.

In the above embodiment, a vehicle operation remote control was used as an example of a small remote control 50 to which the malfunction prevention device 10 is applied, but the push button switch malfunction prevention device 10 of this embodiment can also be applied to remote controls used for other purposes.

10: Malfunction prevention device, 12: Battery, 14: Power supply start circuit, 14a: Base resistor, 14c: Gate-source resistor, 16: Charge/discharge circuit, 16a: Resistor, 16b: Capacitor, 18: Button switch, 20: Operating power supply, 30: Control unit, 40: Power supply maintenance circuit, 50: Small remote control.

Claims (4)

A switch circuit having a power supply starting circuit between a battery and an operating power supply, the power supply starting circuit urging a supply of power from the operating power supply to a control unit,
A charge/discharge circuit is provided between the power supply starting circuit and the button switch,
the power supply starting circuit is configured to supply a starting current to the operating power supply when a potential difference of a predetermined value or more is generated between a voltage between the battery and the power supply starting circuit and a voltage between the power supply starting circuit and the button switch when the button switch is pressed;
A device for preventing malfunction of a push button switch, characterized in that the charge/discharge circuit is configured to determine the time for which the startup current flows when the button switch is pressed by setting a time constant for transitioning from a transient state to a steady state. The device for preventing malfunction of a push button switch according to claim 1, characterized in that the charging and discharging circuit is a circuit in which a resistor and a capacitor are arranged in parallel. the power supply starting circuit is a PNP transistor having a base resistor, the battery is connected to an emitter side, and the charge/discharge circuit is connected to a base side;
3. The device for preventing malfunction of a push button switch according to claim 2, wherein a resistance value of the base resistor is set to be smaller than a resistance value of the resistor constituting the charge/discharge circuit. the power supply starting circuit is an FET having a gate-source resistor, the source side of which is connected to the battery, and the gate side of which is connected to the charge/discharge circuit;
3. The device for preventing malfunction of a push button switch according to claim 2, wherein the resistance value of the gate-source resistor is set to be smaller than the resistance value of the resistor constituting the charge/discharge circuit.

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