JP3631087B2 - Electronic switch with push switch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic switch that operates a push switch to switch a switching element such as a transistor or FET on and off.
[0002]
[Prior art]
FIG. 1 shows an electronic switch that operates a push switch to switch a switching element on and off. This electronic switch has a feature that contact failure can be reduced as compared with a slide switch that slides a contact to switch on and off. In addition, there is a feature that the structure of the push switch can be simplified compared to the slide switch.
[0003]
In the electronic switch shown in FIG. 1, the push switch 2 is connected to the input terminal 11 of the flip-flop circuit 1, and the output terminal 12 of the flip-flop circuit 1 is connected to the switching element 3. When the rising voltage is input to the input terminal 11, the flip-flop circuit 1 switches the output between “H” and “L” and inverts the output. The push switch 2 inputs a rising voltage to the flip-flop circuit 1 when pressed. The switching element 3 is turned on when “H” is input from the flip-flop circuit 1 and turned off when “L” is input. Therefore, each time the push switch 2 is pressed, the electronic switch shown in this figure alternately inverts the output of the flip-flop circuit 1 to “H” and “L” and switches the switching element 3 on and off.
[0004]
[Problems to be solved by the invention]
The electronic switch of FIG. 1 turns on and off the load current with the switching element 3, so that the contact failure of the switching element 3 can be eliminated. However, when the push switch 2 chatters, the switching element 3 also chatters for a short time. There is a disadvantage of switching on and off. Chattering of the switching element can be prevented, for example, by connecting a Schmitt trigger circuit or the like to the input side of the flip-flop circuit, or connecting a timer circuit that ignores the input for a certain period. However, this structure has a drawback that the circuit is complicated and expensive.
[0005]
The present invention has been developed for the purpose of solving such drawbacks. An important object of the present invention is to provide an electronic switch including a push switch that can prevent chattering of a switching element even if the push switch causes chattering.
[0006]
[Means for Solving the Problems]
An electronic switch including the push switch according to the present invention includes a push switch 2, a flip-flop circuit 1 that connects the push switch 2 to an input terminal 11, and a switching element 3 that is controlled to be turned on and off by the output of the flip-flop circuit 1. Is provided. Further, in the electronic switch, the flip-flop circuit 1 detects the rising voltage input from the push switch 2, inverts the output, and switches the switching element 3 on and off with the output of the flip-flop circuit 1.
[0007]
Further, the electronic switch is characterized by having all the following configurations. (A) The input terminal 11 of the flip-flop circuit 1 is connected to the negative side of the power supply via the second voltage dividing resistor R2, and via the push switch 2 and the first voltage dividing resistor R1 connected in series with each other. Connected to the positive side of the power supply.
(B) The first voltage dividing resistor R1 is larger than the second voltage dividing resistor R2, and the resistance ratio between the first voltage dividing resistor R1 and the second voltage dividing resistor R2 is such that the voltage input to the input terminal 11 is low level. It is set to be lower than the threshold value.
(C) The first voltage dividing resistor R1 connects the first voltage dividing capacitor C1 in parallel.
(D) The second voltage dividing resistor R2 connects the second voltage dividing capacitor C2 in parallel.
(E) The first voltage dividing capacitor C1 is larger than the capacitance of the second voltage dividing capacitor C2.
(F) The flip-flop circuit 1 has a control terminal 14.
(G) The flip-flop circuit 1 switches the output to “H” when a rising voltage is input to the input terminal 11 when the control terminal 14 is set to “H”, and to the input terminal 11 when the control terminal 14 is “L”. When the rising voltage is input, the output is switched to “L”.
(H) The control terminal 14 is connected to the negative side of the power supply via the integrating capacitor C3 and to the inverting output terminal 13 via the integrating resistor R3.
[0008]
Furthermore, in the electronic switch including the push switch of the present invention, it is preferable that the resistance value of the first voltage dividing resistor R1 is 10 times or more the resistance value of the second voltage dividing resistor R2.
[0009]
Furthermore, in the electronic switch including the push switch of the present invention, it is preferable that the capacitance of the first voltage dividing capacitor C1 is 10 times or more than the capacitance of the second voltage dividing capacitor C2.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies an electronic switch for embodying the technical idea of the present invention, and the present invention does not specify the electronic switch as follows.
[0011]
Further, in this specification, in order to facilitate understanding of the scope of claims, the numbers corresponding to the members shown in the examples are referred to as “the scope of claims” and “the means for solving the problems”. It is added to the member shown by. However, the members shown in the claims are not limited to the members in the embodiments.
[0012]
FIG. 2 shows a circuit diagram of an electric razor with an electronic switch. Although this figure shows a circuit diagram of an electric razor, the electronic switch of the present invention does not specify the use as an electric razor. The electric razor shown in the figure switches the motor 4 on and off with an electronic switch. The motor 4 is connected to the battery 5 via the switching element 3 of the electronic switch. The battery 5 is a secondary battery such as a nickel-hydrogen battery, a nickel-cadmium battery, or a lithium ion secondary battery, or a dry battery that cannot be charged.
[0013]
The electronic switch includes a push switch 2, a flip-flop circuit 1 that connects the push switch 2 to an input terminal 11, a switching element 3 that is controlled to be turned on / off by the output of the flip-flop circuit 1, and the flip-flop circuit 1. And a reset circuit 6 for resetting.
[0014]
The push switch 2 is a switch that turns on when pressed and returns to off when released. Unlike the slide switch, this switch is not held in the on position and the off position, and is turned on only when pressed. Since the push switch 2 is connected to the positive side of the power supply via the first voltage dividing resistor R1, when this is pushed and turned on, the rising voltage is input to the input terminal 11 of the flip-flop circuit 1.
[0015]
The flip-flop circuit 1 includes an input terminal 11 connected to the push switch 2, an output terminal 12 connected to the switching element 3, an inverting output terminal 13 that outputs a signal inverted with respect to the output terminal 12, and an inverting output A control terminal 14 connected to the terminal 13 via an integration resistor R3, a reset terminal 15 for inputting a reset signal, a power supply terminal 16 connected to the positive side of the power source, and a negative terminal connected to the negative side of the power source 17.
[0016]
The operation of the flip-flop circuit 1 is shown in the table of FIG. As shown in this table, the flip-flop circuit 1 switches the output terminal 12 from “L” to “H” when a rising voltage is input to the input terminal 11 while the control terminal 14 is set to “H”. . In addition, when a rising voltage is input to the input terminal 11 while the control terminal 14 is set to “L”, the output terminal 12 is switched from “H” to “L”. Since the flip-flop circuit 1 detects the rising voltage input to the input terminal 11 and inverts the output, as shown in the table, the output is not inverted when the voltage at the input terminal 11 decreases.
[0017]
When a reset signal is input to the reset terminal 15, the flip-flop circuit 1 forcibly resets the output terminal 12 to “L” regardless of the signals at the control terminal 14 and the input terminal 11.
[0018]
The switching element 3 is switched on and off by the output of the flip-flop circuit 1. In the illustrated electronic switch, a transistor is used as the switching element 3, and the base of the transistor is connected to the output terminal 12 of the flip-flop circuit 1. An FET can also be used as the switching element. The FET switching element has a gate connected to the output terminal of the flip-flop circuit.
[0019]
The switching element 3 is turned on when “H” is input to the base and the gate, and is turned off when “L” is input. The electric razor shown in the figure turns on the switching element 3 to rotate the motor 4 and turns it off to stop the rotation of the motor 4. Therefore, the switching element 3 is connected in series between the motor 4 and the battery 5.
[0020]
In the flip-flop circuit 1, the input terminal 11 is connected to the negative side of the power supply via the second voltage dividing resistor R2. Further, the input terminal 11 is connected to the positive side of the power supply via the push switch 2 and the first voltage dividing resistor R1 connected in series. The first voltage dividing resistor R1 and the second voltage dividing resistor R2 divide the power supply voltage and input it to the input terminal 11.
[0021]
FIG. 4 shows the voltage at each terminal of the flip-flop circuit 1. As shown in this figure, the resistance divided voltage divided by the first voltage dividing resistor R1 and the second voltage dividing resistor R2 is input to the input terminal 11 of the flip-flop circuit 1. However, the voltage of the input terminal 11 becomes the resistance divided voltage after the push switch 2 is pressed and a sufficient time has elapsed. The voltage at the input terminal 11 at the moment when the push switch 2 is pressed is determined by the ratio of the capacitances of the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2.
[0022]
In order to sufficiently reduce the resistance voltage dividing voltage, the first voltage dividing resistor R1 is made larger than the second voltage dividing resistor R2. This is because the resistance divided voltage is specified by the product of the power supply voltage and R2 / (R1 + R2). Therefore, the resistance divided voltage is specified by the resistance ratio of the first voltage dividing resistor R1 and the second voltage dividing resistor R2. The resistance divided voltage is sufficiently lower than the low level threshold voltage of the input terminal 11, for example, 70% or less, preferably 60% or less, and optimally about 50% of the low level threshold voltage. As described above, the voltage dividing ratio between the first voltage dividing resistor R1 and the second voltage dividing resistor R2 is specified. For example, the resistance value of the first voltage dividing resistor R1 can be increased to about 10 times that of the second voltage dividing resistor R2, so that the resistance divided voltage can be sufficiently lower than the low level threshold value.
[0023]
When the resistance divided voltage is sufficiently lower than the low level threshold voltage, the switching element 3 chatters even when the push switch 2 chatters and the voltage at the input terminal 11 fluctuates when the push switch 2 is released. There is nothing. This is because the voltage at the input terminal 11 changes at a voltage lower than the low level threshold, and the inversion of the flip-flop circuit 1 is prevented by ignoring the rising voltage. Therefore, even if this circuit chatters when the push switch 2 is released, the flip-flop circuit 1 is not inverted, and the switching element 3 does not chatter.
[0024]
However, if the resistance divided voltage is lower than the low level threshold value, the flip-flop circuit 1 cannot be inverted with a voltage that is divided and input by the resistor when the push switch 2 is pressed. In order to invert the flip-flop circuit 1 by inputting a voltage higher than the low level threshold to the input terminal 11, a first voltage dividing capacitor C1 is connected in parallel to the first voltage dividing resistor R1, and the second A second voltage dividing capacitor C2 is connected in parallel to the voltage dividing resistor R2. In order to increase the peak voltage input to the input terminal 11 at the moment when the push switch 2 is pushed, the capacitance of the first voltage dividing capacitor C1 is made larger than the capacitance of the second voltage dividing capacitor C2. Yes.
[0025]
The second voltage dividing resistor R2 that reduces the capacitance is charged at the moment when the push switch 2 is pressed and is increased to the peak voltage of the input terminal 11. The peak voltage input to the input terminal 11 at the moment when the push switch 2 is pressed becomes substantially equal to the product of the power supply voltage and C2 / (C1 + C2). The capacitances of the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 are determined so that the peak voltage is sufficiently higher than the low level threshold value. For example, the capacitance of the first voltage dividing capacitor C1 can be made 10 times the capacitance of the second voltage dividing capacitor C2, and the peak voltage can be made sufficiently higher than the low level threshold. .
[0026]
Further, the flip-flop circuit 1 has an integration capacitor C3 and an integration resistor R3 connected to the control terminal 14 in order to prevent chattering that occurs at the moment the push switch 2 is pressed. The integrating capacitor C3 is connected between the control terminal 14 and the ground which is the negative side of the power source, and the integrating resistor R3 is connected between the control terminal 14 and the inverting output terminal 13.
[0027]
The waveform of the control terminal 14 connecting the integrating capacitor C3 and the integrating resistor R3 is shown in FIG. As shown in this figure, the voltage of the control terminal 14 does not change to “H” and “L” at the moment when the push switch 2 is pressed, but changes slowly with a delay. The delay time in which the voltage at the control terminal 14 changes with a delay is increased by increasing the capacitance of the integrating capacitor C3 and increasing the resistance value of the integrating resistor R3. The flip-flop circuit 1 cannot switch the output terminal 12 from “H” to “L” until the voltage at the control terminal 14 becomes lower than the low level threshold, and the voltage at the control terminal 14 is at the high level. The output terminal 12 cannot be switched from “L” to “H” until it becomes higher than the threshold value.
[0028]
Therefore, a cancel period from when the push switch 2 is pressed until the voltage at the control terminal 14 decreases below the low level threshold or rises above the high level threshold is input from the push switch 2. A signal input to the terminal 11 is ignored. The cancellation period is determined so that chattering that occurs at the moment the push switch 2 is pressed can be effectively prevented.
[0029]
In the above electronic switch, when the push switch 2 is pressed once, the switching element 3 is turned on and the motor 4 is started. When the push switch 2 is pressed again, the switching element 3 is turned off and the motor 4 is rotated. Every time the push switch 2 is pressed, the switching element 3 is switched on and off, and the motor 4 repeats rotation and stop.
[0030]
This electronic switch operates as follows.
(1) When the battery 5 is connected to the circuit, the reset circuit 6 power-on resets the flip-flop circuit 1. In this state, the flip-flop circuit 1 has the output terminal 12 at “L”, the inverted output terminal 13 at “H”, and the control terminal 14 at “L”. Since the output terminal 12 is “L”, the switching element 3 is turned off.
[0031]
(2) When the push switch 2 is turned on in this state, a rising voltage is applied to the input terminal 11 of the flip-flop circuit 1. This rising voltage triggers the flip-flop circuit 1 to set the output terminal 12 to “H”, and this “H” signal switches the switching element 3 on. The ON switching element 3 energizes the load current to rotate the motor 4. At this time, the inverting output terminal 13 becomes “L” and the control terminal 14 becomes “H”.
[0032]
(3) Next, when the push switch 2 is turned on again, the rising voltage is inputted to the input terminal 11 of the flip-flop circuit 1. The rising voltage triggers the flip-flop circuit 1 to switch the output terminal 12 from “H” to “L”. The “L” signal at the output terminal 12 turns off the switching element 3 and stops the rotation of the motor 4.
[0033]
The operations of (2), (3), (2), (3)... Are repeated, and the output of the flip-flop circuit 1 is alternately switched between “H” and “L”, and the switching element 3 is turned on / off. The motor 4 repeats operation and stop by being switched.
[0034]
When the battery voltage decreases while the motor 4 is operating, the reset circuit 6 inputs a reset signal to the reset terminal 15 of the flip-flop circuit 1. With this signal, the flip-flop circuit 1 is reset, the output terminal 12 is switched to “L”, the switching element 3 is turned off, and the operation of the motor 4 is stopped.
[0035]
When the push switch 2 chatters, chattering of the switching element 3 is prevented by the following operation.
[0036]
(1) The control terminal 14 of the flip-flop circuit 1 for preventing malfunction due to chattering at the moment when the push switch 2 is pressed receives a signal from the inverting output terminal 13, but is connected to the integration resistor R3 and the integration capacitor C3. As shown in FIG. 3, the waveform input to the control terminal 14 rises slowly or falls slowly. In the flip-flop circuit 1, the input signal at the input terminal 11 is canceled until the voltage at the control terminal 14 drops to the low level threshold or rises to the high level threshold. For this reason, even if the push switch 2 causes chattering until the voltage at the control terminal 14 falls to the low level threshold or rises to the high level threshold, the flip-flop circuit 1 outputs The switching element 3 is not switched on and off. For this reason, the switching element 3 does not chatter.
[0037]
(2) Preventing malfunction due to chattering at the moment when the push switch 2 is released When the push switch 2 is pressed, the capacitance of the first voltage dividing capacitor C1 is larger than the capacitance of the second voltage dividing capacitor C2. The 2 voltage divider capacitor C2 is charged earlier than the first voltage divider capacitor C1. For this reason, almost the power supply voltage is applied to the input terminal 11 of the flip-flop circuit 1 at the moment when the push switch 2 is pressed. Thereafter, as the first voltage dividing capacitor C1 is charged, the voltage at the input terminal 11 of the flip-flop circuit 1 gradually decreases. When the first voltage dividing capacitor C1 is fully charged, the voltage at the input terminal 11 is Then, the voltage drops to a resistance divided voltage which is the product of the power supply voltage and R2 / (R1 + R2). Since the resistance divided voltage is lower than the low level threshold value, even if the push switch 2 chatters during this time, the voltage of the input terminal 11 does not become higher than the low level threshold value. Chattering of the push switch 2 is ignored.
[0038]
【The invention's effect】
The electronic switch of the present invention has an advantage that chattering of the switching element can be prevented even if the push switch causes chattering. This is because the electronic switch of the present invention has an input terminal of the flip-flop circuit connected to the negative side of the power source via the second voltage dividing resistor, and a push switch connected in series with the positive side of the power source via the first voltage dividing resistor. Are connected to the first voltage dividing resistor in parallel with the first voltage dividing capacitor, the second voltage dividing resistor is connected to the second voltage dividing capacitor in parallel, and the control terminal of the flip-flop circuit is connected to the integrating capacitor. This is because the circuit has a unique circuit configuration that is connected to the inverting output terminal via an integral resistor on the negative side of the power supply.
[0039]
Even when the push switch chatters and the input terminal voltage fluctuates when the push switch is released, this electronic switch changes the input terminal voltage at a low voltage. Circuit inversion is prevented. Further, in this electronic switch, as shown in FIG. 4, the voltage at the control terminal does not change suddenly at the moment when the push switch is pressed, but changes slowly with a delay. For this reason, when the push switch is pressed, the output terminal is not switched even if the push switch chatters. Therefore, the electronic switch of the present invention can reliably prevent chattering of the switching element even if the push switch causes chattering.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a conventional electronic switch. FIG. 2 is a circuit diagram of an electronic switch including a push switch according to an embodiment of the present invention. FIG. 3 is a table showing an operation of a flip-flop circuit. Timing chart showing the voltage at each terminal [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Flip-flop circuit 2 ... Push switch 3 ... Switching element 4 ... Motor 5 ... Battery 6 ... Reset circuit 11 ... Input terminal 12 ... Output terminal 13 ... Inverted output terminal 14 ... Control terminal 15 ... Reset terminal 16 ... Power supply terminal 17 ... -Terminal R1 ... first voltage dividing resistor R2 ... second voltage dividing resistor R3 ... integration resistor C1 ... first voltage dividing capacitor C2 ... second voltage dividing capacitor C3 ... integration capacitor

Claims (3)

Push switch (2), flip-flop circuit (1) connecting this push switch (2) to input terminal (11), and switching element (3) controlled to be turned on and off by the output of flip-flop circuit (1) )
The flip-flop circuit (1) detects the rising voltage input from the push switch (2), inverts the output, and switches the switching element (3) on and off with the output of the flip-flop circuit (1). An electronic switch comprising a push switch characterized by having all the following configurations.
(A) The input terminal (11) of the flip-flop circuit (1) is connected to the negative side of the power supply through the second voltage dividing resistor (R2), and the push switch (2) and the second switch connected in series with each other. It is connected to the + side of the power supply via a 1-voltage divider resistor (R1).
(B) The first voltage dividing resistor (R1) is larger than the second voltage dividing resistor (R2), and the resistance ratio between the first voltage dividing resistor (R1) and the second voltage dividing resistor (R2) is the input terminal (11 ) Is set to be lower than the low level threshold.
(C) The first voltage dividing resistor (R1) connects the first voltage dividing capacitor (C1) in parallel.
(D) The second voltage dividing resistor (R2) connects the second voltage dividing capacitor (C2) in parallel.
(E) The first voltage dividing capacitor (C1) is larger than the capacitance of the second voltage dividing capacitor (C2).
(F) The flip-flop circuit (1) has a control terminal (14).
(G) The flip-flop circuit (1) switches the output to “H” when the rising voltage is input to the input terminal (11) when the control terminal (14) is set to “H”, and the “L” When the rising voltage is input to the input terminal (11), the output is switched to “L”.
(H) The control terminal (14) is connected to the negative side of the power supply via the integration capacitor (C3) and to the inverting output terminal (13) via the integration resistor (R3). The electronic switch comprising a push switch according to claim 1, wherein the resistance value of the first voltage dividing resistor (R1) is 10 times or more the resistance value of the second voltage dividing resistor (R2). The electronic switch comprising a push switch according to claim 1, wherein the capacitance of the first voltage dividing capacitor (C1) is 10 times or more the capacitance of the second voltage dividing capacitor (C2).

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