JP7552115B2 - Vehicle electronic circuit and vehicle meter - Google Patents

Description

The present invention relates to a vehicle electronic circuit and a vehicle instrument.

A known example of a conventional vehicle electronic circuit is the configuration disclosed in Patent Document 1. The vehicle electronic circuit (vehicle instrument) shown in Patent Document 1 is a vehicle instrument (A) that detects the operating state of a flasher switch (F). The vehicle instrument (A) has a control means (4) that branches off and connects to a signal line connected to the flasher switch (F), and drives a switch means (3) provided on the ground terminal side of the resistor (1) to perform intermittent control.

JP 2014-118082 A

In a configuration such as vehicle instrument (A), an intermittent current flows to ground via resistor (1) during intermittent energization. The intermittent current flows in a 50 msec cycle for 10 msec per cycle. In this configuration, the current consumption is reduced by reducing the energization time by 80% compared to a configuration that does not use intermittent control, but considering the cycle for the control means (4) to capture the voltage value, there is a limit to how much the energization time can be reduced. In that respect, this configuration still has room for improvement in terms of reducing heat generation. If heat is generated, for example, condensation may occur inside the sealed container that houses the electronic circuit, or current consumption may increase.

Therefore, the object of the present invention is to provide a vehicle electronic circuit and vehicle instrument that reduces heat generation by focusing on the above-mentioned problems.

In order to achieve the above object, the present invention provides an electronic circuit for a vehicle, comprising:
An electronic circuit for a vehicle that operates in response to a switch voltage at a point between a switch that opens and closes a circuit and an input unit to which a voltage of the switch is input,
a leak detection trigger circuit that outputs a leak detection trigger signal;
a voltage detection circuit that switches a transistor in response to the input of the leak detection trigger signal in accordance with the magnitude of the switch voltage;
a leakage path resistor connected in series with the transistor between the point and ground, and through which a current flows from the point to the ground in response to the switching;
Equipped with
In the voltage detection circuit, at least when the switch is off and the leak is not occurring, switching is performed so that no current flows through the leak path resistance, and when the switch is off and the leak is occurring, switching is performed so that current flows through the leak path resistance .

From another perspective, in order to achieve the above object, a vehicle meter according to the present invention comprises:
a control means having an analog input port as the input unit and controlling an electrical component mounted on a vehicle based on the switch voltage;
the vehicle electronic circuit as described above, which operates in response to the switch voltage at the point between the switch and the input ;
an alarm that is controlled by the control means and that notifies information;
Equipped with
the switch voltage varies in response to the switching of the voltage detection circuit of the vehicle electronic circuit and the opening and closing of the switch;
The control means
When the switch voltage is equal to or lower than a first threshold value, the switch is determined to be off, and the electrical component is controlled;
When the switch voltage is equal to or greater than a second threshold value that is greater than the first threshold value, the switch is determined to be on, and the electrical component is controlled;
When the switch voltage fluctuated by the voltage detection circuit is between a first threshold value and a second threshold value, it is determined that the switch is in a leak state, and the alarm is controlled to notify that the switch is in a leak state.

1 is a diagram showing a circuit configuration of a vehicle electronic circuit (a switch input circuit 1) according to a first embodiment; 4 is a time chart showing state transitions of main parts of a circuit when there is no leakage. 4 is a time chart showing state transitions of main parts of a circuit when a leak occurs. 1 is a diagram showing the configuration of a switch input circuit 10 and a vehicle instrument 100.

Hereinafter, the vehicle electronic circuit according to each embodiment will be described in detail with reference to the accompanying drawings.

[First embodiment]
1-1. Description of the configuration 1-2. Description of the behavior 1-3. Example of effect [Modification]
2-1. First modified example 2-2. Other modified examples 2-3. Examples of effects

[First embodiment]
<1-1. Description of the configuration>
1 is a diagram showing an example of a circuit configuration of an electronic circuit for a vehicle according to the present disclosure. One of the preferred application forms of the electronic circuit for a vehicle according to the present disclosure is as a switch input circuit 1 as shown in FIG.

Vehicle V is a vehicle such as an automobile or motorcycle, and is equipped with, for example, a power source and a power transmission system to move a user (a passenger or user) or any loaded cargo. The user operates an operation unit (such as switch 2 described below) to input operation information as an electrical signal to a control means (such as microcomputer 5 described below) of vehicle V. Based on the input operation information, the control means can control and operate the electrical components mounted on vehicle V.

The vehicle V includes a switch input circuit 1, a switch 2, a battery 3 which is an example of a power source, a microcomputer 5 which is an example of a control means and an input unit, a diode 90, a resistor 91, voltage dividing resistors 92 and 93, and a case ground point. The case ground point may be grounded at a point beyond the case ground point, or may be grounded directly.

The switch input circuit 1 is connected between the point between the switch 2 and the input section 6 and the case ground point. The detailed configuration will be described later.

The switch 2 has a switch element 21 and a leak resistance component 22. The switch 2 can be operated by a user (passenger, user) of the vehicle V to electrically open or close the circuit. The switch element 21 can be an element that converts input operated by a person into an electrical signal, such as a push button switch, toggle switch, rocker switch, or tactile switch. The switch 2 is, for example, a two-terminal circuit, with one terminal connected to the battery 3 and the other terminal connected to the input unit 6 or the switch input circuit 1. The voltage difference between the other terminal (the point where the input unit 6, the switch 2, and the switch input circuit 1 are connected to each other) and ground is defined as the switch voltage B.

The switch 2 also has a leak resistance component 22. The leak resistance component 22 is a resistance component that occurs in the switch 2 when a leak occurs due to water leakage or the like, and can be, for example, several hundred Ω, as one example, about 300 Ω. Note that during normal times when no leak occurs, if the switch element 21 is cut off, the switch 2 can electrically cut off the terminals and enter a high impedance state.

The battery 3 is an example of a power source that supplies power to the switch 2. The battery 3 can be any device capable of supplying power, but for example, a lead battery that generates 13 V can be used.

The microcomputer 5 is electrically connected to the electrical components mounted on the vehicle V, and electrically controls the electrical components based on the electrical signals input to the microcomputer 5. The microcomputer 5 is connected to the switch 2 and the switch input circuit 1 via voltage dividing resistors 92 and 93, and controls the behavior of the electrical components based on the switch voltage B applied to the input port 5a. In other words, the microcomputer 5 is also an example of an input section. As described below, the microcomputer 5 also has a trigger port 5b. This constitutes part of the leak detection trigger circuit 15 that the switch input circuit 1 has.

The microcomputer 5 can be, for example, a microcomputer equipped with a memory unit such as ROM or RAM used for storing a specific program and various data, a memory area during calculations, a CPU for performing calculations according to the specific program, and an input/output interface, and can be used as an example of the input unit 6 or the leak detection trigger circuit 15.

Diode 90 is an example of a rectifying element. Diode 90 is connected to protect elements such as transistors that are vulnerable to reverse current caused by various factors (disturbances, etc.). Resistor 91 ensures a certain level of current flow through switch element 21. Diode 90 and switch element 21 can be omitted.

The voltage dividing resistors 92 and 93 are resistors for reducing the magnitude of the switch voltage B to a level that the input section (microcomputer 5, etc.) can withstand. There are no restrictions on the resistance value of the voltage dividing resistors 92 and 93 as long as they can divide the voltage, but if the resistance is too small, the current that flows will increase and power will be wasted, so a large resistance such as 10 kΩ is preferable.

The switch input circuit 1 has a leak path resistor 11, a voltage detection circuit 14, and a leak detection trigger circuit 15.

Leak path resistor 11 is a resistor with one terminal connected to the switch voltage B and the other terminal connected to transistor 12. The current flowing through this resistor is defined as leak path resistor current C. As an example, the resistance value of leak path resistor 11 is 100 Ω.

The voltage detection circuit 14 compares whether the voltage of the switch voltage B is greater than or less than a predetermined threshold value, and if it is smaller, passes a current through the leak path resistor 11. The voltage detection circuit 14 can be composed of, for example, a transistor 12, a resistor 40, a Zener diode 41, a resistor 42, and a transistor 43. Note that the transistor 43 is used for signal inversion and may be omitted. In that case, it is preferable to also invert the signal of the leak detection trigger signal A described below.
The breakdown voltage of the Zener diode 41 is equal to the above-mentioned "predetermined threshold value" to which the switch voltage B is compared, and can be set to, for example, 6 V. In addition, it is desirable that the breakdown voltage be greater than the switch voltage B after a drop during leakage, which will be described later.
The detailed behavior will be described later.

The leak detection trigger circuit 15 is a circuit that outputs a signal that triggers the voltage detection circuit 14 to perform a leak detection operation. The leak detection trigger circuit 15 can be composed of, for example, a trigger port 5b of the microcomputer 5, a resistor 50, and a transistor 51. The resistor 50 prevents an excessive current from flowing to the transistor 51.
The trigger port 5b is an output port for an electric signal, and outputs a leakage detection trigger signal that triggers the voltage detection circuit 14 to perform a leakage detection operation. When the leakage detection trigger signal is turned on, the transistor 51 itself is turned on, and as a result, the leakage detection trigger circuit 15 is turned on. When the leakage detection trigger circuit 15 is turned on, the voltage detection circuit 14 performs a leakage detection operation.

In the example shown, the leak detection trigger circuit 15 switches itself on and off depending on whether the transistor is on or off. However, as shown in a modified example, the leak detection trigger circuit 15 may also switch itself on and off depending on whether the voltage is high or low. In addition, the leak detection trigger signal may be inverted as appropriate.

The leak detection trigger signal A may be any signal that turns on the leak detection trigger circuit 15. The leak detection trigger signal A is, for example, a voltage value, and is, for example, an intermittent signal with a period of 50 msec. The leak detection trigger signal A is on for 50 μsec per period.
That is, the duty ratio of the leak detection trigger signal A is 0.1%, and the on-time is 50 μsec.

Conventional intermittent current methods for vehicle circuits generally set the on-time to about 10 milliseconds or more due to the microcontroller's input time. This was because the input timing of the microcontroller's input port was controlled by intermittent current, and it was difficult to further shorten the time due to the microcontroller's voltage input time.

However, in the vehicle circuit disclosed herein, the on-time of intermittent current flow does not affect the input port itself. As described below, the leak detection trigger signal A disclosed herein only needs to be a signal that triggers the voltage detection circuit to start operating, in other words, a trigger signal that can even induce a transistor response.

Therefore, the leak detection trigger signal A has a duty ratio (on time/cycle) of 1% or less, and more preferably, the leak detection trigger signal has a duty ratio of 0.1% or less. In addition, the leak detection trigger signal A preferably has an on time per cycle between 10 μsec and 500 μsec. In addition, the leak detection trigger signal A has a cycle between 1 msec and 500 msec, and more preferably, the cycle between 1 msec and 100 msec.

<1-2. Explanation of behavior>
The behavior of the switch input circuit 1, which is an example of an electronic circuit for a vehicle, will be described with reference to FIGS.

FIG. 2 shows the state transition of the switch status, the leak detection trigger signal A (Voltage A), the switch voltage B (Voltage B), and the leak path resistor current C (Voltage C) when no leak is occurring (non-leakage).
FIG. 3 shows the state transition of the switch status, the leak detection trigger signal A (Voltage A), the switch voltage B (Voltage B), and the leak path resistance current C (Voltage C) when a leak occurs (with leakage).

In both Figures 2 and 3, the horizontal axis represents time [sec]. The scale has been omitted to improve readability. Each state indicates a state at the same timing at the same horizontal axis position. In other words, by looking vertically in the drawing, the state of each key part at that time can be read.

The switch state is state information that takes two values on the vertical axis.
For other voltage and current states, the vertical axis indicates the voltage or current. Detailed values are indicated by numbers attached to the solid lines of the graphs. Some values have been omitted to improve readability. Detailed values will be indicated in the specification one by one. The dashed lines indicate the threshold values of the switches.

> 1 When there is no leak (Fig. 2)
>1-1 When switch 2 is on First, when switch 2 is on, switch voltage B is always at a potential of about 12.3 V obtained by subtracting the voltage drop (0.7 V) in the diode from the battery voltage (13 V).
When the leak detection trigger signal A is off (0 V), the transistor 51 is turned off and the leak detection trigger circuit 15 is turned off. When the leak detection trigger circuit 15 is in the off state, the voltage detection circuit 14 operates so that no current flows through the leak path resistor 11. Specifically, since the transistor 51 is off, the transistor 43 is turned on, and subsequently the transistor 12 is turned off.

When the leak detection trigger signal A is on (5V), the transistor 51 is on and the leak detection trigger circuit 15 is on. When the leak detection trigger circuit 15 is on, the voltage detection circuit 14 operates so that a current flows through the leak path resistor 11. Specifically, because the transistor 51 is on, the transistor 43 is off, and then the transistor 12 is on. Therefore, while the leak detection trigger signal A is on, the leak path resistor current is calculated by dividing the inter-terminal voltage by its own resistance value, and is therefore 12.3V/100Ω, or 123mA.

Here, the power consumption Pc_normal when there is no leakage and the switch 2 is on is as follows:
Pc_normal = I^2 × R × Duty
=(123mA)^2 × 100Ω × 50μsec/50[msec] =0.0015[W]

This is an almost negligible amount of power for a vehicle electronic circuit. The reason why power consumption during normal operation can be reduced in this way is due to the short generation time of the leak path resistance current C, which is achieved by the circuit configuration of the present disclosure. In the configuration of the present disclosure, as an example, a current flows for only 50 μsec, but it is possible to shorten this even further depending on the response performance of the transistors used. The switching capability of a transistor is generally several μsec, so this can be shortened depending on the number of transistors from the source of the leak detection trigger signal to the leak path resistance.

>1-2 When switch 2 is off When switch 2 is off, switch voltage B becomes 0V, so leakage path resistance current C becomes 0A.

As described above, a vehicle electronic circuit applied as the switch input circuit 1 can significantly reduce the normal power consumption for leak detection.

>2 When there is a leak (Fig. 3)
>2-1 When switch 2 is on First, even during leakage, when switch 2 is on, the conductive switch element 21 and the leakage resistance component 22 are in a parallel state, so that the leakage resistance component 22 can be ignored and each state shows the same transition as when there is no leakage as described above.

>2-2 When switch 2 is off First, at the moment when switch 2 transitions from on to off, no current flows through leak path resistor 11, so switch voltage B maintains approximately 12.3 V. Strictly speaking, although switch element 21 turns off, a leak occurs, so battery voltage is applied through leak resistance component 22, and current flows to voltage dividing resistors 92 and 93. Here, the leak resistance component is generally several hundred Ω, and voltage dividing resistors 92 and 93 have sufficiently large resistance values, so switch voltage B maintains approximately 12.3 V.

Then, the leak detection trigger signal A turns on. This turns on transistor 51, turns off transistor 43, and turns on transistor 12. This forms a current path from battery 3 to leak resistance component 22, leak path resistance 11, transistor 12, and ground. The leak path resistance current C and switch voltage B at this time are as follows:

Leak path resistance current C=(13V-0.7V)/(300Ω+100Ω)=30.75[mA]
Switch voltage B = (30.75mA) x 100Ω = 3.075[V]

Next, when the leak detection trigger signal A changes from 5V to 0V, transistor 51 turns off. However, because the switch voltage B remains low at 3.075V, no current flows through Zener diode 41 and resistor 42, and transistor 43 remains off. And transistor 12 continues to remain on.

Therefore, once the voltage detection circuit 14 detects a low voltage and the transistor 12 turns on, it remains on regardless of the state of the leak detection trigger signal A, and the switch voltage B continues to be held at 3.075V.

When the switch element 21 subsequently starts to conduct electricity, the horizontal axis reverts to the behavior of 0 msec.

The vehicle electronic circuit disclosed herein is configured to output a leak detection trigger signal when the leak detection operation starts, but is also excellent in that the leak detection trigger signal does not cause fluctuations in the switch voltage. This means that even if an indicator using a light source, for example, is applied to the input section, there is no risk of voltage fluctuations causing flicker, making it highly versatile.

<1-3. Example of effects>
The above-mentioned vehicle electronic circuit includes:
A switch input circuit 1 detects occurrence of leakage in a switch 2 based on a switch voltage B at a point between a switch 2 that opens and closes a circuit and an input unit 6 to which a voltage of the switch 2 is input,
a leak detection trigger circuit 15 that outputs a leak detection trigger signal A;
a voltage detection circuit 14 which, when a leak detection trigger signal A is input, compares a switch voltage B with a predetermined voltage and performs switching;
a leakage path resistor that allows a current to flow based on a switching operation of the voltage detection circuit 14 when the voltage detection circuit 14 detects a drop in the switch voltage B;
A switch input signal comprising:

This configuration results in an electronic circuit for a vehicle that can detect the presence or absence of a leak in the switch while consuming low power.

[Modification]
In the above description, an example of a form in which the vehicle electronic circuit is mounted on a vehicle has been described, and some well-known techniques have been omitted from the description of the present disclosure.
In addition, the present invention is not limited to this embodiment, and various improvements and modifications can be made as appropriate without departing from the spirit of the invention. Hereinafter, configurations in which the vehicle electronic circuit of the present invention is modified and applied will be exemplified. In order to reduce overlapping explanations, detailed explanations of components with the same reference numerals may be omitted.

<2-1. First modified example>
The electronic circuit for a vehicle according to the present disclosure may be configured as a switch input circuit 10 as shown in Fig. 4. Also, it may be applied as a vehicle instrument 100 as shown in Fig. 4.

The vehicle instrument 100 is mounted on the vehicle V while connected to the switch 2, and by being equipped with a switch input circuit 10, it is possible to detect the leak state of the switch 2 with little power consumption.

The vehicle instrument 100 includes an alarm (not shown). The alarm is an electrical component that conveys information to the user. The alarm conveys information to the user, for example, by sound, light, or touch. Examples of such an alarm include a speaker or a display. Displays include indicators that use a light source and a translucent colored dial, and various electronic displays (liquid crystal displays and organic electroluminescence displays).

When a control means such as a microcomputer is applied to the input section, the control means and the alarm may be electrically connected to notify, for example, of a leak condition of a switch.

In addition, in this modified example, a configuration such as an LED indicator module is applied as the input unit 6. The input unit 6 has an LED 61 (Light Emitting Diode), a limiting resistor 62, a resistor 63, a capacitor 64, a Zener diode 65, and a limiting resistor 66.

The Zener diode 65 is provided to prevent the LED 61 from erroneously lighting up when the switch voltage B drops during leak detection and transitions to the leak detection voltage, which can be considered an intermediate voltage. With this configuration, it is possible to more reliably reduce malfunctions of the input section (on operation due to erroneously detecting on) when there is a leak and the switch 2 is off.

In this type of input unit 6, its own state (the light emission state of LED 61) changes based on the switch voltage B.

That is, the input unit 6 may be configured to change its own state or control electrical components mounted on the vehicle V based on the state of the switch voltage B. As an example, a configuration in which the switch voltage B is input to the LED 61 and the microcomputer 5 is shown.

Similar to the switch input circuit 1, the switch input circuit 10 may include a leak path resistor, a voltage detection circuit, and a leak detection trigger circuit. In this modification, a modification of the voltage detection circuit and the leak detection trigger circuit is also shown, but it goes without saying that this may also be applied to the switch input circuit 1.

The switch input circuit 10 includes a voltage detection circuit 140 and a leak detection trigger circuit 150.

As in the first embodiment, the voltage detection circuit 140 compares whether the switch voltage B is greater than or less than a predetermined threshold, and performs switching to switch whether or not a current flows through the leak path resistor 11. The voltage detection circuit 140 has a reset IC 8 and a transistor 12.

When the leak detection trigger signal A (voltage value) issued by the leak detection trigger circuit 150 goes high, the reset IC 8 compares whether the switch voltage B is greater than or less than the reference voltage (predetermined threshold value). If the switch voltage B is greater, the reset IC 8 outputs a signal to turn off the transistor 12. If the switch voltage B is smaller, the reset IC 8 outputs a signal to turn on the transistor 12.

The leak detection trigger circuit 150 has a pulse generator 9. The pulse generator 9 outputs a predetermined pulse signal. In other words, it applies a voltage to the voltage detection circuit 140 as a leak detection trigger signal. The applied voltage is preferably an intermittent, periodic signal. The pulse generator 9 may be configured as a digital signal output port of a control means such as a microcomputer 5.

<2-2. Other Modifications>
Although the embodiment shows a configuration in which the input port 5a of the microcomputer 5 is applied, the input port 5a may be an analog input port.
In this case, when the switch voltage B is equal to or lower than the first threshold value, it may be determined that the switch 2 is off, and the microcomputer 5 may control the electrical components.
When the switch voltage B is equal to or greater than a second threshold value that is greater than the first threshold value, it may be determined that the switch 2 is on, and the electrical component may be controlled.
When the switch voltage B is between the first threshold value and the second threshold value, it may be determined that the switch 2 is in a leak state, and the fact that the switch 2 is in a leak state may be notified by controlling an alarm.

As a method for the alarm to notify the user of a leak condition, a method of notifying the user of general malfunction information is also applicable. In this case, the user will recognize that some kind of malfunction has occurred even if they do not know what specific malfunction has occurred, and will be able to take the vehicle to a dealer or other service shop or an automobile repair shop, which will allow specialized staff to identify the malfunction.

<2-3. Example of effects>
The above-mentioned vehicle instrument 100 includes:
a microcomputer 5 having an input port 5a which is an analog input port and controlling electrical components mounted on a vehicle V based on a switch voltage B;
An alarm that is controlled by the microcomputer 5 and that notifies information;
A vehicle instrument 100 comprising:
Microcomputer 5 is
When the switch voltage B is equal to or lower than the first threshold value, it is determined that the switch 2 is off, and the electrical component is controlled.
When the switch voltage B is equal to or greater than a second threshold value that is greater than the first threshold value, it is determined that the switch 2 is on, and the electrical component is controlled;
When the switch voltage B is between a first threshold value and a second threshold value, the vehicle instrument determines that the switch 2 is in a leak state and notifies the user that the switch 2 is in a leak state by controlling an alarm.

V Vehicle A Leak detection trigger signal B Switch voltage C Leak path resistance current

REFERENCE SIGNS LIST 1, 10 Switch input circuit 11 Leak path resistor 14, 140 Voltage detection circuit 12 Transistor 40 Resistor 41 Zener diode 42 Resistor 43 Transistor 15, 150 Leak detection trigger circuit 50 Resistor 51 Transistor

2 switch 21 switch element 22 leak resistor

3 Battery

5. Microcomputer (an example of a control unit)
5a Input port 5b Trigger port

6 Input unit 61 LED
62 Resistor 63 Resistor 64 Capacitor 65 Zener diode 66 Resistor 67 Transistor

8 Reset IC

9 Pulse generating circuit

90 Diode 91 Resistor 92 Voltage dividing resistor 93 Voltage dividing resistor

100 Vehicle Instruments

Claims (6)

An electronic circuit for a vehicle that operates in response to a switch voltage at a point between a switch that opens and closes a circuit and an input unit to which a voltage of the switch is input,
a leak detection trigger circuit that outputs a leak detection trigger signal;
a voltage detection circuit that switches a transistor in response to the input of the leak detection trigger signal in accordance with the magnitude of the switch voltage;
a leakage path resistor connected in series with the transistor between the point and ground, and through which a current flows from the point to the ground in response to the switching;
Equipped with
In the voltage detection circuit, at least when the switch is off and the leak is not occurring, switching is performed so that no current flows through the leak path resistor, and when the switch is off and the leak is occurring, switching is performed so that a current flows through the leak path resistor.
Vehicle electronic circuits. 2. The electronic circuit for a vehicle according to claim 1, wherein the leak detection trigger signal is an intermittent signal. 3. The electronic circuit for a vehicle according to claim 2, wherein the leak detection trigger signal has a duty ratio of 1% or less, and more preferably, the leak detection trigger signal has a duty ratio of 0.1% or less. 3. The electronic circuit for a vehicle according to claim 2, wherein the leak detection trigger signal has an on-time per period between 10 μsec and 500 μsec. 3. The electronic circuit for a vehicle according to claim 2, wherein the leak detection trigger signal has a period between 1 msec and 500 msec, and more preferably has a period between 1 msec and 100 msec. a control means having an analog input port as the input unit and controlling an electrical component mounted on a vehicle based on the switch voltage;
The vehicle electronic circuit according to claim 1 , which operates in response to the switch voltage at the point between the switch and the input section;
an alarm that is controlled by the control means and that notifies information;
Equipped with
the switch voltage varies in response to the switching of the voltage detection circuit of the vehicle electronic circuit and the opening and closing of the switch;
The control means
When the switch voltage is equal to or lower than a first threshold value, the switch is determined to be off, and the electrical component is controlled;
When the switch voltage is equal to or greater than a second threshold value that is greater than the first threshold value, the switch is determined to be on, and the electrical component is controlled;
When the switch voltage fluctuated by the voltage detection circuit is between a first threshold value and a second threshold value, the switch is determined to be in a leak state, and the vehicle instrument notifies the user that the switch is in a leak state by controlling the alarm.

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