JPH08327684A - Led marker lamp system - Google Patents

Abstract

PURPOSE: To obtain an LED marker lamp system in which the connecting conditions of line between an LED marker lamp and a control section can be detected with no possibility of recognizing the sign erroneously. CONSTITUTION: When an FET 8 is turned off, a current flows through circuits 6, 7 and a resistor 9 into a circuit section 10 so long as the circuits 6, 7 are not opened and the phototransistor 11b in a photocoupler 11 is turned on. Since the circuit section 10 limits the voltage between the joints A and B lower than a level required for lighting an LED sign lamp 1, the LED sign lamp 1 is not lighted thus eliminating the possibility of erroneous recognition of sign. If the circuit 6,7 is opened when the FET 8 is turned off, no current flow into the circuit section 10 and the phototransistor 11b is turned off. When the FET 8 is turned on, the circuit section 10 is short-circuited by the FET 8 and the LED marker lamp 1 is lighted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED marker lamp and the LE.
The present invention relates to an LED marker light system including a control unit for controlling light emission of a D marker light, and a line (electrical connection path) between the LED marker lamp system and the controller, and has various meanings in various applications such as railways and roads. It can be used to show the content.

[0002]

2. Description of the Related Art Since an LED marker light system indicates various meanings (for example, an emergency alarm and a traffic signal), it is necessary to operate it reliably. However, the LED indicator lamp is often installed at a position away from the control unit, and
There is a possibility that the line connecting the ED indicator light and the control unit may be broken. In this case, even if the LED indicator lamp is made to emit light, it cannot be made to emit light, and it is not possible to convey a predetermined meaning. Therefore, in order to improve reliability in the LED marker light system, it is required to monitor the connection state of the line and automatically detect disconnection of the line.

By the way, when such a disconnection of a line is detected, if the LED indicator lamp is made to emit light even when it is not time to transmit a predetermined meaning (for example, at the time of alarm), even if the LED indicator light is emitted. Even if the time is short, it may be mistaken for the meaning to be transmitted, which is not preferable.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and there is no risk of misrecognition of a sign, and the L
It is an object of the present invention to provide an LED marker light system capable of detecting disconnection of a line between an ED marker light and a control unit.

[0005]

In order to solve the above-mentioned problems, an LED marker light system according to a first aspect of the present invention has one or more LEDs and first and second connecting portions, and An LED indicator light that emits light from the one or more LEDs only when a voltage of a predetermined level or more is applied between the first and second connection portions, and the first and second connection portions of the LED indicator light. A control unit that is connected via a line (electrical connection path) and controls light emission of the LED indicator lamp,
A control unit having switching means for turning on / off in response to a light emission control signal, wherein the LED indicator lamp and the switching means are connected in series to a DC power source;
A first resistor connected between the first and second connection parts on the side of the ED indicator light and a parallel connection with the switching means on the control part side, and the switching means is turned off. Circuit means for forming a current path and limiting the voltage between the first and second connection parts of the LED indicator lamp to a level lower than the predetermined level when in the state; and a first circuit for the circuit means. And a first current detecting means for detecting whether or not a current of a predetermined level or more is flowing.

An LED indicator light system according to a second aspect of the present invention is the LED indicator light system according to the first aspect, wherein the circuit means is supplied with a current of a second predetermined level or more higher than the first predetermined level. It further comprises second current detecting means for detecting whether or not the current is flowing.

As the first and second current detecting means, the circuit means is indirectly connected to the circuit means by detecting whether or not a voltage higher than a predetermined level is applied to a predetermined portion of the circuit means. It may be one that detects whether or not a current of the first or second predetermined level or more is flowing.

The first and second current detecting means may form part of the circuit means.

[0009]

According to the LED marker lamp system according to the first and second aspects, the LED marker lamp and the switching means of the control unit are connected in series to the DC power source,
A first resistor is connected between the first and second connection parts of the LED indicator light on the side of the indicator light, and the circuit means is connected in parallel with the switching means.

Therefore, when the switching means is in the off state (that is, when the LED indicator light is not intended to emit light), if the line between the LED indicator light and the control unit is not broken, the line is provided. Current flows from the DC power supply via the first resistor and the circuit means. At this time, the circuit means limits the voltage between the first and second connection portions of the LED indicator light to a level lower than the level required to cause the LED indicator light to emit light, so that the LED indicator light emits light. And therefore there is no risk of misidentification of the sign. On the other hand, when the line between the LED indicator lamp and the control unit is disconnected while the switching means is in the off state, no current flows in the circuit means.

Therefore, the current flowing through the circuit means is set to the first predetermined level which is the current detection reference of the first current detection means when the line is not disconnected when the switching means is in the off state. When the switching means is in the off state, a signal indicating whether or not the line is disconnected is obtained by setting the level to be smaller than the level.

By the way, when the switching means is in the ON state (that is, when the LED indicator lamp is about to emit light), both ends of the circuit means are short-circuited by the switching means. If the LED does not work and the line is not broken, a voltage higher than the level necessary for causing the LED indicator light to emit light is applied between the first and second connection parts of the LED indicator light,
The indicator light will illuminate.

The LE according to the first and second aspects
According to the D-mark light system, when the switching means is in the ON state, no current always flows through the circuit means regardless of whether or not the line is disconnected, so it is detected whether or not the line is disconnected. Can not do it. However, in the LED marker light system, the period during which the LED marker light is not normally emitted is much longer than the period during which the LED marker lamp is caused to emit light, so there is no problem in practical use.

As described above, according to the LED marker light system according to the first and second aspects, the disconnection of the line between the LED marker light and the control unit is detected without fear of erroneous recognition of the marker. be able to.

According to the LED marker lamp system of the second aspect, it is possible to detect whether or not a current of a second predetermined level or higher, which is higher than the first predetermined level, flows in the circuit means. Since it is further provided with the current detection means, it is possible to detect not only the disconnection of the line but also the short circuit of the line.

That is, when the line is short-circuited when the switching means is in the OFF state, the voltage applied to the circuit means is higher than that when the line is normal (when the line is neither disconnected nor short-circuited). As a result, the level of the current flowing through the circuit means becomes higher than in the case where the line is normal. Therefore, the second predetermined level serving as the current detection reference of the second current detection means is set to be larger than the level of the current flowing through the circuit means when the line is normal when the switching means is in the off state. At the same time, by setting the level of the current flowing through the circuit means to be smaller than that when the line is short-circuited when the switching means is in the off state, the second current can be set when the switching means is in the off state. The detection means will provide a signal indicating whether or not the line is shorted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An LED marker light system according to an embodiment of the present invention will be described below with reference to FIG. Figure 1
It is a circuit diagram which shows the LED marker light system by a present Example.

The LED marker light system according to this embodiment is
As shown in FIG. 1, an LED indicator lamp 1 and a control unit 2 such as a control panel for controlling the LED indicator lamp 1 to emit light are provided.

The LED indicator lamp 1 includes a plurality of LEDs 3 and 2.
And two connecting portions A and B, and the plurality of LEs are provided only when a voltage of a predetermined level V _ST or more is applied between the connecting portions A and B.
D3 is designed to emit light. As described above, the LED 3 emits light only when the voltage of the predetermined level V _ST or more is applied between the connecting portions A and B, that is, the current does not flow unless the LED 3 is applied with the forward voltage of the predetermined level or more. This is due to the fact that it does not emit light.

In this embodiment, the LED indicator lamp 1 has a structure in which a plurality of LED rows 4 are connected in parallel between the connecting portions A and B. Each of the plurality of LED rows 4 has a plurality of LEDs 3
And the current limiting resistor 5 are connected in series. The anode side of the LED row 4 is connected to the connection portion A, and L
The cathode side of the ED column 4 is connected to the connecting portion B. In this embodiment, since the LED indicator lamp 1 has the plurality of LEDs 3, the display area can be increased, but in the present invention, the LED indicator lamp 1 only needs to have at least one LED. . Further, in this embodiment, the predetermined level V _ST can be arbitrarily set depending on the number of LEDs 3 in each LED row 4.

The control unit 2 has connecting portions C and D, the connecting portions C and A are connected by a line 6, and the connecting portions D and B are connected by a line 7. Although not shown in the drawing, the lines 6 and 7 are electrical connection paths including not only wiring such as cables but also terminals and connectors as necessary.
In addition, the control unit 2 indicates a DC power source (not shown directly in the figure, V _CC in the figure indicates a power source line connected to the positive electrode of the DC power source, and ground in the figure indicates the negative electrode of the DC power source). A connected earth line (zero volt line), a switching FET 8 as switching means for turning on / off in response to a light emission control signal, a circuit (not shown) for generating the light emission control signal, have. The light emission control signal is input to the gate of the FET 8. The switching means is not limited to the FET, and various other switching elements, contacts of relays, and the like can be used.

The LED indicator lamp 1 and the FET 8 are connected in series to the DC power source. That is, in this embodiment, the connection C is connected to the power supply line V _CC , the connection D is connected to the drain of the FET 8, and the source of the FET 8 is connected to the ground line (grounded).
However, instead of connecting like this, for example, FE
By connecting the drain of T8 to the power supply line V _CC , connecting the source of the FET 8 to the connection C, and connecting the connection D to the ground line, the LED indicator lamp 1 and the FET 8 are connected in series to the DC power supply. You may connect.

On the LED indicator lamp 1 side, a resistor 9 is connected between the connecting portions A and B. Further, on the control unit 2 side, a current path is formed when the FET 8 is in the off state, and LE is provided when the FET 8 is in the off state.
The circuit unit 10 for limiting the voltage V _AB between the connection portions A and B of the D indicator light 1 to a level smaller than the predetermined level V _ST is FE
It is connected in parallel with T8 (that is, between the drain and source of the FET8). Further, the circuit unit 10 has a first
Of the photocoupler 11 as a first current detecting means for detecting whether or not a current of a predetermined level I ₁ or more of
It is provided.

In this embodiment, the light emitting diode 11a of the photocoupler 11 as the first current detecting means is also used as a part of the circuit section 10, and the circuit section 10 includes the Zener diode 12 and the light emitting diode 11a. It is composed of a series circuit. The cathode of the Zener diode 12 is connected to the drain of the FET 8, the anode of the Zener diode 12 is connected to the anode of the light emitting diode 11a, and the cathode of the light emitting diode 11a is the FET.
8 sources.

In this embodiment, when the FET 8 is in the off state, the voltage V _D across the circuit section 10 is the breakdown voltage of the Zener diode 12 and the light emitting diode 1.
It is determined by the forward voltage of 1a, and the voltage V _AB between the connection points A and B is
Is the voltage of the power supply line V _CC (for convenience of explanation, this voltage is also V
_{Expressed as CC} . ) From the voltage V _D across the circuit section 10. Therefore, in this embodiment, as the zener diode 12, a zener diode having a breakdown voltage such that V _AB (= V _CC −V _D ) <V _ST is used. For example, along with the voltage V _CC of the power supply line V _CC is + 24V, when the predetermined level V _ST of LED warning lights 1 is + 8V (i.e., connecting portions A, B
When the LED indicator lamp 1 emits light only when the voltage between them becomes +8 V or more), the voltage V _AB between the connection parts A and B is +8.
As the Zener diode 12, the voltage V _D between both ends of the circuit unit 10 is +18 V so that the voltage becomes +6 V which is smaller than V.
A Zener diode having a breakdown voltage such that

The first predetermined level I _{1 serving as} the current detection reference of the photocoupler 11 is the power supply line V _CC → connection C → line 6 → connection A → resistor 9 → when the FET 8 is off. The level is set to be smaller than the level I _{0 of the} current flowing in the path of connection portion B → line 7 → connection portion D → circuit portion 10 (zener diode 12 → light emitting diode 11a) → earth line. That is, when a current flows through the path when the FET 8 is off, the phototransistor 11b of the photocoupler 11 is turned on, and the circuit unit 10
The phototransistor 11b is set to be in an off state when no current flows into the device.

In the present invention, the structure of the circuit section 10 is not limited to the above-mentioned structure. For example, in FIG. 1, the Zener diode 12 may be replaced with a resistor (not shown). In this case, the voltage V _AB between the connection portions A and B when the FET 8 is in the OFF state is determined by the voltage dividing ratio of the resistor used in place of the Zener diode 12 and the resistor 9. It suffices to set V _AB (= V _CC −V _D ) <V _ST by selecting the resistance value.

Further, in the present invention, the first current detecting means is not limited to the photocoupler 9. For example, the light emitting diode 11a of the photocoupler 9 is replaced with a resistor (not shown), and a comparator or the like for determining whether or not the voltage across the resistor is equal to or higher than a predetermined level corresponding to the predetermined level I ₁ is provided. Alternatively, it may be used as the first current detecting means.

Next, the operation of the LED marker lamp system shown in FIG. 1 will be described.

When the FET 8 is in the off state in response to the light emission control signal (that is, when the LED indicator lamp 1 is not intended to emit light), if the lines 6 and 7 are not broken, the power supply line V _CC → connection part C → line 6 → connection part A → resistor 9 → connection part B → line 7 → connection part D → circuit part 10 (zener diode 12 → light emitting diode 11a) → current flows through the path of the earth line, photo The phototransistor 11b of the coupler 11 is turned on. At this time, since the voltage between the connection parts A and B is limited to a level smaller than the predetermined level V _ST by the circuit part 10, the LED indicator lamp 1 (that is, its LED 3) does not emit light, and therefore the indicator signal is not emitted. There is no risk of misunderstanding. On the other hand, if the lines 6 and 7 are disconnected while the FET 8 is off, the path is cut off and no current flows in the circuit section 10, so that the photocoupler 1
The first phototransistor 11b is turned off.

Therefore, when the FET 8 is off, the on state of the phototransistor 11b of the photocoupler 11 indicates that the lines 6 and 7 are not broken, and the off state of the phototransistor 11b of the photocoupler 11 is the line. This indicates that the lines 6 and 7 are broken, and it is possible to detect whether or not the lines 6 and 7 are broken.

On the other hand, in response to the light emission control signal, the FET
When 8 is in the on state (that is, when the LED indicator lamp 1 is about to emit light), both ends of the circuit section 10 are short-circuited by the FET 8, so that the circuit section 10 does not operate and the line 6 , 7 is not broken, the voltage of the power supply line V _CC (for example, +24
V) is applied almost as it is and a voltage higher than the predetermined level V _ST is applied, so that the LED indicator lamp 1 emits light.

When the FET 8 is in the ON state, current does not always flow in the circuit section 10 regardless of whether the lines 6 and 7 are disconnected. Therefore, it is determined whether the lines 6 and 7 are disconnected. Cannot be detected. However, in the LED marker lamp system, the period during which the LED marker lamp 1 does not emit light is much longer than the period during which the LED marker lamp 1 emits light, so that there is no problem in practical use.

Even when the lines 6 and 7 are normal when the FET 8 is on, the photodiode 11b of the photocoupler 11 is turned off, and the off state of the photodiode 11b is simply kept on the lines 6 and 7. It is not preferable to use the detection signal of disconnection. Therefore, for example, a logical sum (OR) of a state in which the light emission control signal turns off the FET 8 and an off state of the photodiode 11b
It is sufficient to add a circuit for taking out the signal and use the output of this circuit as the detection signal of the final disconnection of the lines 6 and 7. Based on this detection signal, a well-known circuit can turn on the display or generate a sound from a buzzer or the like to generate an alarm for disconnection of the lines 6 and 7.

As described above, the LE according to this embodiment
According to the D marker light system, the disconnection of the lines 6 and 7 between the LED marker light 1 and the control unit 2 can be detected without fear of erroneous recognition of the marker.

Next, an LED marker light system according to another embodiment of the present invention will be described with reference to FIG. Figure 2
FIG. 2 is a circuit diagram showing an LED marker light system according to this embodiment.

In FIG. 2, the same or corresponding components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

The LED indicator lamp system shown in FIG. 1 cannot detect the short circuit of the lines 6 and 7 (that is, the short circuit of the connection portions C and D), while the L circuit shown in FIG.
The ED marker light system is configured to detect not only the disconnection of the lines 6 and 7 but also a short circuit.

The LED indicator light system shown in FIG. 2 is different from the LED indicator light system shown in FIG. 1 in that the circuit section 10 is supplied with a current of a _second predetermined level I ₂ or higher, which is higher than the _first predetermined level I ₁ . The resistor 13 and the photocoupler 14 as the second current detecting means for detecting whether or not the current is flowing.
Is added.

In the present embodiment, the resistor 13 as the second current detecting means and the light emitting diode 14a of the photocoupler 14 are also used as a part of the circuit section 10, and the circuit section 10 is a Zener. It is composed of a series circuit of a diode 12, a resistor 13 and a light emitting diode 11a of the photocoupler 11, and a light emitting diode 14a of a photocoupler 14 connected in parallel with the resistor 13. The cathode of the Zener diode 12 is connected to the drain of the FET 8, the anode of the Zener diode 12 is connected to one end of the resistor 13, and the other end of the resistor 13 is connected to the anode of the light emitting diode 11a.
The cathode of 1a is connected to the source of the FET 8, the anode of the light emitting diode 14a is connected to the one end of the resistor 13, and the cathode of the light emitting diode 14a is connected to the other end of the resistor 13. In FIG. 2, the photodiode of the photocoupler 11 and the photodiode of the photocoupler 14 are omitted.

Similar to the LED marker light system shown in FIG. 1, as the Zener diode 12, V _AB (= V _CC -V)
A Zener diode having a breakdown voltage such that _D ) <V _ST is used.

Further, similar to the LED marker lamp system shown in FIG. 1, the first predetermined level I _{1 which} is the current detection reference of the photocoupler 11 is set when the FET 8 is in the off state.
Power line V _CC → Connection C → Line 6 → Connection A → Resistor 9 → Connection B → Line 7 → Connection D → Circuit 10 (Zener diode 12 → Resistor 13 → Light emitting diode 11)
a) → Level I ₀ 'of current flowing in the path of the earth line
It is set smaller.

In the present embodiment, the second predetermined level I _{2 serving as} a current detection reference by the resistor 13 and the photocoupler 14 is set to be higher than the current level I ₀ ′, and the FET 8 is turned off. In the state, the connection portions C and D are short-circuited, and the power supply line V _CC → connection portion C → connection portion D → circuit portion 10 (zener diode 12 → resistor 13
And light emitting diode 14a → light emitting diode 11a) →
Level of current flowing in the path of the earth line I ₀ ″ (>
It is set smaller than I ₀ '). Such a setting causes the phototransistor of the photocoupler 14 to be turned on only when the level of the voltage across the light emitting diode 14a (that is, the voltage drop of the resistor 13) is equal to or higher than a predetermined level. Can be done by setting. Therefore, in this embodiment, specifically, when the current of the level I ₀ ′ flows in the circuit section 10, the phototransistor of the photocoupler 14 does not turn on, and the current of the level I ₀ ″ flows in the circuit section 10. The resistance value of the resistor 13 may be set so that the phototransistor of the photocoupler 14 is turned on when flowing.

Next, the operation of the LED marker lamp system shown in FIG. 2 will be described.

When the FET 8 is in the off state in response to the light emission control signal (that is, when the LED indicator lamp 1 is not made to emit light), the lines 6 and 7 are neither disconnected nor short-circuited and are normal. For example, power line V _CC → connection C → line 6 → connection A → resistor 9 → connection B → line 7 → connection D
→ Circuit part 10 (Zener diode 12 → Resistor 13 →
A current flows through the path of the light emitting diode 11a) to the ground line, and the phototransistor of the photocoupler 11 is turned on. However, the current level thereof is not sufficient to turn on the phototransistor of the photocoupler 14, so the photocoupler 14 The phototransistor remains off. At this time, since the voltage between the connection parts A and B is limited to a level smaller than the predetermined level V _ST by the circuit part 10, the LED indicator lamp 1 (that is, its LED 3) does not emit light, and therefore the indicator signal is not emitted. There is no risk of misunderstanding.

When the FET 8 is off, the lines 6, 7
When the line is disconnected, the path is cut off, no current flows through the circuit section 10, and the phototransistors of the photocoupler 11 and the photocoupler 14 are both turned off.

When the FET 8 is off, the lines 6, 7
Short circuit, power supply line V _CC → connection C → connection D →
Circuit part 10 (Zener diode 12 → resistor 13 and light emitting diode 14a → light emitting diode 11a) → a large current flows through the path of the earth line, and photocoupler 11
Also, both phototransistors of the photocoupler 14 are turned on.

Therefore, when the FET 8 is in the off state, the off state of the phototransistor of the photocoupler 11 indicates the disconnection of the lines 6 and 7, and the on state of the phototransistor of the photocoupler 14 causes the short circuit of the lines 6 and 7. As shown, the disconnection and short circuit of the lines 6 and 7 can be detected.

On the other hand, in response to the light emission control signal, the FET
When 8 is in the on state (that is, when the LED indicator lamp 1 is about to emit light), both ends of the circuit section 10 are short-circuited by the FET 8, so that the circuit section 10 does not operate and the line 6 , 7 is normal, the voltage of the power supply line V _CC (for example, +24 V) is applied almost as it is between the connection parts A and B, and a voltage higher than the predetermined level V _ST is applied, so that the LED indicator lamp 1 emits light.

When the FET 8 is on, current does not always flow in the circuit section 10 regardless of whether the lines 6 and 7 are disconnected or short-circuited, and the phototransistors of the photocoupler 11 and the photocoupler 14 are Since both of them are always off, it is impossible to detect whether the lines 6 and 7 are open or short-circuited. However, in the LED marker lamp system, the period during which the LED marker lamp 1 does not emit light is much longer than the period during which the LED marker lamp 1 emits light, so that there is no problem in practical use.

When the FET 8 is on, the photodiode of the photocoupler 11 is turned off even if the lines 6 and 7 are not broken, and the off state of the photodiode of the photocoupler 11 is simply kept on the line 6 as it is. , 7 is not preferable as the detection signal of disconnection. Therefore, for example, a circuit for taking a logical sum (OR) between the state in which the light emission control signal turns off the FET 8 and the off state of the photodiode of the photocoupler 11 is added, and the output of this circuit is added to the final lines 6, 7 It may be used as a detection signal of disconnection. On the other hand, when the FET 8 is in the ON state, the photodiode of the photocoupler 14 is also always in the OFF state and is not in the ON state. Therefore, the ON state of the photodiode of the photocoupler 14 can be used as it is as a short circuit detection signal of the lines 6 and 7. Good. Based on the detection signal of disconnection or short circuit, a well-known circuit can turn on an indicator or generate a sound from a buzzer or the like to generate an alarm of disconnection or short circuit of the lines 6 and 7.

As described above, the LE according to this embodiment
According to the D marker light system, it is possible to detect not only the disconnection of the lines 6 and 7 between the LED marker light 1 and the control unit 2 but also a short circuit without fear of erroneous recognition of the marker.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

For example, also in FIG. 2, the drain of the FET 8 is connected to the power supply line V _CC , the source of the FET 8 is connected to the connecting portion C, and the connecting portion D is connected to the earth line, whereby the LED indicator lamp 1 and The FET 8 may be connected in series with the DC power supply. Also in this case, the circuit unit 10 is connected in parallel with the FET 8.

Also in FIG. 2, the Zener diode 12 may be replaced with a resistor (not shown). In this case, the voltage V _AB between the connection portions A and B when the FET 8 is in the OFF state is determined by the voltage dividing ratio of the resistor used in place of the Zener diode 12 and the resistor 9. By selecting the resistance value, V _AB (=
It may be set such that V _CC -V _D ) <V _ST .

Further, the second current detecting means is not limited to the structure using the photocoupler 14, either.

[0057]

As described above, according to the present invention,
The connection state of the line between the LED indicator light and the control unit can be detected without the risk of misidentification of the sign.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an LED marker light system according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an LED marker light system according to another embodiment of the present invention.

[Explanation of symbols]

 1 LED indicator light 2 control part 3 LED 6,7 line 8 FET 9 resistor 10 circuit part 11 photocoupler 12 Zener diode 13 resistor 14 photocoupler A, B, C, D connection part

Claims (2)

[Claims] 1. One or more LEDs and first and second connecting portions, and the one or more LEDs only when a voltage of a predetermined level or more is applied between the first and second connecting portions. LE of
D is a LED indicator light and a control unit connected to the first and second connection units of the LED indicator light via a line, and controlling emission of the LED indicator light, and responding to a light emission control signal. And a control unit having switching means for turning on and off, and the LED indicator lamp and the switching means are connected in series to a DC power source, and on the LED indicator lamp side, the first and second A first resistor connected between the connection unit and the switching unit in parallel on the control unit side, and when the switching unit is in an off state,
Circuit means for forming a current path and limiting the voltage between the first and second connection parts of the LED indicator light to a level lower than the predetermined level; and a current for the circuit means of a first predetermined level or higher. An LED marker light system, comprising: a first current detecting unit that detects whether or not the current flows. 2. A second current detecting means for detecting whether or not a current of a second predetermined level or higher, which is higher than the first predetermined level, is flowing through the circuit means. The LED marker light system according to claim 1.