JP6119510B2 - LED lighting unit abnormality detection device - Google Patents

Description

  The present invention relates to an abnormality detection device for an LED lighting unit that detects an abnormality of the LED lighting unit such as disconnection of an LED in an LED lighting unit including a light emitting diode (LED).

  In recent years, light-emitting diodes have been used in place of incandescent bulbs as light sources for vehicle lighting devices. Further, as a device for detecting a failure such as an LED disconnection, an LED disconnection detection device has been devised that detects whether or not an LED is disconnected by supplying a pulse signal having a pulse width that does not light the LED to the LED (Patent Document). 1). Thereby, even if it is at the time of the disconnection detection of LED, a disconnection detection can be performed with the light extinguished.

JP 2010-105590 A

  Some LEDs have a light emission state that is recognized by the user even with a minute current, and lighting in an unintended situation due to inflow of current from the disconnection detection circuit is conceivable. As in Patent Document 1, a configuration that detects disconnection of an LED when an operation device such as an ignition switch is switched to a start and stop position is suitable for an LED that is invisible to the user, such as a headlamp. However, meter panel lighting and room lighting may be lit even though the user has not performed an operation for lighting, and the user may feel uncomfortable.

  In addition, since the “pulse signal having a pulse width that does not light the LED” is different for each LED, there is a problem that the control is complicated and the control program changes for each LED.

  With the above problem as a background, the present invention aims to provide an abnormality detection device for an LED lighting unit that can detect an abnormality of the LED lighting unit with a simple configuration without causing the user to feel uncomfortable. To do.

An abnormality detection device for an LED lighting unit for solving the above problems includes an LED lighting unit including a light emitting diode as a light source, a lighting instruction detection unit that detects a lighting instruction of the LED lighting unit, and lighting for lighting the light emitting diode. A lighting current supply unit that supplies current to the LED lighting unit, and an abnormality detection current supply unit that supplies an abnormality detection current for detecting an abnormality of the LED lighting unit, including at least a disconnection of the light emitting diode, to the LED lighting unit; With
When the lighting instruction is detected, before the lighting current supply unit supplies the lighting current, the abnormality detection current supply unit supplies the abnormality detection current for a predetermined first detection time, and within the first detection time, An abnormality detection unit is further provided for detecting whether or not the LED lighting unit is abnormal based on the supply state of the abnormality detection current.

  With the above configuration, since the abnormality determination of the LED lighting unit is performed before the LED lighting unit is turned on, the abnormality of the LED lighting unit can be detected with a simple configuration. Moreover, the timing which supplies an electric current to a LED lighting part can be put together. As a result, the control program is not complicated. Furthermore, even if the LED lighting part is lit by the abnormality detection current, if the first detection time has elapsed, the light is turned on immediately after that based on the lighting instruction, so it will not be lit at a timing not intended by the user, The user does not feel uncomfortable.

The figure which shows the structural example of the abnormality detection apparatus of the LED lighting part of this invention. The flowchart explaining the abnormality detection process at the time of LED lighting. The flowchart explaining the abnormality detection process at the time of LED light extinction. The figure which shows the input / output voltage of a comparator at the time of normal and abnormality of a LED lighting part. The timing chart which shows the state of the signal and electric current in an abnormality detection process.

  Hereinafter, an abnormality detection device (hereinafter, abbreviated as “abnormality detection device”) for an LED lighting unit according to the present invention will be described with reference to the drawings. In FIG. 1, the whole structure of the abnormality detection apparatus 1 is shown. The abnormality detection device 1 is included in, for example, a lighting device and a lighting device inside and outside the vehicle using LEDs. The abnormality detection device 1 includes an ECU (Electronic Control Unit) 10 and an LED module 20 (LED lighting unit of the present invention). The LED module 20 is turned on / off based on a turn-on / off instruction signal input to the input port P1 of the control circuit 11 of the ECU 10. The on / off instruction signal may be any one based on a user's switch operation, one transmitted from another device via a communication network, or one based on a sensor signal.

  The ECU 10 includes a control circuit 11 (lighting instruction detection unit, turn-off instruction detection unit, lighting current supply unit of the present invention), a switching element 12 (switch of the present invention, lighting current supply unit), and a comparison circuit 13 (abnormality detection of the present invention). Part) and an abnormality detection current supply part 14.

  The control circuit 11 is configured as a computer including a known CPU, ROM, RAM (all not shown) and the like. The CPU executes the control program stored in the ROM, thereby controlling the turning on / off of the LED module 20 as described above.

  The on / off instruction signal input to the input port P1 of the control circuit 11 may indicate two states of H level (light on) and L level (light off), or a well-known PWM (Pulse Width Modulation: pulse width modulation). ) Method, and a pulse waveform having a variable duty ratio (that is, LED brightness) may be used. The H level of the pulse waveform is used as a lighting instruction, and the L level is used as a light-off instruction.

  For example, a well-known FET (Field-Effect Transistor) is used as the switching element 12, and based on an instruction from the control circuit 11, a lighting current for lighting the LED of the LED module 20 is supplied / cut off. . A mechanical switch such as a relay may be used.

  The comparison circuit 13 includes a comparator COMP constituted by an operational amplifier or the like and a peripheral circuit (not shown). One input terminal Vin1 of the comparator COMP has a supply voltage (for example, battery voltage + B) to the ECU 10 as an internal resistance of the resistor R1 and a constant current circuit cc1 (for limiting the current to the input terminal Vin1). (Reference voltage Vref: see FIG. 4) is input. The drive voltage (Vd: see FIG. 4) to the LED module 20 is input to the other input terminal Vin2 of the comparator COMP. The drive voltage is obtained by subtracting the voltage drop of the switching element 12 or the abnormality detection current supply unit 14 from the supply voltage to the ECU 10.

  The above-described configuration is as follows: “The lighting current supply unit includes a switch that supplies and cuts off the lighting current, and the abnormality detection unit includes both ends of the switch when the switch is open and the supply of the lighting current is cut off. Based on the voltage comparison, the presence or absence of an abnormality in the LED lighting part is detected. " More specifically, “a predetermined reference voltage is input to one end of the switch, and a driving voltage for driving the LED lighting unit to be lit is input to the other end of the switch”. . With this configuration, it is possible to detect the presence or absence of an abnormality in the LED lighting unit without using a complicated circuit or control.

  The abnormality of the LED module 20 includes disconnection of the LED, disconnection of a current supply path to the LED such as the resistor R2, and the like, and an output terminal 21 for supplying current or applying drive voltage to the LED module 20 of the ECU 10. Means opening.

  The abnormality detection current supply unit 14 includes a constant current circuit cc2 and a switch SW2. Based on the instruction of the control circuit 11, the switch SW2 is opened and closed, and an abnormality detection current for detecting an abnormality of the LED of the LED module 20 is supplied / cut off. The abnormality detection current is preferably a value lower than the current value necessary for lighting the LED.

  The LED module 20 includes, in addition to one or more LEDs (light emitting diodes) and a current limiting resistor R2, a circuit (driver circuit or the like) necessary for lighting the LEDs.

  The abnormality detection process at the time of LED lighting included in the control program executed in the control circuit 11 will be described with reference to FIG. First, it is determined whether or not a lighting instruction signal is input to the input port P1.

  When the lighting instruction signal is input (S11: Yes), abnormality detection is started (S12). That is, the switch SW2 of the abnormality detection current supply unit 14 is closed, and the abnormality detection current is supplied to the LED module 20. Further, a timer for waiting until a predetermined stable time elapses is started.

  As shown in FIG. 1, the power line (+ B) to the switching element 12 to the output terminal 21 (lighting current supply path) or the power line (+ B) to the abnormality detection current supply unit 14 to the output terminal 21 (abnormality detection current path). There is a stray capacitance C between and ground. Since charges are stored in the stray capacitance C for a while after the supply of the abnormality detection current is started, no abnormality detection current is supplied to the LED module 20. Therefore, the time until charge accumulation in the stray capacitance C is completed is defined as a stable time. The stabilization time can be estimated from the circuit configuration.

  The configuration of the above-described step S12 is as follows: “The abnormality detection unit detects the presence or absence of an abnormality in the LED lighting unit after a predetermined stabilization time has elapsed since the abnormality detection current supply unit started supplying the abnormality detection current. To do. With this configuration, it is possible to detect whether the LED module 20 is abnormal without being affected by the stray capacitance C.

  Further, depending on the circuit configuration, it may not be necessary to consider the stabilization time. At this time, the timer is not started in step S12, and step S13 is not executed.

  When the stable time has elapsed (S13: Yes), a timer for generating an abnormality detection time (first detection time of the present invention) is started (S14). Next, the state of the output terminal Vout of the comparator COMP of the comparison circuit 13 is acquired (S15). When the output terminal Vout is at the L level (see FIG. 4), that is, when the abnormality of the LED module 20 is not detected (S16: No), it is checked whether or not the abnormality detection time has elapsed. The abnormality detection time is set to be equal to or longer than the time required to determine whether the LED module 20 is abnormal at least once.

  When the abnormality detection time has not elapsed (S17: No), the process returns to step S15 to determine again whether there is an abnormality. On the other hand, when the abnormality detection time has elapsed (S17: Yes), it is determined that the LED module 20 is normal (S18). Thereafter, the switching element 12 is closed, and a lighting current is supplied to the LED module 20 to light the LED (S19). At this time, a lighting current and an abnormality detection current are supplied to the LED module 20.

  On the other hand, when the output terminal Vout is at the H level (see FIG. 4) (S16: Yes), it is determined that the LED module 20 is abnormal (S20). At this time, the switching element 12 remains open, and no lighting current is supplied to the LED module 20 (S21). Next, the switch SW2 of the abnormality detection current supply unit 14 is opened to cut off the supply of the abnormality detection current to the LED module 20 (S22). At this time, the timer is stopped.

  Next, the process at the time of LED abnormality is performed (S23). For example, a signal indicating an abnormality of the LED module 20 is output from an output port (which may be a communication port) P2 of the control circuit 11 to the outside. When a display device is connected to the ECU 10, a message indicating that an abnormality has occurred in the LED module 20 is displayed on the display device.

  The configuration of steps S16 to S21 described above is “the lighting current supply unit determines whether or not to supply the lighting current to the LED lighting unit based on the result of the abnormality detection in the first detection time”. With this configuration, when an abnormality is detected in the LED lighting section, no lighting current is supplied to the LED lighting section, so that useless power consumption can be suppressed and an increase in the abnormality of the LED lighting section can be prevented.

  It is good also as a structure which does not set abnormality detection time by the above-mentioned structure. In this case, the abnormality detection is executed only once, and steps S14 and S17 are not executed. Further, the abnormality detection may be performed a plurality of times, and the determination may be made by majority detection state (normal / abnormal). Further, normality / abnormality may be determined by performing abnormality detection a plurality of times and determining whether or not the same state has continued a predetermined number of times.

With reference to FIG. 3, the abnormality detection process when the LED is turned off, which is included in the control program executed in the control circuit 11, will be described. The configuration of FIG. 3 is to supply an LED lighting unit including a light emitting diode as a light source, a turn-off instruction detecting unit for detecting a turn-off instruction of the LED lighting unit, and a lighting current for turning on the light-emitting diode to the LED lighting unit. A lighting current supply unit, and an abnormality detection current supply unit that supplies the LED lighting unit with an abnormality detection current for detecting an abnormality of the LED lighting unit, including at least a disconnection of the light emitting diode,
When the lighting current supply unit supplies the lighting current, when an extinction instruction is detected, after the lighting current supply unit stops supplying the lighting current, the abnormality detection current supply is performed for a predetermined second detection time. The unit further supplies an abnormality detection current and further includes an abnormality detection unit that detects the presence or absence of an abnormality in the LED lighting unit based on the supply state of the abnormality detection current within the second detection time.

  With the above configuration, since the abnormality determination of the LED lighting unit is performed after the LED lighting unit is turned off, the abnormality of the LED lighting unit can be detected with a simple configuration. Moreover, the timing which supplies an electric current to a LED lighting part can be put together. As a result, the control program is not complicated. Furthermore, even if the LED lighting part is turned on by the abnormality detection current, it is turned off when the second detection time elapses, so that it does not turn on at a timing unintended by the user, and the user does not feel uncomfortable. In addition, although there is a restriction that the abnormality detection cannot be performed unless the LED lighting part is turned off, there is an advantage that it is less affected by the stray capacitance C than the configuration in which the abnormality detection is performed when the LED lighting part is turned on.

  First, it is determined whether a turn-off instruction signal is input to the input port P1. At this time, the LED module 20 is supplied with a lighting current and an abnormality detection current. When the turn-off instruction signal is input (S31: Yes), the switching element 12 is opened, the lighting current supply to the LED module 20 is cut off, and the LED is turned off (S32). At this time, only the abnormality detection current is supplied to the LED module 20. Next, abnormality detection is started (S33). That is, a timer for generating an abnormality detection time (second detection time of the present invention) is started.

  Next, the state of the output terminal Vout of the comparator COMP of the comparison circuit 13 is acquired (S34). When the output terminal Vout is at the L level (see FIG. 4), that is, when the abnormality of the LED is not detected (S35: No), it is checked whether or not the abnormality detection time has elapsed.

  When the abnormality detection time has not elapsed (S36: No), the process returns to step S34, and the presence / absence of abnormality is determined again. On the other hand, when the abnormality detection time has elapsed (S36: Yes), the LED module 20 is determined to be normal (S37). Thereafter, the switch SW2 of the abnormality detection current supply unit 14 is opened to interrupt the supply of the abnormality detection current to the LED module 20 (S38).

  On the other hand, when the output terminal Vout is at the H level (see FIG. 4) (S35: Yes), it is determined that the LED module 20 is abnormal (S39). At this time, the timer is stopped. Next, the process at the time of LED abnormality similar to step S23 of FIG. 2 is executed (S40). Thereafter, the switch SW2 of the abnormality detection current supply unit 14 is opened to interrupt the supply of the abnormality detection current to the LED module 20 (S38).

  It is good also as a structure which does not set abnormality detection time by the above-mentioned structure. In this case, the abnormality detection is executed only once. In step S33, the timer is not started and step S36 is not executed.

  2 and FIG. 3 are combined, “the LED lighting unit including a light emitting diode as a light source, the lighting instruction detection unit that detects a lighting instruction of the LED lighting unit, and the light-off instruction detection that detects a light-off instruction of the LED lighting unit. LED, a lighting current supply unit for supplying a lighting current for lighting the light emitting diode to the LED lighting unit, and an abnormality detection current for detecting an abnormality of the LED lighting unit, including at least a disconnection of the light emitting diode, An abnormality detection current supply unit for supplying to the lighting unit, and when the lighting instruction is detected, the abnormality detection current supply unit for a predetermined first detection time before the lighting current supply unit supplies the lighting current. Supplies an abnormality detection current, and when the lighting current supply unit supplies a lighting current, when a turn-off instruction is detected, after the lighting current supply unit stops supplying the lighting current, During the first detection time, the abnormality detection current supply unit supplies the abnormality detection current, and within the first detection time and the second detection time, based on the supply state of each abnormality detection current, the LED lighting unit It further includes an abnormality detection unit that detects the presence or absence of an abnormality.

  With the above configuration, since the abnormality determination of the LED lighting unit is performed before and after the lighting of the LED lighting unit, the abnormality of the LED lighting unit can be detected with a simple configuration. Moreover, the timing which supplies an electric current to a LED lighting part can be put together. As a result, the control program is not complicated. Furthermore, even if the LED lighting part is turned on by the abnormality detection current, it is turned on when the first detection time elapses and is turned off when the second detection time elapses. Therefore, the user does not feel uncomfortable.

  2 and 3, the configuration in which the abnormality detection of the LED module 20 is repeated within the first detection time or the second detection time is “the abnormality detection unit is within the first detection time or the second detection time. When the detection of the presence or absence of abnormality of the LED lighting part is repeated and no abnormality is detected within the first detection time or the second detection time, it is determined that the LED lighting part is normal. With this configuration, it is possible to more accurately detect the presence or absence of an abnormality in the LED lighting part.

  FIG. 4 shows the state of the input / output voltage in the comparator COMP of the comparison circuit 13 when the LED module 20 is normal / abnormal. Note that when the abnormality is detected, the switching element 12 is in an open state. Regardless of the state of the LED module 20, the above-described reference voltage Vref is input to the input terminal Vin1 of the comparator COMP. Further, when the LED module 20 is normal, the drive voltage Vd described above is input to the input terminal Vin2 of the comparator COMP. On the other hand, when the LED module 20 is abnormal, the input terminal Vin <b> 2 is in a so-called “floating” state, and a voltage substantially the same as the power supply voltage (+ B) is input.

  Thus, Vref and peripheral circuit constants are adjusted from the output terminal Vout of the comparator COMP so that an L level is output when the LED module 20 is normal and an H level is output when the LED module 20 is abnormal. . For example, the reference voltage Vref is set to substantially the same value as the drive voltage Vd.

  FIG. 5 shows signal and current states in the abnormality detection processing of FIGS. 2 and 3. When a lighting instruction is input to the input port P1 (indicated as “LED control” in FIG. 5) of the control circuit 11, the switch SW2 is closed and supply of the abnormality detection current from the abnormality detection current supply unit 14 is started. Thereafter, when the time T11 (stable time) elapses, the abnormality of the LED module 20 can be detected. When the stabilization time is not set, an abnormality can be detected immediately when a lighting instruction is input.

  When a time T12 (first detection time) has elapsed since the abnormality of the LED module 20 can be detected, the switching element 12 is closed and the supply of the lighting current is started. Supply of the abnormality detection current from the abnormality detection current supply unit 14 continues. Abnormality detection is not performed while the lighting current is being supplied.

  When a turn-off instruction is input to the input port P1 of the control circuit 11, the switching element 12 is opened to cut off the supply of the lighting current. At this time, the abnormality of the LED module 20 can be detected. Thereafter, when the time T2 (second detection time) elapses, the switch SW2 is opened to cut off the supply of the abnormality detection current from the abnormality detection current supply unit 14.

The current (LED current) flowing through the LED from the turning on to the turning off of the LED is as follows.
・ Before lighting instructions: Zero.
-Until the time T11 + T12 elapses after the lighting instruction is given: I1 (abnormality detection current).
-After time T11 + T12 has elapsed since the lighting instruction was given: I2 (abnormality detection current + lighting current).
-From the time when the turn-off instruction is given until time T2 elapses: I1 (abnormality detection current).
・ After time T2 has elapsed since the instruction to turn off: Zero.

  As shown in FIG. 5, when a lighting current is supplied to the LED module 20, an abnormality detection current may be supplied. This configuration is “the abnormality detection current supply unit supplies the abnormality detection current when the lighting current supply unit supplies the lighting current”. Since the abnormality detection current is a value that does not light the LED, it does not affect the luminance of the LED. Also, the control of supply / cutoff of the abnormality detection current can be simplified. Further, in the configuration in which the supply of the abnormality detection current is started after the lighting current is interrupted, the above-described stray capacitance C is affected, but in this configuration, the stray capacitance C is not affected.

  There is also a method in which the abnormality detection current is not supplied when the LED is on, but is supplied when a turn-off instruction signal is input. However, when the supply of the abnormality detection current is started after the supply of the lighting current is interrupted, there is a possibility that a period in which no current is supplied occurs. Further, when the supply of the lighting current is interrupted after the supply of the abnormality detection current is started, a period in which two currents are supplied may occur. Therefore, there is a possibility that the brightness of the LED changes and the user feels uncomfortable. On the other hand, in the above-described configuration of the present invention, since the lighting current and the abnormality detection current are supplied while the LED is lit, at least the LED can be prevented from instantaneously becoming bright or disappearing.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

1 LED lighting unit abnormality detection device (abnormality detection device)
P1 input port (lighting instruction detection unit, extinguishing instruction detection unit)
10 ECU
11 Control circuit (lighting instruction detection unit, turn-off instruction detection unit, lighting current supply unit)
12 Switching element (switch, lighting current supply part)
13 Comparison circuit (abnormality detection unit)
COMP comparator (abnormality detection unit)
14 Anomaly detection current supply section SW2 switch cc2 constant current circuit 20 LED module (LED lighting section)
21 Output terminal LED Light emitting diode

Claims (7)

An LED lighting unit including a light emitting diode as a light source;
A lighting instruction detection unit for detecting a lighting instruction of the LED lighting unit;
A lighting current supply unit for supplying a lighting current for lighting the light emitting diode to the LED lighting unit;
An abnormality detection current supply unit that supplies an abnormality detection current for detecting an abnormality of the LED lighting unit, including at least a disconnection of the light emitting diode, to the LED lighting unit;
With
When the lighting instruction is detected, before the lighting current supply unit supplies the lighting current, the abnormality detection current supply unit supplies the abnormality detection current for a predetermined first detection time,
An abnormality detection device for an LED lighting unit, further comprising an abnormality detection unit that detects the presence or absence of an abnormality in the LED lighting unit based on a supply state of the abnormality detection current within the first detection time. An LED lighting unit including a light emitting diode as a light source;
A lighting instruction detection unit for detecting a lighting instruction of the LED lighting unit;
A turn-off instruction detection unit that detects a turn-off instruction of the LED lighting unit;
A lighting current supply unit for supplying a lighting current for lighting the light emitting diode to the LED lighting unit;
An abnormality detection current supply unit that supplies an abnormality detection current for detecting an abnormality of the LED lighting unit, including at least a disconnection of the light emitting diode, to the LED lighting unit;
With
When the lighting instruction is detected, before the lighting current supply unit supplies the lighting current, the abnormality detection current supply unit supplies the abnormality detection current for a predetermined first detection time,
In addition, when the lighting current supply unit supplies the lighting current, when the turn-off instruction is detected, the second current detection is performed after the lighting current supply unit stops supplying the lighting current. For the time only, the abnormality detection current supply unit supplies the abnormality detection current,
The LED further comprising an abnormality detection unit that detects the presence or absence of an abnormality of the LED lighting unit based on a supply state of each abnormality detection current within the first detection time and the second detection time. An abnormality detection device for lighting parts. The LED lighting unit according to claim 1 or 2 , wherein the lighting current supply unit determines whether to supply the lighting current to the LED lighting unit based on a result of abnormality detection in the first detection time. Anomaly detection device. The abnormality detecting unit, from the start of supply of the abnormality detecting current supply unit is the abnormality detecting current, after the lapse of a stable predetermined time, claims 1 to detect the presence or absence of abnormality of the LED lighting unit 4. The abnormality detection device for an LED lighting unit according to any one of 3 above. The abnormality detection device for an LED lighting unit according to any one of claims 1 to 4 , wherein the abnormality detection current supply unit supplies the abnormality detection current when the lighting current supply unit supplies the lighting current. . The lighting current supply unit includes a switch for supplying and blocking the lighting current,
The abnormality detection unit detects whether or not the LED lighting unit is abnormal based on a comparison of voltages at both ends of the switch when the switch is in an open state and the supply of the lighting current is interrupted. The abnormality detection apparatus of the LED lighting part of any one of thru | or 5 . The LED lighting according to claim 6 , wherein a predetermined reference voltage is input to one end of the switch, and a driving voltage for lighting the LED lighting unit is input to the other end of the switch. Part abnormality detection device.

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