WO2018198284A1 - Semiconductor light source lighting device and vehicle lamp - Google Patents

Semiconductor light source lighting device and vehicle lamp Download PDF

Info

Publication number
WO2018198284A1
WO2018198284A1 PCT/JP2017/016804 JP2017016804W WO2018198284A1 WO 2018198284 A1 WO2018198284 A1 WO 2018198284A1 JP 2017016804 W JP2017016804 W JP 2017016804W WO 2018198284 A1 WO2018198284 A1 WO 2018198284A1
Authority
WO
WIPO (PCT)
Prior art keywords
output
converter
current
semiconductor light
output voltage
Prior art date
Application number
PCT/JP2017/016804
Other languages
French (fr)
Japanese (ja)
Inventor
祥治 加藤
Original Assignee
三菱電機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to PCT/JP2017/016804 priority Critical patent/WO2018198284A1/en
Publication of WO2018198284A1 publication Critical patent/WO2018198284A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/20—Responsive to malfunctions or to light source life; for protection
    • H05B47/26—Circuit arrangements for protecting against earth faults
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q11/00—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/382—Switched mode power supply [SMPS] with galvanic isolation between input and output
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10—Controlling the light source
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

  • the present invention relates to a semiconductor light source lighting device and a vehicle lamp for lighting a semiconductor light source.
  • LEDs Light Emitting Diodes
  • DRL Daytime Running Lights
  • Headlamps are often lit by connecting multiple LEDs in series to ensure illuminance.
  • the DRL requires a small amount of illuminance, a method of diffusing light emitted from one LED by a light guide may be employed.
  • the voltage required for lighting per LED is about 2V to 4V, but the lighting device is often required to output a voltage up to about 60V in order to turn on both the headlamp and the DRL.
  • the lighting device converts the in-vehicle battery voltage into the LED driving voltage by using a step-up / down DC / DC (Direct Current / Direct Current) converter in order to light the LED. That is, the lighting device includes a step-up / step-down DC / DC converter having a power supply capability larger than the rated power of a semiconductor light source such as an LED.
  • the LED is lit by a constant current output from the step-up / step-down DC / DC converter.
  • the lighting device includes a current measurement circuit that measures the output current of the step-up / step-down DC / DC converter, a current control circuit that performs feedback control of the output current of the step-up / step-down DC / DC converter using the measurement result, Is provided.
  • a current measurement circuit that measures the output current of the step-up / step-down DC / DC converter
  • a current control circuit that performs feedback control of the output current of the step-up / step-down DC / DC converter using the measurement result, Is provided.
  • a plurality of circuit configurations are conceivable as the current measuring circuit, but there is a circuit configuration using an inverting amplifier circuit that accurately measures with a small number of parts.
  • the current measuring circuit is disposed between the ground and the secondary side of the insulated buck-boost DC / DC converter. The output current flowing on the secondary side is measured (see, for example, Patent Document 1).
  • the current measuring circuit is 2
  • the current control circuit measures the current flowing through the secondary side and performs feedback control. When the short-circuit failure occurs, the output load becomes small, and the amount of operation of the current control circuit becomes too large for the output load, so that the output voltage tends to oscillate.
  • the present invention has been made to solve the above-described problems, and an object thereof is to determine a short-circuit failure in which an output voltage oscillates.
  • a semiconductor light source lighting device includes a DC / DC converter that converts an input voltage into an output voltage and supplies the output voltage to one or more semiconductor light sources, an output voltage measurement unit that measures an output voltage of the DC / DC converter, An output current measuring unit that is arranged between the ground connected to the low potential side of the secondary side of the DC / DC converter and the low potential side and measures the output current flowing to the secondary side, and measurement of the output current measuring unit An output current control unit for controlling the output current of the DC / DC converter to be a driving current for lighting one or more semiconductor light sources based on the value, a high potential side on the secondary side of the DC / DC converter, and one A short determination unit that determines a short-circuit failure with a semiconductor light source connected to the highest potential side of the semiconductor light sources.
  • the short determination unit lights one or more semiconductor light sources with a drive current.
  • the Each of the first threshold voltage lower than the output voltage of the DC / DC converter and the second threshold voltage lower than the first threshold voltage, and the measured value of the output voltage measuring unit is the first When the voltage drops below the threshold voltage, it is determined that a short-circuit failure may have occurred, and a current change instruction is issued to the output current control unit. Based on the current change instruction, the output current of the DC / DC converter is When the measured value of the output voltage measurement unit falls below the second threshold voltage in the changed state, it is determined that a short circuit fault has occurred, and the output current control unit receives a current change instruction from the short determination unit. In this case, the output current of the DC / DC converter is controlled to be a test current lower than the drive current.
  • the output current of the DC / DC converter is converted to the drive current. If the measured value of the output voltage measurement unit drops below the second threshold voltage when the output current of the DC / DC converter is changed based on the current change instruction, the short circuit fault occurs. Therefore, it is possible to determine a short-circuit failure in which the output voltage oscillates.
  • FIG. 1 is a circuit diagram showing a configuration example of a semiconductor light source lighting device 10 according to Embodiment 1 of the present invention.
  • the battery 1, the LED 2, and the semiconductor light source lighting device 10 constitute a DRL vehicle lamp.
  • the battery 1 is a power source that supplies an input voltage to the semiconductor light source lighting device 10.
  • the LED 2 is a semiconductor light source used as a DRL.
  • the semiconductor light source is not limited to the LED, and may be a laser diode or the like.
  • the semiconductor light source lighting device 10 mainly includes a step-up / step-down DC / DC converter 11, an output voltage measurement unit 17, an output current measurement unit 18, an output current control unit 19, and a short determination unit 20.
  • a step-up / step-down DC / DC converter 11 an output voltage measurement unit 17, an output current measurement unit 18, an output current control unit 19, and a short determination unit 20.
  • the rectifier circuit, the smoothing circuit, and the like are not shown.
  • the step-up / step-down DC / DC converter 11 converts the input voltage supplied from the battery 1 into an output voltage supplied to the LED 2.
  • the step-up / step-down DC / DC converter 11 is, for example, a flyback type step-up / step-down DC / DC converter using an insulating transformer. Note that the step-up / step-down DC / DC converter 11 is not limited to the flyback type step-up / step-down DC / DC converter, and can convert the input voltage supplied from the battery 1 to a voltage lower or higher. I just need it. Therefore, the semiconductor light source lighting device 10 is used for the purpose of lighting one LED 2 for DRL in the configuration example of FIG. 1, but instead of one LED 2 for DRL, it is connected in series for a headlamp. It is also possible to turn on a plurality of connected LEDs 2.
  • the high potential side input terminal 12 is a terminal for connecting the high potential side of the primary winding of the step-up / step-down DC / DC converter 11 to the high potential side of the battery 1.
  • the low potential side input terminal 13 is a terminal for connecting the low potential side of the primary winding of the step-up / step-down DC / DC converter 11 and the low potential side of the battery 1.
  • a switching element 21 is connected between the low potential side input terminal 13 of the primary winding of the step-up / step-down DC / DC converter 11.
  • the high potential side output terminal 14 is a terminal for connecting the high potential side of the secondary winding of the step-up / step-down DC / DC converter 11 and the anode of the LED 2.
  • the low potential side output terminal 15 is a terminal for connecting the low potential side of the secondary winding of the step-up / step-down DC / DC converter 11 and the cathode of the LED 2.
  • the low potential side of the secondary winding of the step-up / step-down DC / DC converter 11 is connected to the ground 16.
  • the output voltage measurement unit 17 is connected to both ends of the secondary winding of the step-up / step-down DC / DC converter 11, measures the output voltage of the step-up / step-down DC / DC converter 11, and outputs the measured value to the short determination unit 20.
  • the output voltage measuring unit 17 is, for example, a voltage dividing circuit using a resistor or the like, and the output voltage of the step-up / step-down DC / DC converter 11 is converted to a voltage that the short determination unit 20 can perform A / D (Analog / Digital) conversion on. Convert.
  • the output current measuring unit 18 is disposed between the low potential side of the secondary winding of the step-up / step-down DC / DC converter 11 and the ground 16 and measures the output current of the step-up / step-down DC / DC converter 11 to control the output current.
  • the output current measuring unit 18 is, for example, a circuit combining a shunt resistor and an inverting amplifier, and converts the current flowing through the shunt resistor into a voltage that can be A / D converted by the output current control unit 19.
  • the output current control unit 19 controls the output current of the step-up / step-down DC / DC converter 11 based on the measurement value of the output current measurement unit 18.
  • the output current control unit 19 determines the operation amount so that the measured value of the output current measurement unit 18 and the target current value are equal by feedback control, and the duty ratio according to the determined operation amount.
  • the switching element 21 is driven on and off.
  • the short determination unit 20 determines a short failure of the LED 2 based on the measurement value of the output voltage measurement unit 17. When the position 22 indicated by “x” is grounded on the signal line connecting the high potential side output terminal 14 and the LED 2, the short determination unit 20 determines this ground fault as a short fault. When a plurality of LEDs 2 are connected in series between the high-potential side output terminal 14 and the low-potential side output terminal 15, the short determination unit 20 is the highest potential side output terminal of these LEDs 2. A ground fault between the LED 2 arranged on the 14 side and the high potential side output terminal 14 is determined as a short circuit failure.
  • FIG. 2 is a graph showing output voltages at the time of normal lighting and a short circuit failure in the semiconductor light source lighting device 10 according to the first embodiment of the present invention.
  • the horizontal axis of the graph is time, and the vertical axis is the output voltage of the step-up / step-down DC / DC converter 11 measured by the output voltage measuring unit 17 for each sampling period.
  • the output voltage measured by the output voltage measuring unit 17 is stable during normal lighting when no short failure has occurred. On the other hand, when a short circuit failure occurs, the output voltage measured by the output voltage measuring unit 17 oscillates.
  • the short determination unit 20 determines a short failure in two stages using two types of thresholds for determining a short failure.
  • FIG. 3 is a flowchart showing an operation example of the semiconductor light source lighting device 10 according to the first embodiment of the present invention.
  • the semiconductor light source lighting device 10 repeatedly performs the operation shown in the flowchart of FIG. Steps ST1 to ST8 are first stage short circuit failure determinations, and steps ST9 to ST12 are second stage short circuit failure determinations.
  • the short determination unit 20 compares the output voltage measured by the output voltage measurement unit 17 with the latest sampling cycle with a predetermined first threshold voltage.
  • the first threshold voltage is: The voltage is lower than the drive voltage at the smallest number of lighting.
  • the output voltage becomes less than the first threshold voltage, a short circuit failure of the LED 2 is suspected.
  • the short determination unit 20 is not determined as a short failure at this time.
  • step ST1 “NO” When the output voltage measured by the output voltage measurement unit 17 is equal to or higher than the first threshold voltage (step ST1 “NO”), the short determination unit 20 proceeds to step ST2. If the output voltage measured by the output voltage measurement unit 17 is less than the first threshold voltage (step ST1 “YES”), the short determination unit 20 proceeds to step ST3.
  • step ST2 the short determination unit 20 determines that no short failure has occurred. Therefore, the output current control unit 19 performs constant current control of the step-up / step-down DC / DC converter 11 so as to continue the normal lighting of the LED 2.
  • step ST3 the short determination unit 20 starts a built-in timer (not shown).
  • step ST4 when the time measured by the timer is less than the predetermined time (step ST4 “NO”), the short determination unit 20 proceeds to step ST5, and when the time measured by the timer has passed the predetermined time (step ST4). “YES”), go to step ST7.
  • step ST5 the short determination unit 20 compares the output voltage measured by the output voltage measurement unit 17 with the latest sampling period and the first threshold voltage. When the output voltage measured by the output voltage measurement unit 17 is less than the first threshold voltage (step ST5 “YES”), the short determination unit 20 proceeds to step ST6, and the output voltage measured by the output voltage measurement unit 17 is When the voltage is equal to or higher than the first threshold voltage (step ST5 “NO”), the process returns to step ST4.
  • step ST6 the short determination unit 20 counts the number of determinations in which the output voltage is determined to be less than the first threshold voltage in step ST5, and returns to step ST4.
  • step ST7 when the number of determinations in the predetermined time is less than or equal to the predetermined number of times (step ST7 “NO”), the cause that the output voltage has become less than the first threshold voltage is not a short circuit failure but noise or the like. It is determined that the output voltage measuring unit 17 is malfunctioning due to the disturbance of, and the process proceeds to step ST8. On the other hand, if the number of determinations in the predetermined time is larger than the predetermined number (step ST7 “YES”), the short determination unit 20 proceeds to step ST9 to determine the second stage because a short failure is suspected.
  • step ST8 the short determination unit 20 resets the number of determinations, and proceeds to step ST2.
  • step ST9 the short determination unit 20 instructs the output current control unit 19 to set the output current of the step-up / step-down DC / DC converter 11 to the inspection current.
  • the output current control unit 19 changes the output current of the step-up / step-down DC / DC converter 11 to a test current.
  • the output current control unit 19 may change the output current of the step-up / step-down DC / DC converter 11 to the inspection current by setting the target current value of the feedback control to the inspection current, or the duty ratio for driving the switching element 21 on and off. May be changed to a test current by changing the output current of the step-up / step-down DC / DC converter 11 to a value corresponding to the test current.
  • FIG. 4 is a graph showing the output voltage during normal operation and in the supply of the inspection current at the time of short-circuit in the semiconductor light source lighting device 10 according to the first embodiment of the present invention.
  • the horizontal axis of the graph is time, and the vertical axis is the output voltage of the step-up / step-down DC / DC converter 11 measured by the output voltage measuring unit 17 for each sampling period.
  • step ST10 the short determination unit 20 compares the output voltage measured by the output voltage measurement unit 17 with the latest sampling cycle with a predetermined second threshold voltage.
  • the short determination unit 20 proceeds to step ST11, and the output voltage measured by the output voltage measurement unit 17 is When the voltage is less than the second threshold voltage (step ST10 “YES”), the process proceeds to step ST12.
  • step ST11 the short determination unit 20 determines that no short failure has occurred, and instructs the output current control unit 19 to return the inspection current to the drive current during normal lighting.
  • the output current control unit 19 receives this instruction from the short determination unit 20, the output current control unit 19 changes the output current of the step-up / step-down DC / DC converter 11 from the inspection current to the drive current during normal lighting.
  • step ST12 the short determination unit 20 determines that the LED 2 has a short circuit failure. Since the output voltage during energization of the inspection current at the time of the short fault shown in FIG. 4 is more stable than the output voltage during energization of the drive current at the time of the short fault shown in FIG. 2, two steps using the second threshold voltage are used. The time required for the eye determination can be shorter than the time required for the first stage determination using the first threshold voltage. In the flowchart of FIG. 3, the time required for the second stage determination (step ST10) using the second threshold voltage is one sampling period in which the output voltage measurement unit 17 measures the output voltage.
  • the determination method based on time is exemplified as the first step determination using the first threshold voltage.
  • the determination method is not limited to this method, and the determination based on the ratio may be performed.
  • the short determination unit 20 starts counting the number of sampling times of the output voltage. Thereafter, when the number of times of sampling reaches a predetermined number, the short determination unit 20 suspects a short failure when the ratio of the number of determinations counted in step ST6 to the number of times of sampling is larger than the predetermined ratio in step ST7. Proceed to
  • FIG. 5A and 5B are diagrams showing hardware configuration examples of the output current control unit 19 and the short determination unit 20 according to Embodiment 1 of the present invention.
  • Each function of the output current control unit 19 and the short determination unit 20 is realized by a processing circuit. That is, the semiconductor light source lighting device 10 includes a processing circuit for realizing the above functions.
  • the processing circuit may be the processing circuit 100 as dedicated hardware, or may be the processor 101 that executes a program stored in the memory 102.
  • the processing circuit 100 when the processing circuit 100 is dedicated hardware, the processing circuit 100 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or the like. ), FPGA (Field Programmable Gate Array), or a combination thereof.
  • the functions of the output current control unit 19 and the short determination unit 20 may be realized by a plurality of processing circuits 100, or the functions of each unit may be realized by a single processing circuit 100.
  • each function of the output current control unit 19 and the short determination unit 20 is realized by software, firmware, or a combination of software and firmware.
  • Software or firmware is described as a program and stored in the memory 102.
  • the processor 101 reads out and executes a program stored in the memory 102, thereby realizing the function of each unit. That is, the semiconductor light source lighting device 10 includes a memory 102 for storing a program that, when executed by the processor 101, results in the steps shown in the flowchart of FIG. Further, it can be said that this program causes a computer to execute the procedure or method of the output current control unit 19 and the short determination unit 20.
  • the processor 101 is a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like.
  • the memory 102 may be a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), or a flash memory, or a hard disk or a flexible disk.
  • the magnetic disk may be an optical disk such as a CD (Compact Disc) or a DVD (Digital Versatile Disc).
  • the memory 102 also stores information such as the first threshold voltage, the second threshold voltage, and the inspection current.
  • the processing circuit in the semiconductor light source lighting device 10 can realize the above-described functions by hardware, software, firmware, or a combination thereof.
  • the semiconductor light source lighting device 10 includes the step-up / step-down DC / DC converter 11 that converts the input voltage into the output voltage and supplies the output voltage to one or more LEDs 2, and the step-up / step-down DC / DC converter.
  • An output voltage measuring unit 17 that measures the output voltage of the step-up / step-down DC / DC converter 11 and an output current measuring unit 18 that is arranged between the secondary side of the step-up / step-down DC / DC converter 11 and the ground 16 and measures the output current flowing to the secondary side.
  • An output current control unit 19 for controlling the output current of the step-up / step-down DC / DC converter 11 to be a drive current for lighting one or more LEDs 2 based on the measurement value of the output current measuring unit 18;
  • a short determination unit 20 that determines a short circuit failure between the secondary high potential side of the DC converter 11 and the LED 2 connected to the highest potential side of the one or more LEDs 2.
  • the short determination unit 20 has each value of the first threshold voltage and the second threshold voltage, and a short failure occurs when the measurement value of the output voltage measurement unit 17 falls below the first threshold voltage.
  • the output current control unit 19 is instructed to change the test current and the output current of the step-up / step-down DC / DC converter 11 is changed based on the test current change instruction.
  • the output current control unit 19 controls the output current of the step-up / step-down DC / DC converter 11 to be an inspection current lower than the drive current.
  • the inspection current is 1 ⁇ 2 or less of the drive current, even when the output load of the step-up / step-down DC / DC converter 11 is reduced due to a short circuit failure, oscillation is suppressed and stable.
  • the output voltage can be supplied. Therefore, it is possible to more reliably determine a short circuit failure by comparing the stable output voltage with the second threshold voltage.
  • the measured value of the output voltage measuring unit 17 is greater than the first threshold voltage from the time required to determine that the measured value of the output voltage measuring unit 17 has dropped below the second threshold voltage. Since the time required to determine that the voltage has dropped is set longer, the influence of noise and the like can be eliminated when comparing the oscillating output voltage with the first threshold voltage, and a short-circuit failure can be determined more reliably. Can do.
  • the vehicle lamp according to the first embodiment includes a semiconductor light source lighting device 10 including one LED 2 and a step-up / step-down DC / DC converter 11 having a power supply capability that is twice or more the rated power of the single LED 2. Consists of.
  • the semiconductor light source lighting device 10 needs to include a step-up / step-down DC / DC converter 11 having a large power supply capability. If the power supply capability of the step-up / step-down DC / DC converter 11 is large, as described above, if a short circuit failure occurs when the DRL is lit, the output voltage oscillates and the normal output voltage and the peak value of the oscillated output voltage are close to each other. Therefore, it is difficult to distinguish between normal lighting and a short circuit failure. Even in such a case, the short failure can be reliably determined by the short determination method of the short determination unit 20.
  • any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.
  • the semiconductor light source lighting device is suitable for use in a lighting device for a vehicle lamp having a light source for DRL since it determines a short-circuit failure in which output power oscillates.
  • 1 battery 2 LED, 10 semiconductor light source lighting device, 11 buck-boost DC / DC converter, 12 high potential side input terminal, 13 low potential side input terminal, 14 high potential side output terminal, 15 low potential side output terminal, 16 ground , 17 output voltage measurement unit, 18 output current measurement unit, 19 output current control unit, 20 short determination unit, 21 switching element, 22 short fault location, 100 processing circuit, 101 processor, 102 memory.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

When the measurement value of an output voltage measurement unit (17) drops below a first threshold value voltage, a short circuit determination unit (20) determines that there is a possibility of a short circuit failure occurring, and sends an inspection current change command to an output current control unit (19). The output current control unit (19) controls so that the output current of a step-up/step-down DC/DC converter (11) is at an inspection current lower than a drive current. The short circuit determination unit (20) then confirms that a short circuit failure is occurring when the measurement value of the output voltage measurement unit (17) drops below a second threshold value voltage.

Description

半導体光源点灯装置および車両灯具Semiconductor light source lighting device and vehicle lamp
　この発明は、半導体光源を点灯させる半導体光源点灯装置および車両灯具に関するものである。 The present invention relates to a semiconductor light source lighting device and a vehicle lamp for lighting a semiconductor light source.
　近年、車載用ヘッドランプ光源として、ハロゲンランプに代わりＬＥＤ（Ｌｉｇｈｔ　Ｅｍｉｔｔｉｎｇ　Ｄｉｏｄｅ）等の半導体光源を採用する車両が増えている。
　ＬＥＤを用いたヘッドランプは、前照灯のように夜間走行時の運転者の視界確保を目的とした使われ方だけでなく、ＤＲＬ（Ｄａｙｔｉｍｅ　Ｒｕｎｎｉｎｇ　Ｌｉｇｈｔｓ）のように、対向車の運転者に自車両を視認させやすくすることを目的とした使われ方をする場合もある。 In recent years, an increasing number of vehicles employ semiconductor light sources such as LEDs (Light Emitting Diodes) instead of halogen lamps as in-vehicle headlamp light sources.
Headlamps using LEDs are not only used for the purpose of ensuring the visibility of the driver when driving at night like a headlamp, but also for oncoming drivers like DRL (Daytime Running Lights). There are also cases where it is used for the purpose of making the host vehicle easier to see.
　前照灯は、照度を確保するために、複数のＬＥＤを直列に接続して点灯させる場合が多い。これに対し、ＤＲＬは、必要な照度が小さいため、１個のＬＥＤが発する光をライトガイドによって拡散させる方式が採用される場合がある。 前 Headlamps are often lit by connecting multiple LEDs in series to ensure illuminance. On the other hand, since the DRL requires a small amount of illuminance, a method of diffusing light emitted from one LED by a light guide may be employed.
　ＬＥＤ１個当たりの点灯に必要な電圧は２Ｖ～４Ｖ程度であるが、点灯装置としては、前照灯とＤＲＬのどちらも点灯するために６０Ｖ程度まで電圧を出力するよう要求されることが多い。また、点灯装置は、ＬＥＤを点灯させるために、昇降圧ＤＣ／ＤＣ（Ｄｉｒｅｃｔ　Ｃｕｒｒｅｎｔ／Ｄｉｒｅｃｔ　Ｃｕｒｒｅｎｔ）コンバータを用いて車載バッテリ電圧をＬＥＤ駆動電圧に変換することが多い。すなわち、点灯装置は、ＬＥＤ等の半導体光源の定格電力よりも大きな電力供給能力を有する昇降圧ＤＣ／ＤＣコンバータを有している。 The voltage required for lighting per LED is about 2V to 4V, but the lighting device is often required to output a voltage up to about 60V in order to turn on both the headlamp and the DRL. Further, in many cases, the lighting device converts the in-vehicle battery voltage into the LED driving voltage by using a step-up / down DC / DC (Direct Current / Direct Current) converter in order to light the LED. That is, the lighting device includes a step-up / step-down DC / DC converter having a power supply capability larger than the rated power of a semiconductor light source such as an LED.
　また、ＬＥＤは昇降圧ＤＣ／ＤＣコンバータから出力される定電流により点灯する。これを実現するために、点灯装置は、昇降圧ＤＣ／ＤＣコンバータの出力電流を測定する電流測定回路と、測定結果を用いて昇降圧ＤＣ／ＤＣコンバータの出力電流をフィードバック制御する電流制御回路とを備える。電流測定回路としては複数の回路構成が考えられるが、少ない部品点数で精度よく測定する反転増幅回路を用いた回路構成がある。反転増幅型の電流測定回路と絶縁型昇降圧ＤＣ／ＤＣコンバータを組み合わせた構成の点灯装置において、電流測定回路はアースと絶縁型昇降圧ＤＣ／ＤＣコンバータの２次側との間に配置されて２次側を流れる出力電流を測定する（例えば、特許文献１参照）。 Also, the LED is lit by a constant current output from the step-up / step-down DC / DC converter. In order to achieve this, the lighting device includes a current measurement circuit that measures the output current of the step-up / step-down DC / DC converter, a current control circuit that performs feedback control of the output current of the step-up / step-down DC / DC converter using the measurement result, Is provided. A plurality of circuit configurations are conceivable as the current measuring circuit, but there is a circuit configuration using an inverting amplifier circuit that accurately measures with a small number of parts. In a lighting device having a combination of an inverting amplification type current measuring circuit and an isolated buck-boost DC / DC converter, the current measuring circuit is disposed between the ground and the secondary side of the insulated buck-boost DC / DC converter. The output current flowing on the secondary side is measured (see, for example, Patent Document 1).
国際公開第２０１３／００１５７４号International Publication No. 2013/001574
　従来の点灯装置は以上のように構成されているので、昇降圧ＤＣ／ＤＣコンバータの２次側の高電位側とＬＥＤとの接続点がショート（地絡）した場合でも、電流測定回路は２次側を流れる電流を測定し電流制御回路はフィードバック制御を行う。上記ショート故障が生じると出力負荷が小さくなり、この出力負荷に対して電流制御回路の操作量が大きくなりすぎるため、出力電圧が発振しやすくなる。 Since the conventional lighting device is configured as described above, even when the connection point between the secondary high potential side of the step-up / step-down DC / DC converter and the LED is short-circuited (ground fault), the current measuring circuit is 2 The current control circuit measures the current flowing through the secondary side and performs feedback control. When the short-circuit failure occurs, the output load becomes small, and the amount of operation of the current control circuit becomes too large for the output load, so that the output voltage tends to oscillate.
　従来、出力電圧と閾値とを比較することによってショート故障を判定する方法がある。しかしながら、ショート故障時に出力電圧が発振すると、正常時の出力電圧と発振する出力電圧のピーク値とが近接するため、正常点灯とショート故障とを判別することが困難である。 Conventionally, there is a method for determining a short circuit failure by comparing an output voltage with a threshold value. However, when the output voltage oscillates at the time of a short circuit failure, the normal output voltage and the peak value of the oscillating output voltage are close to each other, and it is difficult to distinguish between normal lighting and a short circuit failure.
　このように、出力電圧が発振するショート故障を判定することが困難であるという課題があった。 As described above, there is a problem that it is difficult to determine a short-circuit failure in which the output voltage oscillates.
　この発明は、上記のような課題を解決するためになされたもので、出力電圧が発振するショート故障を判定することを目的とする。 The present invention has been made to solve the above-described problems, and an object thereof is to determine a short-circuit failure in which an output voltage oscillates.
　この発明に係る半導体光源点灯装置は、入力電圧を出力電圧に変換して１個以上の半導体光源に供給するＤＣ／ＤＣコンバータと、ＤＣ／ＤＣコンバータの出力電圧を測定する出力電圧測定部と、ＤＣ／ＤＣコンバータの２次側の低電位側に接続されたアースと低電位側との間に配置されて２次側に流れる出力電流を測定する出力電流測定部と、出力電流測定部の測定値に基づいてＤＣ／ＤＣコンバータの出力電流が１個以上の半導体光源を点灯する駆動電流になるように制御する出力電流制御部と、ＤＣ／ＤＣコンバータの２次側の高電位側と１個以上の半導体光源のうちの最も高電位側に接続された半導体光源との間のショート故障を判定するショート判定部とを備え、ショート判定部は、１個以上の半導体光源を駆動電流で点灯している場合のＤＣ／ＤＣコンバータの出力電圧よりも低い第１の閾値電圧および第１の閾値電圧よりも低い第２の閾値電圧の各値を有し、出力電圧測定部の測定値が第１の閾値電圧よりも降下した場合にショート故障が発生している可能性があると判定して出力電流制御部に対して電流変更指示を出し、電流変更指示に基づいてＤＣ／ＤＣコンバータの出力電流が変更された状態で出力電圧測定部の測定値が第２の閾値電圧よりも降下した場合にショート故障が発生していると確定し、出力電流制御部は、ショート判定部から電流変更指示を受けた場合、ＤＣ／ＤＣコンバータの出力電流が駆動電流よりも低い検査電流になるように制御するものである。 A semiconductor light source lighting device according to the present invention includes a DC / DC converter that converts an input voltage into an output voltage and supplies the output voltage to one or more semiconductor light sources, an output voltage measurement unit that measures an output voltage of the DC / DC converter, An output current measuring unit that is arranged between the ground connected to the low potential side of the secondary side of the DC / DC converter and the low potential side and measures the output current flowing to the secondary side, and measurement of the output current measuring unit An output current control unit for controlling the output current of the DC / DC converter to be a driving current for lighting one or more semiconductor light sources based on the value, a high potential side on the secondary side of the DC / DC converter, and one A short determination unit that determines a short-circuit failure with a semiconductor light source connected to the highest potential side of the semiconductor light sources. The short determination unit lights one or more semiconductor light sources with a drive current. The Each of the first threshold voltage lower than the output voltage of the DC / DC converter and the second threshold voltage lower than the first threshold voltage, and the measured value of the output voltage measuring unit is the first When the voltage drops below the threshold voltage, it is determined that a short-circuit failure may have occurred, and a current change instruction is issued to the output current control unit. Based on the current change instruction, the output current of the DC / DC converter is When the measured value of the output voltage measurement unit falls below the second threshold voltage in the changed state, it is determined that a short circuit fault has occurred, and the output current control unit receives a current change instruction from the short determination unit. In this case, the output current of the DC / DC converter is controlled to be a test current lower than the drive current.
　この発明によれば、出力電圧測定部の測定値が第１の閾値電圧よりも降下した場合にショート故障が発生している可能性があると判定してＤＣ／ＤＣコンバータの出力電流を駆動電流よりも低い検査電流にし、電流変更指示に基づいてＤＣ／ＤＣコンバータの出力電流が変更された状態で出力電圧測定部の測定値が第２の閾値電圧よりも降下した場合にショート故障が発生していると確定するようにしたので、出力電圧が発振するショート故障を判定することができる。 According to the present invention, when the measured value of the output voltage measuring unit drops below the first threshold voltage, it is determined that there is a possibility that a short circuit failure has occurred, and the output current of the DC / DC converter is converted to the drive current. If the measured value of the output voltage measurement unit drops below the second threshold voltage when the output current of the DC / DC converter is changed based on the current change instruction, the short circuit fault occurs. Therefore, it is possible to determine a short-circuit failure in which the output voltage oscillates.
この発明の実施の形態１に係る半導体光源点灯装置の構成例を示す回路図である。It is a circuit diagram which shows the structural example of the semiconductor light source lighting device which concerns on Embodiment 1 of this invention. この発明の実施の形態１に係る半導体光源点灯装置における正常点灯時およびショート故障時の出力電圧を示すグラフである。It is a graph which shows the output voltage at the time of the normal lighting in the semiconductor light source lighting device concerning Embodiment 1 of this invention, and a short circuit failure. この発明の実施の形態１に係る半導体光源点灯装置の動作例を示すフローチャートである。It is a flowchart which shows the operation example of the semiconductor light source lighting device which concerns on Embodiment 1 of this invention. この発明の実施の形態１に係る半導体光源点灯装置における正常点灯時およびショート故障時の検査電流通電中の出力電圧を示すグラフである。It is a graph which shows the output voltage during energization of inspection current at the time of normal lighting in the semiconductor light source lighting device concerning Embodiment 1 of this invention, and at the time of a short circuit failure. 図５Ａおよび図５Ｂは、この発明の実施の形態１における出力電流制御部とショート判定部のハードウェア構成例を示す図である。5A and 5B are diagrams showing hardware configuration examples of the output current control unit and the short determination unit in the first embodiment of the present invention.
　以下、この発明をより詳細に説明するために、この発明を実施するための形態について、添付の図面に従って説明する。
実施の形態１．
　図１は、この発明の実施の形態１に係る半導体光源点灯装置１０の構成例を示す回路図である。実施の形態１では、バッテリ１、ＬＥＤ２および半導体光源点灯装置１０がＤＲＬ用の車両灯具を構成する。バッテリ１は、半導体光源点灯装置１０に入力電圧を供給する電源である。ＬＥＤ２は、ＤＲＬとして使用される半導体光源である。なお、半導体光源は、ＬＥＤに限定されるものではなく、レーザダイオード等でもよい。 Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a configuration example of a semiconductor light source lighting device 10 according to Embodiment 1 of the present invention. In the first embodiment, the battery 1, the LED 2, and the semiconductor light source lighting device 10 constitute a DRL vehicle lamp. The battery 1 is a power source that supplies an input voltage to the semiconductor light source lighting device 10. The LED 2 is a semiconductor light source used as a DRL. The semiconductor light source is not limited to the LED, and may be a laser diode or the like.
　半導体光源点灯装置１０は、主に昇降圧ＤＣ／ＤＣコンバータ１１、出力電圧測定部１７、出力電流測定部１８、出力電流制御部１９およびショート判定部２０を備える。なお、図１の構成例において、整流回路および平滑回路等の図示を省略する。 The semiconductor light source lighting device 10 mainly includes a step-up / step-down DC / DC converter 11, an output voltage measurement unit 17, an output current measurement unit 18, an output current control unit 19, and a short determination unit 20. In the configuration example of FIG. 1, the rectifier circuit, the smoothing circuit, and the like are not shown.
　昇降圧ＤＣ／ＤＣコンバータ１１は、バッテリ１から供給される入力電圧をＬＥＤ２に供給する出力電圧へ変換する。この昇降圧ＤＣ／ＤＣコンバータ１１は、例えば、絶縁型トランスを用いたフライバック方式の昇降圧ＤＣ／ＤＣコンバータである。なお、昇降圧ＤＣ／ＤＣコンバータ１１はフライバック方式の昇降圧ＤＣ／ＤＣコンバータに限定されるものではなく、バッテリ１から供給される入力電圧より低い電圧にも高い電圧にも変換可能なものであればよい。したがって、半導体光源点灯装置１０は、図１の構成例ではＤＲＬ用の１個のＬＥＤ２を点灯する目的で使用されるが、ＤＲＬ用の１個のＬＥＤ２の代わりに、前照灯用に直列に接続された複数個のＬＥＤ２を点灯することも可能である。 The step-up / step-down DC / DC converter 11 converts the input voltage supplied from the battery 1 into an output voltage supplied to the LED 2. The step-up / step-down DC / DC converter 11 is, for example, a flyback type step-up / step-down DC / DC converter using an insulating transformer. Note that the step-up / step-down DC / DC converter 11 is not limited to the flyback type step-up / step-down DC / DC converter, and can convert the input voltage supplied from the battery 1 to a voltage lower or higher. I just need it. Therefore, the semiconductor light source lighting device 10 is used for the purpose of lighting one LED 2 for DRL in the configuration example of FIG. 1, but instead of one LED 2 for DRL, it is connected in series for a headlamp. It is also possible to turn on a plurality of connected LEDs 2.
　高電位側入力端子１２は、昇降圧ＤＣ／ＤＣコンバータ１１の１次巻線の高電位側とバッテリ１の高電位側とを接続する端子である。低電位側入力端子１３は、昇降圧ＤＣ／ＤＣコンバータ１１の１次巻線の低電位側とバッテリ１の低電位側とを接続する端子である。昇降圧ＤＣ／ＤＣコンバータ１１の１次巻線の低電位側と低電位側入力端子１３との間には、スイッチング素子２１が接続される。 The high potential side input terminal 12 is a terminal for connecting the high potential side of the primary winding of the step-up / step-down DC / DC converter 11 to the high potential side of the battery 1. The low potential side input terminal 13 is a terminal for connecting the low potential side of the primary winding of the step-up / step-down DC / DC converter 11 and the low potential side of the battery 1. A switching element 21 is connected between the low potential side input terminal 13 of the primary winding of the step-up / step-down DC / DC converter 11.
　高電位側出力端子１４は、昇降圧ＤＣ／ＤＣコンバータ１１の２次巻線の高電位側とＬＥＤ２のアノードとを接続する端子である。低電位側出力端子１５は、昇降圧ＤＣ／ＤＣコンバータ１１の２次巻線の低電位側とＬＥＤ２のカソードとを接続する端子である。また、昇降圧ＤＣ／ＤＣコンバータ１１の２次巻線の低電位側は、アース１６に接続される。 The high potential side output terminal 14 is a terminal for connecting the high potential side of the secondary winding of the step-up / step-down DC / DC converter 11 and the anode of the LED 2. The low potential side output terminal 15 is a terminal for connecting the low potential side of the secondary winding of the step-up / step-down DC / DC converter 11 and the cathode of the LED 2. The low potential side of the secondary winding of the step-up / step-down DC / DC converter 11 is connected to the ground 16.
　出力電圧測定部１７は、昇降圧ＤＣ／ＤＣコンバータ１１の２次巻線の両端に接続され、昇降圧ＤＣ／ＤＣコンバータ１１の出力電圧を測定して測定値をショート判定部２０へ出力する。この出力電圧測定部１７は、例えば、抵抗等を用いた分圧回路であり、昇降圧ＤＣ／ＤＣコンバータ１１の出力電圧をショート判定部２０がＡ／Ｄ（Ａｎａｌｏｇ／Ｄｉｇｉｔａｌ）変換可能な電圧に変換する。 The output voltage measurement unit 17 is connected to both ends of the secondary winding of the step-up / step-down DC / DC converter 11, measures the output voltage of the step-up / step-down DC / DC converter 11, and outputs the measured value to the short determination unit 20. The output voltage measuring unit 17 is, for example, a voltage dividing circuit using a resistor or the like, and the output voltage of the step-up / step-down DC / DC converter 11 is converted to a voltage that the short determination unit 20 can perform A / D (Analog / Digital) conversion on. Convert.
　出力電流測定部１８は、昇降圧ＤＣ／ＤＣコンバータ１１の２次巻線の低電位側とアース１６との間に配置され、昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を測定して出力電流制御部１９へ出力する。この出力電流測定部１８は、例えば、シャント抵抗と反転増幅器とを組み合わせた回路であり、シャント抵抗に流れる電流を出力電流制御部１９がＡ／Ｄ変換可能な電圧に変換する。 The output current measuring unit 18 is disposed between the low potential side of the secondary winding of the step-up / step-down DC / DC converter 11 and the ground 16 and measures the output current of the step-up / step-down DC / DC converter 11 to control the output current. To the unit 19. The output current measuring unit 18 is, for example, a circuit combining a shunt resistor and an inverting amplifier, and converts the current flowing through the shunt resistor into a voltage that can be A / D converted by the output current control unit 19.
　出力電流制御部１９は、出力電流測定部１８の測定値に基づいて、昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を制御する。図１の構成例では、出力電流制御部１９は、フィードバック制御により出力電流測定部１８の測定値と目標電流値とが等しくなるように操作量を決定し、決定した操作量に応じたデューティ比でスイッチング素子２１をオンオフ駆動する。 The output current control unit 19 controls the output current of the step-up / step-down DC / DC converter 11 based on the measurement value of the output current measurement unit 18. In the configuration example of FIG. 1, the output current control unit 19 determines the operation amount so that the measured value of the output current measurement unit 18 and the target current value are equal by feedback control, and the duty ratio according to the determined operation amount. Thus, the switching element 21 is driven on and off.
　ショート判定部２０は、出力電圧測定部１７の測定値に基づいて、ＬＥＤ２のショート故障を判定する。このショート判定部２０は、高電位側出力端子１４とＬＥＤ２とを接続する信号線に「×」印で示す位置２２が地絡した場合、この地絡をショート故障として判定する。なお、高電位側出力端子１４と低電位側出力端子１５との間に複数個のＬＥＤ２が直列に接続されている場合、ショート判定部２０は、これらのＬＥＤ２のうちの最も高電位側出力端子１４側に配置されたＬＥＤ２と高電位側出力端子１４との間の地絡をショート故障として判定する。 The short determination unit 20 determines a short failure of the LED 2 based on the measurement value of the output voltage measurement unit 17. When the position 22 indicated by “x” is grounded on the signal line connecting the high potential side output terminal 14 and the LED 2, the short determination unit 20 determines this ground fault as a short fault. When a plurality of LEDs 2 are connected in series between the high-potential side output terminal 14 and the low-potential side output terminal 15, the short determination unit 20 is the highest potential side output terminal of these LEDs 2. A ground fault between the LED 2 arranged on the 14 side and the high potential side output terminal 14 is determined as a short circuit failure.
　図２は、この発明の実施の形態１に係る半導体光源点灯装置１０における正常点灯時およびショート故障時の出力電圧を示すグラフである。グラフの横軸は時間、縦軸はサンプリング周期ごとに出力電圧測定部１７が測定した昇降圧ＤＣ／ＤＣコンバータ１１の出力電圧である。ショート故障が発生していない正常点灯時、出力電圧測定部１７が測定する出力電圧は安定している。一方、ショート故障の発生時、出力電圧測定部１７が測定する出力電圧は発振する。発振が生じるのは、昇降圧ＤＣ／ＤＣコンバータ１１が有する電力供給能力に対してＬＥＤ２の低格電力が小さく、かつ出力電流制御部１９によるフィードバック制御の操作量が大きいためである。実施の形態１のように昇降圧ＤＣ／ＤＣコンバータ１１がＤＲＬ用のＬＥＤ２を点灯する目的で使用される場合、正常点灯時の出力電圧が小さいため、正常点灯時の出力電圧と発振する出力電圧のピーク値とが近接し、正常点灯時の出力電圧とショート故障時の出力電圧とを判別するための閾値を設定することが困難である。そのため、出力電圧が発振するショート故障を判定することが困難である。そこで、実施の形態１のショート判定部２０は、ショート故障を判定するための閾値を２種類用いて、ショート故障を２段階で判定する。以下、判定方法の具体例を説明する。 FIG. 2 is a graph showing output voltages at the time of normal lighting and a short circuit failure in the semiconductor light source lighting device 10 according to the first embodiment of the present invention. The horizontal axis of the graph is time, and the vertical axis is the output voltage of the step-up / step-down DC / DC converter 11 measured by the output voltage measuring unit 17 for each sampling period. The output voltage measured by the output voltage measuring unit 17 is stable during normal lighting when no short failure has occurred. On the other hand, when a short circuit failure occurs, the output voltage measured by the output voltage measuring unit 17 oscillates. Oscillation occurs because the lower rated power of the LED 2 is smaller than the power supply capability of the step-up / step-down DC / DC converter 11 and the amount of feedback control by the output current control unit 19 is large. When the step-up / step-down DC / DC converter 11 is used for the purpose of lighting the DRL LED 2 as in the first embodiment, the output voltage at the time of normal lighting is small and the output voltage at the time of normal lighting and the output voltage that oscillates. It is difficult to set a threshold value for discriminating between the output voltage at normal lighting and the output voltage at short-circuit failure. For this reason, it is difficult to determine a short circuit failure in which the output voltage oscillates. Therefore, the short determination unit 20 according to the first embodiment determines a short failure in two stages using two types of thresholds for determining a short failure. Hereinafter, a specific example of the determination method will be described.
　なお、高電位側出力端子１４と低電位側出力端子１５との間に複数個のＬＥＤ２が直列に接続されている場合、直列接続されたＬＥＤ２間のいずれかが地絡しても出力電圧は発振しにくい。一方、直列接続されたＬＥＤ２のうちの最も高電位側出力端子１４側に配置されたＬＥＤ２と高電位側出力端子１４との間が地絡すると出力電圧は発振する。そのため、高電位側出力端子１４と低電位側出力端子１５との間に複数個のＬＥＤ２が直列に接続されている場合にも、以下に示す判定方法を用いて出力電圧が発振するショート故障を判定できる。 When a plurality of LEDs 2 are connected in series between the high potential side output terminal 14 and the low potential side output terminal 15, the output voltage is not affected even if one of the LEDs 2 connected in series is grounded. Hard to oscillate. On the other hand, when a ground fault occurs between the LED 2 arranged on the highest potential side output terminal 14 side of the LEDs 2 connected in series and the high potential side output terminal 14, the output voltage oscillates. Therefore, even when a plurality of LEDs 2 are connected in series between the high-potential side output terminal 14 and the low-potential side output terminal 15, a short-circuit failure in which the output voltage oscillates using the determination method shown below. Can be judged.
　図３は、この発明の実施の形態１に係る半導体光源点灯装置１０の動作例を示すフローチャートである。半導体光源点灯装置１０は、図３のフローチャートに示される動作を繰り返し行う。ステップＳＴ１～ＳＴ８は１段階目のショート故障判定であり、ステップＳＴ９～ＳＴ１２は２段階目のショート故障判定である。 FIG. 3 is a flowchart showing an operation example of the semiconductor light source lighting device 10 according to the first embodiment of the present invention. The semiconductor light source lighting device 10 repeatedly performs the operation shown in the flowchart of FIG. Steps ST1 to ST8 are first stage short circuit failure determinations, and steps ST9 to ST12 are second stage short circuit failure determinations.
　ステップＳＴ１において、ショート判定部２０は、出力電圧測定部１７が最新のサンプリング周期で測定した出力電圧と、予め定められた第１の閾値電圧とを比較する。第１の閾値電圧は、ＬＥＤ２の駆動電圧より低い電圧であり、例えば（第１の閾値電圧）＝（駆動電圧×０．８）である。なお、高電位側出力端子１４と低電位側出力端子１５との間に複数個のＬＥＤ２が直列に接続されている構成において点灯するＬＥＤ２の個数が可変である場合、第１の閾値電圧は、最も少ない点灯数での駆動電圧より低い電圧とする。図２において、出力電圧が第１の閾値電圧未満になった場合、ＬＥＤ２のショート故障が疑われる。ただし、ノイズ等の外乱により出力電圧測定部１７が誤動作して出力電圧が下がった可能性もあるため、ショート判定部２０はこの時点ではショート故障とは確定しない。 In step ST1, the short determination unit 20 compares the output voltage measured by the output voltage measurement unit 17 with the latest sampling cycle with a predetermined first threshold voltage. The first threshold voltage is a voltage lower than the driving voltage of the LED 2, for example, (first threshold voltage) = (driving voltage × 0.8). When the number of LEDs 2 to be lit is variable in a configuration in which a plurality of LEDs 2 are connected in series between the high potential side output terminal 14 and the low potential side output terminal 15, the first threshold voltage is: The voltage is lower than the drive voltage at the smallest number of lighting. In FIG. 2, when the output voltage becomes less than the first threshold voltage, a short circuit failure of the LED 2 is suspected. However, since there is a possibility that the output voltage measurement unit 17 malfunctions due to a disturbance such as noise and the output voltage is lowered, the short determination unit 20 is not determined as a short failure at this time.
　ショート判定部２０は、出力電圧測定部１７が測定した出力電圧が第１の閾値電圧以上である場合（ステップＳＴ１“ＮＯ”）、ステップＳＴ２へ進む。ショート判定部２０は、出力電圧測定部１７が測定した出力電圧が第１の閾値電圧未満である場合（ステップＳＴ１“ＹＥＳ”）、ステップＳＴ３へ進む。 When the output voltage measured by the output voltage measurement unit 17 is equal to or higher than the first threshold voltage (step ST1 “NO”), the short determination unit 20 proceeds to step ST2. If the output voltage measured by the output voltage measurement unit 17 is less than the first threshold voltage (step ST1 “YES”), the short determination unit 20 proceeds to step ST3.
　ステップＳＴ２において、ショート判定部２０は、ショート故障は生じていないと判定する。したがって、出力電流制御部１９は、ＬＥＤ２の通常点灯を継続するように、昇降圧ＤＣ／ＤＣコンバータ１１を定電流制御する。 In step ST2, the short determination unit 20 determines that no short failure has occurred. Therefore, the output current control unit 19 performs constant current control of the step-up / step-down DC / DC converter 11 so as to continue the normal lighting of the LED 2.
　ステップＳＴ３において、ショート判定部２０は、内蔵する不図示のタイマをスタートさせる。 In step ST3, the short determination unit 20 starts a built-in timer (not shown).
　ステップＳＴ４において、ショート判定部２０は、タイマが計測する時間が所定時間未満である場合（ステップＳＴ４“ＮＯ”）、ステップＳＴ５へ進み、タイマが計測する時間が所定時間を経過した場合（ステップＳＴ４“ＹＥＳ”）、ステップＳＴ７へ進む。 In step ST4, when the time measured by the timer is less than the predetermined time (step ST4 “NO”), the short determination unit 20 proceeds to step ST5, and when the time measured by the timer has passed the predetermined time (step ST4). “YES”), go to step ST7.
　ステップＳＴ５において、ショート判定部２０は、出力電圧測定部１７が最新のサンプリング周期で測定した出力電圧と、第１の閾値電圧とを比較する。ショート判定部２０は、出力電圧測定部１７が測定した出力電圧が第１の閾値電圧未満である場合（ステップＳＴ５“ＹＥＳ”）、ステップＳＴ６へ進み、出力電圧測定部１７が測定した出力電圧が第１の閾値電圧以上である場合（ステップＳＴ５“ＮＯ”）、ステップＳＴ４へ戻る。 In step ST5, the short determination unit 20 compares the output voltage measured by the output voltage measurement unit 17 with the latest sampling period and the first threshold voltage. When the output voltage measured by the output voltage measurement unit 17 is less than the first threshold voltage (step ST5 “YES”), the short determination unit 20 proceeds to step ST6, and the output voltage measured by the output voltage measurement unit 17 is When the voltage is equal to or higher than the first threshold voltage (step ST5 “NO”), the process returns to step ST4.
　ステップＳＴ６において、ショート判定部２０は、ステップＳＴ５で出力電圧が第１の閾値電圧未満と判定された判定回数をカウントし、ステップＳＴ４へ戻る。 In step ST6, the short determination unit 20 counts the number of determinations in which the output voltage is determined to be less than the first threshold voltage in step ST5, and returns to step ST4.
　ステップＳＴ７において、ショート判定部２０は、所定時間における判定回数が所定回数以下である場合（ステップＳＴ７“ＮＯ”）、出力電圧が第１の閾値電圧未満になった原因がショート故障ではなくノイズ等の外乱による出力電圧測定部１７の誤動作であると判定し、ステップＳＴ８へ進む。一方、ショート判定部２０は、所定時間における判定回数が所定回数より大きい場合（ステップＳＴ７“ＹＥＳ”）、ショート故障が疑われるため、２段階目の判定を行うべくステップＳＴ９へ進む。 In step ST7, when the number of determinations in the predetermined time is less than or equal to the predetermined number of times (step ST7 “NO”), the cause that the output voltage has become less than the first threshold voltage is not a short circuit failure but noise or the like. It is determined that the output voltage measuring unit 17 is malfunctioning due to the disturbance of, and the process proceeds to step ST8. On the other hand, if the number of determinations in the predetermined time is larger than the predetermined number (step ST7 “YES”), the short determination unit 20 proceeds to step ST9 to determine the second stage because a short failure is suspected.
　ステップＳＴ８において、ショート判定部２０は、判定回数をリセットし、ステップＳＴ２へ進む。 In step ST8, the short determination unit 20 resets the number of determinations, and proceeds to step ST2.
　ステップＳＴ９において、ショート判定部２０は、昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を検査電流にするよう出力電流制御部１９へ指示する。出力電流制御部１９は、ショート判定部２０からこの指示を受けると、昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を検査電流に変化させる。検査電流は、通常点灯時の駆動電流より低い電流であり、例えば（検査電流）＝（駆動電流×０．５）である。この検査電流は、出力電流制御部１９によるフィードバック制御の操作量を小さくして出力電圧の発振を抑制するためのものである。出力電流制御部１９は、フィードバック制御の目標電流値を検査電流にすることによって昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を検査電流に変化させてもよいし、スイッチング素子２１をオンオフ駆動するデューティ比を検査電流に相当する値にすることによって昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を検査電流に変化させてもよい。 In step ST9, the short determination unit 20 instructs the output current control unit 19 to set the output current of the step-up / step-down DC / DC converter 11 to the inspection current. Upon receiving this instruction from the short determination unit 20, the output current control unit 19 changes the output current of the step-up / step-down DC / DC converter 11 to a test current. The inspection current is lower than the drive current during normal lighting, for example, (inspection current) = (drive current × 0.5). This inspection current is for reducing the amount of feedback control by the output current control unit 19 and suppressing oscillation of the output voltage. The output current control unit 19 may change the output current of the step-up / step-down DC / DC converter 11 to the inspection current by setting the target current value of the feedback control to the inspection current, or the duty ratio for driving the switching element 21 on and off. May be changed to a test current by changing the output current of the step-up / step-down DC / DC converter 11 to a value corresponding to the test current.
　図４は、この発明の実施の形態１に係る半導体光源点灯装置１０における正常点灯時およびショート故障時の検査電流通電中の出力電圧を示すグラフである。グラフの横軸は時間、縦軸はサンプリング周期ごとに出力電圧測定部１７が測定した昇降圧ＤＣ／ＤＣコンバータ１１の出力電圧である。ＬＥＤ２がショート故障している場合、昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を検査電流に変化させると出力電圧の発振が抑制されて安定する。この状態では、正常点灯時の出力電圧とショート故障時の出力電圧とのマージンが大きいため、閾値を用いて容易にショート故障を判定できるようになる。ここで、第２の閾値電圧は、第１の閾値電圧より低い電圧であり、例えば（第２の閾値電圧）＝（駆動電圧×０．５）である。この第２の閾値電圧は、ＬＥＤ２が点灯していたら有り得ない電圧である。 FIG. 4 is a graph showing the output voltage during normal operation and in the supply of the inspection current at the time of short-circuit in the semiconductor light source lighting device 10 according to the first embodiment of the present invention. The horizontal axis of the graph is time, and the vertical axis is the output voltage of the step-up / step-down DC / DC converter 11 measured by the output voltage measuring unit 17 for each sampling period. When the LED 2 is short-circuited, the output voltage oscillation is suppressed and stabilized when the output current of the step-up / step-down DC / DC converter 11 is changed to a test current. In this state, since the margin between the output voltage during normal lighting and the output voltage during a short fault is large, it is possible to easily determine a short fault using a threshold value. Here, the second threshold voltage is a voltage lower than the first threshold voltage, for example, (second threshold voltage) = (driving voltage × 0.5). This second threshold voltage is a voltage that is impossible if the LED 2 is lit.
　ステップＳＴ１０において、ショート判定部２０は、出力電圧測定部１７が最新のサンプリング周期で測定した出力電圧と、予め定められた第２の閾値電圧とを比較する。ショート判定部２０は、出力電圧測定部１７が測定した出力電圧が第２の閾値電圧以上である場合（ステップＳＴ１０“ＮＯ”）、ステップＳＴ１１へ進み、出力電圧測定部１７が測定した出力電圧が第２の閾値電圧未満である場合（ステップＳＴ１０“ＹＥＳ”）、ステップＳＴ１２へ進む。 In step ST10, the short determination unit 20 compares the output voltage measured by the output voltage measurement unit 17 with the latest sampling cycle with a predetermined second threshold voltage. When the output voltage measured by the output voltage measurement unit 17 is equal to or higher than the second threshold voltage (step ST10 “NO”), the short determination unit 20 proceeds to step ST11, and the output voltage measured by the output voltage measurement unit 17 is When the voltage is less than the second threshold voltage (step ST10 “YES”), the process proceeds to step ST12.
　ステップＳＴ１１において、ショート判定部２０は、ショート故障は生じていないと確定し、検査電流を通常点灯時の駆動電流に戻すよう出力電流制御部１９へ指示する。出力電流制御部１９は、ショート判定部２０からこの指示を受けると、昇降圧ＤＣ／ＤＣコンバータ１１の出力電流を検査電流から通常点灯時の駆動電流に変化させる。 In step ST11, the short determination unit 20 determines that no short failure has occurred, and instructs the output current control unit 19 to return the inspection current to the drive current during normal lighting. When the output current control unit 19 receives this instruction from the short determination unit 20, the output current control unit 19 changes the output current of the step-up / step-down DC / DC converter 11 from the inspection current to the drive current during normal lighting.
　ステップＳＴ１２において、ショート判定部２０は、ＬＥＤ２がショート故障したと確定する。図４に示されるショート故障時の検査電流通電中の出力電圧は図２に示されるショート故障時の駆動電流通電中の出力電圧に比べて安定するため、第２の閾値電圧を用いた２段階目の判定に要する時間は第１の閾値電圧を用いた１段階目の判定に要する時間より短くできる。図３のフローチャートにおいて第２の閾値電圧を用いた２段階目の判定（ステップＳＴ１０）に要する時間は、出力電圧測定部１７が出力電圧を測定するサンプリング周期１周期分である。 In step ST12, the short determination unit 20 determines that the LED 2 has a short circuit failure. Since the output voltage during energization of the inspection current at the time of the short fault shown in FIG. 4 is more stable than the output voltage during energization of the drive current at the time of the short fault shown in FIG. 2, two steps using the second threshold voltage are used. The time required for the eye determination can be shorter than the time required for the first stage determination using the first threshold voltage. In the flowchart of FIG. 3, the time required for the second stage determination (step ST10) using the second threshold voltage is one sampling period in which the output voltage measurement unit 17 measures the output voltage.
　なお、図３のフローチャートでは、第１の閾値電圧を用いた１段階目の判定として時間に基づく判定方法を例示したが、この方法に限定されるものではなく、比率に基づく判定を行ってもよい。例えば、ステップＳＴ３において、ショート判定部２０は、出力電圧のサンプリング回数のカウントを開始する。その後、ショート判定部２０は、サンプリング回数が所定回数になった場合、ステップＳＴ７において、このサンプリング回数に対するステップＳＴ６でカウントした判定回数の比率が所定の比率より大きい場合にショート故障を疑い、ステップＳＴ９へ進む。 In the flowchart of FIG. 3, the determination method based on time is exemplified as the first step determination using the first threshold voltage. However, the determination method is not limited to this method, and the determination based on the ratio may be performed. Good. For example, in step ST3, the short determination unit 20 starts counting the number of sampling times of the output voltage. Thereafter, when the number of times of sampling reaches a predetermined number, the short determination unit 20 suspects a short failure when the ratio of the number of determinations counted in step ST6 to the number of times of sampling is larger than the predetermined ratio in step ST7. Proceed to
　最後に、この発明の実施の形態１における出力電流制御部１９およびショート判定部２０のハードウェア構成例を説明する。
　図５Ａおよび図５Ｂは、この発明の実施の形態１における出力電流制御部１９およびショート判定部２０のハードウェア構成例を示す図である。出力電流制御部１９およびショート判定部２０の各機能は、処理回路により実現される。即ち、半導体光源点灯装置１０は、上記各機能を実現するための処理回路を備える。処理回路は、専用のハードウェアとしての処理回路１００であってもよいし、メモリ１０２に格納されるプログラムを実行するプロセッサ１０１であってもよい。 Finally, a hardware configuration example of the output current control unit 19 and the short determination unit 20 according to Embodiment 1 of the present invention will be described.
5A and 5B are diagrams showing hardware configuration examples of the output current control unit 19 and the short determination unit 20 according to Embodiment 1 of the present invention. Each function of the output current control unit 19 and the short determination unit 20 is realized by a processing circuit. That is, the semiconductor light source lighting device 10 includes a processing circuit for realizing the above functions. The processing circuit may be the processing circuit 100 as dedicated hardware, or may be the processor 101 that executes a program stored in the memory 102.
　図５Ａに示すように、処理回路１００が専用のハードウェアである場合、処理回路１００は、例えば、単一回路、複合回路、プログラム化したプロセッサ、並列プログラム化したプロセッサ、ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）、ＦＰＧＡ（Ｆｉｅｌｄ　Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）、またはこれらを組み合わせたものが該当する。出力電流制御部１９およびショート判定部２０の機能を複数の処理回路１００で実現してもよいし、各部の機能をまとめて１つの処理回路１００で実現してもよい。 As shown in FIG. 5A, when the processing circuit 100 is dedicated hardware, the processing circuit 100 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or the like. ), FPGA (Field Programmable Gate Array), or a combination thereof. The functions of the output current control unit 19 and the short determination unit 20 may be realized by a plurality of processing circuits 100, or the functions of each unit may be realized by a single processing circuit 100.
　図５Ｂに示すように、処理回路がプロセッサ１０１である場合、出力電流制御部１９およびショート判定部２０の各機能は、ソフトウェア、ファームウェア、またはソフトウェアとファームウェアとの組み合わせにより実現される。ソフトウェアまたはファームウェアはプログラムとして記述され、メモリ１０２に格納される。プロセッサ１０１は、メモリ１０２に格納されたプログラムを読みだして実行することにより、各部の機能を実現する。即ち、半導体光源点灯装置１０は、プロセッサ１０１により実行されるときに、図３のフローチャートで示されるステップが結果的に実行されることになるプログラムを格納するためのメモリ１０２を備える。また、このプログラムは、出力電流制御部１９およびショート判定部２０の手順または方法をコンピュータに実行させるものであるとも言える。 As shown in FIG. 5B, when the processing circuit is the processor 101, each function of the output current control unit 19 and the short determination unit 20 is realized by software, firmware, or a combination of software and firmware. Software or firmware is described as a program and stored in the memory 102. The processor 101 reads out and executes a program stored in the memory 102, thereby realizing the function of each unit. That is, the semiconductor light source lighting device 10 includes a memory 102 for storing a program that, when executed by the processor 101, results in the steps shown in the flowchart of FIG. Further, it can be said that this program causes a computer to execute the procedure or method of the output current control unit 19 and the short determination unit 20.
　ここで、プロセッサ１０１とは、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）、処理装置、演算装置、マイクロプロセッサ、マイクロコンピュータ、またはＤＳＰ（Ｄｉｇｉｔａｌ　Ｓｉｇｎａｌ　Ｐｒｏｃｅｓｓｏｒ）等のことである。
　メモリ１０２は、ＲＡＭ（Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）、ＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）、ＥＰＲＯＭ（Ｅｒａｓａｂｌｅ　Ｐｒｏｇｒａｍｍａｂｌｅ　ＲＯＭ）、またはフラッシュメモリ等の不揮発性もしくは揮発性の半導体メモリであってもよいし、ハードディスクまたはフレキシブルディスク等の磁気ディスクであってもよいし、ＣＤ（Ｃｏｍｐａｃｔ　Ｄｉｓｃ）またはＤＶＤ（Ｄｉｇｉｔａｌ　Ｖｅｒｓａｔｉｌｅ　Ｄｉｓｃ）等の光ディスクであってもよい。
　このメモリ１０２には、第１の閾値電圧、第２の閾値電圧、および検査電流等の情報も格納される。 Here, the processor 101 is a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like.
The memory 102 may be a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), or a flash memory, or a hard disk or a flexible disk. The magnetic disk may be an optical disk such as a CD (Compact Disc) or a DVD (Digital Versatile Disc).
The memory 102 also stores information such as the first threshold voltage, the second threshold voltage, and the inspection current.
　なお、出力電流制御部１９およびショート判定部２０の各機能について、一部を専用のハードウェアで実現し、一部をソフトウェアまたはファームウェアで実現するようにしてもよい。このように、半導体光源点灯装置１０における処理回路は、ハードウェア、ソフトウェア、ファームウェア、またはこれらの組み合わせによって、上述の各機能を実現することができる。 In addition, about each function of the output current control part 19 and the short determination part 20, you may be made to implement | achieve part by exclusive hardware and implement | achieve part by software or firmware. As described above, the processing circuit in the semiconductor light source lighting device 10 can realize the above-described functions by hardware, software, firmware, or a combination thereof.
　以上のように、実施の形態１に係る半導体光源点灯装置１０は、入力電圧を出力電圧に変換して１個以上のＬＥＤ２に供給する昇降圧ＤＣ／ＤＣコンバータ１１と、昇降圧ＤＣ／ＤＣコンバータ１１の出力電圧を測定する出力電圧測定部１７と、昇降圧ＤＣ／ＤＣコンバータ１１の２次側とアース１６との間に配置されて２次側に流れる出力電流を測定する出力電流測定部１８と、出力電流測定部１８の測定値に基づいて昇降圧ＤＣ／ＤＣコンバータ１１の出力電流が１個以上のＬＥＤ２を点灯する駆動電流になるように制御する出力電流制御部１９と、昇降圧ＤＣ／ＤＣコンバータ１１の２次側の高電位側と１個以上のＬＥＤ２のうちの最も高電位側に接続されたＬＥＤ２との間のショート故障を判定するショート判定部２０とを備える。ショート判定部２０は、第１の閾値電圧と第２の閾値電圧の各値を有し、出力電圧測定部１７の測定値が第１の閾値電圧よりも降下した場合にショート故障が発生している可能性があると判定して出力電流制御部１９に対して検査電流変更指示を出し、検査電流変更指示に基づいて昇降圧ＤＣ／ＤＣコンバータ１１の出力電流が変更された状態で出力電圧測定部１７の測定値が第２の閾値電圧よりも降下した場合にショート故障が発生していると確定する。出力電流制御部１９は、ショート判定部２０から検査電流変更指示を受けた場合、昇降圧ＤＣ／ＤＣコンバータ１１の出力電流が駆動電流よりも低い検査電流になるように制御する。ショート故障の判定を２段階で行うことにより、ショート故障時に出力電圧が発振して正常時の出力電圧と発振する出力電圧のピーク値とが近接した場合でも、ショート故障を判定することができる。 As described above, the semiconductor light source lighting device 10 according to the first embodiment includes the step-up / step-down DC / DC converter 11 that converts the input voltage into the output voltage and supplies the output voltage to one or more LEDs 2, and the step-up / step-down DC / DC converter. An output voltage measuring unit 17 that measures the output voltage of the step-up / step-down DC / DC converter 11 and an output current measuring unit 18 that is arranged between the secondary side of the step-up / step-down DC / DC converter 11 and the ground 16 and measures the output current flowing to the secondary side. An output current control unit 19 for controlling the output current of the step-up / step-down DC / DC converter 11 to be a drive current for lighting one or more LEDs 2 based on the measurement value of the output current measuring unit 18; A short determination unit 20 that determines a short circuit failure between the secondary high potential side of the DC converter 11 and the LED 2 connected to the highest potential side of the one or more LEDs 2.The short determination unit 20 has each value of the first threshold voltage and the second threshold voltage, and a short failure occurs when the measurement value of the output voltage measurement unit 17 falls below the first threshold voltage. The output current control unit 19 is instructed to change the test current and the output current of the step-up / step-down DC / DC converter 11 is changed based on the test current change instruction. When the measured value of the unit 17 falls below the second threshold voltage, it is determined that a short fault has occurred. When receiving an inspection current change instruction from the short determination unit 20, the output current control unit 19 controls the output current of the step-up / step-down DC / DC converter 11 to be an inspection current lower than the drive current. By determining the short-circuit failure in two stages, the short-circuit failure can be determined even when the output voltage oscillates at the time of the short-circuit failure and the normal output voltage and the peak value of the oscillating output voltage are close to each other.
　また、実施の形態１において検査電流が駆動電流の１／２以下であることにより、ショート故障によって昇降圧ＤＣ／ＤＣコンバータ１１の出力負荷が軽減された場合であっても、発振が抑制され安定した出力電圧を供給することが可能となる。そのため、安定した出力電圧と第２の閾値電圧との比較によってショート故障をより確実に判定することができる。 Further, in the first embodiment, since the inspection current is ½ or less of the drive current, even when the output load of the step-up / step-down DC / DC converter 11 is reduced due to a short circuit failure, oscillation is suppressed and stable. The output voltage can be supplied. Therefore, it is possible to more reliably determine a short circuit failure by comparing the stable output voltage with the second threshold voltage.
　また、実施の形態１において、出力電圧測定部１７の測定値が第２の閾値電圧よりも降下したと判定するのに要する時間より、出力電圧測定部１７の測定値が第１の閾値電圧よりも降下したと判定するのに要する時間が長く設定されていることにより、発振する出力電圧と第１の閾値電圧との比較時にノイズ等の影響を排除でき、ショート故障をより確実に判定することができる。 In the first embodiment, the measured value of the output voltage measuring unit 17 is greater than the first threshold voltage from the time required to determine that the measured value of the output voltage measuring unit 17 has dropped below the second threshold voltage. Since the time required to determine that the voltage has dropped is set longer, the influence of noise and the like can be eliminated when comparing the oscillating output voltage with the first threshold voltage, and a short-circuit failure can be determined more reliably. Can do.
　また、実施の形態１に係る車両灯具は、１個のＬＥＤ２と、１個のＬＥＤ２の定格電力の２倍以上の電力供給能力を有する昇降圧ＤＣ／ＤＣコンバータ１１を備える半導体光源点灯装置１０とで構成される。半導体光源点灯装置１０をＤＲＬ点灯用と前照灯点灯用とで兼用するような場合、半導体光源点灯装置１０は電力供給能力の大きい昇降圧ＤＣ／ＤＣコンバータ１１を備える必要がある。昇降圧ＤＣ／ＤＣコンバータ１１の電力供給能力が大きいと、上述したようにＤＲＬ点灯時にショート故障が発生すると出力電圧が発振して正常時の出力電圧と発振する出力電圧のピーク値とが近接し、正常点灯とショート故障との判別が困難になる。このような場合でもショート判定部２０のショート判定方法によりショート故障を確実に判定することができる。 Moreover, the vehicle lamp according to the first embodiment includes a semiconductor light source lighting device 10 including one LED 2 and a step-up / step-down DC / DC converter 11 having a power supply capability that is twice or more the rated power of the single LED 2. Consists of. When the semiconductor light source lighting device 10 is used for both DRL lighting and headlight lighting, the semiconductor light source lighting device 10 needs to include a step-up / step-down DC / DC converter 11 having a large power supply capability. If the power supply capability of the step-up / step-down DC / DC converter 11 is large, as described above, if a short circuit failure occurs when the DRL is lit, the output voltage oscillates and the normal output voltage and the peak value of the oscillated output voltage are close to each other. Therefore, it is difficult to distinguish between normal lighting and a short circuit failure. Even in such a case, the short failure can be reliably determined by the short determination method of the short determination unit 20.
　なお、本発明はその発明の範囲内において、実施の形態の任意の構成要素の変形、または実施の形態の任意の構成要素の省略が可能である。 In the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.
　この発明に係る半導体光源点灯装置は、出力電力が発振するショート故障を判定するようにしたので、ＤＲＬ用光源を有する車両灯具の点灯装置などに用いるのに適している。 The semiconductor light source lighting device according to the present invention is suitable for use in a lighting device for a vehicle lamp having a light source for DRL since it determines a short-circuit failure in which output power oscillates.
　１　バッテリ、２　ＬＥＤ、１０　半導体光源点灯装置、１１　昇降圧ＤＣ／ＤＣコンバータ、１２　高電位側入力端子、１３　低電位側入力端子、１４　高電位側出力端子、１５　低電位側出力端子、１６　アース、１７　出力電圧測定部、１８　出力電流測定部、１９　出力電流制御部、２０　ショート判定部、２１　スイッチング素子、２２　ショート故障位置、１００　処理回路、１０１　プロセッサ、１０２　メモリ。 1 battery, 2 LED, 10 semiconductor light source lighting device, 11 buck-boost DC / DC converter, 12 high potential side input terminal, 13 low potential side input terminal, 14 high potential side output terminal, 15 low potential side output terminal, 16 ground , 17 output voltage measurement unit, 18 output current measurement unit, 19 output current control unit, 20 short determination unit, 21 switching element, 22 short fault location, 100 processing circuit, 101 processor, 102 memory.

Claims (4)

  1. 　入力電圧を出力電圧に変換して１個以上の半導体光源に供給するＤＣ／ＤＣコンバータと、
    　前記ＤＣ／ＤＣコンバータの出力電圧を測定する出力電圧測定部と、
    　前記ＤＣ／ＤＣコンバータの２次側の低電位側に接続されたアースと前記低電位側との間に配置されて前記２次側に流れる出力電流を測定する出力電流測定部と、
    　前記出力電流測定部の測定値に基づいて前記ＤＣ／ＤＣコンバータの出力電流が前記１個以上の半導体光源を点灯する駆動電流になるように制御する出力電流制御部と、
    　前記ＤＣ／ＤＣコンバータの前記２次側の高電位側と前記１個以上の半導体光源のうちの最も前記高電位側に接続された半導体光源との間のショート故障を判定するショート判定部とを備え、
    　前記ショート判定部は、前記１個以上の半導体光源を前記駆動電流で点灯している場合の前記ＤＣ／ＤＣコンバータの出力電圧よりも低い第１の閾値電圧および前記第１の閾値電圧よりも低い第２の閾値電圧の各値を有し、前記出力電圧測定部の測定値が前記第１の閾値電圧よりも降下した場合に前記ショート故障が発生している可能性があると判定して前記出力電流制御部に対して電流変更指示を出し、前記電流変更指示に基づいて前記ＤＣ／ＤＣコンバータの出力電流が変更された状態で前記出力電圧測定部の測定値が前記第２の閾値電圧よりも降下した場合に前記ショート故障が発生していると確定し、
    　前記出力電流制御部は、前記ショート判定部から前記電流変更指示を受けた場合、前記ＤＣ／ＤＣコンバータの出力電流が前記駆動電流よりも低い検査電流になるように制御することを特徴とする半導体光源点灯装置。     A DC / DC converter that converts an input voltage into an output voltage and supplies it to one or more semiconductor light sources;
    An output voltage measuring unit for measuring an output voltage of the DC / DC converter;
    An output current measuring unit which is disposed between the ground connected to the low potential side of the secondary side of the DC / DC converter and the low potential side and measures an output current flowing to the secondary side;
    An output current control unit for controlling the output current of the DC / DC converter to be a drive current for lighting the one or more semiconductor light sources based on a measurement value of the output current measurement unit;
    A short determination unit for determining a short-circuit failure between the secondary high potential side of the DC / DC converter and the semiconductor light source connected to the highest potential side of the one or more semiconductor light sources; Prepared,
    The short determination unit includes a first threshold voltage lower than an output voltage of the DC / DC converter when the one or more semiconductor light sources are lit with the driving current, and lower than the first threshold voltage. It has each value of the second threshold voltage, and when the measured value of the output voltage measurement unit falls below the first threshold voltage, it is determined that the short fault may have occurred and A current change instruction is issued to the output current control unit, and the measured value of the output voltage measurement unit is obtained from the second threshold voltage in a state where the output current of the DC / DC converter is changed based on the current change instruction. Is determined that the short fault has occurred,
    The output current control unit controls the output current of the DC / DC converter to be an inspection current lower than the drive current when receiving the current change instruction from the short determination unit. Light source lighting device.
  2. 　前記検査電流は、前記駆動電流の１／２以下であることを特徴とする請求項１記載の半導体光源点灯装置。 2. The semiconductor light source lighting device according to claim 1, wherein the inspection current is ½ or less of the driving current.
  3. 　前記ショート判定部において前記出力電圧測定部の測定値が前記第２の閾値電圧よりも降下したと判定するのに要する時間より、前記出力電圧測定部の測定値が前記第１の閾値電圧よりも降下したと判定するのに要する時間が長く設定されていることを特徴とする請求項１記載の半導体光源点灯装置。 The measured value of the output voltage measurement unit is less than the first threshold voltage from the time required for the short determination unit to determine that the measurement value of the output voltage measurement unit has dropped below the second threshold voltage. 2. The semiconductor light source lighting device according to claim 1, wherein a time required for determining that the light has fallen is set to be long.
  4. 　１個の半導体光源と、
    　請求項１記載の半導体光源点灯装置とを備え、
    　前記半導体光源点灯装置が備えるＤＣ／ＤＣコンバータは、前記１個の半導体光源の定格電力の２倍以上の電力供給能力を有することを特徴とする車両灯具。     One semiconductor light source;
    A semiconductor light source lighting device according to claim 1,
    The DC / DC converter included in the semiconductor light source lighting device has a power supply capability that is at least twice the rated power of the one semiconductor light source.
PCT/JP2017/016804 2017-04-27 2017-04-27 Semiconductor light source lighting device and vehicle lamp WO2018198284A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP2017/016804 WO2018198284A1 (en) 2017-04-27 2017-04-27 Semiconductor light source lighting device and vehicle lamp

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2017/016804 WO2018198284A1 (en) 2017-04-27 2017-04-27 Semiconductor light source lighting device and vehicle lamp

Publications (1)

Publication Number Publication Date
WO2018198284A1 true WO2018198284A1 (en) 2018-11-01

Family

ID=63919575

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2017/016804 WO2018198284A1 (en) 2017-04-27 2017-04-27 Semiconductor light source lighting device and vehicle lamp

Country Status (1)

Country Link
WO (1) WO2018198284A1 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009111035A (en) * 2007-10-26 2009-05-21 Panasonic Electric Works Co Ltd Light emitting diode drive device, illumination device using light emitting diode drive device, in-vehicle cabin illumination device, and vehicle illumination device
JP2015026547A (en) * 2013-07-26 2015-02-05 パナソニックＩｐマネジメント株式会社 Lighting device of light-emitting element, light-emitting module, luminaire and lighting method of light-emitting element

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009111035A (en) * 2007-10-26 2009-05-21 Panasonic Electric Works Co Ltd Light emitting diode drive device, illumination device using light emitting diode drive device, in-vehicle cabin illumination device, and vehicle illumination device
JP2015026547A (en) * 2013-07-26 2015-02-05 パナソニックＩｐマネジメント株式会社 Lighting device of light-emitting element, light-emitting module, luminaire and lighting method of light-emitting element

Similar Documents

Publication Publication Date Title
US8633659B2 (en) Lighting device, headlamp apparatus and vehicle using same
US9894721B2 (en) Lighting device, headlight apparatus using the same, and vehicle using the same
JP5872833B2 (en) Semiconductor light source lighting circuit
US7964987B2 (en) Light emitting apparatus
JP5714976B2 (en) Semiconductor light source lighting circuit
US8766540B2 (en) Lighting device, headlamp lighting device, and headlamp unit and vehicle having same
JP6131510B2 (en) Lighting device, headlight device using the same, and vehicle
JP2012133943A (en) Led lighting device and lighting fixture using the same
US20180339642A1 (en) Vehicle lamp and lighting circuit of light source
JP2012028184A (en) Led lighting device
JP6783790B2 (en) Lighting circuit, vehicle lighting equipment
JP6302706B2 (en) VEHICLE LIGHT AND DRIVE DEVICE THEREOF
CN109219920B (en) Load driving device and vehicle lamp
JP2010015887A (en) Led lighting control circuit and vehicle lamp fixture equipped with this
JP5942187B2 (en) LED lighting device, vehicle lighting device and lighting fixture using the same
JP2018170255A (en) Lighting device, vehicular headlamp, and vehicle
US6583570B1 (en) Discharge lamp device for vehicle
JP6418443B2 (en) Lighting device, lighting device, and vehicle
JP2006086063A (en) Lighting control circuit of vehicular lighting fixture
WO2018198284A1 (en) Semiconductor light source lighting device and vehicle lamp
JP6238159B2 (en) Lighting device, headlight device using the same, and vehicle
JP2014197495A (en) Semiconductor light source control device
JP6314743B2 (en) Light emitting device
JP2014157785A (en) Drive circuit, and lamp for vehicles
JP6257485B2 (en) LED lighting device

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17907131

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17907131

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP