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WO2015092864A1 - Led driver circuit and method for controlling led driver circuit - Google Patents

Led driver circuit and method for controlling led driver circuit Download PDF

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Publication number
WO2015092864A1
WO2015092864A1 PCT/JP2013/083706 JP2013083706W WO2015092864A1 WO 2015092864 A1 WO2015092864 A1 WO 2015092864A1 JP 2013083706 W JP2013083706 W JP 2013083706W WO 2015092864 A1 WO2015092864 A1 WO 2015092864A1
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WO
WIPO (PCT)
Prior art keywords
led
terminal
voltage
switch element
circuit
Prior art date
Application number
PCT/JP2013/083706
Other languages
French (fr)
Japanese (ja)
Inventor
圭介 小林
章広 岡本
Original Assignee
新電元工業株式会社
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 新電元工業株式会社 filed Critical 新電元工業株式会社
Priority to JP2015511849A priority Critical patent/JP5897768B2/en
Priority to PCT/JP2013/083706 priority patent/WO2015092864A1/en
Priority to EP13899599.8A priority patent/EP3086377B1/en
Publication of WO2015092864A1 publication Critical patent/WO2015092864A1/en

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    • 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]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
    • 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]
    • H05B45/10—Controlling the intensity of the light
    • 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]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/54—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits in a series array of LEDs

Definitions

  • the present invention relates to an LED driver circuit and a method for controlling the LED driver circuit.
  • the conventional LED driver circuit 100a includes, for example, a first constant current power source (for example, a booster circuit or the like) that supplies a constant current for lighting the LED element to the first LED circuit LC1a via the Hi-side terminal TIa.
  • Step-down circuit a second constant current power source (for example, step-up circuit or step-down circuit) Ib for supplying a constant current for lighting the LED element to the second LED circuit LC2a via the Lo-side terminal TIb, 1.
  • a control unit Xa that controls the first and second constant current power sources Ia and Ib and a power source Sa that supplies power to the first and second constant current power sources Ia and Ib and the control unit Xa are provided (FIG. 2).
  • the positive electrode of the battery Ba is connected to the power source Sa via the main switch MSWa and the battery terminal TBa. Further, the negative electrode of the battery Ba is connected to the control unit Xa via the ground terminal TGa.
  • the positive electrode of the battery Ba is connected to one end of the load LOa via the relay REa, and the negative electrode of the battery Ba is connected to the other end of the load LOa.
  • the first LED switch LS1a that can be switched on / off by the user between the Hi-side terminal TIa (the output of the first constant current power supply Ia) and the ground terminal TGa is connected to the first LED circuit LC1a. Connected in series.
  • a second LED switch LS2a that can be switched on / off by the user between the Lo-side terminal TIb (output of the second constant current power supply Ib) and the ground terminal TGa is a second LED circuit LC2a. Connected in series.
  • the first LED circuit LC1a, the second LED circuit LC1b, the first LED switch LS1a, and the second LED switch LS2a constitute a headlamp unit 101a.
  • the switch detection unit Da detects the switching (on / off) state of the first and second LED switches LS1a and LS2a by the user, and controls the detection result via the switch switching information terminals TD1 and TD2. Output to part Xa.
  • the control unit Xa is in a switching (on / off) state by the user output from the first and second LED switches LS1a and LS2a detected by the switch detection unit Da. Based on the detection result (external signal), the first and second constant current power supplies Ia and Ib are controlled to supply a constant current to the LED element.
  • switching of the high beam / low beam of the headlamp unit 101a (that is, control of turning on / off the first and second LED circuits LC1a and LC2a) is executed by controlling the supply of current by the control unit Xa.
  • the conventional LED driver circuit requires first and second constant current power supplies such as a booster circuit or a step-down circuit. Further, in the conventional LED driver circuit 100a, switching on / off of the first and second LED switches LS1a and LS2a connected in series to the switch detection unit Da and the first and second LED circuits LC1a and LC2a Information (external signal) is required. In other words, the conventional LED driver circuit 100a requires external signal terminals and wiring.
  • the conventional LED driver circuit 100a has a problem that the circuit area and the manufacturing cost increase.
  • the above-described heating protection circuit does not protect the transistor according to the voltage of the LED element.
  • An LED driver circuit includes: A first LED circuit having one or a plurality of LED elements connected in series and having an anode side connected to the positive electrode of the battery, and one or a plurality of LED elements connected in series, and the battery A second LED circuit having an anode connected to the positive electrode of the LED driver circuit, and an LED driver circuit for driving the second LED circuit, A first LED terminal to which a cathode side of the first LED circuit is connected; A second LED terminal to which the cathode side of the second LED circuit is connected; A ground terminal connected to the negative electrode of the battery; A first switch element connected between the first LED terminal and the ground terminal; A second switch element connected between the second LED terminal and the ground terminal; A first voltage detection circuit for detecting a first terminal voltage of the first LED terminal; A second voltage detection circuit for detecting a second terminal voltage of the second LED terminal; A control unit that controls the first switch element and the second switch element according to the first terminal voltage and the second terminal voltage, and A first LED switch that can be switched
  • a battery voltage detection circuit for detecting a battery voltage of the battery is When the first potential difference between the battery voltage and the first terminal voltage is not more than a first specified value, the on-duty of the first switch element is reduced, Further, when the second potential difference between the battery voltage and the second terminal voltage is equal to or less than a second specified value, the on-duty of the second switch element may be reduced.
  • the controller is When the first potential difference is not more than a third specified value lower than the first specified value, the first switch element is turned off, When the second potential difference is equal to or less than a fourth specified value that is lower than the second specified value, the second switch element may be turned off.
  • the controller is When the first terminal voltage is equal to or lower than a first determination value set in advance, it is determined that a disconnection has occurred in the LED element of the first LED circuit; When the second terminal voltage is equal to or lower than a second determination value set in advance, it may be determined that a disconnection has occurred in the LED element of the second LED circuit.
  • the first determination value and the second determination value may be ground voltages.
  • the first and third on-duties may be 100% on-duty.
  • a second LED switch that can be switched on / off by a user may be connected in series with the second LED circuit between the positive electrode of the battery and the second LED terminal.
  • One end of the relay is connected to the positive electrode of the battery, the other end of the relay is connected to the anode side of the first LED circuit and the second LED circuit, A load is connected between the other end of the relay and the negative electrode of the battery,
  • the first LED circuit and the second LED circuit are LEDs of a headlamp of a motorcycle,
  • the load may be an ignition device for an engine of the two-wheeled vehicle.
  • the first switch element includes: A first MOS transistor connected between the first LED terminal and the ground terminal, the gate voltage of which is controlled by the control unit;
  • the second switch element is A second MOS transistor connected between the second LED terminal and the ground terminal, the gate voltage of which is controlled by the control unit;
  • the LED driver circuit is: A first reference voltage circuit that outputs a first reference voltage controlled by the control unit;
  • a first detection resistor connected between the first switch element and the ground terminal; The first reference voltage is compared with the first detection voltage between the first switch element and the first detection resistor, and the first reference voltage and the first detection voltage are compared.
  • a first comparator that outputs a first control signal for operating the first MOS transistor such that A first control resistor connected between the output of the first comparator and the gate of the first MOS transistor;
  • a second reference voltage circuit that outputs a second reference voltage controlled by the control unit;
  • a second detection resistor connected between the second switch element and the ground terminal; The second reference voltage is compared with a second detection voltage between the second switch element and the second detection resistor, and the second reference voltage and the second detection voltage are compared.
  • a second comparator that outputs a second control signal for operating the second MOS transistor so that A second control resistor connected between the output of the second comparator and the gate of the second MOS transistor;
  • the controller is When the first terminal voltage is less than the first upper limit value, the first reference is set so that the first switch element operates at the first on-duty by the first control signal. Control the voltage, When the first terminal voltage reaches the first upper limit value, the first switch element is operated with the second on-duty by the first control signal. Control the reference voltage, When the second terminal voltage is less than a preset second upper limit value, the second switch element is operated with the third on-duty by the second control signal. Control the reference voltage of 2, When the second terminal voltage reaches the second upper limit value, the second switch element is operated by the second control signal at the fourth on-duty by the second control signal. The reference voltage may be controlled.
  • An LED driver circuit control method includes: A first LED circuit having one or a plurality of LED elements connected in series and having an anode side connected to the positive electrode of the battery, and one or a plurality of LED elements connected in series, and the battery A second LED circuit whose anode side is connected to the positive electrode of the first LED circuit, the first LED terminal to which the cathode side of the first LED circuit is connected, and the second LED circuit A second LED terminal connected to the cathode side of the battery, a ground terminal connected to the negative electrode of the battery, a first switch element connected between the first LED terminal and the ground terminal, A second switch element connected between a second LED terminal and the ground terminal; a first voltage detection circuit for detecting a first terminal voltage of the first LED terminal; LED terminal A second voltage detection circuit for detecting a terminal voltage of the second, and a control unit for controlling the first switch element and the second switch element according to the first terminal voltage and the second terminal voltage And a method of controlling an LED driver circuit comprising: A first LED circuit having one or a pluralit
  • An LED driver circuit includes a first switch element connected between a first LED terminal and a ground terminal, and a first switch element connected between the second LED terminal and the ground terminal.
  • Two switch elements a first voltage detection circuit that detects a first terminal voltage of the first LED terminal, a second voltage detection circuit that detects a second terminal voltage of the second LED terminal, A control unit that controls the first switch element and the second switch element in accordance with the first terminal voltage and the second terminal voltage.
  • the 1st LED switch which can be switched on / off by the user between the positive electrode of a battery and the 1st LED terminal is connected in series with the 1st LED circuit.
  • the control unit controls the first switch element with the first on-duty, and the first terminal voltage is the first terminal voltage.
  • the first switch element is controlled with a second on-duty smaller than the first on-duty, and the second terminal voltage is less than a preset second upper-limit value
  • the second switch element is controlled with the third on-duty, and when the second terminal voltage reaches the second upper limit value, the second on-duty is smaller with the fourth on-duty than the third on-duty. 2 switch elements are controlled.
  • the LED driver circuit according to the present invention does not require switch switching information, and thus does not require an external signal. Moreover, a constant current power supply is not necessary.
  • the terminal and wiring of the LED driver circuit can be reduced.
  • the LED driver circuit according to the present invention suppresses the heat generation of the MOS transistor while suppressing the sudden turn-off while the light intensity of the LED element decreases when an overvoltage occurs due to a battery abnormality or the like. can do.
  • control unit reduces the on-duty of the first switch element when the first potential difference between the battery voltage and the first terminal voltage is equal to or less than the first specified value, and the battery voltage When the second potential difference between the first terminal voltage and the second terminal voltage is equal to or smaller than the second specified value, the on-duty of the second switch element is reduced.
  • control unit determines that the disconnection has occurred in the LED element of the first LED circuit when the first terminal voltage is equal to or lower than the first determination value set in advance, and the second When the terminal voltage is equal to or lower than a second determination value set in advance, it is determined that a disconnection has occurred in the LED element of the second LED circuit.
  • a disconnection of a high beam or a low beam can be detected.
  • FIG. 1 is a diagram illustrating an example of a circuit configuration of a system 1000 including an LED driver circuit 100 according to the first embodiment.
  • FIG. 2 is a diagram illustrating an example of a circuit configuration of a system 1000a including a conventional LED driver circuit 100a.
  • the LED driver circuit 100 drives the first and second LED circuits LC1 and LC2 each having one or a plurality of LED elements connected in series. (FIG. 1).
  • the positive electrode BP of the battery B is connected to the control unit X via the main switch MSW and the battery terminal TB. Further, the negative electrode BN of the battery B is connected to the control unit X via the ground terminal TG. That is, the control unit X is connected between the battery terminal TB and the ground terminal TG, and is driven by electric power supplied from the battery B.
  • the first LED circuit LC1 has one or a plurality of LED elements connected in series, and the anode side is connected to the positive electrode BP of the battery B.
  • the second LED circuit LC2 has one or a plurality of LED elements connected in series, and the anode side is connected to the positive electrode BP of the battery B.
  • these 1st LED circuit LC1 and 2nd LED circuit LC2 are LED of the headlamp of a two-wheeled vehicle, for example.
  • the LED element of the first LED circuit LC1 is a Low beam LED element
  • the LED element of the second LED circuit LC2 is a Hi beam LED element.
  • a first LED switch LS1 that can be switched on / off by the user between the positive electrode BP of the battery B and the first LED terminal TL1 is connected in series with the first LED circuit LC1.
  • a second LED switch LS2 that can be switched on / off by the user between the positive electrode BP of the battery B and the second LED terminal TL2 is connected in series with the second LED circuit LC2.
  • the first LED circuit LC1, the second LED circuit LC2, the first LED switch LS1, and the second LED switch LS2 constitute a headlamp unit 101 for a two-wheeled vehicle.
  • the main switch MSW can be switched on / off by the user.
  • a relay RE is connected between the positive electrode BP of the battery B and the anode side of the first LED circuit LC1 and the anode side of the second LED circuit LC2. That is, one end of the relay RE is connected to the positive electrode BP of the battery, and the other end of the relay RE is connected to the anode side of the first LED circuit LC1 and the second LED circuit LC2.
  • a load LO is connected between the relay RE and the negative electrode BN of the battery B.
  • This load LO is, for example, an ignition device for a two-wheeled vehicle engine.
  • the LED driver circuit 100 includes a first LED circuit LC1 having one or a plurality of LED elements connected in series and having the anode side connected to the positive electrode BP of the battery B.
  • the second LED circuit LC2 having one or a plurality of LED elements connected in series and having the anode side connected to the positive electrode BP of the battery B is driven.
  • the LED driver circuit 100 includes a first LED terminal TL1 to which the cathode side of the first LED circuit LC1 is connected, and a second LED terminal TL2 to which the cathode side of the second LED circuit LC2 is connected.
  • the LED driver circuit 100 includes a ground terminal TG connected to the negative electrode BN of the battery B, a battery terminal TB connected to the positive electrode BP of the battery B via the main switch MSW, and the battery B via the relay RE. And a voltage detection terminal TD connected to the positive electrode BP.
  • the LED driver circuit 100 is connected between the first switch element SW1 connected between the first LED terminal TL1 and the ground terminal TG, and between the second LED terminal TL2 and the ground terminal TG.
  • the LED driver circuit 100 also includes a first voltage detection circuit VD1 that detects the first terminal voltage of the first LED terminal TL1, and a second voltage that detects the second terminal voltage of the second LED terminal TL2.
  • the battery voltage detection circuit VDB detects the battery voltage of the battery B by detecting the voltage at the voltage detection terminal TD, for example.
  • the voltage detection terminal TD is connected to the positive electrode BP of the battery B via the relay RE. Therefore, when the relay RE is turned on, the battery voltage of the battery B is supplied to the voltage detection terminal TD. Therefore, the battery voltage detection circuit VDB can detect the battery voltage of the battery B by detecting the voltage at the voltage detection terminal TD.
  • the LED driver circuit 100 includes a control unit X that controls the first switch element SW1 and the second switch element SW2 according to the first terminal voltage and the second terminal voltage.
  • the control unit X is connected between the battery terminal TB and the ground terminal TG, and operates by being supplied with electric power from the battery B when the main switch MSW is turned on.
  • the first switch element SW1 is connected between the first LED terminal TL1 and the ground terminal TG, and the first MOS transistor whose gate voltage is controlled by the control unit X. M1.
  • the second switch element SW2 is connected between the second LED terminal TL2 and the ground terminal TG, and the second MOS transistor M2 whose gate voltage is controlled by the control unit X. It is.
  • the LED driver circuit 100 includes a first reference voltage circuit VR1 that outputs a first reference voltage controlled by the control unit X, and a first reference voltage circuit VR1 connected between the first switch element SW1 and the ground terminal TG. 1 detection resistor R1. Further, the LED driver circuit 100 compares the first reference voltage with the first detection voltage between the first switch element SW1 and the first detection resistor R1, and compares the first reference voltage with the first reference voltage.
  • the first comparator CON1 that outputs a first control signal for operating the first MOS transistor M1, and the output of the first comparator CON1 and the first MOS transistor M1 And a first control resistor Ra connected between the gate and the gate.
  • the control unit X controls the first reference voltage described above based on the first terminal voltage, so that the first comparator CON1 outputs and is supplied to the gate of the first MOS transistor M1.
  • the first control signal is controlled. That is, the control unit X controls the gate voltage of the first MOS transistor M1 by controlling the first reference voltage.
  • the LED driver circuit 100 also includes a second reference voltage circuit VR2 that outputs a second reference voltage controlled by the control unit X, and a second reference voltage circuit VR2 connected between the second switch element SW2 and the ground terminal TG. 2 detection resistors R2. Further, the LED driver circuit 100 compares the second reference voltage with the second detection voltage between the second switch element SW2 and the second detection resistor R2, and compares the second reference voltage with the second reference voltage. 2, the second comparator CON2 that outputs a second control signal for operating the second MOS transistor M2, and the output of the second comparator CON2 and the second MOS transistor M2 And a second control resistor Rb connected between the gate and the gate.
  • the control unit X controls the second reference voltage described above based on the second terminal voltage, so that the second comparator CON2 outputs and is supplied to the gate of the second MOS transistor M2.
  • the second control signal is controlled. That is, the control unit X controls the gate voltage of the second MOS transistor M2 by controlling the second reference voltage.
  • the control unit X controls the first reference voltage to control the first on-duty according to the first control signal.
  • the first on-duty is, for example, 100% on-duty.
  • control unit X controls the first reference voltage to reduce the first on-duty smaller than the first on-duty.
  • the first switch element SW1 is controlled with the second on-duty.
  • control unit X controls the second reference voltage to control the third on-duty according to the second control signal.
  • the third on-duty is, for example, 100% on-duty.
  • control unit X controls the second reference voltage to reduce the second on-duty smaller than the third on-duty.
  • the second switch element SW2 is controlled with the fourth on-duty.
  • the LED driver circuit 100 does not need switch switching information, and thus no external signal is required. Moreover, a constant current power supply is not necessary.
  • the terminals and wiring of the LED driver circuit 100 can be reduced.
  • the LED driver circuit 100 suppresses the heat generation of the MOS transistor while suppressing the sudden turn-off, although the brightness of the LED element is reduced when an overvoltage occurs due to a battery abnormality or the like. it can.
  • control unit X controls the first reference voltage to control the first switch.
  • the on-duty of the element SW1 is reduced.
  • the first specified value is, for example, a voltage detection with the first LED terminal TL1 when the first LED switch LS1 is turned on and any of the LED elements of the first LED circuit LC1 is short-circuited. It is set to a potential difference with the terminal TD.
  • control unit X controls the second reference voltage to control the second switch The on-duty of the element SW2 is reduced.
  • the second specified value is, for example, a voltage detection with the second LED terminal TL2 when the second LED switch LS2 is turned on and any of the LED elements of the second LED circuit LC2 is short-circuited. It is set to a potential difference with the terminal TD.
  • control unit X controls the first switch element SW1 to be turned off when the first potential difference described above is equal to or smaller than a third specified value lower than the first specified value. Also good.
  • control unit X controls to turn off the second switch element SW2 when the above-described second potential difference is equal to or less than the fourth specified value that is lower than the second specified value. May be.
  • the switch element MOS transistor
  • the switch element MOS The heat generation of the transistor
  • the positive electrode BP of the battery B and the first LED terminal TL1 are disconnected. That is, the first terminal voltage of the first LED terminal TL1 becomes the voltage (ground voltage) of the negative electrode BN of the battery B.
  • the control unit X determines that the disconnection has occurred in the LED element of the first LED circuit LC1 when the above-described first terminal voltage is equal to or lower than the first determination value set in advance.
  • the first determination value is, for example, a ground voltage (voltage of the negative electrode BN of the battery B).
  • the positive electrode BP of the battery B and the second LED terminal TL2 are blocked. That is, the second terminal voltage of the second LED terminal TL2 becomes the voltage (ground voltage) of the negative electrode BN of the battery B.
  • control unit X determines that a disconnection has occurred in the LED element of the second LED circuit LC2 when the above-described second terminal voltage is equal to or lower than the preset second determination value.
  • the second determination value is, for example, the ground voltage (the voltage of the negative electrode BN of the battery B).
  • control unit X can detect the disconnection of the LED element based on the first terminal voltage and the second terminal voltage. That is, the LED driver circuit 100 can detect disconnection of a high beam or a low beam in a headlamp of a two-wheeled vehicle, for example.
  • control unit X when the main switch MSW is turned on by the user, the control unit X is supplied with power from the battery B and operates (starts up).
  • the relay RE When the main switch MSW is turned on, the relay RE is turned on. As a result, power can be supplied from the battery B to the headlamp unit 101. At this time, if the first and second LED switches LS1 are turned off, no current flows through the first and second LED circuits LC1 and LC2.
  • the first terminal voltage is lower than the ground voltage, that is, the first upper limit value. Furthermore, the second terminal voltage is less than the ground voltage, that is, the second upper limit value.
  • control unit X controls the first reference voltage to control the first on-duty ( For example, the first switch element SW1 is controlled with an on-duty of 100%.
  • control unit X controls the second reference voltage, thereby controlling the third on-duty ( For example, the second switch element SW2 is controlled with an on-duty of 100%.
  • the first LED switch LS1 is turned on by the user.
  • the first switch element SW1 is controlled with the first on-duty, a predetermined current flows through the first LED circuit LC1, and the LED element emits light.
  • the second LED switch LS2 is turned on by the user.
  • the second switch element SW2 is controlled with the third on-duty, a predetermined current flows through the second LED circuit LC2, and the LED element emits light.
  • the LED driver circuit 100 does not need switch switching information, an external signal is not required. Moreover, a constant current power supply is not necessary.
  • the first terminal voltage reaches the first upper limit value
  • the second terminal voltage reaches the second upper limit value
  • the control unit X controls the first reference voltage so that the first control signal is smaller than the first on-duty.
  • the first switch element SW1 is controlled with the second on-duty.
  • control unit X controls the second reference voltage, thereby reducing the second terminal voltage smaller than the third on-duty by the second control signal.
  • the second switch element SW2 is controlled with an on-duty of 4.
  • the LED driver circuit 100 generates heat of the switch element (MOS transistor) while suppressing the sudden turn-off while the light intensity of the LED element decreases when an overvoltage occurs due to a battery abnormality or the like. Can be suppressed.
  • MOS transistor switch element
  • the control unit X controls the first reference voltage to thereby control the first switch element.
  • the on-duty of SW1 is reduced.
  • the control unit X controls the second reference voltage to thereby control the second switch element.
  • the on-duty of SW2 is reduced.
  • the LED driver circuit 100 includes the first switch element SW1 connected between the first LED terminal TL1 and the ground terminal TG, and the second LED terminal TL2.
  • the second switch element SW2 connected between the ground terminal TG, the first voltage detection circuit VD1 for detecting the first terminal voltage of the first LED terminal TL1, and the second of the second LED terminal TL2.
  • a second voltage detection circuit VD2 that detects a terminal voltage of 2 and a control unit X that controls the first switch element SW1 and the second switch element SW2 according to the first terminal voltage and the second terminal voltage And comprising.
  • the 1st LED switch which can be switched on / off by the user between the positive electrode BP of the battery and the first LED terminal TL1 is connected in series with the first LED circuit LC1.
  • the control unit X controls the first switch element SW1 with the first on-duty so that the first terminal voltage is When the first upper limit value is reached, the first switch element SW1 is controlled with a second on-duty smaller than the first on-duty, and the second terminal voltage is set to a second upper limit value set in advance. If less than the third on-duty, the second switch element SW2 is controlled, and if the second terminal voltage reaches the second upper limit, the fourth on-duty is smaller than the third on-duty. The second switch element SW2 is controlled with on-duty.
  • the LED driver circuit 100 does not require information on switch switching, and thus no external signal is required. Moreover, a constant current power supply is not necessary.
  • the terminals and wiring of the LED driver circuit 100 can be reduced.
  • the LED driver circuit 100 reduces the light intensity of the LED element when an overvoltage occurs due to a battery abnormality or the like, but suppresses the sudden turn-off and suppresses heat generation of the MOS transistor. Can be suppressed.
  • control unit X reduces the on-duty of the first switch element SW1 when the first potential difference between the battery voltage and the first terminal voltage is equal to or less than the first specified value, and When the second potential difference between the battery voltage and the second terminal voltage is equal to or less than the second specified value, the on-duty of the second switch element SW2 is reduced.
  • the control unit X determines that a disconnection has occurred in the LED element of the first LED circuit LC1, and When the terminal voltage of 2 is equal to or lower than the second determination value set in advance, it is determined that a disconnection has occurred in the LED element of the second LED circuit LC2.
  • the LED driver circuit 100 can detect a disconnection of a high beam or a low beam in a headlamp of a two-wheeled vehicle, for example.

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Abstract

If a first terminal voltage is less than a preset first upper limit, a control unit in this LED driver circuit controls a first switch element using a first duty cycle, and if the first terminal voltage has reached the first upper limit, the control unit controls the first switch element using a second duty cycle that is lower than the first duty cycle. If a second terminal voltage is less than a preset second upper limit, the control unit controls a second switch element using a third duty cycle, and if the second terminal voltage has reached the second upper limit, the control unit controls the second switch element using a fourth duty cycle that is lower than the third duty cycle.

Description

ＬＥＤドライバ回路、および、ＬＥＤドライバ回路の制御方法LED driver circuit and method for controlling LED driver circuit
　本発明は、ＬＥＤドライバ回路、および、ＬＥＤドライバ回路の制御方法に関する。 The present invention relates to an LED driver circuit and a method for controlling the LED driver circuit.
　従来、直列に接続された複数のＬＥＤ素子を有するＬＥＤ回路を駆動するＬＥＤドライバ回路がある（例えば、特開２００８－２１８４５７号公報参照）。 Conventionally, there is an LED driver circuit that drives an LED circuit having a plurality of LED elements connected in series (see, for example, JP-A-2008-218457).
　例えば、従来のＬＥＤドライバ回路１００ａは、例えば、Ｈｉ側端子ＴＩａを介して第１のＬＥＤ回路ＬＣ１ａにＬＥＤ素子を点灯するための定電流を供給する第１の定電流電源（例えば、昇圧回路又は降圧回路）と、Ｌｏ側端子ＴＩｂを介して第２のＬＥＤ回路ＬＣ２ａにＬＥＤ素子を点灯するための定電流を供給する第２の定電流電源（例えば、昇圧回路又は降圧回路）Ｉｂと、第１、第２の定電流電源Ｉａ、Ｉｂを制御する制御部Ｘａと、第１、第２の定電流電源Ｉａ、Ｉｂおよび制御部Ｘａに電力を供給する電源Ｓａとを備える（図２）。 For example, the conventional LED driver circuit 100a includes, for example, a first constant current power source (for example, a booster circuit or the like) that supplies a constant current for lighting the LED element to the first LED circuit LC1a via the Hi-side terminal TIa. Step-down circuit), a second constant current power source (for example, step-up circuit or step-down circuit) Ib for supplying a constant current for lighting the LED element to the second LED circuit LC2a via the Lo-side terminal TIb, 1. A control unit Xa that controls the first and second constant current power sources Ia and Ib and a power source Sa that supplies power to the first and second constant current power sources Ia and Ib and the control unit Xa are provided (FIG. 2).
　そして、バッテリＢａの正極は、メインスイッチＭＳＷａ、及びバッテリ端子ＴＢａを介して、電源Ｓａに接続されている。また、バッテリＢａの負極は、接地端子ＴＧａを介して、制御部Ｘａに接続されている。 And the positive electrode of the battery Ba is connected to the power source Sa via the main switch MSWa and the battery terminal TBa. Further, the negative electrode of the battery Ba is connected to the control unit Xa via the ground terminal TGa.
　また、バッテリＢａの正極は、リレーＲＥａを介して、負荷ＬＯａの一端に接続され、バッテリＢａの負極は、負荷ＬＯａの他端に接続されている。 Further, the positive electrode of the battery Ba is connected to one end of the load LOa via the relay REa, and the negative electrode of the battery Ba is connected to the other end of the load LOa.
　そして、Ｈｉ側端子ＴＩａ（第１の定電流電源Ｉａの出力）と接地端子ＴＧａとの間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチＬＳ１ａが、第１のＬＥＤ回路ＬＣ１ａと直列に接続されている。 The first LED switch LS1a that can be switched on / off by the user between the Hi-side terminal TIa (the output of the first constant current power supply Ia) and the ground terminal TGa is connected to the first LED circuit LC1a. Connected in series.
　同様に、Ｌｏ側端子ＴＩｂ（第２の定電流電源Ｉｂの出力）と接地端子ＴＧａとの間で、ユーザによりオン／オフが切り替え可能な第２のＬＥＤスイッチＬＳ２ａが、第２のＬＥＤ回路ＬＣ２ａと直列に接続されている。 Similarly, a second LED switch LS2a that can be switched on / off by the user between the Lo-side terminal TIb (output of the second constant current power supply Ib) and the ground terminal TGa is a second LED circuit LC2a. Connected in series.
　なお、これらの第１のＬＥＤ回路ＬＣ１ａと、第２のＬＥＤ回路ＬＣ１ｂと、第１のＬＥＤスイッチＬＳ１ａと、第２のＬＥＤスイッチＬＳ２ａとにより、ヘッドランプユニット１０１ａが構成される。 The first LED circuit LC1a, the second LED circuit LC1b, the first LED switch LS1a, and the second LED switch LS2a constitute a headlamp unit 101a.
　そして、スイッチ検出部Ｄａは、第１、第２のＬＥＤスイッチＬＳ１ａ、ＬＳ２ａのユーザによる切り替え（オン／オフ）の状態を検出し、この検出結果をスイッチ切り替え情報端子ＴＤ１、ＴＤ２を介して、制御部Ｘａに出力する。 The switch detection unit Da detects the switching (on / off) state of the first and second LED switches LS1a and LS2a by the user, and controls the detection result via the switch switching information terminals TD1 and TD2. Output to part Xa.
　ここで、この従来のＬＥＤドライバ回路１００ａにおいて、制御部Ｘａは、スイッチ検出部Ｄａが検出した第１、第２のＬＥＤスイッチＬＳ１ａ、ＬＳ２ａから出力されたユーザによる切り替え（オン／オフ）の状態の検出結果（外部信号）に基づいて、第１、第２の定電流電源Ｉａ、ＩｂによりＬＥＤ素子に定電流を供給する制御を行っている。 Here, in this conventional LED driver circuit 100a, the control unit Xa is in a switching (on / off) state by the user output from the first and second LED switches LS1a and LS2a detected by the switch detection unit Da. Based on the detection result (external signal), the first and second constant current power supplies Ia and Ib are controlled to supply a constant current to the LED element.
　そして、この制御部Ｘａによる電流の供給の制御により、ヘッドランプユニット１０１ａのＨｉｇｈビーム／Ｌｏｗビームの切り替え（すなわち、第１、第２のＬＥＤ回路ＬＣ１ａ、ＬＣ２ａの点灯／消灯の制御）が実行される。 Then, switching of the high beam / low beam of the headlamp unit 101a (that is, control of turning on / off the first and second LED circuits LC1a and LC2a) is executed by controlling the supply of current by the control unit Xa. The
　また、従来、定電流電源の出力を制御するトランジスタの加熱保護をする加熱保護回路がある（例えば、特開２０１０－２７７２２６号公報参照）。 Also, conventionally, there is a heat protection circuit for protecting the transistor that controls the output of the constant current power supply (see, for example, Japanese Patent Application Laid-Open No. 2010-277226).
　既述のように、従来のＬＥＤドライバ回路は、昇圧回路又は降圧回路等の第１、第２の定電流電源が必要になる。さらに、従来のＬＥＤドライバ回路１００ａにおいては、スイッチ検出部Ｄａおよび第１、第２のＬＥＤ回路ＬＣ１ａ、ＬＣ２ａに直列に接続された第１、第２のＬＥＤスイッチＬＳ１ａ、ＬＳ２ａのオン／オフの切り替えの情報（外部信号）が必要になる。すなわち、従来のＬＥＤドライバ回路１００ａは、外部信号用の端子、配線が必要になる。 As described above, the conventional LED driver circuit requires first and second constant current power supplies such as a booster circuit or a step-down circuit. Further, in the conventional LED driver circuit 100a, switching on / off of the first and second LED switches LS1a and LS2a connected in series to the switch detection unit Da and the first and second LED circuits LC1a and LC2a Information (external signal) is required. In other words, the conventional LED driver circuit 100a requires external signal terminals and wiring.
　このように、従来のＬＥＤドライバ回路１００ａは、回路面積や製造コストが増大する問題がある。 Thus, the conventional LED driver circuit 100a has a problem that the circuit area and the manufacturing cost increase.
　さらに、既述の加熱保護回路は、ＬＥＤ素子の電圧に応じて、トランジスタを保護するものではない。 Furthermore, the above-described heating protection circuit does not protect the transistor according to the voltage of the LED element.
　本発明の一態様に係る実施例に従ったＬＥＤドライバ回路は、
　１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリの正極にアノード側が接続された第１のＬＥＤ回路と、１つ又は直列に接続された複数のＬＥＤ素子を有し且つ前記バッテリの正極にアノード側が接続された第２のＬＥＤ回路と、を駆動するＬＥＤドライバ回路であって、
　前記第１のＬＥＤ回路のカソード側が接続される第１のＬＥＤ端子と、
　前記第２のＬＥＤ回路のカソード側が接続される第２のＬＥＤ端子と、
　前記バッテリの負極に接続される接地端子と、
　前記第１のＬＥＤ端子と前記接地端子との間に接続された第１のスイッチ素子と、
　前記第２のＬＥＤ端子と前記接地端子との間に接続された第２のスイッチ素子と、
　前記第１のＬＥＤ端子の第１の端子電圧を検出する第１の電圧検出回路と、
　前記第２のＬＥＤ端子の第２の端子電圧を検出する第２の電圧検出回路と、
　前記第１の端子電圧および前記第２の端子電圧に応じて、前記第１のスイッチ素子および前記第２のスイッチ素子を制御する制御部と、を備え、
　前記バッテリの正極と前記第１のＬＥＤ端子との間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチが、前記第１のＬＥＤ回路と直列に接続されており、
　前記制御部は、
　前記第１の端子電圧が予め設定された第１の上限値未満の場合には、第１のオンデューティで前記第１のスイッチ素子を制御し、
　前記第１の端子電圧が前記第１の上限値に達した場合には、前記第１のオンデューティより小さい第２のオンデューティで前記第１のスイッチ素子を制御し、
　前記第２の端子電圧が予め設定された第２の上限値未満の場合には、第３のオンデューティで前記第２のスイッチ素子を制御し、
　前記第２の端子電圧が前記第２の上限値に達した場合には、前記第３のオンデューティより小さい第４のオンデューティで前記第２のスイッチ素子を制御する。 An LED driver circuit according to an embodiment of one aspect of the present invention includes:
A first LED circuit having one or a plurality of LED elements connected in series and having an anode side connected to the positive electrode of the battery, and one or a plurality of LED elements connected in series, and the battery A second LED circuit having an anode connected to the positive electrode of the LED driver circuit, and an LED driver circuit for driving the second LED circuit,
A first LED terminal to which a cathode side of the first LED circuit is connected;
A second LED terminal to which the cathode side of the second LED circuit is connected;
A ground terminal connected to the negative electrode of the battery;
A first switch element connected between the first LED terminal and the ground terminal;
A second switch element connected between the second LED terminal and the ground terminal;
A first voltage detection circuit for detecting a first terminal voltage of the first LED terminal;
A second voltage detection circuit for detecting a second terminal voltage of the second LED terminal;
A control unit that controls the first switch element and the second switch element according to the first terminal voltage and the second terminal voltage, and
A first LED switch that can be switched on / off by a user between the positive electrode of the battery and the first LED terminal is connected in series with the first LED circuit;
The controller is
When the first terminal voltage is less than a preset first upper limit value, the first switch element is controlled with a first on-duty;
When the first terminal voltage reaches the first upper limit value, the first switch element is controlled with a second on-duty smaller than the first on-duty;
When the second terminal voltage is less than a preset second upper limit value, the second switch element is controlled with a third on-duty;
When the second terminal voltage reaches the second upper limit value, the second switch element is controlled with a fourth on-duty smaller than the third on-duty.
　前記ＬＥＤドライバ回路において、
　前記バッテリのバッテリ電圧を検出するバッテリ電圧検出回路をさらに備え、
　前記制御部は、
　前記バッテリ電圧と前記第１の端子電圧との第１の電位差が、第１の規定値以下である場合には、前記第１のスイッチ素子のオンデューティを低下させ、
　また、前記バッテリ電圧と前記第２の端子電圧との第２の電位差が、第２の規定値以下である場合には、前記第２のスイッチ素子のオンデューティを低下させるようにしてもよい。 In the LED driver circuit,
A battery voltage detection circuit for detecting a battery voltage of the battery;
The controller is
When the first potential difference between the battery voltage and the first terminal voltage is not more than a first specified value, the on-duty of the first switch element is reduced,
Further, when the second potential difference between the battery voltage and the second terminal voltage is equal to or less than a second specified value, the on-duty of the second switch element may be reduced.
　前記ＬＥＤドライバ回路において、
　前記制御部は、
　前記第１の電位差が、前記第１の規定値よりも低い第３の規定値以下である場合には、前記第１のスイッチ素子をオフし、
　前記第２の電位差が、前記第２の規定値よりも低い第４の規定値以下である場合には、前記第２のスイッチ素子をオフするようにしてもよい。 In the LED driver circuit,
The controller is
When the first potential difference is not more than a third specified value lower than the first specified value, the first switch element is turned off,
When the second potential difference is equal to or less than a fourth specified value that is lower than the second specified value, the second switch element may be turned off.
　前記ＬＥＤドライバ回路において、
　前記制御部は、
　前記第１の端子電圧が予め設定された第１の判断値以下である場合には、前記第１のＬＥＤ回路のＬＥＤ素子に断線が発生していると判断し、
　前記第２の端子電圧が予め設定された第２の判断値以下である場合には、前記第２のＬＥＤ回路のＬＥＤ素子に断線が発生していると判断するようにしてもよい。 In the LED driver circuit,
The controller is
When the first terminal voltage is equal to or lower than a first determination value set in advance, it is determined that a disconnection has occurred in the LED element of the first LED circuit;
When the second terminal voltage is equal to or lower than a second determination value set in advance, it may be determined that a disconnection has occurred in the LED element of the second LED circuit.
　前記ＬＥＤドライバ回路において、
　前記第１の判断値および前記第２の判断値は、接地電圧であるようにしてもよい。 In the LED driver circuit,
The first determination value and the second determination value may be ground voltages.
　前記ＬＥＤドライバ回路において、
　前記第１および第３のオンデューティは、１００％のオンデューティであるようにしてもよい。 In the LED driver circuit,
The first and third on-duties may be 100% on-duty.
　前記ＬＥＤドライバ回路において、
　前記バッテリの正極と前記第２のＬＥＤ端子との間で、ユーザによりオン／オフが切り替え可能な第２のＬＥＤスイッチが前記第２のＬＥＤ回路と直列に接続されているようにしてもよい。 In the LED driver circuit,
A second LED switch that can be switched on / off by a user may be connected in series with the second LED circuit between the positive electrode of the battery and the second LED terminal.
　前記ＬＥＤドライバ回路において、
　リレーの一端が前記バッテリの正極に接続され、前記リレーの他端が前記第１のＬＥＤ回路および前記第２のＬＥＤ回路のアノード側に接続され、
　前記リレーの他端と前記バッテリの負極との間に負荷が接続され、
　前記第１のＬＥＤ回路および前記第２のＬＥＤ回路は、２輪車のヘッドランプのＬＥＤであり、
　前記負荷は、前記２輪車のエンジンの点火装置であるようにしてもよい。 In the LED driver circuit,
One end of the relay is connected to the positive electrode of the battery, the other end of the relay is connected to the anode side of the first LED circuit and the second LED circuit,
A load is connected between the other end of the relay and the negative electrode of the battery,
The first LED circuit and the second LED circuit are LEDs of a headlamp of a motorcycle,
The load may be an ignition device for an engine of the two-wheeled vehicle.
　前記ＬＥＤドライバ回路において、
　前記第１のスイッチ素子は、
　前記第１のＬＥＤ端子と前記接地端子との間に接続され、前記制御部によりゲート電圧が制御される第１のＭＯＳトランジスタであり、
　前記第２のスイッチ素子は、
　前記第２のＬＥＤ端子と前記接地端子との間に接続され、前記制御部によりゲート電圧が制御される第２のＭＯＳトランジスタであり、
　前記ＬＥＤドライバ回路は、
　前記制御部により制御される第１の基準電圧を出力する第１の基準電圧回路と、
　前記第１のスイッチ素子と前記接地端子との間に接続された第１の検出用抵抗と、
　前記第１の基準電圧と、前記第１のスイッチ素子と前記第１の検出用抵抗との間の第１の検出電圧とを比較し、前記第１の基準電圧と前記第１の検出電圧とが等しくなるように、前記第１のＭＯＳトランジスタを動作させる第１の制御信号を出力する第１のコンパレータと、
　前記第１のコンパレータの出力と前記第１のＭＯＳトランジスタのゲートとの間に接続された第１の制御用抵抗と、
　前記制御部により制御される第２の基準電圧を出力する第２の基準電圧回路と、
　前記第２のスイッチ素子と前記接地端子との間に接続された第２の検出用抵抗と、
　前記第２の基準電圧と、前記第２のスイッチ素子と前記第２の検出用抵抗との間の第２の検出電圧とを比較し、前記第２の基準電圧と前記第２の検出電圧とが等しくなるように、前記第２のＭＯＳトランジスタを動作させる第２の制御信号を出力する第２のコンパレータと、
　前記第２のコンパレータの出力と前記第２のＭＯＳトランジスタのゲートとの間に接続された第２の制御用抵抗と、をさらに備え、
　前記制御部は、
　前記第１の端子電圧が前記第１の上限値未満の場合には、前記第１の制御信号により前記第１のオンデューティで前記第１のスイッチ素子が動作するように、前記第１の基準電圧を制御し、
　前記第１の端子電圧が前記第１の上限値に達した場合には、前記第１の制御信号により前記第２のオンデューティで前記第１のスイッチ素子が動作するように、前記第１の基準電圧を制御し、
　前記第２の端子電圧が予め設定された第２の上限値未満の場合には、前記第２の制御信号により前記第３のオンデューティで前記第２のスイッチ素子が動作するように、前記第２の基準電圧を制御し、
　前記第２の端子電圧が前記第２の上限値に達した場合には、前記第２の制御信号により前記第４のオンデューティで前記第２のスイッチ素子が動作するように、前記第２の基準電圧を制御するようにしてもよい。 In the LED driver circuit,
The first switch element includes:
A first MOS transistor connected between the first LED terminal and the ground terminal, the gate voltage of which is controlled by the control unit;
The second switch element is
A second MOS transistor connected between the second LED terminal and the ground terminal, the gate voltage of which is controlled by the control unit;
The LED driver circuit is:
A first reference voltage circuit that outputs a first reference voltage controlled by the control unit;
A first detection resistor connected between the first switch element and the ground terminal;
The first reference voltage is compared with the first detection voltage between the first switch element and the first detection resistor, and the first reference voltage and the first detection voltage are compared. A first comparator that outputs a first control signal for operating the first MOS transistor such that
A first control resistor connected between the output of the first comparator and the gate of the first MOS transistor;
A second reference voltage circuit that outputs a second reference voltage controlled by the control unit;
A second detection resistor connected between the second switch element and the ground terminal;
The second reference voltage is compared with a second detection voltage between the second switch element and the second detection resistor, and the second reference voltage and the second detection voltage are compared. A second comparator that outputs a second control signal for operating the second MOS transistor so that
A second control resistor connected between the output of the second comparator and the gate of the second MOS transistor;
The controller is
When the first terminal voltage is less than the first upper limit value, the first reference is set so that the first switch element operates at the first on-duty by the first control signal. Control the voltage,
When the first terminal voltage reaches the first upper limit value, the first switch element is operated with the second on-duty by the first control signal. Control the reference voltage,
When the second terminal voltage is less than a preset second upper limit value, the second switch element is operated with the third on-duty by the second control signal. Control the reference voltage of 2,
When the second terminal voltage reaches the second upper limit value, the second switch element is operated by the second control signal at the fourth on-duty by the second control signal. The reference voltage may be controlled.
　本発明の一態様に係る実施例に従ったＬＥＤドライバ回路の制御方法は、
　１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリの正極にアノード側が接続された第１のＬＥＤ回路と、１つ又は直列に接続された複数のＬＥＤ素子を有し且つ前記バッテリの正極にアノード側が接続された第２のＬＥＤ回路と、を駆動するＬＥＤドライバ回路であって、前記第１のＬＥＤ回路のカソード側が接続される第１のＬＥＤ端子と、前記第２のＬＥＤ回路のカソード側が接続される第２のＬＥＤ端子と、前記バッテリの負極に接続される接地端子と、前記第１のＬＥＤ端子と前記接地端子との間に接続された第１のスイッチ素子と、前記第２のＬＥＤ端子と前記接地端子との間に接続された第２のスイッチ素子と、前記第１のＬＥＤ端子の第１の端子電圧を検出する第１の電圧検出回路と、前記第２のＬＥＤ端子の第２の端子電圧を検出する第２の電圧検出回路と、前記第１の端子電圧および前記第２の端子電圧に応じて、前記第１のスイッチ素子および前記第２のスイッチ素子を制御する制御部と、を備えたＬＥＤドライバ回路の制御方法において、
　前記バッテリの正極と前記第１のＬＥＤ端子との間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチが、前記第１のＬＥＤ回路と直列に接続されており、
　前記制御部は、
　前記第１の端子電圧が予め設定された第１の上限値未満の場合には、第１のオンデューティで前記第１のスイッチ素子を制御し、
　前記第１の端子電圧が前記第１の上限値に達した場合には、前記第１のオンデューティより小さい第２のオンデューティで前記第１のスイッチ素子を制御し、
　前記第２の端子電圧が予め設定された第２の上限値未満の場合には、第３のオンデューティで前記第２のスイッチ素子を制御し、
　前記第２の端子電圧が前記第２の上限値に達した場合には、前記第３のオンデューティより小さい第４のオンデューティで前記第２のスイッチ素子を制御する。 An LED driver circuit control method according to an embodiment of the present invention includes:
A first LED circuit having one or a plurality of LED elements connected in series and having an anode side connected to the positive electrode of the battery, and one or a plurality of LED elements connected in series, and the battery A second LED circuit whose anode side is connected to the positive electrode of the first LED circuit, the first LED terminal to which the cathode side of the first LED circuit is connected, and the second LED circuit A second LED terminal connected to the cathode side of the battery, a ground terminal connected to the negative electrode of the battery, a first switch element connected between the first LED terminal and the ground terminal, A second switch element connected between a second LED terminal and the ground terminal; a first voltage detection circuit for detecting a first terminal voltage of the first LED terminal; LED terminal A second voltage detection circuit for detecting a terminal voltage of the second, and a control unit for controlling the first switch element and the second switch element according to the first terminal voltage and the second terminal voltage And a method of controlling an LED driver circuit comprising:
A first LED switch that can be switched on / off by a user between the positive electrode of the battery and the first LED terminal is connected in series with the first LED circuit;
The controller is
When the first terminal voltage is less than a preset first upper limit value, the first switch element is controlled with a first on-duty;
When the first terminal voltage reaches the first upper limit value, the first switch element is controlled with a second on-duty smaller than the first on-duty;
When the second terminal voltage is less than a preset second upper limit value, the second switch element is controlled with a third on-duty;
When the second terminal voltage reaches the second upper limit value, the second switch element is controlled with a fourth on-duty smaller than the third on-duty.
　本発明の一態様に係るＬＥＤドライバ回路は、第１のＬＥＤ端子と接地端子との間に接続された第１のスイッチ素子と、第２のＬＥＤ端子と接地端子との間に接続された第２のスイッチ素子と、第１のＬＥＤ端子の第１の端子電圧を検出する第１の電圧検出回路と、第２のＬＥＤ端子の第２の端子電圧を検出する第２の電圧検出回路と、第１の端子電圧および第２の端子電圧に応じて、第１のスイッチ素子および第２のスイッチ素子を制御する制御部と、を備える。 An LED driver circuit according to an aspect of the present invention includes a first switch element connected between a first LED terminal and a ground terminal, and a first switch element connected between the second LED terminal and the ground terminal. Two switch elements, a first voltage detection circuit that detects a first terminal voltage of the first LED terminal, a second voltage detection circuit that detects a second terminal voltage of the second LED terminal, A control unit that controls the first switch element and the second switch element in accordance with the first terminal voltage and the second terminal voltage.
　そして、バッテリの正極と第１のＬＥＤ端子との間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチが、第１のＬＥＤ回路と直列に接続されている。 And the 1st LED switch which can be switched on / off by the user between the positive electrode of a battery and the 1st LED terminal is connected in series with the 1st LED circuit.
　そして、制御部は、第１の端子電圧が予め設定された第１の上限値未満の場合には、第１のオンデューティで第１のスイッチ素子を制御し、第１の端子電圧が第１の上限値に達した場合には、第１のオンデューティより小さい第２のオンデューティで第１のスイッチ素子を制御し、第２の端子電圧が予め設定された第２の上限値未満の場合には、第３のオンデューティで第２のスイッチ素子を制御し、第２の端子電圧が第２の上限値に達した場合には、第３のオンデューティより小さい第４のオンデューティで第２のスイッチ素子を制御する。 Then, when the first terminal voltage is less than a preset first upper limit value, the control unit controls the first switch element with the first on-duty, and the first terminal voltage is the first terminal voltage. When the first switch element is controlled with a second on-duty smaller than the first on-duty, and the second terminal voltage is less than a preset second upper-limit value The second switch element is controlled with the third on-duty, and when the second terminal voltage reaches the second upper limit value, the second on-duty is smaller with the fourth on-duty than the third on-duty. 2 switch elements are controlled.
　これにより、本発明に係るＬＥＤドライバ回路は、スイッチ切り替えの情報が不要になるので、外部信号が不要になる。また、定電流電源が不要になる。 Thus, the LED driver circuit according to the present invention does not require switch switching information, and thus does not require an external signal. Moreover, a constant current power supply is not necessary.
　すなわち、ＬＥＤドライバ回路の端子、配線等を削減することができる。 That is, the terminal and wiring of the LED driver circuit can be reduced.
　さらに、本発明に係るＬＥＤドライバ回路は、バッテリ異常時等で、過電圧となった場合に、ＬＥＤ素子の光度は、低下するが、急に消灯するのを抑制しつつ、ＭＯＳトランジスタの発熱を抑制することができる。 Furthermore, the LED driver circuit according to the present invention suppresses the heat generation of the MOS transistor while suppressing the sudden turn-off while the light intensity of the LED element decreases when an overvoltage occurs due to a battery abnormality or the like. can do.
　さらに、制御部は、バッテリ電圧と第１の端子電圧との第１の電位差が、第１の規定値以下である場合には、第１のスイッチ素子のオンデューティを低下させ、また、バッテリ電圧と第２の端子電圧との第２の電位差が、第２の規定値以下である場合には、第２のスイッチ素子のオンデューティを低下させる。 Further, the control unit reduces the on-duty of the first switch element when the first potential difference between the battery voltage and the first terminal voltage is equal to or less than the first specified value, and the battery voltage When the second potential difference between the first terminal voltage and the second terminal voltage is equal to or smaller than the second specified value, the on-duty of the second switch element is reduced.
　これにより、バッテリ電圧とＬＥＤ端子の電圧との電位差が規定値以下の場合（すなわち、ＬＥＤ素子の少なくともいずれかがショートした場合）に、スイッチ素子（ＭＯＳトランジスタ）のオンデューティを低下させて、スイッチ素子（ＭＯＳトランジスタ）の発熱を抑制させることができる。 This reduces the on-duty of the switch element (MOS transistor) when the potential difference between the battery voltage and the LED terminal voltage is equal to or less than a specified value (that is, when at least one of the LED elements is short-circuited). Heat generation of the element (MOS transistor) can be suppressed.
　さらに、制御部は、第１の端子電圧が予め設定された第１の判断値以下である場合には、第１のＬＥＤ回路のＬＥＤ素子に断線が発生していると判断し、第２の端子電圧が予め設定された第２の判断値以下である場合には、第２のＬＥＤ回路のＬＥＤ素子に断線が発生していると判断する。 Further, the control unit determines that the disconnection has occurred in the LED element of the first LED circuit when the first terminal voltage is equal to or lower than the first determination value set in advance, and the second When the terminal voltage is equal to or lower than a second determination value set in advance, it is determined that a disconnection has occurred in the LED element of the second LED circuit.
　これにより、Ｌｏ、ＨｉのＬＥＤ端子の電圧がゼロ（判断値以下）である場合には、ＨｉｇｈビームまたはＬｏｗビームのＬＥＤ素子に、断線が発生したと判断できる。 Thereby, when the voltages of the Lo and Hi LED terminals are zero (below the judgment value), it can be determined that a disconnection has occurred in the LED element of the High beam or the Low beam.
　このように、例えば、２輪車のヘッドランプにおいて、ＨｉｇｈビームまたはＬｏｗビームの断線を検出することができる。 Thus, for example, in a headlamp of a two-wheeled vehicle, a disconnection of a high beam or a low beam can be detected.
図１は、第１の実施形態に係るＬＥＤドライバ回路１００を含むシステム１０００の回路構成の一例を示す図である。FIG. 1 is a diagram illustrating an example of a circuit configuration of a system 1000 including an LED driver circuit 100 according to the first embodiment. 図２は、従来のＬＥＤドライバ回路１００ａを含むシステム１０００ａの回路構成の一例を示す図である。FIG. 2 is a diagram illustrating an example of a circuit configuration of a system 1000a including a conventional LED driver circuit 100a.
　以下、本発明に係る実施形態について図面に基づいて説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
第１の実施形態First embodiment
　第１の実施形態に係るシステム１０００において、ＬＥＤドライバ回路１００は、１つ又は直列に接続された複数のＬＥＤ素子を有する第１、第２のＬＥＤ回路ＬＣ１、ＬＣ２を駆動するようになっている（図１）。 In the system 1000 according to the first embodiment, the LED driver circuit 100 drives the first and second LED circuits LC1 and LC2 each having one or a plurality of LED elements connected in series. (FIG. 1).
　ここで、バッテリＢの正極ＢＰは、メインスイッチＭＳＷ、バッテリ端子ＴＢを介して、制御部Ｘに接続されている。また、バッテリＢの負極ＢＮは、接地端子ＴＧを介して、制御部Ｘに接続されている。すなわち、制御部Ｘは、バッテリ端子ＴＢと接地端子ＴＧとの間に接続され、バッテリＢから供給される電力により駆動するようになっている。 Here, the positive electrode BP of the battery B is connected to the control unit X via the main switch MSW and the battery terminal TB. Further, the negative electrode BN of the battery B is connected to the control unit X via the ground terminal TG. That is, the control unit X is connected between the battery terminal TB and the ground terminal TG, and is driven by electric power supplied from the battery B.
　そして、第１のＬＥＤ回路ＬＣ１は、１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリＢの正極ＢＰにアノード側が接続されている。 The first LED circuit LC1 has one or a plurality of LED elements connected in series, and the anode side is connected to the positive electrode BP of the battery B.
　そして、第２のＬＥＤ回路ＬＣ２は、１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリＢの正極ＢＰにアノード側が接続されている。 The second LED circuit LC2 has one or a plurality of LED elements connected in series, and the anode side is connected to the positive electrode BP of the battery B.
　なお、これらの第１のＬＥＤ回路ＬＣ１および第２のＬＥＤ回路ＬＣ２は、例えば、２輪車のヘッドランプのＬＥＤである。そして、例えば、第１のＬＥＤ回路ＬＣ１のＬＥＤ素子は、ＬｏｗビームのＬＥＤ素子であり、第２のＬＥＤ回路ＬＣ２のＬＥＤ素子は、ＨｉビームのＬＥＤ素子である。 In addition, these 1st LED circuit LC1 and 2nd LED circuit LC2 are LED of the headlamp of a two-wheeled vehicle, for example. For example, the LED element of the first LED circuit LC1 is a Low beam LED element, and the LED element of the second LED circuit LC2 is a Hi beam LED element.
　また、バッテリＢの正極ＢＰと第１のＬＥＤ端子ＴＬ１との間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチＬＳ１が、第１のＬＥＤ回路ＬＣ１と直列に接続されている。 Further, a first LED switch LS1 that can be switched on / off by the user between the positive electrode BP of the battery B and the first LED terminal TL1 is connected in series with the first LED circuit LC1.
　この第１のＬＥＤスイッチＬＳ１がユーザによりオンに制御されることにより、第１のＬＥＤ回路ＬＣ１に流れる電流が流れる状態になる。一方、第１のＬＥＤスイッチＬＳ１がユーザによりオフに制御されることにより、第１のＬＥＤ回路ＬＣ１に流れる電流が遮断された状態になる。 When the first LED switch LS1 is turned on by the user, a current flowing through the first LED circuit LC1 flows. On the other hand, when the first LED switch LS1 is turned off by the user, the current flowing through the first LED circuit LC1 is cut off.
　また、バッテリＢの正極ＢＰと第２のＬＥＤ端子ＴＬ２との間で、ユーザによりオン／オフが切り替え可能な第２のＬＥＤスイッチＬＳ２が、第２のＬＥＤ回路ＬＣ２と直列に接続されている。 Also, a second LED switch LS2 that can be switched on / off by the user between the positive electrode BP of the battery B and the second LED terminal TL2 is connected in series with the second LED circuit LC2.
　この第２のＬＥＤスイッチＬＳ２がユーザによりオンに制御されることにより、第２のＬＥＤ回路ＬＣ２に流れる電流が流れる状態になる。一方、第２のＬＥＤスイッチＬＳ２がユーザによりオフに制御されることにより、第２のＬＥＤ回路ＬＣ２に流れる電流が遮断された状態になる。 When the second LED switch LS2 is turned on by the user, a current flowing through the second LED circuit LC2 flows. On the other hand, when the second LED switch LS2 is turned off by the user, the current flowing through the second LED circuit LC2 is cut off.
　なお、これらの第１のＬＥＤ回路ＬＣ１と、第２のＬＥＤ回路ＬＣ２と、第１のＬＥＤスイッチＬＳ１と、第２のＬＥＤスイッチＬＳ２とにより、２輪車のヘッドランプユニット１０１が構成される。 The first LED circuit LC1, the second LED circuit LC2, the first LED switch LS1, and the second LED switch LS2 constitute a headlamp unit 101 for a two-wheeled vehicle.
　メインスイッチＭＳＷは、ユーザによりオン／オフが切り替え可能になっている。　
　また、バッテリＢの正極ＢＰと、第１のＬＥＤ回路ＬＣ１のアノード側および第２のＬＥＤ回路ＬＣ２のアノード側との間に、リレーＲＥが接続されている。すなわち、リレーＲＥの一端がバッテリの正極ＢＰに接続され、リレーＲＥの他端が第１のＬＥＤ回路ＬＣ１および第２のＬＥＤ回路ＬＣ２のアノード側に接続されている。 The main switch MSW can be switched on / off by the user.
A relay RE is connected between the positive electrode BP of the battery B and the anode side of the first LED circuit LC1 and the anode side of the second LED circuit LC2. That is, one end of the relay RE is connected to the positive electrode BP of the battery, and the other end of the relay RE is connected to the anode side of the first LED circuit LC1 and the second LED circuit LC2.
　なお、メインスイッチＭＳＷがオンすることにより、このリレーＲＥのコイルに電流が流れて、リレーＲＥがオンするようになっている。 When the main switch MSW is turned on, a current flows through the coil of the relay RE so that the relay RE is turned on.
　また、リレーＲＥとバッテリＢの負極ＢＮとの間に負荷ＬＯが接続されている。この負荷ＬＯは、例えば、２輪車のエンジンの点火装置である。 Further, a load LO is connected between the relay RE and the negative electrode BN of the battery B. This load LO is, for example, an ignition device for a two-wheeled vehicle engine.
　ここで、図１に示すように、ＬＥＤドライバ回路１００は、１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリＢの正極ＢＰにアノード側が接続された第１のＬＥＤ回路ＬＣ１と、１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリＢの正極ＢＰにアノード側が接続された第２のＬＥＤ回路ＬＣ２と、を駆動する。 Here, as shown in FIG. 1, the LED driver circuit 100 includes a first LED circuit LC1 having one or a plurality of LED elements connected in series and having the anode side connected to the positive electrode BP of the battery B. The second LED circuit LC2 having one or a plurality of LED elements connected in series and having the anode side connected to the positive electrode BP of the battery B is driven.
　このＬＥＤドライバ回路１００は、第１のＬＥＤ回路ＬＣ１のカソード側が接続される第１のＬＥＤ端子ＴＬ１と、第２のＬＥＤ回路ＬＣ２のカソード側が接続される第２のＬＥＤ端子ＴＬ２と、を備える。 The LED driver circuit 100 includes a first LED terminal TL1 to which the cathode side of the first LED circuit LC1 is connected, and a second LED terminal TL2 to which the cathode side of the second LED circuit LC2 is connected.
　また、ＬＥＤドライバ回路１００は、バッテリＢの負極ＢＮに接続される接地端子ＴＧと、メインスイッチＭＳＷを介してバッテリＢの正極ＢＰに接続されるバッテリ端子ＴＢと、リレーＲＥを介してバッテリＢの正極ＢＰに接続される電圧検出端子ＴＤと、を備える。 Further, the LED driver circuit 100 includes a ground terminal TG connected to the negative electrode BN of the battery B, a battery terminal TB connected to the positive electrode BP of the battery B via the main switch MSW, and the battery B via the relay RE. And a voltage detection terminal TD connected to the positive electrode BP.
　また、ＬＥＤドライバ回路１００は、第１のＬＥＤ端子ＴＬ１と接地端子ＴＧとの間に接続された第１のスイッチ素子ＳＷ１と、第２のＬＥＤ端子ＴＬ２と接地端子ＴＧとの間に接続された第２のスイッチ素子ＳＷ２と、を備える。 The LED driver circuit 100 is connected between the first switch element SW1 connected between the first LED terminal TL1 and the ground terminal TG, and between the second LED terminal TL2 and the ground terminal TG. A second switch element SW2.
　また、ＬＥＤドライバ回路１００は、第１のＬＥＤ端子ＴＬ１の第１の端子電圧を検出する第１の電圧検出回路ＶＤ１と、第２のＬＥＤ端子ＴＬ２の第２の端子電圧を検出する第２の電圧検出回路ＶＤ２と、バッテリＢのバッテリ電圧を検出するバッテリ電圧検出回路ＶＤＢと、を備える。 The LED driver circuit 100 also includes a first voltage detection circuit VD1 that detects the first terminal voltage of the first LED terminal TL1, and a second voltage that detects the second terminal voltage of the second LED terminal TL2. A voltage detection circuit VD2; and a battery voltage detection circuit VDB that detects a battery voltage of the battery B.
　なお、バッテリ電圧検出回路ＶＤＢは、例えば、電圧検出端子ＴＤの電圧を検出することにより、バッテリＢのバッテリ電圧を検出する。 The battery voltage detection circuit VDB detects the battery voltage of the battery B by detecting the voltage at the voltage detection terminal TD, for example.
　ここで、既述のように、電圧検出端子ＴＤは、リレーＲＥを介して、バッテリＢの正極ＢＰに接続されている。したがって、リレーＲＥがオンすることにより、電圧検出端子ＴＤにバッテリＢのバッテリ電圧が供給されることとなる。そこで、バッテリ電圧検出回路ＶＤＢは、この電圧検出端子ＴＤの電圧を検出することにより、バッテリＢのバッテリ電圧を検出することができる。 Here, as described above, the voltage detection terminal TD is connected to the positive electrode BP of the battery B via the relay RE. Therefore, when the relay RE is turned on, the battery voltage of the battery B is supplied to the voltage detection terminal TD. Therefore, the battery voltage detection circuit VDB can detect the battery voltage of the battery B by detecting the voltage at the voltage detection terminal TD.
　また、ＬＥＤドライバ回路１００は、第１の端子電圧および第２の端子電圧に応じて、第１のスイッチ素子ＳＷ１および第２のスイッチ素子ＳＷ２を制御する制御部Ｘを備える。この制御部Ｘは、バッテリ端子ＴＢと接地端子ＴＧとの間に接続され、メインスイッチＭＳＷがオンすることによりバッテリＢから電力が供給されて動作する。 Further, the LED driver circuit 100 includes a control unit X that controls the first switch element SW1 and the second switch element SW2 according to the first terminal voltage and the second terminal voltage. The control unit X is connected between the battery terminal TB and the ground terminal TG, and operates by being supplied with electric power from the battery B when the main switch MSW is turned on.
　ここで、第１のスイッチ素子ＳＷ１は、図１に示すように、第１のＬＥＤ端子ＴＬ１と接地端子ＴＧとの間に接続され、制御部Ｘによりゲート電圧が制御される第１のＭＯＳトランジスタＭ１である。また、第２のスイッチ素子ＳＷ２は、図１に示すように、第２のＬＥＤ端子ＴＬ２と接地端子ＴＧとの間に接続され、制御部Ｘによりゲート電圧が制御される第２のＭＯＳトランジスタＭ２である。 Here, as shown in FIG. 1, the first switch element SW1 is connected between the first LED terminal TL1 and the ground terminal TG, and the first MOS transistor whose gate voltage is controlled by the control unit X. M1. Further, as shown in FIG. 1, the second switch element SW2 is connected between the second LED terminal TL2 and the ground terminal TG, and the second MOS transistor M2 whose gate voltage is controlled by the control unit X. It is.
　また、ＬＥＤドライバ回路１００は、制御部Ｘにより制御される第１の基準電圧を出力する第１の基準電圧回路ＶＲ１と、第１のスイッチ素子ＳＷ１と接地端子ＴＧとの間に接続された第１の検出用抵抗Ｒ１と、を備える。さらに、ＬＥＤドライバ回路１００は、第１の基準電圧と、第１のスイッチ素子ＳＷ１と第１の検出用抵抗Ｒ１との間の第１の検出電圧とを比較し、第１の基準電圧と第１の検出電圧とが等しくなるように、第１のＭＯＳトランジスタＭ１を動作させる第１の制御信号を出力する第１のコンパレータＣＯＮ１と、第１のコンパレータＣＯＮ１の出力と第１のＭＯＳトランジスタＭ１のゲートとの間に接続された第１の制御用抵抗Ｒａとを備える。 The LED driver circuit 100 includes a first reference voltage circuit VR1 that outputs a first reference voltage controlled by the control unit X, and a first reference voltage circuit VR1 connected between the first switch element SW1 and the ground terminal TG. 1 detection resistor R1. Further, the LED driver circuit 100 compares the first reference voltage with the first detection voltage between the first switch element SW1 and the first detection resistor R1, and compares the first reference voltage with the first reference voltage. The first comparator CON1 that outputs a first control signal for operating the first MOS transistor M1, and the output of the first comparator CON1 and the first MOS transistor M1 And a first control resistor Ra connected between the gate and the gate.
　なお、制御部Ｘは、第１の端子電圧に基づいて、上述の第１の基準電圧を制御することにより、第１のコンパレータＣＯＮ１が出力し且つ第１のＭＯＳトランジスタＭ１のゲートに供給される第１の制御信号を制御する。すなわち、制御部Ｘは、第１の基準電圧を制御することにより、第１のＭＯＳトランジスタＭ１のゲート電圧を制御するようになっている。 The control unit X controls the first reference voltage described above based on the first terminal voltage, so that the first comparator CON1 outputs and is supplied to the gate of the first MOS transistor M1. The first control signal is controlled. That is, the control unit X controls the gate voltage of the first MOS transistor M1 by controlling the first reference voltage.
　また、ＬＥＤドライバ回路１００は、制御部Ｘにより制御される第２の基準電圧を出力する第２の基準電圧回路ＶＲ２と、第２のスイッチ素子ＳＷ２と接地端子ＴＧとの間に接続された第２の検出用抵抗Ｒ２と、を備える。さらに、ＬＥＤドライバ回路１００は、第２の基準電圧と、第２のスイッチ素子ＳＷ２と第２の検出用抵抗Ｒ２との間の第２の検出電圧とを比較し、第２の基準電圧と第２の検出電圧とが等しくなるように、第２のＭＯＳトランジスタＭ２を動作させる第２の制御信号を出力する第２のコンパレータＣＯＮ２と、第２のコンパレータＣＯＮ２の出力と第２のＭＯＳトランジスタＭ２のゲートとの間に接続された第２の制御用抵抗Ｒｂと、をさらに備える。 The LED driver circuit 100 also includes a second reference voltage circuit VR2 that outputs a second reference voltage controlled by the control unit X, and a second reference voltage circuit VR2 connected between the second switch element SW2 and the ground terminal TG. 2 detection resistors R2. Further, the LED driver circuit 100 compares the second reference voltage with the second detection voltage between the second switch element SW2 and the second detection resistor R2, and compares the second reference voltage with the second reference voltage. 2, the second comparator CON2 that outputs a second control signal for operating the second MOS transistor M2, and the output of the second comparator CON2 and the second MOS transistor M2 And a second control resistor Rb connected between the gate and the gate.
　なお、制御部Ｘは、第２の端子電圧に基づいて、上述の第２の基準電圧を制御することにより、第２のコンパレータＣＯＮ２が出力し且つ第２のＭＯＳトランジスタＭ２のゲートに供給される第２の制御信号を制御する。すなわち、制御部Ｘは、第２の基準電圧を制御することにより、第２のＭＯＳトランジスタＭ２のゲート電圧を制御するようになっている。 The control unit X controls the second reference voltage described above based on the second terminal voltage, so that the second comparator CON2 outputs and is supplied to the gate of the second MOS transistor M2. The second control signal is controlled. That is, the control unit X controls the gate voltage of the second MOS transistor M2 by controlling the second reference voltage.
　また、制御部Ｘは、第１の端子電圧が予め設定された第１の上限値未満の場合には、第１の基準電圧を制御することにより、第１の制御信号により第１のオンデューティで第１のスイッチ素子ＳＷ１を制御する。なお、この第１のオンデューティは、例えば、１００％のオンデューティである。 In addition, when the first terminal voltage is less than a preset first upper limit value, the control unit X controls the first reference voltage to control the first on-duty according to the first control signal. To control the first switch element SW1. The first on-duty is, for example, 100% on-duty.
　また、制御部Ｘは、第１の端子電圧が第１の上限値に達した場合には、第１の基準電圧を制御することにより、第１の制御信号により上記第１のオンデューティより小さい第２のオンデューティで第１のスイッチ素子ＳＷ１を制御する。 In addition, when the first terminal voltage reaches the first upper limit value, the control unit X controls the first reference voltage to reduce the first on-duty smaller than the first on-duty. The first switch element SW1 is controlled with the second on-duty.
　また、制御部Ｘは、第２の端子電圧が予め設定された第２の上限値未満の場合には、第２の基準電圧を制御することにより、第２の制御信号により第３のオンデューティで第２のスイッチ素子ＳＷ２を制御する。なお、この第３のオンデューティは、例えば、１００％のオンデューティである。 In addition, when the second terminal voltage is less than a preset second upper limit value, the control unit X controls the second reference voltage to control the third on-duty according to the second control signal. To control the second switch element SW2. The third on-duty is, for example, 100% on-duty.
　また、制御部Ｘは、第２の端子電圧が第２の上限値に達した場合には、第２の基準電圧を制御することにより、第２の制御信号により上記第３のオンデューティより小さい第４のオンデューティで第２のスイッチ素子ＳＷ２を制御する。 In addition, when the second terminal voltage reaches the second upper limit value, the control unit X controls the second reference voltage to reduce the second on-duty smaller than the third on-duty. The second switch element SW2 is controlled with the fourth on-duty.
　これにより、ＬＥＤドライバ回路１００は、スイッチ切り替えの情報が不要になるので、外部信号が不要になる。また、定電流電源が不要になる。 Thus, the LED driver circuit 100 does not need switch switching information, and thus no external signal is required. Moreover, a constant current power supply is not necessary.
　すなわち、ＬＥＤドライバ回路１００の端子、配線等を削減することができる。 That is, the terminals and wiring of the LED driver circuit 100 can be reduced.
　さらに、ＬＥＤドライバ回路１００は、バッテリ異常時等で、過電圧となった場合に、ＬＥＤ素子の光度は、低下するが、急に消灯するのを抑制しつつ、ＭＯＳトランジスタの発熱を抑制することができる。 Further, the LED driver circuit 100 suppresses the heat generation of the MOS transistor while suppressing the sudden turn-off, although the brightness of the LED element is reduced when an overvoltage occurs due to a battery abnormality or the like. it can.
　また、制御部Ｘは、バッテリ電圧と第１の端子電圧との第１の電位差が、第１の規定値以下である場合には、第１の基準電圧を制御することにより、第１のスイッチ素子ＳＷ１のオンデューティを低下させる。 In addition, when the first potential difference between the battery voltage and the first terminal voltage is equal to or less than the first specified value, the control unit X controls the first reference voltage to control the first switch. The on-duty of the element SW1 is reduced.
　なお、この第１の規定値は、例えば、第１のＬＥＤスイッチＬＳ１がオンし且つ第１のＬＥＤ回路ＬＣ１のＬＥＤ素子の何れかがショートしている場合における第１のＬＥＤ端子ＴＬ１と電圧検出端子ＴＤとの間の電位差に設定される。 The first specified value is, for example, a voltage detection with the first LED terminal TL1 when the first LED switch LS1 is turned on and any of the LED elements of the first LED circuit LC1 is short-circuited. It is set to a potential difference with the terminal TD.
　また、制御部Ｘは、バッテリ電圧と第２の端子電圧との第２の電位差が、第２の規定値以下である場合には、第２の基準電圧を制御することにより、第２のスイッチ素子ＳＷ２のオンデューティを低下させる。 In addition, when the second potential difference between the battery voltage and the second terminal voltage is equal to or smaller than the second specified value, the control unit X controls the second reference voltage to control the second switch The on-duty of the element SW2 is reduced.
　なお、この第２の規定値は、例えば、第２のＬＥＤスイッチＬＳ２がオンし且つ第２のＬＥＤ回路ＬＣ２のＬＥＤ素子の何れかがショートしている場合における第２のＬＥＤ端子ＴＬ２と電圧検出端子ＴＤとの間の電位差に設定される。 The second specified value is, for example, a voltage detection with the second LED terminal TL2 when the second LED switch LS2 is turned on and any of the LED elements of the second LED circuit LC2 is short-circuited. It is set to a potential difference with the terminal TD.
　これにより、バッテリ電圧とＬＥＤ端子の電圧との電位差が規定値以下の場合（すなわち、ＬＥＤ素子の少なくともいずれかがショートした場合等）に、スイッチ素子（ＭＯＳトランジスタ）のオンデューティを低下させて、スイッチ素子（ＭＯＳトランジスタ）の発熱を抑制させることができる。 Thereby, when the potential difference between the battery voltage and the LED terminal voltage is equal to or less than the specified value (that is, when at least one of the LED elements is short-circuited), the on-duty of the switch element (MOS transistor) is reduced, Heat generation of the switch element (MOS transistor) can be suppressed.
　特に、制御部Ｘは、既述の第１の電位差が、第１の規定値よりも低い第３の規定値以下である場合には、第１のスイッチ素子ＳＷ１をオフするように制御してもよい。 In particular, the control unit X controls the first switch element SW1 to be turned off when the first potential difference described above is equal to or smaller than a third specified value lower than the first specified value. Also good.
　同様に、制御部Ｘは、既述の第２の電位差が、第２の規定値よりも低い第４の規定値以下である場合には、第２のスイッチ素子ＳＷ２をオフするように制御してもよい。 Similarly, the control unit X controls to turn off the second switch element SW2 when the above-described second potential difference is equal to or less than the fourth specified value that is lower than the second specified value. May be.
　これにより、バッテリ電圧とＬＥＤ端子の電圧との電位差が規定値以下の場合（すなわち、ＬＥＤ素子の少なくともいずれかがショートした場合）に、スイッチ素子（ＭＯＳトランジスタ）をオフさせて、スイッチ素子（ＭＯＳトランジスタ）の発熱をより確実に抑制させることができる。 As a result, when the potential difference between the battery voltage and the LED terminal voltage is equal to or less than the specified value (that is, when at least one of the LED elements is short-circuited), the switch element (MOS transistor) is turned off, and the switch element (MOS The heat generation of the transistor) can be more reliably suppressed.
　ここで、第１のＬＥＤ回路ＬＣ１のＬＥＤ素子に断線が発生した場合、バッテリＢの正極ＢＰと第１のＬＥＤ端子ＴＬ１との間は、遮断される。すなわち、第１のＬＥＤ端子ＴＬ１の第１の端子電圧は、バッテリＢの負極ＢＮの電圧（接地電圧）になる。 Here, when a disconnection occurs in the LED element of the first LED circuit LC1, the positive electrode BP of the battery B and the first LED terminal TL1 are disconnected. That is, the first terminal voltage of the first LED terminal TL1 becomes the voltage (ground voltage) of the negative electrode BN of the battery B.
　そこで、制御部Ｘは、既述の第１の端子電圧が予め設定された第１の判断値以下である場合には、第１のＬＥＤ回路ＬＣ１のＬＥＤ素子に断線が発生していると判断する。なお、この第１の判断値は、例えば、接地電圧（バッテリＢの負極ＢＮの電圧）である。 Therefore, the control unit X determines that the disconnection has occurred in the LED element of the first LED circuit LC1 when the above-described first terminal voltage is equal to or lower than the first determination value set in advance. To do. Note that the first determination value is, for example, a ground voltage (voltage of the negative electrode BN of the battery B).
　同様に、第２のＬＥＤ回路ＬＣ２のＬＥＤ素子に断線が発生した場合、バッテリＢの正極ＢＰと第２のＬＥＤ端子ＴＬ２との間は、遮断される。すなわち、第２のＬＥＤ端子ＴＬ２の第２の端子電圧は、バッテリＢの負極ＢＮの電圧（接地電圧）になる。 Similarly, when a disconnection occurs in the LED element of the second LED circuit LC2, the positive electrode BP of the battery B and the second LED terminal TL2 are blocked. That is, the second terminal voltage of the second LED terminal TL2 becomes the voltage (ground voltage) of the negative electrode BN of the battery B.
　そこで、制御部Ｘは、既述の第２の端子電圧が予め設定された第２の判断値以下である場合には、第２のＬＥＤ回路ＬＣ２のＬＥＤ素子に断線が発生していると判断する。なお、この第２の判断値は、例えば、接地電圧（バッテリＢの負極ＢＮの電圧）である。 Therefore, the control unit X determines that a disconnection has occurred in the LED element of the second LED circuit LC2 when the above-described second terminal voltage is equal to or lower than the preset second determination value. To do. Note that the second determination value is, for example, the ground voltage (the voltage of the negative electrode BN of the battery B).
　このように、制御部Ｘは、第１の端子電圧および第２の端子電圧に基づいて、ＬＥＤ素子の断線を検出することができる。すなわち、ＬＥＤドライバ回路１００は、例えば、２輪車のヘッドランプにおいて、ＨｉｇｈビームまたはＬｏｗビームの断線を検出することができる。 Thus, the control unit X can detect the disconnection of the LED element based on the first terminal voltage and the second terminal voltage. That is, the LED driver circuit 100 can detect disconnection of a high beam or a low beam in a headlamp of a two-wheeled vehicle, for example.
　次に、以上のような構成を有するＬＥＤドライバ回路１００の制御方法の一例について説明する。 Next, an example of a method for controlling the LED driver circuit 100 having the above configuration will be described.
　まず、例えば、ユーザによりメインスイッチＭＳＷがオンに切り替えられることにより、制御部Ｘは、バッテリＢから電力が供給されて動作（起動）する。 First, for example, when the main switch MSW is turned on by the user, the control unit X is supplied with power from the battery B and operates (starts up).
　このメインスイッチＭＳＷがオンすることにより、リレーＲＥがオンする。これにより、バッテリＢからヘッドランプユニット１０１に電力が供給可能な状態になる。このとき、第１、第２のＬＥＤスイッチＬＳ１がオフしているとすると、第１、第２のＬＥＤ回路ＬＣ１、ＬＣ２には、電流が流れない。 When the main switch MSW is turned on, the relay RE is turned on. As a result, power can be supplied from the battery B to the headlamp unit 101. At this time, if the first and second LED switches LS1 are turned off, no current flows through the first and second LED circuits LC1 and LC2.
　このとき、第１の端子電圧は、接地電圧、すなわち、第１の上限値未満になる。さらに、第２の端子電圧は、接地電圧、すなわち、第２の上限値未満となる。 At this time, the first terminal voltage is lower than the ground voltage, that is, the first upper limit value. Furthermore, the second terminal voltage is less than the ground voltage, that is, the second upper limit value.
　そして、制御部Ｘは、第１の端子電圧が予め設定された第１の上限値未満であるので、第１の基準電圧を制御することにより、第１の制御信号により第１のオンデューティ（例えば、１００％のオンデューティ）で第１のスイッチ素子ＳＷ１を制御する。 Since the first terminal voltage is less than the preset first upper limit value, the control unit X controls the first reference voltage to control the first on-duty ( For example, the first switch element SW1 is controlled with an on-duty of 100%.
　さらに、制御部Ｘは、第２の端子電圧が予め設定された第２の上限値未満であるので、第２の基準電圧を制御することにより、第２の制御信号により第３のオンデューティ（例えば、１００％のオンデューティ）で第２のスイッチ素子ＳＷ２を制御する。 Furthermore, since the second terminal voltage is less than the preset second upper limit value, the control unit X controls the second reference voltage, thereby controlling the third on-duty ( For example, the second switch element SW2 is controlled with an on-duty of 100%.
　その後、例えば、ユーザにより第１のＬＥＤスイッチＬＳ１がオンに切り替えられるとする。このとき、第１のスイッチ素子ＳＷ１が第１のオンデューティで制御されているため、第１のＬＥＤ回路ＬＣ１に所定の電流が流れて、ＬＥＤ素子が発光することとなる。 Thereafter, for example, it is assumed that the first LED switch LS1 is turned on by the user. At this time, since the first switch element SW1 is controlled with the first on-duty, a predetermined current flows through the first LED circuit LC1, and the LED element emits light.
　一方、ユーザにより第２のＬＥＤスイッチＬＳ２がオンに切り替えられるとする。このとき、第２のスイッチ素子ＳＷ２が第３のオンデューティで制御されているため、第２のＬＥＤ回路ＬＣ２に所定の電流が流れて、ＬＥＤ素子が発光することとなる。 On the other hand, it is assumed that the second LED switch LS2 is turned on by the user. At this time, since the second switch element SW2 is controlled with the third on-duty, a predetermined current flows through the second LED circuit LC2, and the LED element emits light.
　このように、ＬＥＤドライバ回路１００は、スイッチ切り替えの情報が不要になるので、外部信号が不要になる。また、定電流電源が不要になる。 Thus, since the LED driver circuit 100 does not need switch switching information, an external signal is not required. Moreover, a constant current power supply is not necessary.
　その後、例えば、バッテリ異常時等で、過電圧となった場合、第１の端子電圧は、第１の上限値に達し、第２の端子電圧は、第２の上限値に達することとなる。 After that, for example, when an overvoltage occurs due to a battery abnormality or the like, the first terminal voltage reaches the first upper limit value, and the second terminal voltage reaches the second upper limit value.
　このとき、制御部Ｘは、第１の端子電圧が第１の上限値に達しているので、第１の基準電圧を制御することにより、第１の制御信号により上記第１のオンデューティより小さい第２のオンデューティで第１のスイッチ素子ＳＷ１を制御する。 At this time, since the first terminal voltage has reached the first upper limit value, the control unit X controls the first reference voltage so that the first control signal is smaller than the first on-duty. The first switch element SW1 is controlled with the second on-duty.
　これにより、第１のスイッチ素子ＳＷ１（第１のＭＯＳトランジスタＭ１）に流れる電流が制限されて、第１のスイッチ素子ＳＷ１における発熱が抑制される。 Thereby, the current flowing through the first switch element SW1 (first MOS transistor M1) is limited, and heat generation in the first switch element SW1 is suppressed.
　さらに、制御部Ｘは、第２の端子電圧が第２の上限値に達しているので、第２の基準電圧を制御することにより、第２の制御信号により上記第３のオンデューティより小さい第４のオンデューティで第２のスイッチ素子ＳＷ２を制御する。 Further, since the second terminal voltage has reached the second upper limit value, the control unit X controls the second reference voltage, thereby reducing the second terminal voltage smaller than the third on-duty by the second control signal. The second switch element SW2 is controlled with an on-duty of 4.
　これにより、第２のスイッチ素子ＳＷ２（第２のＭＯＳトランジスタＭ２）に流れる電流が制限されて、第２のスイッチ素子ＳＷ２における発熱が抑制される。 Thereby, the current flowing through the second switch element SW2 (second MOS transistor M2) is limited, and heat generation in the second switch element SW2 is suppressed.
　これにより、ＬＥＤドライバ回路１００は、バッテリ異常時等で、過電圧となった場合に、ＬＥＤ素子の光度は、低下するが、急に消灯するのを抑制しつつ、スイッチ素子（ＭＯＳトランジスタ）の発熱を抑制することができる。 As a result, the LED driver circuit 100 generates heat of the switch element (MOS transistor) while suppressing the sudden turn-off while the light intensity of the LED element decreases when an overvoltage occurs due to a battery abnormality or the like. Can be suppressed.
　また、例えば、第１のＬＥＤ回路ＬＣ１のＬＥＤ素子の何れかがショートすると、バッテリ電圧と第１の端子電圧との第１の電位差が、第１の規定値以下になる。このとき、制御部Ｘは、バッテリ電圧と第１の端子電圧との第１の電位差が、第１の規定値以下であるので、第１の基準電圧を制御することにより、第１のスイッチ素子ＳＷ１のオンデューティを低下させる。 For example, when any one of the LED elements of the first LED circuit LC1 is short-circuited, the first potential difference between the battery voltage and the first terminal voltage becomes equal to or less than the first specified value. At this time, since the first potential difference between the battery voltage and the first terminal voltage is equal to or smaller than the first specified value, the control unit X controls the first reference voltage to thereby control the first switch element. The on-duty of SW1 is reduced.
　また、例えば、第２のＬＥＤ回路ＬＣ２のＬＥＤ素子の何れかがショートすると、バッテリ電圧と第２の端子電圧との第２の電位差が、第２の規定値以下になる。このとき、制御部Ｘは、バッテリ電圧と第２の端子電圧との第２の電位差が、第２の規定値以下であるので、第２の基準電圧を制御することにより、第２のスイッチ素子ＳＷ２のオンデューティを低下させる。 For example, when any of the LED elements of the second LED circuit LC2 is short-circuited, the second potential difference between the battery voltage and the second terminal voltage becomes equal to or less than the second specified value. At this time, since the second potential difference between the battery voltage and the second terminal voltage is equal to or less than the second specified value, the control unit X controls the second reference voltage to thereby control the second switch element. The on-duty of SW2 is reduced.
　これにより、スイッチ素子（ＭＯＳトランジスタ）の発熱を抑制させることができる。 Thereby, heat generation of the switch element (MOS transistor) can be suppressed.
　以降、同様の動作が繰り返される。 Thereafter, the same operation is repeated.
　以上のように、本発明の一態様に係るＬＥＤドライバ回路１００は、第１のＬＥＤ端子ＴＬ１と接地端子ＴＧとの間に接続された第１のスイッチ素子ＳＷ１と、第２のＬＥＤ端子ＴＬ２と接地端子ＴＧとの間に接続された第２のスイッチ素子ＳＷ２と、第１のＬＥＤ端子ＴＬ１の第１の端子電圧を検出する第１の電圧検出回路ＶＤ１と、第２のＬＥＤ端子ＴＬ２の第２の端子電圧を検出する第２の電圧検出回路ＶＤ２と、第１の端子電圧および第２の端子電圧に応じて、第１のスイッチ素子ＳＷ１および第２のスイッチ素子ＳＷ２を制御する制御部Ｘと、を備える。 As described above, the LED driver circuit 100 according to one embodiment of the present invention includes the first switch element SW1 connected between the first LED terminal TL1 and the ground terminal TG, and the second LED terminal TL2. The second switch element SW2 connected between the ground terminal TG, the first voltage detection circuit VD1 for detecting the first terminal voltage of the first LED terminal TL1, and the second of the second LED terminal TL2. A second voltage detection circuit VD2 that detects a terminal voltage of 2 and a control unit X that controls the first switch element SW1 and the second switch element SW2 according to the first terminal voltage and the second terminal voltage And comprising.
　そして、バッテリの正極ＢＰと第１のＬＥＤ端子ＴＬ１との間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチが、第１のＬＥＤ回路ＬＣ１と直列に接続されている。 And the 1st LED switch which can be switched on / off by the user between the positive electrode BP of the battery and the first LED terminal TL1 is connected in series with the first LED circuit LC1.
　そして、制御部Ｘは、第１の端子電圧が予め設定された第１の上限値未満の場合には、第１のオンデューティで第１のスイッチ素子ＳＷ１を制御し、第１の端子電圧が第１の上限値に達した場合には、第１のオンデューティより小さい第２のオンデューティで第１のスイッチ素子ＳＷ１を制御し、第２の端子電圧が予め設定された第２の上限値未満の場合には、第３のオンデューティで第２のスイッチ素子ＳＷ２を制御し、第２の端子電圧が第２の上限値に達した場合には、第３のオンデューティより小さい第４のオンデューティで第２のスイッチ素子ＳＷ２を制御する。 When the first terminal voltage is less than the preset first upper limit value, the control unit X controls the first switch element SW1 with the first on-duty so that the first terminal voltage is When the first upper limit value is reached, the first switch element SW1 is controlled with a second on-duty smaller than the first on-duty, and the second terminal voltage is set to a second upper limit value set in advance. If less than the third on-duty, the second switch element SW2 is controlled, and if the second terminal voltage reaches the second upper limit, the fourth on-duty is smaller than the third on-duty. The second switch element SW2 is controlled with on-duty.
　これにより、本発明に係るＬＥＤドライバ回路１００は、スイッチ切り替えの情報が不要になるので、外部信号が不要になる。また、定電流電源が不要になる。 Thereby, the LED driver circuit 100 according to the present invention does not require information on switch switching, and thus no external signal is required. Moreover, a constant current power supply is not necessary.
　すなわち、ＬＥＤドライバ回路１００の端子、配線等を削減することができる。 That is, the terminals and wiring of the LED driver circuit 100 can be reduced.
　さらに、本発明に係るＬＥＤドライバ回路１００は、バッテリ異常時等で、過電圧となった場合に、ＬＥＤ素子の光度は、低下するが、急に消灯するのを抑制しつつ、ＭＯＳトランジスタの発熱を抑制することができる。 Furthermore, the LED driver circuit 100 according to the present invention reduces the light intensity of the LED element when an overvoltage occurs due to a battery abnormality or the like, but suppresses the sudden turn-off and suppresses heat generation of the MOS transistor. Can be suppressed.
　さらに、制御部Ｘは、バッテリ電圧と第１の端子電圧との第１の電位差が、第１の規定値以下である場合には、第１のスイッチ素子ＳＷ１のオンデューティを低下させ、また、バッテリ電圧と第２の端子電圧との第２の電位差が、第２の規定値以下である場合には、第２のスイッチ素子ＳＷ２のオンデューティを低下させる。 Further, the control unit X reduces the on-duty of the first switch element SW1 when the first potential difference between the battery voltage and the first terminal voltage is equal to or less than the first specified value, and When the second potential difference between the battery voltage and the second terminal voltage is equal to or less than the second specified value, the on-duty of the second switch element SW2 is reduced.
　これにより、バッテリ電圧とＬＥＤ端子の電圧との電位差が規定値以下の場合（すなわち、ＬＥＤ素子の少なくともいずれかがショートした場合）に、スイッチ素子（ＭＯＳトランジスタ）のオンデューティを低下させて、スイッチ素子（ＭＯＳトランジスタ）の発熱を抑制させることができる。 This reduces the on-duty of the switch element (MOS transistor) when the potential difference between the battery voltage and the LED terminal voltage is equal to or less than a specified value (that is, when at least one of the LED elements is short-circuited). Heat generation of the element (MOS transistor) can be suppressed.
　さらに、制御部Ｘは、第１の端子電圧が予め設定された第１の判断値以下である場合には、第１のＬＥＤ回路ＬＣ１のＬＥＤ素子に断線が発生していると判断し、第２の端子電圧が予め設定された第２の判断値以下である場合には、第２のＬＥＤ回路ＬＣ２のＬＥＤ素子に断線が発生していると判断する。 Further, when the first terminal voltage is equal to or lower than the first determination value set in advance, the control unit X determines that a disconnection has occurred in the LED element of the first LED circuit LC1, and When the terminal voltage of 2 is equal to or lower than the second determination value set in advance, it is determined that a disconnection has occurred in the LED element of the second LED circuit LC2.
　これにより、Ｌｏ、ＨｉのＬＥＤ端子の電圧がゼロ（判断値以下）である場合には、ＨｉｇｈビームまたはＬｏｗビームのＬＥＤ素子に、断線が発生したと判断できる。 Thereby, when the voltages of the Lo and Hi LED terminals are zero (below the judgment value), it can be determined that a disconnection has occurred in the LED element of the High beam or the Low beam.
　このように、ＬＥＤドライバ回路１００は、例えば、２輪車のヘッドランプにおいて、ＨｉｇｈビームまたはＬｏｗビームの断線を検出することができる。 Thus, the LED driver circuit 100 can detect a disconnection of a high beam or a low beam in a headlamp of a two-wheeled vehicle, for example.
　本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれると同様に、特許請求の範囲に記載された発明とその均等の範囲に含まれるものである。 Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

Claims (10)

  1. 　１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリの正極にアノード側が接続された第１のＬＥＤ回路と、１つ又は直列に接続された複数のＬＥＤ素子を有し且つ前記バッテリの正極にアノード側が接続された第２のＬＥＤ回路と、を駆動するＬＥＤドライバ回路であって、
    　前記第１のＬＥＤ回路のカソード側が接続される第１のＬＥＤ端子と、
    　前記第２のＬＥＤ回路のカソード側が接続される第２のＬＥＤ端子と、
    　前記バッテリの負極に接続される接地端子と、
    　前記第１のＬＥＤ端子と前記接地端子との間に接続された第１のスイッチ素子と、
    　前記第２のＬＥＤ端子と前記接地端子との間に接続された第２のスイッチ素子と、
    　前記第１のＬＥＤ端子の第１の端子電圧を検出する第１の電圧検出回路と、
    　前記第２のＬＥＤ端子の第２の端子電圧を検出する第２の電圧検出回路と、
    　前記第１の端子電圧および前記第２の端子電圧に応じて、前記第１のスイッチ素子および前記第２のスイッチ素子を制御する制御部と、を備え、
    　前記バッテリの正極と前記第１のＬＥＤ端子との間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチが、前記第１のＬＥＤ回路と直列に接続されており、
    　前記制御部は、
    　前記第１の端子電圧が予め設定された第１の上限値未満の場合には、第１のオンデューティで前記第１のスイッチ素子を制御し、
    　前記第１の端子電圧が前記第１の上限値に達した場合には、前記第１のオンデューティより小さい第２のオンデューティで前記第１のスイッチ素子を制御し、
    　前記第２の端子電圧が予め設定された第２の上限値未満の場合には、第３のオンデューティで前記第２のスイッチ素子を制御し、
    　前記第２の端子電圧が前記第２の上限値に達した場合には、前記第３のオンデューティより小さい第４のオンデューティで前記第２のスイッチ素子を制御する
    　ことを特徴とするＬＥＤドライバ回路。     A first LED circuit having one or a plurality of LED elements connected in series and having an anode side connected to the positive electrode of the battery, and one or a plurality of LED elements connected in series, and the battery A second LED circuit having an anode connected to the positive electrode of the LED driver circuit, and an LED driver circuit for driving the second LED circuit,
    A first LED terminal to which a cathode side of the first LED circuit is connected;
    A second LED terminal to which the cathode side of the second LED circuit is connected;
    A ground terminal connected to the negative electrode of the battery;
    A first switch element connected between the first LED terminal and the ground terminal;
    A second switch element connected between the second LED terminal and the ground terminal;
    A first voltage detection circuit for detecting a first terminal voltage of the first LED terminal;
    A second voltage detection circuit for detecting a second terminal voltage of the second LED terminal;
    A control unit that controls the first switch element and the second switch element according to the first terminal voltage and the second terminal voltage, and
    A first LED switch that can be switched on / off by a user between the positive electrode of the battery and the first LED terminal is connected in series with the first LED circuit;
    The controller is
    When the first terminal voltage is less than a preset first upper limit value, the first switch element is controlled with a first on-duty;
    When the first terminal voltage reaches the first upper limit value, the first switch element is controlled with a second on-duty smaller than the first on-duty;
    When the second terminal voltage is less than a preset second upper limit value, the second switch element is controlled with a third on-duty;
    When the second terminal voltage reaches the second upper limit value, the second switch element is controlled with a fourth on-duty smaller than the third on-duty. circuit.
  2. 　前記バッテリのバッテリ電圧を検出するバッテリ電圧検出回路をさらに備え、
    　前記制御部は、
    　前記バッテリ電圧と前記第１の端子電圧との第１の電位差が、第１の規定値以下である場合には、前記第１のスイッチ素子のオンデューティを低下させ、
    　また、前記バッテリ電圧と前記第２の端子電圧との第２の電位差が、第２の規定値以下である場合には、前記第２のスイッチ素子のオンデューティを低下させる
    　ことを特徴とする請求項１に記載のＬＥＤドライバ回路。     A battery voltage detection circuit for detecting a battery voltage of the battery;
    The controller is
    When the first potential difference between the battery voltage and the first terminal voltage is not more than a first specified value, the on-duty of the first switch element is reduced,
    The on-duty of the second switch element is lowered when a second potential difference between the battery voltage and the second terminal voltage is equal to or less than a second specified value. Item 2. The LED driver circuit according to Item 1.
  3. 　前記制御部は、
    　前記第１の電位差が、前記第１の規定値よりも低い第３の規定値以下である場合には、前記第１のスイッチ素子をオフし、
    　前記第２の電位差が、前記第２の規定値よりも低い第４の規定値以下である場合には、前記第２のスイッチ素子をオフする
    　ことを特徴とする請求項２に記載のＬＥＤドライバ回路。     The controller is
    When the first potential difference is not more than a third specified value lower than the first specified value, the first switch element is turned off,
    3. The LED driver according to claim 2, wherein the second switch element is turned off when the second potential difference is equal to or lower than a fourth specified value lower than the second specified value. circuit.
  4. 　前記制御部は、
    　前記第１の端子電圧が予め設定された第１の判断値以下である場合には、前記第１のＬＥＤ回路のＬＥＤ素子に断線が発生していると判断し、
    　前記第２の端子電圧が予め設定された第２の判断値以下である場合には、前記第２のＬＥＤ回路のＬＥＤ素子に断線が発生していると判断する
    　ことを特徴とする請求項１に記載のＬＥＤドライバ回路。     The controller is
    When the first terminal voltage is equal to or lower than a first determination value set in advance, it is determined that a disconnection has occurred in the LED element of the first LED circuit;
    2. When the second terminal voltage is equal to or lower than a second determination value set in advance, it is determined that a disconnection has occurred in the LED element of the second LED circuit. LED driver circuit according to claim 1.
  5. 　前記第１の判断値および前記第２の判断値は、接地電圧であることを特徴とする請求項４に記載のＬＥＤドライバ回路。 The LED driver circuit according to claim 4, wherein the first judgment value and the second judgment value are ground voltages.
  6. 　前記第１および第３のオンデューティは、１００％のオンデューティであることを特徴とする請求項１に記載のＬＥＤドライバ回路。 The LED driver circuit according to claim 1, wherein the first and third on-duties are 100% on-duty.
  7. 　前記バッテリの正極と前記第２のＬＥＤ端子との間で、ユーザによりオン／オフが切り替え可能な第２のＬＥＤスイッチが前記第２のＬＥＤ回路と直列に接続されている
    　ことを特徴とする請求項１に記載のＬＥＤドライバ回路。     A second LED switch that can be switched on / off by a user is connected in series with the second LED circuit between a positive electrode of the battery and the second LED terminal. Item 2. The LED driver circuit according to Item 1.
  8. 　リレーの一端が前記バッテリの正極に接続され、前記リレーの他端が前記第１のＬＥＤ回路および前記第２のＬＥＤ回路のアノード側に接続され、
    　前記リレーの他端と前記バッテリの負極との間に負荷が接続され、
    　前記第１のＬＥＤ回路および前記第２のＬＥＤ回路は、２輪車のヘッドランプのＬＥＤであり、
    　前記負荷は、前記２輪車のエンジンの点火装置であることを特徴とする請求項１に記載のＬＥＤドライバ回路。     One end of the relay is connected to the positive electrode of the battery, the other end of the relay is connected to the anode side of the first LED circuit and the second LED circuit,
    A load is connected between the other end of the relay and the negative electrode of the battery,
    The first LED circuit and the second LED circuit are LEDs of a headlamp of a motorcycle,
    The LED driver circuit according to claim 1, wherein the load is an ignition device for an engine of the two-wheeled vehicle.
  9. 　前記第１のスイッチ素子は、
    　前記第１のＬＥＤ端子と前記接地端子との間に接続され、前記制御部によりゲート電圧が制御される第１のＭＯＳトランジスタであり、
    　前記第２のスイッチ素子は、
    　前記第２のＬＥＤ端子と前記接地端子との間に接続され、前記制御部によりゲート電圧が制御される第２のＭＯＳトランジスタであり、
    　前記ＬＥＤドライバ回路は、
    　前記制御部により制御される第１の基準電圧を出力する第１の基準電圧回路と、
    　前記第１のスイッチ素子と前記接地端子との間に接続された第１の検出用抵抗と、
    　前記第１の基準電圧と、前記第１のスイッチ素子と前記第１の検出用抵抗との間の第１の検出電圧とを比較し、前記第１の基準電圧と前記第１の検出電圧とが等しくなるように、前記第１のＭＯＳトランジスタを動作させる第１の制御信号を出力する第１のコンパレータと、
    　前記第１のコンパレータの出力と前記第１のＭＯＳトランジスタのゲートとの間に接続された第１の制御用抵抗と、
    　前記制御部により制御される第２の基準電圧を出力する第２の基準電圧回路と、
    　前記第２のスイッチ素子と前記接地端子との間に接続された第２の検出用抵抗と、
    　前記第２の基準電圧と、前記第２のスイッチ素子と前記第２の検出用抵抗との間の第２の検出電圧とを比較し、前記第２の基準電圧と前記第２の検出電圧とが等しくなるように、前記第２のＭＯＳトランジスタを動作させる第２の制御信号を出力する第２のコンパレータと、
    　前記第２のコンパレータの出力と前記第２のＭＯＳトランジスタのゲートとの間に接続された第２の制御用抵抗と、をさらに備え、
    　前記制御部は、
    　前記第１の端子電圧が前記第１の上限値未満の場合には、前記第１の制御信号により前記第１のオンデューティで前記第１のスイッチ素子が動作するように、前記第１の基準電圧を制御し、
    　前記第１の端子電圧が前記第１の上限値に達した場合には、前記第１の制御信号により前記第２のオンデューティで前記第１のスイッチ素子が動作するように、前記第１の基準電圧を制御し、
    　前記第２の端子電圧が予め設定された第２の上限値未満の場合には、前記第２の制御信号により前記第３のオンデューティで前記第２のスイッチ素子が動作するように、前記第２の基準電圧を制御し、
    　前記第２の端子電圧が前記第２の上限値に達した場合には、前記第２の制御信号により前記第４のオンデューティで前記第２のスイッチ素子が動作するように、前記第２の基準電圧を制御する
    　ことを特徴とする請求項１に記載のＬＥＤドライバ回路。     The first switch element includes:
    A first MOS transistor connected between the first LED terminal and the ground terminal, the gate voltage of which is controlled by the control unit;
    The second switch element is
    A second MOS transistor connected between the second LED terminal and the ground terminal, the gate voltage of which is controlled by the control unit;
    The LED driver circuit is:
    A first reference voltage circuit that outputs a first reference voltage controlled by the control unit;
    A first detection resistor connected between the first switch element and the ground terminal;
    The first reference voltage is compared with the first detection voltage between the first switch element and the first detection resistor, and the first reference voltage and the first detection voltage are compared. A first comparator that outputs a first control signal for operating the first MOS transistor such that
    A first control resistor connected between the output of the first comparator and the gate of the first MOS transistor;
    A second reference voltage circuit that outputs a second reference voltage controlled by the control unit;
    A second detection resistor connected between the second switch element and the ground terminal;
    The second reference voltage is compared with a second detection voltage between the second switch element and the second detection resistor, and the second reference voltage and the second detection voltage are compared. A second comparator that outputs a second control signal for operating the second MOS transistor so that
    A second control resistor connected between the output of the second comparator and the gate of the second MOS transistor;
    The controller is
    When the first terminal voltage is less than the first upper limit value, the first reference is set so that the first switch element operates at the first on-duty by the first control signal. Control the voltage,
    When the first terminal voltage reaches the first upper limit value, the first switch element is operated with the second on-duty by the first control signal. Control the reference voltage,
    When the second terminal voltage is less than a preset second upper limit value, the second switch element is operated with the third on-duty by the second control signal. Control the reference voltage of 2,
    When the second terminal voltage reaches the second upper limit value, the second switch element is operated by the second control signal at the fourth on-duty by the second control signal. The LED driver circuit according to claim 1, wherein a reference voltage is controlled.
  10. 　１つ又は直列に接続された複数のＬＥＤ素子を有し且つバッテリの正極にアノード側が接続された第１のＬＥＤ回路と、１つ又は直列に接続された複数のＬＥＤ素子を有し且つ前記バッテリの正極にアノード側が接続された第２のＬＥＤ回路と、を駆動するＬＥＤドライバ回路であって、前記第１のＬＥＤ回路のカソード側が接続される第１のＬＥＤ端子と、前記第２のＬＥＤ回路のカソード側が接続される第２のＬＥＤ端子と、前記バッテリの負極に接続される接地端子と、前記第１のＬＥＤ端子と前記接地端子との間に接続された第１のスイッチ素子と、前記第２のＬＥＤ端子と前記接地端子との間に接続された第２のスイッチ素子と、前記第１のＬＥＤ端子の第１の端子電圧を検出する第１の電圧検出回路と、前記第２のＬＥＤ端子の第２の端子電圧を検出する第２の電圧検出回路と、前記第１の端子電圧および前記第２の端子電圧に応じて、前記第１のスイッチ素子および前記第２のスイッチ素子を制御する制御部と、を備えたＬＥＤドライバ回路の制御方法において、
    　前記バッテリの正極と前記第１のＬＥＤ端子との間で、ユーザによりオン／オフが切り替え可能な第１のＬＥＤスイッチが、前記第１のＬＥＤ回路と直列に接続されており、
    　前記制御部は、
    　前記第１の端子電圧が予め設定された第１の上限値未満の場合には、第１のオンデューティで前記第１のスイッチ素子を制御し、
    　前記第１の端子電圧が前記第１の上限値に達した場合には、前記第１のオンデューティより小さい第２のオンデューティで前記第１のスイッチ素子を制御し、
    　前記第２の端子電圧が予め設定された第２の上限値未満の場合には、第３のオンデューティで前記第２のスイッチ素子を制御し、
    　前記第２の端子電圧が前記第２の上限値に達した場合には、前記第３のオンデューティより小さい第４のオンデューティで前記第２のスイッチ素子を制御する
    　ことを特徴とするＬＥＤドライバ回路の制御方法。　     A first LED circuit having one or a plurality of LED elements connected in series and having an anode side connected to the positive electrode of the battery, and one or a plurality of LED elements connected in series, and the battery A second LED circuit whose anode side is connected to the positive electrode of the first LED circuit, the first LED terminal to which the cathode side of the first LED circuit is connected, and the second LED circuit A second LED terminal connected to the cathode side of the battery, a ground terminal connected to the negative electrode of the battery, a first switch element connected between the first LED terminal and the ground terminal, A second switch element connected between a second LED terminal and the ground terminal; a first voltage detection circuit for detecting a first terminal voltage of the first LED terminal; LED terminal A second voltage detection circuit for detecting a terminal voltage of the second, and a control unit for controlling the first switch element and the second switch element according to the first terminal voltage and the second terminal voltage And a method of controlling an LED driver circuit comprising:
    A first LED switch that can be switched on / off by a user between the positive electrode of the battery and the first LED terminal is connected in series with the first LED circuit;
    The controller is
    When the first terminal voltage is less than a preset first upper limit value, the first switch element is controlled with a first on-duty;
    When the first terminal voltage reaches the first upper limit value, the first switch element is controlled with a second on-duty smaller than the first on-duty;
    When the second terminal voltage is less than a preset second upper limit value, the second switch element is controlled with a third on-duty;
    When the second terminal voltage reaches the second upper limit value, the second switch element is controlled with a fourth on-duty smaller than the third on-duty. Circuit control method.
PCT/JP2013/083706 2013-12-17 2013-12-17 Led driver circuit and method for controlling led driver circuit WO2015092864A1 (en)

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