JP2017135086A - Lighting device of solid light-emitting element, lighting fixture, and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an excessive current flowing to a solid light-emitting element.SOLUTION: A lighting device 1 comprises a power supply 10, a switch 11, and a charge extraction part 12. The switch 11 has: one or more switch elements Q3 to Q6; and a drive circuit 110 for turning on/off the one or more switch elements Q3 to Q6. The charge extraction part 12 has a series circuit configured by a resistor 120 and an extraction switch element Q2. The series circuit is electrically connected in parallel to a smoothing capacitor C1 and the switch 11. The charge extraction part 12 turns on the extraction switch element Q2 before the switch elements Q3 to Q6 of the switch 11 are turned on so as to extract electric charge in the smoothing capacitor C1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid state light emitting device lighting device, a lamp, and a vehicle.

  As a conventional example of a solid state light emitting device lighting device, an LED lighting device described in Patent Document 1 is illustrated. This conventional example includes a power supply unit, a control unit, a delay circuit, a constant current circuit, and the like. The power supply unit is a DC / DC converter, and has a smoothing capacitor between output terminals. An LED light source is connected between both ends of the smoothing capacitor. The LED light source includes an LED block that constitutes a traveling lamp (high beam) of a headlamp mounted on the vehicle, and an LED block that constitutes a passing lamp (low beam). The LED block of the passing lamp is short-circuited when one of the switching elements is turned on, and is made conductive when turned off. Further, the LED block of the traveling light is short-circuited when the other switching element is turned on, and is made conductive when turned off. These two switching elements are turned on and off by the control unit. The constant current circuit has two transistors, and turns each switching element on by passing a constant current to the gate resistances of the two switching elements via the two transistors. The delay circuit slowly increases or decreases the gate voltages of the switching elements Q1 and Q2 by slowing the change in the voltage applied to the base terminals of the two transistors of the constant current circuit.

  In the above conventional example, the switching operation between the terminals of the LED block by the switching element from the open circuit to the short circuit and the switching operation from the short circuit to the open circuit are made slower than the response operation of the output power of the power supply unit. In the above conventional example, when the terminals of the LED block are short-circuited and opened, an excessive current is prevented from flowing through the LED block.

JP 2012-28184 A

  However, in the above conventional example, it is difficult to accurately match the switching operation of the switching element and the response operation of the output power of the power supply unit due to the influence of the temperature characteristics of the capacitors and resistors constituting the delay circuit. For this reason, the conventional example may not prevent an excessive current from flowing through the LED block.

  An object of the present invention is to provide a solid-state light-emitting element lighting device, a lamp, and a vehicle that can reduce excessive current flowing in the solid-state light-emitting element.

  A solid state light emitting device lighting device according to an aspect of the present invention includes a power supply unit, a switching unit, and a charge extraction unit. The power supply unit includes a voltage conversion circuit that converts an input voltage into a DC output voltage, and a control unit that controls the voltage conversion circuit. The voltage conversion circuit is a DC / DC converter having a smoothing capacitor between output terminals. The control unit controls the voltage conversion circuit so that the output current of the voltage conversion circuit is made constant. The switching unit includes one or more switch elements and a drive circuit that turns on or off the one or more switch elements, and is electrically connected in parallel to the smoothing capacitor. Each of the one or more switch elements is electrically connected in parallel with one solid light emitting element or a series circuit of the plurality of solid light emitting elements. The charge extraction unit has a series circuit of a resistor and an extraction switch element. The series circuit is electrically connected in parallel with the smoothing capacitor. The charge extraction unit is configured to extract the charge of the smoothing capacitor by turning on the extraction switch element before the switch element of the switching unit is turned on.

  A lamp according to an aspect of the present invention houses the solid-state light-emitting element lighting device, one or more solid-state light-emitting elements that are turned on by the solid-state light-emitting element lighting device, and the one or more solid-state light-emitting elements. And a lamp body.

  A vehicle according to an aspect of the present invention includes the lamp and a vehicle body on which the lamp is mounted.

  The solid-state light-emitting element lighting device, the lamp, and the vehicle of the present invention have an effect that it is possible to reduce an excessive current flowing through the solid-state light-emitting element.

FIG. 1 is a circuit configuration diagram of a solid state light emitting device lighting device according to an embodiment of the present invention. FIG. 2 is a circuit configuration diagram of a switching unit in the solid-state light emitting device lighting device. FIG. 3 is a timing chart for explaining the operation of the solid-state light-emitting element lighting device. FIG. 4 is a timing chart for explaining another operation of the solid state light emitting device lighting device of the above. FIG. 5 is a circuit diagram showing another configuration of the charge extracting unit in the solid-state light emitting device lighting device. FIG. 6 is a side sectional view of a lamp according to an embodiment of the present invention. FIG. 7 is a plan sectional view of the lamp. FIG. 8 is a perspective view of a vehicle according to an embodiment of the present invention.

  A solid state light emitting device lighting device, a lamp, and a vehicle according to an embodiment of the present invention will be described in detail with reference to the drawings. The embodiment described below relates to a solid-state light-emitting element lighting device that lights a solid-state light-emitting element such as a light-emitting diode, and a lamp using the solid-state light-emitting element lighting device. Furthermore, the embodiment described below relates to a vehicle using a lamp as a headlamp. The configurations described in the following embodiments are merely examples of the present invention. The present invention is not limited to the following embodiments, and various modifications can be made according to the design and the like as long as they do not depart from the technical idea of the present invention.

  As shown in FIG. 1, a solid-state light-emitting element lighting device (hereinafter abbreviated as a lighting device) 1 according to this embodiment includes a power supply unit 10, a switching unit 11, a charge extraction unit 12, and a control unit 14. ing. The lighting device 1 is lit by supplying DC power to the light emitting unit 13. The light emitting unit 13 has four solid light emitting elements. However, the number of solid state light emitting elements is not limited to four, and may be one, two, three, or five or more. The solid light emitting element is preferably, for example, an LED (light emitting diode). The light emitting unit 13 is composed of a series circuit of four LEDs, a first LED 13A, a second LED 13B, a third LED 13C, and a fourth LED 13D. However, the solid state light emitting device is not limited to the LED, and may be, for example, an organic electroluminescence device or a laser diode.

  In the light emitting unit 13, the cathode of the first LED 13A is electrically connected to the anode of the second LED 13B, and the cathode of the second LED 13B is electrically connected to the anode of the third LED 13C. Furthermore, the cathode of the third LED 13C is electrically connected to the anode of the fourth LED 13D. In the following description, the anode of the first LED 13A may be referred to as the positive electrode of the light emitting unit 13, and the cathode of the fourth LED 13D may be referred to as the negative electrode of the light emitting unit 13.

  As shown in FIG. 1, the power supply unit 10 includes a voltage conversion circuit 100 and a first control circuit 140. The voltage conversion circuit 100 converts the input voltage into a DC output voltage V1. The input voltage is preferably supplied from, for example, a DC power source 2 that is a battery mounted on the vehicle. The voltage conversion circuit 100 is a flyback DC / DC converter. The voltage conversion circuit 100 includes a first switching element Q1, a transformer T1, a diode D1, a smoothing capacitor C1, and the like as constituent elements. The transformer T1 has a primary winding N1 and a secondary winding N2. A terminal on the winding start side of the primary winding N1 is electrically connected to the positive electrode of the DC power supply 2 via the power switch 3. The terminal on the winding end side of the primary winding N1 is electrically connected to the drain of the first switching element Q1. The first switching element Q1 is an n-channel enhancement type field effect transistor. The source of the first switching element Q1 is electrically connected to the negative electrode of the DC power supply 2 and the ground. A terminal on the winding start side of the secondary winding N2 of the transformer T1 is electrically connected to one end of the smoothing capacitor C1 and the ground. The terminal on the winding end side of the secondary winding N2 is electrically connected to the anode of the diode D1. The cathode of the diode D1 is electrically connected to the other end of the smoothing capacitor C1.

  The first control circuit 140 preferably includes an oscillator 143, a first comparator 144, a second comparator 145, an error amplifier 146, a constant current source 147, a transistor Q7, a resistor R2, and the like. The oscillator 143 is configured by an RS flip-flop circuit. The output terminal Q of the oscillator 143 is electrically connected to the gate of the first switching element Q1 of the voltage conversion circuit 100. The set terminal S of the oscillator 143 is electrically connected to the output terminal of the first comparator 144. The reset terminal R of the oscillator 143 is electrically connected to the output terminal of the second comparator 145. The first reference voltage Vr 1 is input to the positive input terminal of the first comparator 144. The second detection voltage Vx2 proportional to the magnitude of the secondary current flowing through the secondary winding N2 of the transformer T1 is input to the negative input terminal of the first comparator 144. That is, the first comparator 144 compares the second detection voltage Vx2 with the first reference voltage Vr1, and sets the voltage at the output terminal to a high level when the second detection voltage Vx2 is lower than the first reference voltage Vr1. The first comparator 144 sets the voltage at the output terminal to a low level when the second detection voltage Vx2 is equal to or higher than the first reference voltage Vr1. Therefore, when the voltage at the output terminal of the first comparator 144 rises to a high level, the oscillator 143 outputs the high-level drive signal VG1 from the output terminal Q to the gate of the first switching element Q1 to output the first switching element Q1. Turn on.

  The negative input terminal of the second comparator 145 is electrically connected to the connection point between the emitter of the transistor Q7 and the constant current source 147. The first detection voltage Vx1 proportional to the magnitude of the primary current flowing in the primary winding N1 of the transformer T1 is input to the positive input terminal of the second comparator 145. The transistor Q7 is a pnp bipolar transistor. The base of the transistor Q7 is electrically connected to the output terminal of the error amplifier 146. The collector of the transistor Q7 is electrically connected to the ground via the resistor R2. The second reference voltage Vr2 is input to the positive input terminal of the error amplifier 146. The third detection voltage Vx3, which is the voltage across the detection resistor R1, is input to the negative input terminal of the error amplifier 146. The detection resistor R1 is electrically connected to the output terminal on the negative electrode side of the voltage conversion circuit 100, specifically, one end on the low potential side of the smoothing capacitor C1. Therefore, the third detection voltage Vx3 is a DC voltage proportional to the output current I1 supplied from the power supply unit 10 to the light emitting unit 13.

  The error amplifier 146 amplifies the difference (error) between the third detection voltage Vx3 and the second reference voltage Vr2, and outputs the amplified difference to the base of the transistor Q7. That is, the value of the current flowing from the constant current source 147 to the resistor R2 via the transistor Q7 is a value proportional to the difference between the third detection voltage Vx3 and the second reference voltage Vr2. Therefore, the command voltage Vy proportional to the difference between the third detection voltage Vx3 and the second reference voltage Vr2 is input to the negative input terminal of the second comparator 145.

  The second comparator 145 compares the first detection voltage Vx1 and the command voltage Vy, and sets the voltage at the output terminal to a high level when the first detection voltage Vx1 is equal to or higher than the command voltage Vy. The second comparator 145 sets the voltage at the output terminal to a low level when the first detection voltage Vx1 is less than the command voltage Vy. Therefore, when the voltage at the output terminal of the second comparator 145 rises to the high level, the oscillator 143 drops the voltage at the output terminal Q to the low level, and the high level drive signal VG1 to the gate of the first switching element Q1. Is stopped and the first switching element Q1 is turned off.

  The first control circuit 140 detects the output current I1 supplied to the light emitting unit 13, and performs the first switching of the voltage conversion circuit 100 so that the magnitude of the output current I1 matches the target value indicated by the command voltage Vy. The element Q1 is on / off controlled. However, the second reference voltage Vr2 can be adjusted by a second control circuit 141 described later.

  The switching unit 11 preferably includes four switch elements Q3, Q4, Q5, and Q6 and a drive circuit 110 that individually turns on and off the four switch elements Q3 to Q6. The four switch elements Q3 to Q6 are all n-channel enhancement type field effect transistors. The drain of the first switch element Q <b> 3 is electrically connected to the positive electrode of the light emitting unit 13 and the output terminal on the positive electrode side of the power supply unit 10. The source of the first switch element Q3 is electrically connected to the cathode of the first LED 13A. The drain of the second switch element Q4 is electrically connected to the source of the first switch element Q3 and the anode of the second LED 13B. The source of the second switch element Q4 is electrically connected to the cathode of the second LED 13B. The drain of the third switch element Q5 is electrically connected to the source of the second switch element Q4 and the anode of the third LED 13C. The source of the third switch element Q5 is electrically connected to the cathode of the third LED 13C. The drain of the fourth switch element Q6 is electrically connected to the source of the third switch element Q5 and the anode of the fourth LED 13D. The source of the fourth switch element Q6 is electrically connected to the negative electrode of the light emitting unit 13 and the ground. That is, when the first switch element Q3 is turned on, the output current I1 of the power supply unit 10 does not flow to the first LED 13A, so the first LED 13A is turned off, and when the first switch element Q3 is turned off, the output is performed. Since the current I1 flows, the first LED 13A is turned on. Similarly, when the second switch element Q4 is on, the output current I1 does not flow, so the second LED 13B is turned off, and when the second switch element Q4 is off, the output current I1 flows, so 2LED 13B lights up. When the third switch element Q5 is on, the output current I1 does not flow, so the third LED 13C is turned off. When the third switch element Q5 is off, the output current I1 flows, so the third LED 13C Light. When the fourth switch element Q6 is on, the output current I1 does not flow, so the fourth LED 13D is turned off. When the fourth switch element Q6 is off, the output current I1 flows, so the fourth LED 13D Light.

  As shown in FIG. 2, the drive circuit 110 includes a drive signal generator 111, four level shift circuits 112A to 112D, and four driver circuits 113A to 113D. The drive signal generator 111 has first to fourth output ports, and outputs a high-level drive signal from each of the first to fourth output ports. The drive signal generator 111 outputs drive signals from one to four output ports instructed by the second control circuit 141 among the first to fourth output ports.

  The first level shift circuit 112A shifts the voltage level of the drive signal output from the first output port and outputs it to the first driver circuit 113A. The second level shift circuit 112B shifts the voltage level of the drive signal output from the second output port and outputs it to the second driver circuit 113B. The third level shift circuit 112C shifts the voltage level of the drive signal output from the third output port and outputs it to the third driver circuit 113C. The fourth level shift circuit 112D shifts the voltage level of the drive signal output from the fourth output port and outputs it to the fourth driver circuit 113D. However, the first to fourth level shift circuits 112A to 112D operate with power supplied from the control power supply 114.

  The first driver circuit 113A amplifies the drive signal input from the first level shift circuit 112A, and applies the amplified drive signal VG3 to the gate of the first switch element Q3. The first switch element Q3 is turned on when the drive signal VG3 is applied to the gate, and turned off when the drive signal VG3 is not applied to the gate. The second driver circuit 113B amplifies the drive signal input from the second level shift circuit 112B, and applies the amplified drive signal VG4 to the gate of the second switch element Q4. The second switch element Q4 is turned on when the drive signal VG4 is applied to the gate, and turned off when the drive signal VG4 is not applied to the gate. The third driver circuit 113C amplifies the drive signal input from the third level shift circuit 112C, and applies the amplified drive signal VG5 to the gate of the third switch element Q5. The third switch element Q5 is turned on when the drive signal VG5 is applied to the gate, and is turned off when the drive signal VG5 is not applied to the gate. The fourth driver circuit 113D amplifies the drive signal input from the fourth level shift circuit 112D, and applies the amplified drive signal VG6 to the gate of the fourth switch element Q6. The fourth switch element Q6 is turned on when the drive signal VG6 is applied to the gate, and is turned off when the drive signal VG6 is not applied to the gate. However, the first to fourth driver circuits 113A to 113D operate with power supplied from the control power source 114. The number of level shift circuits 112 and driver circuits 113 is not limited to four, and may be one, two, three, or five or more depending on the number of solid state light emitting elements of the light emitting unit 13.

  As shown in FIG. 1, the charge extraction unit 12 includes a resistor 120 and an extraction switch element Q2. The drawing switch element Q2 is an n-channel enhancement type field effect transistor. The drain of the drawing switch element Q2 is electrically connected to the output terminal on the high potential side of the power supply unit 10 via the resistor 120. The source of the drawing switch element Q2 is electrically connected to the ground and the detection resistor R1. That is, the charge extracting unit 12 is electrically connected in parallel with the smoothing capacitor C1 of the power supply unit 10. The charge extraction unit 12 is configured to extract the charge of the smoothing capacitor C1 through the resistor 120 by turning on the extraction switch element Q2.

  The second control circuit 141 is preferably composed of, for example, a microcontroller. The second control circuit 141 can receive a control command from an external device such as an electronic control unit (Electronic Control Unit) mounted on the vehicle via the communication interface unit 15. More specifically, the communication interface unit 15 communicates with the electronic control unit using a multiple communication protocol called LIN (Local Interconnect Network). Furthermore, the communication interface unit 15 also communicates with a serial communication device (UART <Universal Asynchronous Receiver / Transmitter>) mounted on a microcontroller configuring the second control circuit 141.

  The control command includes, for example, a first control command for instructing switching of turning on / off of each of the four LEDs 13A to 13D, a second control command for instructing a target value of the output current I1, and the like. When the second control circuit 141 receives the first control command, the control signal for turning off the switch elements Q3 to Q6 corresponding to the LEDs 13A to 13D instructed to be turned on by the first control command is sent to the drive circuit 110. Output. Further, when the second control circuit 141 receives the first control command, the drive circuit sends a control signal for turning on the switch elements Q3 to Q6 corresponding to the LEDs 13A to 13D instructed to be turned off by the first control command. To 110. Further, when receiving the second control command, the second control circuit 141 adjusts the voltage value of the second reference voltage Vr2 of the first control circuit 140 according to the target value instructed by the second control command.

  The second control circuit 141 controls the operation of the charge extracting unit 12. That is, the second control circuit 141 outputs the drive signal VG2 to the gate of the extraction switch element Q2 of the charge extraction unit 12 via the buffer 142. The drawing switch element Q2 is turned on when the drive signal VG2 is input to the gate (when the drive signal VG2 is high level), and is not input to the gate (the drive signal VG2 is low level). Off). The first control circuit 140 may be configured by a microcontroller that constitutes the second control circuit 141.

  Next, the control operation of the control unit 14 will be described in detail with reference to the time chart shown in FIG. In the time chart shown in FIG. 3, when the second control circuit 141 receives a first control command instructing to turn off the first LED 13 </ b> A in a state where all the LEDs 13 </ b> A to 13 </ b> D of the light emitting unit 13 are turned on. It corresponds to the control action of.

  Here, in a state where all the LEDs 13A to 13D of the light emitting unit 13 are lit, the second control circuit 141 sets the drive signal VG2 to the low level and turns off the extraction switch element Q2. The power supply unit 10 in this state operates so that the voltage value of the output voltage V1 is equal to VF × 4 when the forward voltage during lighting of the four LEDs 13A to 13D is VF. That is, the second control circuit 141 adjusts the voltage value of the second reference voltage Vr2 to a value corresponding to the rated current value of the light emitting unit 13, whereby the first control circuit 140 controls the first switching element Q1 by PWM (pulse width). Modulation) control to make the voltage value of the output voltage V1 equal to VF × 4.

  When the second control circuit 141 receives the first control command instructing to turn off the first LED 13A, the second control circuit 141 instructs the first control circuit 140 to stop the switching of the first switching element Q1 before turning off the first LED 13A. (Time t = t1). For example, if the second control circuit 141 stops the power supply unit 10 by setting the first reference voltage Vr1 in the first control circuit 140 to zero and preventing the drive signal VG1 from being output from the output terminal Q of the oscillator 143. Good. Even if the power supply unit 10 is stopped, the output current I1 continues to flow while decreasing while the electric charge charged in the smoothing capacitor C1 of the voltage conversion circuit 100 is discharged. Further, the output voltage V1 of the power supply unit 10 decreases with the discharge of the smoothing capacitor C1. In addition, the light emission part 13 maintains a lighting state, while the output current I1 flows.

  The second control circuit 141 outputs a high-level drive signal VG2 via the buffer 142 when a predetermined time has elapsed since the power supply unit 10 was stopped (time t = t1), and is used for the extraction of the charge extraction unit 12. The switch element Q2 is turned on. However, the predetermined time (= t2−t1) is preferably a time during which the voltage across the smoothing capacitor C1 is maintained to be equal to or higher than a voltage that can maintain the lighting state of all the LEDs 13A to 13D of the light emitting unit 13. . For example, if the minimum value of the forward voltage VF that can maintain the LEDs 13A to 13D in the lighting state is VFmin, the output voltage V1 at the time t = t2 is substantially equal to VFmin × 4.

  When the extraction switch element Q2 is turned on by the second control circuit 141, the charge extraction unit 12 extracts the charge from the smoothing capacitor C1. When the charge extracting unit 12 extracts the charge of the smoothing capacitor C1, the output voltage V1 of the power supply unit 10 further decreases. The speed at which the output voltage V1 decreases is determined by the product of the capacitance value of the smoothing capacitor C1 and the resistance value of the resistor 120.

  The second control circuit 141 is used to turn on the first switch element Q3 when a predetermined time Tdc has elapsed (time t = t3) from the time when the extraction switch element Q2 is turned on (time t = t2). The control signal is output to the drive circuit 110 of the switching unit 11. When the drive circuit 110 of the switching unit 11 receives the control signal, it outputs a high-level drive signal VG3 and turns on the first switch element Q3. When the first switch element Q3 is turned on, the output current I1 instantaneously changes according to the difference between the output voltage V1 immediately before time t = t3 and the voltage (= VFmin × 3) corresponding to the three LEDs 13B to 13D. After the increase, the output voltage V1 becomes a value equal to VFmin × 3. Then, the second control circuit 141 sets the drive signal VG2 to the low level and turns off the drawing switch element Q2 (time t = t4). Further, the second control circuit 141 restarts the operation of the power supply unit 10 (time t = t5). When the power supply unit 10 resumes operation, the output voltage V1 rises to a voltage (= VF × 3) corresponding to the three LEDs 13B to 13D, and the output current I1 returns to the target value, for example, the rated current value of the LEDs 13B to 13D. To do.

  Here, in the case where the charge charge of the smoothing capacitor C1 is not extracted by the charge extraction unit 12, when the first switch element Q3 is turned on, an excessive output current I1 is instantaneously generated as indicated by a broken line α in FIG. Likely to flow into. On the other hand, in the lighting device 1 of the present embodiment, the first switch element Q3 of the switching unit 11 is switched from OFF to ON after the charge extraction unit 12 extracts the charge of the smoothing capacitor C1. As a result, the voltage across the smoothing capacitor C1 at the time when the first switch element Q3 is turned on is reliably reduced, so that excessive current flowing through the light emitting unit 13 can be reduced. Here, it is preferable that the period Tdc from the time when the extraction switch element Q2 is turned on (time t = t2) to the time when the first switch element Q3 is turned on is a time that satisfies the following conditions. The condition is that the current value of the output current I1 output from the power supply unit 10 when the first switch element Q3 is turned on is equal to or less than the current rated value of the first switch element Q3, and the light emitting unit 13 It is a condition that the current is more than the minimum value required for lighting. When the predetermined period Tdc is as described above, it is possible to reduce the stress applied to the first switch element Q3 by suppressing an increase in current that flows when the first switch element Q3 is turned on.

  When the second control circuit 141 receives the first control command instructing to turn on the first LED 13A again (time t = t6), the second control circuit 141 outputs the drive signal VG3 without performing the charge extraction by the charge extraction unit 12. The first switch element Q3 is turned off by setting it to a low level. The output current I1 of the power supply unit 10 decreases instantaneously immediately after the first switch element Q3 is turned off, but immediately returns to the original current value. The output voltage V1 of the power supply unit 10 returns to the voltage (= VF × 4) corresponding to the four LEDs 13A to 13D after the first switch element Q3 is turned off. Note that the control unit 14 basically performs the same control operation as when the above-described first switch element Q3 is turned on even when the other switch elements Q4 to Q6 are turned on.

  By the way, the second control circuit 141 of the control unit 14 may turn off the extraction switch element Q2 of the charge extraction unit 12 before turning on the switch elements Q3 to Q6 of the switching unit 11. The lighting device 1 can reduce excessive current flowing through the light emitting unit 13 even if the drawing switch element Q2 is turned off before the switch elements Q3 to Q6 of the switching unit 11.

  Further, as shown in the time chart of FIG. 4, the second control circuit 141 of the control unit 14 may operate the power supply unit 10 while the extraction switch element Q2 of the charge extraction unit 12 is turned on ( Time t = t1 to t3). Furthermore, if the resistance value of the resistor 120 of the charge extraction unit 12 is small enough to satisfy the rated capacity of the voltage conversion circuit 100, the second control circuit 141 can be used while the extraction switch element Q2 is turned on. It is only necessary to maintain or decrease the output power of the output. In this case, the charge of the smoothing capacitor C1 is extracted when the extraction switch element Q2 is turned on, and the output voltage V1 of the power supply unit 10 is set to a predetermined value (for example, VFmin × 3) or less when the predetermined time Tdc has elapsed. can do.

  Further, the second control circuit 141 may always turn on the extraction switch element Q2 of the charge extraction unit 12 when dimming the light emitting unit 13 by lowering the target value of the output current I1. By connecting the resistor 120 of the charge extraction unit 12 in parallel with the light emitting unit 13 as a load of the voltage conversion circuit 100, the output voltage V1 of the voltage conversion circuit 100 is stabilized, and the output current I1 can be stably reduced. it can.

  Further, as illustrated in FIG. 5, the charge extracting unit 12 may have a circuit configuration in which a series circuit of a resistor 121 and a switch element 122 is electrically connected to the resistor 120 in parallel. The switch element 122 is preferably turned on / off by the second control circuit 141. When the switch element 122 is turned on, the resistance value of the charge extracting unit 12 becomes a combined resistance value of the resistance values of the two resistors 120 and 121 and becomes smaller than the resistance value of the one resistor 120. For example, the second control circuit 141 preferably turns on the switch element 122 to reduce the resistance value of the charge extracting unit 12 when turning on two or more switch elements Q3 to Q6. As a result, the charge extracting unit 12 can extract the charge stored in the smoothing capacitor C1 in the same time Tdc as when only one switch element Q3 is turned on. Alternatively, the charge extraction unit 12 may have a circuit configuration in which a plurality of series circuits of resistors and extraction switch elements are provided, and the plurality of series circuits are electrically connected in parallel. When the second control circuit 141 turns on two or more switch elements Q3 to Q6, it is preferable to turn on a plurality of drawing switch elements to reduce the resistance value of the charge extracting unit 12.

  As described above, the lighting device 1 includes the power supply unit 10, the switching unit 11, and the charge extraction unit 12. The power supply unit 10 includes a voltage conversion circuit 100 that converts an input voltage into a DC output voltage V1, and a control unit 14 that controls the voltage conversion circuit 100. The voltage conversion circuit 100 is a DC / DC converter having a smoothing capacitor C1 between output terminals. The control unit 14 controls the voltage conversion circuit 100 so that the output current I1 of the voltage conversion circuit 100 is made constant. The switching unit 11 includes one or more switch elements Q3 to Q6 and a drive circuit 110 that turns on or off the one or more switch elements Q3 to Q6, and is electrically connected to the smoothing capacitor C1. Yes. Each of the one or a plurality of switch elements Q3 to Q6 is electrically connected in parallel with a single solid-state light-emitting element or a series circuit of a plurality of solid-state light-emitting elements (first to fourth LEDs 13A to 13D). The charge extraction unit 12 has a series circuit of a resistor 120 and an extraction switch element Q2. The series circuit is electrically connected in parallel with the smoothing capacitor C1. The charge extraction unit 12 is configured to extract the charging charge of the smoothing capacitor C1 by turning on the extraction switch element Q2 before the switch elements Q3 to Q6 of the switching unit 11 are turned on.

  If the lighting device 1 is configured as described above, the charge extraction unit 12 extracts the charged charge and lowers the voltage across the smoothing capacitor C1, and then turns on the switching elements Q3 to Q6 of the switching unit 11 to thereby turn on the solid state. It is possible to reduce an excessive current flowing in the light emitting element.

  In the lighting device 1, the drive circuit 110 of the switching unit 11 includes one or more switch elements Q <b> 3 to Q <b> 6 after a predetermined time Tdc has elapsed since the charge extraction unit 12 turned on the extraction switch element Q <b> 2. It is preferable to turn on at least one of the switch elements Q3 to Q6.

  If the lighting device 1 is configured as described above, it is possible to sufficiently reduce the voltage across the smoothing capacitor C1 and further reduce the excessive current flowing in the solid state light emitting device.

  Furthermore, in the lighting device 1, it is preferable that the control unit 14 lowers the output voltage V1 of the voltage conversion circuit 100 before the charge extraction unit 12 turns on the extraction switch element Q2. The control unit 14 may increase the output voltage of the voltage conversion circuit 100 after the drive circuit 110 of the switching unit 11 turns on at least one of the one or more switch elements Q3 to Q6. preferable.

  If the lighting device 1 is configured as described above, compared to the case where the output voltage V1 of the voltage conversion circuit 100 is not reduced, the voltage across the smoothing capacitor C1 is sufficiently reduced, and an excessive current flows through the solid state light emitting device. Can be further reduced.

  Further, in the lighting device 1, it is preferable that the period Tdc from when the extraction switch element Q2 is turned on to when the switch element Q3 of the switching unit 11 is turned on is a time that satisfies the following condition. The time is such that the current value of the output current I1 output from the power supply unit 10 when the switch element Q3 is turned on is less than or equal to the rated current value of the switch element Q3 that is turned on, and the solid state light emitting elements (LEDs 13B to 13D). This is the time that is equal to or greater than the minimum value of the current required for lighting.

  If the lighting device 1 is configured as described above, it is possible to reduce the stress applied to the switch elements Q3 to Q6 by suppressing an increase in current flowing when the switch elements Q3 to Q6 are turned on.

  Further, in the lighting device 1, the control unit 14 controls the voltage conversion circuit 100 during the period Tdc in which the charge extraction unit 12 turns on the extraction switch element Q <b> 2, and the voltage value of the output voltage V <b> 1 of the power supply unit 10. Is preferably less than or equal to a predetermined value. The predetermined value is the voltage value of the output voltage V1 before the extraction switch element Q2 is turned on.

  If the lighting device 1 is configured as described above, it is possible to shorten the on-period of the extraction switch element Q2 necessary for extracting the charge of the smoothing capacitor C1.

  Further, in the lighting device 1, the control unit 14 switches the voltage conversion circuit 100 after the drive circuit 110 of the switching unit 11 turns on at least one switch element Q <b> 3 among the one or more switch elements Q <b> 3 to Q <b> 6. It is preferable to control as follows. That is, it is preferable that the control unit 14 controls the voltage conversion circuit 100 so that the output voltage V1 is a voltage value corresponding to the number of solid-state light emitting elements that are lit.

  If the lighting device 1 is configured as described above, it is possible to prevent an excessive voltage from being applied to the solid light emitting element that is lit.

  Further, in the lighting device 1, the charge extracting unit 12 may be configured to decrease the resistance value of the resistor as the number of switch elements Q <b> 3 to Q <b> 6 turned on by the drive circuit 110 of the switching unit 11 increases. preferable.

  If the lighting device 1 is configured as described above, regardless of the number of switch elements Q3 to Q6 that are turned on by the drive circuit 110, the time Tdc is the same as when only one switch element Q3 is turned on. The charge extracting unit 12 can extract the charging charge of the smoothing capacitor C1.

  Next, the lamp 4 according to this embodiment will be described. As shown in FIGS. 6 and 7, the lamp 4 preferably includes a lighting device 1, four light source units 5 (5A to 5D), a lamp body 40, a cover 41, and the like. The lamp body 40 is formed of a synthetic resin into a box shape with an open front surface. The cover 41 is formed in a box shape whose rear surface is opened by a light-transmitting material such as glass or acrylic resin. The rear end of the cover 41 is coupled to the front end of the lamp body 40. And four light source units 5A-5D are accommodated in the lamp body 40.

  The four light source units 5 basically have a common structure. Therefore, representatively, the structure of the third light source unit 5C will be described with reference to FIG. The third light source unit 5C includes a third LED 13C, a housing 50, a lens 51, a heat radiating member 52, a reflecting member 53, and the like. The third LED 13C is configured by mounting an LED chip 130C on a mounting substrate 131C. The housing 50 is formed of a metal material in a box shape and accommodates the third LED 13C therein. The lens 51 is formed in a hemispherical shape from a light-transmitting material such as glass or acrylic resin. The lens 51 is attached to the tip of the housing 50. The heat radiating member 52 is formed by, for example, aluminum die casting. The reflecting member 53 is formed in a hemispherical shape from a metal material such as an aluminum plate. The third LED 13 </ b> C is attached to the heat dissipation member 52 so that the mounting substrate 131 </ b> C is in contact with the surface of the heat dissipation member 52. The reflecting member 53 is attached to the heat radiating member 52 so that the third LED 13C can be housed inside. Therefore, the light emitted from the third LED 13 </ b> C is reflected by the inner peripheral surface of the reflecting member 53 and then collected by the lens 51. In addition, as shown in FIG. 7, it is preferable that the four light source units 5A to 5D are arranged in a line in the horizontal direction in the lamp body 40.

  The lighting device 1 is housed in a metal case 16 and attached to the outer surface of the lamp body 40. The lighting device 1 and the four light source units 5A to 5D are electrically connected via an electric wire 54 (see FIGS. 6 and 7).

  Here, in the lamp 4, it is preferable that the resistor 120 of the charge extracting unit 12 is mounted on any one of the four light source units 5, for example, the mounting substrate 131 </ b> C of the third light source unit 5 </ b> C. That is, the lamp 4 can efficiently dissipate Joule heat generated from the resistor 120 by the heat dissipating member 52 when the extraction switch element Q2 is turned on and a discharge current flows through the resistor 120. Therefore, since the resistor 120 is provided outside the case 16, the heat sink for the resistor 120 is not accommodated in the case 16. As a result, the lamp 4 can reduce the size of the lighting device 1 as compared with the case where the heat radiating plate for the resistor 120 is accommodated in the case 16. Furthermore, since the heat dissipation plate for the resistor 120 is also used as the heat dissipation member 52 for the LED 13C, the lamp 4 can reduce the number of parts.

  The vehicle 6 according to the present embodiment is preferably, for example, a sedan type ordinary passenger car (see FIG. 8). The lamp 4 according to the present embodiment is disposed on both the left and right sides of the front end portion of the vehicle body 60 of the vehicle 6. That is, the lamp 4 according to the present embodiment is preferably used for a headlamp of the vehicle 6.

  As described above, the lamp 4 includes the solid light emitting element lighting device 1, one or more solid light emitting elements (LEDs 13 </ b> A to 13 </ b> D) that are turned on by the solid light emitting element lighting device 1, and one or more solid light emitting elements. And a lamp body 40 to be accommodated.

  If the lamp 4 is configured as described above, it is possible to reduce excessive current flowing in the solid state light emitting device.

  In addition, the lamp 4 preferably has a heat dissipation member 52 accommodated in the lamp body 40. The heat dissipating member 52 is preferably thermally coupled to the solid state light emitting device and the resistor 120 of the charge extracting unit 12.

  If the lamp 4 is configured as described above, it is possible to reduce the number of parts by using the solid-state light emitting element and the resistor 120 as the heat radiating member 52.

  As described above, the vehicle 6 includes the lamp 4 and the vehicle body 60 on which the lamp 4 is mounted.

  If the vehicle 6 is configured as described above, it is possible to reduce excessive current flowing in the solid state light emitting device.

DESCRIPTION OF SYMBOLS 1 Solid light emitting element lighting device 4 Lamp 6 Vehicle 10 Power supply part 11 Switching part 12 Charge extraction part 13A 1st LED (solid light emitting element)
13B 2nd LED (solid state light emitting device)
13C 3rd LED (solid state light emitting device)
13D 4th LED (solid state light emitting device)
DESCRIPTION OF SYMBOLS 14 Control part 40 Lamp main body 52 Heat radiating member 100 Voltage conversion circuit 110 Drive circuit Q2 Extraction switch element Q3-Q6 Switch element C1 Smooth capacitor

Claims (10)

A power supply unit, a switching unit, and a charge extraction unit;
The power supply unit includes a voltage conversion circuit that converts an input voltage into a DC output voltage, and a control unit that controls the voltage conversion circuit,
The voltage conversion circuit is a DC / DC converter having a smoothing capacitor between output terminals,
The control unit controls the voltage conversion circuit to make the output current of the voltage conversion circuit constant.
The switching unit includes one or more switch elements and a drive circuit that turns on or off the one or more switch elements, and is electrically connected in parallel with the smoothing capacitor;
Each of the one or more switching elements is electrically connected in parallel with one solid light emitting element or a series circuit of a plurality of solid light emitting elements,
The charge extraction unit has a series circuit of a resistor and an extraction switch element, and the series circuit is electrically connected in parallel with the smoothing capacitor,
The solid state light emitting device lighting device, wherein the charge extraction unit is configured to extract the charge of the smoothing capacitor by turning on the extraction switch element before the switch element of the switching unit is turned on.   The drive circuit of the switching unit turns on at least one switch element of the one or a plurality of switch elements after a predetermined time has elapsed since the charge extraction unit turned on the extraction switch element. Item 2. The solid state light emitting device lighting device according to Item 1. The control unit lowers the output voltage of the voltage conversion circuit before the charge extraction unit turns on the extraction switch element,
3. The solid state according to claim 2, wherein the control unit raises the output voltage of the voltage conversion circuit after the drive circuit of the switching unit turns on at least one of the one or more switch elements. 4. Light emitting element lighting device.   During the period from when the drawing switch element is turned on to when the switch element of the switching unit is turned on, the current value of the output current output from the power supply unit when the switch element is turned on is turned on. 4. The solid state light emitting element lighting device according to claim 2, wherein the time is equal to or shorter than a current rated value of the switch element and equal to or longer than a minimum value of a current required for lighting the solid state light emitting element.   The control unit controls the voltage conversion circuit to turn on the extraction switch element by controlling the voltage conversion circuit during a period in which the charge extraction unit is turning on the extraction switch element. The solid-state light-emitting element lighting device according to any one of claims 1 to 4, wherein the solid-state light-emitting element lighting device is set to be equal to or lower than a voltage value before the operation.   The solid-state light emitting element in which the control unit is lighting the output voltage of the voltage conversion circuit after the drive circuit of the switching unit turns on at least one of the one or more switch elements The solid-state light-emitting element lighting device according to claim 3, wherein the voltage conversion circuit is controlled to have a voltage value corresponding to the number of the light-emitting elements.   7. The device according to claim 1, wherein the charge extracting unit is configured to decrease a resistance value of the resistor as the number of the switch elements turned on by the driving circuit of the switching unit increases. The solid-state light-emitting element lighting device described.   A solid light emitting element lighting device according to any one of claims 1 to 7, one or more solid light emitting elements that are turned on by the solid light emitting element lighting device, and the one or more solid light emitting elements. A lamp having a lamp body to be accommodated. Having a heat dissipating member housed in the lamp body,
The lamp according to claim 8, wherein the heat radiating member is thermally coupled to the solid light emitting element and the resistance of the charge extraction unit.   A vehicle comprising the lamp according to claim 8 and a vehicle body on which the lamp is mounted.

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