CN104823528B - Lighting apparatus for discharge lamp and the headlamp of this lighting apparatus for discharge lamp of use - Google Patents

Abstract

When the output voltage or output current to the high-pressure discharge lamp measured by the measurement unit is within the abnormal range, the control unit reduces the power supply to the high-pressure discharge lamp. The drive section for driving the switching element is equipped with a capacitor for supplying required charges to the control electrode of the switching element on the high potential side to turn on the high potential side when the switching element on the low potential side is off. Switching element on the potential side. In the case of starting the high-pressure discharge lamp, the charging of the capacitor starts before the DC/DC converter starts to operate, and in the state where the DC/DC converter and the DC/AC inverter are operated after the charging of the capacitor is completed, discharge The lamp lighting device is provided with a determination period in which the control unit determines the presence or absence of an abnormality based on the measurement value measured by the measurement section.

Description

Discharge lamp lighting device and headlamp using the discharge lamp lighting device

technical field

The present invention relates to a discharge lamp lighting device and a headlamp using the discharge lamp lighting device.

Background technique

Conventionally, a high-pressure discharge lamp lighting device for lighting a high-pressure discharge lamp has been proposed (for example, see Japanese Patent Laid-Open No. 2010-135195 (hereinafter referred to as "Document 1")). In the high-pressure discharge lamp lighting device disclosed in Document 1, the full bridge circuit converts the DC (direct current) output of the step-down chopper circuit into AC (alternating current) current having a rectangular wave and supplies the AC current to the lamp ( high pressure discharge lamp).

In this high-pressure discharge lamp lighting device, by applying a high-voltage pulse to the lamp using an ignition circuit at startup, insulation breakdown of the lamp is caused, and glow discharge occurs. Afterwards, the lamp changes from a glow discharge to an arc discharge, whereby the luminous flux rises.

The full-bridge circuit is configured by connecting the first arm and the second arm each formed by a series circuit of two transistors in parallel to each other, so that groups of transistors located at the diagonal are simultaneously in the ON state, And switch on/off (On/Off) of each group alternately. Here, among the transistors constituting each arm, when the transistor on the low potential side is off, the transistor on the high potential side is turned on. Therefore, in order to turn on the transistor on the high potential side, a bootstrap capacitor (bootstrap capacitor) for supplying charge to the gate electrode of the transistor is arranged.

Here, in the no-load state before starting the discharge lamp, it is conceivable to shorten the time until the output voltage of the step-down chopper circuit is raised to a predetermined voltage by operating the step-down chopper circuit during the process of charging the bootstrap capacitor. The time required to quickly perform the start-up operation. However, in the case of operating the full bridge circuit in a state in which the output voltage of the step-down chopper circuit rises by operating the step-down chopper circuit during the process of charging the bootstrap capacitor, when the load forms When there is a short circuit, there is a problem of overcurrent flowing through the circuit.

In addition, in the high-pressure discharge lamp lighting device disclosed in Document 1, when the step-down chopper circuit is a non-isolated type, when the load is short-circuited at the time of startup, even when the step-down chopper circuit is stopped, from The energy input on the power supply side is also transferred to the output side, and there is a problem that an overcurrent flows through the circuit.

Contents of the invention

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a discharge lamp lighting device configured so that it is difficult for an overcurrent to flow through a circuit in the event of an abnormality such as a short circuit, and a lamp point using the discharge lamp. Turn on the headlights of the unit.

A discharge lamp lighting device according to the present invention includes: a DC/DC converter configured to convert an input voltage input from a DC power supply into a voltage value required to light the discharge lamp by performing switching; A DC/AC inverter including a bridge circuit in which a first switching element disposed on the high potential side and a first switching element disposed on the low potential side are connected between output terminals of the DC/DC converter. at least one series circuit of the second switching element on the potential side, and the DC/AC inverter is configured to convert the DC output of the DC/DC converter into an AC output and supply the AC output to a circuit comprising the a load of the discharge lamp; a driving section configured to turn on the DC/DC converter by alternately turning on the first switching element and the second switching element at least in a stable lighting period at a predetermined period; a DC output converted into an AC output obtained by alternating the polarity of the DC output at a predetermined cycle; a measuring section configured to measure at least one of an output voltage and an output current to the load; and a control a part configured to reduce the power supplied to the discharge lamp compared to the power supplied to the discharge lamp when the measured value measured by the measuring part is in an abnormal range, wherein the The drive section includes a capacitor configured to supply a required charge to the control electrode of the first switching element arranged on the high potential side to turn off the second switching element arranged on the low potential side. turns on the first switching element when turned on, charges the capacitor when the second switching element is turned on, and charges the capacitor when starting the discharge lamp. The capacitor starts to be charged before the converter starts to work, and the control unit sets There is a judging period for judging the presence or absence of an abnormality based on the measurement value measured by the measuring unit.

In the discharge lamp lighting device, preferably, the control section is configured to stop the DC/DC conversion if the measurement value measured by the measurement section within the determination period is within an abnormal range. device switching operation.

In addition, in the discharge lamp lighting device, preferably, the control section is configured to detect an abnormality in the load based on a measurement value measured by the measurement section within the determination period. Whether there is a short circuit.

In addition, in the discharge lamp lighting device, preferably, in the case where the control section determines that there is no abnormality within the determination period, the drive section is configured to charge the capacitor again.

In addition, in the discharge lamp lighting device, preferably, the measurement section is configured to measure the output current of the DC/DC converter within the determination time period, and the current measured by the measurement section The control unit is configured to determine that a short circuit has occurred in the load when the current value is equal to or greater than a predetermined threshold current.

In addition, in the discharge lamp lighting device, preferably, the measurement section is configured to measure the output voltage of the DC/DC converter within the determination time period, and the voltage measured by the measurement section The control unit is configured to determine that a short circuit has occurred in the load when the voltage value is equal to or less than a predetermined threshold voltage.

In addition, in the discharge lamp lighting device, preferably, the measurement section is configured to measure both the output current and the output voltage of the DC/DC converter during the determination period, and to measure both the output current and the output voltage of the DC/DC converter during the The control unit is configured to determine that a short circuit has occurred in the load when the current value measured by the measurement unit is equal to or greater than a predetermined threshold current and the voltage value measured by the measurement unit is equal to or less than a predetermined threshold voltage. .

In addition, in the discharge lamp lighting device, preferably, when it is determined that an abnormality has occurred within the determination time period, the control unit is configured to turn off at least all the first switching element.

In addition, in the discharge lamp lighting device, preferably, the DC/DC converter is a non-isolated DC/DC converter.

A headlamp according to the present invention includes one of the above-mentioned discharge lamp lighting devices.

According to the present invention, it is possible to realize a discharge lamp lighting device that suppresses an overcurrent from flowing through a circuit when an abnormality such as a short circuit occurs.

In addition, it is possible to realize a headlamp that suppresses an overcurrent from flowing through the circuit of the discharge lamp lighting device when an abnormality such as a short circuit occurs.

Description of drawings

FIG. 1 is a circuit diagram of a discharge lamp lighting device according to Embodiment 1. Referring to FIG.

FIG. 2 is a circuit diagram showing a main part of a discharge lamp lighting device according to Embodiment 1. FIG.

3 is a waveform diagram illustrating the operation of the discharge lamp lighting device according to Embodiment 1 from the time of starting up to the time of stable lighting.

4 is a waveform diagram illustrating the operation of a DC/AC inverter of the discharge lamp lighting device according to Embodiment 1. FIG.

5A to 5G are waveform diagrams of each unit illustrating the operation of the discharge lamp lighting device according to Embodiment 1. FIGS.

6A to 6H are waveform diagrams of each unit illustrating the operation of the discharge lamp lighting device according to Embodiment 2. FIGS.

7A to 7H are waveform diagrams of each unit illustrating another operation of the discharge lamp lighting device according to Embodiment 2. FIGS.

8A to 8I are waveform diagrams of each unit illustrating still another operation of the discharge lamp lighting device according to Embodiment 2. FIGS.

9A to 9G are waveform diagrams of each unit illustrating still another operation of the discharge lamp lighting device according to Embodiment 2. FIGS.

10A to 10H are waveform diagrams of each unit illustrating still another operation of the discharge lamp lighting device according to Embodiment 2. FIGS.

FIG. 11 is a circuit diagram of a discharge lamp lighting device according to Embodiment 3. FIG.

12A to 12I are waveform diagrams of each unit illustrating the operation of the discharge lamp lighting device according to Embodiment 3. FIG.

13A to 13I are waveform diagrams of each unit illustrating the operation of the discharge lamp lighting device according to Embodiment 3. FIGS.

FIG. 14 is a diagram schematically showing a vehicle mounted with a headlamp according to Embodiment 4. FIG.

detailed description

Embodiments in which the discharge lamp lighting device according to the present invention is applied to a lighting device for a high pressure discharge lamp will be described below with reference to the drawings. As examples of high-pressure discharge lamps, there are metal halide lamps, high-pressure sodium lamps, and the like. These high-pressure discharge lamps have high brightness and long life compared with incandescent lamps, and are also used as headlights for vehicles.

Example 1

FIG. 1 shows a circuit diagram of a discharge lamp lighting device A according to the present embodiment. This discharge lamp lighting device A includes a DC/DC converter 1, a DC/AC inverter 2, a measurement unit 3, a control unit 4, a starting auxiliary circuit unit 5, a starting voltage generating circuit unit 6, an ignition unit 7, a power supply voltage Measuring part 8 , temperature measuring part 9 and driving part 10 .

The DC/DC converter 1 includes a flyback converter circuit for boosting the power supply voltage of the DC power supply E1 to a desired voltage value. The DC/DC converter 1 includes a transformer T1, a switching element Q1 composed of field effect transistors, a diode D1, and capacitors C1 and C2. The capacitor C1 is connected to both ends of the DC power supply E1 via the power switch SW1. A series circuit of the primary winding P1 of the transformer T1 and the switching element Q1 is connected to both ends of the capacitor C1. One end side of the secondary winding S1 of the transformer T1 is connected to the negative electrode side of the DC power supply E1, and the capacitor C2 is connected between both ends of the secondary winding S1 via a diode D1. Here, the winding directions of the primary winding P1 and the secondary winding S1 of the transformer T1 are opposite to each other.

The DC/AC inverter 2 includes switching elements Q2 to Q5 each composed of field effect transistors and a drive circuit (drive unit) 2a. The DC/AC inverter 2 is configured to convert the DC voltage output from the DC/DC converter 1 into a low-frequency rectangular-wave AC voltage, and supply the AC voltage to a load 11 including a high-pressure discharge lamp LP1 (see FIG. 2 ). A first arm consisting of a series circuit of switching elements Q2 and Q4 and a second arm consisting of a series circuit of switching elements Q3 and Q5 are connected between output terminals of the DC/DC converter 1 . A high-pressure discharge lamp LP1 as a load is connected via an ignition unit 7 between a connection point X1 of switching elements Q2 and Q4 constituting the first arm and a connection point X2 of switching elements Q3 and Q5 constituting the second arm. Here, the switching elements Q2 to Q5 constituting the DC/AC inverter 2 are not limited to FETs, but may be, for example, switching elements such as bipolar transistors or IGBTs.

The measuring section 3 is configured to measure the output voltage V3 and the output current I1 to the high-pressure discharge lamp LP1 as a load. In this embodiment, in order to measure the output voltage V3, the measurement section 3 includes a series circuit of resistors R1, R2, and R3 connected to the output terminal on the high potential side of the DC/DC converter 1, and measures the voltage relative to the output voltage V3. proportional to the voltage V5. In addition, the measuring section 3 includes a resistor R4 for current detection connected between the DC/DC converter 1 and the DC/AC inverter 2 in order to measure the output current I1, and according to the output current I1 in the resistor R4 flow to measure the voltage V4 developed across the resistor R4.

The start-up assisting circuit section 5 includes a series circuit of resistors R5 , R6 , and a capacitor C3 connected between output terminals of the DC/DC converter 1 , and a diode D2 connected in parallel to the resistor R6 . The anode of diode D2 is connected to capacitor C3 and the cathode of diode D2 is connected to resistor R5. The capacitor C3 is charged according to the output voltage of the DC/DC converter 1 at the time of no load before the high-pressure discharge lamp LP1 is started. Then, immediately after the high-pressure discharge lamp LP1 is turned on, during the period in which the DC/DC converter 1 cannot operate, in order not to turn off the high-pressure discharge lamp LP1, the charge obtained by charging the capacitor C3 is passed through the diode D2 and Resistor R5 supplies to high pressure discharge lamp LP1.

The start-up voltage generation circuit section 6 is a circuit for generating a high voltage for causing the discharge gap SG1 of the ignition section 7 to be described later to be broken down, and is, for example, a multistage booster circuit composed of capacitors and diodes or a winding circuit based on a transformer. Compared with the boost circuit for boosting the voltage, etc.

The ignition unit 7 includes a step-up transformer T2, a discharge gap SG1, and capacitors C4 and C5. The capacitor C4 is connected between the connection point X1 and the connection point X2, and the capacitor C5 is connected between the output terminal of the starting voltage generating circuit section 6 and the connection point X2. In addition, the series circuit of the secondary winding S2 of the step-up transformer T2 and the high-pressure discharge lamp LP1 is connected between the connection point X1 and the connection point X2, and the series circuit of the primary winding P2 of the step-up transformer T2 and the discharge gap SG1 is connected at startup between the output terminal of the voltage generation circuit unit 6 and the connection point X2. At the time of starting/lighting operation, a high voltage is applied from the starting voltage generating circuit section 6 to the discharge gap SG1, and when the discharge gap SG1 is broken down, a high voltage of about several tens of kV boosted according to the winding ratio The pulses are applied to the high pressure discharge lamp LP1 via the secondary winding S2.

The control section 4 includes a power target storage section 4a, a stable power limiting section (steady power control section) 4b, a current target calculation section 4c, an error amplifier 4d, a drive control section 4e, and an abnormality judging section 4f, and is configured to control the switching element Q1 ~ On/off of Q5.

In the power target storage unit 4a, a target value of power output from the DC/DC converter 1 is stored in advance. The stable power limiting section 4b corrects the target value of the electric power stored in the electric power target storage section 4a based on the temperature measured by the temperature measuring section 9 or the power supply voltage of the DC power supply E1 measured by the power supply voltage measuring section 8, and sets the corrected The subsequent target value is output to the current target calculation unit 4c. The current target calculating section 4c acquires the target value of the output current I1 by dividing the target value of the electric power input from the steady power limiting section 4b by the output voltage acquired based on the voltage V5 measured by the measuring section 3 . The error amplifier 4d compares the target value of the output current I1 acquired by the current target calculation section 4c with the output current I1 acquired based on the voltage V4 measured by the measurement section 3, and amplifies the error between the two The acquired signal is output to the drive unit 10 . The driving section 10 controls the duty ratio of the signal LF3 to be applied to the gate electrode of the switching element Q1 according to the signal input from the error amplifier 4d so that the measured value of the output current I1 coincides with a target value.

By controlling the operation of the drive circuit 2a, the drive control unit 4e switches ON/OFF of the four switching elements Q2 to Q5 included in the DC/AC inverter 2 . Here, the on/off operation of the switching elements Q2 to Q5 will be described in more detail with reference to the circuit diagram of FIG. 2 . FIG. 2 shows details of a circuit portion for driving the switching elements Q2 and Q4 constituting the first arm, and does not show other circuit configurations.

Between the connection point X1 of the switching elements Q2 and Q4 and the connection point X2 of the switching elements Q3 and Q5, a load 11 including a high-pressure discharge lamp LP1 is connected.

The drive circuit 2a includes a drive circuit 22 connected between the gate and source of the switching element (first switching element) Q2 on the high potential side, and a gate connected to the switching element (second switching element) Q4 on the low potential side. The drive circuit 24 between the pole and the source. The driving circuit 24 for driving the second switching element Q4 arranged on the low potential side receives an operating voltage from a driving power source (not shown) that receives power supply from the DC power source E1 and generates operating power for the control unit 4 and the like. Vcc. On the other hand, the drive circuit 22 for driving the first switching element Q2 arranged on the high potential side turns on the first switching element Q2 in the off state of the second switching element Q4 arranged on the low potential side. , using the charges charged in the bootstrap capacitor C6 to turn on the first switching element Q2 (current path RT1 shown in FIG. 2 ). One end of the bootstrap capacitor C6 is connected to the power supply for driving via the diode D3, and the other end of the bootstrap capacitor C6 is connected to the connection point X1.

By turning on the first switching elements Q2 and Q3 and the second switching elements Q4 and Q5 alternately at a predetermined period at least when they are turned on stably, the drive circuit 2a is configured so that the DC output of the DC/DC converter 1 Alternate the polarity of the DC output at a predetermined cycle to convert the DC output to an AC output.

In the case of starting the high pressure discharge lamp LP1 , the abnormality judging portion 4 f is configured to judge the presence or absence of abnormality based on at least one of the output voltage and the output current measured by the measuring portion 3 .

Next, the operation of the discharge lamp lighting device A will be described. As shown in FIG. 3 , the discharge lamp lighting device A transitions to a stable lighting mode MD5 through four operation modes MD1 - MD4 .

The mode MD1 shown in FIG. 3 is an operation mode at no load before the high-pressure discharge lamp LP1 is started, and the high-pressure discharge lamp LP1 is in an open state. In the case where the power switch SW1 is turned on in the activation mode MD1 , the control section 4 starts to operate and starts the step-up operation of the DC/DC converter 1 . When the drive section 10 turns on the switching element Q1 in response to the control signal sent from the control section 4 , current flows from the DC power source E1 to the primary winding P1 of the transformer T1 and the switching element Q1 . At this time, due to the rectification effect of the diode D1, the current does not flow through the secondary winding S1, and energy is stored in the transformer T1. Thereafter, when drive unit 10 turns off switching element Q1 in response to a control signal sent from control unit 4 , current flows through the path of secondary winding S1→diode D1→capacitor C2→secondary winding S1. Therefore, the energy stored in the transformer T1 with the switching element Q1 turned on is transferred to the capacitor C2. The duty ratio of the switching element Q1 is controlled by the control unit 4 so that the output voltage V2 of the DC/DC converter 1 is controlled to a target value. The DC/DC converter 1 performs the boosting operation as described above, whereby the output voltage V2 rises.

Thereafter, in the case of shifting to the activation mode MD2, the control section 4 turns on the switching elements Q2 and Q5 and turns off the switching elements Q3 and Q4. In the case where the output voltage V2 gradually increases according to the step-up operation of the DC/DC converter 1, the voltage of the capacitor C4 of the ignition part 7 also rises. On the other hand, in the case where the voltage applied to both ends of the capacitor C5 exceeds a predetermined threshold level according to an increase in the output voltage of the starting voltage generating circuit section 6, the discharge gap SG1 is broken down, and the primary winding of the step-up transformer T2 P2 applies a high voltage. At this time, a high-voltage pulse (about several tens of kV) obtained by boosting the high voltage applied to the primary side according to the winding ratio is generated in the secondary winding S2. With this high-voltage pulse applied to the high-pressure discharge lamp LP1, insulation breakdown occurs in the high-pressure discharge lamp LP1, and glow discharge starts. Immediately after the start of the glow discharge, extinguishment may easily occur because the electrode temperature of the high-pressure discharge lamp LP1 is low. Therefore, in this embodiment, in order to suppress the occurrence of extinguishing, the DC phase mode MD3 in which the current having the same direction continuously flows to both electrodes for a time longer than the time of stable lighting is arranged. In addition, in the first period t2 which is the first half of the DC phase mode MD3, the switching elements Q2 and Q5 are turned on, the switching elements Q3 and Q4 are turned off, and a current having the same direction as that of the current in the activation mode MD2 flows. Path of connection point X1→high pressure discharge lamp LP1→connection point X2. Furthermore, in the second period t3 which is the second half of the DC phase mode MD3, the switching elements Q2 and Q5 are turned off, the switching elements Q3 and Q4 are turned on, and the direction is made to be the same as that of the current in the first period t2. The opposite current flows in the path of connection point X2→high pressure discharge lamp LP1→connection point X1.

When it is determined that the temperatures of the two electrodes are sufficiently high, the control unit 4 ends the DC phase mode MD3. Then, by controlling the drive circuit 2a to alternately turn on the set of switching elements Q2 and Q5 and the set of switching elements Q3 and Q4 at a predetermined period, the control section 4 converts the DC output into an AC output of a rectangular wave, and outputs the AC output It is supplied to the high-pressure discharge lamp LP1. In addition, the control section 4 compares the target value of the output current acquired based on the target value of the output power or the like with the measured value by using the error amplifier 4d, and controls the DC by adjusting the duty ratio of the switching element Q1 according to the amount of error. output power W1 of /DC converter 1 (modes MD4 and MD5). Here, the mode MD4 is the operation mode of the transient state, and the mode MD5 is the operation mode of steady lighting.

As described above, the discharge lamp lighting device A according to the present embodiment performs stable lighting of the high-pressure discharge lamp LP1 (stable lighting mode MD5 ) in the modes MD1 to MD4 described above.

Here, the DC/AC inverter 2 according to the present embodiment is an electrostatic potential type, and at a time t1 from the no-load operation mode MD1 before starting the high-pressure discharge lamp LP1 until the first period t2 of the DC phase mode MD3 Within, the switching elements Q2 and Q5 need to be turned on continuously. In order to continuously turn on the switching elements Q2 and Q5 for a predetermined time, it is necessary to store in the bootstrap capacitor C6 an electric charge required to make the first switching element Q2 operate in the on state for the predetermined time, wherein the bootstrap capacitor C6 This charge is supplied to the gate electrode of the first switching element Q2 arranged on the high potential side. In addition, in the present embodiment, in order to improve the starting characteristics of the high-pressure discharge lamp LP1, the operation of the DC/DC converter 1 is started during the charging process of the bootstrap capacitor C6, and the output voltage V2 of the DC/DC converter 1 is boosted. The time taken for the predetermined voltage is shortened.

Here, the on/off operations of the switching elements Q2 to Q5 constituting the DC/AC inverter 2 and the operation of the bootstrap capacitor C6 provided on the side of the first switching element Q2 disposed on the high potential side will be described with reference to FIG. 2 . Charging operation. The ON/OFF operations of the switching elements Q2 to Q5 are determined based on the control signals LF1 and LF2 input to the drive circuit 2 a from the drive control section 4 e of the control section 4 .

The control signal input to the drive circuit 2 a from the drive control unit 4 e is boosted to a voltage required for driving the gate electrode by the drive circuits 22 and 24 . Here, since the second switching element Q4 disposed on the low potential side is turned off when the first switching element Q2 disposed on the high potential side is turned on, the drive circuit 22 uses the electric charge charged in the bootstrap capacitor C6 to The turn-on voltage is supplied to the gate electrode of the first switching element Q2. During the period when the first switching element Q2 is turned on, the bootstrap capacitor C6 is in a discharged state without being charged, and then the bootstrap capacitor C6 is charged again when the first switching element Q2 is turned off and the second switching element Q4 is switched on. Capacitor C6 is charged. At this time, current flows from the drive power supply through the path of diode D3→bootstrap capacitor C6→second switching element Q4, as indicated by broken line RT2 in FIG. 2, thereby charging bootstrap capacitor C6. Therefore, when charging the bootstrap capacitor C6, the control unit 4 needs to output the signal LF1 for turning off the first switching element Q2 arranged on the high potential side and the signal LF1 for turning off the second switching element Q4 arranged on the low potential side. Signal LF2 turned on. This charging method is called a bootstrap method. Also, for the first switching element Q3 and the second switching element Q5 constituting the second arm, the bootstrap capacitor (not shown in the figure) for driving the first switching element Q3 arranged on the high potential side is set in the same way. Out) to charge, so the description of the bootstrap capacitor is omitted.

In addition, in the transient operation mode MD4 and the steady lighting mode MD5, the control unit 4 alternately controls the switching elements Q2 to Q5 so that the DC output of the DC/DC converter 1 is converted into AC and supplied to the high pressure discharge lamp LP1. As shown in FIG. 4, when the signal level of the signal LF1 is at the high level H and the signal level of the signal LF2 is at the low level L, the gate voltages of the switching elements Q2 and Q5 become high level H, Switching elements Q2 and Q5 are turned on, and switching elements Q3 and Q4 are turned off. On the other hand, when the signal level of signal LF1 is low level L and the signal level of signal LF2 is high level H, the gate voltages of switching elements Q3 and Q4 become high level H, and the switching elements Q3 and Q4 are turned on, and switching elements Q2 and Q5 are turned off. Then, by alternately repeating the period of the high level H of the signal LF1 and the period of the high level H of the signal LF2, ON/OFF of the group of the switching elements Q2 and Q5 and the group of the switching elements Q3 and Q4 are alternately switched. is turned on, thereby converting the output of the DC/DC converter 1 into AC. In addition, between the time period of the high level H of the signal LF1 and the time period of the high level H of the signal LF2, in order not to simultaneously turn on all the switching elements Q2 to Q5, the signal levels of the two signals LF1 and LF2 are set. Both are in the dead time td of low level L. In addition, when the two signals LF1 and LF2 are both at the high level H, the first switching elements Q2 and Q3 arranged on the high potential side are turned off, and the second switching elements Q4 and Q5 arranged on the low potential side are turned on. , and an operation of charging the bootstrap capacitors driving the first switching elements Q2 and Q3 is performed.

Here, also in this embodiment, in the case where the load (for example, the high-pressure discharge lamp LP1) 11 is short-circuited at the time of starting the high-pressure discharge lamp LP1, there is The stored charge and therefore the possibility of excess current flowing through the circuit.

Therefore, in the present embodiment, as shown in FIGS. 5A to 5G , when the supply of the DC power supply E1 is started, before the time t11 at which the DC/DC converter 1 starts to operate and before the time t11 of the DC/DC converter 1 Before the output voltage V2 reaches the predetermined voltage V0, the control section 4 starts the operation for charging the bootstrap capacitor (time period t10 shown in FIGS. 5A to 5G ). Here, the predetermined voltage V0 is, for example, a threshold voltage (approximately 15 V) of the output voltage determined by the control unit 4 as a load short circuit. 5A to 5G are waveform diagrams of each unit at startup. 5A shows the input voltage V1 of the DC/DC converter 1 , FIG. 5B shows a signal LF1 sent from the control section 4 , and FIG. 5C shows a signal LF2 sent from the control section 4 . In addition, FIG. 5D shows the output voltage V2 of the DC/DC converter 1, and FIG. 5E shows the voltage V3 applied to the high-pressure discharge lamp LP1. Furthermore, FIG. 5F shows the signal LF3 sent from the control section 4, and FIG. 5G shows the output current I1 flowing through the high-pressure discharge lamp LP1.

Then, at time t11 after the charging of the bootstrap capacitor is completed, the control section 4 applies the output voltage V2 of the DC/DC converter 1 to the load (high voltage Discharge lamp LP1). Until the predetermined time t12 has elapsed from time t11, the abnormality determination unit 4f of the control unit 4 is based on at least one of the output voltage V3 (actually voltage V5) and the output current I1 (actually voltage V4) measured by the measurement unit 3. One to judge whether there is an abnormality in the load. This time t12 is a judging period for judging whether there is an abnormality in the load (for example, a short circuit or a ground fault in the load).

When the load is short-circuited, the load impedance is significantly lower than the normal load impedance, so the potential difference generated between the output terminals of the DC/DC converter 1 is significantly lower than the normal potential difference, so that the overcurrent occurs at flows between the output terminals of the DC/AC inverter 2 .

When determining the presence or absence of abnormality based on the output voltage to the load, abnormality determination unit 4f compares voltage V5 proportional to output voltage V3 with a voltage value corresponding to a predetermined threshold voltage. Then, when the output voltage V3 is equal to or lower than the threshold voltage, in other words, when the voltage V5 is equal to or lower than the voltage corresponding to the threshold voltage, the abnormality determination unit 4f determines that an abnormality has occurred. On the other hand, when the voltage V5 is higher than the voltage corresponding to the threshold voltage, the abnormality determination unit 4f determines that there is no abnormality.

On the other hand, when determining the presence or absence of abnormality based on the output current to the load, abnormality determination unit 4f compares voltage V4 proportional to output current I1 with a voltage value corresponding to a predetermined threshold current. Then, when the output current I1 is equal to or greater than the threshold current, in other words, when the voltage V4 is equal to or greater than the voltage corresponding to the threshold current, the abnormality determination unit 4f determines that an abnormality has occurred. On the other hand, when the voltage V4 is lower than the voltage corresponding to the threshold current, the abnormality determination unit 4f determines that there is no abnormality.

In the case where it is judged by the abnormality judging part 4f that there is no abnormality in the judgment period t12, the control part 4 continues the start-up operation (the no-load operation mode MD1), and performs the stabilization of the high-pressure discharge lamp LP1 via the modes MD2 to MD4 described above. Bright. On the other hand, when it is judged by the abnormality judging portion 4f that there is an abnormality in the judgment period t12, the control portion 4 does not continue the start-up operation, but stops the operation of the DC/DC converter 1 and the DC/AC inverter 2 (Time t13 shown in FIGS. 5A to 5G ).

The discharge lamp lighting device according to the present embodiment described above includes the DC/DC converter 1 , the DC/AC inverter 2 , the drive section (drive circuit 2 a ), the measurement section 3 and the control section 4 . The DC/DC converter 1 is configured to convert the input voltage V1 input from the DC power source E1 into a voltage value required to light the discharge lamp LP1 by performing switching. The DC/AC inverter 2 includes at least one in which first switching elements Q2 and Q3 arranged on the high potential side and second switching elements Q4 and Q5 arranged on the low potential side are connected between the output terminals of the DC/DC converter 1 . A bridge circuit of a series circuit and configured to convert the DC output of the DC/DC converter 1 into an AC output and supply the AC output to a load including the discharge lamp LP1. The driving section is configured to convert the DC output of the DC/DC converter 1 into DC The polarity of the output alternates the acquired AC output at a predetermined period. The measuring section 3 is configured to measure at least one of the output voltage V3 and the output current I1 to the load. When the measurement value measured by the measurement unit 3 is in the abnormal range, the control unit 4 is configured to reduce the power supply to the discharge lamp LP1 compared to the normal power supply. The driving section includes a capacitor (bootstrap capacitor C6) which supplies required charges to the control electrodes of the first switching elements Q2 and Q3 arranged on the high potential side to The first switching elements Q2 and Q3 are turned on while the second switching elements Q4 and Q5 on the side are turned off. The capacitor is charged when the second switching elements Q4 and Q5 are switched on. In the case where the discharge lamp LP1 starts to operate, the charging of the capacitor starts before the DC/DC converter 1 starts to operate, and the DC/DC converter 1 and the DC/AC inverter 2 operate after the charging of the capacitor is completed. In the state of , the control part 4 has a judgment period t12 for judging whether there is an abnormality based on the measurement value acquired by the measurement part 3 .

As described above, in the case of starting the discharge lamp (the no-load operation mode MD1 shown in FIG. 3 ), the control unit 4 starts charging the bootstrap capacitor before the DC/DC converter 1 starts operating. Then, in a state where the DC/DC converter 1 and the DC/AC inverter 2 are operating after the charging of the bootstrap capacitor is completed, the setting control section 4 determines whether there is an abnormality based on the measurement value acquired by the measurement section 3 Judgment period t12. Then, when the measured value acquired by the measurement unit 3 is in the abnormal range, the control unit 4 reduces the power supply to the load compared to the power supply at the normal time (stable lighting time).

Therefore, after charging the capacitor for operating the first switching element arranged on the high potential side, in the state where the DC/AC inverter 2 starts to operate, based on the measurement obtained by the measurement unit 3 Value to determine whether there is an exception. Then, when it is determined that there is an abnormality within the determination period t12, the control unit 4 reduces the power supplied to the high-pressure discharge lamp LP1 compared to the normal power supply, thereby reducing the overcurrent flowing through the circuit, thereby suppressing Thermal stress to be applied to circuit components.

In addition, in the case where it is judged by the abnormality judging portion 4f that there is an abnormality within the judging period t12, the control portion 4 may be configured to turn off All four switching elements Q2 to Q5 constituting the DC/AC inverter 2 . In this case, the flow of overcurrent through the DC/AC inverter 2 is suppressed, and the circuit can be protected. In addition, the control unit 4 may be configured to turn off at least the two first switching elements Q2 and Q3 arranged on the high potential side when it is determined by the abnormality determination unit 4f that there is an abnormality within the determination period t12. Also in this case, the flow of overcurrent through the DC/AC inverter 2 is suppressed, and the circuit can be protected.

As in this discharge lamp lighting device, when it is determined that an abnormality has occurred within the determination period t12, the control unit 4 is preferably configured to turn off at least all the first switches disposed on the high potential side within a predetermined time period. Components Q2 and Q3.

In addition, preferably, the judgment period t12 is set to be as short as possible so that the starting performance of the high-pressure discharge lamp LP1 is not adversely affected. Furthermore, it is preferable to set the output voltage V2 of the DC/DC converter 1 according to the rated voltage of the discharge lamp (high pressure discharge lamp LP1) of the load, and in the case of a commonly used high pressure discharge lamp, it is preferable to set the output voltage Set in the range of 350V ~ 450V. In addition, preferably, the time to charge the bootstrap capacitor is set to a time to the extent that charging of the bootstrap capacitor is completed, and may be appropriately set in accordance with the capacitance of the bootstrap capacitor. In addition, preferably, the frequency at which the DC/AC inverter 2 alternates the polarity of the output voltage of the DC/DC converter 1 is set between 200˜600 Hz.

Example 2

A discharge lamp lighting device A according to Embodiment 2 will be described with reference to FIGS. 6A to 10H .

In the discharge lamp lighting device A according to this embodiment, the abnormality judgment operation at startup is different from the abnormality judgment operation at startup of the discharge lamp lighting device A according to Embodiment 1, but the circuit configuration and other operations are the same as those according to the embodiment. The circuit configuration and other operations of the discharge lamp lighting device A of Example 1 are the same. Therefore, the same reference numerals are given to the constituent elements common to the discharge lamp lighting device A according to Embodiment 1, and descriptions for these constituent elements are omitted.

6A to 6H are waveform diagrams of each unit at startup (the no-load operation mode MD1 described in Embodiment 1). 6A shows the input voltage V1 of the DC/DC converter 1 , FIG. 6B shows a signal LF1 sent from the control section 4 , and FIG. 6C shows a signal LF2 sent from the control section 4 . In addition, FIG. 6D shows the output voltage V2 of the DC/DC converter 1, and FIG. 6E shows the voltage V3 applied to the high-pressure discharge lamp LP1. In addition, FIG. 6F shows the signal LF3 sent from the control section 4, FIG. 6G shows the output current I1 flowing through the high-pressure discharge lamp LP1, and FIG. 6H shows the output current I1 generated in the resistor R4 for detecting the output current. Voltage V4.

In the present embodiment, when the supply of the DC power source E1 is started, the control section 4 starts the operation for charging the bootstrap capacitor before starting the operation of the DC/DC converter 1 . At time t11 after charging of the bootstrap capacitor is completed, control section 4 applies voltage to the load by turning on switching elements Q2 and Q5 of DC/AC inverter 2 , and then starts the step-up operation of DC/DC converter 1 . Then, until the predetermined time t12 elapses from the time t11, the abnormality judging part 4f of the control part 4 is based on the output current I1 measured by the measuring part 3 (actually, a current generated in the resistor R4 for detecting the output current). Voltage V4) to determine the presence or absence of load abnormality. In other words, abnormality determination section 4f compares voltage V4 measured by measurement section 3 with voltage Vth1 corresponding to a predetermined threshold current. Then, when the voltage V4 is equal to or higher than the voltage Vth1 (in other words, when the output current I1 is equal to or higher than the threshold current), the abnormality determination unit 4f determines that an abnormality has occurred. On the other hand, when the voltage V4 is lower than the voltage Vth1, the abnormality determination unit 4f determines that there is no abnormality. This time t12 is a judging time period for judging whether there is an abnormality in the load (for example, a short circuit or a ground fault). Here, the threshold current is set to a current value that is larger than the range of the output current I1 flowing through the high-pressure discharge lamp LP1 when the load including the high-pressure discharge lamp LP1 is normal and smaller than that in an abnormality such as a short circuit or a ground fault. the current generated at the time.

When the load is short-circuited, the load impedance is greatly lowered than the normal load impedance, so the potential difference generated between the output terminals of the DC/DC converter 1 is greatly lowered than the normal potential difference, and thus in DC The output current I1 equal to or higher than the threshold current flows between the output terminals of the /AC inverter 2 . In this case, the voltage V4 measured by the measuring unit 3 is equal to or higher than the voltage Vth1 corresponding to the threshold current. Therefore, since the voltage V4 is equal to or higher than the voltage Vth1 at time t15 within the determination period t12, the control section 4 determines that the load is short-circuited, and stops the DC/DC converter 1 and the DC/AC inverter without continuing the start-up operation. operation (time t13). In addition, a delay of time t16 occurs until the operation of DC/DC converter 1 and DC/AC inverter 2 is stopped by control unit 4 from when voltage V4 becomes equal to or higher than voltage Vth1 at time t15 . This time delay is caused by a delay in a circuit that feeds back the current value or a delay in processing performed by the control unit 4 .

On the other hand, when the load is normal, the voltage V4 measured by the measurement unit 3 is lower than the voltage Vth1 within the above-mentioned determination period t12. Therefore, since the voltage V4 is lower than the voltage Vth1, the abnormality judging part 4f judges that there is no abnormality, and the control part 4 continues the starting operation and starts and lights the high-pressure discharge lamp LP1.

As described above, also in the discharge lamp lighting device A according to the present embodiment, in the case of starting the discharge lamp, the control section 4 starts charging the bootstrap capacitor before the DC/DC converter 1 starts to operate. Then, after the charging of the bootstrap capacitor is completed, the step-up operation of the DC/DC converter 1 is started, the DC/AC inverter 2 is operated (in other words, the switching elements Q2 and Q5 are turned on), and the DC The output of /DC converter 1 is applied to high pressure discharge lamp LP1. In this state, the control section 4 sets a judging time period t12 for judging whether or not there is an abnormality based on the measurement value acquired by the measuring section 3 . Then, when the measured value measured by the measuring unit 3 is in the abnormal range, the control unit 4 reduces the power supplied to the load from the power supplied in normal state (stable lighting).

Therefore, after charging the capacitor for operating the first switching element disposed on the high-potential side, in a state where the DC/AC inverter 2 starts operating and the DC/DC converter 1 starts operating, based on The presence or absence of an abnormality is judged based on the measured value measured by the measuring unit 3 . Then, when it is determined that there is an abnormality within the determination period t12, the control unit 4 reduces the power supplied to the high-pressure discharge lamp LP1 compared to the normal power supply, thereby reducing the overcurrent flowing through the circuit, thereby suppressing Thermal stress to be applied to circuit components.

In addition, in the case where it is judged by the control section 4 that there is an abnormality within the judgment period t12, the control section 4 may be configured to turn off the constitution by setting both the signal levels of the two signals LF1 and LF2 to the low level L. All four switching elements Q2 to Q5 of the DC/AC inverter 2 . In this case, the flow of overcurrent through the DC/AC inverter 2 is suppressed, and the circuit can be protected. In addition, when it is determined by the control unit 4 that there is an abnormality within the determination period t12, the control unit 4 may be configured to turn off at least all the first switching elements Q2 and Q3 arranged on the high potential side. Also in this case, the flow of overcurrent from the DC/DC converter 1 to the DC/AC inverter 2 is suppressed, and the circuit can be protected.

As in the discharge lamp lighting device according to the present embodiment, in the case where the measurement value acquired by the measurement section 3 is in the abnormal range during the judgment period t12, preferably, the control section 4 is configured to stop the DC/DC converter 1 switching operation.

Like the discharge lamp lighting device according to the present embodiment, preferably, the control section 4 is configured to detect the presence or absence of a short circuit in the load as an abnormality based on the measurement value measured by the measurement section 3 within the determination period t12 .

Like the discharge lamp lighting device according to the present embodiment, when the control section 4 determines that there is no abnormality within the determination period t12, preferably, the drive section is configured to charge the capacitor (bootstrap capacitor) again.

As with the discharge lamp lighting device according to the present embodiment, preferably, the measurement section 3 is configured to measure the output current of the DC/DC converter 1 within the determination period t12. In this case, when the current value measured by the measurement unit 3 is equal to or greater than a predetermined threshold current, the control unit 4 determines that a short circuit has occurred in the load.

In the present embodiment, the measurement unit 3 measures the output current I1 to the load (actually, the voltage V4 proportional to the output current I1 ) within the determination period t12 . Then, when output current I1 is equal to or greater than a predetermined threshold current (in other words, when voltage V4 is equal to or greater than voltage Vth1 corresponding to the threshold current), control unit 4 determines that a short circuit has occurred in the load.

As described above, when a short circuit occurs in the load, an overcurrent flows from the DC/DC converter 1 to the load side. Therefore, by detecting an overcurrent, the control unit 4 can reliably detect a short circuit of the load by employing a simple circuit configuration. In addition, also in the discharge lamp lighting device A described in Embodiment 1, obviously, the control unit 4 can determine the presence or absence of an abnormality based on the output current measured by the measurement unit 3 .

In the above description, during the determination period t12, the control unit 4 determines the presence or absence of an abnormality based on the output current I1 to the load, but may determine the presence or absence of an abnormality based on the output voltage V3 to the load. In other words, the measurement section 3 can measure the output voltage of the DC/DC converter 1 within the determination period t12. In this case, the control unit 4 may determine that a short circuit has occurred in the load when the voltage value measured by the measurement unit 3 is equal to or less than a predetermined threshold voltage.

Here, the procedure for measuring the output voltage V3 to the load (actually, a voltage V5 proportional to the output voltage V3) using the measuring section 3 and judging an abnormality based on the measured value using the abnormality judging section 4f will be described with reference to FIGS. 7A to 7H . With or without operation. 7A to 7H are waveform diagrams of each unit at startup (the no-load operation mode MD1 described in Embodiment 1). 7A shows the input voltage V1 of the DC/DC converter 1 , FIG. 7B shows a signal LF1 sent from the control section 4 , and FIG. 7C shows a signal LF2 sent from the control section 4 . In addition, FIG. 7D shows the output voltage V2 of the DC/DC converter 1, and FIG. 7E shows the voltage V3 applied to the high-pressure discharge lamp LP1. Furthermore, FIG. 7F shows a signal LF3 sent from the control section 4 , FIG. 7G shows an output current I1 flowing through the high-pressure discharge lamp LP1 , and FIG. 7H shows a voltage V5 measured by the measurement section 3 .

As shown in FIGS. 7A to 7H , at time t11 after the charging of the bootstrap capacitor is completed, the control section 4 applies a voltage to the load by turning on the switching elements Q2 and Q5 of the DC/AC inverter 2, and then starts the DC/DC boost operation of converter 1. Then, from the time t11 until the predetermined time t12 elapses (the above-mentioned judgment period), the abnormality judgment part 4f of the control part 4 compares the voltage V5 measured by the measurement part 3 with the voltage Vth2 corresponding to the predetermined threshold voltage Compare. When the load is short-circuited, the load impedance is significantly lower than the normal load impedance, so the potential difference generated between the output terminals of the DC/DC converter 1 is significantly lower than the normal potential difference, so that the overcurrent is flows between the output terminals of the DC/AC inverter 2 . Therefore, when the output voltage V3 is equal to or less than the threshold voltage, in other words, when the voltage V5 is equal to or less than the voltage Vth2 during the determination period t12, the abnormality determination unit 4f determines that a short circuit has occurred in the load. On the other hand, when the voltage V5 is higher than the voltage Vth2, the abnormality determination unit 4f determines that there is no abnormality. In addition, the abnormality judging portion 4f judges the presence or absence of a short circuit based on the voltage value V5 at time t17 when a predetermined time elapses from transition to the judging period t12 in consideration of the rising time of the voltage V5. Here, in the case where a delay of time t18 occurs from when the short circuit is determined to occur at time t17 until the operation of the DC/DC converter 1 and the DC/AC inverter 2 is stopped, the time delay is due to the control unit 4 and the like. caused by delays in the processing performed.

As described above, in the determination period t12, when the output voltage V3 is equal to or less than the predetermined threshold voltage, in other words, when the voltage V5 measured by the measuring section 3 is equal to or less than the voltage Vth2 corresponding to the threshold voltage , the abnormality determination unit 4f of the control unit 4 determines that the load is short-circuited. In the case of a short circuit in the load, the output voltage generated in the load drops due to a large drop in load impedance, and by measuring the drop in output voltage accordingly, the control section 4 can reliably detect the load by adopting a simple circuit configuration. short circuit in the In addition, the threshold voltage is set to a voltage value lower than the voltage range including the voltage supplied to the load when the load of the high pressure discharge lamp LP1 is normal and higher than the occurrence of an abnormality such as a short circuit or a ground fault. the voltage generated in the load. In addition, also in the discharge lamp lighting device A described in Embodiment 1, obviously, the control unit 4 can determine the presence or absence of an abnormality based on the output voltage measured by the measurement unit 3 .

In addition, within the determination period t12, the abnormality determination unit 4f of the control unit 4 may determine the presence or absence of a short circuit based on both the output current to the load and the output voltage. In other words, within the determination period t12, the measurement section 3 can measure both the output current and the output voltage of the DC/DC converter 1 . In this case, when the current value measured by the measurement unit 3 is equal to or greater than a predetermined threshold current and the voltage value measured by the measurement unit 3 is equal to or less than a predetermined threshold voltage, the control unit 4 may determine that the load is A short circuit has occurred.

An operation for judging the presence or absence of abnormality based on the output current and output voltage measured by the measurement section 3 using the abnormality judging section 4 f of the control section 4 will be described with reference to FIGS. 8A to 8I . 8A to 8I are waveform diagrams of each unit at startup (the no-load operation mode MD1 described in Embodiment 1). 8A shows the input voltage V1 of the DC/DC converter 1 , FIG. 8B shows a signal LF1 sent from the control section 4 , and FIG. 8C shows a signal LF2 sent from the control section 4 . In addition, FIG. 8D shows the output voltage V2 of the DC/DC converter 1, and FIG. 8E shows the voltage V3 applied to the high-pressure discharge lamp LP1. In addition, FIG. 8F shows the signal LF3 sent from the control section 4, FIG. 8G shows the output current I1 flowing through the high-pressure discharge lamp LP1, FIG. 8H shows the voltage V5 measured by the measurement section 3, and FIG. 8I shows The voltage V4 measured by the measurement unit 3 .

As shown in FIGS. 8A to 8I , at time t11 after the charging of the bootstrap capacitor is completed, the control section 4 applies a voltage to the load by turning on the switching elements Q2 and Q5 of the DC/AC inverter 2, and then starts the DC/DC boost operation of converter 1. Then, from the time t11 until the predetermined time t12 elapses (the above-mentioned judgment period t12), the abnormality judging part 4f of the control part 4 compares the voltage V5 measured by the measuring part 3 with the voltage Vth2, and compares the measured The voltage V4 measured by the unit 3 is compared with the voltage Vth1. When the load is short-circuited, the load impedance is significantly lower than the normal load impedance, so the potential difference generated between the output terminals of the DC/DC converter 1 is significantly lower than the normal potential difference, so that the overcurrent is flows between the output terminals of the DC/AC inverter 2 .

Therefore, in the determination period t12, when the output current I1 is equal to or greater than the threshold current and the output voltage V3 is equal to or less than the threshold voltage, in other words, the voltage V4 is equal to or greater than the voltage Vth1 and the voltage V5 is equal to or less than the voltage Vth2, the abnormality determination unit 4f It was judged that a short circuit occurred in the load. On the other hand, when the voltage V4 is lower than the voltage Vth1 or when the voltage V5 is higher than the voltage Vth2, the control unit 4 determines that there is no abnormality. Here, the threshold current is set to a current value higher than the range of the output current I1 flowing through the load including the high pressure discharge lamp LP1 when the load is normal and lower than the range where such a short circuit or ground fault occurs. abnormal current flow. In addition, the threshold voltage is set to a voltage value lower than the range of the voltage (output voltage V3) generated in the load when the load including the high-pressure discharge lamp LP1 is normal, and higher than the range where a short-circuit occurs such as The voltage generated in the load when there is an abnormality such as a ground fault or ground fault.

As described above, the control section 4 determines that a short circuit has occurred in the load when the output current I1 is in the short-circuit current range and the output voltage V3 is in the short-circuit voltage range during the determination period t12. Therefore, by detecting an abnormal drop in output voltage or an overcurrent flowing through a load that occurs according to a load abnormality during a start-up operation, it is possible to reliably detect a short circuit by using a simple circuit. In addition, also in the discharge lamp lighting device A described in Embodiment 1, obviously, the control unit 4 can determine the presence or absence of an abnormality based on both the output current and the output voltage measured by the measurement unit 3 .

In addition, when the control unit 4 determines that there is no abnormality within the determination period t12, as shown in FIGS. working. Here, the control section 4 may recharge the bootstrap capacitor by setting both the signal levels of the two signals LF1 and LF2 to the high level H at the time t13 when the determination period t12 ends. In this case, the bootstrap capacitor is charged again after the end of the judgment period t12, and the first switching element Q2, which is turned on during the first period t1 of the subsequent startup mode MD2 or DC phase mode MD3, can be turned on. The connection time is maintained for a long time.

As shown in FIGS. 10A to 10H , when the control unit 4 turns on the switching elements Q2 and Q5 of the DC/AC inverter 2 within the judgment period t12, the bootstrap capacitor C6 is discharged, and the voltage VC6 at both ends thereof is discharged. decline. For this reason, the time period in which the first switching element Q2 can be turned on using the electric charge charged in the bootstrap capacitor C6 is shortened. Thus, during the period t21 from the time t13 until the startup mode MD is started, the control section 4 performs an operation of charging the bootstrap capacitor C6 by turning on the second switching elements Q4 and Q5. As described above, by recharging the bootstrap capacitor C6, charging of the charge required to turn on the first switching element Q2 during the first time period t1 of the subsequent startup mode MD2 or DC phase mode MD3 can be performed.

Therefore, even in the case of using the bootstrap capacitor C6 which does not have a large electrostatic capacity, the first switching element Q2 arranged on the high potential side can be turned on for a long time, and the circuit can be miniaturized. This can reduce the installation area.

In addition, also in the discharge lamp lighting device A described in Embodiment 1, when the abnormality judging part 4f of the control part 4 judges that there is no abnormality within the judging time period, the control part 4 may restart the operation of the bootstrap capacitor. Perform charging operation. Therefore, even in the case where the on-time is set long to prevent extinguishing when starting the operation of the DC/AC inverter 2, by recharging the bootstrap capacitor, the switching element arranged on the high-potential side can be turned off. The ON state is maintained for a long time.

Example 3

A discharge lamp lighting device A according to Embodiment 3 will be described with reference to FIGS. 11 to 13I.

The discharge lamp lighting device A according to this embodiment includes a non-isolated DC/DC converter 1 different from Embodiments 1 and 2, but the other structures and operations are the same as those of Embodiments 1 and 2. Therefore, the same reference numerals are given to the constituent elements common to Embodiments 1 and 2, and explanations for these constituent elements are omitted.

The DC/DC converter 1 includes a transformer T3 including magnetically coupled windings P3 and S3, a switching element Q1, a diode D1, and capacitors C1 and C2. The capacitor C1 is connected between both ends of the DC power supply E1 via the power switch SW1. Between both ends of the capacitor C1, the winding P3 of the transformer T3 is connected in series with the switching element Q1. One end of the winding S3 is connected to the connection point of the winding P3 and the switching element Q1, and between the other end of the winding S3 and the negative electrode of the DC power supply E1, a capacitor C2 is connected via a diode D1. The DC/DC converter 1 shown in the figure is constituted by a step-up chopper circuit, and its operation is conventionally known, so a detailed explanation for the operation is omitted. On/off of the switching element Q1 is controlled by the control unit 4, and a constant voltage obtained by boosting the input voltage is generated between both ends of the capacitor C2. Here, as an example, although a step-up chopper circuit is illustrated as the non-isolated type DC/DC converter 1 , a step-down chopper circuit or a step-up/step-down chopper circuit may also be used.

In the case where the DC/DC converter 1 is a non-isolated type, even in a state where the DC/DC converter 1 is not operating, when the load is short-circuited and the switching elements Q2 and Q5 of the DC/AC inverter 2 are turned on , the overcurrent also flows through the path indicated by the dotted line RT3 in FIG. 11 .

Therefore, also in this embodiment, the abnormality of the load is judged at the time of startup. In the case where it is determined that the load is abnormal, the operations of the DC/DC converter 1 and the DC/AC inverter 2 are stopped. Here, an operation for judging an abnormality of a load at startup will be described with reference to FIGS. 12A to 12I . 12A to 12I are waveform diagrams of each unit at startup (the no-load operation mode MD1 described in Embodiment 1). 12A shows the input voltage V1 of the DC/DC converter 1 , FIG. 12B shows the signal LF1 sent from the control section 4 , and FIG. 12C shows the signal LF2 sent from the control section 4 . In addition, FIG. 12D shows the output voltage V2 of the DC/DC converter 1, and FIG. 12E shows the voltage V3 applied to the high-pressure discharge lamp LP1. In addition, FIG. 12F shows the signal LF3 sent from the control section 4, FIG. 12G shows the output current I1 flowing through the high-pressure discharge lamp LP1, FIG. 12H shows the voltage V5 measured by the measurement section 3, and FIG. 12I shows The voltage V4 measured by the measurement unit 3 .

Also in this embodiment, when the supply of the DC power source E1 is started, the control section 4 starts the operation for charging the bootstrap capacitor before the DC/DC converter 1 starts to operate. At time t11 after charging of the bootstrap capacitor is completed, control section 4 applies voltage to the load by turning on switching elements Q2 and Q5 of DC/AC inverter 2 , and then starts the step-up operation of DC/DC converter 1 . Then, until the predetermined time t12 elapses from the time t11, the abnormality determination unit 4f of the control unit 4 based on the voltage V4 (corresponding to the output current I1) and the voltage (corresponding to the output voltage V3) measured by the measuring unit 3 The presence or absence of an abnormality in the load is judged based on the voltage V5 of the load.

In other words, the abnormality judging section 4f compares the voltage V4 measured by the measuring section 3 with the voltage Vth1 corresponding to the predetermined threshold current, and compares the voltage V5 measured by the measuring section 3 with the voltage Vth1 corresponding to the predetermined threshold voltage. voltage Vth2 for comparison. Then, when the output current I1 is equal to or greater than the threshold current and the output voltage V3 is equal to or less than the threshold voltage, in other words, when the voltage V4 is equal to or greater than the voltage Vth1 and the voltage V5 is equal to or less than the voltage Vth2, the abnormality determination unit 4f determines that the abnormality has occurred. abnormal load. On the other hand, when the voltage V4 is lower than the voltage Vth1 or the voltage V5 exceeds the voltage Vth2, the abnormality determination unit 4f determines that there is no abnormality.

When the load is short-circuited, the load impedance is significantly lower than the normal load impedance, so the potential difference generated between the output terminals of the DC/DC converter 1 is significantly lower than the normal potential difference, so that the threshold current exceeds The output current I1 of the DC/AC inverter 2 flows between the output terminals. In this case, the voltage V4 measured by the measuring unit 3 is equal to or higher than the voltage Vth1, and the voltage V5 measured by the measuring unit 3 is equal to or lower than the voltage Vth2. Therefore, since the voltage V4 is equal to or higher than the voltage Vth1 and the voltage V5 is equal to or lower than the voltage Vth2 at time t13 within the determination period t12, the control section 4 determines that the load is short-circuited, and stops the DC/DC converter without continuing the startup operation. 1 boost operation (time t13). Here, since the DC/DC converter 1 is constituted by a non-isolated type converter circuit, current continues to flow through the high-pressure discharge lamp LP1 after stopping the operation of the DC/DC converter 1 also at time t13. Thus, at the time t20 from when the operation of the DC/DC converter 1 is stopped until the predetermined time t19 elapses, with the control section 4, by setting the signal levels of the two signals LF1 and LF2 to the low level L to turn off all four switching elements Q2 to Q5 constituting the DC/AC inverter 2 . Therefore, also in the case where the DC/DC converter 1 is of the non-isolated type, current does not continuously flow through the high pressure discharge lamp LP1 as a load, and in the event of a short circuit of the load, continuous flow of the short circuit current through the circuit can be stopped.

In addition, as shown in FIGS. 13A to 13I , when it is determined that the load is short-circuited, the control unit 4 may first turn off all four switching elements Q2 to Q5 constituting the DC/AC inverter 2 at time t13, and then at time t13 t20 stops the operation of the DC/DC converter 1 . Also in this case, since the continuous flow of the short-circuit current through the circuit can be stopped, the time during which the short-circuit current flows in the circuit can be shortened compared to the protection operation shown in FIGS. stress.

On the other hand, when the load is normal, the voltage V4 measured by the measurement unit 3 is lower than the voltage Vth1 and the voltage V5 is higher than the voltage Vth2 within the above-mentioned determination period t12. Thus, since the voltage V4 is lower than the voltage Vth1 or the voltage V5 is higher than the voltage Vth2, the control section 4 determines that there is no abnormality, continues the starting operation, and starts and lights the high pressure discharge lamp LP1.

As described above, also in the case where the DC/DC converter 1 is a non-isolated type, the load abnormality judgment described in Embodiments 1 and 2 is performed, and in the case where it is judged that the load is abnormal, the DC/DC converter 1 is stopped. and the operation of the DC/AC inverter 2, whereby the overcurrent flowing through the circuit can be suppressed.

In addition, the control section 4 can determine the presence or absence of an abnormality in the load based on one of the output voltage and the output current measured by the measurement section 3, and can determine the presence or absence of an abnormality in the load by using a relative Simple circuit structure to detect load abnormality.

As with the discharge lamp lighting device according to the present embodiment described above, preferably, the DC/DC converter 1 is of a non-insulation type.

Example 4

An embodiment in which the discharge lamp lighting device A described in one of Embodiments 1 to 3 is applied to a headlamp of a vehicle will be described with reference to FIG. 14 . In other words, the headlamp according to the present embodiment includes the discharge lamp lighting device A. As shown in FIG.

The vehicle C includes high-pressure discharge lamps LP1 as left and right headlights. In addition, the vehicle C includes a discharge lamp lighting device A that lights a high-pressure discharge lamp LP1 by using a DC power source E1 as a power source. Here, the headlamp includes a high-pressure discharge lamp LP1 and a discharge lamp lighting device A. As shown in FIG.

The discharge lamp lighting device A is one of the discharge lamp lighting devices described in Embodiments 1 to 3, and the discharge lamp lighting device stops DC/DC in the case of detecting an abnormality in a load including the high pressure discharge lamp LP1. The operation of the converter 1 and the DC/AC inverter 2, thereby suppressing an overcurrent from flowing through the circuit.

In recent years, in vehicles, weight reduction and miniaturization are achieved to improve fuel efficiency, and an increase in accommodation space inside the vehicle is required to improve comfort. As a result, the engine compartment tends to be smaller.

Thus, the temperature in the engine room becomes high, and the distance between the high-temperature engine and the discharge lamp lighting device A that lights the headlamps becomes narrow, so the discharge lamp lighting device A is used in a high temperature environment.

The discharge lamp lighting device A included in the headlamp according to the present embodiment stops the operation of the DC/DC converter 1 and the DC/AC inverter 2 in the case where abnormality of the load is detected when the high-pressure discharge lamp LP1 is started. operate. Therefore, overcurrent can be suppressed from flowing through the circuit, and thermal stress to be applied to circuit components can be reduced. Therefore, a headlamp including the discharge lamp lighting device A having high robustness even when used in a high-temperature environment can be realized.

Claims (16)

1. a lighting apparatus for discharge lamp, including:

DC-DC converter, it is configured to switch over the input voltage conversion that will be inputted from DC source Become to make the magnitude of voltage needed for discharge tube lighting；

DC/AC inverter, it includes bridge circuit, in described bridge circuit, defeated at described DC-DC converter Go out connection between terminal and have the first switch element being configured at hot side and the second switch element being configured at low potential side At least one series circuit, and the direct current that described DC/AC inverter is configured to described DC-DC converter is defeated Go out to be converted into exchange output and by described exchange output supply to the load including described discharge lamp；

Drive division, it is configured at least be alternatively switched on described first switch element when stably lighting by predetermined period With described second switch element, the direct current of described DC-DC converter is exported and is converted into by making described direct current export Polarity as accessed by predetermined period alternation exchange output；

Measurement portion, it is configured to the measurement output voltage to described load and outputs current to one of lack；And

Control portion, it is configured to, in the case of the measured value measured by described measurement portion is in abnormal ranges, make to institute State supplying when electric power is compared normal of discharge lamp to reduce to the supply electric power of described discharge lamp,

Wherein, described drive division includes that capacitor, described capacitor are configured to required electric charge supply to being configured at high electricity The control electrode of described first switch element of side, position, with the feelings disconnected at the described second switch element being configured at low potential side Described first switch element is connected under condition,

In the case of described second switch element switches, described capacitor is charged, and

In the case of starting described discharge lamp, started described before described DC-DC converter proceeds by work Capacitor is charged, and described DC-DC converter and described direct current/friendship after the charging complete of described capacitor Under the state that stream inverter is operated, described control portion is provided with for coming based on the measured value measured by described measurement portion Judge to judge the time period with presence or absence of exception.

Lighting apparatus for discharge lamp the most according to claim 1, wherein, within the described judgement time period, described measurement portion is surveyed In the case of the measured value measured is in abnormal ranges, described control portion is configured to stop described DC-DC converter Handover operation.

Lighting apparatus for discharge lamp the most according to claim 1, wherein, described control portion was configured in the described judgement time In section, detect the presence or absence as the short circuit in abnormal described load based on the measured value measured by described measurement portion.

Lighting apparatus for discharge lamp the most according to claim 1, wherein, within the described judgement time period, described control portion judges For not depositing in an exceptional case, described drive division is configured to again be charged described capacitor.

Lighting apparatus for discharge lamp the most according to any one of claim 1 to 4, wherein,

Described measurement portion is configured to measure the output electric current of described DC-DC converter within the described judgement time period, with And

In the case of the current value measured by described measurement portion is more than predetermined threshold electric current, described control portion is configured to It is judged as being short-circuited in described load.

Lighting apparatus for discharge lamp the most according to any one of claim 1 to 4, wherein,

Described measurement portion is configured to measure the output voltage of described DC-DC converter within the described judgement time period, with And

In the case of the magnitude of voltage measured by described measurement portion is below predetermined threshold voltage, described control portion is configured to It is judged as being short-circuited in described load.

Lighting apparatus for discharge lamp the most according to any one of claim 1 to 4, wherein,

Described measurement portion is configured to measure the output electric current of described DC-DC converter and defeated within the described judgement time period Go out both voltage, and

It is the electricity measured by more than predetermined threshold electric current and described measurement portion at the current value measured by described measurement portion In the case of pressure value is below predetermined threshold voltage, described control portion is configured to be judged as being short-circuited in described load.

Lighting apparatus for discharge lamp the most according to any one of claim 1 to 4, wherein, sentenced within the described judgement time period In the case of breaking as occurring extremely, described control portion is configured to the most at least open configuration in the institute of hot side There is described first switch element.

Lighting apparatus for discharge lamp the most according to any one of claim 1 to 4, wherein, described DC-DC converter is The DC-DC converter of nonisulated type.

Lighting apparatus for discharge lamp the most according to claim 8, wherein,

Described measurement portion is configured to measure the output electric current of described DC-DC converter within the described judgement time period, with And

In the case of the current value measured by described measurement portion is more than predetermined threshold electric current, described control portion is configured to It is judged as being short-circuited in described load.

11. lighting apparatus for discharge lamp according to claim 8, wherein,

Described measurement portion is configured to measure the output voltage of described DC-DC converter within the described judgement time period, with And

In the case of the magnitude of voltage measured by described measurement portion is below predetermined threshold voltage, described control portion is configured to It is judged as being short-circuited in described load.

12. lighting apparatus for discharge lamp according to claim 8, wherein,

Described measurement portion is configured to measure the output electric current of described DC-DC converter and defeated within the described judgement time period Go out both voltage, and

It is the electricity measured by more than predetermined threshold electric current and described measurement portion at the current value measured by described measurement portion In the case of pressure value is below predetermined threshold voltage, described control portion is configured to be judged as being short-circuited in described load.

13. lighting apparatus for discharge lamp according to claim 9, wherein,

Described measurement portion is configured to measure the output electric current of described DC-DC converter within the described judgement time period, with And

In the case of the current value measured by described measurement portion is more than predetermined threshold electric current, described control portion is configured to It is judged as being short-circuited in described load.

14. lighting apparatus for discharge lamp according to claim 9, wherein,

Described measurement portion is configured to measure the output voltage of described DC-DC converter within the described judgement time period, with And

In the case of the magnitude of voltage measured by described measurement portion is below predetermined threshold voltage, described control portion is configured to It is judged as being short-circuited in described load.

15. lighting apparatus for discharge lamp according to claim 9, wherein,

Described measurement portion is configured to measure the output electric current of described DC-DC converter and defeated within the described judgement time period Go out both voltage, and

It is the electricity measured by more than predetermined threshold electric current and described measurement portion at the current value measured by described measurement portion In the case of pressure value is below predetermined threshold voltage, described control portion is configured to be judged as being short-circuited in described load.

16. 1 kinds of headlamps, it includes according to the lighting apparatus for discharge lamp according to any one of claim 1 to 15.