JPH10162973A - High-pressure discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-pressure discharge lamp lighting device, which is capable of surely stopping of the generation of high-voltage pulse voltage even in an abnormal condition of a timer circuit, and stopping the supply of voltage to a highpressure discharge lamp when a secondary side short circuit of an igniter arises, at a low cost. SOLUTION: A control part 2a contain a timer circuit 5A which counts a first specified time, a timer circuit 5B which counts a second specified time, a first specified value, and a second specified value smaller than the first specified value, When the output voltage of a DC/DC converter 6 is the first specified value or more after first specified time was elapsed, or the output voltage of the DC/DC converter 6 is the first specified value or more or the second specified value or less after second specified time was elapsed, the control part 2a controls so as to decrease the output of the DC/DC converter 6 and that of DC/AC converter 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high pressure discharge lamp lighting device.

[0002]

2. Description of the Related Art In general, a high-pressure discharge lamp lighting device lights a high-pressure discharge lamp such as a metal halide lamp with a low-frequency AC rectangular wave capable of avoiding an acoustic resonance phenomenon. One conventional example is shown in the circuit diagram of FIG.

This circuit comprises a high-pressure discharge lamp LP and a DC power supply E
And a DC / DC converter 6 that converts the DC power supply E into a DC / DC voltage and stably supplies the DC power supply E to the load side. A DC / AC converter 7 for conversion; an igniter IGN for applying a high-voltage pulse to the high-pressure discharge lamp LP when the high-pressure discharge lamp LP is started to cause insulation breakdown to start the high-pressure discharge lamp LP; and a DC / DC converter 6 And a DC / DC converter 6 and a DC / AC converter 7 by detecting a voltage Va through the voltage detector 8 for detecting an output voltage (hereinafter, referred to as a voltage) Va of the DC / DC converter 7. And a control unit 2b. And
When starting the high-pressure discharge lamp LP, the DC / AC converter 7
For example, a no-load secondary voltage of about 300 to 400 V is applied to the high-pressure discharge lamp LP.
It has the function of immediately shifting from glow discharge to arc discharge.

[0004] The control unit 2b transmits the voltage Va to the resistors R1 and R2.
The comparator Comp1 compares and outputs the voltage Vx divided by the reference voltage Vref1 and the reference voltage Vref1, and a first timer circuit (hereinafter, referred to as a predetermined time) T1 (for example, one second) for setting a first predetermined time (hereinafter, referred to as a predetermined time). , A timer circuit.) 5A, an AND gate AND1, which outputs an output of the comparator Comp1 and the timer circuit 5A, and an AND gate AND1.
, The DC / DC converter 6 is driven at high frequency by PW
M-controlled high-frequency oscillation circuit 3 and AND gate AND1
And a low frequency oscillating circuit 4 that controls the DC / AC converter 7 at a low frequency with a rectangular wave by receiving the output.

Hereinafter, the operation of the control unit 2b will be briefly described. The voltage Va is detected as the lamp voltage VLA by the voltage detector 8, the voltage Va is divided by the resistors R1 and R2, and the divided voltage Vx and the reference voltage Vref1 are compared with the comparator Comp.
Compare with 1. When the output of the comparator Comp1 falls below the reference voltage Vref1 within a predetermined time T1 (for example, 1 second) set by the timer circuit 5A, the igniter IG
N generates a high voltage pulse. If the voltage does not fall below the reference voltage Vref1 within a predetermined time T1 (for example, 1 second), the DC / DC converter 6 and the DC / AC converter 7 are stopped to stop the generation of the high-voltage pulse from the igniter IGN. Inadvertent generation of a high-voltage pulse can be prevented.

[0006]

However, according to the above-mentioned conventional example, if the predetermined time T1 cannot be accurately counted due to the abnormality of the timer circuit 5A, the igniter IGN outputs a high-voltage pulse regardless of the output of the comparator Comp1. In some cases, it may be difficult to stop the generation of the high-voltage pulse by the igniter IGN, and stress may be applied to the semiconductor element and the like, leading to deterioration of the device. The first problem.

As a means for solving the first problem as described above, for example, there is a means for providing another detecting means such as a temperature sensor for detecting overheating of a switching element. The second problem is that it is difficult to discriminate the abnormal state from the abnormal state, and a malfunction occurs.

Further, there is a third problem that it is difficult to stop the voltage supply to the high pressure discharge lamp LP at the time of the secondary short circuit.

The present invention has been made in view of all of the above problems, and an object thereof is to reliably stop the generation of a high-voltage pulse even when the timer circuit 5A is in an abnormal state, and to provide a secondary short circuit. It is an object of the present invention to provide a high-pressure discharge lamp lighting device capable of stopping the supply of voltage to the high-pressure discharge lamp LP at low cost.

[0010]

According to the first aspect of the present invention, there is provided a high-intensity discharge lamp and a D / A converter for converting a DC power supply voltage into a DC / DC voltage and outputting a DC voltage.
A C / DC converter, a DC / AC converter that converts a DC voltage output of the DC / DC converter into a low-frequency AC rectangular wave voltage and supplies the high-pressure discharge lamp to the high-pressure discharge lamp, An igniter to be applied; and a first timer circuit for counting a first predetermined time.
Is not less than the first predetermined value after the predetermined time elapses, DC /
A control unit that performs control for at least reducing the output of the DC converter and the DC / AC converter, wherein the control unit includes a second timer circuit that counts a second predetermined time, and a second timer circuit that counts a second predetermined time. A DC / DC converter and a DC / DC converter when the output voltage of the DC / DC converter is equal to or higher than the first predetermined value or equal to or lower than the second predetermined value even after the lapse of the second predetermined time. / AC
A control for reducing at least the output of the converter is performed.

According to the second aspect of the present invention, the second predetermined value gradually increases in accordance with the rise of the voltage across the high-pressure discharge lamp after the high-pressure discharge lamp is started. The second predetermined time is not more than the first predetermined time.

According to a third aspect of the present invention, the second predetermined time is longer as the DC power supply voltage is lower, and is shorter as the DC power supply voltage is higher.

According to the fourth aspect of the present invention, the control unit includes:
If the output voltage of the DC / DC converter is equal to or longer than a predetermined period, equal to or higher than a first predetermined value, or equal to or lower than a second predetermined value, D
At least the output of the C / DC converter and the DC / AC converter is reduced, and the first
When the value is equal to or more than the predetermined value or equal to or less than the second predetermined value, a malfunction prevention mode for stopping the generation of the high-voltage pulse is provided.

According to the fifth aspect of the present invention, the control unit includes:
The first predetermined value is reduced when the output voltage of the DC / DC converter is equal to or longer than a predetermined period, equal to or higher than a first predetermined value, or equal to or lower than a second predetermined value.

According to the invention described in claim 6, the control unit includes:
If the output voltage of the DC / DC converter is equal to or longer than a predetermined period, equal to or higher than a first predetermined value, or equal to or lower than a second predetermined value, D
The oscillation frequency of the C / AC converter is increased.

According to the seventh aspect of the present invention, the control unit includes:
After a lapse of the second predetermined time, the mode shifts to a malfunction prevention mode.

[0017]

Embodiment

(Embodiment 1) A circuit diagram of a first embodiment according to the present invention is shown in FIG. 1, and an operation waveform diagram thereof is shown in FIG.

The difference from the conventional example shown in FIG. 7 is that, instead of the control unit 2a, even when the output voltage of the DC / DC converter 6 is higher than the normal lighting maintaining voltage at the time of startup, the high-voltage pulse of the igniter IGN is used. And stop the occurrence of
A control unit 2b that can stop the circuit even when the load short-circuit state continues for a long time;
The same reference numerals are given to the same components as those of the other conventional examples, and description thereof will be omitted.

The control unit 2b controls the voltage Va (= capacitor C
A comparator Co for comparing and outputting a voltage Vx obtained by dividing the voltage Vc2) across the two terminals by resistors R1 and R2 and a reference voltage Vref1.
mp1, a comparator Comp2 for comparing and outputting the voltage Vx and the reference voltage Vref2, and a predetermined time T1 (for example, 1 second)
And a second timer circuit (hereinafter, referred to as a timer circuit) for setting a second predetermined time (hereinafter, referred to as a predetermined time) T2 (for example, 12 seconds) longer than the predetermined time T1. 5B and an OR gate OR1 that outputs the outputs of the comparators Comp1 and Comp2 in an OR manner
And the output of the comparator Comp1 and the timer circuit 5A to A
AND gate AND1 that outputs ND and OR gate OR
AND that outputs the output of the timer circuit 5B
A gate AND2, an OR gate OR2 for performing an OR output of the AND gates AND1 and AND2, and O
DC / DC converter 6 receiving the output of R gate OR2
And a low-frequency oscillation circuit 4 which receives the output of the OR gate OR2 and controls the DC / AC converter 7 at a low frequency with a rectangular wave.

In this embodiment, the DC / DC converter 6 includes a filter unit 1 for filtering the output of the DC power supply E, a capacitor C1 connected in parallel to an output terminal of the filter unit 1, and both ends of the capacitor C1. , A series circuit of the primary winding of the pulse transformer PT1 and the switching element Qo, a secondary winding of the pulse transformer PT1 having one end connected to the source potential of the switching element Qo, and a secondary winding of the pulse transformer PT1. A diode D1 having a cathode terminal connected to the other end of the next winding;
1 and a capacitor C2 connected in parallel to both ends of the secondary winding of the pulse transformer PT1. A voltage Vc2 across the capacitor C2 (hereinafter, referred to as a voltage Vc2).
Is the output voltage of the DC / DC converter 6. In the circuit shown in FIG. 1, the output voltage of the DC / DC converter 6 has a negative potential with respect to the circuit ground, but is not particularly limited. DC / AC converter 7
This is a full-bridge inverter circuit including switching elements Q1, Q2, Q3, and Q4, and a series circuit including an inductor L1 and a capacitor C3 is connected in parallel to an output terminal of the inverter circuit. An igniter IGN is connected to both ends of the capacitor C3. The igniter IGN includes a diode D2 connected in parallel across the capacitor C3,
A series circuit including a capacitor C4 and a resistor R3, a series circuit including a resistor R3, a capacitor C5, and a diode D3 similarly connected in parallel to both ends of the capacitor C3, and a series circuit including a capacitor C4 and a capacitor C5. A series circuit composed of a primary winding of the pulse transformer PT2 and a triac TR, connected in parallel to both ends of a series circuit composed of the resistors R4 and R5, The pulse transformer PT includes a trigger element SBS inserted between the connection point of R4 and the resistor R5 and the gate terminal of the triac TR, and a secondary winding of the pulse transformer PT2.
The high-pressure discharge lamp LP is connected in series to the secondary winding No. 2. When the voltage across the trigger element SBS exceeds a certain value (for example, 500 V), the trigger element SBS is turned on, and the triac TR is turned on to turn on the pulse transformer P.
A high-voltage pulse is generated in the secondary winding of T2 and the high-pressure discharge lamp L
This is applied to P.

Hereinafter, the operation of the control unit 2a will be briefly described with reference to FIG. FIG. 2 shows a first predetermined value (hereinafter, referred to as a first predetermined value).
Called voltage. ) V1 and a second predetermined value (hereinafter, referred to as a voltage) V2 having a value lower than the voltage V1.

1. The voltage Va is detected as the lamp voltage VLA by the voltage detector 8, the voltage Va is divided by the resistors R1 and R2, and the divided voltage Vx is compared with the reference voltage Vref1 by the comparator Comp1. The output of the comparator Comp1 is set to a predetermined time T1 set by the timer circuit 5A.
When the voltage becomes equal to or lower than the reference voltage Vref1 within (for example, 1 second), the igniter IGN generates a high-voltage pulse. Also,
Within a predetermined time T1 (for example, 1 second), the reference voltage Vref1
If not, the DC / DC converter 6 and DC
By stopping the / AC converter 7, the generation of the high-voltage pulse from the igniter IGN is stopped. That is, the voltage Va is changed to the predetermined voltage V1 (for example, 2
If the voltage is equal to or higher than 00 V), it is considered that the startup has failed, and the DC / DC converter 6 and the DC / AC converter 7 are stopped to stop the generation of the high-voltage pulse from the igniter IGN.

2. If the timer circuit 5A is abnormal,
When the operation is not performed, if the voltage Va is equal to or higher than the predetermined voltage V1 within the predetermined time T2, it is regarded as an abnormal state, and DC
By stopping the / DC converter 6 and the DC / AC converter 7, the generation of the high voltage pulse from the igniter IGN is stopped, that is, the circuit protection operation is performed.

3. When the voltage Va is equal to or lower than the voltage V2 (for example, 40 V) even after the predetermined time T2, it is determined that a secondary short circuit has occurred, and the DC / DC converter 6 and the DC / AC converter 7 are stopped to thereby output a high-voltage pulse from the igniter IGN. Is stopped, that is, the circuit protection operation is performed.

Here, the predetermined time T2 is equal to the lamp voltage VL.
It is necessary to set according to the rising speed of A. When power of about the rated power is applied at the start of the high-pressure discharge lamp for the first time, the predetermined time T2 needs to be set longer (for example, 1 to 5 minutes) because the rise of the lamp voltage VLA is slow. On the other hand, when the power of about twice the rated power is applied to the rise at the time of the initial start of the high-pressure discharge lamp lighting device for a vehicle, the predetermined time T2 is shortened (for example, 12 seconds) because the rise of the lamp voltage VLA is rapid. ) Must be set.

However, when the power supply voltage Vin decreases,
Since the maximum applied power is also reduced, the rising of the light flux and the rising of the lamp voltage VLA are naturally delayed. Further, it is necessary to set the predetermined time T2 and the voltage V2 in consideration of the difference in the rise of the lamp voltage VLA due to the variation of the bulb. For example, when the predetermined time T2 is 12 seconds, the voltage V2 is about 35 to 40V.

The DC / DC converter 6, DC / A
The configuration of the C converter 7, the voltage detection unit 8, and the igniter IGN may be other than that shown in FIG.
Although field effect transistors are used for the switching elements Qo and Q1 to Q4, other switching elements such as IGBTs may be used. Further, as shown in the circuit diagram of FIG. 5, a capacitor C13 may be connected to both ends of the resistor R5 to provide a delay time for generating a high-voltage pulse.

With the above configuration, even when the timer circuit 5A is in an abnormal state, the generation of the high-voltage pulse is reliably stopped, and the voltage supply to the high-pressure discharge lamp LP is stopped when the secondary circuit is short-circuited, thereby protecting the circuit. It is possible to do.

(Embodiment 2) FIG. 3 shows an operation waveform diagram of a second embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 2 is that, as shown in FIG. 3, the rising waveform of the voltage V2 is different from the rising waveform of the lamp voltage VLA when the high-pressure discharge lamp LP is first started. The voltage waveforms are substantially similar to each other, and the predetermined time T2 ≦ the predetermined time T1. The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

With this configuration, it is possible to immediately (for example, in about 3 seconds) determine a low impedance state when the light flux of the bulb rises and an abnormal state such as a secondary short circuit. That is, by immediately detecting the abnormal state, the outputs of the DC / DC converter 6 and the DC / AC converter 7 can be immediately reduced or stopped.

(Embodiment 3) FIG. 4 shows an operation waveform diagram of a third embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 2 is that, as shown in FIG. 4, the predetermined time T2 is changed in accordance with the value of the power supply voltage Vin. When the power supply voltage Vin is high, the predetermined time T2 is short,
When the power supply voltage Vin is low, the predetermined time T2 is configured to be long, and the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

For example, when the power supply voltage Vin is rated (1
(About 3 V) is set to a predetermined time T2 = about 12 seconds.
When the initial start-up is performed at the power supply voltage Vin = 8 to 9V, the rising of the lamp voltage VLA is delayed, so that the threshold value of the voltage V2 needs to be set relatively high, and the predetermined time T2 = 20 seconds.

With the above configuration, the circuit protection operation can be performed even when the impedance at the time of short circuit is relatively high.

As means for varying the predetermined time T2, for example, a means for making the charging current of the capacitor for the timer circuit proportional to the power supply voltage Vin or other means may be used. Further, the predetermined time T2 may be configured to change according to the maximum output power instead of the power supply voltage Vin.

(Embodiment 4) FIG. 6 shows an operation waveform diagram of a fourth embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 resides in that a means for avoiding malfunction due to noise and instantaneous drop of the power supply voltage is provided, and is the same as the other first embodiments. The description is omitted by giving the same reference numerals to the components.

During the rise of the luminous flux, noise as shown in FIG. 6A and an instantaneous drop of the power supply voltage occur, and the output voltage Vc2 of the DC / DC converter 6 is temporarily reduced to a predetermined range (V1 to V1). (Between V2). In order to avoid a malfunction in such a case, in the present embodiment, as shown in FIG. 6B, the upper limit value of the no-load secondary voltage output from the DC / DC converter 6 is temporarily set. 6 (for example, from 300 V to 180 V) or
As shown in (c), the frequency of the rectangular wave output from the DC / AC converter 7 is temporarily increased (for example, 40).
From 200 Hz to 200 Hz), and a mode in which a high-voltage pulse is not generated and lighting can be maintained. If the output voltage Vc2 of the DC / DC converter 6 continues to be outside the predetermined range for a certain period of time or more, it is determined that the DC / DC converter 6 and the DC / AC converter 6 are in an abnormal state.
The output of the converter 7 or the like is reduced or stopped. DC
When the output voltage Vc2 of the / DC converter 6 returns to a predetermined range within a predetermined time, the mode returns to the lighting mode again.

With the above configuration, it is possible to avoid malfunction due to noise and instantaneous drop of the power supply voltage, to prevent deterioration of the lighting maintenance performance, and to prevent inadvertent generation of a high-voltage pulse.

(Embodiment 5) A fifth embodiment according to the present invention will be described below.

The difference from the first embodiment shown in FIG. 1 is that the timer circuit 5B counts the predetermined time T2 irrespective of the output voltage of the DC / DC converter 6, and also sets the predetermined time T2 After the lapse of time, the upper limit value of the no-load secondary voltage output from the DC / DC converter 6 is reduced (for example, from 300 V to 180 V), and the DC / A
That is, the frequency of the rectangular wave output from the C converter 7 is temporarily increased (for example, increased from 40 Hz to 200 Hz), and the mode is changed to the malfunction prevention mode to prevent generation of a high-voltage pulse. , Other first
The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

[0043]

According to the first aspect of the present invention, even when the first timer circuit is in an abnormal state, the generation of the high-voltage pulse is reliably stopped, and the voltage supply to the high-pressure discharge lamp is stopped at the time of the secondary short circuit. High-pressure discharge lamp lighting device that can be provided at low cost.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, it is possible to immediately discriminate between a low impedance state when the light flux of the bulb rises and an abnormal state such as a secondary short circuit. A possible high-pressure discharge lamp lighting device can be provided at low cost.

According to the third aspect of the present invention, in addition to the effects of the first aspect of the present invention, a high-pressure discharge lamp lighting device capable of performing a circuit protection operation even when the impedance at the time of short-circuiting is relatively high is provided at low cost. Can be provided by

According to the fourth to seventh aspects of the present invention, in addition to the effects of the first aspect of the present invention, malfunctions due to noise and instantaneous drop of the power supply voltage are avoided, and deterioration of the lighting maintenance performance is achieved. And a high-pressure discharge lamp lighting device capable of preventing inadvertent generation of a high-voltage pulse can be provided at low cost.

[Brief description of the drawings]

FIG. 1 shows a circuit diagram according to the invention.

FIG. 2 shows an operation waveform diagram of the first embodiment according to the present invention.

FIG. 3 shows an operation waveform diagram of a second embodiment according to the present invention.

FIG. 4 shows an operation waveform diagram of a third embodiment according to the present invention.

FIG. 5 shows another circuit diagram according to the invention.

FIG. 6 shows an operation waveform diagram of a fourth embodiment according to the present invention.

FIG. 7 shows a circuit diagram of a conventional example according to the present invention.

[Explanation of symbols]

 2 control unit 5 timer circuit 6 DC / DC converter 7 DC / AC converter E DC power supply IGN igniter LP high-pressure discharge lamp T predetermined time V voltage

Claims (7)

[Claims] 1. A high pressure discharge lamp and a DC power supply voltage of DC / D
A DC / DC converter for performing C conversion and outputting a DC voltage, a DC / AC converter for converting a DC voltage output of the DC / DC converter into a low-frequency AC rectangular wave voltage and supplying the same to the high-pressure discharge lamp; An igniter for applying a high-voltage pulse to the high-pressure discharge lamp when the high-pressure discharge lamp is started;
A first timer circuit for counting a predetermined time, and when the output voltage of the DC / DC converter is still equal to or higher than a first predetermined value even after a first predetermined time has elapsed, the DC / DC converter and A high-pressure discharge lamp lighting device comprising: a control unit configured to control at least a decrease in the output of the DC / AC converter; wherein the control unit includes: a second timer circuit that counts a second predetermined time; A second predetermined value that is smaller than a predetermined value, and the output voltage of the DC / DC converter remains at or above the first predetermined value or at or below the second predetermined value even after a second predetermined time has elapsed. If there is, the DC
A high-pressure discharge lamp lighting device that performs control to at least reduce the outputs of a DC / DC converter and the DC / AC converter. 2. The method according to claim 1, wherein the second predetermined value gradually increases in response to a rise in a voltage between both ends of the high-pressure discharge lamp after the high-pressure discharge lamp is started, and the second predetermined time is set to a second predetermined time. 2. The high pressure discharge lamp lighting device according to claim 1, wherein the first time is not more than the first predetermined time. 3. The high-voltage discharge device according to claim 1, wherein the second predetermined time increases as the DC power supply voltage decreases and decreases as the DC power supply voltage increases. Lighting device. 4. The DC / D converter according to claim 1, wherein the output voltage of the DC / DC converter is equal to or longer than a first predetermined value or equal to or lower than a second predetermined value for a predetermined period.
When at least the outputs of the C converter and the DC / AC converter are reduced, and the output voltage of the DC / DC converter is equal to or higher than the first predetermined value or equal to or lower than the second predetermined value for a certain period or less, 4. The high pressure discharge lamp lighting device according to claim 1, further comprising a malfunction prevention mode for stopping generation of the high voltage pulse. 5. The control unit, when the output voltage of the DC / DC converter is equal to or longer than a predetermined period, equal to or higher than the first predetermined value, or equal to or lower than the second predetermined value, adjusts the first predetermined value. 5. The high pressure discharge lamp lighting device according to claim 4, wherein the lighting device decreases. 6. The DC / A converter when the output voltage of the DC / DC converter is equal to or more than a first predetermined value or equal to or less than the second predetermined value for a predetermined period.
The high pressure discharge lamp lighting device according to claim 4, wherein the oscillation frequency of the C converter is increased. 7. The high pressure discharge lamp lighting device according to claim 4, wherein the control unit shifts to the malfunction prevention mode after the second predetermined time has elapsed.