JPH097783A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE: To improve the starting property, by detecting it when a discharge lamp is put out in the period from immediately after the discharge starting of a discharge lamp, to the polarity reverse of the low frequency, carrying out the restarting operation, and lighting the discharge lamp very rapidly in the necessary and the minimum time. CONSTITUTION: This discharge lamp lighting device furnishes a pulse generating circuit 10 to generated the starting pulse of a discharge lamp 2 by utilizing the output voltage of an inverter circuit 4 and the reversing of its polarity. When the discharge lamp 2 is put out in the period from the discharge starting of the discharge lamp 2 to the time the output polarity of the inverter circuit 4 is reversed at first, the output of the inverter circuit 4 is boosted so as to charge the capacitor of the pulse generating circuit 10 to a specific voltage. Furthermore, at the point of time when the time to allow to charge the capacitor at least to a specific voltage has elapsed, the output polarity of the inverter circuit 4 is reversed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for a vehicle, and more particularly to lighting a high pressure discharge lamp used as a headlight of an automobile.

[0002]

2. Description of the Related Art FIG. 8 is a circuit diagram of a conventional vehicle discharge lamp lighting device. In the figure, 1 is a DC power supply, 2 is a discharge lamp, 3
Is a voltage conversion circuit, 4 is an inverter circuit, 5 is a current detection circuit, 6 is a voltage detection circuit, 7 is a control circuit, and 8 is a low frequency generation circuit. In the control circuit 7, 71 is a voltage control unit,
72 is a PWM control unit, S1 is a switch control signal, 74 is a target voltage generation circuit, 75 is a comparator, 76 is a timer circuit, 77 is a lighting determination circuit, and Sx is a lighting determination signal.
Further, in the voltage conversion circuit 3, Q1 is a switching element, N1 is a primary winding of the step-up / down transformer T, and N2 is its second winding.
Next winding, D1 is a diode, C1 is a capacitor, R1 is a resistor for current detection, and 91 is a drive circuit. R2
R3 is a resistor for voltage detection. Next, in the inverter circuit 4, Q2 to Q5 are switching elements, and 92 to 9
Reference numeral 5 is a drive circuit. A pulse generation circuit 10 is added to the inverter circuit 4. In this pulse generation circuit 10, D2 and D3 are diodes, R4 to R8 are resistors, C2 to C5 are capacitors, L1 is a coil, and PT1.
Is a pulse transformer, Q6 is a triac, and SBS is a trigger element.

The operation of the circuit shown in FIG. 8 will be briefly described below. The switching element Q1 performs switching operation at high frequency by the output of the control circuit 7. When the switching element Q1 is on, a current flows through the primary winding N1 of the step-up / down transformer T, and energy is stored in the transformer T.
When the switching element Q1 is turned off, this energy is released from the secondary winding N2 of the transformer T and supplied to the capacitor C1 via the diode D1. By repeating this operation, the DC power supply 1 is connected to the capacitor C.
1 is supplied with energy, and the voltage of the capacitor C1 rises. This voltage is divided by resistors R2 and R3,
The voltage is detected by the voltage detection circuit 6 and supplied to the inverter circuit 4. In the inverter circuit 4, switching elements Q2, Q5 and switching elements Q3, Q
4 is alternately turned on and off to perform a full-bridge inverter operation, switch the connection polarity of the capacitor C1, and supply a substantially rectangular wave AC voltage to the discharge lamp 2. That is, the switching elements Q2 and Q5 are on, the switching elements Q3 and Q4 are off, and the switching elements Q2 and Q5 are off and the switching element Q is off.
3, Q4 is alternately turned on to invert the output polarity of the inverter circuit 4 in a predetermined cycle. In this manner, the discharge lamp 2 is turned on by applying the boosted rectangular wave voltage.

Next, the operation of the control circuit 7 will be described. The voltage control unit 71 controls the switching operation of the switching element Q1 according to the detection value of the voltage detection circuit 6 so that the voltage sent to the load becomes the target voltage. When the power is turned on, the target voltage generation circuit 74 outputs a predetermined voltage value. The PWM control unit 72 compares the voltage value detected by the voltage detection circuit 6 with the output of the target voltage generation circuit 74,
A switch control signal S1 for controlling the duty of the switching element Q1 is output. The output of the voltage conversion circuit 3 at the time of no load becomes a predetermined no-load secondary voltage based on the predetermined voltage output of the target voltage generation circuit 74. Through the inverter circuit 4, the capacitors C3 and C4 of the pulse generation circuit 10 are both charged by polarity inversion, and the sum becomes a predetermined value, so that the trigger element SBS causes the triac Q.
6 is turned on, the capacitors C3 and C4 are discharged, and a pulse is superimposed on the load side via the pulse transformer PT1.
This pulse causes the discharge lamp 2 to start discharging. At the start of discharge, the current flowing through the resistor R1 increases rapidly, so
The output voltage of the current detection circuit 5 also sharply rises accordingly. The lighting determination circuit 77 detects the start of discharge due to the sudden increase in the output voltage of the current detection circuit 5, and sends the lighting determination signal Sx to the low frequency generation circuit 8 and the target voltage generation circuit 74. The low frequency generation circuit 8 controls the switching frequency of the inverter circuit 4 according to the lighting determination signal Sx and / or the time measured by the timer circuit 76. Further, the target voltage generation circuit 74 receives the start of discharge by the lighting determination signal Sx, and a predetermined voltage that changes with the passage of time as shown in FIG. 9 so as to quickly and smoothly raise the luminous flux. Is output.

[0005]

Immediately after the start of lighting of the discharge lamp, during the transition period from glow discharge to arc discharge,
It is known that when the polarity of the lamp current (voltage) is reversed, the discharge becomes unstable and it easily goes out. Therefore, in order to improve the starting characteristics with the circuit configuration shown in FIG. 8, in JP-A-62-26792, as shown in FIG. 10, a low frequency polarity reversal period T1 at the time of starting is constantly turned on. By providing the starting compensating means which is set to be longer than the low frequency polarity reversal period T3, the transition from glow discharge to arc discharge after the start of discharge can be performed smoothly. Moreover, in Japanese Patent Laid-Open No. 63-150895, the structure shown in FIG.
As shown in FIG. 1, by controlling the inversion of the low-frequency polarity for a predetermined time T2 immediately after the start of discharge of the discharge lamp is detected, the transition from glow discharge to arc discharge after the start of discharge is performed. I am trying to do it smoothly. In each of these conventional techniques, the starting characteristics are improved without enlarging the lighting device.

By the way, when the discharge lamp is extinguished due to the disturbance to the lighting device during the period from the start of discharge to the first polarity reversal seen in these conventional examples, it is detected and immediately restarted. It is necessary to start it and turn on the discharge lamp. However, in the above-mentioned conventional example, the polarity is not inverted for a predetermined time from immediately after the start of discharge until the polarity is inverted,
Do not restart. Therefore, it takes a longer time than necessary to turn on the discharge lamp.

The present invention has been made in view of the above points, and when the discharge lamp goes out immediately after the discharge lamp starts to discharge and before the polarity of the low frequency is inverted, this is detected. Then, the restart operation is promptly performed, the discharge lamp is turned on very quickly in the minimum necessary time, and the starting characteristics are improved.

[0008]

In the discharge lamp lighting device of the present invention, in order to solve the above problems, as shown in FIG. 1, a DC power supply 1 and a voltage connected to the DC power supply 1 are used. It has a conversion circuit 3, an inverter circuit 4 to which power is supplied from the voltage conversion circuit 3, and a closed loop composed of at least one or more capacitors, a trigger element and a transformer, and the capacitors are supplied by the voltage supply from the inverter circuit. A pulse generation circuit 1 that is charged to a predetermined voltage and that generates a pulse when a trigger element is activated by the inversion of the output polarity of the inverter circuit and the capacitor is discharged.
0, a discharge lamp 2 connected to the output terminal of the pulse generation circuit 10, and a control circuit 7 for adjusting the supply current and / or voltage to the discharge lamp 2, and an inverter circuit from the start of discharge of the discharge lamp 2. In the discharge lamp lighting device, in which the time until the first polarity inversion of the output of 4 after the discharge starts is longer than the period of the polarity inversion during steady lighting, after the discharge of the discharge lamp 2 starts,
When the extinction of the discharge lamp 2 is detected before the output polarity of the inverter circuit 4 is first inverted, the output of the inverter circuit 4 is boosted so as to charge the capacitor of the pulse generation circuit 10 to a predetermined voltage. It is characterized by. Further, according to the invention of claim 2, when the extinction of the discharge lamp 2 is detected after the discharge of the discharge lamp 2 is started and before the output polarity of the inverter circuit 4 is first inverted,
The output of the inverter circuit 4 is boosted so as to charge the capacitor of the pulse generation circuit 10 to a predetermined voltage, and the output polarity of the inverter circuit 4 is changed at least when a time sufficient to charge the capacitor to a predetermined voltage has elapsed. It is characterized by being inverted. Further, according to the invention of claim 3, in the invention of claim 2, the output of the inverter circuit 4 is boosted without changing the polarity so as to charge the capacitor of the pulse generating circuit 10 to a predetermined voltage. It is characterized by doing.

[0009]

According to the invention of claim 1, in the period from the start of discharge to the switching of the polarity reversal period during steady lighting,
When the discharge lamp goes out due to disturbance or the like, the output of the inverter circuit is boosted to a predetermined no-load secondary voltage. As a result, the capacitor of the pulse generating circuit can be charged to a predetermined value, and the state in which the capacitor can be quickly turned on can be reached.

According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the output polarity of the inverter circuit is inverted at least when a time sufficient to charge the capacitor to a predetermined voltage has elapsed. Specifically, for example, the inversion period after the discharge lamp is extinguished is made equal to the inversion period at startup. After the power is turned on, the output boosted to the no-load secondary voltage is inverted at the cycle of start-up to start the discharge of the discharge lamp and measure until a predetermined time elapses from the discharge start time. Stop flipping. When the discharge lamp is extinguished while the polarity inversion is stopped, if the discharge lamp extinguishes, return to the operation immediately after turning on the power and immediately boost the output voltage to start up. The polarity inversion operation is performed in the cycle of and the discharge lamp is turned on again. After the discharge lamp starts to discharge, when a predetermined time has passed without being extinguished, the polarity inversion cycle in the steady state is switched to the steady lighting operation.

According to the invention of claim 3, in the invention of claim 2, when the output voltage is boosted to the no-load secondary voltage,
By making the polarity the same as it was just before extinguishing, the capacitor can be charged without discharging the electric charge charged in the capacitor until the extinguishing of the discharge lamp. The capacitor can be charged up to a predetermined voltage faster. Therefore, relighting can be performed with a shorter time until polarity reversal.

[0012]

1 is a circuit diagram of a first embodiment of the present invention.
In the circuit of this embodiment, in the circuit of the conventional example shown in FIG. 8, a erasure determination circuit 79 is added to the control circuit 7, and the target voltage generation circuit 74 is controlled by the erasure determination output to return to the state at the time of startup. To do. The extinguishing determination circuit 79 detects the extinction of the discharge lamp 2 based on the change in the detection value of the current detection circuit 5 due to the change in the current flowing through the resistor R1 when the discharge lamp 2 is extinguished, and the lighting determination signal Sx of the lighting determination circuit 77 is detected. In addition to stopping the output, an extinguishing signal Sy is sent to the target voltage generating circuit 74 to notify that the discharge lamp 2 has gone out. When the extinguishing signal Sy is input, the target voltage generating circuit 74 outputs a predetermined voltage value at the time of startup regardless of the output value at that time.

The inversion cycle of the inverter circuit 4 is, as shown in FIG. 2, at the time of startup (no load) and steady lighting.
It is assumed that the cycles are predetermined periods T1 and T3, respectively, and the polarity inversion is not performed from the discharge start time t1 to the time t2 when the predetermined time T2 elapses (hereinafter referred to as a period (t1-t2)). Regarding the switching operation of these inversion periods T1 and T3 and the operation of stopping the polarity inversion, the low-frequency generation circuit receives the lighting determination signal Sx of the lighting determination circuit 77 and the output of the predetermined time measured by the timer circuit 76. 8 is what it does.

As shown in the conventional example, the pulse generating circuit 10 does not output a pulse unless the capacitor is charged to a predetermined voltage and the output polarity of the inverter circuit 4 is reversed. Therefore, when the output voltage of the inverter circuit 4 is equal to or lower than the predetermined value and the capacitor cannot be charged to the predetermined value, no pulse is output even if the polarity is reversed. When the discharge lamp 2 is extinguished due to disturbance or the like in the period (t1 to t2) after the start of discharge, the target voltage generation circuit 74 receives the turn-off signal Sy and restarts the target voltage so that the target voltage is turned on ( That is, it is set to the same predetermined value as when there is no load. As a result, the output of the inverter circuit 4 is boosted to a predetermined no-load secondary voltage, the capacitor of the pulse generating circuit can be charged to a predetermined value, and the state in which the capacitor can be quickly turned on is reached.

FIG. 3 is a circuit diagram of the second embodiment of the present invention, and FIG. 4 is a flow chart showing the operation thereof. In this embodiment, the control circuit is realized by using the microcomputer 70. The microcomputer 70 has an A / D conversion input part P5 for a detection current, an A / D conversion input part P6 for a detection voltage, and a PWM control output S1 and inverter control outputs S2 to S5. As shown in FIG. 3, when the control circuit 7 is realized by using the microcomputer 70, the flowchart of FIG. 4 shows the polarity reversal period of the inverter control outputs S2 to S5 from the time of startup to the time of steady lighting. It shows a switching operation. The first mentioned above
In the embodiment, in the period (t1-t2) shown in FIG.
When the discharge lamp 2 goes out, a predetermined unloaded secondary voltage appears at the output end of the voltage conversion circuit 3, and even if one of the capacitors (for example, the capacitor C3) is charged to a predetermined value, the polarity is reversed next. Until then, the capacitor on the side different from the charged side (for example, the capacitor C4) is not charged and the trigger is not applied, so no pulse is generated.
This also boosts the output of the inverter circuit 4 to a predetermined no-load secondary voltage, and the capacitors C3, C
It can be said that the pulse can be generated by the polarity inversion after the time required to charge one of the four to the predetermined voltage. That is, when the discharge lamp 2 is extinguished, by switching the inversion cycle to a cycle in which at least one of the capacitors C3 and C4 can be charged to a predetermined voltage, even if the discharge lamp 2 extinguishes at any point in the period (t1-t2), It is possible to reliably generate a pulse at the time of polarity inversion and quickly restart the discharge lamp 2, thereby lighting the discharge lamp 2. Therefore, in this embodiment, the inversion period after the discharge lamp 2 is extinguished is made equal to the polarity inversion period T1 at the time of startup. After the power is turned on, the output boosted to the no-load secondary voltage is inverted at the polarity inversion cycle T1 at the time of startup to start the discharge of the discharge lamp 2, and the timer circuit (from the discharge start time until the time T2 elapses). A counter built in the microcomputer) measures the value, and the inversion of the polarity is stopped during this period. When the discharge lamp 2 is extinguished during the period when the polarity reversal is stopped, and when the discharge lamp 2 extinguishes, the operation is returned to immediately after the power is turned on and the output voltage is quickly boosted. The polarity inversion operation is performed in the cycle T1 and the discharge lamp 2 is turned on again. After the discharge of the discharge lamp 2 starts, when the predetermined time T2 elapses without extinguishing, the polarity inversion cycle is switched to T3 and the steady lighting operation is started.

FIG. 5 is a flow chart showing the operation of the third embodiment of the present invention. This flowchart shows an operation when the control circuit is configured by the microcomputer 70 with a circuit configuration equivalent to that of FIG. In the present embodiment, in the above-described second embodiment, when the output voltage is boosted to the no-load secondary voltage, the polarity thereof is made the same as that immediately before the extinction of the discharge lamp 2, so that the capacitor C3 is turned on before the extinction of the discharge lamp 2.
Since the capacitor C3 (or C4) can be charged without discharging the charge charged in (or C4), the capacitor can be charged to a predetermined voltage faster than in the case where the voltage is boosted with the polarity reversed. Therefore,
It becomes possible to re-light by shortening the time until polarity reversal. In FIG. 5, T1 is a capacitor C3 (or C
4) is charged to the no-load secondary voltage with one polarity, and it is enough time to charge it to the predetermined voltage with the other polarity. T0 (<T1) is charged to either polarity. The time is sufficient to charge the capacitor C3 (or C4) in the non-existing state to either polarity to a predetermined voltage. In this embodiment, the method of switching the polarity inversion cycle is adopted. However, after the start of discharge, immediately before the predetermined time T2 elapses, for example, when (T2-T1 / 2) elapses, the discharge lamp is turned on. When it disappears, the period in which polarity inversion is not performed is extended, that is, a predetermined time T4.
The polarity may not be inverted until (> T2) passes and the capacitor of the pulse generating circuit is charged to a predetermined voltage.

FIG. 6 is a block circuit diagram showing the configuration of the essential parts of the fourth embodiment of the present invention. This circuit switches the output polarity inversion cycle in the second embodiment without using a microcomputer. The lighting determination circuit 770 compares the detected value Vla of the lamp voltage with the reference voltage E1, and the lamp voltage is the reference voltage. When the voltage is higher than that, a Low level signal indicating non-lighting is output, and when the voltage is lower than the reference voltage, High is output.
The h-level signal is output as the lighting / lighting-off discrimination signal Sd. The timer circuit 760 is L of the lighting / lighting-off discrimination signal Sd.
A timer output signal St which becomes High level upon receiving a trigger for rising from Low level to High level and becomes Low level after a lapse of a predetermined time T2 is output.
Even before the elapse of the predetermined time T2, the timer output signal St goes to the low level by inputting the falling trigger that turns the lighting / extinguishing discrimination signal Sd from the high level to the low level.

The reference oscillation circuit 81 has a timer output signal S.
When t is a high level, the inversion (oscillation) of the polarity is stopped, and when the timer output signal St is a low level, according to the value of the lighting / extinguishing discrimination signal Sd, if the lighting / extinction discrimination signal Sd is a low level, it is started. The reference oscillation signal S8 is output at a predetermined inversion cycle T1 when the lighting / extinguishing determination signal Sd is at the high level. The rectangular wave generation circuit 82 outputs rectangular wave signals S2 to S5 for controlling the switching elements Q2 to Q5 of the inverter circuit 4 with the reference oscillation signal S8 as a reference period for polarity inversion. In FIG. 7, the light-on / light-off discrimination signal S
An example of the operation timing at the time of starting d, the timer output signal St, and the reference oscillation signal S8 is shown.

In each of the above first to fourth embodiments,
Although output control is performed by voltage feedback, output control by power or current feedback or the like may be used as long as the output voltage can be reliably boosted when the output is turned off. Further, although the lighting determination and the extinction determination are performed by detecting the current or the voltage, a method such as brightness detection of the discharge lamp may be used as long as the state of the discharge lamp can be detected promptly.

[0020]

According to the invention of claim 1, in the discharge lamp lighting device provided with the pulse generating means for generating the starting pulse of the discharge lamp by utilizing the output voltage and the polarity reversal of the inverter circuit, after the discharge is started. , When the discharge lamp goes out due to disturbance or the like until the output polarity of the inverter circuit is first inverted, this is immediately detected and the output of the inverter circuit is surely boosted to generate a pulse quickly. You can create a state. Therefore, there is an effect that the time until relighting can be shortened as much as possible.

According to the second aspect of the present invention, even if the discharge lamp is extinguished at any time during the period from the start of discharge of the discharge lamp to the first polarity reversal, at least the capacitor of the pulse generating means is extinguished after extinction. By switching the polarity inversion cycle to a short cycle in which the battery can be charged to a predetermined voltage, the effect of relighting can be extremely shortened.

According to the third aspect of the present invention, when charging the capacitor of the pulse generating means to a predetermined voltage, the polarity when boosting the output voltage of the inverter circuit is set to the same polarity as when the discharge lamp goes out. As a result, the electric charge stored in the capacitor can be charged by the time of extinction without discharging, so that the time required for charging to a predetermined voltage can be shortened. Therefore, there is an effect that the time until relighting can be shortened.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is an operation waveform diagram of the first embodiment of the present invention.

FIG. 3 is a circuit diagram of a second embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the second embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the third embodiment of the present invention.

FIG. 6 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 7 is an operation explanatory diagram of the fourth embodiment of the present invention.

FIG. 8 is a circuit diagram of a conventional example.

FIG. 9 is an explanatory diagram showing an operation of a target voltage generation circuit used in a conventional example.

FIG. 10 is a waveform diagram showing a lamp voltage at the start of the conventional example.

FIG. 11 is a waveform diagram showing a lamp voltage at the time of starting in another conventional example.

[Explanation of Codes] 1 DC power supply 2 Discharge lamp 3 Voltage conversion circuit 4 Inverter circuit 5 Current detection circuit 6 Voltage detection circuit 7 Control circuit 8 Low frequency generation circuit 10 Pulse generation circuit

Claims (3)

[Claims] 1. A closed loop composed of a direct current power supply, a voltage conversion circuit connected to the direct current power supply, an inverter circuit supplied with electric power from the voltage conversion circuit, at least one capacitor, a trigger element and a transformer. Pulse generator that has a capacitor charged to a predetermined voltage by a voltage supply from an inverter circuit, and a trigger element is activated by the inversion of the output polarity of the inverter circuit to discharge a capacitor to generate a pulse;
It consists of a discharge lamp connected to the output end of the pulse generating means, and a control circuit that adjusts the current and / or voltage supplied to this discharge lamp. In a discharge lamp lighting device in which the time until polarity reversal is made longer than the cycle of polarity reversal during steady lighting, after the discharge lamp starts discharging, the discharge lamp A discharge lamp lighting device, which boosts the output of an inverter circuit so as to charge the capacitor of the pulse generating means to a predetermined voltage when the extinction is detected. 2. A closed loop composed of a DC power supply, a voltage conversion circuit connected to the DC power supply, an inverter circuit supplied with power from the voltage conversion circuit, at least one capacitor, a trigger element and a transformer. Pulse generator that has a capacitor charged to a predetermined voltage by a voltage supply from an inverter circuit, and a trigger element is activated by the inversion of the output polarity of the inverter circuit to discharge a capacitor to generate a pulse;
It consists of a discharge lamp connected to the output end of the pulse generating means, and a control circuit that adjusts the current and / or voltage supplied to this discharge lamp. In a discharge lamp lighting device in which the time until polarity reversal is made longer than the cycle of polarity reversal during steady lighting, after the discharge lamp starts discharging, the discharge lamp When the extinguishment is detected, the output of the inverter circuit is boosted so as to charge the capacitor of the pulse generating means to a predetermined voltage, and at least the time sufficient to charge the capacitor to the predetermined voltage elapses. Discharge lamp lighting device characterized by inverting the output polarity of the discharge lamp lighting device. 3. When the extinguishing of the discharge lamp is detected after the discharge lamp starts discharging and before the output polarity of the inverter circuit is first inverted, the capacitor of the pulse generating means is charged to a predetermined voltage. 3. The discharge lamp lighting device according to claim 2, wherein the output of the inverter circuit is boosted with the same polarity without changing the polarity.