JP3397004B2 - Discharge lamp lighting device - Google Patents

Description

Description: 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 a lighting device for a high pressure discharge lamp used for a headlight of an automobile. Things. 2. Description of the Related Art FIG. 5 is a circuit diagram of a conventional discharge lamp lighting device for a vehicle. 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, reference numeral 71 denotes 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 discrimination circuit, and Sx is a lighting discrimination signal.
In the voltage conversion circuit 3, Q1 is a switching element, N1 is the primary winding of the step-up / step-down transformer T, and N2 is
The next winding, D1 is a diode, C1 is a capacitor, R1 is a current detection resistor, 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
5 is a drive circuit. A pulse generating 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, PT1
Is a pulse transformer, Q6 is a triac, and SBS is a trigger element. Hereinafter, the operation of the circuit shown in FIG. 5 will be briefly described. The switching element Q1 performs a switching operation at a 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 / step-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
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 inverter circuit 4, switching elements Q2, Q5 and switching elements Q3, Q
4 turns on and off alternately 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 and the switching elements Q3 and Q4 are off, and the switching elements Q2 and Q5 are off and the switching element Q5 is off.
3 and Q4 are alternately switched on to invert the output polarity of the inverter circuit 4 at a predetermined cycle. Thus, 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 based on 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,
It outputs a switch control signal S1 for controlling the duty of the switching element Q1. The output of the voltage conversion circuit 3 under no load is 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 reversal and the sum becomes a predetermined value.
6 turns on, the capacitors C3 and C4 discharge, 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,
The output voltage of the current detection circuit 5 also rises rapidly with this. The light-on discrimination circuit 77 detects the start of discharge by abruptly increasing the output voltage of the current detection circuit 5, and sends a light-on discrimination 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. The target voltage generator circuit 74 receives the discharge by the lighting discrimination signal Sx has started to increase rapidly and smoothly up the light beam, a predetermined voltage that changes with time as shown in FIG. 6 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 the lamp easily goes out. Therefore, in order to improve the starting characteristic in the circuit configuration shown in FIG. 5 above, in JP-62-26792, as shown in FIG. 7, the steady state lighting the polarity inversion cycle T1 of the low frequency at start By providing the start compensation means which is set to be longer than the low frequency polarity inversion cycle T3, the transition from the glow discharge to the arc discharge after the start of the discharge can be smoothly performed. In JP-A-63-150895, as shown in FIG. 8 , immediately after the start of discharge of the discharge lamp is detected, the low-frequency polarity inversion is controlled so as to be stopped for a predetermined time T2. The transition from glow discharge to arc discharge after the start is performed smoothly.
In each of these conventional techniques, the starting characteristics are improved without increasing the size of the lighting device. When the discharge lamp goes out due to the influence of disturbance on 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 and turn on the discharge lamp. However, in the above conventional example, the polarity does not reverse for a predetermined time from immediately after the start of discharge until the polarity reverses,
Do not restart. As a result, it takes longer than necessary to turn on the discharge lamp. SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to detect when a discharge lamp has extinguished immediately after the discharge lamp has started discharging and before the low frequency polarity is reversed. Accordingly, the present invention aims to quickly perform a restarting operation, turn on the discharge lamp very quickly with a minimum required time, and improve the starting characteristics. In order to solve the above-mentioned problems, a discharge lamp lighting device according to the present invention is connected to a DC power supply 1 and a DC power supply 1 as shown in FIG. And a closed loop including at least one or more capacitors, a trigger element, and a transformer, and a voltage supplied from the inverter circuit. A pulse generation circuit for generating a pulse by charging the capacitor to a predetermined voltage and discharging the capacitor by inverting the output polarity of the inverter circuit to activate a trigger element;
0, a discharge lamp 2 connected to an output terminal of the pulse generation circuit 10, and a control circuit 7 for adjusting a supply current and / or a voltage to the discharge lamp 2; In the discharge lamp lighting device in which the time until the output of the output 4 first inverts the polarity after the start of the discharge is longer than the period of the polarity inversion at the time of steady lighting, after the discharge of the discharge lamp 2 starts,
When it is detected that the discharge lamp 2 has extinguished before the output polarity of the inverter circuit 4 is first inverted, the capacitor of the pulse generation circuit 10 is used to start the discharge lamp 2.
Pole output of the inverter circuit 4 from the time of extinction detection of the discharge lamp 2 so as to charge pulse to the predetermined voltage can be generated
While increasing the voltage with the same polarity without changing the characteristics , at least
Also generates a pulse to start the discharge lamp 2 with the capacitor
Sufficient time has elapsed to charge to the predetermined voltage possible
The output polarity of the inverter circuit 4 is inverted at a point in time . According to the first aspect of the present invention, in the period from the start of discharge to the switching to the polarity reversal cycle 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 , and
And when it is sufficient to charge the capacitor to the specified voltage
When the time has elapsed, the output polarity of the inverter circuit is inverted . As a result, the capacitor of the pulse generation circuit can be charged to a predetermined value, and it is possible to quickly turn on the lamp. The output of the inverter circuit
When boosting the input voltage to a no-load secondary voltage,
By setting the discharge lamp to the same as it was just before the lamp went out,
Without discharging the charge stored in the capacitor
The capacitor can be charged.
Charge the capacitor to the specified voltage faster than
Can be charged. Therefore, the time until polarity reversal is shorter
Re-lighting is possible. FIG. 1 is a circuit diagram of a first embodiment of the present invention.
In this embodiment, after the start of discharge, the polarity inversion cycle during steady lighting is performed.
When the discharge lamp goes out before switching to the period
In addition, the output of the inverter circuit is reduced to a predetermined no-load secondary voltage.
The operation of boosting will be described. The circuit of this embodiment is
In the circuit of the prior art shown in FIG. 5 , an extinguishing circuit 79 is added to the control circuit 7, and the target voltage generating circuit 74 is controlled so as to return to the state at the time of startup by the output of the extinguishing judgment. The extinguishing circuit 79 is provided for the discharge lamp 2
In response to the change in the current flowing through the resistor R1 at the time of the extinction of the discharge lamp 2, the detection of the extinction of the discharge lamp 2 is detected by the change of the detection value of the discharge lamp 2 and the output of the lit judgment signal 77 of the lit judgment circuit 77 is stopped, A light-off signal Sy is sent to the circuit 74 to notify that the discharge lamp 2 has gone out. The target voltage generation circuit 74 outputs the light-off signal Sy
Is input, a predetermined voltage value at the time of startup is output 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 at the time of steady lighting.
The polarities are not inverted during the predetermined periods T1 and T3, respectively, during a period from the discharge start time t1 to a time t2 when the predetermined time T2 elapses (hereinafter referred to as a period (t1-t2)). The switching operation of the inversion periods T1 and T3 and the operation of stopping the polarity inversion are performed by receiving the lighting determination signal Sx of the lighting determination circuit 77 and the output of the predetermined time measured by the timer circuit 76, and outputting the low frequency generation circuit. 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 not inverted. Therefore, when the output voltage of the inverter circuit 4 is lower than the predetermined value and the capacitor cannot be charged to the predetermined value, no pulse is output even if the polarity is inverted. If the discharge lamp 2 is extinguished due to disturbance or the like during the period (t1-t2) after the start of discharge, the target voltage generation circuit 74 receives the turn-off signal Sy and turns on the target voltage at the time of turning on the power ( That is, it is set to the same predetermined value as when no load is applied. As a result, the output of the inverter circuit 4 is boosted to a predetermined no-load secondary voltage, so that the capacitor of the pulse generation circuit can be charged to a predetermined value, and a state in which the lamp can be quickly turned on is achieved. FIG. 3 is a circuit diagram of a second embodiment of the present invention, and FIG. 4 is a flowchart showing the operation thereof. In this embodiment, after the start of discharge, the polarity inversion cycle during steady lighting is changed to
If the discharge lamp has fade-out in the period leading up to obtain cut conversion, Lee
Boosts the output voltage of the inverter circuit 4 to a no-load secondary voltage
At the same time, make the polarity the same as before
I will tell. In this embodiment, the control circuit is realized using the microcomputer 70. Microcomputer 7
0 indicates the detection current A / D conversion input section P5 and the detection voltage A
It has a / D conversion input section P6, 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 flow chart of FIG.
FIG . 9 shows a switching operation of the polarity inversion cycle in S5 . In this embodiment, after the start of the discharge,
During the period before switching to the polarity inversion cycle T3, the discharge lamp 2
When the output voltage of the inverter circuit 4 rises to the no-load secondary voltage when the lamp 2 goes out, the polarity thereof is set to be the same as that immediately before the lamp goes out. Since the capacitor C3 (or C4) can be charged without discharging the charged electric charge, the capacitor can be charged to the predetermined voltage more quickly than when the voltage is boosted with the polarity reversed. Therefore, re-lighting can be performed with a shorter time until polarity reversal. In FIG. 4 , T1 is a polarity inversion cycle at the time of startup .
The capacitor C3 (or C4) has been charged to a no-load secondary voltage in one polarity and is sufficient to charge it to a predetermined voltage in the other polarity, T0 (<T
1) is a time sufficient for charging the capacitor C3 (or C4), which has not been charged to either polarity, to a predetermined voltage at either polarity. Further, in this embodiment, the method of switching the polarity inversion cycle is employed. However, immediately after the predetermined time T2 elapses after the discharge starts, for example, when (T2−T1 / 2) elapses, the discharge lamp is activated. In the case of the disappearance, the period during which the polarity inversion is not performed is extended, that is, the polarity inversion is not performed until the predetermined time T4 (> T2) elapses and the capacitor of the pulse generation circuit is charged to the predetermined voltage. You may do it. [0015] As means for discriminating lighting / unlighting,
Is not limited to means that detecting the lamp current as described above,
For example, the detected value Vla of the lamp voltage is compared with a reference voltage , and when the lamp voltage is higher than the reference voltage, a low level signal indicating no lighting is turned on, and when the lamp voltage is lower than the reference voltage, a high level signal indicating lighting is turned on / off. as a discrimination signal may be used means such as output. [0016] In each embodiment described above, it is performed to output control by voltage feedback, as long as it can boost reliably output voltage during extinction, or the output control of the power or current feedback, and the like. In addition, although the lighting determination and the extinguishing determination are performed by current or voltage detection, any method such as luminance detection of the discharge lamp may be used as long as the state of the discharge lamp can be detected quickly. According to the first aspect of the present invention, there is provided a discharge lamp lighting device provided with a pulse generating means for generating a start pulse of a discharge lamp using an output voltage of an inverter circuit and inversion of polarity. After the discharge starts, when the discharge lamp goes out due to disturbance or the like during the period until the output polarity of the inverter circuit first reverses, this is immediately detected and the pulse of the inverter circuit is quickly boosted by surely boosting the output of the inverter circuit. Can be created. Therefore, there is an effect that the time until re-lighting can be shortened as much as possible.
In addition, the capacitor of the pulse generation means is charged to a predetermined voltage.
In doing so, boost the output voltage of the inverter circuit
Polarity when the discharge lamp goes out
By the time of the disappearance, it is stored in the capacitor
Can be charged without discharging the charged electric charge.
The time required for charging the battery can be shortened. Therefore,
The effect that the time until re-lighting can be shortened
is there.

BRIEF DESCRIPTION OF THE 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 circuit diagram of a conventional example. FIG. 6 is an explanatory diagram showing an operation of a target voltage generation circuit used in a conventional example. FIG. 7 is a waveform diagram showing a lamp voltage at the time of starting according to a conventional example. FIG. 8 is a waveform diagram showing a lamp voltage at the time of starting in another conventional example. [Description of Signs] 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-349586 (JP, A) JP-A-62-26792 (JP, A) JP-A-63-150895 (JP, A) JP-A-5-349586 290988 (JP, A) JP-A-4-342990 (JP, A) JP-A-4-349394 (JP, A) JP-A-6-203977 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05B 41/18-41/298

Claims (1)

(57) [Claim 1] A DC power supply, a voltage conversion circuit connected to the DC power supply, an inverter circuit receiving power supply from the voltage conversion circuit, at least one capacitor and a trigger It has a closed loop composed of an element and a transformer, the capacitor is charged to a predetermined voltage by the voltage supply from the inverter circuit, and the trigger element works by the reversal of the output polarity of the inverter circuit to discharge the capacitor and generate a pulse. Pulse generating means,
It comprises a discharge lamp connected to the output terminal of the pulse generating means, and a control circuit for adjusting a supply current and / or a voltage to the discharge lamp. In a discharge lamp lighting device in which the time until polarity reversal is longer than the period of polarity reversal during steady-state lighting, after the discharge lamp discharge starts, the discharge lamp When the disappearance is detected, the capacitor of the pulse generating means is released.
The output of the inverter circuit is turned off so that the lamp is charged to the predetermined voltage capable of generating a pulse for starting the lamp.
If the voltage is boosted with the same polarity without changing the polarity after detection
In addition, at least start the discharge lamp with the capacitor
When it is sufficient to charge to the predetermined voltage that can generate a pulse
When the time has elapsed, the output polarity of the inverter circuit is inverted.
A discharge lamp lighting device characterized in that: