JPH11135287A - Lighting device for high intensity discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To build up intensity at a high speed by fitting build-up characteristics to characteristics of a high intensity discharge lamp, in a lighting device for a high intensity discharge lamp. SOLUTION: Power supply to a high intensity discharge lamp 9 is controlled by pulse width switching control of FET2. As for the switching control of FET2, an instantaneous current and an instantaneous voltage of the high intensity discharge lamp are detected, an instantaneous power is calculated by inputting these detected signals in a multiplier provided in a control circuit 5, and the control is carried out while this instantaneous power signal is successively compared with a power reference of a correction function. The power reference of the correction function comprises an added signal of a correction signal activated from when a power source is thrown and a correction signal making use of a charging curve of a capacitor. In addition, the correction function is set as not to generate an excessive current when lighting the lamp again after once turning it off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a high-intensity discharge lamp such as a metal halide lamp, and more particularly to a lighting device for a high-intensity discharge lamp having a characteristic in which luminance rises at high speed after lighting.

[0002]

2. Description of the Related Art A headlight lamp for a vehicle is required to have a bright and highly visible light source for safe driving at night or in bad weather such as rain and fog. At the same time, recent automobiles are equipped with many electronic devices, the DC current supplied from the battery is increasing year by year, and from the viewpoint of energy saving,
Lamps with low power consumption are required. As a lamp satisfying these requirements, a high-intensity discharge lamp such as a metal halide lamp has attracted attention.

However, a normal metal halide lamp requires a waiting time of about several minutes to reach a steady brightness after being turned on. There was a problem with the application of. To solve this problem, as described on page 88 of the “Research and Investigation Committee Report on Light Sources for Information Equipment” issued by the Illuminating Engineering Institute of Japan in 1997, automotive lamps should be filled with xenon gas to accelerate startup. Thus, light emission immediately after lighting is secured.

[0004]

The condition is that a large amount of electric power is supplied at the time of starting in order to quickly raise the brightness. Conventionally, in order to control the power supply, a method of calculating the elapsed time since the lighting and the time when the light was turned off, and taking measures such as controlling the power supply to the high-intensity discharge lamp, has been taken.
The control was complicated and required a microcomputer for time measurement and power control. Whenever the type of the high-intensity discharge lamp changes, the microcomputer program must be rewritten each time, and there is a problem that it is complicated and time-consuming. Further, in the case of microcomputer control, the electric power becomes a digital amount and changes gradually, and in some cases, it may feel unsightly. SUMMARY OF THE INVENTION It is an object of the present invention to provide a lighting device for a high-intensity discharge lamp, which has characteristics that can automatically respond to the type of a lamp and that the rise of the brightness at the time of startup is made faster.

[0005]

Means for Solving the Problems The present invention enables a high-intensity discharge lamp to be started at a high speed by combining a plurality of time constant circuits, and can easily cope with a change in the bulb. . The present invention measures an instantaneous current and an instantaneous voltage of a high-intensity discharge lamp, calculates an instantaneous power value by multiplying the instantaneous current signal and the instantaneous voltage signal, and converts the instantaneous power value to a predetermined power reference value. Controlling the power supplied to the high-intensity discharge lamp as compared with the first power reference for increasing the power reference value according to the voltage of the high-intensity discharge lamp. Means for correcting the value, and a second power for raising the power reference value once by a capacitor charging circuit at the start of voltage supply to the high-intensity discharge lamp or at power-on, and reducing this rise by a predetermined time constant. It comprises a reference value correcting means.

A lighting device for a high-intensity discharge lamp having the following configuration of the power reference value instead of the configuration of the power reference value in the above means is also proposed. That is, the configuration of the power reference value is: first power reference value correction means for increasing the power reference value according to the voltage of the high-intensity discharge lamp; At power-on, the power reference value is changed from the steady value by the capacitor charging circuit.
A second power reference value correcting means for temporarily increasing the power by about 30% to about 80% and reducing the amount of increase by a predetermined time constant; and a power supply when starting or supplying power to the high-intensity discharge lamp. The reference value is temporarily increased by 30% to 80% from the steady value by the capacitor charging circuit, and this increase is reduced by a predetermined time constant. This time constant circuit is used when the power supply to the high-intensity discharge lamp is stopped. A third power reference value correcting means for immediately resetting, and at the time of starting voltage supply to the high-intensity discharge lamp or turning on the power, the power reference value is once steeply increased by about 50% to 150% from the steady value by a capacitor charging circuit. And a fourth power reference value correcting means for increasing the amount of increase, reducing the increase by a predetermined charge time constant, and resetting the increase by a predetermined discharge time constant.

[0007]

[Action] When examining the characteristics of the tube of the high-intensity discharge lamp, the lamp voltage immediately after the lighting of the xenon-filled automotive lamp is several tens of volts. Drops to bolts. Thereafter, the mercury in the lamp evaporates, and the lamp voltage increases as the tube pressure increases. At this time, the luminance increases with a delay with respect to the increase in the lamp voltage. By performing power control corresponding to this lamp characteristic, high-speed start-up becomes possible.
That is, control corresponding to the terminal voltage of the lamp and control corresponding to the time delay are performed. Specifically, the time required for xenon to be activated (depending on the current flowing in an automobile lamp, but 0.5 seconds or less as an example) is approximately three times the electric power since the lamp voltage is relatively high, and sufficient electric current is required. sink,
When the voltage drops and the current becomes too large, the current is limited to about 5 to 7 times the steady value. As the luminance increases over time, the power supplied to the lamp is reduced. When the time constant for reducing this power is changed from 10 seconds to 30 seconds, the steady power is reached in about 1 minute, and the brightness reaches within ± 10% of the steady value within a few seconds after lighting, and there is an increase or decrease within this range. Keep a constant value.

On the other hand, it is often the case that a high-intensity discharge lamp is once turned off and then immediately turned on again. In this case, when the above-described power control is performed, there are problems that the surroundings are adversely affected, such as being too bright and too dazzling, and that the life of the lamp is shortened. Also, if you want to turn on immediately after turning off,
If a current corresponding to the lamp voltage is used without correcting the power, the current will be too small. For example, if the voltage is 80 V at a lamp power of 35 W, the lamp current will be about 0.44 A and the arc discharge cannot be maintained, causing the problem of extinguishing. Occurs. In addition, the lamp internal pressure decreases with the lamp extinguishing time, and the voltage immediately after lighting also decreases. After several tens of seconds, the pressure in the lamp tube is still high, but the voltage almost returns to the initial value. It takes several hours at room temperature in the dark to be exactly the same.

Therefore, at the time of re-lighting after turning off, it is necessary to supply a lamp current capable of reliably maintaining arc discharge, and to further change the power at the time of re-lighting according to the time of turning off.

[0010] Due to this control, at the time of re-lighting,
Supply 1.5 to 2 times the power and reduce it with a time constant of 0.5 to 2 seconds. The time constant circuit for re-lighting needs to be operated even when the lamp extinguishing time is extremely short, such as about 1 second, and is reset immediately after detecting the extinguishing.

Further, as described above, since the lamp voltage due to relighting after returning to light several tens of seconds returns to a substantially steady value, the discharge time constant for resetting the fourth power correction means is set to 10 seconds to 30 seconds. The reset is completed in about one to one minute from the second, and the rising is the same as the normal lighting. Further, by using the time constant circuit, it is possible to supply power that is almost suitable for re-lighting during reset.

[0012]

FIG. 1 shows a main circuit of an example of an embodiment of a lighting device for a high-intensity discharge lamp according to the present invention. In the figure, a main power supply 1 is connected to both ends of a primary winding of a transformer 3 and a main current terminal of an FET 2 serving as a switching element. The FET 2 is on-off controlled at a high frequency by a control circuit 5 connected to its gate. The control circuit 5
Power is supplied by the control circuit power supply circuit 4. It is rectified by the rectifier circuit 6 connected to the secondary winding of the transformer, and is further converted into a rectangular wave in the switching circuit 7.
This rectangular wave is supplied to the high-intensity discharge lamp 9 via the igniter 8. The igniter 8 gives a trigger waveform when the high-intensity discharge lamp 9 is started.

Each terminal of the control circuit 5 has a terminal A
Is connected to the gate of the FET 2, the terminal B is connected to one end of the rectifier circuit 6 which is a point proportional to the voltage of the high-intensity discharge lamp 9, and the terminal C is a resistor which is a point proportional to the current of the high-intensity discharge lamp 9. The terminal D is connected to the common line of the circuit, and the terminal E is connected to the + terminal of the power supply circuit 4 for the control circuit. The terminal F is connected to an operation signal when the high-intensity discharge lamp 9 is turned on.

FIG. 2 is a diagram showing details of the control circuit 5 in this embodiment. In FIG. 2, terminals A,
B, C, D and E respectively correspond to the terminals of the same reference numerals in FIG. The control circuit 5 is roughly divided into a first power reference value correction means 510 and a second power reference value correction means 520.
A third power reference value correcting means 530, a fourth power reference value correcting means 540, a multiplier 550, a start signal control circuit 560, an error amplifier circuit 570, a current limiting circuit 580,
And a pulse width modulation circuit 590.

The multiplier 550 includes a high-intensity discharge lamp 9
Performs the function of calculating the instantaneous power signal. The voltage signal at terminal B and the current signal at terminal C are sent to multiplier 550, and the multiplied output signal is sent to the − input terminal of operational amplifier 571.
For the multiplier 550, it is convenient to use a widely used integrated circuit, but the multiplier 550 may be formed by combining a plurality of operational amplifiers.

The error amplifier 570 includes an operational amplifier 571 and resistors 571, 572, 573, 574, 575, and the like. In the error amplifier circuit 570, the instantaneous power signal from the multiplier 550 is divided by a resistor 574 and a resistor 573 to an appropriate value and sent to the-input terminal of the operational amplifier 571. The voltage from the terminal E is connected to the resistor 576 and the resistor 572.
And is supplied to the + input terminal of the operational amplifier 571. A feedback resistor 575 is connected between the output terminal and the − input terminal of the operational amplifier 571.

The pulse width modulation circuit 590 includes an operational amplifier 57
In response to the output signal of (1), a required pulse width modulation output signal is sent to terminal A. The current signal at the terminal C is connected to the + input terminal of the comparator 581 of the current limiting circuit 580, and the-input terminal thereof is connected to the reference power supply 582. It operates to limit or stop the output of.

In the configuration described above, the instantaneous power value, which is the product of the instantaneous voltage of the high-intensity discharge lamp 9 and the detected value of the instantaneous current, and the power reference value, which is the voltage across the resistor 572, are error-amplified. The pulse width modulation circuit 590 operates so that they are equal as compared by the circuit 570.

In the above description of the configuration, the power reference value correcting means has been described, but the following description will include the power reference value correcting means.

The first power reference value correction means 510 includes an operational amplifier 511, a reference voltage 514 connected between its + input terminal and a common line, and a feedback connected between the − input terminal and the output terminal. , A resistor 515 and a diode 516 connected in series to the output terminal. The first power reference value correction means 510 starts operation when the terminal voltage of the high-intensity discharge lamp 9 falls below the normal operating range including the variation, and as the voltage of the high-intensity discharge lamp 9 decreases, the power reference value decreases. Value. A diode 516 is inserted so as not to affect the reference value when the voltage of the high-intensity discharge lamp 9 rises.

Next, the activation signal control circuit 560 will be described. When the high-intensity discharge lamp 9 is turned on, the start signal control circuit 560 converts the lighting operation signal appearing at the terminal F into a second power reference value correction means 520 and a third power reference value correction means 530. This is a circuit that is commonly provided to the fourth power reference value correction means 540. As for the configuration, the gate logic circuit 561 and the diode 568
Resistor 562 and resistor 563 individually connected in series via
And a resistor 564 and a diode connected to its input terminal
565 and a resistor 567.

The second power reference value correction means 520 issues an operation command to the lighting device 10, changes the level of the operation start signal at the terminal F from L to H, and changes the output level of the gate logic circuit 561 from H to H → When it becomes L, the pnp transistor 521 is turned on to increase the reference voltage, and the increase in the reference value is reduced by the time constant of the capacitor 522 and the resistor 523. The reset of the time constant circuit is performed via the diode 524.
Therefore, although the discharge time constant is almost the same as the charge time constant, a short time after the power is turned off and the discharge lamp 9 is turned off,
Residual charges of the control circuit power supply 4 remain at the terminal E, and the time constant circuit is not reset. Therefore, the reset circuit does not operate when the power is turned off for a short time of about 1 second or less.

The third power reference value correcting means 530 issues an operation command to the lighting device 10, the level of the operation start signal at the terminal F changes from L to H, and the output level of the gate logic circuit 561 changes from H to H → When it becomes L, the transistor 531 is turned on to increase the reference voltage, and the rise of the reference value is reduced by the time constant of the capacitor 532 and the resistor 533. This time constant circuit is reset when the level of the operation start signal of the lighting device 10 is H.
→ L, the operation of the lighting device 10 is stopped, and at the same time, the operation is performed via the diode 564, the diode 534, and the resistor 565.

The fourth power reference value correction means 540 issues an operation command to the lighting device 10, the level of the operation start signal at the terminal F changes from L to H, and the output level of the gate logic circuit 561 changes from H to H → When it becomes L, the transistor 541 is turned on to increase the reference voltage, and the rise in the reference value is reduced by the time constant of the capacitor 542 and the resistor 543. The time constant circuit is reset via the resistor 544, and the reset time constant is determined by the value of the resistor 544 and the value of the capacitor 542. Note that the value of the resistor 544 is sufficiently larger than the value of the resistor 543 and has little effect when the transistor 541 is turned on.

FIG. 3 shows a first power reference value correcting means 51.
Here is an example of the characteristic of 0 In the figure, the horizontal axis represents the percentage value of the voltage applied to the high-intensity discharge lamp, and the vertical axis represents the correction value of the first power reference value correction unit 510. In the example shown in this figure, when the applied voltage value is low, the correction value on the vertical axis is about + 70%, and the ratio of the applied voltage is 20%.
Above this, it falls linearly, and above about 70% of the applied voltage, the correction value becomes an asymptote of zero. However, the curves of these correction values act as addition values to 100% of the original power reference value.

For each of the above correction values, the following constants are set as preferred embodiments.

The time constant (related to the capacitor 522 and the resistor 523) of the second correction means 520 is set to 0.2 seconds to 0.5 seconds.

The time constant (related to the capacitor 532 and the resistor 533) of the third correction means 530 is set to 1 second to 5 seconds.

The time constant (related to the capacitor 542 and the resistor 543) of the fourth correction means 540 is set to approximately 5 seconds to 30 seconds.

The time constant of the fourth correction means and the reset circuit constant (related to the capacitor 542 and the resistor 544) is set to approximately 30 seconds to 120 seconds.

As an operation setting, the total of the correction values of the first to fourth correction means is set to 200% or more, and the power supplied to the high-intensity discharge lamp at the time of starting is set to about three times more than the steady state, and the start-up is performed. As soon as possible, when the supply voltage drops or the output short-circuits and other accidents, the current increases significantly.
Approximately 7 times, to prevent the life of the high-intensity discharge lamp and the enlargement of the ballast.

FIG. 4 shows an example of the characteristics of the second, third, and fourth power reference value correcting means. The horizontal axis represents the elapsed time after the application of the voltage to the high-intensity discharge lamp, and the vertical axis represents the percentage value of the second, third, and fourth power reference value correcting means. The second correction value (2) is + 40% at the highest value,
The correction value (3) is + 30% at the maximum value, the fourth correction value (4) is + 70% at the maximum value, and the sum of (2) + (3) + (4)
Is a + 140% correction value. In each case, the respective values show the highest values immediately after the start of the operation, and thereafter gradually decrease to approach the asymptote zero.

The correction value of the first power reference value shown in FIG. 3 and the correction values of the second, third, and fourth power reference values shown in FIG. 4 and 100% of the original power reference value The added value is supplied to the + input terminal of the operational amplifier 571, and power having a value that is always equal to the power reference value of the full addition is supplied to the high-intensity discharge lamp 9.

FIG. 5 shows start-up characteristics when the high-intensity discharge lamp is cold. Immediately after this startup, the power reference value is 300
%, And then gradually descends in about 5 seconds, and reaches a rating of 100% after several tens of seconds. A current flows through the high-intensity discharge lamp according to the characteristic of the power reference value. The light output reaches almost 100% in 3 to 5 seconds.

FIG. 6 shows an operation when the high-intensity discharge lamp being lit is once turned off and then turned on again. When the light is turned on one second after the light is turned off, the maximum current value is suppressed to 130%. 5
When the light is turned on again after seconds, the maximum current value is suppressed to 150%, and after 10 seconds, it is suppressed to 180%.

FIG. 7 is a diagram showing another embodiment of the control circuit 5. The second correction means does not use a transistor, but includes only a resistor and a capacitor. The start of operation of the second power reference value correcting means is not received from the start signal control circuit 560, and the operation is performed simply when the power is turned on, thereby simplifying the configuration and achieving economy. Similarly, this simplified configuration can be used for the third and fourth power reference value correcting means.

FIG. 8 is a partial view showing another embodiment of the third power reference value correcting means 530 in the control circuit 5.
This circuit has the same configuration as the circuit shown in FIG. 2 in that the charging characteristic of the capacitor 532 is used, but the transistor
Resistor 535, capacitor 532 and resistor on base side of 531
533, and the charging characteristic of the time constant circuit is current-amplified by the transistor 531 to constitute the third power reference value correcting means 530. This circuit utilizes the current amplifying action of the transistor, and therefore, even when the resistance value is increased, especially when the time constant is lengthened, the output impedance can be kept low and more stable operation can be achieved. There are advantages.
Similarly, this configuration can be used for the second power reference value correction means 520 and the fourth power reference value correction means 540.

In the embodiment of the present invention, the multiplier 55
For the configuration using 0, practically, an adding means can be used instead of the multiplying means. In other words, since the combination of the current value and the voltage value, which is the operating point where the correction of the power reference value acts, is near one point, it is necessary to set a coefficient for the combination of the current and the voltage corresponding to this operating point. As a result, a similar operation result can be obtained. When expressed by mathematical formulas, a and b are coefficients, x is a voltage value, and y is
Is a current value, the condition is that the following equation is satisfied.

Ax + by = ax · by

That is, it is possible to set the coefficients a and b such that this equation holds, and in that state, it is possible to approximately realize the operation of the present invention.

The lighting device for a high-intensity discharge lamp according to the present invention performs the same control not only for a vehicle but also for a high-intensity discharge lamp used for, for example, an OHP or a projector television, and starts up quickly. Becomes possible.
In this case, a change such as suppressing the electric power to about twice or the like may be performed unless a high speed as required for an automobile is required.

[0042]

Since the present invention has the above-described features, the brightness of the high-intensity discharge lamp can be reduced to 90% or more of the steady state in 3 to 5 seconds from the time of turning on the power when the high-intensity discharge lamp is turned on. Can be launched. Since the lamp is controlled based on the instantaneous current and voltage of the lamp, it does not affect the lighting characteristics even when the lamp type is changed or the power supply voltage fluctuates. Obtainable. In addition, since the supply current to the high-intensity discharge lamp is continuously controlled, the luminance is continuous and the light source has high quality.

[Brief description of the drawings]

FIG. 1 shows a main circuit of an example of an embodiment of a lighting device for a high-intensity discharge lamp according to the present invention.

FIG. 2 shows a control circuit in the lighting device for a high-intensity discharge lamp according to the present invention.

FIG. 3 shows characteristics of a first power reference value correcting means.

FIG. 4 shows characteristics of second, third, and fourth power reference value correcting means.

FIG. 5 shows starting characteristics when the high-intensity discharge lamp is cold.

FIG. 6 shows an operation when the high-intensity discharge lamp being lit is once turned off and then turned on again.

FIG. 7 shows another embodiment of the control circuit.

FIG. 8 is a partial view showing another embodiment of the power reference value correcting means in the control circuit.

[Explanation of symbols]

1. Main power supply 2. FET 3. Transformer 4.
Power supply circuit for control circuit 5 control circuit 6 rectifier circuit 7 switching circuit 8 igniter 9 high-intensity discharge lamp 10 lighting device 510 ... first power reference value correction means 520 ... second power reference value Correction means 530 ... Third power reference value correction means 540 ... Fourth power reference value correction means 550 ... Multiplier 560 ... Start signal control circuit 570 ... Operational amplifier 580 ... Current limiting circuit 590 ...
Pulse width modulation circuit

Claims (4)

[Claims] 1. A lighting device for quickly raising the brightness of a high-intensity discharge lamp, comprising: means for measuring an instantaneous current of the high-intensity discharge lamp; means for measuring an instantaneous voltage; Means for calculating the instantaneous power value by multiplying the output signal of the means and the instantaneous voltage measuring means, and comparing the instantaneous power value with a predetermined power reference value to determine the power supplied to the high-intensity discharge lamp. A lighting device to be controlled, the power reference value comprising: first power reference value correction means for increasing the power reference value according to the voltage of the high-intensity discharge lamp; A second power reference value correcting means for raising the power reference value once sharply by a capacitor charging circuit at the start of voltage supply or at power-on, and reducing this rise by a predetermined time constant. Lighting device for high-intensity discharge lamps. 2. A lighting device for quickly raising the brightness of a high-intensity discharge lamp, comprising: means for measuring an instantaneous current of the high-intensity discharge lamp; means for measuring an instantaneous voltage; Means for calculating the instantaneous power value by multiplying the output signal of the means and the instantaneous voltage measuring means, and comparing the instantaneous power value with a predetermined power reference value to determine the power supplied to the high-intensity discharge lamp. A lighting device to be controlled, the power reference value comprising: first power reference value correction means for increasing the power reference value according to the voltage of the high-intensity discharge lamp; At the start of voltage supply or when power is turned on, the power reference value is changed from the steady value by the capacitor charging circuit.
A second power reference value correcting means for temporarily increasing the power by about 30% to about 80% and reducing the amount of increase by a predetermined time constant; and a power supply when starting or supplying power to the high-intensity discharge lamp. The reference value is temporarily increased by 30% to 80% from the steady value by the capacitor charging circuit, and this increase is reduced by a predetermined time constant. This time constant circuit is used when the power supply to the high-intensity discharge lamp is stopped. A third power reference value correcting means for immediately resetting, and at the time of starting voltage supply to the high-intensity discharge lamp or turning on the power, the power reference value is once steeply increased by about 50% to 150% from the steady value by a capacitor charging circuit. A lighting device for a high-intensity discharge lamp, comprising: a fourth power reference value correcting means for raising the power, reducing the rise with a predetermined charging time constant, and resetting the power with a predetermined discharging time constant. 3. The time constant of the capacitor charging circuit according to the second power reference value correcting means according to claim 2 is set to approximately 0.2.
From 0.5 to 0.5 seconds, the time constant of the capacitor charging circuit according to the third power reference value correcting means is set to 1 second or more and 5 seconds or less, and the capacitor charging circuit according to the fourth power reference value correcting means. A time constant of about 5 seconds to 30 seconds and a capacitor discharge circuit time constant of the fourth power reference value correcting means of about 30 seconds to 120 seconds. Lighting device. 4. The total value of the peak values of the power reference values according to claim 2 or 3 is set to about 200% to 250%, and the maximum value of the current to the high-intensity discharge lamp is determined as the steady-state current. A lighting device for a high-intensity discharge lamp, comprising current limiting means for limiting the current to about five to seven times.