JP3793339B2 - High-intensity discharge lamp lighting device - Google Patents

Description

[0001]
BACKGROUND 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 that the luminance rises at high speed after lighting.
[0002]
[Prior art]
Automotive headlight lamps require a light source that is bright and highly visible for safe driving at night and in bad weather such as rain and fog. At the same time, many automobiles are equipped with recent electronic devices, and the direct current supplied from the battery increases year by year, so that a lamp with low power consumption is required from the viewpoint of energy saving. High-intensity discharge lamps such as metal halide lamps are attracting attention as lamps that satisfy these requirements.
[0003]
However, since normal metal halide lamps require a few minutes to reach steady brightness after they are turned on, they may cause problems when entering tunnels or driving cars at night. Had a problem. To solve this problem, xenon gas is used in the automotive lamp to accelerate the start-up, as described on page 88 of the “Survey Committee on Information Equipment Light Sources” published in 1997 by the Lighting Society of Japan. The light emission immediately after lighting is ensured.
[0004]
[Problems to be solved by the invention]
In order to increase the brightness at high speed, it is necessary to supply a large amount of power at the start. In order to control the supply power, conventionally, the time elapsed since lighting and the time when it was turned off are calculated, and measures such as controlling the supply power to the high-intensity discharge lamp are taken. A microcomputer was required for time measurement and power control. Each time the type of high-intensity discharge lamp is changed, the microcomputer program must be rewritten, which is complicated and time-consuming. Furthermore, in the case of microcomputer control, the electric power becomes a digital amount and changes in stages, and in some cases, it may feel unsightly. It is an object of the present invention to provide a lighting device for a high-intensity discharge lamp that has a characteristic that can automatically cope with the type of tube and that the rise in luminance at the time of startup is increased.
[0005]
[Means for Solving the Problems]
The present invention enables a high-intensity discharge lamp to be started at high speed by combining a plurality of time constant circuits each connected in series with a resistance means that generates a power reference value, and can easily cope with changes in the tube. It is what I did. The first invention is a means for measuring an instantaneous current of a high-intensity discharge lamp, a means for measuring an instantaneous voltage, and multiplying output signals of these instantaneous current measuring means and instantaneous voltage measuring means to obtain an instantaneous power value. Multiplying means for calculating, an operational amplifier for receiving the instantaneous power value at one input terminal and a power reference value at the other input terminal and calculating them, and an output signal from the operational amplifier as a pulse width modulation signal In a lighting device for a high-intensity discharge lamp, the control circuit comprising a control circuit comprising a pulse width modulation circuit that outputs the control circuit, and controlling the switching element by the control circuit to control the power supplied to the high-intensity discharge lamp. includes a resistance means for producing said power reference value is connected to the other input terminal of the operational amplifier, a series-connected compensation means to the resistance means, said high intensity discharge lamp Depending on the voltage, and means for correcting the first power reference value to increase the power reference value for revealing the resistance means, the first time constant circuit comprising a series-connected capacitor and a resistor to said resistance means The power reference value is once sharply increased by a current flowing through the first time constant circuit at the start of voltage supply to the high-intensity discharge lamp or when the power is turned on, and the increase is predetermined. there is provided a lighting device with high intensity discharge lamp, characterized in that it comprises a correction means of the second power reference value to reduce a time constant of.
[0006]
According to a second aspect of the present invention , in the first aspect of the present invention, the value by which the second power reference value correction means increases the power reference value once sharply is 30% to 80% higher than the steady value. An electric lighting device is provided. According to a third aspect of the present invention, in the second aspect of the present invention, correction means having a second time constant circuit comprising a capacitor and a resistor connected in series to the resistance means, wherein voltage supply to the high-intensity discharge lamp is started. When the power is turned on or when the power is turned on, the power reference value is suddenly increased 30% to 80% higher than the steady value, and the increase is decreased by a predetermined time constant, and the power supply to the high-intensity discharge lamp is stopped. There is provided a lighting device for a high-intensity discharge lamp comprising a third power reference value correcting means that is sometimes reset immediately . According to a fourth aspect of the present invention , there is provided a correction means having a third time constant circuit comprising a capacitor and a resistor connected in series to the resistance means in the third aspect, wherein the voltage to the high-intensity discharge lamp is At the start of power supply or when the power is turned on, the power reference value is once suddenly increased 50% to 150% higher than the steady value, and the increase is reduced by a predetermined charging time constant and reset by a predetermined discharging time constant. There is provided a lighting device for a high-intensity discharge lamp comprising a fourth power reference value correcting means .
[0007]
[Action]
Examining the characteristics of the tube of a high-intensity discharge lamp, the lamp voltage immediately after lighting an xenon-enclosed automotive lamp is several tens of volts. To do. Thereafter, the mercury in the lamp is vaporized, and the lamp voltage increases as the pressure inside the tube increases. At this time, the luminance rises with a delay with respect to the rise of the lamp voltage. It is possible to start up at high speed by applying power control corresponding to the lamp characteristics. That is, control corresponding to the lamp terminal voltage and control corresponding to the time delay are performed. Specifically, the time until xenon is activated (depending on the current that flows in an automobile lamp, but 0.5 seconds or less as an example), the lamp voltage is relatively high. When the voltage drops and the current increases excessively, the current is limited to about 5 to 7 times the steady value. Since the luminance increases with time, the power supplied to the lamp is reduced. If the time constant for reducing this power is changed from 10 seconds to 30 seconds, the steady power will be reached in about 1 minute, and the brightness will reach within ± 10% of the steady value within a few seconds after lighting. Keep a constant value.
[0008]
On the other hand, the high-intensity discharge lamp is often turned on immediately after being turned off. In this case, if the power control as described above is performed, there is a problem in that the surroundings are adversely affected, such as being too bright and too dazzling, or shortening the lamp life. In addition, when the lamp is turned on immediately after the lamp is turned off, if the current is set according to the lamp voltage without correcting the power, the current becomes too small. For example, if the lamp power is 35 W and the voltage is 80 V, the lamp current is about 0.44 A and the arc Discharging cannot be maintained, causing a problem of disappearance. In addition, the lamp internal pressure decreases as the lamp turns off, 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 returns to the initial value. Note that it takes several hours at room temperature in the dark to be exactly the same.
[0009]
Therefore, it is necessary to supply a lamp current that can reliably maintain the arc discharge when relighting after the light is turned off, and to change the power at the time of relighting according to the time that the light has been turned off.
[0010]
For this control, when re-lighting, power is supplied from 1.5 to 2 times the steady power, and the time constant is reduced from 0.5 to 2 seconds. The time constant circuit for relighting needs to be operated even when the lamp turn-off time is extremely short, such as about 1 second, and is reset immediately after the turn-off is detected.
[0011]
Further, as described above, the lamp voltage due to re-lighting returns to a steady value after several tens of seconds after the light is turned off, so that the discharge time constant for resetting the fourth power correction means is changed from 10 seconds to 30 seconds, so that 30 seconds to 1 seconds. The reset is completed in about minutes, and the same rise as normal lighting. In addition, by using a time constant circuit, it is possible to supply power almost suitable for relighting during reset.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
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 source 1 is connected to both ends of a primary winding of a transformer 3 and a main current terminal of an FET 2 which is a switching element. The FET 2 is on / off driven and controlled at a high frequency by a control circuit 5 connected to its gate. The control circuit 5 is supplied with power by the control circuit power supply circuit 4. The current is rectified by the rectifier circuit 6 connected to the secondary winding of the transformer, and further converted into a rectangular wave by the switching circuit 7. This rectangular wave is supplied to the high-intensity discharge lamp 9 through the igniter 8. The igniter 8 gives a trigger waveform when the high-intensity discharge lamp 9 is started.
[0013]
For each terminal of the control circuit 5, the terminal A is connected to the gate of the FET 2, the terminal B is connected to one end of the rectifier circuit 6 that is proportional to the voltage of the high-intensity discharge lamp 9, and the terminal C is connected to the high-intensity discharge. It is connected to one end of a resistor 11 which is a point proportional to the current of the 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 control circuit power supply circuit 4. The terminal F is connected to an operation signal when the high-intensity discharge lamp 9 is lit.
[0014]
FIG. 2 is a diagram showing details of the control circuit 5 in this embodiment. Terminals A, B, C, D, and E in FIG. 2 correspond to terminals having the same reference numerals in FIG. The control circuit 5 is roughly divided into a first power reference value correcting means 510, a second power reference value correcting means 520, a third power reference value correcting means 530, and a fourth power reference value. It comprises a value correction means 540, a multiplier 550, an activation signal control circuit 560, an error amplification circuit 570, a current limiting circuit 580, and a pulse width modulation circuit 590.
[0015]
The multiplier 550 performs a function of calculating an instantaneous power signal of the high intensity discharge lamp 9. 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 negative input terminal of operational amplifier 571. For the multiplier 550, it is convenient to use a widely used integrated circuit, but a multiplier circuit can be configured by combining a plurality of operational amplifiers.
[0016]
The error amplifying circuit 570 includes an operational amplifier 571 and resistors 571, 572, 573, 574, 575 and the like. In this error amplifying circuit 570, the instantaneous power signal from the multiplier 550 is divided to an appropriate value by the resistor 574 and the resistor 573 and sent to the negative input terminal of the operational amplifier 571. Further, the voltage from the terminal E is divided by the resistors 576 and 572 and supplied to the + input terminal of the operational amplifier 571. A feedback resistor 575 is connected between the output terminal and the negative input terminal of the operational amplifier 571.
[0017]
The pulse width modulation circuit 590 receives the output signal of the operational amplifier 571 and sends a necessary pulse width modulation output signal to the 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 is connected to the reference power source 582. When the reference value is exceeded, the pulse width modulation circuit 590 is output. Operates to limit or stop the output of the.
[0018]
In the configuration described so far, an instantaneous power value that is a product of the instantaneous voltage of the high-intensity discharge lamp 9 and the detected value of the instantaneous current, and a power reference value that is the voltage across the resistor 572 are obtained by the error amplification circuit 570. In comparison, the pulse width modulation circuit 590 operates so that they are equal.
[0019]
In the above description of the configuration, the power reference value correcting means has been excluded, but the following description includes the power reference value correcting means.
[0020]
The first power reference value correcting means 510 includes an operational amplifier 511, a reference voltage 514 connected between the + input terminal and the common line, and a feedback resistor connected between the − input terminal and the output terminal. And a resistor 515 and a diode 516 connected in series to the output terminal. The first power reference value correcting means 510 starts operating when the terminal voltage of the high-intensity discharge lamp 9 falls below the normal operating range including variations, and the power reference value increases as the voltage of the high-intensity discharge lamp 9 decreases. It will increase the 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.
[0021]
Next, the activation signal control circuit 560 will be described. The start signal control circuit 560 converts the lighting operation signal appearing at the terminal F when the high-intensity discharge lamp 9 is lit into the second power reference value correction unit 520, the third power reference value correction unit 530, and the like. This circuit is commonly provided to the fourth power reference value correcting means 540. As for the configuration, a gate logic circuit 561, a resistor 562, a resistor 563, a resistor 564, and a diode connected to the input terminal thereof are individually connected in series to the output terminal via a diode 568 for preventing a backflow. 565 and resistor 567.
[0022]
The second power reference value correction means 520 receives an operation command from the lighting device 10 and changes the level of the operation start signal at the terminal F from L to H and the output level of the gate logic circuit 561 from H to L. The pnp-type 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 time constant circuit is reset via the diode 524. Accordingly, the discharge time constant is almost the same as the charge time constant, but the residual charge of the control circuit power supply 4 remains at the terminal E for a short time after the power supply is cut off and the discharge lamp 9 is turned off. 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.
[0023]
The third power reference value correcting means 530 outputs an operation command to the lighting device 10, the level of the operation start signal at the terminal F changes from L → H, and the output level of the gate logic circuit 561 changes from H → L. The transistor 531 is turned on to increase the reference voltage, and the increase in the reference value is reduced by the time constant of the capacitor 532 and the resistor 533. The time constant circuit is reset through the diode 564, the diode 534, and the resistor 565 at the same time as the level of the operation start signal of the lighting device 10 changes from H to L and the operation of the lighting device 10 is stopped.
[0024]
The fourth power reference value correcting means 540 receives an operation command from the lighting device 10 and changes the level of the operation start signal at the terminal F from L to H and the output level of the gate logic circuit 561 from H to L. The transistor 541 is turned on to increase the reference voltage, and the increase in the reference value is reduced by the time constant of the capacitor 542 and the resistor 543. The time constant circuit is reset through 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.
[0025]
FIG. 3 shows an example of the characteristics of the first power reference value correcting means 510. 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 correcting means 510 for the first power reference value. 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 when the ratio of the applied voltage becomes 20% or more, it falls linearly and about 70% of the applied voltage. In the above, the correction value becomes an asymptotic line of zero. However, these correction value curves act as an addition value to 100% of the original power reference value.
[0026]
For the above correction values, the following constants are set as a preferred embodiment.
[0027]
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.
[0028]
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.
[0029]
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.
[0030]
The time constant of the reset circuit constant (related to the capacitor 542 and the resistor 544) of the fourth correction means is set to approximately 30 seconds to 120 seconds.
[0031]
Also, as the operation setting, the total correction value of the first to fourth correction means is 200% or more, the power supplied to the high-intensity discharge lamp at the time of starting is about three times that of the steady state, the rise is accelerated, and the supply The current limiting means suppresses the current from significantly increasing during an accident such as a voltage drop or an output short-circuit by about 5 to 7 times that in the steady state, thereby preventing the life of the high-intensity discharge lamp and the size of the ballast from becoming large.
[0032]
FIG. 4 shows an example of the characteristics of the correction means for the second, third, and fourth power reference values. The horizontal axis represents the elapsed time after the voltage is applied to the high-intensity discharge lamp, and the vertical axis represents the percentage value of the correction means for the second, third, and fourth power reference values. The second correction value (2) is the highest value + 40%, the third correction value (3) is the highest value + 30%, the fourth correction value (4) is the highest value + 70%, and the sum of these ( 2) The correction value of + (3) + (4) is + 140%. In either case, the maximum values are shown immediately after the start of the operation, and then slowly descends and approaches the asymptotic zero.
[0033]
The total added value of the correction value of the first power reference value shown in FIG. 3, the correction values of the second, third, and fourth power reference values shown in FIG. 4 and 100% of the original power reference value is , And supplied to the + input terminal of the operational amplifier 571, the power having a value that is always equal to the power reference value of the total addition is supplied to the high-intensity discharge lamp 9.
[0034]
FIG. 5 shows the starting characteristics when the high-intensity discharge lamp is cold. Immediately after this startup, the power reference value exceeds 300%, and after that, it gradually falls in about 5 seconds, and after a few tens of seconds, reaches the rated value of 100%. A current flows through the high-intensity discharge lamp corresponding to the characteristics of the power reference value. The light output reaches almost 100% in 3 to 5 seconds.
[0035]
FIG. 6 shows the operation when the high-intensity discharge lamp being turned on is once turned off and then turned on again. When the light is turned on again after 1 second, the maximum current value is suppressed to 130%. When it is turned on again after 5 seconds, the maximum current value is suppressed to 150%, and after 10 seconds, it is suppressed to 180%.
[0036]
FIG. 7 is a diagram showing another embodiment of the control circuit 5. A transistor is not used for the second correction means, only a resistor and a capacitor are used, and everything else is the same. The operation start timing of the second power reference value correcting means is not received from the activation signal control circuit 560, but is simply operated when the power is turned on, thereby simplifying the configuration and making it economical. Similarly, the simplified configuration can be used for the third and fourth power reference value correction means.
[0037]
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 is similar in configuration to the circuit shown in FIG. 2 in that the charging characteristic of the capacitor 532 is used, but a time constant circuit including a resistor 535, a capacitor 532, and a resistor 533 is provided on the base side of the transistor 531. The third power reference value correcting means 530 is configured by arranging and amplifying the charge characteristic of the time constant circuit by a transistor 531. This circuit utilizes the current amplification effect of the transistor, and therefore, even when the time constant is increased, even if the resistance value is increased, the output impedance can be kept low, and more stable operation can be achieved. There are advantages. Similarly, the second power reference value correcting means 520 and the fourth power reference value correcting means 540 can also use this configuration.
[0038]
In the embodiment of the present invention, with respect to the configuration using the multiplier 550, an adding means can be used in place of the multiplying means in practice. In other words, since the combination of the current value and the voltage value, which is the operating point at which the correction of the power reference value acts, is near one point, a coefficient is set for the combination of current and voltage corresponding to this operating point. Thus, the same operation result can be obtained. When expressed in mathematical formulas, if a and b are coefficients, x is a voltage value, and y is a current value, the following equation is satisfied.
[0039]
ax + by = ax · by
[0040]
That is, it is possible to set the coefficients a and b such that this equation holds, and in this state, the operation of the present invention can be approximately realized.
[0041]
The high-intensity discharge lamp lighting device according to the present invention can be started up at high speed by performing similar control not only for automobiles but also in high-intensity discharge lamp lighting devices used, for example, for OHP and projector TVs. Become. In this case, if the speed as high as that for automobiles is not required, the power may be changed to about twice.
[0042]
【The invention's effect】
Since the present invention has the characteristics as described above, when the high-intensity discharge lamp is turned on, the brightness of the high-intensity discharge lamp can be raised to 90% or more of the steady state in 3 to 5 seconds after the power is turned on. it can. Because it is controlled based on the instantaneous current and voltage of the tube, changes in tube type and fluctuations in the power supply voltage will not affect the lighting characteristics, and the expected lighting characteristics will always be maintained. Obtainable. Moreover, 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 a lighting device for a high-intensity discharge lamp according to the present invention.
FIG. 3 shows the characteristics of the first power reference value correcting means.
FIG. 4 shows characteristics of correction means for second, third, and fourth power reference values.
FIG. 5 shows the starting characteristics when the high-intensity discharge lamp is cold.
FIG. 6 shows an operation when a high-intensity discharge lamp that is on is 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]
DESCRIPTION OF SYMBOLS 1 ... Main power supply 2 ... FET 3 ... Transformer 4 ... Control circuit power supply circuit 5 ... Control circuit 6 ... Rectification 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)

Means for measuring the instantaneous current of the high-intensity discharge lamp, means for measuring the instantaneous voltage, multiplication means for calculating an instantaneous power value by multiplying the output signals of these instantaneous current measuring means and the instantaneous voltage measuring means, An operational amplifier that receives the instantaneous power value at one input terminal and a power reference value at the other input terminal and calculates them, and pulse width modulation that outputs an output signal from the operational amplifier as a pulse width modulation signal In a lighting device for a high-intensity discharge lamp, comprising a control circuit comprising a circuit and controlling power supplied to the high-intensity discharge lamp by controlling a switching element by the control circuit ,
The control circuit includes:
Resistor means connected to the other input terminal of the operational amplifier to produce the power reference value;
Correction means connected in series to the resistance means, the first power reference value correction means for increasing the power reference value appearing in the resistance means according to the voltage of the high-intensity discharge lamp,
A correction means having a first time constant circuit comprising a series-connected capacitor and a resistor in the resistance means, said first time constant circuit when the voltage supply start or power supply to the high-intensity discharge lamp A second power reference value correcting means for once sharply increasing the power reference value by a current flowing through the current and reducing the increase by a predetermined time constant ;
High-intensity discharge lamp lighting device, characterized in that it comprises a. In claim 1,
A lighting device for a high-intensity discharge lamp, wherein the second power reference value correcting unit temporarily increases the power reference value sharply by 30% to 80% higher than a steady value . In claim 2,
Compensation means having a second time constant circuit comprising a capacitor and a resistor connected in series to the resistance means, wherein the power reference value is set to the steady state when voltage supply to the high-intensity discharge lamp is started or when power is turned on. A third power reference value that is immediately reset when the power supply to the high-intensity discharge lamp is stopped, while increasing the value sharply once by 30% to 80% higher than the value, and decreasing the increase by a predetermined time constant. A lighting device for a high-intensity discharge lamp, comprising a correcting means . In claim 3,
Compensating means having a third time constant circuit comprising a capacitor and a resistor connected in series to the resistance means, wherein the power reference value is set to the steady state when voltage supply to the high-intensity discharge lamp is started or when power is turned on. And a fourth power reference value correction means for once increasing steeply from 50% to 150% higher than the value, decreasing the increased amount with a predetermined charging time constant, and resetting with a predetermined discharging time constant. A lighting device for a high-intensity discharge lamp.

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