JP4059053B2 - Lighting method of high pressure discharge lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lighting method for a data projector or the like having a high-pressure AC discharge lamp that applies a high-pressure pulse at the time of starting, such as a high-pressure mercury lamp or a metahalide lamp.
[0002]
[Prior art]
As a lighting method having a conventional high-pressure AC discharge lamp, the one described in Patent Document 1 is known.
[0003]
FIG. 13 is an AC current waveform diagram of AC lamp current of a lighting device having a conventional high-pressure AC discharge lamp.
[0004]
Conventionally, the discharge arc became unstable during the lighting of the high-pressure AC discharge lamp, and flicker occurred in the AC discharge lamp. This is due to the movement of the starting point of the discharge arc. The reason is that when operating with alternating current, the anode starting point is compared in the discharge in high-pressure steam due to the difference in operating mechanism between the anode and cathode of the high-pressure AC discharge lamp. This is because the cathode starting point is very small but the cathode starting point is not constant where it can be made. To make it constant, the temperature of the anode starting point is raised in a spot manner to stabilize the cathode starting point in the anode starting point. It will be necessary.
[0005]
Conventionally, when a high pressure discharge lamp is operated with an AC lamp current as a countermeasure against this flicker, a current pulse is generated at a predetermined half of the AC lamp current half-synchronously as shown in FIG. The polarity of the electrode of the high-pressure discharge lamp is made just before the polarity inversion due to the alternating current waveform in which the polarity is made the same as the polarity of the alternating lamp current and the current pulse is superimposed on the alternating lamp current in the part after the half cycle in which the current pulse is generated. Therefore, the discharge arc is generated from the same location, and the stability of the discharge arc is increased to suppress the flicker of the high pressure discharge lamp.
[0006]
[Patent Document 1]
JP 10-501919A [0007]
[Problems to be solved by the invention]
This conventional lighting method has the problem that the brightness of the lamp tends to change due to the steep rise of the current pulse superimposed on the AC lamp current, and it is difficult to control the lamp power at a constant level. It was.
[0008]
The present invention solves the above-mentioned conventional problems, and uses a lighting method that suppresses flicker during lighting of a high-pressure discharge lamp, stabilizes the brightness of the lamp with a simple circuit configuration, and stabilizes control. The purpose of the electronic equipment is to provide a longer lamp life.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
[0010]
According to the first aspect of the present invention, in particular, when a high pressure discharge lamp is lit with an AC lamp current, the AC current waveform of the AC lamp current increases from the commutation of the rectangular wave to the average current. And a second step that becomes flat when the average current is reached, and a third step that increases until commutation, and then the average current constant waveform. The lamp power decrease amount by the first step with respect to the power is made equal to the lamp power increase amount by the third step with respect to the average lamp power.
[0011]
The lighting method of the high pressure discharge lamp according to the present invention, the alternating-current waveforms of the alternating lamp current, and increases after the commutation of the rectangular wave to the average current in a plurality of staircase becomes a flat If the average current is reached, then a plurality of Since the staircase wave is increased before commutation, the electrode temperature of the discharge lamp is increased before commutation. As a result, the discharge arc is generated from the same location, the stability of the discharge arc is increased, and the flicker of the discharge lamp is suppressed.
[0012]
Furthermore, after commutation, by increasing from a current lower than the average current to the average current, the current before commutation can be averaged to obtain an average current flowing in the discharge lamp, and the lamp flicker can be reduced while reducing the lamp flicker. It becomes possible to reduce the luminance change. By reducing the power waveform equivalent to the increase in lamp power, the change in lamp brightness can be minimized, and at the same time, the change in lamp power can be suppressed and the life of the lamp can be extended.
[0013]
In the invention according to claim 2 of the present invention, in particular, the first step increases the average current with a plurality of step waves after the commutation of the rectangular wave, and the third step before the commutation with the plurality of step waves. Is to increase.
[0014]
In the lighting method of the high pressure discharge lamp according to the present invention, it is easy to stably and constantly control the lamp power by increasing the AC lamp current waveform stepwise. Further, it is possible to easily program the microcomputer, and it is possible to reduce the change in luminance of the discharge lamp while reducing the lamp flicker.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a configuration of a high pressure discharge lamp lighting device according to the present invention. The high pressure discharge lamp lighting device of FIG. 1 is connected to the high pressure discharge lamp (lamp) 11 from the DC power source 1 through a DC-DC converter 50 and an AC conversion circuit 51. The DC-DC converter 50 converts the voltage of the DC power source 1 into a high frequency voltage of several tens KHz by a PWM control signal 58 from the control circuit 54, and obtains a lamp output voltage by smoothing. The control circuit 54 controls the output current supplied to the high pressure discharge lamp 11 to be variable.
[0016]
Here, the igniter 6 for lighting the high-pressure discharge lamp 11 by first applying a high voltage (about 20 KV) is connected to the high-pressure discharge lamp 11 via the AC conversion circuit 51.
[0017]
The AC conversion circuit is composed of four switching elements, and each switching element is switched and controlled by a drive circuit 52 to supply AC power to the high-pressure discharge lamp. From the lighting waveform generation circuit 53, a rectangular wave signal 24 of several tens to several hundreds Hz is output and processed into an AC conversion drive signal by the drive circuit 52. Further, the lighting waveform generation circuit 53 outputs a staircase signal 57 for reducing lamp flicker. The control circuit 54 detects the lamp output voltage 55 and the lamp output current with the resistor 23, and detects the lamp output current. A PWM control signal 58 is obtained by combining with the signal obtained by multiplying the voltage 56. With the above configuration, the power of the high-pressure discharge lamp 11 can be controlled to be constant and the brightness can be kept constant.
[0018]
(Embodiment 1)
The first embodiment will be described below. FIG. 2 is an AC drive waveform diagram of the high-pressure discharge lamp 11 according to Embodiment 1 of the present invention. 2, (a) is an AC lamp voltage waveform applied to the high-pressure discharge lamp 11, (b) is an AC lamp current waveform flowing through the high-pressure discharge lamp 11, and (c) is consumed by the high-pressure discharge lamp 11. The lamp power waveform is shown. FIG. 2D shows a part of the lamp power waveform consumed by the high-pressure discharge lamp 11 shown in FIG.
[0019]
The AC lamp voltage waveform applied to the high-pressure discharge lamp 11 of FIG. 2A is a rectangular wave because the voltage (VLa) is substantially constant due to the discharge characteristics of the lamp, and the rectangular wave frequency is several tens to several tens. Set to a value that will increase the lamp life within 100 Hz.
[0020]
FIG. 2B shows an AC lamp current waveform flowing through the high-pressure discharge lamp 11, which increases from t3 after commutation of the rectangular wave to t4 with a plurality of staircase waves, becomes flat when reaching a predetermined current, and then from t5 In order to obtain a current waveform that increases to t6 before commutation by a staircase waveform, a waveform similar to the above waveform is output from the signal line 57 from the lighting waveform generation circuit 53 of FIG. To control the DC-DC converter 50.
[0021]
By the above control, the current flowing through the high-pressure discharge lamp 11 increases from time t5 to time t6 in FIG. 2B, so that the electrode temperature rises to the highest value immediately before polarity inversion. Due to this temperature rise, the discharge arc is generated from the same location, so the stability of the discharge arc is increased and the flicker of the discharge lamp is suppressed.
[0022]
Here, since the lamp power waveform in FIG. 2C increases from time t5 to time t6, the brightness of the lamp also increases. Therefore, as shown in FIG. 2D, the waveform surrounded by the ellipse in FIG. 2C is extracted, and the power waveform (power) from time t6 to t7 equivalent to the lamp power increase (power area A) from time t5 to t6. By reducing the area B) equally, the lamp power becomes a predetermined power between t4 and t5 when the time t5 to t7 is averaged, and the change in the brightness of the lamp can be minimized. Further, by gradually increasing the AC lamp current waveform from time t5 to time t6, it becomes easy to stably and constantly control the lamp power.
[0023]
Here, if the predetermined current between t4 and t5 in FIG. 2B is set to the average current, the lamp power increase (power area A) from time t5 to t6 in FIG. 2C and the power from time t6 to t7. The waveform (power area B) is a point-symmetric waveform, and the power area can be made equal to obtain an average power. As a result, a plurality of staircase currents after rolling can have the same waveform (time of one staircase and current amplitude), and the microcomputer can be easily programmed.
[0024]
Further, the AC lamp current does not change abruptly, and at the same time, the increase in lamp power is reduced to the same extent immediately thereafter, so that the change in lamp power can be suppressed and the lamp life can be extended.
[0025]
However, the increase in lamp power from time t5 to t6 (power area A) and the power waveform from time t6 to t7 (power area B) can be made equal, and the point P2 in FIG. As shown in FIG. 2 (d), by reducing the power waveform (power area D) in the same amount of time as the lamp power increase (power area C), the lamp power averages to a predetermined power, and the brightness change of the lamp also changes. It is possible to keep it to the minimum.
[0026]
Even if the time interval and the waveform are different, the effect of extending the lamp life is the same.
[0027]
(Embodiment 2)
The second embodiment will be described below. FIG. 3 is a detailed circuit configuration diagram of the block diagram showing the configuration of the high pressure discharge lamp lighting device according to the present invention shown in FIG. The lighting waveform generation circuit 53 shown in FIG. 3 includes the microcomputer 18 and the D / A converter 17 and outputs a rectangular wave signal 24 of several hundred Hz and a staircase signal 57 for reducing lamp flicker. The control circuit 54 generates a signal proportional to the lamp power, and the lamp flicker generated by the lighting waveform generation circuit 53 by the division circuit 15 is obtained by multiplying the lamp output voltage 55 by the lamp output current detection voltage 56. Dividing by the reduced staircase signal 57, the DC-DC converter 50 is controlled by the PWM control signal 58 from the comparison circuit 13 through the low-pass filter circuit 14, and an AC lamp current waveform flowing through the high-pressure discharge lamp 11 is generated.
[0028]
Here, FIG. 4 is an AC drive waveform diagram of the high-pressure discharge lamp 11 having the above-described configuration. 4, (a) is an AC lamp voltage waveform applied to the high-pressure discharge lamp 11, (b) is an AC lamp current waveform flowing through the high-pressure discharge lamp 11, and (c) is consumed by the high-pressure discharge lamp 11. The lamp power waveform is shown.
[0029]
The AC lamp voltage waveform applied to the high-pressure discharge lamp 11 of FIG. 4A is a rectangular wave because the voltage (VLa) is substantially constant due to the discharge characteristics of the lamp, and the rectangular wave frequency is several tens to several tens. Set to a value that will increase the lamp life within 100 Hz.
[0030]
FIG. 4B shows an AC lamp current waveform flowing through the high-pressure discharge lamp 11, which increases from t3 after commutation of the rectangular wave to t4 with a plurality of arc-shaped staircase waves, becomes flat when reaching a predetermined current, and thereafter t5 A current waveform that increases to t6 before commutation with a plurality of arc-shaped staircase waves is obtained by passing the low-pass filter in the control circuit 54 and controlling the DC-DC converter 50 as the control signal 58.
[0031]
With the above control, the current flowing through the high-pressure discharge lamp 11 increases in a smooth circular arc shape from time t5 to time t6 in FIG. And just before the polarity reversal, the temperature of the electrode rises to the highest value. Due to this temperature rise, the discharge arc is generated from the same location, so the stability of the discharge arc is increased and the flicker of the discharge lamp is suppressed.
[0032]
The smooth arc-shaped staircase waveform can remove harmonic components from the lamp current, facilitating stable and constant control of lamp power, reducing lamp flicker, and smoothing the lamp. Can be lit.
[0033]
(Embodiment 3)
Hereinafter, the third embodiment will be described. FIG. 5 shows an AC drive waveform diagram of the high-pressure discharge lamp 11 according to Embodiment 3 of the present invention.
[0034]
In FIG. 5, (a) is an AC lamp voltage waveform applied to the high-pressure discharge lamp 11, and (b) is an AC lamp current waveform flowing through the high-pressure discharge lamp 11, showing a case where the lamp output is large and a case where the lamp output is small. . (C) shows the lamp power waveform consumed by the high-pressure discharge lamp 11.
[0035]
The AC lamp voltage waveform applied to the high-pressure discharge lamp 11 in FIG. 5A is almost constant because the voltage (VLa) is almost constant due to the discharge characteristics of the lamp, and the AC voltage does not change even when the lamp output is changed. Therefore, the rectangular wave frequency is set to a value that increases the life of the lamp within several tens to several hundreds of Hz.
[0036]
The lamp output is large when the average current of the alternating current flowing through the high-pressure discharge lamp 11 is large (average current 1) in FIG. 5B. When the average current is small (average current 2), the lamp output is small. FIG. 5C shows a lamp power waveform consumed by the high pressure discharge lamp 11. In order to increase the lamp output, it is necessary to increase the average power 1 as well.
[0037]
Here, the lamp flicker is more conspicuous as the lamp output is smaller. When the average current of the alternating current flowing through the high-pressure discharge lamp 11 is small (average current 2) in FIG. 5B, from t2 after the commutation of the alternating lamp current waveform. Lamp flicker is reduced by a waveform that increases to an average current of 2 with a three-step staircase, becomes flat when the average current reaches 2, and then increases to t3 before commutation with a three-step staircase.
[0038]
When the output of the lamp is large, the average current of the alternating current flowing through the high pressure discharge lamp 11 is increased (average current 1) in FIG. 5B, and a two-step staircase wave from t2 after commutation of the alternating lamp current waveform is performed. The number of steps of the staircase wave is reduced by the waveform that increases to the average current 1 and becomes flat when the average current 1 is reached, and then increases to t3 before commutation by the two-step staircase wave.
[0039]
When the lamp output is increased, the number of steps in the AC lamp current wave is reduced, so that the electric shock to the lamp can be reduced, the life of the lamp can be extended, and the brightness of the discharge lamp while reducing the lamp flicker. Change can be reduced.
[0040]
Also, an electrical circuit that increases or decreases the number of steps can be easily achieved.
[0041]
(Embodiment 4)
Hereinafter, the fourth embodiment will be described with reference to FIG.
[0042]
In FIG. 3, 1 is a DC power source and 11 is a high-pressure discharge lamp. The high pressure discharge lamp 11 is connected from the DC power source 1 through a DC-DC converter 50 and an AC conversion circuit 51. The DC-DC converter 50 includes a switching element 2, a PWM circuit 12, a diode 3, a choke coil 4, and a smoothing capacitor 5. The switching element 2 is turned on at a high frequency of several tens of KHz by a drive signal from the PWM circuit 12. It is turned off to convert the voltage of the DC power source 1 into a high frequency voltage of several tens of KHz, and is smoothed by the diode 3, the choke coil 4 and the smoothing capacitor 5. The PWM circuit 12 is controlled by a control circuit 54. The control circuit 54 divides the signal obtained by multiplying the lamp output voltage 55 and the lamp output current detection voltage 56 by the lamp flicker reduction step signal 57 generated by the lighting waveform generation circuit 53 by the division circuit 15, and the filter circuit 14. Then, it is configured to output as a PWM control signal 58 from the comparison circuit 13. The PWM control signal 58 is controlled by the PWM circuit 12 so as to vary the output current supplied to the high-pressure discharge lamp 11 by varying the duty ratio of the switching element 2. The AC conversion circuit 51 includes four switching elements 7, 8, 9, and 10 and inverter circuits 19 and 20 in a drive circuit 52. The switching elements 7, 8, and 9, and 10 are connected in series. The high-pressure discharge lamp 11 is connected to the connection points of the switching elements 7 and 8 and the connection points of 9 and 10 via the igniter 6. These switching elements 7, 8, 9, and 10 are driven by driving elements U1, U2, U3, and U4, respectively. The drive elements U2 and U4 and the drive elements U1 and U3 have opposite output polarities, and the switching circuit 7, the switching element 8, and the switching element 9 and the switching element 10 are dead in the timing circuit 21 so as not to conduct at the same time. Time is provided.
[0043]
A rectangular wave signal 24 of several tens to several hundreds Hz is output from the microcomputer 18 in the lighting waveform generation circuit 53 to the timing circuit 21 and processed into an AC conversion drive signal by the drive circuit 52 described above. The discharge lamp 11 is continuously turned on.
[0044]
The operation of the lighting waveform generation circuit 53 of the high-pressure discharge lamp apparatus configured as described above will be described with reference to FIG.
[0045]
The step signal 57 in FIG. 6A is an output waveform of the D / A converter 17 in FIG. The microcomputer 18 sends “data“ 10 (hex: hex data) ”at time t0 to the D / A converter 17 at time t0, data“ 20 (hex) ”at time t1, and time t2. data “30 (hex)”, data “40 (hex)” at time t3, data “40 (hex)” at times t4 to t6, data “50 (hex)” at time t7, and data “60 at time t8 (Hex) ", data" 70 (hex) "at time t9, and data" 10 (hex) "at time t10 (this is the same as time t0 and will be repeated thereafter) are sequentially sent to obtain the staircase signal 57. Simultaneously, “5V” is output as the rectangular wave signal 24 at time t0 and “0V” is output at time t10 and output in synchronization with the staircase signal 57 shown in FIG. This rectangular wave signal 24 forms an AC lamp current waveform that flows through the high-pressure discharge lamp 11.
[0046]
Here, when the times t0, t1, t2,... Are set at the same time interval, the rectangular wave frequency of the AC lamp voltage can be easily set by changing the time setting.
[0047]
With the above signal generating means, the current flowing through the high pressure discharge lamp 11 can be arbitrarily set, and the change in the luminance of the discharge lamp can be reduced while reducing the lamp flicker.
[0048]
(Embodiment 5)
The fifth embodiment will be described below. FIG. 7 is a circuit configuration diagram of the D / A converter 17a and the microcomputer 18 especially of the high pressure discharge lamp according to the fifth embodiment of the present invention.
[0049]
In FIG. 7 in the present embodiment, one ends of resistors 39, 38, and 37 constituting the D / A converter 17a are respectively connected to output terminals P1, P2, and P3 of the microcomputer 18 that can be turned on and off for an arbitrary time. The other end of the resistor is connected in common, the collector of the transistor 33 constituting the constant current source is connected to the short-circuit terminal of the base, the base of the transistor 33 is connected to the base of the transistor 34, and the collector output of the transistor 34 is connected to the resistor output. 36 is connected, the terminal voltage of the resistor 36 is input to the buffer amplifier 35, and the staircase waveform 57 is extracted from the output of the buffer amplifier 35. Resistors 31 and 32 connected to the emitters of the transistors 33 and 34 and the power source 30 suppress variations in the base-emitter voltage Vbe of the transistors 33 and 34.
[0050]
The operation of the lighting circuit configured as described above will be described below with reference to FIG. The terminal voltage of the resistor 36 in FIG. 8A is such that current flows through the resistors 39, 38, and 37 when the output terminals P1, P2, and P3 of the microcomputer 18 are grounded at times t0, t1, t2,. Synthesized by the transistor 33. For example, a current of 5 mA flows only from the resistor 39 from time t0 to t1, and a current of 10 mA flows only from the resistor 38 from time t1 to time t2. From time t2 to t3, the resistors 39 and 38 are supplied simultaneously, so that a current of 15 mA is supplied to the transistor 33. As a result, an equivalent current flows through the resistor 36 (assuming the resistance value is 1 kΩ) by the constant current circuit with the transistors 33 and 34, and the terminal voltage thereof is 0.5V from time t0 to t1, and 1. from t1 to t2. A staircase waveform is sequentially formed like 0V and the terminal voltage of the resistor 36 in FIG. 10A, and a staircase signal 57 is obtained from the output via the buffer amplifier 35. Further, the resistance of the staircase signal 57 can be easily varied by making the resistance 36 variable.
[0051]
With the above signal generating means, the current flowing through the high pressure discharge lamp 11 can be arbitrarily set, and the change in the luminance of the discharge lamp can be reduced while reducing the lamp flicker.
[0052]
(Embodiment 6)
The sixth embodiment will be described below. In the sixth embodiment of the present invention, in the fifth embodiment, the capacitor 40 in the D / A converter 17a circuit of FIG. 7 constitutes an integrating circuit. As a result, the staircase waveform generated at the terminal of the resistor 36 in FIG. 7 is integrated into a circular staircase waveform like the terminal voltage of the resistor 36 in FIG.
[0053]
When the arc-shaped staircase waveform is used in the high pressure discharge lighting device, the AC drive waveform diagram of the high pressure discharge lamp 11 is as shown in FIG.
[0054]
10A shows an AC lamp voltage waveform applied to the high-pressure discharge lamp 11, FIG. 10B shows an AC lamp current waveform flowing through the high-pressure discharge lamp 11, and FIG. 10C is consumed by the high-pressure discharge lamp 11. The lamp power waveform is shown. The waveform (e) is an arc-shaped staircase signal 57 generated at the terminal of the resistor 36 shown in FIG. 9 (a).
[0055]
The staircase signal 57 increases from t0 before commutation to a predetermined current of t1 by a plurality of staircase waves in synchronization with the rectangular wave of the AC lamp current waveform, and becomes flat when reaching the predetermined current, and then a plurality of staircase waves from t2. The waveform increases until t3 before commutation.
[0056]
Then, the control circuit 54 of FIG. 3 multiplies the lamp output voltage 55 and the lamp output current detection voltage 56 by the multiplication circuit 16, and divides the multiplication calculation force by the step signal 57. Further, the DC-DC converter 50 is controlled by the control signal 58 through the filter 14 for stabilizing the control.
[0057]
In the control of the filter 14 and the DC-DC converter 50, an overshoot in which the staircase waveform rises as shown in the alternating current waveform of FIG. The correction is the staircase signal 57 in FIG. 10 (e) obtained by passing the staircase waveform through the low-pass filter. As a result, a smooth staircase waveform angle such as the alternating current waveform in FIG. 5 (b) is obtained. Accordingly, the lamp can be lit more smoothly while reducing the lamp flicker.
[0058]
Further, the AC lamp current does not change abruptly, and at the same time, the increase in lamp power is reduced to the same extent immediately thereafter, so that the change in lamp power can be suppressed and the lamp life can be extended.
[0059]
(Embodiment 7)
Hereinafter, the seventh embodiment will be described. FIG. 11 is an AC drive waveform diagram of the high-pressure discharge lamp 11 according to Embodiment 7 of the present invention. In particular, in FIG. 11B, the AC lamp current waveform flowing in the high-pressure discharge lamp 11 is a waveform that increases from t1 after commutation of a rectangular wave to t2 before commutation by a staircase wave.
[0060]
In particular, if the alternating current waveform of the alternating lamp current is a waveform that increases from after commutation to before commutation with a plurality of staircase waves, the program of the microcomputer can be facilitated. Furthermore, it is possible to reduce lamp flicker with an easy circuit that counts pulses generated at regular intervals without using a microcomputer.
[0061]
Although the embodiment of the present invention has been described above, the microcomputer 18 and the D / A converter 17 of the present invention can easily generate a waveform as shown in FIG. 12 and is optimal for a lamp of a high pressure discharge lamp device. It is possible to provide a simple radio wave waveform.
[0062]
【The invention's effect】
When lighting the high-pressure discharge lamp with an alternating lamp current, AC current waveforms of the alternating lamp current, a first step of increasing after the commutation of the rectangular wave to the average current, and then reaches the average current Tan Taira Lamp current reduction amount by the first step with respect to the average lamp power by the average current, using a constant waveform of the average current consisting of the second step and And the lamp power increase in the third step with respect to the average lamp power , the discharge arc is increased by increasing the temperature of the electrode of the high-pressure discharge lamp to the highest value immediately before polarity reversal. There it with stability generated discharge arc from the same point suppresses the flicker of the discharge lamp increases, we'll reduce the lamp power increment equivalent power waveform More, the luminance change of the lamp also allows to suppress to a minimum, an electronic apparatus using the same are those advantageously possible to provide a long life of the lamp.
[Brief description of the drawings]
FIG. 1 is a block diagram of a high pressure discharge lamp lighting device according to Embodiment 1 of the present invention. FIG. 2 is an AC drive waveform diagram of the high pressure discharge lamp lighting device according to Embodiment 1 of the present invention. FIG. 4 is a specific circuit diagram of the high pressure discharge lamp lighting device according to Embodiments 2 and 4 of the present invention. FIG. 4 is an AC drive waveform diagram of the high pressure discharge lamp lighting device according to Embodiment 2 of the present invention. Fig. 6 is an AC drive waveform diagram of the high pressure discharge lamp lighting device in Fig. 6. Fig. 6 is an operation waveform diagram of the high pressure discharge lamp lighting device in the fourth embodiment of the present invention. FIG. 8 is a circuit configuration diagram of a D / A converter and a microcomputer. FIG. 8 is an operation waveform diagram of the high pressure discharge lamp lighting device according to the fifth embodiment of the present invention. Operating waveform 10 is an AC drive waveform diagram of the high-pressure discharge lamp lighting device according to Embodiment 6 of the present invention. FIG. 11 is an AC drive waveform diagram of the high-pressure discharge lamp lighting device according to Embodiment 7 of the present invention. FIG. 13 is a diagram showing the operation of another high-voltage discharge lamp lighting device.
1 DC power supply 2, 7, 8, 9, 10 Switching element 6 Igniter 11 High-pressure discharge lamp (lamp)
17 D / A converter 18 Microcomputer 24 Rectangular wave signal 27 Sawtooth wave generation signal circuit 50 DC-DC converter 51 AC conversion circuit 52 Drive circuit 53 Lighting waveform generation circuit 54 Control circuit 57 Staircase signal 58 PWM control signal

Claims (2)

When lighting a high-pressure discharge lamp with an AC lamp current, a first step in which the AC current waveform of the AC lamp current increases from the commutation of the rectangular wave to the average current, and then flat when the average current is reached. A decrease in lamp power due to the first step with respect to the average lamp power due to the average current, using a constant average current waveform consisting of a second step and a third step that increases before commutation. A lighting method for a high-pressure discharge lamp in which the amount of increase in lamp power in the third step with respect to the average lamp power is made equal. 2. The high-pressure discharge lamp lighting according to claim 1, wherein the first step increases to an average current with a plurality of step waves after the commutation of the rectangular wave, and the third step increases to before the commutation with a plurality of step waves. Method.

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