JP3189602B2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, discharge lamps having characteristics such as higher luminous efficiency, better color rendering, and longer lifespan than halogen lamps have attracted attention, and are being used as vehicle headlamps. A conventional discharge lamp lighting device is disclosed in the 1983 Annual Meeting of the Illuminating Engineering Society of Japan, Tokyo, Japan. 10 is described.

FIG. 17 is a basic configuration diagram of the above-described conventional discharge lamp lighting device. In FIG. 17, reference numeral 91 denotes a metal halide lamp as a discharge lamp, and reference numeral 92 denotes a lighting circuit for starting and lighting the metal halide lamp 91. The lighting circuit 92 includes a DC power supply 93 and an inverter circuit 9.
4 and a high-voltage pulse generating circuit 95. The DC power supply 93 includes a rectifying / smoothing circuit 97 for rectifying and smoothing the output of a commercial AC power supply 96 and converting the output to a DC. 98, diode 99, choke coil 100, capacitor 101, resistor 102,
3 and 104 and a step-down chopper circuit 106 including a control circuit 105. The step-down chopper circuit 106 detects an output voltage with the resistors 102 and 103, detects an output current with the resistor 104, and The control circuit 105 calculates the two detection signals, and ON / OFF controls the transistor 98 by the output signal of the control circuit 105 so that the output power of the step-down chopper circuit 106 becomes a predetermined value.

The inverter circuit 94 includes a transistor 10
7, 108, 109, and 110 and a drive circuit 111. A period during which the transistors 107 and 110 are turned on by an output signal of the drive circuit 111,
The inverter circuit 94 converts the output of the DC power supply 93 into an alternating current and outputs the alternating current by alternately generating a period during which the 109 is turned on. The high voltage pulse generation circuit 95 generates a high voltage pulse for starting the metal halide lamp 91.

The operation of the discharge lamp lighting device configured as described above will be described below. The metal halide lamp 91 is started by the high voltage pulse generated from the high voltage pulse generation circuit 95. After the start, a signal proportional to the lamp voltage of the metal halide lamp 91 detected by the resistors 102 and 103 and a signal proportional to the lamp current of the metal halide lamp 91 detected by the resistor 104 are calculated by the control circuit 105 and supplied to the metal halide lamp 91. Turn on / off the transistor 98 so that the power becomes the predetermined lamp power.
The FF control is performed and the instantaneous power converted into AC by the inverter circuit 94 does not change with time and a rectangular AC waveform having a constant waveform is always supplied to the metal halide lamp 91, and the metal halide lamp 91 maintains lighting. The AC frequency converted by the inverter circuit 94 is H
Fluctuation of discharge arc due to acoustic resonance phenomenon peculiar to ID lamp, extinguishment, or metal halide lamp 91
Usually, the frequency is set to several hundreds Hz in order to avoid a problem such as rupture of the wire. When the discharge lamp is used for a vehicle headlamp, the AC power supply 96 is a DC battery, and the DC power supply 93 is a boost chopper circuit, but the basic configuration is almost the same.

As a conventional vehicle headlamp, a halogen lamp is used. In the case of a two-lamp type, it has a structure as shown in FIG. In FIG. 18, 121 is a passing beam filament, 122 is a traveling beam filament,
Reference numeral 123 denotes a light-shielding plate provided below the low-beam filament 121, 124 denotes a parabolic reflector that irradiates the light from the low-beam filament 121 and the traveling-beam filament 122 forward, and 125 denotes a parabolic mirror. An outer lens that projects the light reflected at 124 forward.

In the conventional headlamp for a vehicle configured as described above, when a low beam is formed, the low beam filament 121 emits light. At this time, since the low-beam filament 121 is positioned ahead of the focal point of the parabolic reflector 124, light traveling downward from the low-beam filament 121 is reflected by the parabolic mirror 124 and then reflected upward. The light becomes glare light and is shielded by the light shielding plate 123. In addition, as shown in FIG.
The light going upward from is reflected by the parabolic reflector 124,
The light beam is projected by the outer lens 125 to form a predetermined low beam.

On the other hand, when a traveling beam is formed, the traveling beam filament 122 emits light. At this time,
The traveling beam filament 122 is connected to the parabolic reflector 12.
The light emitted from the traveling beam filament is reflected by the parabolic reflector 124, becomes light having a wide spread in the up and down direction, and is projected forward by the outer lens 125. A predetermined traveling beam is formed. That is, two light emitting portions are formed by using two filaments, and the passing beam and the traveling beam are switched by selectively using each of the light emitting portions.

[0009]

However, the above-described conventional discharge lamp lighting device has a problem that only one light distribution pattern can be formed since the discharge lamp has only one light emitting portion. Furthermore, when a discharge lamp is used for a vehicle headlamp, two light emitting parts cannot be made and used selectively as in a conventional vehicle headlamp using a halogen lamp. Only a passing beam or a traveling beam can be configured.
There is also a problem that it is not possible to switch between the passing beam and the traveling beam unless the vehicle is a headlamp.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a discharge lamp lighting device capable of forming at least two light distribution patterns with one discharge lamp having one arc. It is an object of the present invention to provide a discharge lamp lighting device capable of switching between a passing beam and a traveling beam even with a two-lamp type, particularly when a discharge lamp is used as a light source of a vehicle headlamp.

[0011]

SUMMARY OF THE INVENTION The present invention firstly provides a lighting circuit, a discharge lamp connected to an output terminal of the lighting circuit, and a light control for irradiating light emitted from the discharge lamp in a predetermined direction. Means, wherein the lighting circuit has at least one of an output frequency and a voltage or current or power output waveform.
The discharge lamp is lit by the lighting circuit, and the shape of the discharge arc of the discharge lamp can be changed.

Second, in order to selectively form discharge arcs having different shapes, the lighting circuit varies at least one of an output frequency and a voltage or a current or an output waveform of electric power to form at least two discharge arcs. This is a configuration in which an optical pattern can be formed.

Third, in order to form two light distribution patterns, the lighting circuit varies at least one of an output frequency and a voltage or current or power output waveform, and
Are used as passing beams, and the second light distribution pattern is used as a traveling beam to provide a vehicle headlamp.

Fourth, a linear arc and a curved arc are formed, and a linear arc is used for a frequently used beam.

[0015]

According to the present invention, a plurality of types of signals having at least one of an output frequency and an output waveform changed from the lighting circuit are output from the lighting circuit and applied to the discharge lamp. In the discharge lamp, the shape of the discharge arc, that is, the bending of the discharge arc changes depending on the type of the applied signal. When the shape of the discharge arc changes, the positional relationship with the optical system changes, and the light distribution pattern changes. That is, by changing at least one of the output frequency and the output current waveform of the lighting circuit, the shape of the discharge arc can be changed, and a plurality of light distribution patterns can be formed.

Also, if the output signal of the lighting circuit is configured to correspond to two light distribution patterns and is used as a vehicle headlamp, the first light distribution pattern can be used for passing beams,
The traveling beam can be formed by the second light distribution pattern, and the passing beam and the traveling beam can be switched, so that the passing beam and the traveling beam can be realized by one discharge lamp, and for a vehicle using a two-lamp discharge lamp. A headlight can be configured.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. First, the first experimental result will be described. This shows the relationship between the output current waveform of the lighting circuit, the output frequency, and the degree of bending of the discharge arc. FIG.
FIG. 3 is a view showing a shape of a metal halide lamp which is a discharge lamp used in the study. In the metal halide lamp of FIG. 19, reference numeral 131 denotes quartz glass forming a discharge space;
32 and 133 are electrodes. In the figure, assuming that the length L of the discharge space intersecting the discharge arc is the inner diameter of the central portion of the discharge space which is the maximum inner diameter of the discharge space, the length L of the discharge space intersecting the discharge arc is 2.7 mm.

FIG. 2 is a diagram showing the relationship between the output frequency of the lighting circuit when the discharge lamp shown in FIG. 19 is lit and the degree of the bending of the discharge arc of the discharge lamp. The degree of bending of the discharge arc indicates the distance between the line connecting the centers of the electrodes and the center of the discharge arc. Solid line A shows the characteristics of the output frequency of the lighting circuit and the magnitude of the bending of the discharge arc when the output current waveform of the lighting circuit is a triangular wave, and solid line B shows the lighting circuit when the output current waveform of the lighting circuit is a sine wave. The solid line C shows the characteristics of the output frequency of the lighting circuit and the magnitude of the bending of the discharge arc when the output current waveform of the lighting circuit is a rectangular wave.

FIG. 2 shows that even if the output current waveform of the lighting circuit is the same, the magnitude of the bending of the discharge arc is different if the output frequency is different. Further, it can be seen that even if the output frequency of the lighting circuit is the same, the magnitude of the bending of the discharge arc is different if the output current waveform is different. That is, by changing at least one of the output frequency and the output current waveform of the lighting circuit, the magnitude of the bending of the discharge arc, that is, the shape of the discharge arc can be changed. At this time, even if the voltage is changed to change the output current waveform, the shape of the discharge arc can be changed. That is, if the lighting circuit is configured to be able to change at least one of the output frequency and the output current waveform, a plurality of discharge arcs having different shapes can be selectively formed. And a discharge lamp lighting device capable of forming a plurality of light distribution patterns can be realized. Normally, when a discharge lamp is turned on at a high frequency, there are intermittently a frequency range in which a discharge arc fluctuates due to an acoustic resonance phenomenon, extinguishment, and the like, and a frequency range in which the discharge lamp is stably turned on.
For each output current waveform, the discharge lamp was
The magnitude of the discharge arc bending was shown only in the range of 10 to 10 kHz.

Next, a specific embodiment based on the experimental results will be described. FIG. 1 shows a configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention. 1, reference numeral 11 denotes a discharge lamp, and 12 denotes a discharge lamp 11.
It is a lighting circuit for starting and lighting. Lighting circuit 1
A DC power supply 1 includes a commercial AC power supply 13 and a rectifying and smoothing circuit 14 for converting the output of the AC power supply 13 into DC.
5, transistors 16, 17, which are switching elements,
An inverter circuit 19 having a capacitor 18 for inputting the DC output of the DC power supply 15 and converting it to AC; a transistor 16 having a drive frequency changeover switch (not shown);
A drive circuit 20 for alternately controlling ON / OFF of 17, a choke coil 21 which is a reactance element for limiting the lamp current of the discharge lamp 11, and a high-voltage pulse generation circuit 22 for generating a high-voltage pulse for starting the discharge lamp 11. Be composed. The high-voltage pulse generating circuit 22 stops generating high-voltage pulses when the discharge lamp 11 is turned on.

The operation of the discharge lamp lighting apparatus according to this embodiment having the above-described structure will be described below. The alternating current input from the alternating current power supply 13 is converted into direct current by the rectifying and smoothing circuit 14, and is again converted into alternating current by the inverter circuit 19. At this time, the output frequency from the inverter circuit 19 is set such that the drive circuit 20 turns on the transistors 16 and 17 alternately.
It changes according to the frequency at the time of N-OFF. Here,
As a combination having different arc shapes, for example, 5 kHz and 10 kHz indicated by circles in FIG. Discharge lamp 1
Until the start of 1, a high-voltage pulse is applied to the discharge lamp 11 from the high-voltage pulse generating circuit 22. When the discharge lamp 11 starts, an AC output from the inverter circuit 19 is applied to a series circuit of the choke coil 21 and the discharge lamp 11,
The current is limited by the choke coil 21 and the lighting of the discharge lamp 11 is maintained. The lamp current waveform at this time becomes a waveform close to a triangular waveform by the choke coil 21 as shown in FIG. When the output frequency of the inverter circuit 19 is 5 kHz and 10 kHz, the shape of the discharge arc is as shown in FIGS. 4A and 4B, and the shape of the discharge arc differs at each frequency. This difference in the shape of the discharge arc, when including the light control means, causes a change in the positional relationship between the discharge arc as the light emitting unit and the light control means, resulting in a change in the light distribution pattern.

As described above, according to the first embodiment,
By switching the drive frequency of the drive circuit 20 and changing the output frequency of the inverter circuit 19, two different discharge arcs can be selected, so that two light distribution patterns can be realized.

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram showing a discharge lamp lighting device according to a second embodiment of the present invention. In FIG. 5, a discharge lamp 31, a high-voltage pulse generating circuit 32 for starting the discharge lamp 31, a power amplifying circuit 33 for amplifying power with a waveform corresponding to an input and supplying power to the discharge lamp 31, and a power amplifying circuit 34 A changeover switch for switching the input to 33, a triangular wave generating circuit 35 for generating a triangular wave, and a rectangular wave generating circuit 36 for generating a rectangular wave.

The operation of the discharge lamp lighting device according to this embodiment having the above-described configuration will be described below. The discharge lamp 31 is started by the high-voltage pulse generated from the high-voltage pulse generation circuit 32. After starting, the power amplifier circuit 33
Supplies power to the discharge lamp 31 to maintain lighting. The output current waveform of the power amplification circuit 33 depends on the input waveform, and in this embodiment, the triangular wave generation circuit 35 and the rectangular wave generation circuit 36
Is input to the power amplification circuit 33 via the changeover switch 34, so that the output current waveform from the power amplification circuit 33 becomes a triangular wave or a rectangular wave. Here, the output frequencies of the triangular wave generation circuit 35 and the rectangular wave generation circuit 36 are indicated by triangles in FIG.
And The shape of the discharge arc when lit with a triangular wave is
As shown in FIG. 4B, the shape of the discharge arc when lit with a rectangular wave is as shown in FIG. By changing the waveform of the output current from the lighting circuit 37 in this manner, the shape of the discharge arc can be changed. This difference in the shape of the discharge arc, when including the light control means, causes a change in the positional relationship between the discharge arc as the light emitting unit and the light control means, resulting in a change in the light distribution pattern.

As described above, according to the second embodiment, by changing the output current waveform from the lighting circuit 37,
Since the shape of the discharge arc can be changed, and two different discharge arcs can be selected by switching the changeover switch 34, two light distribution patterns can be realized.

Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows a configuration diagram of a discharge lamp lighting device according to a third embodiment of the present invention. In FIG. 6, reference numeral 41 denotes a metal halide lamp as a discharge lamp, and reference numeral 42 denotes a lighting circuit for starting and lighting the metal halide lamp 41. The lighting circuit 42 includes a DC power supply 43, an inverter circuit 44, a high-voltage pulse generating circuit 45, and a choke coil 46 which is a reactance element for limiting a lamp current of the discharge lamp 41.

A DC power supply 43 rectifies and smoothes the output of a commercial AC power supply 47 and converts it to DC. The DC power supply 43 receives the output of the rectification and smoothing circuit 48 and supplies power to the discharge lamp 41 to a predetermined value. It comprises a transistor 49 to be controlled, a diode 50, a choke coil 51, a capacitor 52, resistors 53, 54, 55 and a step-down chopper circuit 57 constituted by a control circuit 56. The step-down chopper circuit 57 includes a resistor 53, The output voltage is detected at 54 and the resistance 5
5, the control circuit 56 calculates two detection signals, and ON / OFF controls the transistor 49 by the output signal of the control circuit 56 so that the output power of the step-down chopper circuit 57 becomes a predetermined value. .

The inverter circuit 44 includes a transistor 5
8, 59, 60, 61, and a drive circuit 62 having a drive frequency changeover switch (not shown). A period during which the transistors 58, 61 are turned on at a predetermined frequency corresponding to the drive frequency changeover switch, and a transistor 5
The inverter circuit 44 converts the output of the DC power supply 43 into AC and outputs it by alternately generating the periods during which the switches 9 and 60 are turned on. The high-voltage pulse generating circuit 45 generates a high-voltage pulse for starting the metal halide lamp 41.

The operation of the discharge lamp lighting device according to this embodiment having the above-described structure will be described below. The metal halide lamp 41 is started by the high voltage pulse generated from the high voltage pulse generation circuit 45. After starting, resistance 5
The control circuit 5 outputs a signal proportional to the lamp voltage of the metal halide lamp 41 detected by 3 and 54 and a signal proportional to the lamp current of the metal halide lamp 41 detected by the resistor 55.
6, the transistor 49 is turned on so that the power supplied to the metal halide lamp 41 becomes a predetermined lamp power.
N-OFF control is performed.

The inverter circuit 44 supplies the metal halide lamp 41 with an AC waveform of a predetermined frequency corresponding to the drive frequency changeover switch of the drive circuit 62, and the metal halide lamp 41 maintains lighting. Here, the output frequency of the inverter circuit 44 is the output frequency at which the discharge arc is stably present and the shape of the discharge arc is different, for example, 400.
The drive circuit 62 is configured so as to be able to switch between Hz and 10 kHz. When the output frequency of the inverter circuit 44 is 400 Hz, since 400 Hz is a relatively low frequency, the current is limited by the DC power supply 43 without being affected by the choke coil 46 as a current limiting element, and the current flowing through the metal halide lamp 41 Has a rectangular wave shape as shown in FIG. When the output frequency of the inverter circuit 44 is 10 kHz, the current flowing through the metal halide lamp 41 by the choke coil 46 as a current limiting element has a triangular waveform as shown in FIG. At this time, as shown in FIG. 4, the shape of the discharge arc when the lamp is lit at each output frequency is different. A change occurs in the positional relationship between the arc and the light control means, resulting in a change in the light distribution pattern.

As described above, according to the third embodiment,
By switching the drive frequency of the drive circuit 62 and changing the output frequency of the inverter circuit 44, the lighting circuit 4
Since two output frequencies and output current waveforms can be varied and two different discharge arc shapes can be selected, two light distribution patterns can be realized.

Next, the results of the second experiment will be described. FIG. 8 shows the relationship between the average sound velocity in the discharge space and the average temperature in the discharge space determined from the amount and amount of the sealed material of the metal halide lamp shown in FIG. 19 and the internal volume of the discharge space. When the temperature at the center of the discharge arc is about 5000 ° C and the temperature near the tube wall is about 1000 ° C, the average temperature in the discharge space is 300
It can be estimated to be 0 ° C., and the sound speed in the discharge space at that time is 414 m / s from FIG. The results obtained by substituting the above conditions into the general formula (Equation 1) to obtain the frequency f are shown in (Table 1).

[0033]

(Equation 1)

[0034]

[Table 1]

Table 2 shows a sine waveform, a triangular waveform, and a conventional 400 Hz rectangular waveform having the frequencies shown in Table 1 when the metal halide lamp A shown in FIG. 19 is lit horizontally. The results of comparing and examining the shape of the discharge arc, the magnitude of the bending of the discharge arc (the distance between the line connecting the electrodes and the center of the discharge arc), the luminous efficiency, the temperature in the upper part of the discharge space, and the temperature in the lower part of the discharge space are shown.

[0036]

[Table 2]

From the above results, while the shape of the discharge arc when lit by the conventional rectangular wave lighting method is clearly curved, the triangular wave waveform having the frequency f obtained from the general formula (Equation 1) is obtained. Is supplied to the lamp, the shape of the discharge arc becomes linear. The reason can be explained by the compression wave generated from the discharge arc. When the compression wave generated from the discharge arc travels toward the tube wall and is reflected in the discharge arc direction on the tube wall, the compression wave generated from the discharge arc in all directions around the discharge arc is reflected and reflected on the tube wall. All compression waves have the same amplitude at the center of the vertical section of the discharge space. Further, it is considered that the amplitude of the compression wave generated from the discharge arc changes almost in synchronization with the change of the instantaneous value of the lamp voltage, the lamp current, or the lamp power. When a waveform in which the instantaneous current or the instantaneous power changes over time is supplied to the metal halide lamp shown in FIG. 19, the amplitude of the compression wave generated from the discharge arc at the center of the vertical section of the discharge space and the reflection on the tube wall cause the discharge arc. The amplitudes of all the compression waves returning to have the same level.

On the other hand, at frequencies other than the general formula (Equation 1),
The amplitude of the compression wave generated from the discharge arc and the amplitude of the compression wave reflected from the tube wall do not become the same level, and the phase of the compression wave generated from the discharge arc and the amplitude of the compression wave generated from the discharge arc and the tube Since the magnitude relation of the amplitude of the compression wave reflected by the wall changes, as a result, the discharge arc moves to the lower amplitude level, so that the discharge arc is not stabilized. That is, at the frequency f represented by the general formula (Equation 1), at the center of the vertical section of the discharge space, the amplitude of the compression wave generated from the discharge arc and the amplitude of all the compression waves reflected on the tube wall are generated from the discharge arc. Irrespective of the phase of the compression wave, the discharge arc is always at the same level in any phase, so that the discharge arc is stabilized at the center of the vertical section.

From the results of the comparative study shown in Table 2, when the discharge arc is curved, the temperature in the upper portion of the discharge space becomes 1000 ° C. or more, but when the shape of the discharge arc becomes linear, the temperature in the upper portion of the discharge space becomes 1000 ° C. or less. You can see that. FIG.
The quartz glass that forms the metal halide lamp shown in
When the temperature exceeds 1000 ° C., the temperature deteriorates rapidly, and devitrification and deformation (bulging) of the quartz glass occur. These cause a reduction in luminous flux and a change in light emission characteristics. By lighting at the frequency f determined by the general formula (Equation 1), the temperature of the upper part of the discharge space where the highest temperature of quartz glass becomes 1000 ° C. or less. As a result, the deterioration of the quartz glass can be suppressed, so that the life of the lamp can be extended. That is, the life of the discharge lamp can be extended by lighting the discharge lamp at the frequency f represented by the general formula (Equation 1) with a waveform in which the instantaneous voltage, instantaneous current, or instantaneous power changes with time.

Although the average temperature during rated lighting is 3000 ° C. here, it can be seen from FIG. 8 that if the average temperature in the discharge space changes, the average sound speed in the discharge space changes. In other words, when the lamp current is varied and dimmed, when the ambient temperature changes, and immediately after the lamp is turned on until the average temperature in the discharge space reaches a predetermined value, the average temperature during rated operation is 3000 ° C. Have different temperatures, so the value of the average sound speed is different for 414 m / s. FIG. 8 is obtained from the filling material of the metal halide lamp shown in FIG. 19, the amount of the filling and the inner volume of the discharge space. It is clear that the average sound speed of the discharge space changes, and the average sound speed in the discharge space has a unique value for each lamp.

Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 9 shows a configuration diagram of a discharge lamp lighting device according to a fourth embodiment of the present invention, in which the discharge lamp lighting device of the present invention is used as a vehicle headlight.

In FIG. 9, reference numeral 72 denotes a discharge lamp; 71, a lighting circuit for starting and lighting the discharge lamp 72;
Reference numeral 3 denotes a parabolic reflector for irradiating light emitted from the discharge lamp 72 forward, and reference numeral 74 denotes an outer lens for controlling light distribution.
As shown in FIG. 10, the lighting circuit 71 includes a DC power supply 77 including a battery 75 as a power supply and a booster circuit 76 for boosting the voltage of the battery to a predetermined voltage, and transistors 78 and 79 as switching elements. DC power supply 7
Inverter circuit 8 which receives the DC output of 7 and converts it to AC
1. A drive frequency changeover switch (not shown) is provided, and the transistors 78 and 79 are converted to a frequency of 76.7 kHz obtained by the general formula (Equation 1) and a frequency at which the discharge arc is stabilized at other frequencies, for example, from FIG. ON ・ O at 10kHz
Drive circuit 82 for FF control, choke coil 8 as a reactance element for limiting the lamp current of discharge lamp 72
3. A high-voltage pulse generating circuit 84 for generating a high-voltage pulse for starting the discharge lamp 72. In addition,
The high-voltage pulse generating circuit 84 stops generating the high-voltage pulse when the discharge lamp 72 is turned on. When the output frequency of the lighting circuit 71 is 76.7 kHz and 10 kHz, the shapes of the discharge arcs are as shown in FIGS. 11A and 11B, respectively.

The operation of the discharge lamp lighting device according to this embodiment having the above-described structure will be described below. The lighting circuit 71 is different from the first embodiment in that
Of the present invention includes a step-up circuit instead of a rectifying / smoothing circuit with direct current because the input is a battery;
The driving frequency of the driving circuits of 8, 79 is 76.7 kHz, 1
Except that the frequency is 0 kHz, the configuration is almost the same, and the basic operation is almost the same as that of the first embodiment. First, a case where a frequently used beam is a traveling beam will be described.

FIGS. 12 and 13 are views showing the position where the discharge lamp 72 is arranged and the direction in which light is emitted. In this case, the discharge frequency of the discharge lamp 72 is set to 7
When 6.7 kHz, that is, the shape of the arc is as shown in FIG. 11A, the parabolic reflector 73 is arranged so that the focal point of the mirror 73 is substantially at the center of the discharge arc. Lighting circuit 7
The output frequency of the discharge lamp 72 is set to 76.7 kHz.
Is turned on, the shape of the discharge arc becomes straight as shown in FIG. 11A, so that the position of the discharge arc, which is the light emitting portion, and the focal point 85 of the parabolic reflector 73 substantially coincide with each other. The light reflected by the reflecting mirror becomes substantially parallel to the optical axis as shown in FIG. 16A, and the light is projected by the outer lens 74 in a predetermined direction, and the traveling beam distribution as shown in FIG. Form a light pattern.

The output frequency of the lighting circuit 71 is 10 kHz.
When the discharge lamp 72 is turned on and the discharge arc 72 is turned on, the shape of the discharge arc becomes more curved than that shown in FIG. 11A, as shown in FIG. Since it is located above the focal point 85 of the reflecting mirror 73, FIG.
As shown in FIG. 3, the light reflected by the reflector becomes light directed downward with respect to the optical axis. Then, the light is projected by the outer lens 74 in a predetermined direction to form a light distribution pattern of a low beam as shown in FIG.

Next, a case where a frequently used beam is a passing beam will be described. 14 and 15
FIG. 4 is a diagram showing a position where a discharge lamp 72 is arranged and a direction in which light is emitted. In this case, when the output frequency of the lighting circuit 71 is 10 kHz, that is, when the shape of the arc is the shape shown in FIG.
3 are arranged so that the focal point is substantially at the center of the discharge arc.

The output frequency of the lighting circuit 71 is 76.7 kHz.
When the discharge lamp 72 is turned on and the discharge arc 72 is turned on, the shape of the discharge arc becomes straight as shown in FIG.
As shown in FIG. 15, the light reflected by the reflecting mirror is directed upward with respect to the optical axis, and is inverted and projected by the outer lens 74 as shown in FIG.
A light distribution pattern of a low beam as shown in FIG.

The output frequency of the lighting circuit 71 is 10 kHz.
When the discharge lamp 72 is turned on and the discharge arc 72 is turned on, the shape of the discharge arc becomes more curved than that shown in FIG. 11A, as shown in FIG. The light substantially coincides with the focal point 85 of the reflecting mirror 73, and the light reflected by the reflecting mirror becomes light parallel to the optical axis as shown in FIG. Then, the outer lens 74 performs inverted projection viewing,
A light distribution pattern of a traveling beam as shown in FIG. 16B is formed.

As described above, according to the fourth embodiment,
By changing the lighting frequency between when the passing beam is selected and when the traveling beam is selected, two light distribution patterns can be formed by a headlight using one discharge lamp having one arc,
Since you can switch between the passing beam and the traveling beam,
A vehicle headlight using a discharge lamp in a two-lamp system can be realized. If the beam is set to be a linear discharge arc when the beam is frequently used, it is possible to suppress the devitrification and deformation (bulging) of the discharge lamp, which causes a reduction in luminous flux and emission characteristics. , Longer life.

In the first embodiment, the lighting circuit 1
The output frequency of No. 2 is set to, for example, 5 kHz and 10 kHz. However, any other frequency may be used as long as the discharge arc is stable and has a different shape. Further, the output current waveform is a triangular wave, but may be another waveform (for example, a sine wave). Although two light distribution patterns are realized, the output frequency of the lighting circuit 12 may be three or more, and three or more light distribution patterns may be realized.

In the second embodiment, the lighting circuit 3
7, the output current waveform is, for example, a triangular wave and a rectangular wave.
If the shape of the discharge arc is different, another combination of waveforms may be used. Although two light distribution patterns are realized, the output current waveform of the lighting circuit 37 may be three or more, and three or more light distribution patterns may be realized.

In the third embodiment, the lighting circuit 4
2, the output current and the output current waveform are, for example, 400 Hz,
Although the rectangular wave and the triangular wave of 10 kHz are used, other combinations may be used as long as the discharge arc is stable and has a different shape. Although two light distribution patterns are realized, three or more light distribution patterns may be realized.

In the fourth embodiment, the parabolic reflector and the outer lens are used as the light control means, but other light control means may be used. The output frequency of the lighting circuit 71 is set to, for example, 76.7 kHz and 10 kHz.
If the discharge arc exists stably and the shape of the discharge arc is different, another combination of frequencies may be used.

[0054]

As described above, according to the present invention,
By configuring the lighting circuit so that a plurality of types of output signals can be applied, a plurality of light distribution patterns can be realized.
Further, by using the discharge lamp lighting device of the present invention for a vehicle headlamp, a vehicular headlamp using one discharge lamp having one arc can switch between a passing beam and a traveling beam, Its practical effect is great.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a lamp current waveform, a lighting frequency, and a degree of bending of a discharge arc.

FIG. 3 is a waveform diagram of an output current of the lighting circuit of the embodiment.

FIGS. 4 (a) and (b) are diagrams showing differences in the shape of a discharge arc.

FIG. 5 is a configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a discharge lamp lighting device according to a third embodiment of the present invention.

FIG. 7 is a waveform diagram of an output current of the lighting circuit of the embodiment.

FIG. 8 is a diagram showing a relationship between an average temperature in a discharge space and an average sound speed in the discharge space.

FIG. 9 is a configuration diagram of a vehicle headlamp according to a fourth embodiment of the present invention.

FIG. 10 is a configuration diagram of a lighting circuit of the embodiment.

FIGS. 11A and 11B are diagrams showing a difference in the shape of the discharge arc of the embodiment.

FIG. 12 is a diagram showing a light distribution direction when a traveling beam is formed in the embodiment.

FIG. 13 is a diagram showing a light distribution direction at the time of forming a low beam in the embodiment.

FIG. 14 is a diagram showing a light distribution direction when a traveling beam is formed in the embodiment.

FIG. 15 is a diagram showing a light distribution direction at the time of forming a low beam in the embodiment.

16A and 16B are diagrams showing light distribution patterns of a passing beam and a traveling beam.

FIG. 17 is a configuration diagram of a conventional discharge lamp lighting device.

FIG. 18 is a configuration diagram of a conventional vehicle headlamp.

FIG. 19 is a view showing the shape of a lamp used in the experiment.

[Explanation of symbols]

 11, 31, 41, 72 Discharge lamp 12, 37, 42, 71 Lighting circuit 15, 43, 77 DC power supply 19, 44, 81 Inverter circuit 20, 62, 82 Drive circuit 22, 32, 45, 84 High voltage pulse generation circuit 43 step-down chopper circuit 73 parabolic reflector 74 outer lens 131 quartz glass 132, 133 electrode

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shigeru Horii 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-56-11895 (JP, A) JP-A-5-95 54990 (JP, A) JP-A-5-82271 (JP, A) JP-A-62-90843 (JP, A) JP-A-61-294751 (JP, A) JP-A-7-14684 (JP, A) JP-A-4-312793 (JP, A) JP-B-5-57693 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 41/14-41/298

Claims (5)

(57) [Claims] 1. A lighting circuit, comprising: a discharge lamp connected to an output terminal of the lighting circuit; and light control means for irradiating light emitted from the discharge lamp in a predetermined direction, wherein the lighting circuit has an output frequency. , Output current waveform , output voltage waveform, output voltage
Has a characteristic that can change at least one of the force waveforms ,
The discharge lamp is turned on by the lighting circuit, the shape of the discharge arc of the discharge lamp is made variable , and a plurality of light distribution patterns are formed.
A discharge lamp lighting device characterized in that a discharge lamp lighting device can be formed . 2. A lighting circuit for selectively forming discharge arcs having different shapes, wherein at least one of an output frequency and a voltage or a current or an output waveform of power is varied to form at least two light distribution patterns. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is capable of being operated. 3. A lighting circuit for forming two light distribution patterns, wherein the lighting circuit varies at least one of an output frequency and an output waveform of a voltage or a current or an electric power, and converts the first light distribution pattern into a low beam. 3. The discharge lamp lighting device according to claim 2, wherein the second light distribution pattern is used as a traveling beam to form a vehicle headlamp. 4. The discharge lamp lighting device according to claim 3, wherein the shape of the discharge arc of the discharge lamp is substantially linear when the beam is frequently used. 5. An output waveform of an instantaneous voltage, an instantaneous current, or an instantaneous power of a lighting circuit at the time of a frequently used beam is a waveform that changes with time, and V is a sound speed in a discharge space medium of a discharge lamp, L Is the length of the discharge space intersecting the discharge arc of the discharge lamp, the output frequency f is (nV) /
5. The discharge lamp lighting device according to claim 4, wherein (2L) is represented by (n is a natural number).