JPH027347A - Xenon-metalhalide lamp - Google Patents

Abstract

PURPOSE: To almost momentarily provide light output by containing a relatively high pressure xenon filler, some amount of mercury and metal halide in an inner envelope. CONSTITUTION: An envelope 16 having a pair of electrodes 30, 32 arranged at the specified distance contains xenon having a pressure of about 2-15atm. at room temperature, about 2-15mg of mercury, and about 2-10mg of a filler comprising a mixture selected from metal halides such as sodium iodide and scandium iodide. When an exciting source is acted to the electrode, the xenon filler is momentarily ionized, emits light, and by continuing the action of the exciting source, mercury is evaporated and ionized together with metal halide.

Description

BACKGROUND OF THE INVENTION The present invention relates to a discharge lamp particularly suitable for the front lighting of motor vehicles such as cars, trucks, buses, pans or tractors. More specifically, the discharge lamp of the present invention provides a xenon-based discharge lamp for automobile headlamps with instant lighting ability, relatively long life and relatively high efficiency.
It is a metal halide lamp.

There is an interest among automotive designers in lowering the hood line of passenger cars in order to improve their appearance as well as their aerodynamic performance. As discussed in U.S. patent application Ser.
The size of this headlamp is limited by the dimensions of the light source itself, which is usually constructed from a tungsten filament.

As disclosed in U.S. patent application Ser. This allows car designers to significantly lower the hood line of their cars. In addition, the xenon discharge light source disclosed therein has the same instantaneous start-up ability as a tungsten filament, so
Particularly suitable for automotive use.

Although xenon light sources perform their desired functions, they suffer from the disadvantage that their efficiency is less than that of other discharge type lamps, such as metal halide lamps.

This drawback is due, in part, to the relatively low operating voltage of xenon lamps, which may be useful for automotive applications, on the order of 15 volts. For this reason, a large part of the energy consumed in such a xenon lamp is wasted by the electrodes of this xenon lamp and does not contribute to the light output. Another reason for this low efficiency is that xenon's spectrum contains a relatively large amount of infrared energy, which is useless for automotive purposes and is used in automotive headlamps. It is also harmful to plastic housings.

It would be desirable to provide discharge lamps, such as metal halide lamps, to meet the needs of automotive headlamps. It is also desirable for metal halide lamps to have near-instantaneous light output capabilities, like xenon lamps and tungsten incandescent light sources. Furthermore, in addition to metal halide lamps meeting the needs of the automotive industry, it is hoped that metal halide lamps will find lighting applications in homes, offices, and other commercial and industrial settings.

It is therefore an object of the present invention to provide a metal halide discharge light source for illumination which is particularly suitable to meet the needs of the automotive industry in the sense of substantially instantaneous ignition.

Yet another object of the present invention is to reduce the size of the associated reflector of the headlamp by having a relatively small size hood line, which is desirable for vehicles with an aerodynamically adapted style. It is an object of the present invention to provide a metal halide discharge lamp that takes into account degradation.

SUMMARY OF THE INVENTION The present invention relates to a xenon-metal halide discharge light source that has a variety of lighting applications and is particularly suitable for automotive headlamps.

In one embodiment, a motor vehicle headlamp consists of a reflector, a lens, and an inner envelope.

The reflector has a portion associated with means connectable to an excitation source of the motor vehicle. The reflector also has a predetermined focal length.

The lens of an automobile headlamp is connected to the front of the reflector. The inner envelope of this automotive lamp is placed at a predetermined position inside the reflector so that it is located near the focal length of the reflector. The inner envelope contains a relatively high pressure xenon filling, some mercury, and metal halides.

This inner envelope has a pair of electrodes separated by a predetermined distance from each other. This inner envelope is connected to means associated with said linkage part of the motor vehicle lamp so that an excitation source can be energized to act on the electrodes, and upon energizing the excitation source, the inner envelope is The xenon filling contained within is excited and emits a large amount of light, which subsequently evaporates and ionizes the mercury along with the metal halide components. The ionization of xenon and metal halides creates a high-intensity, high-efficiency light source between the electrodes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view schematically illustrating an automotive headlamp 10 according to one embodiment of the present invention, which includes a reflector 12, a lens 14, and an inner envelope 16.
It consists of

The reflector 12 has a rear part 18 equipped with means such as a connector 20 with prongs 22, 24 that can be connected to an excitation source of the motor vehicle.

The reflector 12 has a predetermined focal length 26 along the axis 28 of the zero vehicle headlamp 1o. This reflecting plate 12 has a parabolic shape, and its focal length is in the range of about 6 to about 35 mm, and about 8 to about 20+ m.
A range of is preferred. The lens 14 fits in the front of the reflector 12. This lens 14 is made of a transparent material selected from the group consisting of glass and plastic. The transparent member preferably has one surface formed of a prismatic member.

The internal envelope, lobe 16, is located at a predetermined position within the reflector and is located near the focal length 26 of the reflector. In the embodiment shown in FIG. 1, the inner envelope 16 is oriented perpendicularly transverse to the axis 28 of the reflector 12, whereas in FIG.
The inner envelope 16 is shown horizontal to and oriented along.

The inner envelope 16 depicted in FIGS. 1 and 2 is double-headed and has a pair of electrodes 30, 32 which are arranged opposite each other at the neck of the inner envelope. They are separated from each other by a predetermined distance ranging from about 2 meters to about 411 meters. This inner envelope 1
6 may be single-headed, with both electrodes placed at one end of the lamp and separated from each other by a given predetermined range.

The pair of electrodes is preferably made of tungsten and 1 to 3
% of thorium in the group consisting of tungsten. In one embodiment for an inner envelope made of quartz, the rod electrodes are each connected to foil members 34, 36 encapsulated in opposing necks of the inner envelope. These foil members 34.36 are connected to relatively thick internal leads 38.40, each of which is connected to a prong 22.24. Preferably General Electric Co.
#180 available from ctrlc Company)
In another example for a type of glass inner envelope, rod-shaped tungsten electrodes can be welded to molybdenum leads that can be encapsulated directly into #180 glass.

Electrode 30.32 is a Davenport
) et al., US Pat. No. 4,574,219, herein incorporated by reference, are preferred.

Thermionic emission occurs in spot mode electrodes coated with cement materials as disclosed in Table 3 of U.S. Pat. form the conditions necessary to bring about.

The inner envelope 16 consists of an elongated body ranging in length from about 15 to about 40 fins, with a neck about 2 to about 5 mm in diameter and a bulbous central part ranging from about 6 to about 15 l in diameter. It has a central part. This inner envelope 16 may preferably have a coating 4.2 on its outer surface, which coating preferably consists of a multilayer infrared reflective film consisting of alternating layers of tantalum oxide and silicon dioxide, or titanium oxide and silicon dioxide. (film) is preferred. This multilayer infrared reflective film reflects infrared energy emitted by the lamp toward the lamp arc so that the arc temperature increases and is maintained without further increases in input from the excitation source. This improves the efficiency of the operating lamp 16 (described below). This infrared reflective coating 42 is also advantageous in that it additionally absorbs the ultraviolet energy of the lamp 16. If this ultraviolet energy is not absorbed in this way, the headlamp 10
may cause deterioration of plastic parts and other parts. This process of absorbing ultraviolet electromagnetic energy and reflecting infrared electromagnetic energy also has the added benefit of increasing the heating rate of lamp 1.6, thereby evaporating and ionizing the mercury and metal halides inside lamp 16. , thereby reducing the start-up time of the xenon-metal halide lamp 16 when it is operated with high pressure xenon.

The filling contained within the xenon-metal halide lamp 16 consists of xenon, mercury, and metal halide. The xenon fill has a fill pressure ranging from about 2 atmospheres to about 15 atmospheres at room temperature. The amount of mercury contained in a xenon-metal halide lamp ranges from about 2111 g to about 1
The amount is in the range of 0 mg.

This amount of mercury is such that, for a bulb of a certain size and a certain distance between the electrodes, the voltage drop across the lamp is convenient and that no excessive convective currents in the lamp result in arc bending. Select so as not to cause any bending. As a result of the presence of both xenon and mercury, the operating pressure ranges from about 3 to about 100 atmospheres. The metal halide is in the mixture in an amount ranging from about 4 mg to about 12 mg. This mixture consists of halides selected from the group listed in Table 1.

Table 1 An example of a preferred selection of components in the amount of "sodium iodide scandium iodide thallium iodide indium iodide tin iodide dysprosium iodide holmium iodide thulium iodide thorium iodide cadmium iodide cesium iodide" It is a mixture of sodium iodide and scandium iodide. The xenon-metal halide lamp 16 of the present invention is particularly suitable for use as a light source for automotive forward lighting.

When an excitation source is first applied to the electrodes of a xenon-metal halide lamp, the xenon filling instantaneously ionizes and emits light, and then when the excitation source continues to act, mercury evaporates and ionizes together with the metal halide. The instantaneous amount of light varies linearly with the pressure of xenon within the inner envelope. The xenon component of the xenon-metal halide lamp envelope acts to provide sufficient instantaneous light for automotive applications, while the mercury and metal halide components act to create a discharge lamp containing only xenon or a tungsten filament for automotive applications. Ensures a long life headlamp with higher efficiency compared to lamps. A xenon-metal halide light source with a relatively short distance between electrodes of 3 mm starts lighting up virtually instantaneously using xenon gas, thus providing a light output suitable for early automobile applications.This xenon-metal halide lamp It warms up sufficiently within 30 seconds, and the ionization of mercury and metal halides ensures highly efficient output.

To operate a xenon-metal halide lamp in cold (room temperature) conditions, a current of 5 amperes at a voltage of 12 volts is supplied to the lamp so that it operates at approximately 60 watts. As the mercury and metal halides in the lamp ionize and evaporate, the voltage across the lamp gradually increases to about 40 volts, so the current is adjusted to about 1 ampere so that the lamp operates at about 40 watts.

When a voltage is applied to a xenon-metal halide lamp in a cold state, most of the mercury in the metal halide lamp condenses (liquefies), just like the metal halide, and the lamp essentially operates as a high-pressure xenon lamp. During such an initial state, a spot of high intensity light is localized in front of one electrode, resulting in a moderate area of brightness. When the xenon-metal halide lamp 16 is sufficiently warmed up, the xenon light emission is gradually increased by the mercury and metal halide light emission. As the voltage across the lamp begins to rise and the current flowing through the lamp begins to fall, the metal halide lamp's electrode losses decrease and the lamp becomes correspondingly more efficient.

In the practice of this invention, a mixture of sodium iodide and scandium iodide in a molar ratio of 19=1 is used together with mercury in the amount necessary to produce a voltage drop of about 30-50 V and a filling pressure of 5 atmospheres of xenon. It worked satisfactorily when used in a xenon-metal halide lamp of dimensions that met the needs of the automobile industry. This lamp can be mounted on a motor vehicle according to one aspect of the invention. It is also advantageous to select other metal halides, which can be provided with useful colors for automotive applications.

The xenon-metal halide lamp of the present invention, using high pressure xenon, provides sufficient light intensity during the first few seconds of lamp operation to meet automotive lighting needs. After this first few seconds, the mercury and metal halide components inside the inner envelope increase the xenon discharge, ensuring highly efficient light output.

The automotive headlamp 10 of the present invention can meet automotive low beam lighting needs when the xenon-metal halide lamp is excited with a voltage of 30V and a current of 1.4A. The same excitation would provide illumination for the high beam (upward beam).

One of the advantages of the high efficiency metal halide lamp according to the invention is that, due to its relatively small arc size, it is possible to reduce the size of the reflector that houses this metal halide lamp to form a headlamp for an automobile. Therefore, it becomes possible to lower the hood line of the automobile described in the "Background of the Invention" section.

Such a reduction can be explained with reference to FIGS. 3(A) and 3(B).

3(A) and 3(B) are related to each other, and the degree of beam divergence produced by a headlamp using a tungsten filament 116 is compared with that of a headlamp having a smaller xenon-metal halide light source 16 of the present invention. FIG. 4 is a diagram showing a comparison with the degree of beam opening generated by a lamp. FIG. 3(A) shows a light source 116 in the form of an arrow whose center is located at the focal point 26 along the axis 28 of the reflector 12; is the axis 28 of the reflector 12 whose center part has the same dimensions as in FIG. 3(A).
2 shows a xenon-metal halide light source 16 in the form of an arrow located at a focal point 26 along the arrow. The incandescent light source 116 is typically on the order of 5 inches long, whereas the xenon-metal halide light source 16 is approximately 31 inches long.

When activated, the incandescent filament 116 produces a plurality of reflected rays that diverge at a rate proportional to the size of the light source 116 and represented by the angle θ9.
open). Similarly, the xenon-metal halide light source 16 emits a plurality of light beams that diverge at a mutual angle θB.

Referring to FIG. 3(A), the angle of divergence of light from filament 116 is shown by light ray 116A originating from the top portion of filament 116 being blocked by reflector 12 and reflected by light ray 116B. ing. The angle between ray 116B passing through focal point 26 and axis 28 is the divergence angle θA of the light from filament 116. Using the values already mentioned for filament 116 (5 mm) and reflector 12 (focal length 25 mm), this angle θA is 1
It becomes 1.3”.

FIG. 3(B) shows the ray 1 described with respect to FIG. 3(A).
Rays 16A and 16B are shown similar to 16 and 116B. The aperture angle θB caused by the light beam emitted by the xenon-metal halide light source 16 is determined by the angle θB between the light source 16 (3 m+s) and the reflector 12 (focal length 25III1) described above.
For the value of 1), it is 6.80. The opening angle θ is approximately 3/5 of the opening angle θA. The overall effect of the light produced by the xenon-metal halide light source 16 of the present invention is that the desired beam pattern emitted by the vehicle headlamp 10 of the present invention and directed toward the road is less divergent;
Therefore, more light goes to areas where roads need to be illuminated, and less light goes to areas where it is not needed. Xenon-metal halide light source 1 of the present invention
6 compared to an incandescent bulb light source 116, this reduction in spread or unwanted light results in reduced veiling or obscuring effects of fog, rain, and snow, thereby providing more useful direct light for automotive applications.

Another advantage afforded by the relatively small size of the xenon-metal halide light source 16 of the present invention is that it reduces the required size of the automotive headlamp reflector, as shown in FIGS. (B) This can be explained with reference to the figure. Figures 4(A) and 4(B) are similar to Figures 3(A) and 3(B), respectively, and like reference numerals are used where applicable. 4th (A
) and FIG. 4(B) differ in that the focal length 26 is half the focal length 26 shown in FIGS. 3(A) and 3(B). Furthermore, the height of the reflector 12 in FIGS. 4(A) and 4(B) is reduced to about 2/3 compared to that in FIGS. 3(A) and 3(B). There is.

Figure 4(A) shows the tungsten incandescent lamp filament 1.
16 generates light rays 116A and 116B, and this light 116B has an aperture angle θ. In the case of the reflectors shown in FIGS. 4(A) and 4(B) whose focal length is 12.5 degrees, the filament 1 is
Using a value of 16 (length 5 mm) would result in a value of approximately 21.8@, which would result in a sufficient amount of stray light in the beam pattern for a car headlamp; Does not meet technology needs. On the contrary, the fourth (
B) The figure shows a xenon-metal halide light source 16 of approximately 311I11 length producing intervening beams 16 and 16B, which beams 16. is about 13゜5
”, resulting in a beam pattern with a limited amount of stray light, more advantageous to meet the needs of automotive technology. Xenon-metal halide light sources of smaller size Due to the effect of −
The metal halide light source allows the size of the reflector to be reduced and improves the light collection efficiency of the reflector to a sufficient degree, thus allowing automobile designers to lower the hood line of the automobile, as discussed in the Background of the Invention section. You will be able to do this. By implementing the invention, the reflector of an automobile headlamp can be made as small as 273 compared to a conventional automobile headlamp using a normal incandescent lamp filament, so that the automobile hood line is accordingly reduced. be able to lower the

The total reduction in size of the reflector and the corresponding reduction in size of the automotive headlamp can be illustrated with reference to FIGS. 5(A) and 5(B). FIG. 5A is a perspective view illustrating a prior art rectangular automotive headlamp that uses an incandescent bulb filament and has similar elements to the automotive headlamp 10 of FIGS. 1 and 2. , corresponding reference numbers are in the hundreds. FIG. 5(B) is a perspective view illustrating one embodiment of the present invention, and FIG.
A rectangular automobile headlamp 10 shown in the figure,
Its dimensions are reduced by about 40% compared to the prior art lamp 100, as already mentioned in the description of the lamp 10.

As can be readily seen by comparing the prior art lamp 100 of FIG. 5(A) and the lamp 10 of the present invention of FIG. 5(B), by implementing the present invention, an automobile designer can Means in the form of a xenon-metal halide lamp 16 is available which allows the hood line to be lowered considerably.

The implementation of the xenon-metal halide lamp according to the invention not only provides instantaneous light to meet the needs of automotive lighting, but also its reduced dimensions lower the hood line of the vehicle, thus making it suitable for automotive designers. - The aerodynamic style that you desire becomes possible.

The xenon-metal halide lamp of the present invention also has a
．． Relatively long lifetimes of 0,000 hours are also expected, thus meeting the need for longer expected lifetimes for automotive headlamps.

Furthermore, an infrared multilayer film coating on the outside of the inner envelope of a xenon-metal halide lamp increases the efficiency of the lamp by reflecting infrared radiation toward the arc of the xenon-metal halide lamp; It will be appreciated that this reduces unwanted ultraviolet energy that could otherwise be harmful to plastic components in the vicinity of automotive headlamps.

Although the foregoing discussion of xenon-metal halide lamps has been directed to automotive applications, it is to be understood that the present invention is equally applicable to a variety of other lighting applications. A significant feature of the light source of the present invention is that a large amount of instantaneous light is generated by the xenon inside the light source, which requires relatively large currents and relatively low voltages, after which the other constituents halides and mercury are ionized. - It evaporates, making it possible to lower the current and increase the voltage, resulting in a highly efficient light source. Due to the characteristics of instantaneous light and high efficiency, the light source of the present invention can be advantageously used in homes, offices, and various other commercial and industrial applications.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a motor vehicle headlamp according to the invention in which the light source is vertically oriented. FIG. 2 is a plan view schematically showing an automobile headlamp according to the invention in which the light source is oriented in the horizontal axis direction. Figures 3(A) and 3(B) respectively show the divergence (divergence) of the light beam generated in a filament light source when a reflector of the same size is used, and the smaller xenon-metal halide of the present invention. FIG. 4 is a diagram comparing the divergence of beams generated by light sources. Figures 4(A) and 4(B) show the spread of light from an incandescent bulb light source and the xenon light source of the present invention in order to achieve the same spread of light beams when the thickness of the reflector is reduced. - It is a diagram comparing the effects that appear depending on the spread of light from a metal halide light source. 5(A) and 5(B) are perspective views of a prior art rectangular automotive headlamp and a rectangular automotive headlamp according to one embodiment of the present invention, respectively. 10... Headlamp, 12... Reflector, 14...
・Lens, 16... Internal envelope (xenon-metal halide light source), 26... Focus, 30.32...
・Electrode, 42... Infrared reflective coating, 110...
- Conventional technology headlamp, 116...tungsten filament.

Claims (13)

[Claims] (1) A light source comprising an envelope having a pair of electrodes disposed a predetermined distance apart from each other, the envelope comprising: (A) xenon at a pressure in the range of about 2 atmospheres to about 15 atmospheres at room temperature; B) mercury in an amount ranging from about 2 mg to about 15 mg; and (C) sodium iodide, scandium iodide, thallium iodide, indium iodide, tin iodide, in an amount ranging from about 2 mg to about 10 mg. A light source characterized in that it contains a filling consisting of a mixture selected from the group consisting of dysprosium iodide, holmium iodide, thulium iodide, thorium iodide, cadmium iodide and cesium iodide. 2. The light source of claim 1, wherein the mixture comprises sodium iodide and scandium iodide in a molar ratio of about 19:1. (3) said inner envelope is comprised of (A) a material selected from the group consisting of glass and quartz; and (B) an elongate body having an overall length in the range of about 15 mm to about 40 mm; having opposed necks with diameters in the range of about 2 mm to about 5 mm, and a bulbous central portion with an inner diameter in the range of about 4 mm to 12 mm with a center outer diameter in the range of about 6 mm to about 15 mm. 2. The light source according to claim 1. (4) The arranged electrodes include tungsten and 1-
2. The method according to claim 1, comprising a pair of rod-like members made of a material selected from the group consisting of tungsten containing 3% thorium oxide, said rod-like members being electrically connected to respective lead wires. light source. (5) The light source according to claim 4, wherein the electrodes are arranged at both ends of the envelope. 6. The light source of claim 4, wherein the electrodes are both located at one end of the envelope. 7. The light source of claim 1, wherein the inner envelope is coated with a multilayer infrared reflective film. (8) The film is comprised of alternating layers of materials selected from the group consisting of: (a) tantalum oxide and silicon dioxide, and (b) titanium oxide and silicon dioxide.
Light source as described. (9) (A) a reflector plate having a predetermined focal length and focus having a portion associated with means connectable to an excitation source of the motor vehicle; (B) a lens associated with the front portion of said reflector plate; and (C) an automotive headlamp comprising an inner envelope disposed at a predetermined position within the reflector so as to be disposed near the focal point of the reflector, the inner envelope comprising mercury and a metal halide. Contains xenon filling at relatively high pressure,
It has a pair of electrodes separated by a predetermined distance from each other,
connected to said means associated with said portion such that said excitation source can be energized to act on said electrode, such that upon said action said xenon contained in said envelope is excited; and emit a large amount of light,
The mercury and metal halide are then excited, and the excitation of the xenon, mercury and metal halide results in a high intensity light source located between the electrodes. (10) The headlamp for an automobile according to claim 9, wherein the reflector comprises a parabolic rotating body having a focal length in a range of 6 to 35 mm. (11) The headlamp for an automobile according to claim 9, wherein the lens is made of a transparent member made of a material selected from the group consisting of glass and plastic, and the transparent member has a surface made of a prismatic member. . (12) said excitation source capable of being energized to affect said electrodes for an initial period of about 10 seconds, with a current of about 5 amps and a voltage of about 12 volts, excitation of said inner envelope at about 60 volts;
10. The motor vehicle of claim 9, wherein the internal envelope is operated at about 40 Watts, and then the current is gradually reduced to a value of about 1.4 Amps and the voltage is increased to a voltage of about 30 Volts. head lamp. (13) The high-intensity light source cooperating with the reflector is about 7
10. Motor vehicle headlamp according to claim 9, which produces a plurality of reflected rays that diverge from each other at angles of value less than .degree.