JP3213181B2 - Discharge lighting device, automotive headlamp device, and method for generating light output - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION The present invention relates to a discharge lighting device which is particularly suitable for front lighting of vehicles such as passenger cars, trucks, buses, vans or tractors. More specifically, the discharge lighting device of the present invention is a discharge lighting device for an automobile headlamp having an instantaneous lighting ability, a relatively long life and a relatively high efficiency.

[0002] Automotive designers are interested in lowering passenger car hood lines in order to improve the appearance of the car and improve aerodynamic performance.
No. 157,359 (1) related to the present invention.
988), the extent to which the hood line can be lowered is limited by the size of the vehicle's headlamp, which is typically the size of the light source itself, which is typically composed of tungsten filament. Limited by

[0003] As disclosed in US Patent Application No. 157,359, the overall size of a vehicle headlamp reflector is provided by a xenon discharge light source having dimensions substantially reduced as compared to a tungsten light source. This allows the car designer to lower the car's hood line considerably.
In addition, the xenon discharge light source disclosed therein has an instantaneous lighting start capability similar to that of a tungsten filament, and is therefore particularly suitable for automobile use.

[0004] Although xenon light sources exhibit their desired function, they have the disadvantage that their efficiency is inferior to 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, of the order of 15 volts. For this reason, most of the energy consumed in such a xenon lamp is wasted by the electrodes of the xenon lamp and does not contribute to the light output. Another cause of this low efficiency is that the xenon spectrum contains a relatively large amount of infrared energy, which does not serve a useful purpose for automobiles, and which is not suitable for automotive headlamp plastic. It is also harmful to the plastic housing.

It would be desirable to provide a discharge lamp such as a metal halide lamp to meet the needs of automotive headlamps. It is also desirable that the metal halide lamp has almost instantaneous light output capability like a xenon lamp or a tungsten incandescent light source. Furthermore, in addition to metal halide lamps that meet the needs of the automotive industry, it is desirable that metal halide lamps find use in homes, offices, and other commercial and industrial lighting applications. Accordingly, it is an object of the present invention to provide a metal halide discharge light source for lighting that is particularly suitable for meeting the needs of the automotive industry in the sense of substantially instantaneous lighting.

Yet another object of the present invention is desirable for vehicles having relatively small dimensions which reduce the size of the associated reflector of the headlamp, and thus have an aerodynamically adapted style. An object of the present invention is to provide a metal halide discharge lamp in consideration of a reduction in a hood line. SUMMARY OF THE INVENTION The present invention relates to a xenon-metal halide discharge light source having a variety of lighting applications and particularly suitable for automotive headlamps.

In one embodiment, an automotive headlamp comprises a reflector, a lens, and an inner envelope. The reflector has a part associated with a means that can be connected to the excitation source of the motor vehicle. The reflector also has a predetermined focal length. The lens of the automotive headlamp is associated with the front of the reflector. The internal envelope of the vehicle lamp is installed at a predetermined position inside the reflector so as to be located near the focal length of the reflector. The inner envelope contains a relatively high pressure xenon charge, a certain amount of mercury and a metal halide (metal halide). The inner envelope has a pair of electrodes separated from each other by a predetermined distance. The inner envelope is connected to a means associated with the linking portion of the motor vehicle lamp so that the excitation source can be energized and act on the electrodes, and when energized, the inner envelope is housed within the inner envelope. The xenon filling is excited to emit a large amount of light, followed by the evaporation and ionization of mercury along with the metal halide components. The ionization of xenon and metal halide creates a high intensity, high efficiency light source between the electrodes. DETAILED DESCRIPTION Figure 1 of the preferred embodiment is a side view showing an outline of an automotive headlamp 10 according to one aspect of the present invention, the headlamp is made from the reflection plate 12, the lens 14 and the internal envelope 16.

The reflector 12 comprises a connector 20 with prongs 22, 24 which can be connected to the excitation source of the vehicle.
A rear portion 18 is provided with such means. The reflector 12 has a predetermined focal length 26 along an axis 28 of the vehicle headlamp 10. The reflector 12 has a parabolic shape, and its focal length ranges from about 6 to about 35 mm, preferably from about 8 to about 20 mm. The lens 14 fits on the front of the reflector 12. The 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 by a prism member.

The inner envelope 16 is installed at a predetermined position in the reflector and has a focal length 26 of the reflector.
It is placed near. In the embodiment shown in FIG. 1, the inner envelope 16 is oriented perpendicular to the axis 28 of the reflector 12, whereas FIG. The inner envelope 16 is shown oriented along.

The inner envelope 16 depicted in FIGS. 1 and 2 is double-headed and has a pair of electrodes 30, 32;
The electrodes are located opposite the neck of the inner envelope and are separated from each other by a predetermined distance in the range of about 2 to about 4 mm. This inner envelope 16 has both electrodes located at one end of the lamp,
The single-head type may be separated from each other by a predetermined given range. The pair of electrodes is preferably tungsten,
And a rod-shaped member formed of a material selected from the group consisting of tungsten containing 1 to 3% of thorium. In one embodiment of the inner envelope made of quartz, the rod-shaped electrodes are connected to foil members 34, 36 enclosed in opposing necks of the inner envelope, respectively. These foil members 34, 36 are connected to relatively thick internal leads 38, 40, which are connected to prongs 22, 24, respectively. Preferably, General Electric (General
In another embodiment for a # 180 type glass inner envelope available from Electric Company), a rod-shaped tungsten electrode can be welded to a molybdenum lead that can be directly encapsulated in # 180 glass.

The electrodes 30 and 32 are connected to Davenpo
rt) et al., of the spot mode type disclosed in U.S. Pat. No. 4,574,219, which is incorporated herein by reference. U.S. Patent No. 4,
The spot mode electrode coated with the cement material disclosed in Table 3 of U.S. Pat. No. 5,574,219 emits thermionic electrons and almost instantaneously establishes the conditions necessary to produce a thermionic arc condition within the inner envelope 16. Form.

The inner envelope 16 comprises an elongated body having a total length in the range of about 15 to about 40 mm, a neck having a diameter of about 2 to about 5 mm, and a bulbous central portion having a diameter of about 6 to about 15 mm. It has a central part. This inner envelope 16 preferably has a coating 4 on its outer surface.
2, the coating preferably being a multilayer infrared-reflective film consisting of alternating layers of tantalum oxide and silicon dioxide, or titanium oxide and silicon dioxide. This multilayer infrared reflective film reflects the infrared energy emitted from the lamp toward the lamp arc so that the arc temperature is maintained without increasing the input from the excitation source. By doing so, the efficiency of the operating lamp 16 (described below) is improved.
This infrared reflective coating 42 is also advantageous in that it absorbs the UV energy of the lamp 16 incidentally. If this ultraviolet energy is not absorbed in this manner, it will cause deterioration of the plastic parts and other parts of the headlamp 10. This process of absorbing ultraviolet electromagnetic energy and reflecting infrared electromagnetic energy has the additional benefit of increasing the heating rate of the lamp 16,
This speeds up the evaporation and ionization of the mercury and metal halide inside the lamp 16 and consequently reduces the lamp start-up time when the xenon-metal halide lamp 16 is operated with high pressure xenon.

The filling contained in the xenon-metal halide lamp 16 consists of xenon, mercury and metal halide. The xenon charge has a fill pressure ranging from about 2 atmospheres to about 15 atmospheres at room temperature. xenon-
About 2mg of mercury contained in metal halide lamp
Amounts range from about 10 mg to about 10 mg. This amount of mercury is such that when a bulb of a certain size and a certain distance between the electrodes is used, the voltage drop across the lamp is a convenient value, and the convection current in the lamp that causes arc bending is excessive. Is selected so as not to cause bending. Operating pressures range from about 3 to about 100 atmospheres as a result of the presence of both xenon and mercury. The metal halide is a mixture in an amount ranging from about 4 mg to about 12 mg. This mixture consists of a halide selected from the group listed in Table 1.

[0014]

An example of TABLE 1 preferred selection of components on sodium iodide scandium iodide thallium iodide indium iodide tin iodide dysprosium iodide iodide, holmium iodide, thulium iodide, thorium iodide cadmium cesium iodide, about It is a mixture of sodium iodide and scandium iodide in a molar ratio of 19: 1. The xenon-metal halide lamp 16 of the present invention comprises:
Particularly suitable for use as a light source for vehicle front lighting.

First, when an excitation source is applied to the electrode of the xenon-metal halide lamp, the xenon filling is instantaneously ionized and emits light. Thereafter, when the operation of the excitation source is continued, mercury evaporation and ionization are performed together with the metal halide. Occur. The amount of instantaneous light varies linearly with the pressure of xenon in the inner envelope. Xenon-metal halide lamp The xenon component of the envelope acts to give sufficient instantaneous light for automobiles, while the mercury and metal halide components act to produce discharge lamps and tungsten filaments containing only xenon for automobiles. Ensures higher efficiency long life headlamps compared to lamps. In a xenon-metal halide light source having a relatively short distance between the electrodes of 3 mm, the xenon gas starts the lighting substantially instantaneously (lighting), so that light output suitable for an initial automobile can be obtained. The xenon-metal halide lamp warms up sufficiently in less than 30 seconds, and high efficiency output is guaranteed by ionization of mercury and metal halide.

In order to operate the xenon-metal halide lamp in a cold (room temperature) state, a current of 5 amps at a voltage of 12 V is supplied to the lamp to operate at about 60 watts. As the mercury and metal halide in the lamp ionize and evaporate, the voltage across the lamp gradually increases to about 40 volts, so
Adjust the current to about 1 amp to operate at 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 is condensed (liquefied) like the metal halide.
However, this lamp operates essentially as a high pressure xenon lamp. During such an initial state, the high intensity light spot is confined in front of one of the electrodes, resulting in a medium area brightness. When the xenon-metal halide lamp 16 is sufficiently warmed, the xenon emission gradually increases due to the emission of mercury and metal halide. As the voltage across the lamp begins to increase and the current flowing through the lamp begins to decrease, the electrode losses of the metal halide lamp are reduced and the efficiency of the lamp is correspondingly improved.

In the practice of the present invention, a 19: 1 molar ratio of sodium iodide and scandium iodide together with the amount of mercury required to produce a voltage drop of about 30-50 V and xenon at a fill pressure of 5 atmospheres. Used successfully for xenon-metal halide lamps sized to meet the needs of the automotive industry. The lamp can be mounted on a motor vehicle according to one aspect of the present invention. It is also advantageous to select other metal halides, which can be of a color that is advantageous for automobiles.

The xenon-metal halide lamps of the present invention using high pressure xenon provide sufficient light in the first few seconds of lamp operation to meet the needs of automotive lighting. After the first few seconds, the mercury and metal halide components inside the inner envelope increase the discharge of xenon, ensuring a highly efficient light output. Automotive headlamp 1 of the present invention
0 can satisfy the lighting needs for low beams (downward rays) for automobiles when the xenon-metal halide lamp is excited with a voltage of 30V and a current of 1.4A.
The same excitation will provide illumination for the high beam (upward beam).

One of the advantages of the high efficiency metal halide lamp according to the present invention is that, due to its relatively small arc size, the size of the reflector housing the metal halide lamp is reduced to form a headlamp for an automobile. Is possible, so that it is possible to lower the hood line of the automobile described in the section "Background of the Invention". The manner of such reduction can be explained with reference to FIGS. 3A and 3B.

FIGS. 3A and 3B are interrelated and show a beam opening produced by a headlamp using a tungsten filament 116 having a smaller xenon-metal halide light source 16 of the present invention. It is a figure shown in comparison with the degree of opening of a beam generated in a headlamp. FIG. 3A shows a light source 116 represented by an arrow whose center is located at a focal point 26 along an axis 28 of the reflector 12, while FIG.
The figure shows a xenon-metal halide light source 16 represented by an arrow whose center is located at a focal point 26 along an axis 28 of the reflector 12 having the same dimensions as in FIG. 3A. The incandescent light source 116 has a typical length of the order of 5 mm, whereas the xenon-metal halide light source 16 is approximately 3 mm long.

This incandescent lamp filament 116 is activated.
Will produce multiple reflected rays that will be reflected by the light source
The angle θ is proportional to the size of 116_AThe percentage represented by
Diverging (opening). Similarly, Xenon-Metal Harai
Light sources 16 have an angle θ with each other. _BRays diverging at
Emits. Referring to FIG. 3A, the filament
The angle of the opening of the light from the
Ray 116 emitted from the top part_AIs due to the reflector 12
Ray 116 blocked and reflected by_BIndicated by
Have been. Ray 116 through focal point 26_BBetween shaft 28
Is the opening angle θ of the light from the filament 116._AIn
You. Filament 116 (5 mm) and reflector 12 (focus
Using the values already mentioned for 25 mm),
Angle θ_ABecomes 11.3 °.

FIG. 3B illustrates a ray 16 similar to rays 116 _A and 116 _B described with respect to FIG. 3A.
_A and _16B are shown. The opening angle θ _B caused by the light emitted from the xenon-metal halide light source 16 is
For the values of the light source 16 (3 mm) and the reflector 12 (focal length of 25 mm), the value is 6.80. Aperture angle θ
_B is approximately 3/5 of the opening angle θ _A. 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 automotive headlamp 10 toward the road is less divergent and therefore needs to illuminate the road. Means that less light goes where there is no need for more light. The xenon-metal halide light source 16 of the present invention reduces this spread or unwanted light as compared to the incandescent light source 116, resulting in a reduced fog, rain and snow bale or concealment effect, thereby making the direct light more useful for automotive applications Is obtained.

Xenon-metal halide light source 1 of the present invention
Another advantage provided by the relatively small size of 6 is that
This is to reduce the required size of the reflector of the automotive headlamp, which can be explained with reference to FIGS. 4A and 4B. 4 (A) and FIG. 4 (B) are respectively shown in FIG. 3 (A) and FIG. 3 (B).
Similar to the figures, where similar reference numerals are used where applicable. 4 (A) and FIG. 4 (B), the focal length 26 is half that of the focal length 26 shown in FIGS. 3 (A) and 3 (B). The points are different.
Further, the height of the reflector 12 shown in FIGS. 4A and 4B is about ２ of that of the reflector 12 shown in FIGS. 3A and 3B. Has decreased.

FIG. 4A shows a tungsten incandescent lamp.
Filament 116_AAnd 116_BDepart
This light 116_BIs the opening angle θ_C
Are formed, and the angle of the focal length is 12.5 mm.
In the case of the reflector shown in FIG. 4A and FIG.
Using the value of filament 116 described above (length 5 mm)
The value is about 21.8 °.
Stray light is generated in a sufficient amount of beam pattern
Nevertheless, such stray light meets the needs of automotive technology.
Not. On the other hand, FIG._AAnd 16
_BXenon-metal halide with a length of about 3 mm
A light source 16 is shown. _BIs about 13.5
Opening angle θ with a value of °_DAnd the result is automatic
Stray light to be more advantageous than meeting the needs of car technology
A limited amount of beam pattern results. Smaller rhino
Xenon-metal halide light source 16
As a result, the focal length of the reflector 12 is reduced, and
Reflector due to a little smaller but overall size reduced
Light collection efficiency can be increased. The overall effect is xenon-
Metal halide light source reduces reflector size
And improve the light collection efficiency of the reflector to a sufficient degree.
Therefore, as discussed in the “Background of the Invention” section,
Car designers can lower the car hood line
I will be able to. By implementing the present invention, an automobile head
Uses regular incandescent bulb filament for lamp reflector
2/3 smaller than conventional automotive headlamps
And, accordingly, the vehicle
Lower the code line.

The total amount of reduction in the size of the reflector and the corresponding reduction in the size of the vehicle headlamp can be shown with reference to FIGS. 5A and 5B. FIG. 5A is a perspective view illustrating a prior art rectangular automotive headlamp using an incandescent bulb filament and having similar elements to the automotive headlamp 10 of FIGS. 1 and 2; Corresponding reference numerals are given in the hundreds. FIG. 5B is a perspective view illustrating one embodiment of the present invention, which is the rectangular automobile headlamp 10 shown in FIG. 1 and FIG. As stated in the description, about 40% compared to the prior art lamp 100
is decreasing. Prior art lamp 10 shown in FIG.
As can be readily seen by comparing the lamp 10 of the present invention in FIG. 5 with the lamp 10 of FIG. 5 (B), the practice of the present invention allows a car designer to significantly lower the hood line of a car, including a xenon-metal halide. Lamp 16
Means can be obtained.

The realization of a xenon-metal halide lamp according to the present invention not only provides instantaneous light that satisfies the needs of automobile lighting, but also reduces the hood line of the automobile due to its reduced size.
Therefore, the aerodynamic style that car designers want is possible. Xenon of the present invention
Metal halide lamps are also expected to have a relatively long life of 5,000 hours, thus meeting the need for longer life expectancy for automotive headlamps.

Still further, the infrared multilayer film coating provided outside the xenon-metal halide lamp inner envelope increases the efficiency of the xenon-metal halide lamp by reflecting the infrared light toward the arc of the xenon-metal halide lamp, and It should be understood that this reduces undesirable ultraviolet energy that could otherwise be detrimental to plastic components near the automotive headlamp.

Although the above description of xenon-metal halide lamps has been for automotive applications, it is to be understood that the invention is equally applicable to various other lighting applications. An important feature of the light source of the present invention is that
A large amount of immediate light is generated by xenon inside the light source, which requires a relatively large current and a relatively low voltage, after which the other components halide and mercury ionize and evaporate,
It is possible to obtain a light source with high efficiency by enabling a reduction in current and an increase in voltage. The light source of the present invention is characterized by its instantaneous light and high efficiency, and can be advantageously used in homes, offices, and various other commercial and industrial applications.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing an automotive headlamp of the present invention in which a light source is vertically oriented.

FIG. 2 is a plan view schematically showing an automotive headlamp of the present invention in which a light source is oriented in a horizontal axis direction.

FIGS. 3 (A) and 3 (B) show the xenon-metal halide of the present invention, respectively, in which the light beam divergence and divergence generated by the filament light source when the same size reflector is used are smaller. It is the figure which compared the opening of the beam generated by the light source.

FIGS. 4A and 4B are diagrams showing the opening of light from an incandescent lamp light source and the xenon of the present invention in order to make the same light beam opening when the size of the reflector is reduced. It is the figure which compared the influence which appears on the opening of the light from a metal halide light source, respectively.

FIGS. 5A and 5B are perspective views of a prior art rectangular vehicle headlamp and a rectangular vehicle headlamp according to one embodiment of the present invention, respectively.

[Explanation of symbols]

Reference Signs List 10 headlamp 12 reflector 14 lens 16 inner envelope (xenon-metal halide light source) 26 focus 30, 32 electrode 42 infrared reflective coating 110 prior art headlamp 116 tungsten filament

────────────────────────────────────────────────── ─── Continuation of the front page (72) Richard Lowell Hansler, Inventor, Bellevue Road, Pepper Pike, Ohio, USA, No. 28120 (56) References JP-A-54-86979 (JP, A) JP-A-54-162874 (JP, A) JP-A-56-76157 (JP, A) JP-B 5-50097 (JP, B2) JP-B-33-10097 (JP, B1) (58) (Int.Cl. ⁷ , DB name) H01J 61/20 H01J 61/16 H01J 61/88

Claims (2)

(57) [Claims] A discharge lamp having a vitreous envelope, wherein a pair of electrodes are provided within the vitreous envelope.
Mercury, a mixture of a metal halide, and a rare gas are included, and the pair of electrodes is connected to a power supply for supplying excitation energy to the discharge lamp. Xenon at a pressure in the range of 2 to 15 atm at room temperature is included as the noble gas in the discharge lamp, and the power supply means operates during the initial warm-up operation step of warming up the lamp during subsequent steps of the lamp. A power supply for supplying a larger amount of current and power to the discharge lamp than the current and power for maintaining the lighting operation of the lamp during the steady operation stage
A stage, current and power during the initial warm-up phase of operation, together to excite the xenon to produce a sufficient instantaneous light emission in automotive headlamp applications, current and power during the steady operation step, An automotive headlamp device wherein the mercury and the metal halide are ionized to produce a sustained light sufficient for automotive headlamp applications. 2. The headlamp apparatus according to claim 1, wherein a current during the initial warm-up operation stage is five times larger than a current during the steady operation stage.