JPH0652829A - High pressure metal vapor discharge lamp - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] A small-sized external tube that does not damage the glass bulb due to internal pressure because the rising of the luminous flux at the start is quick and the glass bulb is not damaged by internal pressure. An object is to provide a high pressure metal vapor discharge lamp. [Structure] At least a pair of discharge electrodes 3 are disposed inside, and a sealing portion 2 is provided at both ends of a quartz glass bulb 1 having a circular shape, such as an elliptical shape, an oval shape, or a spherical shape, in which a metal halide and a starting gas are enclosed. In the discharge lamp having no outer tube, the maximum thickness Mx of the glass bulb 1 is 1.
The thickness of the minimum thickness portion Mn of 5 mm to 2.0 mm is characterized by being 0.8 mm to less than 1.5 mm in the maximum diameter portion in the direction orthogonal to the valve axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulb structure for a small high-pressure metal vapor discharge lamp without an outer bulb which is used for vehicle headlights such as automobiles and store lighting.

[0002]

2. Description of the Related Art Small-sized, highly efficient, long-life high-pressure metal vapor discharge lamps can be instantly turned on in place of filament light bulbs having filaments used for automobile headlights and store lighting. While the lighting circuit is being developed, commercialization is being promoted.

There are high-pressure metal vapor discharge lamps such as short arc metal halide lamps and xenon lamps as this type of discharge lamp, and these lamps do not have an outer tube made only of an elliptical or spherical arc tube made of quartz glass. As a compact light source, it has been started to be used for various purposes such as automobile headlights and store lighting.

For example, a conventional small-sized short arc metal halide lamp has a substantially elliptical shape (internal dimension long diameter of about 7 m).
Introducing bodies made of molybdenum foil or the like connected to a discharge electrode and an external conductor are oppositely sealed at both ends in the major axis direction of a quartz glass bulb molded to have a size of m × short diameter of about 4 mm). Inside the bulb, several mg of mercury and several mg of metal halide such as scandium iodide (ScI ₃ ), sodium iodide (NaI) and rare gas such as xenon are enclosed.

[0005] The discharge lamp is not enclosed in an outer tube, and the outer tube is not used, and the light emitting tube is used as it is by being mounted in a headlight of a vehicle or a store lighting fixture.

By the way, in a small discharge lamp used without an outer tube of this kind, good lamp characteristics (brightness) are obtained.
In order to obtain the above, it is necessary to reduce the glass thickness of the bulb to minimize the heat loss of the bulb against the input, and to keep the tube wall temperature around the electrode, which is the coldest part of the lamp during operation, high. Is desirable.

However, if the wall thickness is made thin in this way, the influence of the wind and temperature on the coldest part of the lamp becomes large, and the lamp characteristics fluctuate remarkably due to these changes. Further, when sealing the bulb using quartz glass and the introduction body such as molybdenum foil, heating is performed using an oxyhydrogen burner, so that if the thickness of the glass is thin, undesired deformation occurs and the appearance deteriorates. Occurs.

Further, for automobiles and the like, since it is necessary to raise the luminous flux within a short time after the lamp is started, the pressure of the rare gas filled in the bulb is several atmospheric pressure or more at normal temperature and several tens of atmospheric pressure or more when the operation is stable. Although it is necessary to maintain it, there is a problem that when the glass wall thickness is reduced, the pressure cannot be withstood and the valve bursts. The rupture of the bulb occurs near the vicinity of the sealing portion having a relatively large curvature, and it is expected that not only the lamp will be worn but also the lighting device will be damaged and a serious accident to human body will be caused. On the contrary, if the glass thickness is made too thick in consideration of damage, the glass absorbs light and absorbs heat to lower the light efficiency.In addition, it takes a long time to raise the temperature and the start-up of the luminous flux is slow, so that the brightness of the automobile is not immediately high. Not suitable if needed.

[0009]

The problems to be solved are that the internal pressure of the glass bulb becomes high and the bulb is damaged, and the rise of the luminous flux at the time of starting is slow and the light efficiency is low.

The present invention has been made in view of the above circumstances, in which the luminous flux rises quickly at the time of starting and the light efficiency (l
It is an object of the present invention to provide a high pressure metal vapor discharge lamp having an improved m / W) and improved pressure resistance so that the glass bulb is not damaged by the internal pressure.

[0011]

A high pressure metal vapor discharge lamp according to claim 1 of the present invention has a circular shape in which at least a pair of discharge electrodes are disposed and a metal halide and a starting gas are enclosed. In a discharge lamp without an outer tube in which sealing parts are formed at both ends of a quartz glass bulb, the maximum thickness of the glass bulb is 1.5 mm to 2.0 mm, and the minimum value is the maximum diameter in the direction orthogonal to the bulb axis. 0.8 mm to 1.5
It is characterized by being less than mm. The high-pressure metal vapor discharge lamp according to claim 2 of the present invention is characterized in that the quartz glass bulb has a circular shape such as an elliptical shape, an oval shape, or a spherical shape.

In the high pressure metal vapor discharge lamp according to claim 3 of the present invention, the pressure of the starting gas sealed in the glass bulb is 3 to 15 atm at room temperature and 10 to 15 when the discharge is stable.
It is characterized by being 0 atm.

[0013]

[Function] The outer diameter of the circular quartz glass bulb, which is used without an outer tube and has sealing portions formed at both ends, can be thinned to obtain sufficient brightness at the maximum diameter portion with the highest light emission and to have a relatively high curvature. By increasing the wall thickness in the vicinity of the large sealed area, it is possible to prevent the bulb from bursting and the temperature of the bulb from fluctuating due to changes in the atmosphere, thus improving the pressure resistance and the lamp characteristics.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. The drawing shows a short arc metal halide lamp of rated power of 50 W or less according to the present invention, for example, 35 W, in which 1 is a maximum diameter part inner diameter in the direction orthogonal to the tube axis made of quartz glass of about 4 mm, and an inner maximum in the tube axis direction. 7m long
m is a valve having a substantially elliptical shape, and reference numerals 2 and 2 are crushing sealing portions provided at extension portions at both ends on the tube axis of the valve. In each of the sealing parts 2 and 2, as an introduction body, a discharge electrode 3 made of a tungsten wire having a diameter of about 0.3 mm is provided at one end, and an outer conductor 4 made of a molybdenum wire having a diameter of about 0.5 mm is provided at the other end. A molybdenum foil 5 having a width of about 1 mm, a thickness of about 25 μm, and a length of about 12 mm, which is welded, is buried in an airtight manner.

The glass wall thickness of the bulb 1 is about 1.0 mm, which is the thinnest in the maximum diameter portion in the direction orthogonal to the tube axis, and goes from the maximum diameter portion Mn to the sealing portion 2 in which the discharge electrode 3 is embedded. The maximum thickness is about 1.8 mm.

Further, about 1 mg of mercury, about 1 mg of scandium iodide (ScI ₃ ) and sodium iodide (NaI) having a composition ratio of 1: 5 and about 5 atm of xenon as a starting gas are enclosed in the bulb 1. ing.

Reference numeral 6 is a heat insulating film made of aluminum oxide (Al ₂ O ₃ ) or the like, which is covered from the bulb 1 around which the discharge electrode 3 is embedded to the vicinity of the sealing portion 2,
The vicinity of the sealing portion 2 is kept warm to improve the lamp characteristics.

A lamp having such a structure is lit at an rated temperature of 35 W in an atmosphere of 20 ° C. and various lamp characteristics are measured, and a 20% increase in rating of 42 W is lit for 3 hours, and a blinking test for 30 minutes is off for 1500 hours. However, there was no decrease in brightness, deformation of the sealing part, or rupture of the glass bulb.

Example 1 A short arc metal halide lamp having a rated output of 35 W was manufactured under the same conditions as described above except for the wall thickness of a glass bulb, and a comparative test was conducted. The following results were obtained. The wall thickness of the glass bulb of these lamps is constant at the maximum wall thickness Mx of 1.8 mm in the vicinity of the sealing portion, and the minimum wall thickness Mn is 0.6 mm at the maximum diameter portion in the direction orthogonal to the tube axis. .8 mm,
Ten lamps each having a size of 1.0 mm, 1.2 mm, 1.5 mm and 1.8 mm were manufactured.

FIG. 2 shows the rupture occurrence status of the bulbs as a result of conducting the flashing test of the efficiency (lm / W) of each of these lamps at 42W, which is an increase of 20% of the rating, for 42 hours and the lighting for 30 minutes, and then extinguished for 30 hours. there were.

The appearance of the bulb near the sealed portion was visually observed after the crushing and sealing work of each of these lamps, but no deformation occurred.

In addition, these lamps were
The lamp voltage, current, and luminous flux characteristics are 3% within the measurement error range when the lamp is turned on at the rated temperature of 35W at ambient temperature of 25 ℃.
There was no problem with the degree.

Example 2 A short arc metal halide lamp having a rated output of 35 W was manufactured under the same conditions as in Example 1 except for the thickness of the glass bulb, and a comparative test was conducted. The following results were obtained. The thickness of the glass bulbs of these lamps is kept constant at 1.2 mm at the minimum thickness portion Mn at the maximum diameter portion in the direction orthogonal to the tube axis, and the maximum thickness portion Mx is 1.0 mm near the sealing portion.
Ten lamps each having a size of 1.2 mm, 1.5 mm, 1.8 mm, and 2.0 mm were manufactured.

A flashing test of the efficiency (lm / W) of each of these lamps, the occurrence of bulb deformation in the vicinity of the sealing portion during crushing and sealing work, and a 20% increase in rating of 42 W for 3 hours and 30 minutes of extinguishing was performed. The state of occurrence of valve rupture as a result of 1500 hours was as shown in FIG.

Also, these lamps were
When the lamp was turned on at the rated 35 W at the ambient temperature of 25 ° C., the lamp voltage, current, and luminous flux characteristics were about 3% within the measurement error range, and there was no problem.

From the above Examples 1 and 2, it was found that the present invention can improve the lamp characteristics and the pressure resistance of the glass bulb which becomes a high pressure during lighting by controlling the thickness of the quartz glass bulb. The wall thickness of this glass bulb is such that if the maximum diameter portion in the direction orthogonal to the tube axis is 0.8 mm or more, the pressure resistance can be maintained and the bulb can be prevented from bursting, and the thickness is 1.5 mm.
If it is less than the above value, the brightness (target efficiency of 70 lm / W or more) is not significantly reduced and is not suitable for practical use.

If the wall thickness in the vicinity of the sealing portion is 1.5 mm or more, it will not be deformed when heated by a gas burner or the like during the sealing work, but if the wall thickness is too thick, light is absorbed and the luminous flux The length is preferably 2.0 mm or less because of a decrease in the temperature, a rise in the luminous flux due to insufficient temperature rise at the start of the lamp, and a large amount of time and energy required for heating during the sealing work.

Further, in manufacturing the glass bulb having the thickness distribution as in the present invention, for example, the central portion of a quartz glass tube having a thickness of 1.8 mm is heated, and the heated glass tube is provided with an elliptical recess. A valve having an elliptical shape with a thinnest maximum diameter portion can be obtained by inserting the mold into two molds and blowing high-pressure gas into the pipe.

Furthermore, the inert gas filled in the discharge lamp of the present invention is not limited to xenon having a light emitting property, but may be a single substance or a mixture such as argon or krypton.
No rupture of the bulb was observed up to a pressure of 3 to 15 atm at room temperature and 10 to 150 atm during stable lighting.

The present invention is not limited to the above embodiment. For example, the tube is not limited to a short arc metal halide lamp, but may be a xenon lamp or the like, and its bulb shape is not limited to the substantially elliptical shape shown in the figure, and may be an oval shape or a circular shape such as a spherical shape.

Further, the luminescent substance sealed in the bulb is not limited to ScI ₃ and NaI in the above-mentioned embodiment, but Dy, Tm, H.
It may be a halide such as o or Cs.

Further, the sealing portion is not limited to the crushing sealing using the pressing die, and of course, a vacuum or a reduced pressure sealing of an inert gas can be applied.

Furthermore, as long as the thickness of the glass bulb is within the above range, the same results as in the above embodiment can be obtained even when the size and material of the discharge electrode, the composition of the metal halide, and the amount of filling are changed. It was applicable.

[0034]

As described above in detail, according to the present invention, in a small-sized high-pressure metal vapor discharge lamp used without an outer tube, the thickness of the circular quartz glass bulb is the bulb axis with the most light emission. Since the maximum diameter part orthogonal to is thinnest and the sealing part where internal stress is applied most is thickest, the lamp efficiency is improved and the pressure resistance of the glass bulb that becomes high pressure during lighting can be improved and the bulb is prevented from bursting. Also, since there is no undesired deformation due to the heating burner in the vicinity of the sealing portion, it is possible to provide a discharge lamp having an excellent appearance.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a high pressure metal vapor discharge lamp of the present invention.

FIG. 2 is a corresponding diagram showing characteristics and test results of the discharge lamp according to the present invention.

FIG. 3 is a corresponding diagram showing characteristics and test results of the discharge lamp according to the present invention.

[Explanation of symbols]

 1: Quartz glass bulb Mn: Minimum bulb thickness Mx: Maximum bulb thickness 2: Sealing portion 3: Discharge electrode 5: Molybdenum foil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Ito 1-4-2 Mita, Minato-ku, Tokyo Toshiba Lighting & Technology Corporation

Claims (3)

[Claims] 1. A discharge lamp without an outer tube, wherein at least a pair of discharge electrodes are provided inside, and a circular quartz glass bulb in which a metal halide and a starting gas are sealed has a sealing portion formed at both ends thereof. The glass bulb has a maximum thickness of 1.5 mm to 2.0 mm and a minimum thickness of 0.8 mm to less than 1.5 mm in a maximum diameter portion in a direction orthogonal to the bulb axis. Discharge lamp. 2. The quartz glass bulb has a circular shape such as an elliptical shape, an oval shape, and a spherical shape.
High-pressure metal vapor discharge lamp according to. 3. The pressure of the starting gas sealed in the glass bulb is 3 to 15 atm at room temperature and 10 to 1 at stable discharge.
The high pressure metal vapor discharge lamp according to claim 1, wherein the pressure is 50 atm.