JP2003086131A - Metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal halide lamp causing little heat loss, capable of restraining of light-emitting material contributing to light emission and having high efficiency and a long service life. SOLUTION: This metal halide lamp has an arc tube 1 made of translucent ceramics having: a luminescent part 3 having a pair of electrodes 9 and 10 formed inside, and filled with the light-emitting material 11 containing at least one kind of cerium (Ce) and praseodymium (Pr); thin tube parts 4 and 5 formed at both ends of the luminescent part 3; and power feeding bodies 6 and 7 enclosed in the tube parts 4 and 5 and connected to the electrodes 9 and 10. The luminescent part 3 is so structured that the ratio of the minimum thickness of the luminescent part 3 to the maximum thickness of the luminescent part 3 is 0.80 or above, and the luminescent part 3 is molded integrally with the tube parts 4 and 5.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a metal halide lamp.

[0002]

2. Description of the Related Art In recent years, the development and development of a metal halide lamp using a translucent polycrystalline alumina ceramic tube instead of quartz as an arc tube material has been actively promoted. Since the heat resistant temperature (1200 ° C.) of this alumina ceramic tube is higher than the heat resistant temperature (1000 ° C.) of conventionally used quartz, the bulb wall load of the arc tube can be set higher and therefore the lamp efficiency is higher. A metal halide lamp is obtained. Up to now, a low wattage lamp with a lamp input of 70 to 150 W for general indoor lighting has been developed and released, but in the future, it will be 200 to 100% for general outdoor lighting.
A high wattage type of 1000 W is also strongly demanded by the market.

In a metal halide lamp using an alumina ceramic tube of a low watt type, which has been released for indoor lighting such as a storefront, for example, in the case of 150 W type, the lamp efficiency is 90 lm / W, the average color rendering index Ra90, and the rated life time 6000. The excellent characteristic of time is obtained.
However, the "life time" is that the luminous flux of the lamp is 100
It is the aging time when the initial value in time is reduced to 70%.

FIG. 8 is a sectional view showing the structure of the arc tube of such a lamp. The arc tube 115 is a light emitting part 11 which is a discharge arc region made of a polycrystalline alumina ceramic material.
6 and thin tube portions 117 and 118 provided at both ends thereof. The light emitting portion 116 and the thin tube portions 117 and 11
8 is integrated by shrink fit. Light emitting part 11
Inside the 6, a pair of tungsten electrodes 119 and 120 are provided. The thin tube portions 117 and 118 are provided with a power feeding body 12 made of niobium or a conductive cermet.
1, 122 are hermetically sealed by the frit, and the power feeding body 12
The above-mentioned tungsten electrode 1 is provided at the tip of the discharge side of Nos. 1 and 122.
19, 120 extended electrode rods are connected. In the arc tube _{115, DyI 3, TmI 3,} HoI 3, Tl
A luminescent substance made of a metal halide such as I and NaI, and a starting rare gas such as mercury and argon as a buffer gas are enclosed.

A low wad using the above alumina ceramic tube.
The arc tube shape of the Tometal halide lamp is basically
A conventional quartz arc tube metal halide lamp for interior lighting
Is almost the same as. That is, for example, with the configuration of FIG.
Typical dimensions of 150 W type alumina ceramic arc tube
As a method, the distance Le between electrodes is 10 mm and the pipe inner diameter is φ _i
Is 10.6 mm, which represents the shape of the arc tube in this case.
The so-called arc tube shape parameter L, which is an important parameter
e / φ_iThe value becomes 0.94. Also, when the lamp is on
The tube wall load we of the arc tube is 27 W / cm.²Is. However
Then turn the lamp watts to W_laAnd the inner surface area of the arc tube by S_aWhen
Then, the tube wall load we is we = W_la/ S_aStipulated by
Be done.

On the other hand, in the typical 150 W type of the conventional quartz arc tube lamp, the inter-electrode distance Le is 13.5 mm, the tube inner diameter φ _i is 13 mm, and the Le / φ _i value is 1.04. , Both arc tube shape parameters Le /
The φ _i values are set to almost the same level. in this way,
The emission shape of conventional low watt type alumina ceramic and quartz arc tube metal halide lamps for indoor lighting is
It can be said that both are relatively thick and short.

In addition, a so-called short arc type metal halide lamp of 20 to 250 W type using an alumina ceramic tube is disclosed in JP-A-10-144261. The characteristic of this lamp is that, as shown in FIG. 9, the discharge light emitting portion of the arc tube 123 has a cylindrical central portion 1.
24 and hemispherical ends 125 and 126. Here, the arc tube shape parameter Le /
The φ _i value is defined in the range of 0.66 to 1.25 corresponding to the low wattage type for indoor lighting of FIG. 8, while the tube wall load we is defined in a relatively high range of 25 to 35 W / cm ^2. Has been done. As described above, this lamp can be classified as a short arc type high pressure discharge lamp for special lighting, and the arc tube shape is thick and short like the low watt metal halide lamp for indoor lighting. Further, above the light-emitting substance similar to _{DyI 3, TmI 3, HoI 3} , TlI, metal halide materials such as NaI are sealed.

On the other hand, the arc tube shape of a high efficiency metal halide lamp for general outdoor lighting using an alumina ceramic tube is disclosed in US Pat. No. 5,973,453. In this lamp, a cerium halide-based substance that emits an emission spectrum in a wavelength region with high relative luminous efficiency is enclosed as a light-emitting substance for obtaining high efficiency of the lamp. As a specific luminescent substance, cerium iodide (CeI ₃ ) and sodium iodide (NaI) are encapsulated in a molar composition ratio NaI / CeI ₃ = 3 to 25, whereby a 150 W type is 130 lm / The characteristics of high lamp efficiency of W and the average color rendering index Ra58 are obtained. In this case, the Le / φ _i value of the arc tube shape parameter is defined in the range of Le / φ _i > 5 in order to achieve the high efficiency and long life required for general outdoor lighting. As will be described later, this arc tube shape is an elongated shape common to conventional high pressure sodium lamps and metal halide lamps for general outdoor lighting. The tube wall load we is specified to be 30 W / cm ² or less.

The alumina ceramic tube was invented and developed.
The first application as an arc tube material was the general outdoors
It is a high pressure sodium lamp for lighting. Again, al
Taking advantage of the above-mentioned features of the mina ceramic tube, for example, 40
Although the average color rendering index Ra25 of the 0W type is relatively low,
, Lamp efficiency about 140 lm / W and rated life time 12
High-performance sodium run with high efficiency and long life of 000 hours
Have been developed and popularized. Where high pressure sodium
The arc tube shape of the lamp is an elongated shape.
Parameter Le / φ_iThe value becomes the type with high lamp input
Has been increased. For example, the specific size of 400W type
The distance between electrodes is 84 mm and the inner diameter of the arc tube is φ_iIs 7.
Le / φ at 65 mm_iThe value is set to 11.0, while 70
0W type is Le134mm and φ_iLe at 9.7 mm
/ Φ_iThe value is set to 13.0. And of the arc tube
Tube wall load we is about 15W / c for each 400W type
m ²And about 13W / cm for 700W type²Set to
There is.

In addition, in the conventional high-watt type quartz arc tube metal halide lamp for general outdoor lighting, basically, a relatively long and narrow light emission is made in contrast to the low-watt type thick and short type for indoor lighting. The tube shape is adopted. Again, the arc tube shape parameter Le / φ _i value increases with increasing lamp watts. For example, 30
Typical Le / φ _i values for 0W, 400W, 700W and 1000W types are set to 2.1, 2.2, 2.5 and 2.7 respectively. Further, the rated life time of the lamp is usually specified to be 9000 hours or more.

As described above, the high pressure discharge lamps can be classified into two types in terms of the shape of the arc tube. One is a so-called long arc lamp, which is a high watt type and elongated type for general outdoor lighting. The other is a low wattage type for indoor lighting in stores, etc., and a lamp for special-purpose lighting such as projection, exposure, and studios. These are so-called short arc type lamps with a comparatively thick and short arc tube shape. is there.

In the former conventional high watt type high pressure sodium lamps and metal halide lamps for general outdoor lighting, the elongated arc tube shape has been adopted because of its high efficiency as a lamp characteristic, usually 9000.
This is because a long life of more than an hour is required. That is,
The life of the high-pressure discharge lamp is mainly influenced by the blackening of the arc tube due to the evaporation and scattering of the electrode material at both ends of the arc tube.
Therefore, even if the lamp input is increased, if the shape is narrower, the influence of the blackening due to the electrode material on the central portion of the arc tube can be avoided and the long life of the lamp can be achieved. In addition, the tube wall load we value of the arc tube of a lamp for general outdoor lighting is usually 23 W / cm ² or less even if an alumina ceramic tube having excellent durability and heat resistance is used.
It is set to the range of 0 ° C or less), which is also 90
This is one of the necessary conditions for obtaining the above long life of 00 hours or more.

[0013]

The present inventor has worked on the development of a high watt type metal halide lamp of 200 W or more using an alumina ceramic tube for general outdoor lighting in response to the demand of the market. Therefore, in order to obtain high lamp efficiency, cerium iodide and sodium iodide were selected as the light emitting substances. As a result, for example, it becomes possible to replace the most powerful 400 W type of the conventional quartz arc tube metal halide lamp with the 300 W type.

In the case where higher efficiency is demanded as described above, when high efficiency metals such as cerium and praseodymium are used, it is necessary to considerably increase the load on the arc tube because these metals have a low vapor pressure. . Therefore, if the airtightness of the shrink-fitted portion is not excellent, that portion may not withstand the vapor pressure during lighting and may burst.

In order to improve the reliability of the shrink-fitted portion,
Inevitably, it is necessary to increase the wall thickness near the shrink-fitted area. Increasing the wall thickness in the vicinity of the shrink-fitted portion causes a large heat loss at that portion, which causes a problem of reduced lamp efficiency.

Further, due to the non-uniform temperature at both ends inside the light emitting portion and the sinking of the light emitting material into the thin tube portion, the light emitting material in the light emitting portion is reduced and the luminous efficiency is lowered, and the pressure resistance of the light emitting tube. There are also problems of decline.

The present invention has been made to solve the above conventional problems, and has sufficient withstand voltage performance during lighting.
The temperature inside both ends of the light emitting part can be made uniform,
An object of the present invention is to provide a metal halide lamp which has a small heat loss, can suppress a decrease in a luminescent substance contributing to light emission, and has high efficiency and a long life.

Further, the present invention has been made to solve such a problem, and provides a metal halide lamp which is capable of suppressing damage to the arc tube during life and the like and has high efficiency and long life. With the goal.

[0019]

In order to achieve the above object, the metal halide lamp of the present invention is provided with a pair of electrodes therein and contains at least one of cerium (Ce) and praseodymium (Pr). Translucency having a light emitting part in which a light emitting substance is enclosed, thin tube parts provided at both ends of the light emitting part, and a power supply body sealed in the thin tube part and connected to the electrode. A ceramic arc tube is provided, wherein the light emitting section is configured such that a ratio of the minimum thickness of the light emitting section to the maximum thickness of the light emitting section is 0.80 or more, and the light emitting section and the thin tube section are provided. And are integrally molded.

With this structure, it is possible to have sufficient withstand voltage performance during lighting and reduce the risk of the arc tube being damaged. Further, since there is no connection part such as a shrink fit part between the light emitting part and the thin tube part, it is excellent in airtightness and it is not necessary to form a part having a large wall thickness. Therefore, heat loss is small, and as a result, the vapor pressure of the luminescent material can be sufficiently increased and the lamp efficiency can be improved.

Further, preferably, both end portions of the light emitting portion have portions whose diameter gradually decreases as they approach the thin tube portion. As a result, the temperature inside the light emitting section becomes uniform, and the lamp efficiency can be improved.

Further, both ends of the light emitting portion may be tapered.

Further, the cross-sectional shape of the both ends of the light emitting portion may be formed by a curved line.

Further, it is preferable that the both ends of the light emitting portion have a substantially hemispherical shape. Accordingly, even when the light emitting tube is lit in a vertically installed state, it is possible to prevent the light emitting material from sinking into the thin tube portion and reducing the amount of the light emitting material in the light emitting portion. Therefore, the lamp efficiency is improved.

Further, preferably, protrusions or grooves may be formed on the inner surfaces of the both ends of the light emitting portion.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIGS. 1 and 2
FIG. 1 is a diagram showing a structure of an arc tube of a metal halide lamp according to a first embodiment of the present invention and a structure of an entire lamp, respectively.

In the arc tube 1, the envelope 2 is made of a semi-transparent polycrystalline alumina ceramic material, and the central part of the tube is made up of a cylindrical light emitting part 3 and thin tube parts 4, 5 at both ends thereof. . The thin tube portions 4 and 5 have a specific resistance value of 5.1 × 10 ^−7.
Ωm Al ₂ O ₃ —Mo system conductive cermet rod-shaped power supply members 6 and 7 are hermetically sealed by ceramic frit 8 whose main component is Dy ₂ O ₃ —Al ₂ O ₃ —SiO ₂ . . The extended electrode rods of the tungsten electrodes 9 and 10 are connected to the discharge-side end portions of the power supply bodies 6 and 7, respectively. In this case, in order to maintain a strong air-tight seal with the thin tube portions 4 and 5 throughout the life of the lamp, the power supply members 6 and 7
Has a thermal expansion coefficient of 6.9 × 10 ^-6 / ° C compared to 8.1 × 10 ^-6 / ° C of the thin tube parts 4 and 5 made of alumina ceramic.
Is set to the value of. Further, the ceramic frit 8 is limited and filled up to the vicinity of the joint portion with the tungsten electrodes 9 and 10 of the thin tube portions 4 and 5 which is a low temperature portion in order to suppress the corrosion by the light emitting substance 11 when the lamp is turned on. There is. Then, in the arc tube 1, cerium iodide (CeI
₃ ) and sodium iodide (NaI), a light-emitting substance 11, mercury as a buffer gas, and about 13 kPa of argon as a rare gas for starting assistance are enclosed.

As the completed lamp 12, as shown in FIG. 2, the arc tube 1 is held inside an outer bulb 13 made of hard glass filled with nitrogen of 60 to 80 kPa, and further equipped with a base 14. It is composed of

The inventor of the present invention firstly proposes a lamp 12 of 300 W type which is a main product having the basic structure shown in FIGS. 1 and 2.
In particular, the two phenomena of "arc tube cracking and discharge arc extinction" that occur when the (CeI ₃ + NaI) -based luminescent material 11 is encapsulated were clarified, and studies were conducted to find means for preventing them.

Specifically, as the parameters that affect the cracking of the arc tube, (i) the shape parameter Le / φ _i value of the arc tube consisting of the tube inner diameter φ _{i at the} tube center and the inter-electrode distance Le, and (ii) inclusion. The composition of the (CeI ₃ + NaI) -based luminescent material 11 is assumed to be two lamp constituent elements, and a test lamp 12 in which these elements are changed was prepared, and the phenomenon of arc tube cracking during aging lighting was examined. Actually, (i) as the arc tube size, the tube inner diameter at the tube center and the distance between the electrodes are φ _i 7.6-
By combining in the range of 20.0 mm and Le 8 to 60 mm, the arc tube shape parameter Le / φ _i value is 0.4 to 8.0.
And (ii) 12 mg of the luminescent substance 11 in which the molar composition ratio NaI / CeI ₃ was changed in a wide range of 2 to 50 as the (CeI ₃ + NaI) composition was encapsulated, and the arc tube 1 was prototyped. Got ready. Then, in the combination of the tube inner diameter φ _i and the inter-electrode distance Le of the above item (i), the tube wall load we of the arc tube was set to be maintained in a relatively low range of 13 to 23 W / cm ² or less. . The lower limit value of we is set in terms of achieving a high lamp efficiency of 117 lm / W or more, which is 30% higher than that of a conventional quartz arc tube lamp, and the upper limit value of we is for general outdoor lighting. It was set in view of achieving a desired lamp life time of 9000 hours or more. The amount of mercury in the tube was regulated and enclosed in a range of 5 to 20 mg / cm ³ per unit volume of the arc tube so as to correspond to an average lamp voltage of 120 V and an average lamp current of 2.6 A during steady lighting.

In the test lamp 12, the arc tube was held in a horizontal position and aging lighting was performed, and during that period, the arc tube was cracked and the discharge arc extinguishing was observed. In addition, lamp characteristics such as efficiency in initial aging and lamp life characteristics due to aging were measured.

From the above test results, first, two lamp constituent elements, that is, the arc tube cracking and discharge arc extinction phenomenon in the test lamp 12, the arc tube shape parameter Le / φ _i value, and the composition of the (CeI ₃ + NaI) -based luminescent material, are shown. A clear correlation was confirmed between and.

That is, the arc tube shape parameter Le / φ _i value is in the range of greater than 1.80 and the molar composition ratio NaI /
Of the 100 test lamps with CeI ₃ set in the range of less than 3.8, arc tube cracking occurred in 24 lamps, while discharge arc extinction occurred in 36 lamps.
In this case, 22 of the 24 lamps where the arc tube was cracked
The discharge arc extinguished with a lamp also occurred before the arc tube cracked. On the other hand, the Le / φ _i value is 0.40 to 1.80.
And the molar composition ratio NaI / CeI ₃ is 3.8 to
With the 80 test lamps set in the range of 50, cracking of the arc tube and extinction of the discharge arc did not occur at all. Here, the fact that the arc tube was cracked and the discharge arc was extinguished in the 22 lamps indicates that the two phenomena were basically due to the same cause. Further, when the aging time at which the two phenomena occurred was examined, it was found that the discharge arc extinction of the 36 lights was 30 to 30 immediately after the initial aging lighting.
It occurred in 0 seconds, while the arc tube crack occurred in 6 of the 24 lamps during the initial aging of 60 minutes.

On the other hand, when the state of the discharge arc of the test lamp 12 is observed, the occurrence of two phenomena is observed Le / φ
_i value is larger than 1.80 and molar composition ratio NaI / Ce
In the lamps in which I ₃ is less than 3.8, that is, CeI ₃ is increased with respect to NaI, (a) the discharge arc region where light is emitted is uniformly narrowed, and (b) discharge is performed. It was confirmed that the arc region had a large curvature toward the upper side of the arc tube. In contrast, the Le / φ _i value, which had not occurred in both phenomena, was 0.40 to 1.80 and the molar composition ratio was Na.
In the lamp in the range where I / CeI ₃ is increased to 3.8 to 50, NaI is increased (a), the discharge arc region is relatively wide in the tube radial direction, and (b) is above the arc tube in the discharge arc region. It was also confirmed that the curvature of was small.

Next, from the measurement of the initial lamp efficiency, when the molar composition ratio NaI / CeI ₃ becomes larger than 10, Na
The above-mentioned yellow spectrum emission mainly increases, and a lamp efficiency higher than 117 lm / W, which is a 30% increase compared with the conventional quartz arc tube lamp, was not achieved. On the other hand, when the molar composition ratio NaI / CeI ₃ is in the range of 3.8 to 10, the green spectral emission of CeI, which has a high relative luminous efficiency, increased, and the target lamp efficiency of 117 lm / W or more was obtained.

From the measurement of the life characteristics, regarding the test lamp 12 in which the Le / φ _i value was set to a small range of 0.40 to less than 0.80, neither arc tube cracking nor discharge arc extinction occurred. Although it was prevented, it was found that the blackening in the vicinity of the electrode at the end of the arc tube due to the aging lighting was severe, and the rated life time of 9000 hours or more applicable to general outdoor lighting could not be achieved at all.

From the above results, the arc tube cracking of the 300 W type (CeI ₃ + NaI) type metal halide lamp using the alumina ceramic tube has a Le / φ _i value of 1.80.
Ce, a larger and rare earth halide material
In the range where I ₃ is increased with respect to NaI, the discharge arc region is narrowed down and is greatly curved to the upper side of the horizontally lit arc tube, which locally raises the temperature of the tube wall above the arc tube. Can be said to be due to. In addition, since the discharge arc extinguishes together with the arc tube cracking, it can be said that basically the discharge arc region is narrowed and curved, and the discharge arc voltage rises excessively. Further, it is generally known that when a luminescent substance is present as molecules in the discharge arc region, the discharge arc extinguishes easily. Especially, in the CeI ₃ sealed lamp of the present invention, the presence of CeI ₃ molecules (spread unique molecules). It can be said that the spectral radiation) contributes to the extinction of the discharge arc.

When a rare earth element such as Ce is enclosed, the average excitation voltage V _e of the energy levels involved in the emission thereof is basically lower than 0.585 times the ionization voltage V _i (that is, V _e <0585 · V _i ), it is known that the discharge arc region is narrowed down. When the discharge arc area is narrowed down, the arc area temperature rises and a large buoyancy is exerted to bend the arc tube to the upper side. At the same time, in the elongated arc tube having a Le / φ _i value of more than 1.80, the bending is promoted to that extent. It Further, the coefficient of thermal expansion of polycrystalline alumina ceramics of 8.1 × 10 ⁻⁶ / ° C. is 5.5 that of conventional quartz.
Since it is larger than × 10 ^-7 / ° C, the mechanical strength of the alumina ceramic tube is comparatively lower than that of conventional quartz, especially against a sudden and local temperature rise due to lighting of the lamp. It can be said that the arc tube cracked. Further, the occurrence rate of cracking of the arc tube is relatively high immediately after lighting for 60 minutes in the initial aging, because the chemical mixing state and the local distribution state of the luminescent material in the arc tube are transient, and as a result, It can be said that the vapor pressure of the CeI ₃ enclosed in was rapidly increased to a higher level, and the curvature of the discharge arc region toward the upper side of the arc tube was increased accordingly.

On the other hand, Le / φ_iSo-called values below 1.80
Thick and short arc tube and molar composition ratio NaI / CeI₃But
No arc tube cracking occurred with 3.8 or more lamps
Is that the discharge arc area is widened by increasing NaI.
It is known that the
The degree of bending in the electric arc region is further reduced, and the pipe inner diameter φ
_iOf arc tube due to bending of discharge arc area due to increase of arc
It can be said that the rise in temperature is also reduced.

In summary, in a 300 W lamp using an alumina ceramic arc tube in which a cerium / sodium iodide (CeI ₃ + NaI) luminescent material is encapsulated, (a) arc tube cracking is peculiar to CeI ₃ inclusion. This is due to the bending of the arc region toward the upper side of the arc tube due to the restriction of the discharge arc region and the low mechanical strength against temperature rise due to the high thermal expansion coefficient of the alumina ceramic tube. CeI in addition to the curvature of the area
It can be said that this is due to the rise in the discharge arc voltage due to the presence of molecules. Then, as a first specific means capable of preventing the above two phenomena, the arc tube shape parameter Le / φ _i value is 1. within the range of the tube wall load we13 to 23 W / cm ² .
It was found that setting the molar composition ratio NaI / CeI ₃ in the range of 80 or less and 3.8 or more was extremely effective. That is, although the arc tube shape of the conventional high-pressure discharge lamp for general outdoor lighting is an elongated shape, in order to obtain a safe (CeI ₃ + NaI) -based metal halide lamp using an alumina ceramic tube, which is the object of the present invention, It is necessary to suppress the tube wall load we to a relatively low range and increase the amount of NaI with a thick and thin shape.

On the other hand, in order to achieve the target lamp efficiency of 117 lm / W or more and the life time of 9000 hours of 30% increase, the molar composition ratio NaI / CeI ₃ is 10 or less and the shape parameter Le / φ _i value is 0. It is necessary to specify in the range of .80 or more.

After all, in order to obtain a safe, highly efficient and long-life 300W type (CeI ₃ + NaI) type metal halide lamp using the alumina ceramic arc tube, which is the object of the present invention, basically, the arc tube shape parameter Le is used. / Φ _i value is 0.80 to 1.80, molar composition ratio NaI / CeI ₃ is 3.8 to 10, and it has been clarified that it may be specified in the range of tube wall load we13 to 23 W / cm ² . .

As an arc tube shape, an elliptical alumina ceramic arc tube as shown in FIG. 3 was used to carry out the same study, and as a result, the tube wall load we of the arc tube was 13 to the same.
As long as the range of 23 W / cm ² is maintained, the above 300 W of FIG.
Similar to the type, the arc tube shape parameter Le / φ _{i, max} value 0.80 to 1.80 (where φ _{i, max} is the tube inner diameter at the center of the arc tube) and the molar composition ratio NaI / CeI ₃ 3.8 to. It was found that the lamps aimed at by the present invention can be obtained by setting the respective ranges of 10.

300 W which is the main product according to the present invention
A typical type of lamp 12 was prepared, the effect of preventing arc tube breakage and discharge arc extinction was confirmed, and characteristics such as life characteristics and lamp efficiency were measured. In this case, the lamp has the basic configuration shown in FIGS. 1 and 2, and the specific configuration of the arc tube 1 is as follows: distance between electrodes Le 23.8 mm, tube inner diameter φ _i 17.6 mm, arc tube shape parameter Le / φ _i 1 .
35 and tube wall load we of 16.8 W / cm ² , respectively, and 12 mg of luminescent material 11 having a molar composition ratio NaI / CeI ₃ of 8 and 53 mg of mercury were enclosed in the tube. As a result, with the structure of the arc tube according to the present invention, neither cracking of the arc tube nor extinction of the discharge arc occurred, and the lamp efficiency was an excellent value of 123 lm / W which exceeded the target value. It was also found that the rated lamp life time could reach 12,500 hours, exceeding the target value of 9000 hours. As for the color rendering of the lamp, the level of the average color rendering index Ra60, which is the lower limit applicable to general outdoor lighting, was obtained. However, each value is an average value of 10 lamps.

As the light emitting substance 11, (CeI ₃ +
Other metal halide substances may be added to contain the NaI) -based substance as a main component and further improve the lamp color rendering properties and life characteristics as long as the above target lamp efficiency is satisfied.

The present inventor has made the above-mentioned 300
200W, 400W for general outdoor lighting other than W type
700W and 1000W type metal halide lamps
As for the 300W type, the arc tube cracks
And discharge arc can be prevented from extinguishing, and the conventional quartz
High efficiency of 30% higher than the light tube lamp and at rated life
Light emitting type that can achieve a long life of 9000 hours or more
Condition parameter Le / φ _iValue (or Le / φ_{i, max}value)
And NaI / CeI₃The range of composition ratio was investigated.

The test lamp 12 of each watt type is shown in FIG.
Alternatively, the lamp 12 has the configuration shown in FIG. 2 by using the arc tube 1 in which the light emitting section 3 and the thin tube sections 4 and 5 having the basic configuration of FIG. 3 are integrally molded. In this case, similarly to the 300 W type test, the combination of the inter-electrode distance Le of the arc tube 1 and the tube inner diameter φ _i is changed according to each type, and the arc tube shape parameter Le / φ _i value (or Le / φ _i value). _{i, max} value)
Was set in a relatively wide range to prepare the test lamp 12. In this case, in order to achieve the target rated life time of 9000 hours or more, the above-mentioned 300 is set as the pipe wall load we.
It was defined in the range of 13 to 23 W / cm ² according to the W type. Further, as the light emitting substance 11, NaI / CeI ₃ of cerium / sodium iodide is used as in the above-mentioned 300 W type.
Those with different composition ratios were enclosed.

With respect to each of the watt type test lamps 12, the arc tube cracking and the discharge arc extinguishing phenomenon under the aging lighting similar to the 300 W type were observed, and various characteristics such as lamp efficiency and life time were measured.

From the above observation and measurement results, it was possible to prevent arc tube breakage and discharge arc extinction in each watt type test lamp 12, and also to improve efficiency and rated life by 30% as compared with conventional quartz arc tube lamps. In order to achieve a long life of 9000 hours or more, (i) arc tube load w
In the range of 13 to 23 W / cm ² , the arc tube shape parameter Le / φ _i value (or Le / φ _{i, max} value) is set to lamp watts 200 W, 400 W, 700 W and 1000 W.
Against 0.75 to 1.70 and 0.85 to 1.9, respectively.
0, 1.00 to 2.00 and 1.15 to 2.10 (corresponding to the shaded area in FIG. 4 for other lamp watts), and (ii) a luminescent material (CeI ₃ + NaI). It has been clarified that the molar composition ratio NaI / CeI ₃ of) may be defined in the range of 3.8 to 10. As can be seen from this, even if the lamp wattage rises to 1000 W, the arc tube shape parameter Le / φ _i value of (i) above needs to be suppressed to a range of 2.10 or less without being greatly increased.

After all, (CeI ₃ + Na) for general outdoor lighting
It can be said that in the alumina ceramic arc tube metal halide lamp using the I) type luminescent material, the arc tube shape becomes thick and short through the lamp watts 200W to 1000W.

As described above, the high wattage type (CeI ₃₎ for general outdoor lighting using the alumina ceramic arc tube is used.
+ NaI) -based metal halide lamp, the molar composition ratio NaI as the main component as shown in the above embodiment.
/ CeI ₃ is filled with a luminescent substance set in the range of 3.8 to 10, and the tube wall load we of the arc tube is 13 to 23 W /
By setting the arc tube shape parameter Le / φ _i value in cm ² in the range of 0.80 to 1.80 for the main product type 300 W type, for example, the desired safe, highly efficient and long life metal halide can be obtained. You get a lamp.

In addition, since the light emitting portion and the thin tube portion are integrally molded, there is no shrink fit portion unlike the conventional metal halide lamp. Therefore, the light emitting portion is not provided with a portion having a large thickness, so that heat loss can be reduced, the vapor pressure of cerium can be increased, and the lamp efficiency can be further improved.

Even if praseodymium is enclosed instead of cerium, the same effect as above can be obtained.

(Second Embodiment) FIG. 5 is a diagram showing the structure of the arc tube 1 of the metal halide lamp according to the second embodiment of the present invention.

The envelope 2 including the light emitting portion 3 and the thin tube portions 4 and 5.
Consists of a translucent polycrystalline alumina ceramic material. The light emitting portion 3 has a cylindrical central portion, and both end portions thereof have a substantially conical shape and are tapered. The thin tube portions 4 and 5 are formed at both ends of the light emitting portion 3. Embodiment 2
Since the light emitting part 3 and the thin tube parts 4 and 5 are integrally molded, there is no shrink fit part. Therefore, unlike the conventional arc tube 115 shown in FIG. 8, it is not necessary to make a part where the wall thickness is large in the light emitting part 3 (for example, around the connection part between the light emitting part and the thin tube part). Therefore, the heat loss in the light emitting unit 3 is small, and the vapor pressure of the light emitting substance 11 can be sufficiently increased.
Lamp efficiency is improved.

The thin tube portions 4 and 5 have a specific resistance value of 5.1 × 10 5.
^-7 Ωm of Al ₂ O ₃ -Mo system conductive cermet rod-shaped power supply bodies 6 and 7 are hermetically sealed by ceramic frit 8 mainly composed of Dy ₂ O ₃ -Al ₂ O ₃ -SiO _2. ing.

Tangs are provided at the discharge-side tips of the power supply members 6 and 7.
The extended electrode rods of the ten electrodes 9 and 10 are joined respectively.
Is held. In this case, the thin tube part
In order to maintain a strong airtight seal with the power supply 4, 5, the power supply 6, 7,
The coefficient of thermal expansion of
8.1 × 10 of pipe parts 4 and 5^-6/ ° C for 6.9 x 10 ^-6
It is set to the value of / ° C. Also a ceramic frit
8 suppresses erosion by the light emitting substance 11 when the lamp is turned on.
In order to reduce the temperature
It is limited and filled up to the vicinity of the junction with the poles 9 and 10.
Then, in the arc tube 1, for example, cerium iodide (C
eI₃) And sodium iodide (NaI)
Light substance 11, mercury as a buffer gas, and a rare gas for starting assistance
About 13 kPa of argon is enclosed as a gas. Na
The molar composition ratio NaI / CeI of the luminescent material 11₃Is 6.
It is 0.

In the completed lamp 12, as shown in FIG. 2, the arc tube 1 according to the second embodiment has nitrogen of 60 to 80 k.
Outer bulb valve 1 made of hard glass in which Pa is enclosed
It is held inside 3 and is further equipped with a base 14.

Next, the results of evaluating the characteristics of the metal halide lamp of the second embodiment and the conventional metal halide lamp based on the measured values will be described.

The conventional metal halide lamp has the same basic structure as the lamp 12 shown in FIG.
In place of the arc tube 1 in, the conventional arc tube 115 configured by shrink fitting shown in FIG. 8 is used. Cerium iodide and sodium iodide (CeI ₃ + NaI) -based light-emitting substances are enclosed in the light-emitting portions _{3 and} 116, respectively.
It was a 0W type. Ten samples were prepared for each metal halide lamp, and the initial efficiency was compared by the average value of the measured values.

As a result, the initial efficiency of the conventional metal halide lamp was 110 lm / W, whereas the initial efficiency of the metal halide lamp of Embodiment 2 was 116 lm.
/ W, which means that the lamp efficiency is higher in the second embodiment.

As described above, according to the metal halide lamp of the second embodiment, the envelope 2 of the arc tube 1 has the light emitting portion 3
And the thin tube portion 3 are integrally molded. Thereby, since it is excellent in airtightness, it is not necessary to form a part having a large wall thickness locally, and heat loss is small. Therefore, the vapor pressure of cerium can be sufficiently increased to improve the lamp efficiency.

(Third Embodiment) FIG. 6 is a sectional view showing a structure of an arc tube of a metal halide lamp according to a third embodiment of the present invention. The basic structure of the arc tube of the third embodiment is the same as that of the arc tube of the second embodiment, and is different in that
The point is that both ends of the light emitting portion are substantially hemispherical, not conical.

As shown in FIG. 6, the light emitting section 3 and the thin tube section 4,
5 is integrally molded, and both ends of the light emitting portion 3 are substantially hemispherical. Therefore, during lighting, the temperatures of the inner surfaces of both ends are further equalized, and even cerium, for example, having a low vapor pressure, is surely evaporated and contributes to light emission, and the light emission efficiency is improved.

Further, in the arc tube 1 of the second embodiment, when the pair of tungsten electrodes 9 and 10 are lit in a state of being arranged side by side in the vertical direction, the liquid luminous substance 1
1 may sink into the gap between the narrow tube portions 5 below, and the luminescent substance 11 in the light emitting portion 3 may decrease. As a result, there is an inconvenience that characteristics such as color temperature change remarkably. However, in the arc tube 1 according to the third embodiment, since both ends of the light emitting unit 3 are substantially hemispherical, the liquid luminescent material 11 is hard to flow along the inner surfaces of both ends of the light emitting unit 3 and accumulates on the inner surface. Cheap. Therefore, even when the pair of tungsten electrodes 9 and 10 are turned on in a state where they are arranged side by side in the vertical direction, the liquid luminescent substance 11 is unlikely to sink into the gap of the thin tube portion 5 below. Therefore, the light emitting unit 3
The amount of the luminescent material 11 in the inside does not decrease, and the characteristic changes such as color temperature are small.

Next, the results of measuring the initial efficiency of the metal halide lamp of the third embodiment will be shown. The basic structure of the metal halide lamp is the lamp 12 shown in FIG.
In the same manner as above, the arc tube 1 shown in FIG. 6 was used. In addition, the other structure is the same 300 W type metal halide lamp as the actually measured example in the second embodiment, in which cerium iodide and sodium iodide (CeI ₃ + NaI) -based luminescent material are enclosed. Ten metal halide lamps were prepared, and the average value of the measured values was calculated.

As a result, it was found that the initial efficiency was 120 lm / W, which was higher than the initial efficiency (116 lm / W) of the metal halide lamp of the second embodiment described above.

Further, the characteristic change of the color temperature during life could be suppressed. Specifically, in the second embodiment, the initial color temperature was 4200K and Ra71, but 600
After a life of 0 hours, the characteristics were significantly changed to 4600K and Ra67. In comparison with this, in the third embodiment, 6
No major change in properties was observed after 000 hours of life.

Further, in FIG. 6, the lamp efficiency and the arc tube damage during life when the wall thickness t1 of the central portion of the light emitting section 3 and the wall thickness t2 of the light emitting section 3 near the thin tube portions 4 and 5 are changed respectively. The probability was measured. As in the above, 10 samples were prepared for each sample, and the average value thereof was used as the measured value. Also, the probability of damage to the arc tube during life was measured up to 6000 hours. The results are shown in Table 1.

[0070]

[Table 1]

From Table 1, the thickness t1 of the central portion of the light emitting portion 3
When the wall thickness t2 in the vicinity of the thin tube portions 4 and 5 of the light emitting portion 3 is changed with the value of 1.0 kept constant at 1.0 mm, the wall thickness t2 is 0.7 mm
In the following cases, breakage of the arc tube 1 was confirmed during life.
This is because the thickness of the boundary portion between the light emitting portion 3 and the thin tube portions 4 and 5 is thin, and the portion thereof becomes brittle due to the reaction of the liquid light emitting substance 11 existing in the vicinity thereof, and the pressure resistance performance deteriorates.

Further, it was confirmed that the lamp efficiency greatly decreased when the wall thickness t2 was 1.3 mm or more.
This is because the thickness of the boundary portion between the light emitting portion 3 and the thin tube portions 4 and 5 is large, so that the temperature of the light emitting tube at that portion does not rise, and the light emitting substance 11 having a low vapor pressure does not evaporate sufficiently and emits light. This is because they could not contribute.

Next, when the wall thickness t2 in the vicinity of the thin tube portions 4 and 5 of the light emitting portion 3 is fixed to 1.0 mm and the wall thickness t1 of the central portion of the light emitting portion 3 is changed, the wall thickness t1 becomes 0. When it was less than 0.7 mm, it was confirmed that the arc tube 1 was damaged during life. The main cause is the decrease in pressure resistance performance due to the thin thickness of the light emitting portion 3.

Further, it was confirmed that the lamp efficiency is greatly reduced when the wall thickness t1 is 1.3 mm or more. The main reason for this is that the light emitting portion 3 has a large thickness and thus has a low transmittance.

From the above results, by setting the ratio of the minimum thickness of the light emitting portion 3 to the maximum thickness of the light emitting portion 3 to 0.80 or more, heat loss can be further reduced and high efficiency can be realized. It was also found that it is possible to suppress damage to the arc tube during life.

In the third embodiment, the portions corresponding to the maximum thickness and the minimum thickness of the light emitting portion 3 are the central portion of the light emitting portion 3 and the vicinity of the thin tube portion 4, but any portion of the light emitting portion 3 as a whole may be used. The same effect is recognized even if the location is selected.

The molar composition ratio NaI /
CeI ₃ was set to 6.0, but a range of 3.8 to 10 is a preferable value. In addition to NaI, dysprosium (Dy), thulium (Tm), holmium (Ho), thallium (Tl), or the like may be added as the light-emitting substance 11 as appropriate depending on desired lamp characteristics.

Further, even when praseodymium was enclosed instead of cerium, the same effect as above was observed. In that case, the molar composition ratio NaI / PrI ₃ is 4.5 to 12
Is preferred.

As described above, according to the metal halide lamp of the third embodiment of the present invention, since both ends of the light emitting portion 3 are formed in a hemispherical shape, there is a vertical difference between the tungsten electrodes 9 and 10 of the arc tube 1. Even if it is used as it is generated, the liquid luminescent substance does not sink into the thin tube portions 4 and 5,
Since it does not decrease, it has an effect that the luminous efficiency does not decrease.

The shape of both ends of the light emitting portion 3 may not be a hemispherical shape but may be a curved cross section.
It suffices if it is difficult for the liquid luminescent substance 11 to flow into the thin tube portions 4 and 5.

Further, as shown in FIG. 7, the projection 15 may be provided so as to go around the inside of both ends of the light emitting section 3. With such a configuration, it is possible to prevent the liquid luminescent substance 11 from flowing into the thin tube portions 4 and 5. Further, instead of the protrusion 15, a groove may be used, and it is possible to prevent the liquid luminescent substance 11 from accumulating in the groove and flowing into the thin tube portions 4 and 5.

[0082]

According to the present invention, the temperature inside both ends of the light emitting portion can be made uniform, the heat loss is small, and the light emitting material is not reduced, so that the vapor pressure of the light emitting material is sufficiently high. In addition, it has sufficient withstand voltage performance during lighting. Thereby, a highly efficient and long-life metal halide lamp can be obtained.

Further, according to the present invention, it is possible to provide a metal halide lamp which is capable of suppressing damage to the arc tube during life and the like, and which has high efficiency and long life.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of an arc tube of a metal halide lamp according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the overall structure of a metal halide lamp of the present invention.

FIG. 3 is a sectional view showing a configuration of another arc tube of the metal halide lamp according to the first exemplary embodiment of the present invention.

FIG. 4 is a diagram showing a range of arc tube shape parameter Le / φ _i values for a lamp watt defined by the first embodiment of the present invention.

FIG. 5 is a sectional view showing a structure of an arc tube of a metal halide lamp according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing a structure of an arc tube of a metal halide lamp according to a third embodiment of the present invention.

FIG. 7 is a sectional view showing the configuration of another arc tube of the metal halide lamp according to the third embodiment of the present invention.

FIG. 8 is a sectional view showing a structure of an arc tube of a low watt type alumina ceramic tube metal halide lamp according to a conventional technique.

FIG. 9 is a cross-sectional view showing a structure of an arc tube of a short arc type alumina ceramic tube metal halide lamp according to a conventional technique.

[Explanation of symbols]

1 arc tube 2 envelope 3 light emitting part 4,5 thin tube section 6,7 Feeder 8 ceramic frit 9,10 Tungsten electrode 11 Luminescent substances 12 lamps 13 Outer pipe valve 14 mouthpiece 15 protrusions

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiharu Nishiura             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Masanori Higashi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hiroshi Enoki             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5C015 QQ18 QQ19                 5C039 HH03                 5C043 AA02 AA07 CC03 CD05 DD03                       EA07

Claims (6)

[Claims] 1. A light emitting part having a pair of electrodes provided therein, and a light emitting material containing at least one of cerium (Ce) and praseodymium (Pr), and a light emitting part provided at both ends of the light emitting part. A light-transmitting ceramic light-emitting tube having a thin tube portion and a power supply body sealed in the thin tube portion and connected to the electrode, wherein the light-emitting portion has a maximum thickness of the light-emitting portion. A metal halide lamp characterized in that the ratio of the minimum wall thickness of the light emitting portion to the thickness is 0.80 or more, and the light emitting portion and the thin tube portion are integrally molded. 2. The metal halide lamp according to claim 1, wherein both ends of the light emitting portion have portions whose diameter gradually decreases toward the thin tube portion. 3. The metal halide lamp according to claim 2, wherein the both ends of the light emitting portion are tapered. 4. The cross-sectional shape of the both ends of the light emitting portion is
The metal halide lamp according to claim 2, wherein the metal halide lamp is formed of a curved line. 5. The metal halide lamp according to claim 4, wherein the both end portions of the light emitting portion have a substantially hemispherical shape. 6. The metal halide lamp according to claim 2, wherein protrusions or grooves are formed on inner surfaces of the both ends of the light emitting unit.