JPH07220685A - Reflection discharge lamp and lighting device thereof - Google Patents

Abstract

PURPOSE:To prevent leakage of an arc tube or blackening in its early stages by restraining a temperature rise in a sealing part of the arc tube. CONSTITUTION:An arc tube 1 where a pair of electrodes 4 are arranged in a bulb 2 and a sealing part 3 is formed on one side end part of this bulb and a reflection envelope 10 where a reflecting surface 25 is formed on an inside of a reflector 12 housing the arc tube 1 and having a focus F, and a front surface opening part is blocked up by glass 15, are provided. In this reflection type discharge lamp, in the arc tube 1, one side sealing part 3 is arranged in a position of the focus F of the reflecting type envelope 10. Since the sealing part 3 of the light emitting tube 1 is arranged on the focus of the reflecting envelope, the sealing part is situated in a place separated from a heat gathering place in the envelope, so that a temperature rise in the sealing part can be retrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type discharge lamp in which a small size discharge lamp is housed in a reflection type envelope and a lighting device therefor.

[0002]

2. Description of the Related Art Recently, high-pressure metal vapor discharge lamps have been downsized and reduced in wattage, and their applications have been expanded.
For example, as a lighting fixture for stores, the arc tube of a metal halide lamp is downsized and reduced in wattage, the arc tube is housed in a reflective envelope, and the light emitted from the arc tube is reflected by the reflective envelope. Reflective discharge lamps have been developed to illuminate the front of the product, and such reflective discharge lamps are used to illuminate products that are installed and displayed on the ceiling of a store, and are used as, for example, downlights. To be

When a metal halide lamp is used as a light source of such a reflection type discharge lamp, the metal halide lamp originally has high luminous efficiency, low color temperature and excellent color rendering property. When used for various store lighting, there are advantages such as excellent color reproducibility of products.

A conventional structure of such a reflection type discharge lamp will be described with reference to FIG. In FIG. 5, reference numeral 1 denotes an arc tube of a small-sized metal halide lamp used as a light source, which has a crushed sealing part 3 formed at one end of a bulb 2 made of quartz glass. A pair of electrodes 4 and 4 are sealed in the sealing portion 3. The pair of electrodes 4, 4 are opposed to each other in the arc tube 1 with a predetermined distance between the electrodes. The electrodes 4 and 4 are connected to metal foil conductors 7 and 7 made of molybdenum that are sealed in the crushing and sealing portion 3, and these metal foil conductors 7 and 7 are external lead wires 8 and 7.
8 is connected. The external lead wires 8 and 8 are led out from the end surface of the crushable sealing portion 3.

Such an arc tube 2 is housed in a reflection type envelope 10. The reflective envelope 10 includes a reflector 12 and
It is composed of a front glass 15 that hermetically closes the front opening of the reflector 12, and a base 18 attached to the back surface of the reflector 12.

The reflector 12 is made of, for example, hard glass and forms a rotation curve having a focal point F, for example, a paraboloid of rotation, and the inner surface thereof is a reflection film 25 made of an aluminum vapor deposition film or the like.
Are formed. A front glass 15 is airtightly joined to the front opening of the reflector 12 to keep the inside of the reflective envelope 10 in an airtight space. The inside of the reflective envelope 10 is maintained in a vacuum atmosphere.

In the conventional case, as shown in the figure, the light emission center O formed between the pair of electrodes 4 and 4 is positioned at or near the focal point F of the reflective envelope 10. The arc tube 1 is housed in a reflective envelope 10. In FIG. 5, members having the same structures as those of the embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted.

[0008]

However, in the case of such a conventional structure, the light emission center O of the arc tube 1 is arranged at or near the focal point F of the reflection type envelope 10, and for this reason. The one-side sealing portion 3 of the arc tube 1 was installed at the inner part of the reflector 12, that is, at a position near the closing wall 23. Since such a position of the sealing portion 3 is a recessed position of the reflector 12, heat is likely to be accumulated therein, and heat reflected by the reflecting surface formed on the inner surface or the outer surface of the concave portion 22 is likely to be collected, so that the sealing is performed. The temperature of the stopper 3 rises.

In the case of a metal vapor discharge lamp, unless the temperature of the arc tube is raised to some extent, the enclosed metal may not be vaporized sufficiently and the vapor pressure may be insufficient. Therefore, the device for keeping the temperature of the sealing portion 3 high to some extent There are some that have been, but conversely the sealing part 3
If the temperature of the arc tube becomes too high, the temperature of the entire arc tube becomes too high, the diffusion of the encapsulated metal, for example, sodium Na, becomes large and the sodium is lost, or the metal foil conductors 7, 7 are oxidized. However, there are problems such as leakage from the sealed portions of the metal foil conductors 7 and blackening due to scattering of the electrode material.

The present invention has been made in view of the above circumstances. An object of the present invention is to prevent the temperature rise of the sealing portion of the arc tube and prevent leakage and early blackening. An object of the present invention is to provide a discharge lamp and its lighting device.

[0011]

According to a first aspect of the invention, a bulb is provided with a pair of electrodes in the bulb and a sealing portion is formed at one end of the bulb, and the bulb is housed.
In a reflection type discharge lamp comprising a reflection type envelope having a reflection surface formed on an inner surface of a reflector having a focal point and having a front opening closed with glass, the arc tube has the one side sealing portion. It is characterized in that it is installed at the position of the focal point of the reflective envelope.

The invention of claim 2 is characterized in that the arc tube is filled with a metal halide containing at least sodium. The invention of claim 3 is characterized in that the front glass of the reflection type envelope is provided with a light control portion for controlling the distribution of light traveling forward.

According to a fourth aspect of the present invention, the light control section is a diffusion section for diffusing forward light.
According to a fifth aspect of the present invention, there is provided the reflection type discharge lamp according to any one of the first to fourth aspects, and a lighting circuit for lighting the discharge lamp.

[0014]

According to the invention of claim 1, since the sealing portion of the arc tube is arranged at the focal position of the reflection type envelope, the position of the sealing portion is removed from the back of the reflection type envelope in which heat is accumulated. In addition to being set to the open position, the heat is reflected from the place where the heat reflected by the reflecting surface is gathered, so that the excessive temperature rise of the sealing portion can be suppressed.

According to the second aspect of the present invention, in the case of an arc tube in which a metal halide containing sodium as a luminescent metal is sealed, in particular, the temperature rise of the sealing portion is suppressed, so that the escape of sodium is reduced. Will be done.

According to the third aspect of the present invention, by disposing the sealing portion of the arc tube at the focus position of the reflection type envelope, the light emission center of the arc tube is deviated from the focus position. Although the light distribution of the irradiation changes, the change of the light distribution can be corrected by the light control unit provided on the front glass of the reflection type envelope.

According to the fourth aspect of the invention, since the light distribution section is the diffusion section, a predetermined light distribution characteristic can be obtained. According to the invention of claim 5, it is possible to obtain a lighting device having excellent life characteristics.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on a first embodiment applied to a downlight type lighting device used for shop lighting or the like shown in FIGS. FIG. 1 is a sectional view showing the whole of a reflection type discharge lamp, and FIG. 2 is an enlarged sectional view showing an arc tube thereof. In FIG. 1, reference numeral 1 shows a small arc tube having a single-sealed structure used as a light source. This arc tube 1 has a crushing seal portion 3 formed at one end of a bulb 2 made of quartz glass. The light emitting portion of the bulb 2 is, for example, the rated input 1
In the case of 50 W, as shown in FIG. 2, the outer diameter D1 in one direction is approximately 17.2 mm, and the outer diameter D2 in the other direction is approximately spherical, and the internal volume is approximately 1.1 cc. Has been formed. Further, the sealing portion 3 is formed by crushing and has a flat shape, and in the case of the above-mentioned arc tube having a rated input of 150 W, the width M is approximately 18.4 mm and the length L is approximately 12.0.
It is formed to about mm.

The bulb 2 has a light-emitting portion provided with a pair of electrodes 4,
4 are arranged to face each other. These electrodes 4, 4
Is constructed by winding electrode coils 6, 6 made of tungsten wire around the tips of electrode shafts 5, 5 made of tungsten, respectively. The pair of electrode coils 6, 6 are arranged in the arc tube 2 between predetermined electrodes. Opposed at a distance of g. In the case of the arc tube having the rated input of 150 W, the inter-electrode distance L is formed to be about 6.2 mm.

The electrode shafts 5 and 5 are connected to metal foil conductors 7 and 7 made of molybdenum, which are sealed in the crushing and sealing portion 3, and external leads made of molybdenum are attached to the metal foil conductors 7 and 7. The lines 8 and 8 are connected. The external lead wires 8 and 8 are led out from the end surface of the crushable sealing portion 3.

In such an arc tube 2, a predetermined amount of Sn-In-Tl-Na iodide or bromide is filled as a light emitting metal, and mercury is filled as a buffer metal and argon gas is filled as a rare gas. Has been done. In the case of the above-mentioned rated input 150 W arc tube, tin Sn is 4.8 μmo
I, indium In is 3.5 μmol, thallium Tl is 2.5 μmol and sodium Na is 2.8 μmol, and iodine I or / and a halide of bromine Br are enclosed.

The single-sealed arc tube 1 having such a structure is housed in the reflective envelope 10. Reflective envelope 10
Is composed of a reflector 12, a front glass 15 that hermetically closes the front opening of the reflector 12, and a base 18 attached to the back surface of the reflector 12.

The reflector 12 is made of, for example, hard glass,
A main reflecting portion 21 having a focal point F, which is composed of a rotation curve formed by forming an outer diameter of the front opening portion to 123 mm, for example, a paraboloid of rotation.
And another rotation curve connected to the main reflection portion 21, for example, an auxiliary reflection portion 22 formed of a paraboloid of revolution, and the inner portion of the auxiliary reflection portion 22 is closed by a closing wall 23.
The inner surfaces of the main reflection portion 21 and the auxiliary reflection portion 22 are each formed by a reflection film made of an aluminum vapor deposition film or the like to form a reflection surface 2.
5 and 22a are formed. The auxiliary reflector 2
The outer surface of 2 is covered with a metal cover 28.

A front glass 15 is attached to the front opening of the reflector 12. The front glass 15 is made of hard glass or neodymium glass containing neodymium oxide, and transmits the light emitted from the arc tube 1 and the light reflected by the reflecting surfaces 25 and 22a forward. The front glass 15 is airtightly joined to the front opening of the reflector 12 by using welding or an adhesive, and thus the inside of the reflective envelope 10 forms an airtight space. Since the arc tube 1 is housed in such an airtight space, the reflection type envelope 10 has the same function of protecting the arc tube as the outer tube of the conventional double tube discharge lamp. The inside of the reflective envelope 10 is maintained in a vacuum atmosphere. The inside of the reflective envelope 10 may be kept in an atmosphere of an inert gas such as nitrogen.

Support wires 26, 26 also serving as a pair of conductive wires are hermetically penetrated through the closed wall 23 of the reflector 12. These support wires 26, 26 are made of nickel Ni, iron Fe, stainless steel, etc., and the outer lead wires 8, 8 of the arc tube 1 are respectively joined to the inner ends extending inside the reflector 12. There is. Therefore, the arc tube 1 is mechanically supported by the support wires 26, 26 and is electrically connected thereto.

In the arc tube supporting structure as described above, the collapsible sealing portion 3 formed at one end of the arc tube 1 coincides with or approaches the focal position F of the main reflecting portion 21 of the reflective envelope 10. As a result, the emission center O formed between the electrodes 4 and 4 is displaced from the position of the focal point F to the front side.

When the arc tube 1 is housed in the reflection type envelope 10 with the sealing portion 3 located at the focal point F, the luminous center O of the arc tube 1 is more than the focal point F in this embodiment. Is also deviated (off-center) to the front side, so that the light emitted from the arc tube 1 tends to spread when reflected by the reflecting surface 25.

In order to correct such a light distribution, a light control section 16 is formed on the inner surface or outer surface of the front glass 15. In the case of the present embodiment, the light control unit 16 is the front glass 1
5 is a light diffusing portion formed in the center portion of the front glass 15. The light diffusing portion is formed by, for example, frosting the outer surface of the front glass 15 to form a satin surface, forming an uneven surface, or the front glass 1
Attach a separate light diffusion plate to 5, or attach a light diffusion tape, or apply a light diffusion paint,
This can be implemented by means such as forming a light diffusion film made of a metal oxide to form a light diffusion layer.

A screw-type base 18 is joined to the rear end of the reflection type envelope 10. The base 18 is provided with a base shell 18a and an eyelet-shaped external terminal 18b formed at its end. The support wires 26, 2
Reference numeral 6 is connected to the base shell 18a and the external terminal 18b through connecting wires 27, 27.

The reflection type discharge lamp having such a structure is connected to a power source 31 via a lighting circuit 30 such as a ballast. That is, the shell 18a and the external terminal 18b of the base 18 are connected to a lighting circuit 30 such as a ballast through a socket (not shown), and the lighting circuit 30 is connected to a commercial power supply 31. Therefore, the reflective discharge lamp and the lighting circuit 30 form a lighting device.

The operation of the reflection type discharge lamp having such a structure, that is, the downlight illumination device will be described. When the reflective discharge lamp is connected to the commercial power supply 31 through the lighting circuit 30, a voltage is applied between the electrodes 4 and 4, arc discharge is generated between the electrodes 4 and 4, and the arc tube 1 is lit. In the arc tube 1, the arc center between the electrodes 4 and 4 becomes the light emission center O, and therefore light is emitted from this light emission center O. Part of the light emitted from the arc tube 1 is directly on the front glass 15
And the rest is reflected by the reflection film 25 formed on the inner surface of the reflector 12 toward the front glass 15, and passes through the front glass 15 to irradiate the front (lower side).

In the present embodiment, since the collapsed sealing portion 3 of the arc tube 1 is installed at the focus position F of the main reflection portion 21 of the reflective envelope 10, the position of the sealing portion 3 of the arc tube 1 is 5 has moved to the front side as compared with the case of the conventional case shown in FIG. 5, and thus is located away from the closing wall 23 of the reflector 12. For this reason, in the case of downward lighting or the like, the reflector 12 is separated from the inside of the reflector 12 where heat is easily accumulated due to convection, and the temperature rise of the sealing portion 3 of the arc tube 1 is reduced. Further, since the sealing portion 3 of the arc tube 1 is located away from the focus position of the reflecting surface 22a of the auxiliary reflecting portion 22, the heat reflected by the reflecting surface 22a is prevented from collecting in the sealing portion 3. Therefore, the temperature rise of the sealing portion 3 is prevented.

Further, the main reflection portion 21 composed of a paraboloid of revolution.
On the reflecting surface 25 of the
When reflected by, there is a property of being reflected as light parallel to the optical axis. On the contrary, when the light parallel to the optical axis is reflected by the reflecting surface 25, it returns to the focal position F.
In the present embodiment, since the emission center O of the discharge lamp 1 is located at a position deviated from the focus position F, the amount of light that is parallel inside the reflective envelope 10 is small, and therefore the light passing through the focus position F is Small quantity. For this reason, the rate at which the heat (infrared rays) emitted from the arc tube 1 returns to the focal position F is small. Therefore,
When the sealing portion 3 of the arc tube 1 is arranged at the focus position F, the rate of heating the sealing portion 3 by infrared rays decreases, and the sealing portion 3
The temperature rise can be reduced.

Therefore, it is possible to prevent oxidation of the metal foil conductors 7, 7 sealed in the sealing portion 3 and foil breakage due to this, and also to prevent thermal expansion difference between quartz and the metal foil conductors 7, 7. It is possible to prevent a leak from occurring.

Further, since the temperature rise of the sealing portion 3 is suppressed, the temperature rise of the entire valve 2 is also suppressed, and when sodium Na is enclosed, the escape of sodium Na is prevented. Become. Therefore, the change of the light color is small, and the luminous efficiency and the color rendering can be maintained at a high level for a long period of time. As a result, the life characteristics of the reflective discharge lamp are improved.

By the way, in the case of the above construction, since the sealing portion 3 of the arc tube 1 is arranged at the focal position F, the arc tube 1
The light emission center O of 8 is off-centered to the front side with respect to the focal position F, so that the light emitted from the arc tube 1 tends to spread when reflected by the reflecting surface 25.

That is, in the case of the conventional structure shown in FIG. 5, the emission center O of the arc tube 1 substantially coincides with the focus position F,
The light distribution characteristics in this case were as shown in FIG. The same discharge lamp 1 and reflective envelope 10 as the conventional one
As shown in FIG. 1, when the sealing portion 3 of the arc tube 1 is placed at the focal position F and its emission center O is set to 15 mm off-center on the front side of the focal position F, as shown in FIG. The light distribution is as shown by the broken line in FIG. This is because the light emission center O is off-centered to the front side of the focus position F, so that the light reflected by the reflecting surface 25 spreads. In order to correct the light distribution of such a broken line, in this embodiment, a light control section 16 is formed in the center of the front glass 15. The light control section 16 of this embodiment is a light diffusion section, and if the light diffusion section 16 is formed at the center of the front glass 15, the light control section shown in FIG.
It is possible to obtain the light distribution indicated by the solid line in FIG.

Therefore, the deviation of the light distribution due to the emission center O being off-centered from the focus position F causes the light diffusion portion 16
Can be modified by The light distribution shown by the solid line in FIG. 3B has a wider light distribution characteristic than the conventional light distribution shown in FIG. 3A. Since there is a tendency that a wider range of light is desired than the spot beam light, the spread beam light is suitable.

When the same spot beam light as that in the conventional case is desired, the light control portion 16 formed in the central portion of the front glass 15 is used.
The desired light distribution characteristic can be obtained by using a light refraction portion or a light condensing portion.

Table 1 below shows the results of experiments conducted on the reflection type discharge lamp having the structure of the first embodiment. The experiment was conducted using a reflection type discharge lamp with a rated input of 150 W, and the positions a to e in the table indicate the position of the focus F as a in FIG.
~ The case of being placed at point e is shown. In addition, 2 trials for each prototype
The average value and% when tested by 0 are shown.

[0041]

[Table 1]

As is clear from Table 1, in the case of the present embodiment, since the sealing portion 3 of the arc tube 1 is installed at the focal point F position,
There is little change in light color after lighting for 6000 hours, which is considered to be due to less loss of sodium Na. Also, 60
Even when the lamp was turned on for 00 hours, no leak was observed from the sealing portion 3, and it is considered that the temperature rise of the sealing portion 3 was suppressed. However, in this case, since the light distribution changes significantly, it is necessary to improve the light distribution. For this reason, the light control portion 16 having a light diffusing action is formed in the central portion of the front glass 15. In this way, the light distribution can be modified, as can be seen from FIG. In Table 1, "improvement required" means that the light distribution needs to be corrected by forming the light control unit.

A lighting circuit 30 is provided for the reflection type discharge lamp as described above.
The lighting device configured to be connected to can effectively utilize the life characteristics of the discharge lamp, and the life of the lighting device is improved. FIG. 4 shows a second embodiment of the present invention, and the difference from the structure of FIG. 1 is that the mounting attitude of the arc tube 1 is reversed. That is, in the case of FIG. 1, an example in which the arc tube 1 is attached in a posture in which the sealing portion 3 faces upward and the sealing portion 3 is positioned at the focal position F of the reflection type envelope 10 is shown. ,
The structure of FIG. 4 is an example in which the sealing portion 3 of the arc tube 1 is attached to the support wires 26, 26 in a downward posture, and the sealing portion 3 is positioned at the focal position F of the reflective envelope 10. Therefore, in this case, the light emitting portion faces upward, and the light emission center O is off-centered to the back side of the focus position F.

Also in this case, since the sealing portion 3 is installed at the focal position F, the temperature rise of the sealing portion 3 is suppressed. And
In this case, the emission center O is off-centered to the rear side of the focal point F, so that the light distribution can be corrected by forming the light control section 16 in the peripheral portion of the front glass 15.

The light control unit 16 shown in FIGS. 1 and 4 is used.
Is not limited to the light-blocking part that performs a diffusing action, but in short, it controls the direction of the light passing through the front glass 15, and therefore various functions such as refraction, reflection, and light blocking are possible, and the light-blocking is possible. The position where the portion 16 is provided is not limited to the central portion or the peripheral portion.

In the present invention, Sn-I is used as the luminescent metal.
It is not limited to encapsulating the halide of n-Tl-Na, and may be a metal halide lamp encapsulating the halide of Dy-Ho-Tm-Na-Tl. Furthermore, the present invention is not limited to being applied to a downlight type lighting device used for shop lighting or the like.

[0047]

As described above, according to the present invention, since the sealing portion of the arc tube is arranged at the focal position, the temperature rise of the sealing portion is suppressed and the sealing portion is sealed. Oxidation of the metal foil conductor and leakage from this sealing portion are prevented. Further, blackening due to scattering of the electrode substance is prevented, and further, when sodium Na is enclosed, sodium loss is prevented. From this, the life characteristics are improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a reflective discharge lamp according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of the arc tube of the example.

3A and 3B show light distribution characteristics, where FIG. 3A is a conventional light distribution characteristic chart, and FIG. 3B is a light distribution characteristic chart in the case of the structure of FIG.

FIG. 4 is a sectional view of a reflective discharge lamp according to the second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional reflective discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Arc tube 2 ... Bulb 3 ... Sealing part 4 ... Electrode 7 ... Metal foil conductor 10 ... Reflective envelope 12 ... Reflector 15 ... Front glass 16 ... Light control part 18 ... Base 21 ... Main reflection part 22 ... Auxiliary reflection part 23 ... Blocking wall 25 ... Reflection surface 30 ... Lighting circuit 31 ... Power source F ... Focus position O ... Emission center

(72) Inventor Hisanori Sano 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Litec Co., Ltd. (72) Shihisa Kawazuru 4-3-1-1, Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Litec shares In the company

Claims (5)

[Claims] 1. An arc tube in which a pair of electrodes are provided in a bulb and a sealing portion is formed at one end of the bulb, and a reflection surface is formed on an inner surface of a reflector that houses the arc tube and has a focal point. And a reflective envelope having a front opening closed with glass, and the arc tube having the one-sided sealing part at the focal point of the reflective envelope. A reflective discharge lamp that is characterized by 2. The reflection type discharge lamp according to claim 1, wherein the arc tube is filled with a metal halide containing at least sodium. 3. The reflection type discharge lamp according to claim 1, wherein the glass of the reflection type envelope is provided with a light control unit for controlling the distribution of light traveling forward. . 4. The reflection type discharge lamp according to claim 3, wherein the light control unit is a diffusion unit that diffuses light traveling forward. 5. A lighting device for a reflective discharge lamp, comprising: the reflective discharge lamp according to any one of claims 1 to 4; and a lighting circuit for lighting the discharge lamp.