JPH04303508A - Lighting device - Google Patents

Abstract

PURPOSE:To prolong the life of a gas discharge lamp by preventing losing alkali metal included in a sealed gas, from the inside of the gas discharge lamp. CONSTITUTION:An alkali metal halide is sealed in an arc tube body 2 of a gas discharge lamp 1. A reflecting body 3a is arranged optically opposite to the gas discharge lamp 1. An opposite surface part 6 of the reflecting body 3a facing the gas discharge lamp 1 is coated with a dielectric having transparency to be in an electrically insulated condition.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device used, for example, for floodlighting outdoor sports facilities.

0003

2. Description of the Related Art Generally, this type of lighting device includes a gas discharge lamp and a metal reflector placed opposite the gas discharge lamp. This gas discharge lamp consists of an arc tube made of heat-resistant quartz glass, and the interior of the arc tube is filled with an alkali metal halide in addition to mercury and an inert gas.

In this lighting device, when the gas discharge lamp is turned on, the alkali metal molecules separated from the alkali metal halide are ionized and excited to emit light, and the gas discharge lamp emits light. The irradiated light then irradiates the object to be irradiated, either directly or by being reflected by a reflector.

[0005]

[Problems to be Solved by the Invention] However, in the gas discharge lamps used in the above-mentioned conventional lighting devices, alkali metal is lost from the inside of the arc tube body during lighting, so the luminous efficiency decreases, and the lifespan of the gas discharge lamp is shortened. is often shortened. This is because electrons inside the arc tube are generated by ionization of alkali metals, so when the alkali metal is lost from the arc tube, the number of electrons inside the arc tube decreases. Furthermore, since most of the irradiated light is radiated from alkali metal ions, when the number of alkali metal ions decreases, less power is converted into light, and more power is converted into heat. Therefore, the luminous efficiency of the gas discharge lamp will be reduced.

It is also known that this loss of alkali metal from the arc tube body occurs when the alkali metal passes through the arc tube body by photoelectrolysis.
This photoelectrolysis is thought to occur when the alkali metal is attracted to the reflector from the arc tube under the influence of photoelectrons emitted from a metal such as a reflector placed near the arc tube. For this reason, countermeasures such as increasing the distance between the arc tube and the reflector have been taken, making it difficult to downsize the lighting device.

SUMMARY OF THE INVENTION An object of the present invention was made in view of the above-mentioned problems, and is to extend the life of a gas discharge lamp by preventing the alkali metal sealed in the lamp from escaping from the lamp. Our goal is to provide a lighting device that can.

[Configuration of the invention]

[0009]

[Means for Solving the Problems] A lighting device according to claim 1 includes a gas discharge lamp containing an alkali metal in a sealed gas;
A reflector is arranged to optically face the gas discharge lamp, and the reflector is made of metal, and at least a facing surface facing the gas discharge lamp is coated with a dielectric film having translucency. This is what I did.

A lighting device according to a second aspect of the present invention includes a gas discharge lamp containing an alkali metal in the filled gas, and a reflector disposed optically opposite to the gas discharge lamp, the reflector being transparent. It is made of a dielectric material having optical properties, and has a metal thin film formed on the back side of the opposing surface portion facing the gas discharge lamp.

A lighting device according to a third aspect of the present invention includes a gas discharge lamp containing an alkali metal in the gas filled, and a reflector disposed optically opposite to the gas discharge lamp, and the reflector is arranged to face the gas discharge lamp. An optical interference thin film made of a dielectric material is formed on the opposing surface facing the gas discharge lamp.

A lighting device according to a fourth aspect of the present invention includes a gas discharge lamp containing an alkali metal in the gas filled, and a reflector disposed optically opposite to the gas discharge lamp, the reflector being transparent. It is made of a dielectric material having optical properties, and has a plurality of prism parts having an apex angle of about 90 degrees formed on the back side of the opposing face part facing the gas discharge lamp.

[0013]

[Function] In the lighting device according to claim 1, since the opposing surface portion of the metal reflector disposed optically facing the gas discharge lamp is covered with glass, this opposing surface portion is electrically connected to the gas discharge lamp. It is insulated. Therefore, when the gas discharge lamp is lit, the alkali metal sealed in the gas discharge lamp and ionized when lit is prevented from being attracted to the reflector and lost from the inside of the gas discharge lamp. Extend the life of discharge lamps. Furthermore, this reflector reflects the light irradiated from the gas discharge lamp at the opposing surface portion.

[0014] In the illumination device according to claim 2, the dielectric reflector disposed optically facing the gas discharge lamp comprises:
The opposing surface facing the gas discharge lamp is electrically insulated. Therefore, when the gas discharge lamp is lit, the alkali metal sealed in the gas discharge lamp and ionized when lit is prevented from being attracted to the reflector and lost from the inside of the gas discharge lamp. Extend the life of discharge lamps. Further, this reflector has translucency and is provided with a metal thin film on the back side of the opposing surface portion of the reflector, so that the light irradiated from the gas discharge lamp is reflected by this metal thin film. .

In the lighting device according to the third aspect, the reflector disposed optically facing the gas discharge lamp has an optical interference thin film made of a dielectric material on the opposing surface portion of the reflector facing the gas discharge lamp. , so this opposing surface portion is electrically insulated. Therefore, when the gas discharge lamp is lit, the alkali metal sealed in the gas discharge lamp and ionized when lit is prevented from being attracted to the reflector and lost from the interior of the gas discharge lamp. Furthermore, this reflector reflects the light irradiated from the gas discharge lamp at the light interference film on the opposing surface portion.

[0016] In the lighting device according to claim 4, the dielectric reflector disposed optically facing the gas discharge lamp comprises:
The opposing surface facing the gas discharge lamp is electrically insulated. Therefore, when the gas discharge lamp is lit, the alkali metal sealed in the gas discharge lamp and ionized when lit is prevented from being attracted to the reflector and lost from the inside of the gas discharge lamp. Extend the life of discharge lamps. Moreover, since a plurality of prism parts having an apex angle of approximately 90 degrees are formed on the back side of the opposing surface part, the light irradiated from the gas discharge lamp is totally reflected by the inclined surface of the prism part, and the light is reflected by the reflector. The light is emitted from the irradiation aperture. Furthermore, the refractive index in the infrared region is small, the incident angle of the totally reflected light is large, and the reflectance of infrared rays is low, so that less infrared rays are emitted, and thermal damage to the irradiated object is prevented.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the lighting device of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes a gas discharge lamp. In this gas discharge lamp 1, a pair of electrodes (not shown) are sealed in an arc tube body 2 made of quartz glass whose center part is approximately spherical, and mercury is used as the sealed gas. In addition to low-pressure inert gas,
Alkali metal halides containing alkali metals such as lithium (Li) and sodium (Na) are sealed. Furthermore, a reflector 3a is disposed optically opposite the gas discharge lamp 1 to constitute an illumination device 4.

As shown in FIG. 2, this reflector 3a is made of alumite-treated aluminum and has a substantially arcuate cross-section, and the surface of the opposing surface portion 6 facing the gas discharge lamp 1 is electrolytically polished to provide light. forming a reflective surface. moreover,
This opposing surface portion 6 is coated with a dielectric film 7 having light-transmitting properties.

Next, the operation of this embodiment will be explained.

When the gas discharge lamp 1 is turned on, arc discharge occurs between the electrodes. In the center of this arc, the alkali metal halide enclosed in the arc tube body 2 is separated into an alkali metal and a halogen, and the separated alkali metal is ionized. The alkali metal ions are excited and emit light, and the arc tube body 2 emits light having a wavelength specific to the alkali metal. Further, the light irradiated from the arc tube body 2 is directly or reflected by the facing surface portion 6 of the reflector 3a, and irradiates an object to be irradiated (not shown).

Further, although the reflector 3a is made of aluminum, the opposing surface portion 6 facing the gas discharge lamp 1 is covered with a dielectric film 7, so that the opposing surface portion 6 is electrically insulated. It is in a state of being Therefore, the alkali metal ions inside the arc tube body 2 are prevented from being attracted to the reflector 3a, thereby preventing the alkali metal from being lost from the inside of the arc tube body 2. For this reason,
Since there is no need to increase the distance between the arc tube body 2 and the reflector 3a, the lighting device 4 can be downsized.

Furthermore, most of the electrons inside the arc tube body 2 are supplied from alkali metal ions, but since the number of these electrons does not decrease, an increase in the voltage applied to the electrodes is prevented and the arc tube body 2. Suppress the temperature rise.

Furthermore, since the number of alkali metal ions that radiate light does not decrease, the luminous efficiency of the gas discharge lamp 1 is prevented from decreasing. For this reason, the life of the gas discharge lamp 1 can be extended.

Next, a second embodiment of the lighting device of the present invention will be explained based on FIG.

The gas discharge lamp 1 is constructed in the same manner as in the first embodiment, and a reflector 3b is arranged optically opposite to the gas discharge lamp 1 in the same manner as in the first embodiment. A lighting device 4 is configured.

As shown in FIG. 3, the reflector 3b is made of a translucent dielectric material and has a substantially arcuate cross-sectional shape. A metal thin film 9 is formed by vapor depositing aluminum (Al 2 ).

Next, the operation of this embodiment will be explained.

When the gas discharge lamp 1 is turned on, the alkali metal sealed inside the arc tube body 2 is irradiated with light having a specific wavelength, as in the first embodiment. The light emitted from the arc tube body 2 is directed or reflected by the metal thin film 9, and irradiates an object (not shown) to be irradiated.

Further, the reflector 3b is made of a dielectric material having light-transmitting properties, and the metal thin film 9 is formed on the back side of the opposing surface portion 6 of the reflector 3b.
The opposing surface portion 6 facing the gas discharge lamp 1 is electrically insulated. Therefore, the alkali metal ions inside the arc tube body 2 are prevented from being attracted to the reflector 3b, thereby preventing the alkali metal from being lost from the inside of the arc tube body 2. For this reason, the arc tube body 2
Since there is no need to increase the distance between the reflector 3b and the reflector 3b, the lighting device 4 can be downsized.

Furthermore, most of the electrons inside the arc tube body 2 are supplied from alkali metal ions, but since the number of these electrons does not decrease, an increase in the voltage applied to the electrodes is prevented and the arc tube body 2. Suppress the temperature rise.

Furthermore, since the number of alkali metal ions that radiate light does not decrease, the luminous efficiency of the gas discharge lamp 1 is prevented from decreasing. For this reason, the life of the gas discharge lamp 1 can be extended.

Note that the metal thin film 9 provided on the back side of the reflector 3b is not limited to aluminum, but may also be made of silver (Ag).
may be vapor-deposited.

Next, a third embodiment of the lighting device of the present invention will be explained based on FIG. 4.

The gas discharge lamp 1 is constructed in the same manner as in the first embodiment, and a reflector 3c is arranged optically opposite to the gas discharge lamp 1 in the same manner as in the first embodiment. A lighting device 4 is configured.

As shown in FIG. 4, the reflector 3c is made of, for example, plastic and has a substantially arcuate cross-section.
On the surface of the facing surface portion 6 facing the gas discharge lamp 1,
For example, silicon oxide (SiO2) and titanium oxide (T
An optical interference thin film 11 made of a dielectric material such as iO2) is provided.

Next, the operation of this embodiment will be explained.

When the gas discharge lamp 1 is turned on, the alkali metal sealed inside the arc tube body 2 is irradiated with light having a specific wavelength, as in the first embodiment. The light irradiated from this arc tube body 2 is reflected directly or by the light interference thin film 11 of the reflector 3c,
An object to be irradiated (not shown) is irradiated.

Further, since the reflector 3c is made of plastic and the optical interference thin film 11 is made of a dielectric material, this reflector 3c is an electrical insulator. Therefore, the alkali metal ions inside the arc tube body 2 are prevented from being attracted to the reflector 3c, thereby preventing the alkali metal from being lost from the inside of the arc tube body 2. Therefore, there is no need to increase the distance between the arc tube body 2 and the reflector 3c, so the lighting device 4 can be downsized.

Further, the optical interference thin film 11 is made of silicon oxide (S
Since it is formed of a dielectric material such as iO2 ) or titanium oxide (TiO2), the heat resistance of the reflector 3c is improved.

Furthermore, most of the electrons inside the arc tube body 2 are supplied from alkali metal ions, but since the number of these electrons does not decrease, an increase in the voltage applied to the electrodes is prevented and the arc tube body 2. Suppress the temperature rise.

Furthermore, since the number of alkali metal ions that radiate light does not decrease, the luminous efficiency of the gas discharge lamp 1 is prevented from decreasing. For this reason, the life of the gas discharge lamp 1 can be extended.

Although the reflector 3c is made of plastic, it is not limited to this, and as shown in FIG. 5, the same effect can be obtained even if it is made of glass.

Next, a fourth embodiment of the lighting device of the present invention will be described with reference to FIGS. 6 and 7.

The gas discharge lamp 1 is constructed in the same manner as in the first embodiment, and a reflector 3d is arranged optically opposite to the gas discharge lamp 1 in the same manner as in the first embodiment. A lighting device 4 is configured.

As shown in FIGS. 6 and 7, the reflector 3d is made of a light-transmitting dielectric and has a substantially parabolic quadratic cross-sectional shape, and faces the gas discharge lamp 1. A prism section 13 is formed on the back side of the opposing surface section 6. This prism portion 13 has an apex angle of approximately 90 degrees, so that light incident from the opposing surface side 6 is totally reflected on the inclined surface.
It is formed into a substantially isosceles triangle shape.

The reflector 3d has a different refractive index in the visible range and infrared range of incident light; in the infrared range, the refractive index is 1.5 at a wavelength of about 1 to 2 μm, and in the visible range, the refractive index is 1.5. It has a refractive index of 1.52, and has a characteristic that the refractive index decreases as it goes into the infrared region.

Next, the operation of this embodiment will be explained.

When the gas discharge lamp 1 is turned on, the alkali metal sealed inside the arc tube body 2 is irradiated with light having a specific wavelength, as in the first embodiment. The light irradiated from this arc tube body 2 is reflected directly or by the prism part 13 of the reflector 3d,
An object to be irradiated (not shown) is irradiated.

Further, the light emitted from the gas discharge lamp 1 is totally reflected by the inclined surface of the prism portion 13, and is emitted from the irradiation aperture of the reflector 3d. Furthermore, the refractive index in the infrared region is small, and the angle of incidence of the totally reflected light is large, so the reflectance of infrared rays is low, so that less infrared rays are emitted, and thermal damage to the irradiated object is prevented.

Furthermore, since the reflector 3d is made of a dielectric material, the reflector 3d is an electrical insulator. Therefore, the alkali metal ions inside the arc tube body 2 are prevented from being attracted to the reflector 3d, thereby preventing the alkali metal from being lost from the inside of the arc tube body 2. Therefore, there is no need to increase the distance between the arc tube body 2 and the reflector 3d, so the lighting device 4 can be downsized.

Further, most of the electrons inside the arc tube body 2 are supplied from alkali metal ions, but since the number of these electrons does not decrease, an increase in the voltage applied to the electrodes is prevented and the arc tube body 2. Suppress the temperature rise.

Furthermore, since the number of alkali metal ions that radiate light does not decrease, the luminous efficiency of the gas discharge lamp 1 is prevented from decreasing. For this reason, the life of the gas discharge lamp 1 can be extended.

[0054]

According to the lighting device according to claim 1, although the reflector is made of metal, the opposing surface facing the gas discharge lamp is coated with a dielectric material having translucency. , this opposing surface portion is electrically insulated. Therefore, when the gas discharge lamp is lit, the ionized alkali metal sealed in the gas discharge lamp is prevented from being attracted to the reflector, thereby preventing the alkali metal from being lost from the inside of the gas discharge lamp. . Therefore, since there is no need to increase the distance between the gas discharge lamp and the reflector, the lighting device can be downsized. Furthermore, since the alkali metal that radiates light does not decrease, a decrease in luminous efficiency can be prevented. For this reason,
The life of the gas discharge lamp can be extended.

According to the lighting device according to the second aspect, since the reflector is made of a dielectric material having light-transmitting properties, the opposing surface portion facing the gas discharge lamp is electrically insulated. There is. Therefore, when the gas discharge lamp is lit, the ionized alkali metal sealed in the gas discharge lamp is prevented from being attracted to the reflector.
This alkali metal can be prevented from being lost from the inside of the gas discharge lamp. Therefore, since there is no need to increase the distance between the gas discharge lamp and the reflector, the lighting device can be downsized. Furthermore, since the alkali metal that radiates light does not decrease, a decrease in luminous efficiency can be prevented. Therefore, the life of the gas discharge lamp can be extended.

According to the lighting device according to claim 3, since the reflector is provided with a light interference thin film made of a dielectric material on the opposing surface portion facing the gas discharge lamp, this opposing surface portion is electrically insulated. is in a state. Therefore, when the gas discharge lamp is lit, the ionized alkali metal sealed in the gas discharge lamp is prevented from being attracted to the reflector, thereby preventing the alkali metal from being lost from the inside of the gas discharge lamp. . Therefore, there is no need to increase the distance between the gas discharge lamp and the reflector.
The lighting device can be downsized. Furthermore, since the alkali metal that radiates light does not decrease, a decrease in luminous efficiency can be prevented. Therefore, the life of the gas discharge lamp can be extended.

According to the lighting device according to the fourth aspect, since the reflector is made of a dielectric material having translucency, the opposing surface portion facing the gas discharge lamp is electrically insulated. There is. Therefore, when the gas discharge lamp is lit, the ionized alkali metal sealed in the gas discharge lamp is prevented from being attracted to the reflector.
This alkali metal can be prevented from being lost from the inside of the gas discharge lamp. Therefore, since there is no need to increase the distance between the gas discharge lamp and the reflector, the lighting device can be downsized. Furthermore, since the alkali metal that radiates light does not decrease, a decrease in luminous efficiency can be prevented. Therefore, the life of the gas discharge lamp can be extended. Furthermore, since the prism section is provided on the back side of the opposing surface section of the reflector, the light irradiated from the gas discharge lamp is totally reflected by the inclined surface of the prism section and can be emitted from the irradiation aperture of the reflector. can. In addition, the refractive index in the infrared region is small, and the angle of incidence of the totally reflected light is large, so the reflectance of infrared rays can be lowered, so less infrared rays are emitted, and thermal damage to the irradiated object can be prevented. .

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a lighting device showing a first embodiment of the lighting device of the present invention.

FIG. 2 is a sectional view of the reflector shown above.

FIG. 3 is a sectional view of a reflector of a lighting device showing a second embodiment of the lighting device of the present invention.

FIG. 4 is a sectional view of a reflector of a lighting device showing a third embodiment of the lighting device of the present invention.

FIG. 5 is a sectional view showing another configuration of the reflector as above.

FIG. 6 is a perspective view of a prism section provided on a reflector of a lighting device showing a fourth embodiment of the lighting device of the present invention.

[Explanation of symbols]

1 Gas discharge lamp 3a-3d Reflector 4. Lighting device 6 Opposing surface part 9 Metal thin film 11 Optical interference thin film 13 Prism section

Claims (4)

[Claims] 1. A gas discharge lamp containing an alkali metal in a filled gas, and a reflector disposed optically opposite to the gas discharge lamp, the reflector being made of metal and at least A lighting device characterized in that a facing surface portion facing a lamp is coated with a dielectric film having translucency. 2. A gas discharge lamp containing an alkali metal in a filled gas, and a reflector disposed optically opposite to the gas discharge lamp, the reflector being made of a dielectric material having translucency. A lighting device characterized in that a metal thin film is formed on the back side of the opposing surface portion facing the gas discharge lamp. 3. A gas discharge lamp containing an alkali metal in a filled gas, and a reflector disposed optically opposite to the gas discharge lamp, wherein the reflector A lighting device characterized in that a light interference thin film made of a dielectric material is formed on a surface portion. 4. A gas discharge lamp containing an alkali metal in a filled gas, and a reflector disposed optically opposite to the gas discharge lamp, the reflector being made of a dielectric material having translucency. A lighting device characterized in that a plurality of prism portions having an apex angle of approximately 90 degrees are formed on the back side of the opposing surface portion facing the gas discharge lamp.