JP2000215851A - Metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the luminous efficiency of a metal halide discharge tube by arranging an IR dichroic mirror reflecting infrared rays or/and a UV filter absorbing ultraviolet rays as an optical filter at a translucent section. SOLUTION: A translucent section 3 is provided on the front face of an envelope 2, and the translucent section 3 is covered with a front lens 4. A metal halide discharge tube 5 is arranged in the envelope 2, and a reflecting face is formed on the inner face of the envelope 2. An IR dichroic mirror 6 reflecting the light in the infrared ray range is coated on the front face of the front lens 4 as an optical filter. The IR dichroic mirror 6 reflects only the light in the infrared ray range within the light emitted from the metal halide discharge tube 5 and transmits visible light. Infrared rays are returned to the inside to heat the metal halide discharge tube 5, the halogen vapor pressure in the metal halide discharge tube 5 is increased, and luminescence intensity is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel metal halide lamp. Specifically, the present invention relates to a technique for improving luminous efficiency.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional metal halide lamp.

The metal halide lamp a has an envelope b, a light-transmitting portion c is provided on the front surface of the envelope b, and a front lens d is attached to the hole c. A metal halide discharge tube e is provided inside the envelope b.

In the metal halide lamp a, the envelope b has a function of preventing the fragments and the like from scattering when the metal halide discharge tube e ruptures inside.

[0005]

In the metal halide lamp a, the halogen pressure inside the metal halide discharge tube e is reduced as shown in FIG.
As shown in the figure, the emission intensity tends to increase as the value increases. For this purpose, the reflector f formed on the inner surface of the envelope b is formed so as to reflect infrared rays.
The pressure inside the metal halide discharge tube e cannot be increased to about 150 atm or more.

The electrodes g, g 'and g' inside the metal halide discharge tube e (shown in FIG. 8) are hot, but the electrodes g, g ", g near the roots of the electrodes g. The temperature of "" is relatively low, and halogen activated by discharge is condensed in this portion, resulting in a decrease in the overall light emission intensity.

Since the light emitted from the light transmitting portion c of the metal halide lamp a includes infrared light and ultraviolet light, a heat-resistant and light-resistant component is used for the optical unit including the metal halide lamp a. Or a component that is sensitive to infrared light or ultraviolet light needs to be arranged sufficiently away from the metal halide lamp a.

Therefore, the present invention has been made in view of the above circumstances, and has as its object to improve the luminous efficiency of a metal halide discharge tube.

[0009]

According to the present invention, there is provided a metal halide lamp in which an optical filter is provided in a light transmitting portion of an envelope in order to solve the above-mentioned problems.

Therefore, in the metal halide lamp according to the present invention, the luminous efficiency of the metal halide discharge tube provided inside the envelope is enhanced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the metal halide lamp of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the metal halide lamp of the present invention.
1 shows the first embodiment of the present invention.

A light transmitting portion 3 is provided on the front surface of the envelope 2.
The through hole 3 is covered by a front lens 4. A metal halide discharge tube 5 is provided in the envelope 2. In addition, a reflection surface is formed on the inner surface of the envelope 2.

FIG. 2 shows a front view of the front lens 4.
An IR (Infrared Radiation) dichroic mirror 6 that reflects light in the infrared region (wavelength 700 nm or more) as shown in FIG.
The IR dichroic mirror 6 is formed directly on the surface of the front lens 4 by a vacuum evaporation method or a sputtering method, and reflects only infrared light out of the light radiated from the metal halide discharge tube 5 to generate visible light. Is transmitted.

Normally, the metal halide discharge tube 5 has electrodes 7,
The internal halogen is activated by the discharge between the electrodes 7 to emit light. The pressure in the metal halide discharge tube 5 is 150 at the time of discharge.
It is about atmospheric pressure. It is well known that the higher the pressure, the higher the emission intensity. In the metal halide lamp 1, the infrared light reflected by the IR dichroic mirror 6 coated on the front lens 4 returns to the inside and heats the metal halide discharge tube 5, so that the halogen vapor inside the metal halide discharge tube 5 is vaporized. The pressure will increase and the emission intensity will increase.

The infrared light reflected by the IR dichroic mirror 6 also has a high temperature near the bases of the electrodes 7, 7 inside the metal halide discharge tube 5, and condenses on the bases of the electrodes 7, 7. Activate the halogen, which also increases the emission intensity.

Further, since infrared light is cut off from the light radiated from the metal halide lamp 1 by the IR dichroic mirror 6, an increase in the temperature of the optical unit including the metal halide lamp 1 is suppressed, and optical components which are weak to heat. For example, a plastic lens 8 or the like can be used (see FIG. 3).

Although the IR dichroic mirror 6 is shown as being coated on the front surface of the front lens 4, it may be formed on the inner surface of the front lens 4.

FIG. 4 shows a second example of the metal halide lamp of the present invention.
1A of the first embodiment.

In the metal halide lamp 1A according to the second embodiment, the optical filter formed on the front lens 4 is different from that of the first embodiment only, and the other parts are the same as those of the first embodiment. This is the same as that in the first embodiment. Therefore, only the different points will be described in detail, and the other points will be denoted by the same reference numerals as those of the same parts in the first embodiment, and description thereof will be omitted.

In the metal halide lamp 1A, a UV (Ultraviolet Radiation) filter 9 for absorbing ultraviolet light is coated on the front surface of the front lens 4 as an optical filter. Accordingly, since ultraviolet light is cut off from the light radiated from the metal halide lamp 1A by the UV filter 9, in the optical unit including the metal halide lamp 1A, an optical component having poor light resistance due to ultraviolet light, for example, a plastic lens 8 or the like is used. (See FIG. 4).

In the metal halide lamp 1A, the UV filter 9 may be formed on the inner surface of the front lens 4.

FIG. 5 shows a third embodiment 1B of the metal halide lamp of the present invention in which an IR dichroic mirror 6 and a UV filter 9 are superposed and coated on the front surface of a front lens 4. In the metal halide lamp 1B according to the third embodiment, the optical filter formed on the front lens 4 is different from that in the first embodiment only. The same reference numerals as in the first embodiment denote the same parts, and a description thereof will be omitted.

In the metal halide lamp 1B according to the third embodiment, infrared light is cut off by the IR dichroic mirror 6 and ultraviolet light is cut off by the UV filter 9 from the light emitted from the metal halide lamp 1B. Therefore, in the optical unit including the metal halide lamp 1B, an optical component weak to heat or an optical component weak to ultraviolet rays, for example, a plastic lens 8 can be used (see FIG. 5).

In this metal halide lamp 1B, the IR dichroic mirror 6 and the UV filter 9
May be formed on the inner surface of the front lens 4,
Alternatively, one of the IR dichroic mirror 6 and the UV filter 9 may be formed on the front surface of the front lens 4 and the other may be formed on the inner surface of the front lens 4.

It should be noted that the shapes and structures of the respective parts shown in the above-described embodiments are merely examples of the specific embodiments to be carried out when carrying out the present invention. The scope should not be construed as limiting.

[0027]

As is apparent from the above description, the metal halide lamp of the present invention is a metal halide lamp in which a metal halide discharge tube is provided in an envelope having a light-transmitting portion. An optical filter is provided in the section.

Therefore, in the metal halide lamp of the present invention, the luminous efficiency of the metal halide discharge tube disposed inside the envelope is enhanced by the action of the optical filter.

According to the second aspect of the present invention, the optical filter is an IR (Infrared Rad) that reflects infrared light.
iation) Since the dichroic mirror is used, the temperature of the metal halide discharge tube rises due to the infrared light reflected by the IR dichroic mirror and returned into the envelope, and the pressure inside the metal halide discharge tube rises. The luminous efficiency increases.

Further, since the base of the electrode of the metal halide discharge tube becomes hot due to the infrared light returned into the envelope, halogen condensed at the base of the electrode is activated. The luminous efficiency of the metal halide discharge tube increases.

Furthermore, since infrared light is cut off from the light emitted from the metal halide lamp, an optical component that is weak to heat can be used for the optical unit including the metal halide lamp.

According to the third aspect of the present invention, the optical filter is provided with a UV (Ultraviolet) absorbing ultraviolet light.
Since the filter is an Rdiation) filter, ultraviolet light is cut off from the light emitted from the metal halide lamp by the UV filter. Therefore, in an optical unit including the metal halide lamp, an optical component having poor light resistance due to ultraviolet light can be used.

In the invention described in claim 4, the optical filter is an IR dichroic mirror that reflects infrared light and a UV filter that absorbs ultraviolet light. , I
Infrared light and UV light by R dichroic mirror
Since ultraviolet light is cut by the filter, it is possible to use an optical component that is sensitive to heat or an optical component that is sensitive to ultraviolet light in an optical unit including a metal halide lamp.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the metal halide lamp of the present invention together with FIGS. 2 and 3, which is a schematic longitudinal sectional view.

FIG. 2 is a graph showing optical characteristics of an IR dichroic mirror.

FIG. 3 is a schematic longitudinal sectional view showing one operation.

FIG. 4 is a schematic longitudinal sectional view showing a second embodiment of the metal halide lamp of the present invention.

FIG. 5 is a schematic longitudinal sectional view showing a third embodiment of the metal halide lamp of the present invention.

FIG. 6 is a schematic longitudinal sectional view showing an example of a conventional metal halide lamp.

FIG. 7 is a graph showing the relationship between the pressure inside the metal halide discharge tube and the emission intensity.

FIG. 8 is an enlarged sectional view showing a metal halide discharge tube.

[Explanation of symbols]

1: Metal halide lamp, 2: envelope, 3: translucent part,
5: Metal halide discharge tube, 6: IR dichroic mirror (optical filter), 1A: Metal halide lamp, 9: UV filter (optical filter), 1B: Metal halide lamp

Claims (4)

[Claims] 1. A metal halide lamp in which a metal halide discharge tube is provided in an envelope having a light transmitting portion, wherein an optical filter is provided in the light transmitting portion. 2. The metal halide lamp according to claim 1, wherein the optical filter is an IR (Infrared Radiation) dichroic mirror that reflects infrared light. 3. The metal halide lamp according to claim 1, wherein the optical filter is a UV (Ultraviolet Radiation) filter that absorbs ultraviolet light. 4. The metal halide lamp according to claim 1, wherein the optical filter is an IR dichroic mirror that reflects infrared light and a UV filter that absorbs ultraviolet light.