JPH04342950A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a small-sized metal halide lamp which is free from generation of shadow even when an optical system is used while good chromatic characteristics are maintained during the lifetime with the starting characteristic improved. CONSTITUTION:At least metal halide is encapsulated in a light emission tube 1 of transparent heat resistant glass, which generates arcs of 10mm long or less and has a capacity of 1cc or less. A carrier consisting of quartz glass is covered with a radiative substance, and thereover a film of quartz glass is applied to form a sealed radiation source 11, which is put in the tube 1 and sealed. Thus a metal halide lamp is accomplished.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp with improved starting characteristics and used as a light source for video equipment and optical equipment.

0002

[Prior Art] Metal halide lamps are widely used because of their high efficiency and high color rendering properties.Recently, small metal halide lamps have been used for general lighting, and by being combined with reflectors and lenses, they have become popular in automobiles. headlights,
It has come to be used as a light source for optical video equipment, OHPs, etc.

In general, metal halide lamps contain NaI, LiI, KI, RbI, CsI, in addition to mercury and argon.
Alkali metal halides and rare earth metal halides, such as
By enclosing a suitable combination of Sc, In, Tl, Sn, etc., a lamp with a stable arc state can be obtained.

Among these, D using rare earth halides
There are metal halide lamps filled with y-Tl-Cs and Dy-Nd-Cs halides. These are N
Since no a, Li halide is used, there is no light emission that would adversely affect the color rendering evaluation in the visible range, and it is possible to provide high color rendering properties, and in fact, the color rendering index (Ra), red color index (R9) 90 or more lamps were obtained in both cases. Furthermore, a small arc tube with an inner volume of 0.4 cc, an arc length of 5 mm, and an inner diameter of 8 mm, which is filled with such a combination of additives, can also provide similar excellent color rendering properties and is becoming popular for optical applications.

However, lamps containing rare earth halides generally have a high starting voltage, and even in lamps using thoriated tungsten electrodes doped with thorium or thorium oxide, charged particles emitted from the thorium in the electrodes alone are insufficient. , for example, Special Public Interest Publication No. 60-342
As described in Publication No. 20, etc., it is not possible to obtain enough charged particles to start a discharge, and α is emitted.
In the case of electrons emitted from wires or secondary sources, there is a possibility that even if a high starting pulse voltage is applied to the lamp, the lamp will not start for several minutes.

In order to improve such starting characteristics, a method has been considered in which a radiation source is enclosed within an arc tube, as shown in Japanese Patent Laid-Open No. 51-66174. However, this method involves encapsulating an unsealed radiation source, and it is difficult to handle such an unsealed radiation source due to revised laws and regulations, and a sealed radiation source is now essential. There have been various proposals for methods of manufacturing radiation sources, one example of which is shown in Japanese Patent Application Laid-Open No. 52-41798.

[0007]By the way, the special public interest public corporation Sho 60-34220, 34
Publications Nos. 221, 34222, and 34224 disclose metal halide lamps using sealed radiation sources,
The sealed radiation source may be configured by dispersing radioactive substances in a ceramic carrier made of a composite oxide such as zeolite, metal oxide, metal carbide, metal nitride, etc., or by dispersing the radioactive substance in a ceramic carrier. After that, the ceramic carrier is further covered with a coating.

[0008]

[Problems to be Solved by the Invention] By the way, a sealed radiation source constructed by the method disclosed in the above publication is attached to an arc tube 1 having an internal volume of 0.4 cc and an arc length of 5 mm as shown in FIG. CsI weight ratio: 4:
I applied it as is to a small metal halide lamp with a rated power of 150 W containing 0.8 mg of 2:3. In Figure 2, 2 is an electrode, 3 is a molybdenum foil, 4 is an external lead wire, 5 is a heat insulating film, 6 is a reflector, 7 is a nickel lead, 8 is a base, 9 is a connection terminal, and 10 is a sealed radiation source. be.

When a lighting test was conducted with the arc tube 1 in a horizontal position as shown in the figure, the starting voltage decreased and stable starting characteristics were obtained. , a new problem arises in that a shadow of the sealed radiation source 10 is generated.

Furthermore, the rare earth iodide sealed in the arc tube reacts with the ceramic carrier in which the radioactive substance is sealed and dispersed at high temperatures, which not only damages the shape of the ceramic carrier, but also damages the ceramic carrier due to the reaction. It has been found that products containing, for example, Na, Li, etc. released from the carrier have a significant influence on lamp characteristics and color rendering.

The present invention was made to solve the above-mentioned problems that occur when a sealed radiation source is applied to a metal halide lamp used with an optical system, and it improves startability and maintains good color characteristics throughout its life. However, it is an object of the present invention to provide a small metal halide lamp that does not produce shadows even when using an optical system.

0012

[Means and effects for solving the problems] In order to solve the above problems, the present invention provides an arc tube made of light-transmitting heat-resistant glass having an arc length of 10 mm or less and an internal volume of 1 cc or less. In a metal halide lamp that is used with a reflector and/or lens without providing a metal halide lamp, at least metal halide is sealed in the arc tube, a radioactive substance is coated on a carrier made of quartz glass, and a thin film made of quartz glass is further coated on the carrier. This is a sealed radiation source that has been subjected to the following steps.

In the metal halide lamp constructed in this way, the starting level is lowered by the charged particles from the sealed radiation source, and the starting performance is improved, and since the carrier of the sealed radiation source is made of quartz glass, it is possible to improve the starting performance. It is possible to obtain a metal halide lamp which has excellent luminosity and does not produce shadows even when used with an optical system, has little reaction with the enclosed metal halide, and has little change in color characteristics due to reaction products.

[0014]

[Example] Next, an example will be explained. FIG. 1 is a diagram showing an embodiment of the metal halide lamp according to the present invention, which has an internal volume of 0.4c, similar to the conventional lamp shown in FIG.
c, DyI3 in a quartz arc tube 1 with an arc length of 5 mm
A metal halide lamp is constructed by enclosing 0.8 mg of -NdI3 -CsI in a weight ratio of 4:2:3. In the figure, 2 is an electrode, 3 is a molybdenum foil for airtight sealing, 4 is an external lead wire, and 5 is a heat insulating film. In this embodiment, a sealed radiation source 11 configured as follows is enclosed. That is, the amount of radioactivity was 3.7 x 103 on the surface of a carrier with a diameter of 1.0 mm made of quartz glass, which is the same material as the arc tube material.
A sealed radiation source 11 is coated with a radioactive material (for example, technetium-99) that emits only β-rays with an energy of about Bq and an energy of 0.8 MeV or less, and a thin quartz film is applied to the surface of the sealed radiation source 11, which is attached to the inner wall of the arc tube 1. It is melted, fixed and sealed.

In the metal halide lamp thus constructed, the starting level is lowered by the charged particles from the sealed radiation source 11, and the starting performance is improved.
Since the carrier of the sealed radiation source 11 is made of quartz glass, it has excellent translucency and does not produce shadows when used with an optical system. Furthermore, since quartz glass is used as a carrier, there is little reaction with the encapsulated rare earth iodide, and no deterioration in color rendering properties due to reaction products occurs.

The present invention is directed to a lamp comprising an arc tube with an internal volume of 1 cc or less and an arc length of 10 mm or less for the following reasons. That is, in a large arc tube with an internal volume of more than 1 cc and an arc length of more than 10 mm, even if a small opaque body exists, it will not cast a shadow or be noticeable. Therefore, the present invention is directed to small arc tubes having the above-mentioned dimensions or less.

[0017] In the above embodiment, the sealed radiation source was fused and fixed to the inner wall of the arc tube, but the same effect can be obtained even if the sealed radiation source coated with a quartz thin film is simply sealed inside the arc tube. .

[0018]

[Effect of the invention] As explained above based on the embodiments,
According to the present invention, since a sealed radiation source with translucent quartz as a carrier is used, the startability is improved and the metal halide material maintains good color characteristics throughout its life and does not produce shadows even when used with an optical system. lamp can be realized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a metal halide lamp according to the present invention.

FIG. 2 is a diagram showing a configuration example of a conventional metal halide lamp.

[Explanation of symbols]

1 Arc tube 2 Electrode 3 Molybdenum foil 4 External lead wire 5　Heat insulation membrane 11 Sealed radiation source

Claims (2)

[Claims] [Claim 1] An arc tube made of translucent heat-resistant glass having an arc length of 10 mm or less and an internal volume of 1 cc or less,
In a metal halide lamp which is used with a reflector and/or lens without an outer tube, at least a metal halide is sealed in the arc tube, a radioactive substance is coated on a carrier made of quartz glass, and a carrier made of quartz glass is further coated on the carrier. A metal halide lamp characterized in that a sealed radiation source made of a thin film is added and sealed. 2. The metal halide lamp according to claim 1, wherein the arc tube is made of the same material as the carrier of the sealed radiation source.