JPH03274653A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To prevent a lamp from becoming large and lower the unevenness of illuminance of the lamp and improve the service life and light emitting efficiency of the lamp by forming a heat-resistant, warmth retaining, and light reflective film in 40-70% of the surface area of the light emitting part in the electrode side. CONSTITUTION:A metal halide lamp is composed to have a warmth retaining film 5 in 40-70% of surface area of a light emitting tube 1 in the electrode 2 side isolated from the bottom of a reflective plate 8. In the case that the warmth retaining film 5 is formed like this, convection of additives is accelerated and tungsten-halogen cycle owing to halide evaporation becomes active and blackening is well generated. Consequently, while a light emitting tube 1 being prevented from becoming large and unevenness of illuminance because of sealing additives being inhibited, a long service life and high light emitting efficiency of the lamp is achieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a metal halide lamp device, and in particular to a metal halide lamp device that is equipped with a reflector and used as a relatively small video light source that distributes light in an optically limited area. It relates to a lamp device.

[Prior Art] Conventionally, small short-arc metal halide lamps, which are constructed by integrally or removably combining an arc tube and a reflector without using an outer tube, have good color rendering properties and high luminous efficiency. Due to these characteristics, it is being used in overhead projectors, overhead type LCD projection televisions, movie projectors, etc., and is becoming popular.

These devices are becoming more compact, and the metal halide lamps used as their light sources are
The degree of horizontal lighting is increasing. Conventionally, metal halide lamps used in such devices have a rated lamp power of 150 W, for example, with an electrode open circuit of 115 m.
, an almost spherical arc tube with a maximum diameter of 11 m and a pronation diameter of 8.8 m is filled with mercury and about 15 Qtorr of argon as a starting auxiliary gas to achieve a predetermined lamp voltage. Neodymium chloride and cesium iodide were selected in a weight ratio of 4:2:3, respectively, and the internal volume was 0.4c.
0.5■ is enclosed for c and I is used.

[Problems to be Solved by the Invention] By the way, in order to extend the life of metal halide lamps, measures are usually taken to increase the internal volume of the arc tube relative to the applied electric power, and also to increase the luminous efficiency. In order to increase the luminance, measures are taken to increase the amount of additives sealed in the arc tube.

However, in metal halide lamps used for video, when the light source size increases in order to extend the lifespan, the problem arises that the device becomes larger when light distribution is taken into account. If the amount of the additive is increased, the absorbing properties of the additive will cause uneven illuminance and color on the video screen, making it extremely uncomfortable.

The present invention was made to solve the above-mentioned problems with conventional metal halide lamps, and it extends the lifespan and improves luminous efficiency without increasing the size of the arc tube or causing uneven illuminance or color. The purpose of the present invention is to provide a metal halide lamp device that can be measured.

[Means and effects for solving the problem] In order to solve the above problems, the present invention provides a reflector having a reflective surface such as a paraboloid or an ellipsoid, and an axis in which the axis connecting the electrodes is the reflector. In a metal halide lamp device comprising a metal halide lamp without an outer tube arranged in front of the reflector so as to coincide with the central axis, the surface area occupied by the light emitting part on the electrode side of the metal halide lamp remote from the bottom of the reflector. 40 to 70% of the surface area is coated with a heat-resistant and heat-retaining film having light reflectivity.

By providing such a heat-resistant and heat-retaining film having light-reflecting properties, convection of additives is promoted, thereby actively carrying out the tungsten-halogen cycle by halide vapor, and thereby significantly reducing the occurrence of blackening. Therefore, it is possible to extend the lifespan and improve the luminous efficiency while preventing the occurrence of uneven illumination and color due to an increase in the size of the arc tube and an increase in the amount of additives enclosed.

[Example] Next, an example will be described. FIG. 1 is a plan view showing a section of a reflector portion of an embodiment of a metal halide lamp device according to the present invention. In the figure, 1 is the maximum diameter φ11
m+, an arc tube made of quartz tare with an inner diameter of 8.8 m and an internal volume of 0.4 cc. Inside the arc tube 1, electrodes 2.2' are provided at both ends so that the electrodes are open circuit j[5■]. It is being Electrode 2.2' is φ0.45 × length 6.5-1.7
A pure tungsten coil with a diameter of 0.32 mm and a length of 2.5 mm is attached to the tungsten horizontal bar containing 0.5 mm from the tip.
It is formed by being tightly rolled apart from the temple. And this electrode 2.
A molybdenum edge stamping foil 3.3' with a width of 1.5 mm and a length of 12 mm is welded to 2' to maintain airtightness with the quartz arc tube l. A wire 4.4' made of molybdenum wire is provided for supplying power from the outside.Inside the arc tube 1 is mercury.

In addition to argon, three types of iodides, namely dysprosium iodide, neodymium iodide, and cesium iodide, were selected in a weight ratio of 4:"2:3 as in the conventional one.
．． 5 ■ Enclosed. Then, a light-reflective heat-resistant heat insulating material 1115 made of, for example, a ^1203-5iO are doing.

The arc tube l constructed in this way has its wire 4
4' to the cap 6 and nickel lead wire 7, respectively.
A parabolic cold mirror reflector 8 made of hard glass with a diameter of φ90++a and f=15 is attached to surround the arc tube 1 so that its center axis coincides with the axis of the arc tube 1, and a lead wire is attached. One end of the reflector 7 is led out to the outside of the reflector 8 and connected to a terminal 9 to constitute a metal halide lamp device.

When a metal halide lamp device configured in this way is lit at a rating of 150W using a square wave, the total luminous flux is 100Q.
O1+*, Ra85. It exhibits light emitting characteristics with a color temperature of 7000 K and a light emitting efficiency of 671+*/w, making it an excellent light source for images. When the screen illuminance was measured using a fixed optical system, an average illuminance of 25,001 was obtained, and no unevenness in illumination or color occurred.

Also, the average illuminance of the screen after 500 hours of lighting is 2100.
1x, and the life characteristics are also significantly improved. Furthermore, the luminous efficiency is improved as described above because the amount of light increases due to the increase in vapor pressure due to the large-area heat insulating film, and the reflected light from the heat insulating film is effectively utilized.

In the present invention, a light-reflecting heat-resistant insulation film is applied to 40 to 70% of the entire luminous area of the arc tube surface.Next, an experiment conducted to set this condition will be explained. .

First, a lamp was constructed in which a white heat-retaining film was applied to the surface of the arc tube up to a position corresponding to the tip of one electrode 2', and the light emission characteristics were measured. In this case, the coverage of the heat insulating film over the entire luminescent area is approximately 20%.

The light emission characteristics are the same as those of the above example, and when the screen illuminance was measured, it was the same < 2 at the initial stage of lighting.
An average illuminance of 5001x was obtained, but after 500 hours of lighting, the average illuminance suddenly decreased to 18001x.

In order to investigate the cause of the decrease in illumination, we analyzed this lamp and found that the entire arc tube had turned black, which deteriorated the luminous flux and lowered the average illuminance. This blackening is considered to be due to the following reasons. That is, when the coverage of the heat insulating film is as low as about 20%, there is little iodide vapor because the effect of warming the additive is small. In a tungsten electrode, tungsten evaporates due to the temperature at the starting point of the arc, but the amount of evaporation is suppressed by the halogen iodide. However, as mentioned above, when the amount of iodide vapor is small, tungsten sputters from the tungsten electrode increases, which causes blackening.

Furthermore, we tested lamps with various heat insulating film coverages and investigated the relationship between the occurrence of blackening and the heat insulating film coverage.
It has been found that in order to effectively prevent the occurrence of blackening, it is necessary to apply the heat insulating film at a coverage rate of 40% or more of the area of the light emitting part. Furthermore, if the coverage of the heat insulating film exceeds 70%, the heat insulating properties may become too large and the arc tube may swell, so the upper limit of the coverage of the heat insulating film must be 70%.

Next, we created a metal halide lamp with a heat-resistant insulation film coated with a carbon-based black material at a coverage rate of 50% in the same manner as in the above example, and determined the screen illuminance characteristics. An average illuminance of 14,501x was obtained after lighting for 500 hours. This illuminance characteristic has the effect of preventing blackening caused by halide vapor, and a sufficient illuminance maintenance rate has been obtained, but since a heat-retaining film that does not have light reflection properties is applied, the optical path in the direction shown by the arrow in Figure 1 is It was found that the initial screen illuminance decreased as a result. Therefore, it is necessary to form the heat-retaining film from a material having white light-reflecting properties.

As a result of the above experiments, in the present invention, a light-reflecting film is used as the heat-resistant insulation film, and the coverage rate is 4.
It is set to 0 to 70%.

One possible way to increase luminous efficiency is to increase the wall load of the arc tube, so when the lamp was lit with a wall load 1.2 times that of a typical metal halide lamp, the coverage rate of the heat insulating film was Regardless, it has been found that the arc tube becomes devitrified, resulting in a significant rate of illuminance deterioration. Therefore, it is impossible to increase the wall load for the purpose of increasing luminous efficiency.

The present invention can easily extend life and improve luminous efficiency by simply setting the coating coverage of the heat-retaining film without increasing the wall surface load. In addition, in arc tubes with a heat-retaining film coverage of less than 40%, the surface temperature of the arc tube is non-uniform during lighting, and the encapsulated additives are not distributed uniformly, but are distributed unevenly in a certain part. ing. Therefore, the light that passes through the colored additive liquid causes uneven color and uneven illuminance, but in the present invention, the coverage is set at 40 to 70%, so the surface of the arc tube temperature can be made uniform,
Therefore, since the additive distribution is also made uniform, it is possible to reduce the occurrence of uneven illumination and color.

[Effects of the Invention] As explained above based on the embodiments, according to the present invention, the blackening speed can be delayed and the service life can be extended without increasing the size of the arc tube or increasing the amount of additives included. At the same time, it is possible to improve luminous efficiency and further reduce the occurrence of uneven illuminance and color.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a cross section of a reflector of an embodiment of a metal halide lamp device according to the present invention. In the figure, 1 is an arc tube, 2.2' is an electrode, 33' is an edge stamping foil, 4.4' is a wire, 5 is a heat insulating film, 6 is a base, 7 is a lead wire, 8 is a reflective plate, and 9 is a Indicates terminal.

Claims (1)

[Claims] 1. A metal halide without an outer tube arranged in front of the reflector so that the axis connecting the electrodes and the reflector having a reflective surface such as a paraboloid or an ellipsoid coincides with the central axis of the reflector. In a metal halide lamp device comprising a lamp, the surface area occupied by the light emitting part on the electrode side remote from the bottom of the reflection plate of the metal halide lamp is
A metal halide lamp device characterized in that 70% of the surface area is coated with a heat-resistant and heat-retaining film having light reflectivity.