JPH04329252A - Metal halide lamp device - Google Patents

Abstract

PURPOSE:To enlarge illuminance of a screen to eliminate unevenness of the screen by forming a reflecting and temperature insulating film on the outer surface of a lamp in the peripheral part of an electrode positioned in an opening part of a reflecting mirror, and forming multiple projecting parts or recessed parts in the outer surface where the heat insulating film is not formed. CONSTITUTION:A reflecting and heat insulating film 3, which is made of alumina-silica mixture and has light reflecting property and heat resistance, is coated for formation on the outer surface of a light emitting tube corresponding to the peripheral part of an electrode 2a positioned in the opening port 7a side of a reflecting mirror 7. Furthermore, the outer surface of a light emitting part 1a of an electrode 2b positioned from the edge 3a of the film 3 to the bottom side 7b of the reflecting mirror 7 is formed into clear surface, and projecting parts 4 are formed on that clear surface. Wires of that light emitting tube are connected to a nickel lead 5 and a base 6, and the reflecting mirror 7, of which inside surface is coated with the cold mirror film, is fitted so that a center axis thereof coincide with the axial core of the light emitting tube, and one end of the lead wire is led out to the outside of the reflecting mirror 7 to be connected to a terminal 8.

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 device, and more particularly to a metal halide lamp device that is used as a light source for relatively small optical and video equipment that distributes light in an optically limited area in combination with a reflecting mirror. .

0002

[Prior Art] Conventionally, a small metal halide lamp device constructed by integrally or removably combining an arc tube and a reflecting mirror without using an outer bulb has good color rendering properties and high luminous efficiency. Due to these characteristics, it is increasingly being used as a light source for overhead projectors, overhead-type liquid crystal projectors, liquid crystal projection televisions, movie projectors, etc.

As shown in FIG. 8, the metal halide lamp used in these applications, for example, has a rated lamp power of 150 W, and has a nearly spherical arc tube 101 with a distance between electrodes of 5 mm, a maximum outer diameter of 11 mm, and a maximum inner diameter of 8.8 mm. In addition to filling the lamp with mercury and argon as a starting aid gas at approximately 200 torr to achieve a predetermined lamp voltage, dysprosium iodide, neodymium iodide, and cesium iodide were also added.
The weight ratio of each was selected to be 4:2:3, and 0.7 mg was sealed for an internal volume of 0.4 cc. The arc tube 101 has wires at both ends connected to a nickel lead wire 102 and a base 103, and a reflecting mirror 104 made of hard glass and having a cold mirror film on the inner surface, which surrounds the arc tube, is attached to the center of the arc tube 101. It is attached so that its axis substantially coincides with the axis of the arc tube, and one end of the lead wire 102 is led out to the outside of the reflector and connected to a terminal 105, thereby forming a metal halide lamp device 111.

When the metal halide lamp device configured as described above is used as a light source for a liquid crystal projector, the metal halide lamp device is placed vertically facing downward, and images are projected onto a screen via a total reflection mirror, a liquid crystal panel, and a projection lens. It is composed of

By the way, in the conventional metal halide lamp used in the above-mentioned optical device, as shown in FIG. 8, a reflective and heat-insulating film 106 is formed on the outer surface of the lamp arc tube located on the opening side of the reflecting mirror 104. The outer surface of the lamp is a clear surface. When this metal halide lamp is lit with the clear surface placed inside the bottom of the reflector as shown in the figure, assuming that the light-emitting part of the arc of the arc tube is located on the central axis of the arc tube, the light-emitting part will be clearer than the light-emitting part. The light emitted toward the surface passes through the clear surface almost linearly without being scattered.

Therefore, when projecting on a 40-inch screen with an aspect ratio of 3:4 as shown in FIG. 7 as an optical device,
Straight light emitted from a metal halide lamp through a clear surface is reflected by a reflecting mirror near the lamp, and reaches the screen through a lens system. The amount of straight light that passes through this clear surface is almost unscattered and becomes a considerable amount, and the amount of straight light that is emitted to the part of the reflector near the arc tube is reflected because its eccentricity is small. Therefore, when the illuminance distribution along the line AA' on the screen is measured, as shown by curve a in FIG. 6, the illuminance near the center is extremely high, but the peripheral illuminance is extremely low. Then, the illuminance ratio regarding the illuminance measured at the measurement points ■ to ■ at the center of each of the areas divided into nine equal parts of the screen is calculated as follows: illuminance ratio (%) = minimum illuminance value among the measurement points ■ to ■ / center illuminance value When expressed as (illuminance value of ■) x 100, when a metal halide lamp with a clear surface for most of the arc tube is used, the value is extremely low at about 12%. Empirically, it is said that 30% or more is visually preferable for this illuminance ratio, and as mentioned above, when using a metal halide lamp with a clear surface, the illuminance ratio becomes low and uneven illuminance occurs on the screen. There was a problem that it became extremely uncomfortable.

On the other hand, in order to eliminate the discomfort caused by uneven illuminance, a frost portion 1 is provided over the entire surface of the arc tube 101.
It is conceivable to form 21. Figure 9 shows an example of using an arc tube with a frosted outer surface.
As shown in the figure, about 1/2 to 1/4 of the light in the frost part is directly emitted from the light emitting part as straight light, and the remaining light is emitted from the frost part as light scattered around the straight light.

Therefore, when the arc tube with the frosted portion 121 formed on the entire surface of the arc tube except for the heat insulating film 106 is placed inside the reflector and irradiated onto the screen, the emitted light will be emitted from the reflector with a relatively large eccentricity. Approximately 1/2 to 1/4 of the straight light hits this portion and is reflected, reaching the periphery of the center of the screen. In addition, a small amount of scattered light reaches the center and periphery of each screen, and when the illuminance distribution along the line A-A' on the screen is measured, it is as shown by curve b in Figure 6. Become. This poses a problem in that although the illuminance ratio can be increased, the overall illuminance decreases, and the desired illuminance cannot be obtained even in the center, causing too much light to be scattered and wasted.

[0009]

[Problems to be Solved by the Invention] In view of the above, the present invention
This was developed to solve the problems with conventional metal halide lamp devices, and it is a high-quality optical system that does not cause uneven illuminance on the screen, has high screen illuminance, and can increase the illuminance ratio on the screen. The present invention aims to provide a metal halide lamp device for equipment.

0010

[Means for Solving the Problems] The present invention provides a reflector having a reflecting surface such as a paraboloid or an ellipsoid, and a front surface of the reflector so that the axis connecting the two electrodes substantially coincides with the central axis. In a metal halide lamp device comprising a metal halide lamp that does not use an outer tube, the metal halide lamp has a reflective and heat insulating film formed on the outer surface of the lamp around the electrode located on the opening side of the reflecting mirror, and a heat insulating film. A plurality of convex portions or concave portions are formed on the unformed outer surface of the lamp. The projection or recess formed on the outer surface of the lamp is characterized by comprising a plurality of projections or recesses.

[0011]

[Operation] Straight light from the light emitting part is focused in front of the reflector by the action of the convex lens of the protrusion formed on the clear surface of the outer surface of the lamp, and enters and is reflected by the reflector with a spread of a predetermined angle. Therefore, light effectively reaches the center of the screen and the periphery of the screen. Then, the screen illuminance and the illuminance ratio are increased, and the unevenness of illuminance is reduced.

[0012] Further, the straight light from the light emitting part is caused by the action of the concave lens formed in the clear surface of the outer surface of the lamp.
Since the light enters and is reflected by the reflecting mirror with a predetermined angle of spread without scattering, effective light reaches not only the center of the screen but also the periphery of the screen. Then, the illuminance around the screen increases, and the unevenness of illuminance decreases. Either way, you'll get a high-quality screen.

[0013]

Embodiment A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram showing an example of a metal halide lamp device. In the figure, 1 is a quartz arc tube with a pair of electrodes 2a and 2b sealed at both ends, and a rare gas and metal halide sealed inside. This is a short arc metal halide lamp. The arc tube consists of a light emitting part 1a having an elliptical cross section and sealing parts 1b formed at both ends of the light emitting part 1a.

Further, on the outer surface of the arc tube corresponding to the peripheral part of the electrode 2a located on the opening side 7a of the reflecting mirror 7, which will be described later, there is a light-reflective and heat-resistant material made of an alumina-silica mixture. A reflective and heat insulating film 3 is formed by coating. Furthermore,
The outer surface of the light emitting portion 1a of the electrode 2b located from the edge 3a of the heat insulating film to the bottom side 7b of the reflecting mirror 7 is a clear surface, and a protrusion 4 is formed on the clear surface.

[0015] In such an arc tube, wires are connected to the nickel lead 5 and the base 6, respectively, and a parabolic reflector made of hard glass with a cold mirror film coated on the inner surface surrounds the arc tube. 7 is attached so that its central axis substantially coincides with the axis of the arc tube, and one end of a lead wire is led out to the outside of the reflector and connected to a terminal 8 to constitute a metal halide lamp device.

When the metal halide lamp device constructed as described above is lit at a rating of 150W, the total luminous flux is 12,000l.
It exhibits light emitting characteristics of m, color rendering index Ra of 85, and color temperature of 7000 K, and has excellent characteristics as a lamp for optical devices.

When the image was projected onto the screen shown in FIG. 7 using a predetermined optical system, an average illuminance of 4000 lx was obtained. Further, when the illuminance distribution was measured along the line AA' of the screen, an illuminance characteristic like the curve c shown by the dashed-dotted line in FIG. 6 was obtained. Compared to the conventional curves a and b, the center illuminance is higher and the peripheral illuminance is also higher, so the illuminance ratio is approximately 40%.
As a result, a high-quality screen can be obtained.

The reason why such a high average illuminance and illuminance ratio can be obtained is considered to be as follows. That is, in the metal halide lamp according to the present invention, a plurality of protrusions 4, 4, 4, ... are formed on the clear surface of the outer surface of the arc tube, so that the straight light is emitted as shown in the optical path from the light emitting part in FIG. The protrusion formed on the tube surface acts as a convex lens, and the light is condensed in front of the parabolic reflector 7 and reaches the reflector as light that spreads within a certain angle, so it is effective almost at the center of the screen. The components that reach the area and the components that reach the periphery of the screen reach the screen. Therefore, there are fewer wasted components, the average illuminance is high, and a high screen illuminance with an illuminance ratio of 40% can be obtained.

On the other hand, in a conventional lamp in which a frosted portion is formed on the outer surface of the arc tube, as shown in FIG. This results in a reduction in the amount of light that effectively reaches the reflecting mirror. Therefore, as shown by curve b in FIG. 6, although the illuminance ratio is large, the overall illuminance decreases, and the desired illuminance cannot be obtained.

Next, a second embodiment will be explained based on FIG. 2. The same parts in the figure as in FIG. A light-reflective and heat-resistant reflective and heat-insulating film 3 made of an alumina-silica mixture is coated on the outer surface of the arc tube corresponding to the peripheral area of the electrode 2a located on the opening side 7a of the reflector 7. , the outer surface of the light emitting part 1a of the electrode 2b located from the edge 3a of the heat-retaining film to the bottom side 7b of the reflecting mirror is a clear surface, and a recess 1 is fitted in the clear surface.
0 is formed.

When the image was projected onto the screen shown in FIG. 7 using a predetermined optical system in the same manner as in the first embodiment, 4000 l of light was projected onto the screen shown in FIG.
The average illuminance of x was obtained. Further, when the illuminance distribution was measured along the line AA' of the screen, an illuminance characteristic similar to the curve c shown by the dashed-dotted line in FIG. 6 was obtained. Compared to curves a and b of the conventional example, this has a higher center illuminance and a higher peripheral illuminance, so the illuminance ratio is about 40%, and a high quality and good screen can be obtained.

The reason why such a high average illuminance and illuminance ratio can be obtained is considered to be as follows. That is, the clear surface of the outer surface of the arc tube has a plurality of dents 10, 10,
As shown in the optical path from the light emitting part in Figure 4, the depression formed on the surface of the arc tube acts as a concave lens, and the light has a certain spread and travels straight only in a certain angular range and is scattered. reaching the reflector without any problems. Although reflected by the reflecting mirror, there are many effective light components that reach not only the center of the screen but also the periphery of the screen, resulting in a bright screen not only at the center but also at the periphery. This is because compared to conventional frosted lamps, there is less scattered light and more effective light.

In the above embodiments, the projections or recesses formed on the outer surface of the arc tube are described as protrusions or recesses, but they may be formed as long as they act as a convex lens or a concave lens. It may also be formed into a shape.

[0024]

Effects of the Invention As is clear from the above description, the metal halide lamp device according to the present invention has a relatively simple structure and can be used without uneven illuminance on the optical screen.
It is possible to obtain a high-quality metal halide lamp device for an optical device that can provide high screen illuminance and increase the illuminance ratio.

[Brief explanation of drawings]

FIG. 1: A first metal halide lamp device according to the present invention.
FIG. 3 is a partially cutaway side view of the embodiment.

[Fig. 2] A second metal halide lamp device according to the present invention.
FIG. 3 is a partially cutaway side view of the embodiment.

FIG. 3 is an explanatory diagram showing the path of light emitted from the arc tube of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing the path of light emitted from the arc tube of the second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a path of light emitted from a conventional arc tube.

FIG. 6 is a diagram showing the illuminance distribution when projected onto a screen.

FIG. 7 shows a screen used to measure average illuminance and illuminance ratio.

FIG. 8 is a partially cutaway side view showing a conventional metal halide lamp device.

FIG. 9 is a side view of a conventional lamp in which a frost portion is formed on the outer surface of the arc tube.

[Explanation of symbols]

1 Arc tube 3. Reflective and heat-retaining film 4 Protrusion 7 Reflector 10 Dent

Claims (3)

[Claims] 1. A reflecting mirror having a reflecting surface such as a paraboloid or an elliptical surface, and an outer surface disposed in front of the reflecting mirror so that the axis connecting both electrodes substantially coincides with the central axis of the reflecting mirror. In a metal halide lamp device comprising a metal halide lamp that does not use a tube, the metal halide lamp has a reflective and heat insulating film formed on the outer surface of the lamp around the electrode located on the opening side of the reflecting mirror, and the heat insulating film A metal halide lamp device in which a plurality of convex portions or concave portions are formed on the outer surface of the lamp. 2. The convex portion formed on the outer surface of the lamp is
The metal halide lamp device according to claim 1, wherein a plurality of protrusions are formed. 3. The recess formed on the outer surface of the lamp is
The metal halide lamp device according to claim 1, wherein a plurality of depressions are formed.