JPH06132012A - Metal halide lamp and light projecting device using same - Google Patents

Abstract

PURPOSE:To provide a metal halide lamp that discrepancy of luminous color between the central part and the peripheral part of a light emitting tube is reduced so that color unevenness between the central part and the peripheral part of a screen is reduced, as well as a light projecting device using it as a light source. CONSTITUTION:When the elclosed mol number of a dysprosium halide enclosed in a light emitting tube 20 is designated as ml, and the enclosed mol number of neodymium halide as m2, it is characterized in that these elclosed mol numbers are selected so as to satisfy m1/m2<1. Accordingly, even if any color temperature discrepancy takes place between the central part of the circumferential direction and the peripheral part in an arc in the light emitting tube 20 due to dysprosium halide, neodymium halide reduces the color temperature discrepancy around the peripheral part so as to enhance visuality on a screen.

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 and a light projecting device which uses the lamp as a light source and reflects light emitted from the light source by a reflector.

[0002]

2. Description of the Related Art A typical application of a short arc metal halide lamp is used as a light source of a translucent device typified by a color liquid crystal projector or the like.

The basic principle of the color liquid crystal projector will be described with reference to FIG.
The projector 1 comprises a lamp 1 which is a light source and a reflector 2 which reflects light emitted from the light source,
It has a condenser lens 3 for condensing the reflected light reflected by the reflector 2.

The light radiated forward from the condenser lens 3 is reflected by a dichroic mirror (wavelength selective reflecting mirror) 4 which reflects blue light, and this blue light is reflected by a mirror 5 and liquid crystal. Illuminate the panel (LCD) 6,
The image on the liquid crystal panel 6 is colored blue and projected on the screen 10 via the other dichroic mirrors 7 and 8 and the projection lens 9.

Of the light projected from the condenser lens 3, the red and green lights pass through the dichroic mirror 4 which reflects the blue light, and the red light is reflected by the other dichroic mirror 11. LCD panel 1
2, the image on the liquid crystal panel 12 is colored red, and the red image is reflected by the dichroic mirror 7 and transmitted through the other dichroic mirrors 8 and the projection lens 9
The image is projected on the screen 10 via.

Further, the green light transmitted through the dichroic mirror 11 for reflecting the red light irradiates the liquid crystal panel 13 to color the image on the liquid crystal panel 13 green, and the green image is reflected by the mirror 14 and the dichroic mirror. It is reflected by 8 and projected on the screen 10 via the projection lens 9.

Therefore, by controlling the images of the three liquid crystal panels 6, 12 and 13, images of three colors are superimposed and projected on the front surface of the screen 10, and a color image is displayed.

As a light source for such a color liquid crystal projector, a shape close to that of a point light source, a large amount of light can be obtained for low power consumption, and red, blue and green components are efficiently radiated, and a mirror or lens is used. Even when used in combination with an optical system such as a lamp, it is necessary to have a lamp that can send the abundant three primary colors of light to the necessary area and can satisfy the conditions such as less heat generation. A short arc metal halide lamp is suitable as a filling lamp. FIG. 1 shows the structure of a light projecting device 50 in which this type of short arc metal halide lamp 1 and a reflector 2 are combined.

In the figure, reference numeral 20 denotes an arc tube of the short arc metal halide lamp 1. The arc tube 20 is made of quartz glass, and electrodes 21 and 21 are sealed at both ends,
The pair of electrodes 21, 21 are connected to the metal foil conductors 23, 23 sealed to the sealing portions 22, 22. One of the metal foil conductors 23 is electrically connected to a cap 24 attached to the end portion via an external lead wire (not shown), and the other metal foil conductor 23 is connected to an external lead wire 25. Has been done. The arc tube 20 contains mercury as a buffer metal, a metal halide as a light emitting metal, and a rare gas such as argon.

Such a lamp 1 is attached to a reflector 2. The reflector 2 is made of glass or metal and has a TiO ₂ -excellent reflective property on the inner surface of the rotating curved surface.
It has a reflecting surface 31 made of a vapor deposition film such as SiO ₂ . A front light projecting portion of the reflector 2, that is, an opening portion is formed with a diameter of about 90 to 130 mm, and a support cylinder portion 32 is provided on the top of the back portion. The base 24 of the lamp 1 is fixed to the support cylinder 32 with an adhesive 33 such as insulating cement. This allows the lamp 1
The lamp axis O ₁ -O ₁ of the lamp 1 substantially coincides with the central axis of the reflector 2, that is, the optical axis O ₂ -O _2.
Are attached to the reflector 2. In addition, the reflector 2
A lead-in hole 34 is formed in the hole, and the outer lead wire 25 of the lamp 1 penetrates through the lead-in hole 34 and is guided to the back side.

The lamp 1 of such a light projecting device 30 has an arc length, that is, an interelectrode distance L of 12 mm or less, preferably 4 to 7 mm, and 150 W to 250 W of electric power is supplied at a commercial frequency during lighting. As a result, the pipe wall load is 20 to 1
00W / cm ² Used under heavy load conditions.

Examples of the metal halide enclosed in the arc tube 20 of the short arc metal halide lamp 1 include rare earth metals such as dysprosium Dy, neodymium Nd, indium In, thallium Tl, holmium Ho, thulium Tm, scandium Sc, and cesium Cs. Is used. These rare earth halides emit light over the entire visible light region, and therefore have good color rendering and light
This is because it is suitable for efficiently emitting the primary colors.

For example, JP-A-3-95849 discloses a metal halide lamp in which a metal halide containing at least dysprosium halide and neodymium halide is enclosed in the arc tube.
A lamp has been proposed which has a color temperature of 7,000 to 9,500 K and can obtain a continuous emission spectrum distribution over the entire visible light range.

In the case of the above publication, when the number of moles of dysprosium halide enclosed is m1 and the number of moles of neodymium halide enclosed is m2, the mole ratios of these inclusions are calculated as follows: The number is relatively increased to 0≤m2 / m1≤1.

[0015]

However, in the conventional short arc metal halide lamp as described above, there is a difference in emission color between the central portion of the arc tube and the peripheral portion near the bulb wall, and variations in emission color occur. Occurs.
This is because a large amount of dysprosium halide enclosed in the arc tube has a high color temperature in the radial center part of the arc in the arc tube and a higher color temperature in the peripheral part (a part near the bulb wall). It is presumed that this is due to the lowering of.

When such a lamp 1 is used as a light source in the color liquid crystal projector shown in FIG. 2, there is a drawback in that color unevenness occurs in the central portion and the peripheral portion of the screen 10.

The present invention has been made in view of the above circumstances, and an object of the present invention is to eliminate the difference in the emission color between the central portion and the peripheral portion of the arc tube and to eliminate the difference from the central portion of the screen. An object of the present invention is to provide a metal halide lamp that does not cause color unevenness in the periphery and a light projecting device using the same.

[0018]

According to the present invention, the number of moles of dysprosium halide enclosed in an arc tube is m1,
When the enclosed mole number of neodymium halide is m2,
It is characterized in that the enclosed molar ratio is m1 / m2 <1.

[0019]

In the present invention, the number of moles m2 of neodymium halide enclosed is relatively larger than that of the conventional one, and the mole ratio of the number of moles m2 of neodymium halide to the number of moles m1 of dysprosium halide is m1 / m2 < Therefore, even if a color temperature difference occurs between the radial center and the peripheral part (the part near the bulb wall) in the arc in the arc tube due to dysprosium halide, neodymium halide causes such a difference in color temperature. As a result, the neodymium halide supplements the color temperature of the peripheral portion, thus improving the visual impression.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

This embodiment is based on FIGS. 1 and 2 described above.
The present invention is applied to the color liquid crystal projector shown in FIG. 2 and the contents already explained in the above drawings are duplicated, and the explanation thereof will be omitted.

The short arc metal halide lamp 1 shown in FIG. 1 has a rated input of 250 W, and the light emitting portion of the arc tube 20 is a substantially elliptical rotator made of quartz glass having a thickness of 1.4 mm. Is about 15 mm and the minor axis is about 10
mm, resulting in an internal surface area of approximately 4.7 cm ² The internal volume is approximately 1.0 CC. The electrodes 21, 21 sealed at both ends of the arc tube 20 are 2
% Tungsten electrode having a length of 10 mm and a thickness of 0.7 mm, which is made of a tungsten-thorium alloy containing% thorium, has an electrode coil 212 in which a tungsten wire having a wire diameter of 0.5 mm is tightly wound 3 turns. , These electrodes 21, 21
The distance L between the electrodes is 6 mm.

The metal foil conductors 23, 23 sealed to the sealing portions 22, 22 are Mo foils, and have a width of 3 mm and a thickness of 30.
It is said to be μm. The outer lead wire 25 is made of a 0.8 mm diameter Mo metal rod. A rough surface portion may be formed on the outer surface of the arc tube 20 by frosting, if necessary.

In the arc tube 20, 22 mg of mercury, metal halides such as iodides and bromides of Dy, Nd, Cs, In and Tl, and 3 as a rare gas of Ar are contained.
00 Torr is included. Dy, Nd, Cs, In, T
l iodide and bromide specifically of, DyBr ₃ is 0.5mg, NdBr ₃ is 1.0 mg, CsI is 0.2 mg,
InBr is 0.2 mg and TlBr is 0.2 mg, and DyBr ₃ / NdBr ₃ is 0.5 by weight.

In such a lamp 1, the base 24 and the external lead wire 25 are connected to a commercial power source, and 150 W to 2 W during lighting.
By supplying 50 W of power, the pipe wall load is 20-
100 W / cm ² Used under heavy load conditions.

In such a short arc metal halide lamp, since the encapsulation ratio of DyBr ₃ and NdBr ₃ is 1.0 or less, for example 0.5, the color temperature difference between the central part and the peripheral part of the arc is reduced. Was done. For this reason, color unevenness in the central portion and the peripheral portion is eliminated on the screen 10, and a screen having a good visual impression can be obtained.

FIG. 3 shows the molar ratio of the dysprosium halide encapsulated m1 (however, halogen is iodine or bromine) to the neodymium halide encapsulated m2 (however, halogen is iodine or bromine). m2) and the relationship between the chromaticity unevenness between the central part and the peripheral part on the screen.

From the characteristics shown in FIG. 3, it is understood that the effect of dysprosium halide becomes more pronounced and the color unevenness becomes larger as the inclusion ratio (m2) of neodymium halide is reduced. Since the limit of color unevenness is set to less than 5%, it is confirmed that the ratio of neodymium halide should be increased to the range of m1 / m2 <1 in order to satisfy this limit. It

As described above, even if the dysprosium halide causes a difference in color temperature between the central portion and the peripheral portion (the portion near the bulb wall) in the radial direction in the arc in the arc tube 20, the neodymium halide is generated. It is presumed that such a color temperature difference is small, and thus the neodymium halide reduces the color temperature difference in the peripheral portion.

As in the above-mentioned embodiment, in the lamp 1 used for lighting with a high tube wall load, there is a concern that cracks may occur in the sealing portion 22. As one of measures for preventing cracks from occurring in the sealing portion 22, the distance from the inner surface of the arc tube to the metal foil conductor 23 sealed in the sealing portion 22 (the grip depth of the electrode shaft 211) a For a lamp having an inter-electrode distance L of 15 mm or less, it is preferable to limit the range to 1 to 5 mm.

That is, if the distance a from the inner surface of the arc tube 20 to the metal foil conductor 23 is set to 1 ≦ a ≦ 5, the electrode shaft 21
It is possible to obtain a sufficient initial strength as the sealing strength of No. 1 and to prevent the occurrence of cracks due to the intrusion of a metal halide and the occurrence of cracks due to thermal strain.

As described in the above embodiment, the present invention is more visible when at least one of indium halide, thallium halide and lithium halide is enclosed in addition to dysprosium halide and neodymium halide. A well-balanced emission spectrum distribution can be obtained over the entire light range.

[0033]

As described above, according to the present invention, even if a color temperature difference occurs between the central portion and the peripheral portion in the radial direction in the arc in the arc tube due to the dysprosium halide, such a neodymium halide causes such a difference. Since the difference in color temperature is small, neodymium halide reduces the difference in color temperature in the peripheral portion, so that the difference in emission color between the central portion and the peripheral portion of the arc tube can be reduced. Therefore, in the case of the light projecting device, it is possible to reduce color unevenness between the central portion and the peripheral portion on the illuminated surface such as a screen.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a light projecting device including a metal halide lamp and a reflector.

FIG. 2 is an explanatory diagram showing the principle of a color liquid crystal projector.

FIG. 3 is a characteristic diagram showing the relationship between the inclusion molar ratio of dysprosium halide and neodymium halide and the color unevenness on the screen.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal halide lamp 2 ... Reflector 4, 7, 8, 11 ... Dichroic mirror 6, 12, 13 ... Liquid crystal panel, 10 ... Screen, 20 ... Arc tube 21 ... Electrode 2
2 ... Sealing part 23 ... Metal foil conductor 24 ... Base 2
5 ... External lead wire

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Tanaka 1-4-2 Mita, Minato-ku, Tokyo Toshiba Lighting & Technology Corporation

Claims (4)

[Claims] 1. A metal halide lamp in which electrodes are sealed at both ends of an arc tube and mercury, at least a metal halide of at least dysprosium halide and neodymium halide, and a rare gas are enclosed in the arc tube. When the number of moles of dysprosium halide enclosed in the arc tube is m1 and the number of moles of neodymium halide enclosed is m2, the metal mole ratio of these enclosures is m1 / m2 <1. . 2. The metal halide according to claim 1, wherein at least one of indium halide, thallium halide and lithium halide is enclosed in addition to the dysprosium halide and neodymium halide. Metal halide lamp. 3. A metal halide lamp in which electrodes are sealed at both ends of the arc tube, and mercury, at least a metal halide of at least dysprosium halide and neodymium halide, and a rare gas are sealed in the arc tube. In a projector having a reflector that reflects the light emitted from the lamp, the number of moles of dysprosium halide enclosed in the arc tube of the metal halide lamp is m1, and the number of moles of neodymium halide is m2. In this case, the floodlighting device is characterized in that the enclosed molar ratio is m1 / m2 <1. 4. The metal halide according to claim 3, wherein at least one of indium halide, thallium halide and lithium halide is enclosed in addition to the dysprosium halide and neodymium halide as the metal halide. Floodlight device.