JPH0636747A - Light source device - Google Patents

Abstract

PURPOSE:To form a high-quality screen excellent in color reproducibility and luminescence efficiency and having no color irregularity. CONSTITUTION:A dielectric multi-layer film 9b made of layers of titanium dioxide or tantalum pentaoxide and silicon dioxide in turn is formed on a glass substrate 9a to obtain a reflecting mirror 9 so that the dielectric multi-layer film 9b is made thicker toward the outer periphery side. A metal halide lamp containing dysprosium iodide-neodymium iodide-cesium iodide as an emissive material is arranged approximately near the focal point position of the reflecting mirror 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device, and more particularly to a light source device equipped with a short arc metal halide lamp and a reflecting mirror suitable as a light source device for a liquid crystal projector.

[0002]

2. Description of the Related Art In recent years, light source devices for liquid crystal projectors, which are rapidly becoming popular, are required to have good color reproducibility and luminous efficiency. However, in the spectral distribution of the halogen lamp used in the conventional light source device, the blue region component light emission does not reach a desired value. Therefore, in order to increase the luminous efficiency, RG
A method of capturing even unnecessary yellow and orange components on B as light for projection has been conventionally used. However, as a result, the color temperature of the image on the screen becomes as low as 4000 K, which gives rise to the problem that only a very low quality image can be obtained.

However, such a problem does not occur in the light source device including the combination of the short arc metal halide lamp containing a rare earth metal halide and the reflecting mirror. This is because the rare earth metal halide contributes to the improvement of the color reproducibility and the luminous efficiency. Here, the short arc metal halide lamp is, for example, a metal halide lamp in which a halide of a rare earth metal such as dysprosium or neodymium is enclosed in a discharge vessel having a short arc (for example, an internal volume of about 0.4 cc). For example, equipped with this lamp, arc length is about 5mm, rated power is 150W
In the light source device of No. 2, the main light emission distribution of the selected inclusion is good, the blue light emission is sufficient, and the desired RGB is obtained, and the color temperature of about 8000K can be obtained. Are known.

FIG. 5 shows an optical portion of a single plate type liquid crystal projector provided with a light source device composed of the above short arc metal halide lamp and a reflecting mirror. In the figure, arc tube 11
Is made of metal halide lamps. Reflector 19
Is a conventionally known dichroic parabolic mirror, and has a uniform thickness (λ / 2 or λ / 4; provided that λ / 2 or λ / 4; formed on the glass substrate 19a and its inner surface by a vacuum deposition method or the like.
Is the emission wavelength of the arc tube 11)
And consists of. The dielectric multilayer film 19b, which constitutes the reflecting surface of the reflecting mirror 19, is composed of alternating layers of titanium dioxide and silicon dioxide. Therefore, of the light from the arc tube 11, mainly infrared light is directed backward. Transmits and reflects visible light.

Reference numeral 13 is a UV-IR cut filter, 14
Is an incident side polarization plate, 15 is a liquid crystal panel, 16 is an emission side polarization plate, and 17 is a projection lens. The arrows attached to the polarizing plates 14 and 16 represent the polarization axis (transmission axis) PX. The reflecting mirror 19 collects the light emitted from the arc tube 11,
The light is transmitted through the V-IR cut filter 13, the incident side polarization plate 14, the liquid crystal panel 15, the emission side polarization plate 16 and the projection lens 17 and projected on a screen (not shown) to obtain a substantially good light distribution (illuminance distribution). Form an image.

Regarding the reflecting surface of the reflecting mirror 19 in FIG. 5, incident angles θA, θB and θ at positions A, B and C of the reflecting surface are shown in FIG.
Indicates C. Incident angle θ at each position A, B and C of the light beam emitted from the light emitting point 11a corresponding to the position of the arc tube 11.
A (= 38 °), θB (= 51 °), and θC (= 60 °) are closer to the outer peripheral side of the reflecting surface (that is, position A,
It becomes larger in the order of B and C).

7 (a), (b) and (c), the above-mentioned position A,
The relationship between the spectral transmittances of the P-wave component and the S-wave component in B and C (FIG. 6) and their average value (P + S) / 2 and the wavelength is shown. Since the incident angle increases in the order of the positions A, B, and C, the average value (P + S) / 2 itself shifts to the short wavelength side, and the separation width between the P wave component and the S wave component increases. As a result, it can be seen that as the incident angle becomes larger, the reflected light shifts to the shorter wavelength side, and the P wave component of R in the reflected light decreases extremely. This is because the dielectric multilayer film 19b has a property of reflecting or transmitting light in a specific wavelength range according to the controlled optical film thickness of each layer, and the optical interference action of the dielectric multilayer film 19b is Multilayer film 19b
This is because it depends on the angle of incidence on.

FIG. 8 shows the incident side polarization plate 14 in FIG. 5 as viewed from the liquid crystal panel 15 side. The range indicated by the alternate long and short dash line indicates the range 19c that is irradiated by the reflecting mirror 19 (FIG. 5). The incident side polarization plate 14 has its polarization direction (polarization axis PX direction) set to the optical axis A of the liquid crystal panel 15.
It is tilted 45 ° with respect to X. The polarization axis PX in the range where the light from the reflecting mirror 19 is incident on the incident side polarization plate 14
In the diagonal of the direction (upper right part and lower left part of range 19c),
Since the P wave component PW of the light from the reflecting mirror 19 becomes the transmitted light, the amount of R light in the transmitted light of the incident side polarization plate 14 is insufficient due to the above reason. As a result, the colors G and B are relatively strong in the diagonal direction of the polarization axis PX. At other diagonals (the upper left portion and the lower right portion of the range 19c), the S wave component SW of the light from the reflecting mirror 19 becomes the transmitted light, so that the R light amount does not become insufficient.

FIG. 9 shows a screen screen 18 formed by the optical system shown in FIG. Corresponding to the incident side polarization plate 14 shown in FIG. 8, the upper left portion A1 and the lower right portion A2 of the screen screen 18 lack the light amount of R in RGB. As a result, G and B become relatively strong,
Color unevenness occurs.

As described above, the S wave component and the P wave component of the light emitted from the short arc metal halide lamp are
Since polarized light is received by the dielectric multilayer film 19b forming the reflecting surface of the reflecting mirror 19, the light is transmitted through the two polarizing plates 14 and 16, so that both diagonals (four corners) of the screen screen 14 are blue and green. The image will appear in the light of the area.
Therefore, although the screen is almost good and formed in good quality, the image quality cannot be said to be high quality.

In order to prevent the occurrence of color unevenness due to the dielectric multilayer film 19b, Japanese Utility Model Publication No. 2-15213 discloses a reflector for a halogen lamp having a reflection mirror made of a dielectric multilayer film on its inner surface. A reflector for a halogen lamp has been proposed in which a neck portion having a small incident angle from a light source has a thin film thickness and a flange portion having a large incident angle has a thick film thickness. In this reflector, by increasing the thickness of the dielectric multilayer film of the reflection mirror of the halogen lamp as it goes from the bottom of the reflecting surface to the front,
The wavelength shift due to the incident angle dependence is prevented, so that the color temperature is made substantially equal in the central portion and the peripheral portion of the spotlight.

[0012]

A light source device comprising a combination of a short arc metal halide lamp containing a rare earth metal halide and a reflecting mirror is excellent in color reproducibility and luminous efficiency as described above, but it is not a metal halide lamp. The amount of UV (ultraviolet) is much higher than that of halogen lamps. Therefore, when the dielectric multilayer film is composed of ZnS and MgF ₂ as in Japanese Utility Model Publication No. 2-15213, the dielectric multilayer film is significantly deteriorated. Therefore, use the dielectric multilayer film having such a structure. I can't.

The present invention has been made in view of these points, and an object thereof is to provide a light source device which is excellent in color reproducibility and light emission efficiency and which can form a high-quality screen screen without color unevenness. To do.

[0014]

In order to achieve the above object, the light source device of the present invention comprises a dielectric multilayer film comprising alternating layers of titanium dioxide and silicon dioxide on a glass substrate. A reflecting mirror formed so as to become thicker toward the outer peripheral side thereof, and arranged near the focal position of the reflecting mirror,
And a metal halide lamp containing a rare earth metal halide as a luminescent material.

Further, in the light source device of the present invention, the dielectric multi-layered film composed of the alternating layers of tantalum pentoxide and silicon dioxide is formed on the glass substrate so that the outer peripheral side of the dielectric multi-layered film becomes thicker. And a metal halide lamp that is disposed near the focal point of the reflector and that contains a rare earth metal halide as a light emitting material.

[0016]

With this structure, since the dielectric multilayer film becomes thicker toward the outer peripheral side, the wavelength of the reflected light shifts even if the incident angle of the light of the metal halide lamp on the dielectric multilayer film changes. Therefore, it is possible to obtain illumination light without color unevenness.

[0017]

Embodiments of the light source device of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a light source device of the present embodiment, and FIG. 2 is a perspective view showing a part of the present embodiment by cutting away. This embodiment is a light source device for a liquid crystal projector, and mainly comprises an arc tube 1 which is a short arc metal halide lamp and a reflecting mirror 9.

The arc tube 1 is a short arc discharge container made of quartz glass (internal volume 0.4 cc, maximum outer diameter φ11.0 mm, maximum inner diameter φ8.7 mm) 1a. Cium-neodymium iodide-cesium iodide (Dy
I ₃ -NdI ₃ -CsI, weight ratio 8: 4: 5) 0.8 mg
And Ar (argon) 250 × 10 ² Pa as starting auxiliary gas
(Pascal) and Hg (mercury) as buffer gas 10 mg
It is a metal halide lamp with and enclosed. As shown in FIG. 2, tungsten electrodes 2a and 2b are inserted into the light emitting portion 1b from both ends of the discharge vessel 1a via molybdenum foils 3a and 3b, respectively. The molybdenum foil 3
a and 3b have both power supply and airtight sealing,
Molybdenum wires 4a and 4b connected to the molybdenum foils 3a and 3b are led out from the discharge vessel 1a. The distance between electrodes (ground length) is about 5.0 mm. A reflective and heat retaining film 5 mainly composed of a mixture of alumina and silica is applied to the peripheral portions of the two electrodes 2a and 2b.

The reflecting mirror 9 is a conventionally known dichroic parabolic mirror, and as shown in FIG. 1, it is formed on a glass substrate 9a made of hard glass and its inner surface by a vacuum deposition method or the like. And a dielectric multilayer film 9b. The dielectric multilayer film 9b is composed of alternating layers (about 30 to 50 layers) of titanium dioxide (TiO ₂ ) and silicon dioxide (SiO ₂ ) and constitutes the reflecting surface of the reflecting mirror 9. still,
This alternating layer is formed by laminating a single composition film having a predetermined thickness, similarly to the alternating layer of ZnS and MgF ₂ disclosed in Japanese Utility Model Publication No. 2-15213. In addition, the reflecting mirror 9
Has an effective diameter of 100 mm and a focal length of 13 mm.
It is a paraboloid of zero-order function. It should be noted that this paraboloid may be made up of one or more combinations of multidimensional functions including paraboloids, spheres, and ellipses. Further, as shown in FIG. 2, the parabolic surface is positioned so as to be substantially coaxial with the tube axis of the arc tube 1, and the light emitting section 1b is positioned substantially near the focal position of the reflecting mirror 9. The reflecting mirror 9 is attached.

The thickness of the dielectric multilayer film 9b is so formed that it becomes thicker from the marginal effective surface LA at the bottom to the flange surface FA shown in FIG. That is, with respect to the dielectric multilayer film 9b, the film thickness is smaller in the portion where the incident angle from the arc tube 1 is smaller, and is larger in the portion where the incident angle is larger. Further, since the dielectric multilayer film 9b is composed of TiO ₂ and SiO ₂ as described above, the deterioration of the dielectric multilayer film is small even when used in combination with a metal halide lamp that emits a large amount of UV, and the dielectric multilayer film is a film. It is possible to take measures against color unevenness due to the thickness.

In order to supply electric power to the electrodes 2a and 2b,
A terminal plate 10 connected to the tungsten wire 4 and the wire 7 and a base 8 connected to the tungsten wire 4b are attached to a reflecting mirror 9. Auxiliary conductor wire 6
Is a trigger electrode for starting lighting.

It is to be noted that a predetermined lamp power (that is, a frequency of 400H) is applied to the electrodes 2a and 2b through the base 8 and the terminal plate 10.
(Rated 150W with a rectangular wave of z, but including the starting circuit)
, The average color rendering index (Ra) is 9
0, the color temperature (TC) was 8000 K, and the light having the emission spectrum of FIG. 4 could be obtained. From this, it was found that the present example exhibits excellent color characteristics as a video lamp device. Therefore, the light source device and the liquid crystal of the present embodiment,
By using an optical component such as a dichroic mirror lens, it is possible to project a high-quality image without color unevenness for a video movie onto a large screen.

Further, although the lamp power of 150 W is used in this embodiment, any metal halide lamp of 50 W or more can be suitably used. Incidentally, in forming a liquid crystal projector using this embodiment, a polarizing plate having an inclination angle of 45 ° with respect to the optical axis AX of the polarization axis PX may be used as in the conventional example shown in FIG. °, 180
Those of ° may be used.

Next, the relationship between the spectral transmittances of the P wave component and the S wave component at the positions A, B and C of the reflecting mirror 9 in FIG. 1 and their average value (P + S) / 2 and the wavelength will be described. , As in the case of the conventional example of FIG. 7,
Each is shown in (c). The incident angle at position A is 38 °, the incident angle at position B is 51 °, and the incident angle at position C is 60 °. The film thickness ratio between the positions A, B, and C is 1.00: 1.05: 1.10. Further, the position B in FIG. 1 is the effective limit surface LA at the bottom of the reflecting mirror 9 and the flange surface F.
The position is almost in the center with A. From the spectral characteristics of FIG. 3, in the present embodiment, even if the incident angle increases in the order of positions A, B, and C, there is almost no shift of the average value (P + S) / 2 itself to the short wavelength side. It can be seen that the reflected light does not shift to the short wavelength side even if it becomes large, and the P wave component of R in the reflected light does not extremely decrease.

The dielectric multilayer film 9b is made of at least Ti.
Any multi-layer film containing O ₂ and SiO ₂ may be used, but the amount of change in the film thickness depends on the polarization axis PX and the incident angle dependency on the dielectric multi-layer film 9b, and the wavelength separation and the separation action between P wave and S wave. Therefore, it is necessary to adjust the color unevenness on the screen of the liquid crystal projector as in the present embodiment.

As described above, according to the configuration of this embodiment,
Screen screen 18 (FIG. 9) resulting from the separating action of P wave and S wave caused by the polarization axis PX of the polarizing plates used in combination (FIG. 8) and the wavelength shift due to the incident angle dependence on the reflecting mirror 9. The level of color unevenness can be improved. That is, the dielectric multilayer film 9b forming the reflection surface is made of Ti.
The dielectric multilayer film 9 is composed of O2 and SiO2.
The film distribution of b is changed to the dielectric multilayer film 9b in the order of positions A, B, and C.
By increasing the thickness toward the outer periphery of the reflector, the reflection angle is increased and the reflection characteristics of the reflector suitable for the metal halide lamp are obtained. This prevents the wavelength shift to the short wavelength side and reduces the shortage of the amount of R light at the diagonal part of the polarizing plate.
Color unevenness on the screen screen can be improved.

In the above embodiment, the dielectric multilayer film 9b is composed of alternating layers of titanium dioxide and silicon dioxide, but the dielectric multilayer film is composed of alternating layers of tantalum pentoxide and silicon dioxide. Well, even in that case, the same effect can be obtained.

[0028]

As described above, in the light source device of the present invention, the dielectric multilayer film on the glass substrate that constitutes the reflecting mirror is composed of alternating layers of titanium dioxide or tantalum pentoxide and silicon dioxide. In addition, it is possible to combine with a metal halide lamp containing a rare earth metal halide as a luminescent substance, and as a result, excellent color reproducibility and luminous efficiency can be obtained, and the dielectric multilayer film becomes thicker toward the outer peripheral side. Since it is formed, it is possible to realize a light source device capable of forming a high-quality screen screen without color unevenness.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which a part of the embodiment of the present invention is cut away.

3A and 3B are positions A and B of reflecting mirrors constituting an embodiment of the present invention.
The figure which shows the spectral transmittance in C and C.

FIG. 4 is a spectral distribution chart showing an emission spectrum of light obtained according to an example of the present invention.

FIG. 5 is a perspective view showing an optical portion of a single plate type liquid crystal projector to which a conventional example is applied.

FIG. 6 shows positions A, B, C of a reflecting mirror 19 which constitutes a conventional example.
FIG. 6 is a diagram showing incident angles θA, θB, and θC of light rays from the light emitting source 11a in FIG.

FIG. 7 is a diagram showing spectral transmittances at positions A, B and C of a reflecting mirror 19 which constitutes a conventional example.

FIG. 8 is a diagram for explaining the relationship between the polarization axis PX and the P wave component PW of the incident side polarization plate 14 applied to the conventional example.

9 is a screen screen 18 by the optical system shown in FIG.
FIG. 6 is a diagram showing an insufficient amount of R light in the image formed above.

[Explanation of symbols]

 1 arc tube 9 reflecting mirror 9a glass substrate 9b dielectric multilayer film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Kikuzuki, Koji Kikuzuki, 380, Jyuji, Kashiwa, Chiba Prefecture Okamoto Glass Co., Ltd. Saitama Factory

Claims (2)

[Claims] 1. A reflecting mirror formed by forming a dielectric multi-layered film composed of alternating layers of titanium dioxide and silicon dioxide on a glass substrate so that the outer peripheral side of the dielectric multi-layered film becomes thicker. A light source device, comprising: a metal halide lamp disposed near a focal point of a reflecting mirror and containing a rare earth metal halide as a light emitting material. 2. A reflecting mirror formed by forming a dielectric multi-layered film, which is composed of alternating layers of tantalum pentoxide and silicon dioxide, on a glass substrate so that the outer peripheral side of the dielectric multi-layered film becomes thicker. A light source device, comprising: a metal halide lamp disposed near the focal position of the reflecting mirror and containing a rare earth metal halide as a light emitting material.