JPH1186603A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination optical device which is excellent in uniformity of illuminance in an irradiation area, has high utilization efficiency of light from a light source lamp, and has a compact configuration. Provided is an optical device capable of suppressing a temperature rise in a connection portion between a foil and a lead bar in a sealing portion of a light source lamp. SOLUTION: A short arc type light source lamp 10 having sealing portions 11 and 12 at both ends, a concave reflecting mirror 20 arranged so that an optical direction and an optical axis of the light source lamp 10 coincide with each other, and a concave reflecting surface A first lens plate 30 having a plurality of lens elements 30A disposed in the optical path of the reflected light from the mirror 20, and the first lens plate forming an integrator optical system together with the first lens plate 30 An optical device comprising 30 lens elements 30A and a second lens plate 40 having a plurality of corresponding lens elements 40A, wherein a through hole 31 is formed at the center of the first lens plate 30. A plurality of lens elements 3 are provided around the through hole 31.
0A is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device, and more particularly, to an optical device having excellent uniformity of illuminance,
D (Digital Micro Mirror De
The present invention relates to an optical device that can be suitably used for illuminating an image display element such as a video display device.

[0002]

2. Description of the Related Art In recent years, a device (projection type liquid crystal projector) for enlarging and projecting an image formed on a liquid crystal display element on a screen has been proposed. In such an image projection device, it is necessary to illuminate a liquid crystal display element on which an image is formed. The illumination optical device is required to have uniform illuminance in the irradiated area.

As an optical device having good uniformity of illuminance in a region to be irradiated, an optical device equipped with an integrator optical system as shown in FIG. 1 has been introduced (see US Pat. No. 2,186,123). The optical device shown in FIG. 1 includes a short arc type light source lamp 1 having sealing portions at both ends, a parabolic mirror 2 arranged so that an arc direction of the light source lamp 1 and an optical axis L coincide with each other. A first lens plate 3 disposed on a plane perpendicular to the optical axis L on the optical path of the reflected light from the parabolic mirror 2, and a first lens plate 3 together with the first lens plate 3 to form an integrator optical system. 2 lens plates 4
And In the figure, 5 is an ultraviolet cut filter, 6 is a condenser lens, and 7 is an irradiation area (for example, a liquid crystal display element surface). As shown in FIG. 2, the first lens plate 3 constituting the integrator optical system is configured by arranging a plurality of (for example, 20) rectangular lens elements 3A. Further, the second lens plate 4 includes a plurality of lens elements 4A corresponding to each of the plurality of lens elements 3A (that is, located at the focal point of each of the plurality of lens elements 3A).

In the optical device having such a configuration, light from the light emitting portion 1H of the light source lamp 1 is reflected by the parabolic mirror 2, and the reflected light is incident on the first lens plate 3, and One lens plate 3 divides each lens element 3A. Then, each of the divided lights is converged on each of the corresponding lens elements 4A in the second lens plate 4. Then, the lens element 4 in the second lens plate 4
Each of the lights converged on A is irradiated by the lens element 4A in a state where the real image of the light emitting unit 1H is enlarged.
Are superimposed.

Here, the broken line in FIG.
Shows the optical path of the emitted light from the center of FIG. However, the light emitting portion 1H has a certain size, and the radiated light (not shown) from the end of the light emitting portion 1H is reflected by the parabolic mirror 2 so that the light with respect to the optical axis L Incident on the first lens plate 3 at a certain angle. As a result, at each position of the lens element 4A on the second lens plate 4,
A real image of the light emitting portion 1H of the light source lamp 1 is formed as a light spot. Thus, the size of the light spot formed at each position of the lens element 4A is such that the larger the light emitting portion 1H of the light source lamp 1, the smaller the focal length of the parabolic mirror 2, the smaller the size of the parabolic mirror 2, The larger the separation distance between the opening end face and the first lens plate 3, the larger the distance.

In the optical device having the configuration shown in FIG. 1, it is preferable that the focal length of the parabolic mirror 2 be small from the viewpoint of increasing the solid angle for capturing the light from the light emitting section 1H. Further, from the viewpoint of preventing deterioration (oxidation due to high heat) at the connection portion between the molybdenum foil 1M and the external lead rod 1L in the sealing portion of the light source lamp 1, the opening end face of the parabolic mirror 2 and the first end face are prevented. It is preferable to set a large separation distance (for example, about 20 mm) from the lens plate 3 to secure a flow path of the cooling air w.

[0007]

[Problems to be solved by the invention]

(1) However, if the separation distance between the opening end face of the parabolic mirror 2 and the first lens plate 3 is set to be large, it is necessary to set the size in the optical axis (L) direction to be large. It will be large.

(2) When the focal length of the parabolic mirror 2 is reduced and the separation distance between the opening end face of the parabolic mirror 2 and the first lens plate 3 is increased, the second lens plate The light spot formed at each position of the lens element 4A in 4 becomes larger than the opening of the lens element 4A. The lens element 4A of the light beam forming the light spot
The light that does not converge (light deviating from the lens element 4A) is
As a result, the light from the light source lamp 1 cannot be effectively used (reduction in light use efficiency).

To solve such a problem, it is conceivable to increase the aperture of the lens element 4A in the second lens plate 4 to improve the light use efficiency. However,
When the opening of the lens element 4A is enlarged, the light emitted from the lens element 4A located at the peripheral portion of the second lens plate 4 has a large irradiation angle with respect to the irradiation target area 7, so that F You need something with a small number. However, a projection lens with a small F / #
Since the effective diameter is large and expensive, the size and cost of the image projection device are increased.

The present invention has been made based on the above circumstances. A first object of the present invention is to provide an illumination optical device that is excellent in uniformity of illuminance in an irradiation area, has high utilization efficiency of light from a light source lamp, and has a compact configuration. A second object of the present invention is to provide an optical device capable of suppressing a temperature rise in a connection portion between a foil and an external lead bar in a sealing portion of a light source lamp and preventing deterioration in the connection portion. It is in. A third object of the present invention is an illumination optical device that can be suitably used for illuminating an image display element in an image projection device, and can contribute to downsizing and cost reduction of the image projection device. Is to provide.

[0011]

In order to achieve the above object, an optical device according to the present invention comprises sealing portions (11, 12) at both ends.
A light source lamp (10) having a short arc type, a concave reflecting mirror (20) arranged so that the optical axis coincides with the arc direction of the light source lamp (10), and a light from the concave reflecting mirror (20). A first lens plate (30) having a plurality of lens elements (30A) arranged in an optical path of reflected light
And a plurality of lens elements (40) corresponding to the lens elements (30A) of the first lens plate (30), which constitute an integrator optical system together with the first lens plate (30).
An optical device comprising: a second lens plate (40) having A), wherein a through hole (31) is formed at the center of the first lens plate (30), and the through hole (31) is formed. Are characterized in that a plurality of lens elements (30A) are arranged around.

In the optical device of the present invention, the following embodiments are preferable. [1] Cooling means (5) for supplying cooling air to the light source lamp (10) through the through hole (31) of the first lens plate (30).
0) is provided. [2] The distance between the opening end surface of the concave reflecting mirror (20) and the first lens plate (30) is 0 to 15 mm. [3] An ultraviolet reflecting film is formed on one surface of the first lens plate (30) facing the concave reflecting mirror (20). [4] The ultraviolet reflection film is made of a dielectric multilayer film. [5] When the concave reflecting mirror (20) is a parabolic mirror, the first lens plate (3) facing the concave reflecting mirror (20).
0) A reflection film is formed on one surface in a region where the lens element (30A) does not exist. [6] The lens element (30A) constituting the first lens plate (30) is rectangular. [7] The light source lamp (10) is a metal halide lamp or an ultra-high pressure mercury lamp.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical device according to the present invention will be described in detail. FIG. 3 is an explanatory diagram illustrating an example of the configuration of the optical device of the present invention. This optical device includes a light source lamp 1
0, a concave reflecting mirror 20 arranged so that the arc direction of the light source lamp 10 and the optical axis L coincide with each other, and a first reflecting mirror 20 mounted so that one surface thereof is in contact with the open end of the concave reflecting mirror 20. Lens plate 30 and second lens plate 4 forming an integrator optical system together with the first lens plate 30
0 and cooling means 50 for the light source lamp 10.
In FIG. 3, reference numerals 60 and 70 denote a condenser lens and a liquid crystal display element in the image projection device, respectively, and reference numeral 70A denotes an irradiated area in the liquid crystal display element 70.

The light source lamp 10 constituting the optical device is a short arc type metal halide lamp having sealing portions (11, 12) at both ends (electrodes are not shown in FIG. 1). Thereby, the light source lamp 1
Light with excellent uniformity of the spectral energy distribution can be efficiently emitted in the entirety of the light emitting unit 10H of zero. Here, the metal components sealed in the light source lamp 10 include dysprosium, indium, tin and the like, and the halogen components include iodine and bromine. A molybdenum foil 12M is embedded in the sealing portion 12 (cathode side) of the light source lamp 10, and an external lead rod 12L is connected to an outer end of the molybdenum foil 12M by welding. Note that the sealing portion 11 (on the anode side) also has the same configuration. Light emitting portion 10H of light source lamp 10
Is usually a column having a length of 1.0 to 3.0 mm. If the length (light emission length) of the light emitting unit 10H is too small, it may adversely affect the light emission characteristics and the lamp life. If the light emission length is too long, the light from the light source lamp cannot be used with high efficiency in the optical device provided with the light emission length.

The concave reflecting mirror 20 constituting the optical device is a parabolic mirror, the optical axis L of which is coincident with the arc direction of the light source lamp 10 (the length direction of the light emitting portion 10H) and at the focal point thereof. , And the light emitting unit 10H is arranged so that the center thereof is located. The focal length of the concave reflecting mirror 20 is preferably small from the viewpoint of increasing the angle at which light from the light emitting portion 10H of the light source lamp 10 is captured (from the viewpoint of reducing the size of the reflecting mirror), but the focal length is too small. in case of,
In the optical device provided with this, the light from the light source lamp cannot be used with high efficiency. Therefore, the focal length of the concave reflecting mirror 20 is preferably about 7 to 13 mm. The diameter (opening diameter) at the opening end of the concave reflecting mirror 20 is about 60 to 90 mm.

FIG. 4 is a front view (a front view as viewed from the concave reflecting mirror 20 side) showing the first lens plate 30 constituting the optical device. As shown in FIG. 4, the first lens plate 30 is made of, for example, Pyrex glass, and has a substrate 32 in which a through hole 31 is formed at the center (a region including the optical axis L).
And a plurality of (for example, 18) rectangular lens elements 30A arranged around the through-hole 31. Each of the lens elements 30A is disposed on the surface of the substrate 32 (the liquid crystal display element 70 side). They are arranged in close contact. Here, the size of the substrate 32 is set to such a size that the opening of the concave reflecting mirror 20 can be closed. The thickness of the substrate 32 is about 2 to 5 mm.

One surface of the first lens plate 30 (the concave reflecting mirror 2)
On the surface of the substrate 32 facing the substrate (0), an ultraviolet reflective film made of a dielectric multilayer film is formed.
An optical system such as a polarizing plate (not shown) existing in the optical path and the liquid crystal in the liquid crystal display element 70 can be effectively prevented from being deteriorated, and the first lens plate 30 can be effectively prevented from being distorted and cracked. Examples of such a dielectric multilayer film include a laminated film of a titanium oxide film and a silicon oxide film (the number of laminated layers: 11 to 25), and the film thickness is, for example, 1.0 to 2.6 μm. The ultraviolet reflection film may be formed not on the entire surface of the substrate 32 but only on the region where the lens elements 30A are arranged.

On one surface of the first lens plate 30 (the surface of the substrate 32 facing the concave reflecting mirror 20), a reflection film is formed in a region where the lens elements 30A are not arranged. Thus, the light from the concave reflecting mirror 20 can be effectively used. As such a reflective film,
Aluminum is used, and silicon oxide is used for the protective film.

The through-hole 31 formed in the center of the first lens plate 30 (substrate 32) serves as a cooling air flow path for cooling the light source lamp 10. Then, the through-hole 31 is formed in the first lens plate 30 in a central region where the illuminance of the light from the concave reflecting mirror 20 is relatively small (the optical axis L on which the shadow of the bulb of the light source lamp 10 is formed). In this case, the influence of the formation of the through-hole 31 on the light use efficiency (decrease in the amount of light) is extremely small.

The shape and size (area) of the through hole 31
Is not particularly limited, but specifically 25 to
It is preferably 100 mm ² (corresponding to a circle having a diameter of 5.6 to 11.3 mm). When the size of the through hole is too small, the cooling effect of the light source lamp 10 (the sealing portion 12) cannot be sufficiently exerted. On the other hand, if the size of the through hole is excessive, light leaking from the through hole causes
This leads to a decrease in light use efficiency.

The second lens plate 40 constituting the integrator optical system together with the first lens plate 30 has a plurality of lens elements 40A corresponding to each of the plurality of lens elements 30A in the first lens plate 30. ing. Specifically, a second lens plate is formed by arranging a substrate 42 made of Pyrex glass or soda glass and a plurality of lens elements 40A located at the focal point of each of the plurality of lens elements 30A. Here, the size and the thickness of the substrate 42 are substantially the same as the size and the thickness of the substrate 32 constituting the first lens plate 30.

The cooling means 50 constituting the optical device comprises a first
The configuration and position of the lens plate 30 are not particularly limited as long as it can supply cooling air toward the through hole 31 of the lens plate 30.

In the optical device having the above configuration, light from the light emitting portion 10H of the light source lamp 10 is
0, and the reflected light [a light beam including parallel light (indicated by a dotted line) in which light from the center of the light emitting section 10H is reflected] is attached so as to come into contact with the opening end of the concave reflecting mirror 20. Incident on the first lens plate 30. The light that has entered the first lens plate 30 is split by the first lens plate 30 for each lens element 30A, and each of the split light is applied to the corresponding lens element 40A of the second lens plate 40. Are converged to each. And the second
Each of the lights converged on the lens element 40A of the lens plate 40 of FIG.
The H real image is superimposed on the irradiated area 70A of the liquid crystal display element 70 in an enlarged state.

According to the optical device having the above configuration, the following effects can be obtained. <Uniformity of Illuminance in Irradiated Area> First Lens Plate 30
Are small in the difference between the luminous flux density near the center and the luminous flux density in the peripheral portion, and each of the divided light is divided by the second lens plate 40.
Is superimposed on the same illuminated area 70A, so that the illuminance in the illuminated area 70A is excellent in uniformity.

<Compact device size (optical axis direction)>
Is mounted so as to contact the opening end of the concave reflecting mirror 20 (the separation distance between the two is 0 mm), so that the size in the optical axis (L) direction can be set small, and The device has a compact configuration.

<High Light Use Efficiency> First Lens Plate 30
Are mounted so as to be in contact with the opening end of the concave reflecting mirror 20, so that a light spot formed at the position of each lens element 40A constituting the second lens plate 40 (real image of the light emitting unit 10H) Are very small, at least
It is smaller than the aperture of the lens element 40A.
Therefore, all of the light beams forming the light spot are converged on the lens element 4A and reach the irradiated area 70A. As a result, the light from the light source lamp 10 can be effectively used with high efficiency.

<Compact device size (direction perpendicular to the optical axis)> In order to improve light use efficiency, the lens element 4
Since it is not necessary to increase the aperture of 0A, the size in the direction perpendicular to the optical axis can be set small, and the optical device has a compact configuration.

<Longer Life of Light Source Lamp (Prevention of Deterioration at Connection between Foil and External Lead Rod)> First Lens Plate 30
Is formed at the center of the lens, and a cooling means 50 for supplying cooling air toward the through hole 31 is provided. Even if it is mounted so as to be in contact, the sealing portion 12 of the light source lamp 10 is surely cooled by the cooling air supplied through the through-hole 31, and the connection portion between the molybdenum foil 12M and the external lead rod 12L is formed. Is suppressed. As a result, it is possible to effectively prevent deterioration (oxidation due to high heat) in the connection portion.

As described above, an example of the embodiment of the optical device of the present invention has been described. However, the optical device of the present invention is not limited to this embodiment, and various modifications can be made. For example,
The first lens plate does not need to be mounted so as to be in contact with the opening end of the concave reflecting mirror, and has a range (for example, 15 mm) that does not affect the light use efficiency and the compactness of the device.
In the following, the distance between them can be set. The shape of the through-hole formed in the center of the first lens plate is not limited to a rectangle, but may be a circle or the like. In addition, a part of the sealing portion of the light source lamp is
May protrude from the lens plate.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. Example 1 An optical device having a configuration as shown in FIG. 3 was manufactured according to the following specifications. (1) Light source lamp 10: short-arc type metal halide lamp (power consumption 250 W, total length 75 mm, length of sealing portion 11 25 mm, cross-sectional area of sealing portion 11 35 mm ² ,
The outer diameter of the external lead rod 12L is 1 mm, and the emission length is 1.8 to 2.
4mm,)

(2) Concave reflector 20: Parabolic mirror (aperture diameter: 85 mm, focal length: 12 mm)

(3) First lens plate 30: lens element 30A (opening size: 15 mm × 11.
5 mm, number of 18) Substrate 32 (made of Pyrex glass, 75 mm × 70
mm × 2 mm) Through hole 31 (6 mm × 11.5 mm = 69 mm ² ) Dielectric multilayer film (laminated film of titanium oxide film and silicon oxide film, number of laminated layers) formed on one surface (concave reflecting mirror side) of substrate 32 : 36, film thickness 5 μm)

(4) Second lens plate 40: lens element 40A (opening size 15 mm × 11.
Substrate 42 (Pyrex glass, 68 mm × 60)
mm × 2mm)

(5) Cooling means 50: A part of cooling air from a fan for cooling the liquid crystal display element (0.2 cm ³ /
min) was supplied toward the through-hole 31.

(6) Separation distance between first lens plate 30 and second lens plate 40: 70 mm (7) Separation distance between second lens plate 40 and irradiated area 70A: 140 mm (8) Irradiation The size of the area 70A: 28.6m × 22m
m (9) Length of the external lead rod 12L protruding from the first lens plate 30 (the second lens plate side) is 6 mm.

When the above optical device was operated, the average illuminance in the irradiated area (70A) was about 7 million lux, and the illuminance was excellent in uniformity. Also,
When the temperature at the connection portion between the molybdenum foil (12M) and the external lead rod (12L) was measured using a thermocouple embedded in the sealing portion (12), it was 330 ° C.
Even after continuous operation for 000 hours, no deterioration was observed in the connection portion.

<Comparative Example 1> With the external lead rod (12L) protruding from the first lens plate (30), the through-hole (31) is closed and the flow path of the cooling air supplied to the light source lamp 10 is closed. By cutting off, an optical device for comparison was manufactured. Activate this optical device, molybdenum foil (12M)
When the temperature at the connection portion between the lead wire and the external lead rod (12L) was measured, it was considerably high at 390 ° C.
After operating continuously for 00 hours, observation of the connection portion showed that deterioration (oxidation due to high heat) occurred.

[0038]

The optical device according to the present invention has excellent uniformity of illuminance in the illuminated area, has a high use efficiency of light from the light source lamp, and has a compact configuration. Moreover, according to the optical device of the present invention, it is possible to suppress a temperature rise at a connection portion between the foil in the sealing portion of the light source lamp and the external lead rod, and to effectively reduce the deterioration (oxidation due to high heat) of the connection portion. Can be prevented. INDUSTRIAL APPLICABILITY The optical device of the present invention can be suitably used to illuminate an image display element in an image projection device, and can contribute to downsizing and cost reduction of the image projection device.

According to the optical device of the first and second aspects, even when the separation distance between the opening end of the concave reflecting mirror and the first lens plate is short, the cooling wind to the light source lamp can be reduced. By providing a flow path and supplying cooling air through the through-hole, it is possible to suppress a rise in temperature of a connection portion between the foil in the sealing portion of the light source lamp and the external lead rod. According to the optical device of the third aspect, the separation distance between the opening end of the concave reflecting mirror and the first lens plate is one.
Since it is as short as 5 mm or less, it has a compact configuration and can use light from the light source lamp with high efficiency.

According to the optical device of the fourth aspect, the deterioration of the liquid crystal in the liquid crystal display element and the optical members such as the polarizing plate existing in the optical path, and the distortion and crack of the first lens plate are effectively prevented. can do. According to the optical device of the fifth aspect, the light from the concave reflecting mirror can be effectively used.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a conventional optical device.

FIG. 2 is a front view of a first lens plate included in a conventional optical device.

FIG. 3 is an explanatory diagram illustrating an example of a configuration of an optical device according to the present invention.

FIG. 4 is a front view of a first lens plate constituting the optical device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Light-source lamp 10H Light-emitting part 11, 12 Sealing part 12M Molybdenum foil 12L External lead rod 20 Concave reflector 30 First lens plate 31 Through-hole 32 Substrate 30A Lens element 40 Second lens plate 40A Lens element 42 Substrate 50 Cooling Means 60 Condenser lens 70 Liquid crystal display element 70A Irradiated area

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02F 1/13 505 G02F 1/1335 1/1335 G02B 27/00 V

Claims (5)

[Claims] 1. A light source lamp (10) of a short arc type having sealing portions (11, 12) at both ends, and a concave reflection arranged so that an optical axis coincides with an arc direction of the light source lamp (10). A mirror (20); a first lens plate (30) having a plurality of lens elements (30A) disposed in an optical path of light reflected from the concave reflecting mirror (20); and a first lens plate. A plurality of lens elements (40A) corresponding to the lens elements (30A) of the first lens plate (30), which constitute an integrator optical system together with (30).
An optical device comprising a second lens plate (40) having a through hole (31) formed in the center of the first lens plate (30), and a periphery of the through hole (31). An optical device, wherein a plurality of lens elements (30A) are arranged. 2. The light source lamp (10) further comprising a cooling means (50) for supplying cooling air through a through hole (31) of the first lens plate (30). The optical device according to any of the preceding claims. 3. An open end face of said concave reflecting mirror (20);
The distance between the first lens plate (30) and the first lens plate (30) is 0-1.
3. The method according to claim 1, wherein the distance is 5 mm.
An optical device according to claim 1. 4. A first mirror facing a concave reflecting mirror (20).
The optical device according to any one of claims 1 to 3, wherein an ultraviolet reflective film is formed on one surface of the lens plate (30). 5. The concave reflecting mirror (20) is a parabolic mirror,
The reflection film is formed on a surface of the first lens plate (30) facing the concave reflecting mirror (20) in a region where the lens element (30A) does not exist. The optical device according to claim 4.