JPH11283422A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a light emitting point variation quantity in a second focus, to prevent the occurrence of uselessness of an effective light flux, and to reduce a flicker by arranging a light emitting point on a first focus of an ellipsoid of a reflecting means, and reflecting the light emitted to rearward of the light emitting point to the light emitting point by a spherical surface. SOLUTION: In a lamp 1 composed of a light emitting tube 3 and a reflector 2, a position of a light emitting point 3a of the light emitting tube 3 is set as a first focus F1 of the ellipsoidal part 2a of the reflector 2 so that the light is condensed on a second focus F2 . The rear part of a light emitting point 3 of the reflector 2 is formed as the spherical surface part 2b continuing with the ellipsoidal part 2a, or a part of the light emitting tube 3 is formed as the reflecting spherical surface part. Therefore, the light emitted to an aberration power large area 5 of the reflector 2 in the rear from the light emitting point 3a is reflected to the light emitting point 3a to be condensed on the second focus F2 through an aberration power small area 4, and even when the light emitting point 3a is moved by an arc jump or the like, condensing efficiency is increased without wasting an effective light flux to restrain a flicker of a projection image as a light source device of a projector.

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 used for a liquid crystal projector or the like.

[0002]

2. Description of the Related Art As a light source of a projection device such as a liquid crystal projector device, there is known a lamp configured to reflect light emitted from a light emitting portion thereof forward by, for example, an elliptical reflector.

FIG. 12 is a schematic diagram for explaining the structure of a conventional lamp. The lamp 30 is constituted by a reflector 31 as a reflection means having an elliptical reflection surface 31a having an inner surface provided with a reflection film, and an arc tube 32 arranged in the reflector 31. The light emitting point 32 a of the light emitting tube 32 is arranged at the first focal point F 1 of the reflector 31. As a result, light emitted from the light emitting point 32a and reflected by the reflection surface 31a is reflected by the second focal point F of the reflector 31.
In 2, the light source image is formed with no aberration.

[0004]

By the way, the arc tube 32
In, the light emitting point 33a that actually emits light cannot always be said to be discharging at a fixed position, and when its random movement, that is, an arc jump (light emitting point movement) occurs, the light emitting point 33a becomes the first. It deviates from the focal point F1, which increases the aberration at the second focal point F2. The magnification of the aberration due to the arc jump is determined by the optical path in the reflector 31. For example, the magnification at the reflection position P1 shown in FIG. 12 can be represented by P1F2 / P1F1, and the aberration magnification of the light reflected at the reflection position P2 relatively close to the light emitting point 33a is P2F2 /
It can be indicated by P2F1. Then, when an arc jump occurs and the position of the light emitting point 33a changes, the light reflected at a position closer to the position P0 where the light emitting tube 32 is disposed has a larger aberration magnification. Therefore, the first focus F1
Even when the moving amount of the light emitting point generated in is small, the second focus F2 is in the same state as the case where the moving amount of the light emitting point is large due to the aberration magnification.

If the amount of movement of the light emitting point at the second focal point F2 is large, light that does not form an image is generated at the second focal point F2, so that a large amount of light deviates from the effective optical path in the optical design of the liquid crystal projector device, and the projected light is reduced. A phenomenon occurs in which the image becomes darker due to the decrease. As described above, the amount of movement of the light emitting point in the light emitting tube 32 appears in an image projected as flicker (fluctuation in the amount of light) when used in a liquid crystal projector device, and thus has a problem of deteriorating the quality of image quality.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention can reflect an arc tube and light emitted from the arc tube so as to be condensed in a predetermined direction. In a light source device comprising a reflecting means, the reflecting means sets a light emitting point of the arc tube as one focal position,
It is formed by an elliptical surface formed so that light emitted forward is the other focal position, and a spherical surface that reflects light emitted backward from the light emitting point of the arc tube to the light emitting point.

According to the present invention, since the reflection means has a spherical surface behind the light emitting point of the arc tube, the aberration magnification at the second focal point of the reflection means can be reduced.
Even when an arc jump occurs, it is possible to efficiently focus light on the second focal point.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the light source device according to the present invention will be described below. FIG. 1 is a diagram illustrating the configuration of the lamp according to the present embodiment. The lamp 1 shown in FIG. 1 includes a reflector 2 having an elliptical surface portion 2a and a spherical surface portion 2b as reflection surfaces, and an arc tube 3, and the light emitting portion 3a of the arc tube 3 has a first focal point of the elliptical surface portion 2a. It is arranged so as to coincide with F1. Further, a spherical portion 2b is formed behind the elliptical surface portion 2a around the first focal point F1. That is, in the related art, a portion corresponding to a position where the aberration magnification is large (near the reflection position P2) is formed as the spherical portion 2b.

The first focal point F of the ellipse forming the elliptical surface 2a
Assuming that the coordinates of 1 are (c, 0), major axis a, and minor axis b, x =
The y coordinate at the time of c is an equation representing an ellipse

(Equation 1) By

(Equation 2) Therefore, the radius r of the spherical portion 2b is

(Equation 3) Can be indicated by That is, the spherical portion 2b is configured as a spherical reflector having a radius r.

The area 4 indicated by hatching corresponds to the area (near the reflection position P1) where the aberration magnification is small in the conventional reflector 31 shown in FIG. An image is formed at the bifocal F2. The area 5 corresponds to an area where the aberration magnification is large in the reflector 31 (near the reflection position P2). Light emitted to this area is reflected by the spherical portion 2b and returns to the light emitting point 3a again. It is led to. Then, since the light is reflected by the elliptical surface portion 2a in the region 4, an image is formed on the second focal point F2 with a small aberration magnification.

By forming the spherical portion 2b around the first focal point F1 in the reflector 2 as described above, it is possible to reduce the area where the aberration magnification is large. Therefore, even when the light emitting point 3a moves due to an arc jump or the like, the aberration magnification at the second focal point F2 can be reduced. This makes it possible to suppress the flicker of the projected image while maintaining the light collection efficiency of the elliptical reflector without wasting the effective light flux.

Further, since the influence of the aberration magnification at the second focal point F2 due to the arc jump is small, even when a light emitting point having a long arc length is applied, the condensed spot at the second focal point F2 can be reduced, and Usage efficiency can be improved.

Further, since the distance between the arc tube 3 and the reflecting surface of the reflector 2 can be increased, the heat resistance can be improved and the size of the reflector 2 can be reduced.

Next, an example in which the lamp 1 of the present embodiment is applied to a single-panel type liquid crystal projector according to FIG. 2 will be described. After the light emitted from the lamp 1 is imaged at the second focal point F2 via the UV / IR cut filter 5,
The light is converted into parallel light by the collimating lens 6 and enters the first lens array 7. Each lens 7a formed in the first lens array 7 has an image conjugate relationship with a region to be irradiated of the liquid crystal panel 12, which will be described later, and thus has a shape similar to or similar to the region to be irradiated. The second lens array 8 has a plurality of lenses formed in an irregular shape corresponding to the first lens array 7 on a one-to-one basis. That is,
The lenses 7a of the first lens array 7 are eccentric so as to collect the incident light and guide the light to a predetermined lens in the second lens array 8. Further, since the second lens array 8 plays a role of a stop portion of incident light to the liquid crystal panel 12 and also serves as a field lens, it is necessary to decenter each lens as needed. The first lens array 7 and the second lens array 8 will be described later in detail with reference to FIGS.

The light diffused by passing through the second lens array 8 is converted again by the collimating lens 9 into parallel light, and the dichroic mirrors 10R, 10G,
The light enters the color separation unit 10 made of 10B. The dichroic mirror 10R is, for example, an R light, a dichroic mirror 1
0G is, for example, a G light, and a dichroic mirror 10B.
Are configured to be able to reflect the B light, and are arranged with a predetermined tilt angle. This gives R
Each of the GB color lights is reflected at a different angle corresponding to the tilt angle.

The RGB color lights separated by the color separation section 10 are incident on a liquid crystal panel 12 via a polarizing plate 11. The liquid crystal panel 12 is provided with a microlens on the incident side thereof, for example, for every three pixels (one pixel as a color pixel) corresponding to each color light of RGB, and condenses the incident RGB light to each color pixel. Are to be distributed. Then, each color light modulated by the liquid crystal panel 12 is enlarged and projected on the screen 14 by the projection lens 13.

FIG. 3 is a diagram showing the first lens array 7 from the front. As described above, the first lens array 7 has a shape substantially similar to the illuminated area of the liquid crystal panel 12, for example, lenses 7 a, 7 a, 7 a.
.. Are arranged. The lens 7a
The more is formed, the more suitable the brightness becomes in the illuminated area. In the present embodiment, for example, 36 lenses 7a are arranged. In the present invention, the light emitted from the lamp 1 has a dark central portion (shaded portion) in the first lens array 7 and a bright peripheral portion. Therefore, the peripheral portion of the lamp image focused on each lens of the second lens array 8 becomes brighter than the central portion.

Next, a configuration example of the second lens array 8 will be described with reference to FIG. The ellipses shown in these figures show the lamp images formed through the first lens array 7. FIG. 4A shows a lens array 40 on which lenses 40a, 40a, 40a,... Having a uniform shape are formed, for example. When this lens array 40 is used as the second lens array, a portion (shaded portion) where the lamp image protrudes from the lens 40a occurs in a peripheral portion having high luminance. The light protruding from the peripheral lens 40 a protrudes from the lens array 40 and cannot reach the liquid crystal panel 12. In other words, light that does not contribute to image formation is generated, so that the light use efficiency is reduced.

Therefore, as shown in FIG. 4B, for example, the lenses 8c and 8d formed in the peripheral portion are made larger than the lenses 8a and 8b formed in the central portion as the second lens array 8. Form. In this way, by making the lens formed in the peripheral portion large, it becomes possible to take in bright light entering the position protruding from the lens array 40 in FIG. Can be improved.

The liquid crystal panel 12 (micro lens)
Since the angle of divergence of incident light with respect to is limited by the size of the second lens array 8 which is a stop, it is advantageous to make the second lens array 8 as small as possible in terms of condensing the liquid crystal panel 12. become. That is, by forming the entire second lens array 8 small, it is possible to improve the light collection efficiency with respect to the pixels using the microlenses. Therefore, each lens of the second lens array 8 is formed so as to be eccentric so that the lamp images are gathered as much as possible and dense.

As described above, the first lens array 7 is designed so as to take in as much light from the lamp 1 as possible, and the second lens array 8 converts the light collected by the first lens array 7 into light. By designing the liquid crystal panel 12 to be efficiently guided to the liquid crystal panel 12, the light from the lamp 1 can be effectively used.

FIGS. 5 to 10 show comparisons between simulations performed under specific conditions for the lamp 1 of the present embodiment and the conventional lamp 30. FIG.

FIG. 5A shows a conventional lamp 30 and FIG.
(B) shows a spot diagram of the second focal point F2 when the light emitting point is changed by about 200 μm in the y-axis direction for the lamp 1 of the present embodiment. As can be seen by comparing the spot diagrams shown in these figures, the shift of the condensed spot is large in the related art, but in the present embodiment, the shift of the condensed spot is reduced by reducing the aberration magnification. You can see that there is. FIGS. 6A and 6B respectively show the optical path from the side when the observation film 15 of, for example, φ1 is disposed at the second focal point F2, corresponding to FIGS. 5A and 5B. As shown in these figures, the lamp 30 partially deviates from the film in the lamp 30, but it can be seen that the lamp 1 of the present embodiment forms an image on the film 15. That is, the light use efficiency can be maintained without being affected by the fluctuation of the light emitting point.

FIG. 7A shows the lamp 30, FIG.
(B) shows a spot diagram of the second focal point F2 when the lamp 1 of the present embodiment has an arc length of, for example, 1.4 mm. As can be seen by comparing the spot diagrams shown in these figures, it can be seen that the converging spot of the lamp 1 of the present embodiment is smaller than the converging spot of the lamp 30. FIGS. 8A and 8B show FIGS. 7A and 7B, respectively.
The optical path when the observation film 16 of, for example, φ6 is disposed at the second focal point F2 is shown from the side. As shown in these figures, although the lamp 30 partially deviates from the film, it can be seen that the lamp 1 of the present embodiment forms an image on the film 16. Therefore, even when the arc length is long, it is possible to efficiently collect light.

FIG. 9A shows a lamp 30 and FIG.
(B) shows a spot diagram at the second focal point F2 when the arc length of the lamp 1 of the present embodiment is set to, for example, 1.4 mm and the light emitting point is changed by about 200 μm in the y-axis direction. . As you can see by comparing the spot diagrams shown in these figures,
It can be seen that the light spot of the lamp 1 of the present embodiment has a smaller fluctuation of the light spot than the light spot of the conventional lamp 30 and forms an image in a small area. FIGS. 10A and 10B respectively show FIGS.
(B) shows the optical path from the side when the observation film 16 of, for example, φ6 is arranged at the second focal point F2. As shown in these figures, the conventional lamp 3
In the case of 0, although some light rays deviate from the film, it is understood that the lamp 1 of the present embodiment forms an image on the film. That is, even when an arc jump occurs when the arc length is long, the light use efficiency can be maintained.

Next, a modification of the present invention will be described with reference to FIG. The lamp 20 shown in FIG. 11 includes a reflector 21 having an elliptical surface portion 21a formed as a reflection surface, and an arc tube 22. The spherical surface of the arc tube 22 is directly coated with the reflective film 22a.
The reflection film 22a is formed as a spherical surface centered on the light emitting point, and the same effect as that shown in FIG. 1 can be obtained. That is, the light emitted to the region 23 having the large aberration magnification is reflected by the reflection film 22a and passes through the light emitting point, is emitted to the region 24 having the small aberration magnification, and is imaged at the second focal point F2. .

As described above, by forming the reflective film 22a on the spherical portion of the arc tube 22, compared to the reflector 2 of the lamp 1 shown in FIG. A smaller reflector 21 can be configured. In this case, the heat resistance of the reflective film 22a is required, but this can be realized by forming a reflective film having excellent heat resistance.

[0028]

As described above, according to the present invention, even if the light emitting point fluctuates due to an arc jump or the like, the amount of fluctuation of the light emitting point at the second focus can be suppressed. There is no. Therefore, in the liquid crystal projector device to which the present invention is applied, an image with less flicker can be formed. In addition, even when an arc tube having a long arc length is used, the condensing spot at the second focal point can be made smaller than that of a conventional elliptical reflector, and the condensing efficiency can be improved. Furthermore, since the distance between the light emitting point and the reflecting surface of the reflector is increased, the heat resistance can be improved, and the size of the reflector can be reduced while maintaining the power of the arc tube. In addition, by forming the reflective film directly on the spherical portion of the arc tube, it is possible to achieve a reduction in size because no spherical portion is formed behind the reflector.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a lamp according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an optical system of a liquid crystal projector using the lamp according to the embodiment.

FIG. 3 is an explanatory diagram of a first lens array shown in FIG. 2;

FIG. 4 is an explanatory diagram of a second lens array shown in FIG. 2;

FIG. 5 is a diagram showing spot diagrams of a conventional example and the present invention at a second focus when the light emitting point is changed by about 200 μm in the y-axis direction.

FIG. 6 is a side view showing an optical path when a film of φ1 is arranged at a second focal point in FIG. 5;

FIG. 7 is a diagram showing spot diagrams of a conventional example and the present invention at a second focal point when the arc length of a light emitting point is set to about 1.4 mm.

FIG. 8 is a side view showing an optical path when a φ6 film is arranged at a second focal point in FIG. 7;

FIG. 9 is a diagram showing a spot diagram of a conventional example and a spot diagram of the present invention at a second focal point when the arc length of a light emitting point is set to about 1.4 mm and is changed by about 200 μm in the y-axis direction.

FIG. 10 is a side view illustrating an optical path when a φ6 film is disposed at a second focal point in FIG. 9;

FIG. 11 is a diagram illustrating a configuration of a modified example of the present invention.

FIG. 12 is a diagram illustrating a configuration of a conventional lamp.

[Explanation of symbols]

1,20 lamp, 2,21 reflector, 2a, 21
a Elliptical surface part, 2b spherical part, 3, 22 arc tube, 22a
Reflective film

Claims (3)

[Claims] 1. A light source device comprising: a light emitting tube; and a reflecting means capable of reflecting light emitted from the light emitting tube so as to condense the light in a predetermined direction. An elliptical surface formed so that the light emitting point of the arc tube is set as one focal position and light emitted forward is set as the other focal position, and light emitted backward from the light emitting point of the arc tube. Is formed by a spherical surface that reflects light to the light emitting point. 2. The light source device according to claim 1, wherein the elliptical surface and the spherical surface are formed by a continuous surface. 3. The light source device according to claim 1, wherein the spherical surface forming the reflecting means has a part of the arc tube formed as a spherical portion.