JP2000347293A - Light source device, illumination optical system and projector including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for improving the parallelism of light emitted from a light source device. SOLUTION: This light source device 150A is equipped with a light source lamp 25 constituted of a discharge lamp 22 and an elliptical reflector 24 and an aspherical lens 30A. The lens 30A is constituted so that its incident surface 30Ai is a plane and its emitting surface 30Ao is an aspherical concave. By making the shape of the aspherical surface a paraboloid of revolution decided on the basis of a specified formula, the light having the high parallelism is emitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light source device, an illumination optical system having the light source device, and a projector.

[0002]

2. Description of the Related Art In a projector, an illumination light emitted from an illumination optical system is modulated according to image information using a modulator such as a liquid crystal panel, and the modulated illumination light is projected on a screen. Display is realized.

In such a projector, in order to make the in-plane illuminance distribution of illumination light illuminating the modulation device uniform, the light emitted from the light source lamp is divided into a plurality of partial light beams, and the vicinity of the modulation device is divided. An integrator illumination optical system for superimposing is used. In such an integrator illumination optical system, an integrator illumination optical system (uniform illumination optical system) using a light source lamp having an elliptical reflector and a lens array usually collimates light emitted from the elliptical reflector. In order to make the light incident on the lens array, a spherical concave lens is provided between the light source lamp and the lens array. That is, a light source device that emits parallel light is constituted by a combination of a light source lamp and a spherical concave lens.

[0004]

However, the light beam emitted from such a light source lamp has a high degree of parallelism at the center but a poor degree of parallelism at the periphery. This is because spherical aberration occurs in the concave lens. Light rays having poor parallelism cannot be passed through a lens array well in an illumination optical system or in an apparatus such as a projector using such an illumination optical system, and are often wasted. For this reason, in the conventional illumination optical system,
It has been difficult to efficiently use the light emitted from the light source lamp.

[0005] The present invention has been made to solve the above-mentioned problems in the prior art, and has as its object to provide a technique for improving the parallelism of light emitted from a light source device.

[0006]

In order to solve at least a part of the above-mentioned problems, a light source device according to the present invention comprises a discharge lamp and a reflecting surface for reflecting light emitted from the discharge lamp. And a lens for collimating the light reflected by the reflection surface, wherein the lens has a rotational quadratic curved surface on one of the entrance surface and the exit surface. It is an aspheric lens having a spherical surface.

The light source device of the present invention has an aspheric lens having an aspheric surface of a quadratic curved surface on one of the incident surface and the exit surface, so that the parallelism of emitted light can be reduced. It can be improved.

In the above light source device, the aspheric surface is represented by r and Z in an rθZ cylindrical coordinate system axially symmetric with respect to an optical axis having an origin at an intersection of the aspheric surface and the light source optical axis;
When the paraxial curvature is c and the conic constant is K,

(Equation 6) Is preferred.

In this case, the shape of the aspherical surface can be easily determined. Also, if a lens having an aspheric surface determined based on this equation is used, the spherical aberration can be considerably reduced, so that the parallelism of the light emitted from the light source device can be significantly improved.

In the above light source device, it is preferable that the aspheric surface is a concave surface. In this case, since the lens can be disposed between the first focus and the second focus of the elliptical reflector, the size of the light source device can be reduced.

At this time, the aspheric lens may be joined to an opening surface of the elliptical reflector. In this case, the size of the light source device can be further reduced, and the aspheric lens can function as a front glass of the light source device.

However, in the above light source device, the aspheric surface may be a convex surface.

In the above light source device, when the lens has an aspheric surface that is concave or convex and the exit surface is an aspheric surface, the aspheric surface preferably has a spheroidal shape.

When the exit surface is aspheric, the diameter of the emitted light beam can be reduced. Therefore, when the light source device is used for an illumination optical system or a projector,
Since the size of the optical element disposed downstream of the light path from the light source device can be reduced, there is an effect that the illumination optical system and the projector can be reduced in size. Furthermore, when the exit surface is made aspherical, there is also an effect that the variation in the in-plane illuminance of the emitted light beam can be made relatively small.

At this time, the spheroidal surface is an rθZ cylindrical coordinate having the origin at the intersection of the aspheric surface and the light source optical axis, the Z-axis of the light source optical axis, and the r-axis perpendicular to the light source optical axis. The coordinate values in the system are r and Z, the paraxial curvature is c,
When the conic constant is K,

(Equation 7) The elliptical reflector has an origin at an intersection of the reflection surface and the optical axis of the light source, a z-axis of the optical axis of the light source, and an rθZ cylindrical coordinate with an axis orthogonal to the optical axis of the light source as an r-axis. When the coordinate values in the system are r _R and Z _R , the paraxial curvature is c _R , and the conic constant is K _R ,

(Equation 8) Where −0.8 <K _R <−0.
It is preferably 5.

This makes it possible to easily determine the shape of the spheroid. Also, if a lens having an aspheric surface determined based on this equation is used, the spherical aberration can be considerably reduced, so that the parallelism of the light emitted from the light source device can be significantly improved.

In the above light source device, when the aspherical surface of the lens is a concave surface or a convex surface, and the exit surface is a spheroidal surface, it is preferable that the entrance surface of the lens is a spherical surface.

In this way, it is possible to prevent light from being refracted at the entrance surface of the lens.
It is possible to obtain emission light with higher parallelism.
Note that when the incident surface is flat, the parallelism of the emitted light is slightly worse than when the incident surface is spherical, but by making one of the aspheric lenses flat, the aspheric lens can be relatively There is an advantage that it can be produced at low cost.

When the aspherical surface of the lens is a concave or convex surface, the exit surface is a spheroidal surface, and the entrance surface is a spherical surface, the spheroidal surface has an origin at the intersection of the aspherical surface and the optical axis of the light source. The light source optical axis is the Z axis, the coordinate values in the rθZ cylindrical coordinate system with the axis orthogonal to the light source optical axis as the r axis are r and Z, the paraxial curvature is c, the conic constant is K, and the conic constant is K. When the refractive index is n,

(Equation 9) Preferably, the shape is represented by This makes it possible to easily determine the shape of the spheroid.

In this light source device, an ultraviolet reflective film may be formed on the incident surface of the aspheric lens. This can prevent the ultraviolet light from being emitted from the light source device. Further, the intensity of the visible light emitted from the light source device can be improved by reflecting the ultraviolet light emitted from the discharge lamp and returning to the discharge lamp again.

In the above light source device, when the aspherical surface of the lens is a concave surface or a convex surface and the incident surface is an aspherical surface, it is preferable that the aspherical surface has a shape of a rotating hyperboloid.

When the entrance surface is aspheric, the light reflected on the reflection surface of the elliptical reflector is collimated on the entrance surface of the lens, and can be prevented from being refracted on the exit surface. Therefore, it is possible to obtain emission light with higher parallelism.

At this time, the rotational hyperboloid is an rθZ cylindrical coordinate having an origin at an intersection of the aspheric surface and the optical axis of the light source, a Z-axis at the optical axis of the light source, and an r-axis orthogonal to the optical axis of the light source. The coordinate values in the system are r and Z, the paraxial curvature is c,
When the conic constant is K and the refractive index of the lens is n,

(Equation 10) Is preferred.

In this manner, the shape of the hyperboloid of revolution can be easily determined. Also, if a lens having an aspheric surface determined based on this equation is used, the spherical aberration can be considerably reduced, so that the parallelism of the light emitted from the light source device can be significantly improved.

In this light source device, the emission surface of the aspheric lens may be flat, and an ultraviolet reflection film may be formed on the emission surface of the aspheric lens. This can prevent the ultraviolet light from being emitted from the light source device. Further, the intensity of the visible light emitted from the light source device can be improved by reflecting the ultraviolet light emitted from the discharge lamp and returning to the discharge lamp again.

The above-described light source device has a lens array that divides the light emitted from the light source device into a plurality of partial light beams, and a superposition lens that superimposes the partial light beams divided by the lens array on an illumination area. , Can be used as a light source device.

In a case where the illumination optical system uses a light source device having an aspheric lens having a hyperboloid-shaped entrance surface and a flat exit surface, the lens array is provided on the exit surface of the aspheric lens. May be. This makes it possible to reduce the size of the illumination optical system.

Further, the above light source device has a light incident surface as an illumination area illuminated by the light source device, and modulates incident light from the light source device in accordance with image information; And a projection optical system that projects the light modulated by the device, the projector can be used as a light source device.

By using the above light source device as a light source of an illumination optical system or a projector, it is possible to improve the light use efficiency and to improve the brightness of a projected image.

[0030]

DETAILED DESCRIPTION OF THE INVENTION Light source device 150A: FIG.
FIG. 2 is an explanatory diagram showing a light source device 150A according to the first embodiment of the present invention. The light source device 150A includes a light source lamp 25 including a discharge lamp 22 and a reflector 24, and an aspheric lens 30A. The reflector 24 is an elliptical reflector having a reflection surface 24R formed of a spheroid symmetrical with respect to the light source optical axis 20ax. A spheroid, for example,
It is formed using glass. A dielectric multilayer film is formed on the reflection surface 24R. In addition, on the reflection surface 24R,
A metal reflection film such as an aluminum film or a silver film may be formed.

The discharge lamp 22 emits light radially. The center 22c of the discharge lamp 22 is located at a position (first focal point) closer to the elliptical reflector 24 among the two focal points on the light source optical axis 20ax of the elliptical reflector 24. Here, the center of the discharge lamp means the center of the arc of the discharge lamp 22. The emitted light emitted from the discharge lamp 22 is reflected by the elliptical reflector 24, and the reflected light goes to the other focal point (second focal point) of the elliptical reflector 24. As the discharge lamp 22, a metal halide lamp, a high-pressure mercury lamp, or the like is used. The light source optical axis 20ax
Is the central axis of the light beam emitted from the light source device 150A.

The aspheric lens 30A includes an elliptical reflector 2
4 has a function of converting the light reflected by the light 4 into substantially parallel light. The aspheric lens 30A shown in FIG.
The entrance surface 30Ai is a flat surface, and the exit surface 30Ao is an aspheric concave surface.

FIG. 2 shows a light source device 150 according to this embodiment.
3A illustrates the trajectory of light rays radially emitted from the center of the discharge lamp 22. 2, the illustration of the discharge lamp 22 (FIG. 1) is omitted. FIG.
FIG. 3 is an explanatory diagram showing a relationship between a reflection surface 24R of an elliptical reflector of the light source device 150A shown in FIG. 2 and the aspheric lens 30A. Emitted from the first focal point FR1 of the reflection surface 24R,
The light beam reflected by the reflecting surface 24R is reflected on the second surface of the reflecting surface 24R.
It proceeds in the direction of the focal point FR2, and is collimated by the aspherical lens 30A. In FIG. 3, Fe1 and Fe2 are the first focal point and the second focal point of the aspheric surface of the aspheric lens 30A, respectively. In the light source device 150A according to this embodiment, the shape of the aspheric surface of the exit surface 30Ao of the aspheric lens 30A is
By making the shape almost satisfying the relationship of the expression (1),
That is, unlike a conventional light source device, light having a high degree of parallelism can be emitted by adopting a rotation quadric surface shape.

[0034]

[Equation 11]

Here, as shown in FIG. 3, r and Z are the intersections of the aspherical surface of the aspherical lens 30A and the light source optical axis 20ax as the origin L0, and the rθZ cylindrical coordinate system is symmetrical with the light source optical axis 20ax. Is the coordinate value at. In FIG. 3,
In the Z direction, the direction from the first focal point FR1 to the second focal point FR2 of the reflection surface 24R is defined as positive. r indicates a distance from the origin L0 in a direction orthogonal to the light source optical axis 20ax. θ indicates an angle from a predetermined r direction,
As can be seen from equation (1), the shape of the aspheric surface does not depend on the angle θ.

In the equation (1), the paraxial curvature c is obtained by assuming that the light beam reflected by the reflecting surface 24R is converted into parallel light using a spherical concave lens as in the prior art.
The curvature of the spherical surface is shown. That is, in the paraxial region (region near the rotation axis), by using the concave lens having the curvature c, the light beam reflected by the reflection surface 24R can be converted into parallel light.

K is a value called a conical constant. By the value of the conic constant K, the shape of the rotational quadric surface is limited to a specific shape. That is, the value of the conic constant K is −1 <K
If <0, the aspheric surface is a spheroid. When the value of the conical constant K is K = -1, the aspheric surface becomes a paraboloid of revolution. Furthermore, when the value of the conic constant K is K <
If it is -1, the aspheric surface becomes a hyperboloid of revolution.

The third term on the left side is a function called a general aspheric term and depends on the distance r. However, since it is a sufficiently small value, it is ignored in this embodiment.

The rotational quadratic surface shape of the aspherical surface of the aspherical lens 30A in this embodiment is determined by the following method based on the following equation (2) ignoring the third term on the left side of equation (1). You.

[0040]

(Equation 12)

First, the shape of the reflection surface 24R of the elliptical reflector, the curvature of the entrance surface 30Ai of the aspherical lens 30A, and
The refractive index n of the aspherical lens 30A and the aspherical lens 30A
The value of the approximate curvature c is determined in consideration of the thickness of the central portion of the above and the installation position of the aspherical lens 30A. Specifically, the shape of the reflecting surface 24R and the incident surface 30A of the aspherical lens 30A
The curvature of i, the refractive index n of the aspherical lens 30A, the thickness at the center of the aspherical lens 30A, and the installation position of the aspherical lens 30A are determined in advance. Then, for an elliptical reflector having a reflection surface of the same shape as the predetermined reflection surface 24R, a spherical concave lens having the same curvature, refractive index, and center thickness of the incident surface is used at a predetermined position. In this case, a curvature that can be converted into parallel light in a paraxial region (a region near the rotation axis) is obtained. The value of the curvature obtained in this manner becomes the approximate curvature c. Here, like the light source device 150A of the present embodiment, the entrance surface 3 of the aspherical lens 30A
When 0Ai is a plane, the curvature of the incident surface 30Ai is set to 0.

Next, a cone constant K is obtained. In the light source device 150A of the present embodiment, the conical constant K is set to a condition under which parallel light is emitted by performing a simulation using the repetition formula (2) while changing its value. In this simulation, when the light beam emitted from the light source device 150A is condensed by an ideal lens having no aberration, the condition where the light spot diameter at the light condensing point becomes the smallest is the condition under which substantially parallel light is emitted. It is conceivable that In practice, the light spot diameter at the focal point is about 100μ
There is no problem even if the case where the distance is within m is considered as a condition under which substantially parallel light is emitted.

FIG. 4 shows the conic constant K obtained as a result of the simulation and the aspherical lens 3.
It is a graph which shows the relationship with the refractive index n of 0A. FIG. 4 shows the value of the conical constant K in a range of a refractive index n of 1.45 to 1.95, which is a general lens material of an aspherical lens. Each of the curves CA1 to CA6 has a different shape of the reflection surface 24R. Reflective surface 24 of elliptical reflector
The shape of R can be expressed using the same equation (3) as the above-mentioned equation (2).

[0044]

(Equation 13)

Where r_R, Z_RIs the reflection surface 24R and the light source
The point of intersection with the optical axis 20ax is the origin, and the light source optical axis 20ax is
It is a coordinate value in the rθZ cylindrical coordinate system that is an axis target. Ma
C _RIs the paraxial curvature of the elliptical reflector, K_RIs the conic constant
is there. The curves CA1 to CA6 respectively correspond to the equations (3).
And the conical constant K of the reflecting surface 24R_RIs -0.50,-
0.54, -0.66, -0.70, -0.80,-
It shows the value when it is 0.89.

As can be seen from FIG. 4, the light source of the present embodiment
In the device 150A, the conic constant K _RIs -0.8 <K_R<
Elliptical reflector having a reflective surface 24R in the range of -0.5
Is used, the aspherical cone of the aspherical lens 30A is used.
The constant K is in the range of −0.55 <K <−1, that is,
It is preferable to have a spheroidal shape.

As shown by the curve CA6 in FIG. 4, when the conical constant K _R of the reflecting surface 24R is −0.89 in the equation (3), the refractive index n of the aspherical lens 30A is Is 1.45 ≦ n <1.84, the conic constant K is K <
−1, and when n = 1.84, K = 1, and n>
When 1.84, K <-1. That is, in this case, the aspherical surface of the aspherical lens has a spheroidal surface in a region of n <1.84, a paraboloid of revolution when n = 1.84,
In a region where n> 1.84, a rotational hyperboloid is formed. In addition,
At this time, K _R is close to 1, that is, the shape of the reflection surface 24R of the elliptical reflector is close to a paraboloid. In this case, the light reflected by the reflection surface 24R is almost a parallel light state without being parallelized by the lens. Therefore, it is not necessary to use an aspherical lens for parallelization. In this case, since the diameter of the aspherical lens becomes relatively large, the diameter of the light beam emitted from the aspherical lens also becomes relatively large. Therefore, the effect of reducing the size of the optical system after the light source device cannot be expected much. From this, it is considered that when K _R is close to 1, it is not very practical. However, when it is necessary to obtain a light beam with a high degree of parallelism, it is conceivable to use the aspheric lens 30A as in the present embodiment even when K _R is close to 1.

The light source device 150A according to this embodiment
In this case, as shown in FIG. 3, the second focal point Fe2 of the aspheric surface of the aspheric lens 30A does not coincide with the second focal point FR2 of the reflection surface 24R of the elliptical reflector. This is because the light traveling toward the second focal point FR2 of the elliptical reflector undergoes a refraction action on the incident surface 30Ai of the aspheric lens 30A. As in a light source device 150B according to another embodiment described later, when light traveling toward the second focal point FR2 of the elliptical reflector undergoes a refraction effect only at the aspherical portion of the aspherical lens, the aspherical second focal point is used. Fe2 coincides with the second focal point FR2 of the reflection surface of the elliptical reflector.

As described above, in the light source device 150A according to the present embodiment, the shape of the aspherical surface of the exit surface 30Ao of the aspherical lens 30A is calculated by using the expression (2) of the expression (1) ignoring the third term on the left side. By adopting a shape satisfying the relationship, that is, by adopting a quadratic curved surface shape, unlike the conventional light source device, light with high parallelism can be emitted. In the light source device 150A of the present embodiment, the aspherical conical constant K of the aspherical lens 30A is preferably a spheroidal shape.

B. Light source device 150B: FIG. 5 is an explanatory view showing a modification of the light source device 150A according to the first embodiment shown in FIGS. In the light source device 150A, the incident surface 30Ai of the aspheric lens 30A is a flat surface.
In the present embodiment, the incident surface 30Bi of the aspherical lens 30B
Is a spherical surface. Since the configuration other than the aspheric lens 30B is the same as that of the light source device 150A according to the first embodiment, the same reference numerals as those used in FIGS. 1 to 3 are assigned, and the detailed description is omitted. I do.

In the light source device 150B according to the present embodiment, light rays emitted from the first focal point FR1 of the reflecting surface 24R of the elliptical reflector and reflected by the reflecting surface 24R travel in the direction of the second focal point FR2 of the reflecting surface 24R. , Aspheric lens 3
It is parallelized by 0B. In FIG. 5, Fe1, F
e2 is the first aspherical surface of the aspherical lens 30B.
Focus, second focus.

The spherical surface of the entrance surface 30Bi of the aspheric lens 30B is the second focal point FR2 of the reflection surface 24R of the elliptical reflector.
. The exit surface 30Bo of the aspheric lens 30B has a quadratic curved surface shape that satisfies the relationship of Expression (2), and has a high degree of parallelism as in the case of the light source device 150A according to the first embodiment. It is possible to emit light. As in the present embodiment, the incident surface 3
If an aspheric lens 30B having curved surfaces having different shapes is used for 0Bi and the exit surface 30Bo, the manufacturing cost of the lens increases. However, in the light source device 150B of the present embodiment, the light reflected from the reflection surface 24R of the elliptical reflector is incident on the entrance surface 3A of the aspheric lens 30B.
In the aspheric lens 30B, the reflected light from the reflecting surface 24R of the elliptical reflector only changes the traveling direction once at the exit surface 30Bo in the aspheric lens 30B because the light is incident perpendicular to 0Bi. Therefore, the light source device 150B of the present embodiment is advantageous in that a light beam with higher parallelism can be obtained.

The shape of the rotational quadratic surface of the aspherical surface of the aspherical lens 30B in this embodiment is determined by the following method based on the equation (2).

First, the shape of the reflecting surface 24R of the elliptical reflector, the curvature of the entrance surface 30Bi of the aspherical lens 30B, and
The refractive index n of the aspherical lens 30B and the aspherical lens 30B
The value of the approximate curvature c is determined in consideration of the thickness of the central portion of the above and the installation position of the aspherical lens 30B. Specifically, the shape of the reflecting surface 24R and the incident surface 30B of the aspherical lens 30B
The curvature of i, the refractive index n of the aspherical lens 30B, the thickness of the central part of the aspherical lens 30B, and the installation position of the aspherical lens 30B are determined in advance. Then, for the elliptical reflector having the same shape as the predetermined shape of the reflecting surface 24R, the curvature of the incident surface, the refractive index, and the thickness of the central portion using a spherical concave lens at the predetermined position are used. , A curvature that can be converted into parallel light in a paraxial region (region near the rotation axis) is obtained. The value of the curvature obtained in this manner becomes the approximate curvature c.

Next, a conical constant K is obtained. Here, FIG.
As shown by a curve CB in FIG.
In B, the light source device 150 according to the first embodiment
Unlike the case A, even if the shape of the reflection surface 24R of the elliptical reflector is changed, the relationship between the refractive index n and the conical constant K of the aspheric lens 30B does not change. This is due to the difference between the shape (plane) of the incident surface 30Ai of the aspheric lens 30A shown in FIG. 3 and the shape (spherical surface) of the incident surface 30Bi of the aspheric lens 30B shown in FIG. That is, in the aspheric lens 30A shown in FIG. 3, since the incident surface 30Ai is a flat surface, the traveling direction of the reflected light from the reflecting surface 24R is changed by refraction at the incident surface 30Ai. On the other hand, in the aspheric lens 30B shown in FIG. 5, since the incident surface 30Bi is a spherical surface, the reflected light from the reflecting surface 24R enters the incident surface 30Bi so as to intersect substantially perpendicularly, and the traveling direction does not change.
As a result, in the curve CB, the reflection surface 24 of the elliptical reflector
Even if the shape of R is changed, the refractive index n of the aspherical lens 30B
And the conic constant K is constant. The conical constant K of the aspherical surface of the reflecting surface of the aspherical lens 30B shown in FIG.
Is substantially determined by K = −1 / n ² .

Therefore, in the present embodiment, the conic constant K can be obtained by K = −1 / n ² , and it is not necessary to perform the simulation as in the first embodiment.

Further, as can be seen from FIG. 6, in the light source device 150B of the present embodiment, the aspherical lens 30B
Has an aspherical conic constant K in the range of -0.55 <K <-0.3. Therefore, the light source device 150 of the present embodiment
When the entrance surface 30Bi of the aspheric lens 30B is a spherical surface and the exit surface 30Bo is an aspheric surface as in B, it is preferable that the aspheric surface has a spheroidal shape.

The light source device 150B according to this embodiment
Then, the light heading for the second focal point FR2 of the elliptical reflector is
The second focal point Fe of the aspherical surface of the aspherical lens 30B is not affected by the refraction at the entrance surface 30Bi of the aspherical lens 30B.
2 substantially coincides with the second focal point FR2 of the reflection surface 24R of the elliptical reflector.

As described above, in the light source device 150B according to the present embodiment, the shape of the aspherical surface of the exit surface 30Bo of the aspherical lens 30B is determined by using the expression (2) in which the third term on the left side of the expression (1) is ignored. By adopting a shape satisfying the relationship, that is, by adopting a quadratic curved surface shape, unlike the conventional light source device, light with high parallelism can be emitted. In the light source device 150B of the present embodiment, the light reflected from the reflecting surface 24R of the elliptical reflector is
Since the light is perpendicularly incident on the 0B incidence surface 30Bi, a light beam with higher parallelism can be obtained. Further, in the light source device 150B of the present embodiment, the aspherical lens 30B
Is preferably a spheroidal shape.

C. Light source device 150C: FIG. 7 is an explanatory diagram showing a light source device 150C according to the third embodiment of the present invention. FIG. 8 is an explanatory diagram showing a relationship between the reflection surface 24R of the elliptical reflector of the light source device 150C shown in FIG. 7 and the aspherical lens 30C. In the light source device 150A according to the first embodiment, the incident surface 30Ai of the aspheric lens 30A.
Are planes and the exit surface 30Ao is aspherical, but in the present embodiment, the entrance surface 30Ci of the aspherical lens 30C is aspherical, and the exit surface 30Co is planar. Since the configuration other than the aspheric lens 30C is the same as that of the light source device 150A according to the first embodiment, the same reference numerals as those used in FIGS. 1 to 3 are assigned, and the detailed description is omitted. I do.

In the light source device 150C according to the present embodiment, light rays emitted from the first focal point FR1 of the reflecting surface 24R of the elliptical reflector and reflected by the reflecting surface 24R travel in the direction of the second focal point FR2 of the reflecting surface 24R. , Aspheric lens 3
It is parallelized by 0C. In FIG. 8, Fh1 and Fh1
h2 is the first aspherical surface of the aspherical lens 30C, respectively.
Focus, second focus.

In the light source device 150C of the present embodiment,
The incident surface 30Ci of the aspheric lens 30C has a rotational quadratic curved surface shape that satisfies the relationship of Expression (2), and emits light with high parallelism as in the case of the light source device 150A according to the first embodiment. It is possible to inject.

As can be seen from a comparison between FIG. 7 and FIG. 2, the light source device 150A according to the first embodiment requires a smaller diameter of the emitted light beam than the light source device 150C according to the present embodiment. This is advantageous in that it can be performed. That is, the diameter 30ALD of the light beam emitted from the exit surface 30Ao of the aspheric lens 30A is equal to the incident surface 30Ao.
It becomes smaller than the diameter of the light beam incident on i. this is,
When the distance between the elliptical reflector and the aspherical lens 30A and the distance between the elliptical reflector and the aspherical lens 30C are set to be substantially the same, the aspherical lens 30 in FIG.
This is because the ray bundle of the reflected light on the exit surface 30Ao of the aspheric lens 30A in FIG. 2 is condensed and smaller than the ray bundle of the reflected light on the incident surface 30Ci of C. Therefore, the light source device 150 according to the first embodiment
If A is used for an illumination optical system or a projector as described later, the configuration of each part after the light source device can be reduced as a whole.

Further, the light source device 1 according to the first embodiment
50A is a light source device 150 according to the present embodiment, as can be seen from the distributions of the trajectories of the light rays shown in FIGS.
This is advantageous over C in that the illuminance distribution in the plane is emitted as a more uniform light beam. This is because the exit surface 30Ao is concave in the aspheric lens 30A in FIG. 2, and the incident surface 30Ci is concave in the aspheric lens 30C in FIG. That is, in the light source device 150A according to the first embodiment shown in FIG. 2, the incident angle of the light beam incident on the aspherical lens 30A is
There is not much difference between the center and the periphery of A. on the other hand,
In the light source device 150C according to the second embodiment shown in FIG. 7, the incident angle of the light beam incident on the aspherical lens 30C has a considerably large difference between the center and the periphery of the aspherical lens 30C. Therefore, in the light source device 150C, an intensity distribution is easily generated in the emitted light beam.

Further, the light source device 150A according to the first embodiment can reduce the manufacturing cost.
This is more advantageous than the light source device 150C of the present embodiment. In general, the production of the aspherical portion of an aspherical lens requires considerable precision, and the smaller the aspherical portion, the lower the cost of production. For this reason, the light source device 150A using the aspherical lens 30A having a small aspherical portion can be produced at lower cost, and can be said to be more practical.

However, the light source device 15 of this embodiment
0C has an advantage that a light beam with higher parallelism can be easily obtained as compared with the case where the light source device 150A according to the first embodiment is used. That is, the light beam emitted from the light source device 150A is incident on the incident surface 30 of the aspherical lens 30A.
Due to refraction between Ai and the exit surface 30Ao, the light is emitted through two changes in the traveling direction. On the other hand, the light source device 150
The light beam emitted from C is emitted only once by changing the traveling direction due to refraction at the entrance surface 30Ci of the aspheric lens 30C. Therefore, the light source device 150C
Is used, it becomes possible to obtain a light beam having a considerably high degree of parallelism. Therefore, when it is necessary to obtain a light beam with higher parallelism, it is better to use the light source device 150C of the present embodiment. The light source device 150B according to the second embodiment is the same in that a light beam with higher parallelism can be obtained, but the aspheric lens 30C of the light source device 150C according to the present embodiment has one surface which is flat. Therefore, the light source device 150C of the present embodiment is more advantageous in terms of manufacturing cost.

The shape of the rotational quadratic surface of the aspherical surface of the aspherical lens 30C in this embodiment is determined by the following method based on the equation (2).

First, the shape of the reflecting surface 24R of the elliptical reflector, the refractive index n of the aspherical lens 30C, the thickness of the central part of the aspherical lens 30C, and the installation position of the aspherical lens 30C are taken into consideration. Find the value of the curvature c. Specifically, the shape of the reflecting surface 24R, the refractive index n of the aspherical lens 30C, the thickness of the central part of the aspherical lens 30C, and the installation position of the aspherical lens 30C are determined in advance. And
When a concave lens having a spherical surface with the same refractive index and the same thickness at the center is used at a predetermined position with respect to an elliptical reflector having the same shape as the predetermined shape of the reflecting surface 24R, if there is no spherical aberration, it is parallel. Find the curvature that can be converted to light. The value of the curvature obtained in this manner becomes the approximate curvature c.

Next, a conical constant K is obtained. Here, FIG.
As shown by a curve CC in FIG.
In C, the light source device 150 according to the first embodiment
Unlike the case A, even if the shape of the reflecting surface 24R of the elliptical reflector is changed, the relationship between the refractive index n and the conical constant K of the aspheric lens 30C does not change. This is due to the difference between the shape (plane) of the incident surface 30Ai of the aspheric lens 30A shown in FIG. 3 and the shape (aspheric surface) of the incident surface 30Ci of the aspheric lens 30C shown in FIG. That is, in the aspherical lens 30A shown in FIG. 3, since the incident surface 30Ai is a flat surface, the reflected light from the reflecting surface 24R is refracted by the incident surface 30Ai so that the traveling direction is non-parallel to the optical axis 20ax. And further refracted at the exit surface 30Ao. On the other hand, in the aspheric lens 30C shown in FIG.
Since i is an aspheric surface set based on equation (2),
The reflected light from the reflecting surface 24R is changed in its traveling direction to a substantially parallel direction by refraction at the incident surface 30Ci, and
At 0Co, there is almost no refraction effect. As a result, in the curve CC, even if the shape of the reflecting surface 24R of the elliptical reflector is changed, the refractive index n and the conical constant K of the aspheric lens 30C are changed.
Is constant. The conical constant K of the aspherical surface of the reflecting surface of the aspherical lens 30C shown in FIG.
−n ² .

Therefore, in this embodiment, the conic constant K can be obtained by K = −n ² , and it is not necessary to perform the simulation as in the first embodiment.

Further, as can be seen from FIG. 9, in the light source device 150C of the present embodiment, the aspherical lens 30C
Has a range of −2.1 <K <−3.8. Therefore, the light source device 150C of the present embodiment
When the incident surface 30Ci is an aspherical surface as described above, it is preferable that the aspherical surface has a rotating hyperboloidal shape. 8, straight lines P and Q are asymptote of a rotational hyperbola (a rotational hyperbola constituting a part of the entrance surface 30Ci of the aspherical lens 30C), and a curve R shows another rotational hyperbola. Are all illustrated in order to make it easy to understand that the aspherical surface has the shape of a rotating hyperboloid.

The light source device 150C according to this embodiment
Then, the light heading for the second focal point FR2 of the elliptical reflector is
The light source optical axis 20a is formed on the incident surface 30Ci of the aspherical lens 30C.
x, and is not refracted by the exit surface 30Co, so that the second focal point F of the aspherical surface of the aspherical lens 30C.
h2 is the second focal point FR of the reflection surface 24R of the elliptical reflector.
Almost coincides with 2.

As described above, in the light source device 150C according to the present embodiment, the shape of the aspherical surface of the incident surface 30Ci of the aspherical lens 30C is determined by the expression (2) of the expression (1) ignoring the third term on the left side. By adopting a shape satisfying the relationship, that is, by adopting a quadratic curved surface shape, unlike the conventional light source device, light with high parallelism can be emitted. Further, in the light source device 150C of the present embodiment, the reflected light from the reflecting surface 24R of the elliptical reflector is
The light is made parallel to the light source optical axis 20ax by the incident surface 30Ci of 0C, and the light is not refracted by the exit surface 30Co, so that a light beam with higher parallelism can be obtained.
Further, in the light source device 150C of the present embodiment, the aspherical conical constant K of the aspherical lens 30C is preferably a rotational hyperboloid.

D. Light source device 150D: FIG. 10 is an explanatory view showing a modified example of the light source device 150C according to the third embodiment of the present invention shown in FIGS. In the light source device 150D according to the present embodiment, the aspheric lens 30D is provided at a position where the light reflected by the reflection surface 24R of the elliptical reflector is once collected at the second focal point FR2 and diverges. In the light source device 150D of the present embodiment, since the configuration other than the aspherical lens 30D is the same as the light source device 150A according to the first embodiment, the same reference numerals as those used in FIGS. And a detailed description thereof will be omitted.

In the light source device 150D according to the present embodiment, light rays emitted from the first focal point FR1 of the reflecting surface 24R of the elliptical reflector and reflected by the reflecting surface 24R are collected at the second focal point FR2 of the reflecting surface 24R. After that, the light is collimated by the aspheric lens 30D. The aspheric lens 30D is
The entrance surface 30Di is an aspheric convex surface, and the exit surface 30Do
Is a plane. In FIG. 10, Fh1, Fh2
Are the first focal point and the second focal point of the aspheric surface of the aspheric lens 30D, respectively.

In the light source device 150D of the present embodiment,
The entrance surface 30Di of the aspheric lens 30D has a rotational quadratic curved surface shape that satisfies the relationship of Expression (2), and emits light with high parallelism as in the case of the light source device 150C according to the third embodiment. It is possible to inject.

As can be seen from a comparison between FIG. 10 and FIG.
The light source device 150D according to the present embodiment is advantageous over the light source device 150C according to the third embodiment in that the diameter of the emitted light beam can be reduced. This is because the aspheric lens 30D can be arranged at a position where the light collected at the focal point FR2 does not diverge more than the opening area of the reflection surface 24R. Therefore, if the light source device 150D is used for an illumination optical system or a projector as described later, it is possible to reduce the size of the optical elements disposed after the light source device. Further, the light source device 150D according to the present embodiment is more advantageous than the light source device 150C according to the third embodiment in that the manufacturing cost can be reduced because the aspherical portion is small. However, the distance between the elliptical reflector and the aspherical lens 30D is
It becomes larger than the case of the light source device 150C according to the third embodiment.

The light source device 1 according to the first embodiment
When compared with 50A, the light source device 150D of the present embodiment
Is disadvantageous in that an intensity distribution is easily generated in the emitted light beam, and is advantageous in that it is easier to obtain a light beam with higher parallelism than the light source device 150A according to the first embodiment. What is the same as in the case of the light source device 150C according to the third embodiment. In addition, when compared with the light source device 150B according to the second embodiment, the light source device 150D according to the present embodiment is more advantageous in terms of manufacturing cost, and is different from the light source device 150C according to the third embodiment. The same is true.

The rotational quadratic surface shape of the aspherical surface of the aspherical lens 30D in the present embodiment is expressed by a third quadratic shape based on the equation (2).
Aspherical lens 3 of light source device 150C according to the embodiment of the present invention
It is determined by the same method as the shape of the aspherical surface of OC.

In the light source device 150D of this embodiment, as in the case of the light source device 150C, the aspherical lens 30
It is preferable that the conical constant K of the aspherical surface of D be a hyperboloid of revolution. Straight lines P and Q in FIG. 10 are asymptote of a rotation hyperbola (a rotation hyperbola constituting a part of the entrance surface 30Di of the aspherical lens 30D), and a curve R shows another rotation hyperbola. Are all illustrated in order to make it easy to understand that the aspherical surface has the shape of a rotating hyperboloid.

The light source device 150D according to the present embodiment
Then, the light heading for the second focal point FR2 of the elliptical reflector is
Because it is not refracted by the aspheric lens 30D,
The second focal point Fh2 of the aspheric surface of the aspheric lens 30D substantially coincides with the second focal point FR2 of the reflection surface 24R of the elliptical reflector.

As described above, in the light source device 150D according to the present embodiment, the shape of the aspherical surface of the entrance surface 30Di of the aspherical lens 30D is determined by the expression (2) of the expression (1) ignoring the third term on the left side. By adopting a shape satisfying the relationship, that is, by adopting a quadratic curved surface shape, unlike the conventional light source device, light with high parallelism can be emitted. Further, in the light source device 150D of the present embodiment, the reflected light from the reflecting surface 24R of the elliptical reflector is
Since the light is made parallel to the light source optical axis 20ax by the 0D incidence surface 30Di and is not refracted by the emission surface 30Do, the light beam with higher parallelism is similar to the light source device 150C according to the third embodiment. It is possible to obtain Further, in the light source device 150D of the present embodiment, the aspherical conical constant K of the aspherical lens 30D is preferably a rotational hyperboloid.

In this embodiment, the entrance surface 30Di of the aspherical lens is a convex surface, and the exit surface 30Do is a flat surface. Conversely, an aspherical lens having the entrance surface of the aspherical lens as a plane and the exit surface as a convex surface is used. It can also be used. In this case, the shape is determined by a method similar to the shape of the aspherical surface of the aspherical lens 30A of the light source device 150A according to the first embodiment. At this time, the focal point of the aspheric surface does not coincide with the second focal point FR2 of the reflection surface 24R of the elliptical reflector, as in the case of the first embodiment. Further, similarly to the case of the light source device 150B according to the second embodiment, the entrance surface of the aspheric lens may be a spherical concave surface, and the exit surface may be an aspheric convex surface. In this way, a light beam having higher parallelism can be obtained as in the case of the second embodiment. In this case, the shape of the concave surface is the elliptical reflector 24.
Should be a spherical surface centered on the second focal point FR2.

E. Illumination optical system: FIG.
It is the schematic block diagram which looked at the principal part of the illumination optical system which applied the light source device 150A which concerns on 1st Embodiment in planar view. The illumination optical system 100 shown in FIG. 11 is an illumination optical system suitable for a projector including an illumination area LA such as a liquid crystal panel described later.

The illumination optical system 100 includes a light source device 150
A, a first lens array 40, a second lens array 50, a polarization generating optical system 60, and a superimposing lens 70. Each optical element is arranged in this order along the system optical axis 100ax. However, among these optical elements, the light source device 150A and the first lens array 40
And the second lens array 50 are arranged with reference to the light source optical axis 20ax. The light source optical axis 20ax is shifted substantially parallel to the system optical axis 100ax, which is the central axis of the light beam emitted from the optical element after the polarization generating optical system 60, by a predetermined shift amount Dp in the x direction in the drawing. . This shift amount Dp will be described later.

The first lens array 40 divides the substantially parallel light emitted from the aspherical lens 30A into a plurality of partial light beams, and condenses each partial light beam in the vicinity of the second lens array 50. It has the function to do. Also,
The second lens array 50 has a function of aligning the central axes of the partial light beams emitted from the first lens array 40 so as to be substantially parallel to the system optical axis 100ax.

FIG. 12 is a perspective view showing the appearance of the first lens array 40. The first lens array 40 has a configuration in which first small lenses 42 having a substantially rectangular outline are arranged in a matrix of M rows and N columns. FIG.
Shows an example where M = 5 and N = 4. The outer shape of each first small lens 42 viewed from the z direction is usually the illumination area L
The shape is set to be substantially similar to the shape of A. For example, assuming a liquid crystal panel as the illumination area LA, the aspect ratio (the ratio between the horizontal and vertical dimensions) of the effective area of the image is 4: 3.
If so, the aspect ratio of the first small lens 42 is also set to 4: 3. The second lens array 50 in FIG. 11 is the same as the first small lens 42 of the first lens array 40.
, The second small lenses 52 are arranged in a matrix of M rows and N columns.

A plurality of (M × N) partial light beams divided by the first small lenses 42 of the first lens array 40 are positioned close to the second lens array 50 as shown in FIG. That is, the light is focused in the polarization generating optical system 60.

FIG. 13 is an explanatory view showing the polarization generating optical system 60. FIG. 13A is a perspective view of the polarization generating optical system 60, and FIG. 13B is a partial plan view thereof. The polarization generation optical system 60 includes a light shielding plate 62, a polarization beam splitter array 64, and a selective phase difference plate 66.

The polarization beam splitter array 64 corresponds to FIG.
As shown in FIG. 3A, a plurality of columnar light-transmitting plate members 64c each having a substantially parallelogram cross section are bonded to each other. The polarization separating film 64 is provided at the interface between the transparent plates 64c.
a and the reflective films 64b are formed alternately. Note that a dielectric multilayer film is used as the polarization separation film 64a.
Further, as the reflection film 64b, a dielectric multilayer film or a metal film such as aluminum is used.

The light shielding plate 62 includes a light shielding surface 62 b and an opening surface 62.
a are arranged in a stripe pattern. The light shielding plate 62 has a function of blocking a light beam incident on the light shielding surface 62b and passing the light beam incident on the opening surface 62a. The light-shielding surface 62b and the aperture surface 62a allow the partial light beam emitted from the second lens array 50 (FIG. 11) to enter only the polarization splitting film 64a of the polarization beam splitter array 64 and not to the reflection film 64b. It is arranged as follows. Specifically, as shown in FIG.
The center of the second aperture surface 62a is disposed so as to substantially coincide with the center of the polarization splitting film 64a of the polarization beam splitter array 64. The opening width of the opening surface 62a in the x direction is set substantially equal to the size Wp of the polarization separation film 64a in the x direction. At this time, the opening surface 62 of the light shielding plate 62
Almost all of the light beam that has passed through a enters only the polarization splitting film 64a and does not enter the reflection film 64b. In addition, as the light-shielding plate 62, a light-shielding film (for example, a chromium film,
An aluminum film, a dielectric multilayer film, or the like can be used. Further, a light-shielding flat plate such as an aluminum plate provided with an opening may be used.

Each partial light beam emitted from the second lens array 50 (FIG. 11) has its principal ray (center axis) as shown by a solid line in FIG.
Incident on the opening surface 62a of the light shielding plate 62 almost in parallel with The partial light beam that has passed through the aperture surface 62a is
Incident on. The polarization splitting film 64a separates the incident partial light beam into an s-polarized light beam and a p-polarized light beam. At this time, the partial light beam of the p-polarized light is
, And the s-polarized partial light beam is reflected by the polarization splitting film 64a. The s-polarized partial light beam reflected by the polarization separation film 64a is directed to the reflection film 64b, and is further reflected by the reflection film 64b. At this time, the p-polarized partial light beam transmitted through the polarization splitting film 64a and the s-polarized partial light beam reflected by the reflective film 64b are substantially parallel to each other.

The selective phase difference plate 66 is provided between the opening layer 66a and the λ /
It is composed of two retardation layers 66b. The opening layer 66a is a portion where the λ / 2 retardation layer 66b is not formed. The aperture layer 66a has a function of transmitting incident linearly polarized light as it is. On the other hand, the λ / 2 retardation layer 66b has a function as a polarization conversion element that converts incident linearly polarized light into linearly polarized light having a polarization direction orthogonal to the polarization direction. In the present embodiment, as shown in FIG. 13B, the p-polarized partial light beam transmitted through the polarization separation film 64a enters the λ / 2 phase difference layer 66b. Therefore,
The p-polarized partial light beam is converted into an s-polarized partial light beam in the λ / 2 retardation layer 66b and emitted. On the other hand, the s-polarized partial light beam reflected by the reflection film 64b is
Since it is incident on the aperture layer 66a, it is emitted as a s-polarized partial light beam. That is, most of the non-polarized partial light beam incident on the polarization generating optical system 60 is converted into an s-polarized partial light beam and emitted. By arranging the λ / 2 phase difference layer 66b only on the exit surface of the s-polarized partial light beam reflected by the reflection film 64b, most of the partial light beam incident on the polarization generation optical system 60 can be converted into p-polarized light. It can also be converted into a partial light beam and emitted. Also,
The selective retardation plate 66 is such that nothing is provided in the portion of the opening layer 66a, and the λ / 2 retardation layer 66b is simply attached to the exit surface of the p-polarized partial light beam or the s-polarized partial light beam. It may be.

As can be seen from FIG. 13B, the center of the two s-polarized lights emitted from the polarization generating optical system 60 is larger than the center of the incident non-polarized light (s-polarized light + p-polarized light). It is shifted in the x direction. This shift amount is determined by the width Wp of the λ / 2 retardation layer 66b (ie, x of the polarization separation film 64a).
Direction size). Therefore, as shown in FIG. 11, the light source optical axis 20ax and the system optical axis 100ax
Is set at a position shifted by a distance Dp equal to Wp / 2.

As described above, the plurality of partial light beams emitted from the second lens array 50 are
As a result, each partial light beam is separated into two partial light beams, and is converted into almost one type of linearly polarized light having the same polarization direction.

A plurality of partial light beams having substantially the same polarization direction are applied to the illumination area LA by the superposition lens 70 shown in FIG.
Superimposed on As can be understood from the above description, the first lens array 40, the second lens array 50, and the superimposing lens 70 constitute a so-called integrator optical system. Thereby, it is possible to make the intensity distribution of the light applied to the illumination area LA substantially uniform.

The light source device 150A of this embodiment can emit substantially parallel light, as described below. Therefore, in the illumination optical system 100 of FIG. 11, the second lens array 50 and the light shielding plate 62 having the function of correcting or removing light with poor parallelism may be omitted.

As described above, the light source device 150A
Can emit light with high parallelism. Therefore,
In the illumination optical system 100 of the present embodiment, it is possible to improve the light use efficiency. The same effect can be obtained when the light source devices 150B to 150D are used in place of the light source device 150A in the illumination optical system 100 as described above.

The illumination optical system 100 of the present embodiment includes a uniform illumination optical system constituted by the lens arrays 40 and 50 and the superimposing lens 70, and a polarization generating optical system 60. However, the light source devices 150A to 150D Alternatively, they may be used alone without being combined with a uniform illumination optical system or a polarization generating optical system. Also, the light source devices 150A to 150A
D can form an illumination optical system in combination with only the uniform illumination optical system. That is, the light source devices 150A-
150D can also be applied to an illumination optical system that does not include the polarization generation optical system 60.

F. Projector: FIG. 14 is a schematic configuration diagram of a main part of a projector using the illumination optical system 100 of FIG. The projector 1000 includes an illumination optical system 100, a color light separation optical system 200, a relay optical system 220, and three liquid crystal light valves 300R and 300.
G, 300B, cross dichroic prism 320
And a projection optical system 340. Illumination optical system 10
The light emitted from 0 is separated by the color light separation optical system 200 into three color lights of red (R), green (G), and blue (B). Each of the separated color lights is a liquid crystal light valve 300R,
In 300G and 300B, modulation is performed in accordance with image information. The modulated color lights are combined by the cross dichroic prism 320, and an image is projected and displayed on the screen SC by the projection optical system 340.

As described with reference to FIG. 1, the illumination optical system 100 emits linearly-polarized light (s-polarized light) whose polarization direction is aligned, and outputs the liquid crystal light valve corresponding to the illumination area LA in FIG. Illuminate 300R, 300G, 300B. Liquid crystal light valves 300R, 300G, 300 of the present embodiment
B includes a liquid crystal panel corresponding to the electro-optical device of the present invention, and polarizing plates disposed on the light incident surface side and the light exit surface side, respectively. The polarizing plate disposed on each light incident surface side of the liquid crystal panel is for increasing the degree of polarization of the illumination light, and the polarization direction of the linearly polarized light emitted from the illumination optical system 100 is transmitted through the polarizing plate. It is arranged so as to coincide with the axial direction.

The color light separation optical system 200 includes two dichroic mirrors 202 and 204 and a reflection mirror 208, and converts a light beam emitted from the illumination optical system 100 into three colors of red, green and blue. It has the function of separating into color light.
The first dichroic mirror 202 is connected to the illumination optical system 10.
While transmitting the red light component of the light emitted from 0, it reflects the blue light component and the green light component. The red light R transmitted through the first dichroic mirror 202 is reflected by the reflection mirror 208 and emitted toward the cross dichroic prism 320. The red light R emitted from the color light separation optical system 200 reaches the liquid crystal light valve 300R for red light through the field lens 232. The field lens 232 converts each partial light beam emitted from the illumination optical system 100 into a light beam parallel to its central axis. The same applies to the field lenses 234 and 230 provided in front of the other liquid crystal light valves.

Of the blue light B and the green light G reflected by the first dichroic mirror 202, the green light G is reflected by the second dichroic mirror 204 and passes from the color light separation optical system 200 to the cross dichroic prism 32.
Injected toward zero. The green light G emitted from the color light separation optical system 200 reaches the liquid crystal light valve 300G for green light through the field lens 234. On the other hand, the blue light B transmitted through the second dichroic mirror 204
Are emitted from the color light separation optical system 200 and enter the relay optical system 220.

The blue light B incident on the relay optical system 220
Is the incident side lens 22 provided in the relay optical system 220.
2. Relay lens 226 and reflection mirrors 224, 22
8 and the exit side lens (field lens) 230 to reach the liquid crystal light valve 300B for blue light. The reason why the relay optical system 220 is used for the blue light B is that the optical path length of the blue light B is longer than the optical path lengths of the other color lights. The blue light B incident on the side lens 222 can be transmitted to the emission side lens 230 as it is.

Three liquid crystal light valves 300R, 300
G and 300B have a function as light modulating means for forming an image by modulating the three color lights in accordance with the given image information (image signal). The cross dichroic prism 320 includes the liquid crystal light valves 300R, 300
It has a function as a color light combining optical system for forming a color image by combining three color lights modulated through G and 300B. In the cross dichroic prism 320, a red light reflecting dichroic surface 321 and a blue light reflecting dichroic surface 322 are formed in an approximately X-shape at the interface between the four right-angle prisms. A dielectric multilayer film that reflects red light is formed on the red light reflecting dichroic surface 321. On the blue light reflecting dichroic surface 322, a dielectric multilayer film that reflects blue light is formed.
The three color lights are combined by the red light reflecting dichroic surface 321 and the blue light reflecting dichroic surface 322 to form combined light for projecting a color image.

The synthesized light generated by the cross dichroic prism 320 is emitted in the direction of the projection optical system 340. The projection optical system 340 projects the combined light emitted from the cross dichroic prism 320 and displays a color image on the screen SC. The projection optical system 34
As 0, a telecentric lens can be used.

In the projector 1000, the illumination optical system 100 uses a light source device 150A that can emit a light beam with high parallelism. Thus, the light use efficiency of the projector 1000 can be improved, so that a brighter image can be displayed. The same effect can be obtained when the light source devices 150B to 150D are used instead of the light source device 150A.

Note that the projector 1000 of the present embodiment
In the illumination optical system 100, the lens arrays 40 and 50
And a uniform illumination optical system constituted by a superimposing lens 70 and a polarization generating optical system 60.
0A to 150D may be used alone without being combined with a uniform illumination optical system or a polarization generation optical system.
In addition, the light source devices 150A to 150D can constitute an illumination optical system in combination with only the uniform illumination optical system. That is, an illumination optical system that does not include the polarization generation optical system 60 can be applied to the projector 1000 of the present embodiment.

The present invention is not limited to the above examples and embodiments, but can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible. is there.

(1) The above light source devices 150A to 150D
In the embodiment, each of the aspheric lenses 30A to 30D is arranged at a position away from the opening surface of the elliptical reflector 24, but may be joined to the opening surface. FIG. 15 shows a light source device 15 in which an aspheric lens is joined to an opening surface of an elliptical reflector.
It is explanatory drawing which shows OC '. The light source device 150C ′ includes a discharge lamp 22, an elliptical reflector 24, and an aspheric lens 30C ′.
And Note that this light source device 150C ′ adjusts the aspherical shape of the aspherical lens 30C of the light source device 150C (FIGS. 7 and 8) according to the third embodiment, and deforms the peripheral portion to form an elliptical reflector. Are joined to the opening surface of the slab. By arranging the aspherical lens 30C ′ on the opening surface of the elliptical reflector 24 as described above, the light source device 150C ′ can be downsized,
The aspheric lens 30C ′ can function as a front glass of the light source device 150C ′.

Similarly, in the light source devices 150A and 150B according to the first and second embodiments, the aspheric lenses 30A and 30B may be joined to the opening surface of the elliptical reflector 24. However, in the case of joining the aspherical lens 30D to the opening surface of the elliptical reflector 24 in the light source device 150D according to the fourth embodiment, the size of the light source device becomes large, which is not very practical. That is, in general, when the aspherical surface of the aspherical lens is concave, the aspherical lens can be joined to the opening surface of the elliptical reflector 24.

(2) Further, the light source device 150C 'shown in FIG.
In this example, an ultraviolet reflecting film UR is formed on the exit surface 30C'o of the aspherical lens 30C '. At this time, the discharge lamp 2
2 is reflected by the ultraviolet reflection film UR and returns to the inside of the elliptical reflector 24.
It is possible to prevent ultraviolet light from being emitted from 0C '. As a result, for example, when the light source device 150C ′ is applied to the projector 1000, it is possible to prevent the liquid crystal light valve from being deteriorated by ultraviolet rays. Also,
In the light source device 150C ′, the ultraviolet light emitted from the discharge lamp 22 is emitted from the emission surface 30C′o of the aspheric lens 30C ′.
At a right angle to the ultraviolet reflective film UR formed on the substrate.
At this time, the ultraviolet light reflected by the ultraviolet reflection film UR enters the discharge lamp 22 along the same path. When the ultraviolet light enters the center 22c of the discharge lamp 22, the discharge lamp 22 emits light having a longer wavelength than the incident ultraviolet light. This makes it possible to improve the intensity of visible light emitted from the light source device 150C ′.

In FIG. 15, the ultraviolet reflecting film UR is formed on the aspherical lens 30C 'joined to the opening surface of the elliptical reflector 24. However, as shown in FIGS. The same applies to the case where the aspheric lens 30C is provided at a position distant from the opening surface of the lens.

Similarly, in the light source devices 150B and 150D according to the second and fourth embodiments, the aspherical lens 30
An ultraviolet reflective film may be formed on B and 30D. In the light source device 150B, the aspherical lens 30B
An ultraviolet reflection film may be formed on the incident surface 30Bi. In the light source device 150D, the aspheric lens 30D
An ultraviolet reflection film may be formed on the exit surface 30Do. At this time, as in the case of the light source device 150C ′ of FIG. 15, the ultraviolet light reflected by the ultraviolet reflection film enters the discharge lamp 22 along the same path, so that the intensity of visible light can be improved. is there. In general, it is sufficient that an ultraviolet reflecting film is formed on a surface of the entrance surface or the exit surface of the aspherical lens, on which the ultraviolet light emitted from the discharge lamp is incident substantially from the normal direction.

(3) In the illumination optical system 100 (FIG. 11), the first lens array 40 is provided independently, but the first lens array is provided on the exit surface of the aspherical lens. You may. That is, when the light source devices 150C and 150D according to the third or fourth embodiment are used as the light source device of the illumination optical system 100, the exit surfaces 30Co and 30Do of the aspheric lenses 30C and 30D are flat. Therefore, it is possible to provide the first lens array on the exit surface of the aspherical lens. At this time, as each small lens 42 of the first lens array 40 shown in FIG.
A plano-convex lens having a flat surface on the aspherical lens side may be used.

Note that the present invention can be similarly applied to a case where an aspheric lens is joined to an opening surface of an elliptical reflector as in a light source device 150C ′ shown in FIG. Thus, by providing a lens array on the exit surface of the aspherical lens,
The illumination optical system 100 can be reduced in size. The lens array may be formed directly on the exit surface of the aspherical lens, or may be joined to the exit surface.
When the lens array is formed directly on the exit surface of the aspherical lens, there is an advantage that the number of parts can be reduced.

(4) In the above projector, the case where the illumination optical system of the present invention is applied to a transmission type projector is described as an example, but the present invention can also be applied to a reflection type projector. . Here, the “transmission type” means that an electro-optical device as a light modulation unit is a type that transmits light, such as a transmission type liquid crystal panel,
The “reflection type” means that an electro-optical device as a light modulation unit, such as a reflection type liquid crystal panel, reflects light. In a reflection type projector, the cross dichroic prism is used as a color light separating means for separating light into three colors of red, green, and blue, and combines the modulated three colors of light again in the same direction. It is also used as a color light combining means that emits light to When the present invention is applied to a reflection type projector, almost the same effects as those of a transmission type projector can be obtained.

(5) In the above embodiment, the projector 1000 for displaying a color image is described as an example. However, the illumination optical system of the present invention can be applied to a projector for displaying a monochrome image. is there. In this case, the same effects as those of the projector can be obtained.

(6) In the above embodiment, the projector 1000 uses the liquid crystal panel as the electro-optical device, but is not limited to this. As the electro-optical device, generally, any device that modulates incident light in accordance with image information may be used, and a micromirror-type light modulator may be used. As the micromirror-type light modulation device, for example, a DMD (digital micromirror device) (a trademark of TI Corporation) can be used.

[Brief description of the drawings]

FIG. 1 is a light source device 150 according to a first embodiment of the present invention.
It is explanatory drawing which shows A.

FIG. 2 is an explanatory diagram showing a trajectory of light rays radially emitted from the center of a discharge lamp 22 in a light source device 150A.

FIG. 3 is an explanatory diagram showing a relationship between a reflection surface 24R of an elliptical reflector and an aspheric lens 30A in the light source device 150A.

FIG. 4 shows an aspherical lens 30 of the light source device 150A.
5 is a graph showing the relationship between the refractive index n of A and the conical constant K.

FIG. 5 shows a light source device 150 according to a second embodiment of the present invention.
13B is an explanatory diagram showing a relationship between the reflection surface 24R of the elliptical reflector and the aspherical lens 30B in B. FIG.

FIG. 6 shows an aspheric lens 30 of the light source device 150B.
5 is a graph showing a relationship between a refractive index n of B and a conical constant K.

FIG. 7 shows a light source device 150 according to a third embodiment of the present invention.
FIG. 3C is an explanatory diagram showing a trajectory of light rays radially emitted from the center of the discharge lamp 22 in C.

FIG. 8 is an explanatory diagram showing a relationship between a reflection surface 24R of an elliptical reflector and an aspheric lens 30C in the light source device 150C.

FIG. 9 shows an aspheric lens 30 of the light source device 150C.
6 is a graph showing the relationship between the refractive index n of C and the conical constant K.

FIG. 10 shows a light source device 15 according to a fourth embodiment of the present invention.
It is explanatory drawing which shows the relationship between the reflection surface 24R of the elliptical reflector and the aspherical lens 30D in 0D.

FIG. 11 shows an illumination optical system 10 to which a light source device 150A is applied.
FIG. 2 is a schematic configuration diagram of a main part of the No. 0 seen in plan.

FIG. 12 is a perspective view showing the appearance of the first lens array 40.

FIG. 13 is an explanatory diagram showing a polarization generation optical system 60.

14 is a schematic configuration diagram of a main part of a projector 1000 using the illumination optical system 100 of FIG. 11 as viewed in plan.

FIG. 15 is an explanatory diagram showing a light source device 150C ′ in which an aspheric lens is joined to an opening surface of an elliptical reflector.

[Explanation of symbols]

20ax: Light source optical axis 22: Discharge lamp 22c: Center of discharge lamp 24: Elliptical reflector 24R: Reflective surface 25: Light source lamp 30A, 30B, 30C, 30C ', 30D: Aspheric lens 40: First lens array 42: Small lens 50 ... Second lens array 52 ... Small lens 60 ... Polarization generating optical system 62 ... Light shielding plate 62a ... Opening surface 62b ... Light shielding surface 64 ... Polarization beam splitter array 64a ... Polarization separation film 64b ... Reflection film 64c ... Light transmission Plate material 66 ... Selection retardation plate 66a ... Opening layer 66b ... λ / 2 retardation layer 70 ... Superimposing lens 100 ... Illumination optical system 100ax ... System optical axis 150A, 150B, 150C, 150C ', 150D
... Light source device 200 ... Color light separation optical system 202,204 ... Dichroic mirror 208 ... Reflection mirror 220 ... Relay optical system 222 ... Incoming side lens 224,228 ... Reflection mirror 226 ... Relay lens 230 ... Outgoing side lens 230,232,234 ... Field lens 300R, 300G, 300B ... Liquid crystal light valve 320 ... Cross dichroic prism 321 ... Red light reflecting dichroic surface 322 ... Blue light reflecting dichroic surface 340 ... Projection optical system 1000 ... Projector LA ... Illumination area SC ... Screen UR ... Ultraviolet reflecting film

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // H04N 5/74 F21Y 101: 00

Claims (16)

[Claims] 1. A lens comprising: a discharge lamp; an elliptical reflector having a reflection surface for reflecting light emitted from the discharge lamp; and a lens for collimating the light reflected by the reflection surface. Is an aspheric lens having an aspheric surface having a quadratic curved surface on one of the incident surface and the exit surface. 2. The light source device according to claim 1, wherein the aspheric surface represents a coordinate value in an rθZ cylindrical coordinate system axially symmetric with respect to an optical axis having an origin at an intersection of the aspheric surface and the light source optical axis. When r and Z are set, paraxial curvature is set as c, and conic constant is set as K, A light source device characterized by having a shape represented by: 3. The light source device according to claim 1, wherein the aspheric surface is a concave surface. 4. The light source device according to claim 3, wherein the aspheric lens is joined to an opening surface of the elliptical reflector. 5. The light source device according to claim 1, wherein the aspheric surface is a convex surface. 6. The light source device according to claim 3, wherein the emission surface is the aspheric surface, and the aspheric surface has a spheroidal shape. 7. The light source device according to claim 6, wherein the aspheric surface has an origin at a point of intersection of the aspheric surface and a light source optical axis.
When the coordinate values in the rθZ cylindrical coordinate system with the light source optical axis being the Z axis and the axis orthogonal to the light source optical axis being the r axis are r and Z, the paraxial curvature is c, and the conic constant is K, Equation 2 The elliptical reflector has an rθZ cylindrical coordinate with an intersection at the intersection of the reflection surface and the light source optical axis as an origin, the light source optical axis as a Z axis, and an axis orthogonal to the light source optical axis as an r axis. When the coordinate values in the system are r _R and Z _R , the paraxial curvature is c _R , and the conic constant is K _R , A shape represented by a -0.8 <K _R <-0.5, the light source device. 8. The light source device according to claim 6, wherein the incident surface is a spherical surface. 9. The light source device according to claim 8, wherein the aspheric surface has an origin at an intersection of the aspheric surface and a light source optical axis.
The light source optical axis is the Z axis, the coordinate values in the rθZ cylindrical coordinate system with the axis orthogonal to the light source optical axis as the r axis are r and Z, the paraxial curvature is c, the conic constant is K, and the conic constant is K. Assuming that the refractive index is n, Light source device having a shape represented by 10. The light source device according to claim 8, wherein an ultraviolet reflecting film is formed on the incident surface of the aspherical lens. 11. The light source device according to claim 3, wherein the incident surface is the aspheric surface, and the aspheric surface has a shape of a rotating hyperboloid. 12. The light source device according to claim 11, wherein the aspheric surface has an origin at an intersection of the aspheric surface and a light source optical axis.
The light source optical axis is the Z axis, the coordinate values in the rθZ cylindrical coordinate system with the axis orthogonal to the light source optical axis as the r axis are r and Z, the paraxial curvature is c, the conic constant is K, and the conic constant is K. Assuming that the refractive index is n, Light source device having a shape represented by 13. The light source device according to claim 11, wherein the emission surface of the aspherical lens is a flat surface, and an ultraviolet reflective film is formed on the emission surface of the aspherical lens. , Light source device. 14. The light source device according to claim 1, a lens array that divides light emitted from the light source device into a plurality of partial light beams, and the part that is divided by the lens array. An illumination optical system, comprising: a superimposing lens that superimposes a light beam on an illumination area. 15. The light source device according to claim 11, wherein: a lens array that divides light emitted from the light source device into a plurality of partial light beams; and a light beam that is split by the lens array. A superimposing lens for superimposing on an illumination area, wherein the exit surface of the aspheric lens of the light source device is a flat surface, and the lens array is provided on the exit surface of the aspheric lens. Characteristic illumination optical system. 16. A light source device according to claim 1, further comprising: a light incident surface as an illumination area illuminated by the light source device, wherein incident light from the light source device is changed according to image information. A projector, comprising: an electro-optical device that performs modulation; and a projection optical system that projects light modulated by the electro-optical device.