JP2001021997A - Illumination optical system and projection display device using the same - Google Patents

Abstract

(57) [Problem] To provide a technique for preventing an image of a lens array from being formed on an illumination area. An illumination optical system includes a light source device that emits a substantially parallel light beam, and a lens array that includes a plurality of small lenses for dividing the light beam emitted from the light source device into a plurality of partial light beams. 140, and a superimposing lens 170 for superimposing a plurality of partial light beams emitted from the lens array on a predetermined illumination area. In this illumination optical system, with respect to the image formed by the superimposing lens 170, the center point LAc of the illumination area is set to a conjugate point at infinity. Therefore, the lens array 140 and the illumination area LA are not conjugate. With such a configuration, it is possible to prevent the image of the lens array from being formed on the illumination area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an illumination optical system and a projection display apparatus for projecting and displaying an image using the illumination optical system.

[0002]

2. Description of the Related Art In a projection display apparatus, 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 light is projected on a screen. To realize image display.

In a projection display device, it is preferable that the luminance distribution of an image projected and displayed is substantially uniform. For this reason, in a projection display device, a so-called integrator optical system that can irradiate a portion (illumination region) of a liquid crystal panel on which image light is formed with a substantially uniform intensity distribution is used as an illumination optical system. I have.

FIG. 1 is an explanatory diagram showing a main part of a conventional illumination optical system 900 constituting an integrator optical system of a projection display device. The illumination optical system 900 includes a light source device 92
0, two lens arrays 940 and 950, and a superimposing lens 970. Each optical element includes a light source device 92
The light source 920ax, which is the central axis of the substantially parallel light flux emitted from the light source 0, is disposed as a reference.

The light source device 920 includes a light source lamp 922, a reflector 924, and a parallelizing lens 926.
Light radially emitted from the light source lamp 922 is reflected by the reflector 924. Parallelizing lens 926
Converts the light reflected from the reflector 924 into substantially parallel light and emits the light.

The first lens array 940 includes the light source device 9
It has a function of dividing a substantially parallel light beam emitted from the light source 20 into a plurality of partial light beams. First lens array 94
0 has a plurality of small lenses 942 in the xy plane. The plurality of small lenses 942 of the first lens array 940
Are plano-convex lenses each having a spherical convex surface,
The external shape of each small lens 942 viewed from the z direction is set to a substantially rectangular shape similar to the shape of the illumination area LA.

[0007] The second lens array 950 converts the image of each small lens 942 of the first lens array 940 into an illumination area LA.
It has the function of imaging on top. That is, as can be seen from the trajectory of the light beam indicated by the broken line in the figure, the first lens array 940 and the illumination area LA are conjugate with respect to the second lens array 950. Each small lens 952 of the second lens array 950 is
It is provided corresponding to each of the 40 small lenses 942. The plurality of small lenses 952 of the second lens array 950 are plano-convex lenses each having a spherical convex surface, and the external shape of each small lens 952 viewed from the z direction is the small lens 942 of the first lens array 940. Is almost the same as

The superimposing lens 970 is a plano-convex lens having a spherical convex surface. The superimposing lens 970 is emitted from each small lens 942 of the first lens array 940,
Has a function of superimposing a plurality of partial light beams that have passed through the lens array 950 on the illumination area LA. If the integrator optical system as shown in FIG.
Even when the light intensity distribution of the substantially parallel light flux emitted from 0 is not uniform, it is possible to illuminate the illumination area LA with light having a substantially uniform light intensity distribution.

[0009] When the power of the superimposing lens 970 is relatively large (when the focal length L of the superimposing lens is relatively small), spherical aberration occurs, so that each small lens 942 of the first lens array 940 has In some cases, light passing through the center does not converge well on the center point LAc of the illumination area LA. Therefore, when the power of the superimposing lens 970 is relatively large, the second lens array 950 in which the small lens 952 is decentered is used.

[0010]

As described above, the second lens array 950 forms the image of the first lens array 940 on the illumination area LA. Therefore, when dust adheres to the first lens array 940,
A dust image is formed on the illumination area LA. Also,
When the illumination optical system 900 is applied to a projection display device, a dust image is formed on the liquid crystal panel corresponding to the illumination area LA, so that the dust image is also included in the image displayed on the screen. The image quality is degraded. Such a problem is caused by the first lens array 940
This also occurs when a part of the antireflection film formed on the surface of the first lens array 940 has been peeled off, or when the boundaries between the small lenses of the first lens array 940 have an uneven shape.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and provides a technique for preventing an image of a first lens array from being formed on an illumination area. Aim.

[0012]

In order to solve at least a part of the above-described problems, a first apparatus of the present invention is an illumination optical system which emits a substantially parallel light beam. A light source device, a lens array including a plurality of small lenses for dividing the light beam emitted from the light source device into a plurality of partial light beams, and a plurality of partial light beams emitted from the lens array. And a superimposing lens for superimposing the illumination area on the illumination area, wherein the center point of the illumination area is a conjugate point at infinity with respect to the image formed by the superimposing lens.

In the illumination optical system according to the present invention, since the center point of the illumination area is set to a conjugate point at infinity with respect to the image formed by the superimposing lens, the lens array and the illumination area are not conjugate. Therefore, if such an illumination optical system is used, it is possible to illuminate the illumination area without forming an image of the lens array on the illumination area, and an image of dust or the like attached to the lens array on the screen. Image formation can be prevented. Therefore, a high-quality image can be obtained.

In the above-mentioned illumination optical system, it is preferable that the superimposing lens is an aspheric lens having a rotating quadric surface aspherical surface on one of an incident surface and an exit surface.

As described above, in the conventional illumination optical system, if the power of the superimposing lens is relatively large, the second
By decentering the small lenses of the lens array of
The partial ray bundle is successfully superimposed on the illumination area. However, in the illumination optical system of the present invention, the second lens array in the conventional illumination optical system is omitted. Therefore, in the illumination optical system of the present invention, an aspheric lens is used as the superimposing lens. In this case, even when the power of the superimposing lens is relatively large, it is possible to successfully superimpose the partial light beams that have passed through the small lenses of the lens array on the illumination area.

In the illumination optical system, it is preferable that the exit surface is the aspheric surface, and the aspheric surface has a shape of a rotating hyperboloid.

With this arrangement, even when the power of the superimposing lens is relatively large, the spherical aberration can be considerably reduced, so that the partial light beam from the lens array can be superimposed on the illumination area. .

In the above-mentioned illumination optical system, the entrance surface is a plane, and the shape of the hyperboloid of revolution of the exit surface is represented by Expression 3.

(Equation 3) Here, n is a refractive index of the superimposing lens, r and Z are coordinate values in a cylindrical coordinate system which is symmetrical with the optical axis with respect to the intersection point of the aspheric surface and the optical axis, and c is a predetermined constant. .

This makes it possible to easily determine the shape of the aspherical surface. In addition, this superimposed lens has an advantage that it can be manufactured relatively easily because the incident surface is flat.

Alternatively, in the illumination optical system, the incident surface may be the aspheric surface, and the aspheric surface may have a spheroidal shape.

[0021] Even in this case, similarly to the case where the exit surface of the superimposing lens is made aspherical, the partial light beam from the lens array can be successfully superimposed on the illumination area.

In the above-mentioned illumination optical system, the emission surface is a spherical surface having a center of curvature at the center point LAc of the illumination area LA, and the spheroidal shape of the entrance surface is expressed by the following equation (4).

(Equation 4) Here, n is a refractive index of the superimposing lens, r and Z are coordinate values in a cylindrical coordinate system which is symmetrical with the optical axis with respect to the intersection point of the aspheric surface and the optical axis, and c is a predetermined constant. .

In this way, the shape of the aspherical surface can be easily determined.

In the illumination optical system, the light source device may include a discharge lamp, an ellipsoidal reflector having a spheroidal reflection surface for reflecting light emitted from the discharge lamp, and light reflected by the reflection surface. A collimating lens for collimating the lens, wherein the collimating lens is an aspheric lens having a rotational quadratic curved aspheric surface on one of the incident surface and the exit surface. You may.

By using such a light source device, it is possible to emit a light beam having a considerably high degree of parallelism.

According to a second aspect of the present invention, there is provided a projection display apparatus, comprising: any one of the above-described illumination optical systems; and a light incident surface as the illumination area illuminated by the illumination optical system. It is preferable to include an electro-optical device that modulates illumination light from the illumination optical system according to image information to generate a modulated light beam, and a projection optical system that projects the modulated light beam.

As described above, when the above-mentioned illumination optical system is applied to the projection display device, the image of the lens array is not formed on the illumination area of the electro-optical device, so that the quality of the projected and displayed image is improved. It becomes possible.

[0028]

DETAILED DESCRIPTION OF THE INVENTION Illumination optical system: FIG. 2 is an explanatory diagram showing an illumination optical system 100 to which the present invention is applied. The illumination optical system 100 includes a light source device 120 and a lens array 14.
0 and a superimposing lens 170. Illumination optical system 1
Each of the optical elements 120, 140, and 170 is disposed with reference to a light source optical axis 120ax that is a central axis of a substantially parallel light beam emitted from the light source device 120. As shown, in the illumination optical system 100, two lens arrays 940, 9 used in the conventional illumination optical system 900 of FIG.
50, the second lens array 950 is omitted.

The light source device 120 includes a discharge lamp 122, a reflector 124, and a collimating lens 126. The reflector 124 is an elliptical reflector having a reflection surface 124R formed of a spheroid symmetrical to the light source optical axis 120ax. The spheroid is formed using, for example, glass. A dielectric multilayer film is formed on the reflection surface.
Note that a metal reflective film such as an aluminum film or a silver film may be formed on the reflective surface 124R.

The discharge lamp 122 emits light radially.
The center 122c of the discharge lamp 122 is
Of the two focal points on the light source optical axis 120ax, the focal point is closer to the elliptical reflector 124 (first focal point). Here, the center of the discharge lamp means the center of the arc generated between the electrodes of the discharge lamp. The radiated light emitted from the discharge lamp 122 is reflected by the elliptical reflector 1
The reflected light is reflected by the elliptical reflector 124.
Toward the other focal point (second focal point). As the discharge lamp 122, a metal halide lamp, a high-pressure mercury lamp, or the like is used.

The collimating lens 126 is an elliptical reflector 1
It has a function of converting the light reflected by the light 24 into substantially parallel light. The collimating lens 126 shown in FIG.
In the figure, the entrance surface 126i is a flat surface, and the exit surface 126o is an aspherical concave surface. By using such an aspheric lens as the collimating lens 126, the light source device 120 can emit a light beam with a considerably high degree of parallelism. The light source device 120 will be further described later.

The lens array 140 shown in FIG. 2 has a function of dividing a substantially parallel light beam emitted from the collimating lens 126 into a plurality of partial light beams. Lens array 140
Has a configuration in which a plurality of small lenses 142 are arranged in a matrix on an xy plane. The plurality of small lenses 142 of the lens array 140 are plano-convex lenses each having a spherical convex surface, and the outer shape of each small lens 142 viewed from the z direction is generally similar to the shape of the illumination area LA. It is set as follows. For example, assuming a liquid crystal panel as the illumination area LA, if the aspect ratio (ratio between the horizontal and vertical dimensions) of the effective display area of the liquid crystal panel is 4: 3, the aspect ratio of the small lens 142 is also 4: 3. Set. Note that the plurality of partial light beams split by the small lenses 142 of the lens array 140 are once collected near the superimposing lens 170 as shown in FIG.

The superimposing lens 170 includes a lens array 140
Has a function of superimposing a plurality of partial light beams divided by the illumination area LA on the illumination area LA. Thereby, it is possible to make the intensity distribution of the light applied to the illumination area LA substantially uniform. As can be seen from this description, the light source device 12
0, the lens array 140, and the superimposing lens 170,
This constitutes a so-called integrator optical system.

An aspheric lens is used as the superimposing lens 170 of the present embodiment. In the superimposing lens 170, the entrance surface 170i is a flat surface, and the exit surface 170o is an aspherical convex surface. Instead of the superimposing lens 170 having an aspherical convex surface, a conventional superimposing lens 970 (FIG. 1) having a spherical convex surface may be used. However, if the power of the superimposing lens is relatively large,
In other words, when the focal length L of the superimposing lens is relatively small, using a superimposing lens having a spherical convex surface causes spherical aberration. That is, the light source optical axis 120ax
After passing through the superimposing lens having a spherical convex surface, the parallel light passing through the vicinity is condensed on the center point LAc of the illumination area LA, but the parallel light passing through a position away from the light source optical axis 120ax is Light is condensed at a position shifted in the −z direction from the center point LAc. In such a case, there is a problem that a plurality of partial light beam bundles cannot be superimposed on the illumination area LA. In order to avoid this problem, in the conventional illumination optical system 900 (FIG. 1), the second lens array 94
An eccentric lens is used as a small lens arranged in the peripheral portion of the zero. However, in the illumination optical system 100 (FIG. 2) of the present embodiment, as described above, the second lens array 940 is omitted. Therefore, in the present embodiment, when the power of the superimposing lens 170 is relatively large, an aspheric lens is used as the superimposing lens 170. By using such a superimposing lens 170,
Each partial light beam split by the lens array 140 can be superimposed on the illumination area LA.

FIG. 3 is an explanatory diagram showing the relationship between the lens array 140, the superimposing lens 170, and the illumination area LA. In FIG. 3, each small lens 142 of the lens array 140 is shown.
Is shown only the trajectory of a ray passing through the center of. As shown, the light passing through the center of each small lens 142 of the lens array 140 is perpendicularly incident on the incident surface 170i of the superimposing lens 170, so that the incident light travels straight through the superimposing lens 170. The light that has reached the exit surface 170o of the superimposing lens 170 is refracted at the exit surface 170o and proceeds toward the center point LAc of the illumination area LA.

In the illumination optical system 100, regarding the image formation of the superimposing lens 170, the center point LAc of the illumination area LA
Has conjugate point at infinity. Therefore, unlike the conventional illumination optical system 900 (FIG. 1), the lens array 140 and the illumination area LA are not conjugate with respect to any of the imaging elements. Therefore, it is possible to avoid a problem that an image such as dust attached to the lens array 140 is formed on the illumination area LA.

The exit surface 17 of the superimposing lens 170
The aspherical surface of 0o is set so as to have a shape that almost satisfies the following Expression 5.

[0038]

(Equation 5)

Here, as shown in FIG. 3, r and Z are the intersections between the exit surface 170o (aspheric surface) of the superimposing lens 170 and the light source optical axis 120ax, the origin L0, and the light source optical axis 120a
x is a coordinate value in the rθZ cylindrical coordinate system that is symmetric about the axis.
In FIG. 3, the Z direction is positive in the −z direction. r indicates a distance from the origin L0 in a direction orthogonal to the light source optical axis 120ax. is an angle from the predetermined r direction, but as can be seen from Equation 5, the shape of the aspheric surface does not depend on the angle θ.

In equation (5), the paraxial curvature c is based on the assumption that parallel light incident on the superimposing lens 170 is condensed on the center point LAc of the illumination area LA using a plano-convex lens having a spherical convex surface. Shows the curvature of the spherical surface. In the paraxial region (region near the light source optical axis 120ax),
By using a plano-convex lens having this curvature c, parallel light incident on the plano-convex lens can be focused on the center point LAc of the illumination area.

K is a value called a conical constant. The aspheric surface is determined to have a specific shape by the value of the conical constant K. Specifically, when the value of the conic constant K is K <-1, the aspherical surface has a shape of a rotating hyperboloid. When the value of the conic constant K is -1 <K <0, the aspheric surface has a spheroidal shape, and when K = -1, the aspheric surface has a paraboloid of revolution.

The third term on the left side of Equation 5 is a function called a general aspherical term, which 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 superimposing lens 170 is determined on the basis of Equation 6 in which the third term on the left side of Equation 5 is ignored.

[0044]

(Equation 6)

Here, n indicates the refractive index of the superimposing lens 170.

The refractive index n of the superposition lens 170 is usually 1.
Since it is about 5 to 1.9, the conic constant K is K <−1. Therefore, the exit surface 170o of the superimposing lens 170
Is a hyperboloid of revolution. The exit surface 170o of the superimposing lens 170 designed as described above is a hyperboloid of revolution having the focal points at the two points FSh1 and FSh2 shown in FIG. Note that the focus FSh2 coincides with the center point LAc of the illumination area LA. In FIG. 3, two straight lines P and Q indicate asymptote lines of the two hyperbolas LH1 and LH2 shown.

Such an aspherical lens is connected to the superposition lens 17.
If 0 is used, even when the power of the superimposing lens 170 is relatively large, each partial light beam emitted from the lens array 140 can be successfully superimposed on the illumination area LA.

FIG. 4 is an explanatory view showing a modification of the superimposing lens. In FIG. 4, similarly to FIG.
And the relationship between the superimposing lens 172 and the illumination area LA. As the superimposing lens 172, an aspheric lens is used similarly to the superimposing lens 170 of FIG. 3, but the outer shape is different. That is, in the superimposing lens 172, the entrance surface 172i is an aspherical convex surface, and the exit surface 172o is a spherical concave surface. Light passing through the center of each small lens 142 of the lens array 140 is refracted on the incident surface 172i of the superimposing lens 172, and passes through the superimposing lens 172 to the center point LAc of the illumination area LA.
Continue toward. The emission surface 172o is a spherical surface centered on the center point LAc of the illumination area LA, as shown in FIG. At this time, the light refracted by the incident surface 172i is
Since the light is perpendicularly incident on the emission surface 172o, it proceeds toward the center point LAc of the illumination area LA as it is.

The aspherical surface of the entrance surface 172i of the superimposing lens 172 is set so as to have a shape substantially satisfying the following equation 7, similarly to the superimposing lens 170 of FIG.

[0050]

(Equation 7)

The Z direction is + z as shown in FIG.
The direction is positive.

Since the refractive index n of the superimposing lens 172 is usually about 1.5 to 1.9 as described above, the conic constant K
Is -1 <K <0. Therefore, the superimposing lens 17
The aspherical shape of the second incident surface 172i is a spheroidal shape. The incident surface 172i of the superimposing lens 172 designed in this manner is a spheroid having two points FSe1 and FSe2 shown in FIG. Note that the focal point FSe2
Coincides with the center point LAc of the illumination area LA.

Such an aspherical lens is connected to the superposition lens 17.
2, the same effect as that of the superimposing lens 170 of FIG. 3 can be obtained. That is, even when the power of the superimposing lens 172 is relatively large, each partial light beam emitted from the lens array 140 can be successfully superimposed on the illumination area LA. However, in the superimposing lens 170 of FIG. 3, since the incident surface 170i is a flat surface,
There is an advantage that the manufacture of the superposition lens is relatively easy.

The same effect can be obtained when this superimposing lens 172 is applied to the illumination optical system 100 shown in FIG. That is, since the lens array 140 and the illumination area LA are not conjugated with respect to any of the imaging elements, there is a problem that an image such as dust attached to the lens array 140 is formed on the illumination area LA. It is possible to avoid.

As can be seen from the above description, the superimposing lens in the present invention is generally an aspherical lens having a rotationally quadratic aspherical surface on one of the entrance surface and the exit surface. It is preferred that

B. Details of the light source device 120: FIG.
FIG. 4 is an explanatory diagram showing a light source device 120 of FIG. FIG. 5 shows the relationship between the reflecting surface 124R of the elliptical reflector in the light source device 120 and the parallelizing lens 126. The illustration of the discharge lamp is omitted, and only the center 122c of the discharge lamp is illustrated. The center 122c of the discharge lamp is located at the first focal point FR1 of the reflecting surface 124R as described above. The light emitted from the first focal point FR1 is reflected by the reflection surface 12
4R, the second focal point FR2 of the reflecting surface 124R
Head for. The light reflected by the reflection surface 124R and traveling while condensing enters the collimating lens 126.

As shown in FIG. 5, the collimating lens 126 has a plane of incidence 126i and a plane of emergence 126o aspherical spheroid. The aspherical shape of the exit surface 126o is set so as to substantially satisfy the following Expression 8, similarly to Expressions 6 and 7 representing the aspherical shapes of the superimposing lenses 170 and 172 (FIGS. 3 and 4). Have been.

[0058]

(Equation 8)

In Equation 8, r _P , Z _P , K _P , and C _P are the same as Equations 6 and 7, and a detailed description thereof will be omitted. Incidentally, Z _P direction is in the + z-direction and positive.

As shown in FIG. 5, the light passing through the collimating lens 126 is refracted not only by the aspheric surface of the exit surface 126o but also by the plane of the incident surface 126i. For this reason, the value of the conic constant K _P is
Like the conical constant K of 0,172 (Equation 6, Equation 7), it cannot be easily determined only by the refractive index n. Therefore,
The conical constant K _P of the collimating lens 126 is determined by the following method.

First, the reflecting surface 12 of the elliptical reflector 124
Set the shape of 4R. Thereby, the position of the second focal point FR2 to which the reflected light from the reflection surface 124R is directed is determined. Further, for the collimating lens 126, the curvature of the incident surface 126i, the refractive index n _P, and the thickness at the center are set. When the incident surface 126i of the parallelizing lens 126 is a flat surface as shown in FIG. 5, the curvature of the incident surface 126i is zero.
Should be set. Next, the position where the parallelizing lens 126 is installed, in other words, the positional relationship between the elliptical reflector 124 and the parallelizing lens 126 is set, and the parallelizing lens 126 is set.
Using the various values set above for paraxial curvature c
_Find the value of _P. The paraxial curvature c _P is determined by the collimating lens 126
Has a curvature such that light in the paraxial region can be converted into parallel light, assuming that the exit surface 126o has a spherical concave surface.

Next, a cone constant K _P is obtained. Conic constant K
_P is obtained by repeatedly performing a simulation using Expression 8 while changing its value (set value). Specifically, when the light beam emitted from the collimating lens 126 is condensed by an ideal lens having no aberration, the set value when the light spot diameter at the light condensing point becomes the smallest is set to the conic constant K _P. What is necessary is just to determine as a value.

The emission surface 126o determined as described above
Has a spheroidal shape, and two points Fe in FIG.
1. Focus on Fe2. At this time, light traveling from the reflection surface 124R toward the second focal point FR2 is reflected by the parallelizing lens 1
26 is refracted at the entrance surface 126i and exit surface 126o
Proceeds toward the second focal point Fe2 of the spheroid. The light that has reached the emission surface 126o is refracted again at the emission surface 126o, and is emitted as light parallel to the light source optical axis 120ax. By using the light source device 120 provided with the parallelizing lens 126 designed in this way, it is possible to emit a light beam with considerably high parallelism.

In the light source device 120 shown in FIG. 5, the second focal point Fe2 of the aspheric surface of the collimating lens 126 does not coincide with the second focal point FR2 of the reflecting surface 124R of the elliptical reflector. This is because, as described above, the second
This is because the light traveling toward the focal point FR2 undergoes a refraction action on the incident surface 126i of the collimating lens 126. If the incident surface 126i of the parallelizing lens 126 is a spherical surface centered on the second focal point FR2 of the reflecting surface 124R, the reflecting surface 124R
Light traveling from R to the second focal point FR2 is refracted only by the aspheric surface of the collimating lens. Therefore,
If the incident surface 126i of the collimating lens 126 is a spherical surface,
Aspherical second focal point Fe2 and reflecting surface 12 of elliptical reflector
It is possible to match the second focus FR2 of 4R. At this time, the conic constant K _P in Equation 8 may be set to −1 / n _P ² . By using such a collimating lens,
It is possible to emit a light beam with higher parallelism.
However, the use of the parallelizing lens 126 having a flat entrance surface as shown in FIG. 5 has an advantage that the manufacturing of the parallelizing lens is easy.

The light source device used in the illumination optical system 100 is not limited to the light source device 120 shown in FIG. For example, the incident surface is an aspheric surface (concave surface) with a hyperboloid of revolution.
When a collimating lens having an emission surface as a plane is applied to the light source device, it is possible to emit a light beam with a considerably high degree of parallelism. In this case, also, the aspherical shape can be determined by using Expression 8 similar to the above. At this time, the conic constant K _P may be set to −n _P ² . Thus, as the light source device in the present invention, it is preferable to use an elliptical reflector and an aspheric lens having an aspheric surface having a quadratic curved surface on one of the incident surface and the exit surface.

As a light source device used in the illumination optical system 100, a parabolic reflector having a reflecting surface in the form of a rotating paraboloid may be used. Also in this case, it is possible to emit a light beam with high parallelism. As can be seen from the above description, the light source device of the present invention may be any device that generally emits a substantially parallel light beam.

C. Projection display device: FIG. 6 is an explanatory diagram showing a projection display device to which the illumination optical system of the present invention is applied. The projection display device 1000 includes an illumination optical system 100 ′.
A color light separation optical system 200, a relay optical system 220,
Three liquid crystal light valves 300R, 300G, 300B
, A cross dichroic prism 320, and a projection lens 340.

The light emitted from the illumination optical system 100 ′ (FIG. 6) is separated into three color lights of red (R), green (G), and blue (B) in the color light separation optical system 200. The separated color lights are supplied to the liquid crystal light valves 300R, 300G, 3
At 00B, modulation is performed according to 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 lens 340.

FIG. 7 is an explanatory diagram showing the illumination optical system 100 ′ of FIG. 6 in an enlarged manner. The illumination optical system 100 ′ is almost the same as the illumination optical system 100 shown in FIG. 2, except that a polarization generation optical system 60 is added to the illumination optical system 100. In FIG. 7, the same components as those in FIG. 2 are denoted by the same reference numerals.

In the illumination optical system 100 ', the light source device 120
And the lens array 140 are arranged with reference to the light source optical axis 120ax, and the polarization generating optical system 60 and the superimposing lens 170 are arranged with reference to the system optical axis 100'ax. The system optical axis 100'ax is the central axis of the light beam emitted from the optical element downstream of the polarization generating optical system 60, and the system optical axis 100'ax and the light source optical axis 120ax are shifted by a predetermined distance in the x direction. It is shifted substantially in parallel by the amount Dp. This shift amount Dp will be described later.

The substantially parallel light beam emitted from the light source device 120 is divided into a plurality of partial light beams by each small lens 142 of the lens array 140. Each partial light beam emitted from each small lens 142 is condensed in the polarization generating optical system 60 as shown in FIG.

FIG. 8 is an explanatory diagram showing the polarization generating optical system 60. FIG. 8A is a perspective view of the polarization generating optical system 60, and FIG. 8B is a part of a plan view when viewed from the + y direction. 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 (A), a plurality of columnar translucent plate members 64c each having a substantially parallelogram cross section are bonded to each other. The polarization separating film 64a
And the reflection film 64b are formed alternately. Note that a dielectric multilayer film is used as the polarization separation film 64a. Further, a dielectric multilayer film or a metal film is used as the reflection film 64b.

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 opening surface 62a are
40 (FIG. 7) is incident on only the polarization splitting film 64a of the polarization beam splitter array 64,
They are arranged so that they do not enter the reflection film 64b. Specifically, as shown in FIG. 8B, the center of the opening surface 62a of the light shielding plate 62 is arranged so as to substantially coincide with the center of the polarization separation film 64a of the polarization beam splitter array 64. The opening width Wp of the opening surface 62a in the x direction is
The size is set to be substantially equal to the size of the polarization separation film 64a in the x direction. At this time, almost all of the light beam that has passed through the opening surface 62a of the light-shielding plate 62 is incident only on the polarization separation film 64a, and is not incident on the reflection film 64b.
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) partially formed on a flat transparent body (for example, a glass plate) 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 lens array 140 (FIG. 7) has a principal ray (center axis) substantially parallel to the light source optical axis 120ax, as shown by a solid line in FIG. The light is incident on the opening surface 62a. The partial light beam that has passed through the aperture surface 62a enters the polarization splitting film 64a.
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 p-polarized partial light beam transmits through the polarization splitting film 64a,
The s-polarized partial light beam is reflected by the polarization splitting film 64a.
The s-polarized partial light beam reflected by the polarization splitting film 64a is
The light is further reflected by the reflection film 64b toward the reflection film 64b. At this time, the p-polarized partial light beam transmitted through the polarization separation 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 aperture 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 this embodiment, as shown in FIG. 8B, the p-polarized partial light beam transmitted through the polarization separation film 64a enters the λ / 2 phase difference layer 66b. Therefore, p
The partial beam of polarized light passes through the λ / 2 retardation layer 66b.
The light is converted into an s-polarized partial light beam and emitted. On the other hand, the s-polarized partial light beam reflected by the reflection film 64b is incident on the aperture layer 66a, and thus is emitted as the s-polarized partial light beam. That is, the unpolarized partial light beam incident on the polarization generating optical system 60 is converted into an s-polarized partial light beam and emitted. The λ / 2 retardation layer 66 is provided only on the exit surface of the s-polarized partial light beam reflected by the reflection film 64b.
By arranging b, the partial light beam incident on the polarization generating optical system 60 can be converted into a p-polarized light beam and emitted. The selective phase difference plate 66 includes an opening layer 66.
Nothing may be provided at the portion a, and the λ / 2 retardation layer 66b may simply be attached to the exit surface of the p-polarized partial light beam or the s-polarized partial light beam.

As can be seen from FIG. 8B, the center of the two s-polarized lights emitted from the polarization generating optical system 60 is + x more than the center of the incident unpolarized light (s-polarized light + p-polarized light).
It is shifted in the direction. The amount of this shift is determined by the λ / 2 retardation layer 66.
It is equal to half the width Wp of b (that is, the size of the polarization separation film 64a in the x direction). Therefore, as shown in FIG.
The light source optical axis 120ax and the system optical axis 100'ax are
It is shifted by a distance Dp equal to Wp / 2.

As described above, the plurality of partial light beams emitted from the lens array 140 are separated into two partial light beams for each partial light beam by the polarization generating optical system 60, and the polarization directions thereof are aligned. It is converted into almost one type of linearly polarized light. A plurality of partial light beams having the same polarization direction are illuminated by the superimposing lens 170 shown in FIG.
A is superimposed on A.

The illumination optical system 100 ′ (FIG. 6) emits illumination light of linearly polarized light (s-polarized light) having a uniform polarization direction, and outputs the liquid crystal through the color light separation optical system 200 and the relay optical system 220. The light valves 300R, 300G, and 300B are illuminated. In the projection display device, the liquid crystal light valves 300R, 300G, and 300B correspond to the illumination area LA in FIG.
Corresponding to

The color light separation optical system 200 includes two dichroic mirrors 202 and 204 and a reflection mirror 208, and converts the light beam emitted from the illumination optical system 100 ′ into three colors of red, green and blue. Has the function of separating the light into different colors.
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 has a function of converting 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 on the light incident surface side of the other liquid crystal light valves 300G and 300B.

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.

Blue light B incident on 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 R and G, and the relay optical system 220 is used. Thus, the blue light B incident on the incident side lens 222 can be transmitted to the exit side lens 230 as it is.

Three liquid crystal light valves 300R, 300
G and 300B modulate the incident three color lights, respectively, according to given image information (image signals) to generate a modulated light beam. The liquid crystal light valve 300R of the present embodiment,
Each of 300G and 300B is constituted by 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. The polarizing plate arranged on the light incident surface side of the liquid crystal panel,
This is for increasing the degree of polarization of the illumination light, and is arranged such that the polarization direction of the linearly polarized light emitted from the illumination optical system 100 'coincides with the transmission axis direction of the polarizing plate.

The cross dichroic prism 320 is
The three color lights (modulated light beams) modulated through the liquid crystal light valves 300R, 300G, and 300B are combined to generate combined light representing a color image. The cross dichroic prism 320 has a red light reflecting dichroic surface 32.
1 and a blue light reflecting dichroic surface 322 are formed in an approximately X-shape at the interface of the four right-angle prisms. A red light reflecting dichroic surface 321 has a dielectric multilayer film that reflects red light, and a blue light reflecting dichroic surface 322 has a dielectric multilayer film that reflects blue light. These red light reflecting dichroic surfaces 3
21 and the blue light reflecting dichroic surface 322 combine the three color lights to generate a combined light for projecting a color image.

The combined light generated by the cross dichroic prism 320 is emitted toward the projection lens 340. The projection lens 340 projects the combined light emitted from the cross dichroic prism 320 to display a color image on the screen SC. The projection lens 34
As 0, a telecentric lens can be used.

As described above, the projection display apparatus 1000 uses the illumination optical system 100 'shown in FIG. In the illumination optical system 100 ', since the second lens array in the conventional illumination optical system 900 (FIG. 1) is omitted, the lens array 140 and the illumination area LA
Neither imaging element is conjugate. Therefore, an image of dust or the like adhering to the lens array 140 may be applied to the liquid crystal light valves 300R, 300R corresponding to the illumination area LA.
No image is formed on G, 300B. This can prevent the image projected and displayed on the screen SC from including an image of dust or the like, thereby improving the quality of the displayed image.

In the projection display device 1000,
Instead of the illumination optical system 100 ', the illumination optical system 100 of FIG.
May be used. That is, the illumination optical system 100 without the polarization generation optical system 60 can be applied to the projection display apparatus 1000. However, the illumination optical system 10 of FIG.
When 0 ′ is used, the predetermined linearly polarized light emitted from the polarization generating optical system 60 can be made incident on the liquid crystal light valve, and thus there is an advantage that the light use efficiency can be improved.

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-described projection type display device is described by taking as an example the case where the illumination optical system of the present invention is applied to a transmission type projection type display device. However, the present invention is directed to a reflection type projection type display device. It is also possible to apply to. Here, “transmission type” means that an electro-optical device as a light modulating unit transmits light, such as a transmission type liquid crystal panel, and “reflection type” means a reflection type. This means that an electro-optical device as a light modulating unit, such as a liquid crystal panel, is of a type that reflects light. Even when the present invention is applied to a reflection type projection display device, almost the same effects as those of a transmission type projection display device can be obtained.

(2) In the above embodiment, the projection display apparatus 1000 for displaying a color image is described as an example. However, the illumination optical system of the present invention is applied to the projection display apparatus for displaying a monochrome image. It is also possible to apply. Also in this case, the same effects as those of the projection display device can be obtained.

(3) In the above embodiment, the projection type display apparatus 1000 shows an example in which a liquid crystal panel is used as an electro-optical device. However, the present invention 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 an explanatory diagram showing a main part of a conventional illumination optical system 900 constituting an integrator optical system of a projection display device.

FIG. 2 is an explanatory diagram showing an illumination optical system 100 to which the present invention is applied.

FIG. 3 is an explanatory diagram showing a relationship among a lens array 140, a superimposing lens 170, and an illumination area LA.

FIG. 4 is an explanatory diagram showing a modified example of the superimposing lens.

FIG. 5 is an explanatory diagram showing the light source device 120 of FIG.

FIG. 6 is an explanatory diagram showing a projection display device to which the illumination optical system of the present invention is applied.

FIG. 7 is an explanatory diagram showing the illumination optical system 100 ′ of FIG. 6 in an enlarged manner.

FIG. 8 is an explanatory diagram showing a polarization generation optical system 60.

[Explanation of symbols]

 Reference numeral 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: each translucent plate 64c: translucent plate 66: selective position Phase difference plate 66a: Opening layer 66b: λ / 2 phase difference layer 100: Illumination optical system 100 ': Illumination optical system 100'ax: System optical axis 120: Light source device 120ax: Light source optical axis 122: Discharge lamp 122c: Discharge lamp Center 124 ... Elliptical reflector 124R ... Reflective surface 126 ... Collimating lens 126i ... Parallizing lens incident surface 126o ... Parallizing lens emitting surface 140 ... Lens array 142 ... Small lens 170,172 ... Superimposed lens 170i, 172i ... Superimposed lens , Incident surfaces 170o, 172o ... exit surfaces of the superimposing lenses 200 ... color light separation optical systems 202, 204 ... Echroic mirror 208 ... Reflection mirror 220 ... Relay optical system 222 ... Incoming side lens 224,228 ... Reflection mirror 226 ... Relay 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 lens 900, illumination optical system 920, light source device 920 ax, light source optical axis 922, light source lamp 924, reflector 926, collimating lens 940, first lens array 942: small lens 950: second lens array 952: small lens 970: superimposed lens 1000: projection display device LA: illumination area LAc: center point of illumination area SC: screen

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02F 1/13357 G09F 9/00 360K 5C060 G09F 9/00 360 13/04 U 5C096 13/04 H04N 5/74 A 5G435 H04N 5/74 9/31 C 9/31 G02F 1/1335 530 F term (reference) 2H052 BA02 BA03 BA09 BA14 2H087 KA06 KA07 KA29 LA24 RA04 RA12 RA13 2H088 EA15 HA12 HA13 HA14 HA15 HA20 HA21 HA25 HA28 MA06 2H091 FA02Z FA05Z FAZ FA08 FA08Z FA17Z FA26Z FA29Z FA34Z FA43Z FB08 FD13 LA07 LA15 5C058 EA00 EA11 EA12 5C060 BC01 GB01 GB05 GB10 HC01 HC09 HC19 HC21 HC25 JA05 5C096 AA00 BA05 CB10 CC08 CE02 CG01 CG07 CG17 CH11 C0213 DD01 GG03 DD01 GG08 GG28 HH02 LL15

Claims (8)

[Claims] 1. An illumination optical system, comprising: a light source device for emitting a substantially parallel light beam; and a plurality of small lenses for dividing the light beam emitted from the light source device into a plurality of partial light beams. A lens array including: a lens array including: a plurality of partial light beams emitted from the lens array; and a superimposing lens configured to superimpose the plurality of partial light beams on a predetermined illumination area. An illumination optical system characterized in that a distant point is a conjugate point. 2. The illumination optical system according to claim 1, wherein the superimposing lens is an aspheric lens having a rotational quadric surface aspheric surface on one of an incident surface and an exit surface. , Illumination optics. 3. The illumination optical system according to claim 2, wherein the exit surface is the aspheric surface, and the aspheric surface has a shape of a rotating hyperboloid. 4. The illumination optical system according to claim 3, wherein the incident surface is a flat surface, and the shape of the hyperboloid of revolution of the exit surface is represented by Expression 1. (Equation 1) Here, n is a refractive index of the superimposing lens, r and Z are coordinate values in a cylindrical coordinate system which is symmetrical with the optical axis with respect to the intersection point of the aspheric surface and the optical axis, and c is a predetermined constant. . 5. The illumination optical system according to claim 2, wherein the entrance surface is the aspheric surface, and the aspheric surface has a spheroidal shape. 6. The illumination optical system according to claim 5, wherein the exit surface is a spherical surface, and the shape of the spheroid of the entrance surface is represented by Expression 2. (Equation 2) Here, n is a refractive index of the superimposing lens, r and Z are coordinate values in a cylindrical coordinate system which is symmetrical with the optical axis with respect to the intersection point of the aspheric surface and the optical axis, and c is a predetermined constant. . 7. The illumination optical system according to claim 1, wherein the light source device includes: a discharge lamp; and a spheroidal reflecting surface configured to reflect light emitted from the discharge lamp. An elliptical reflector having: and a collimating lens for collimating the light reflected by the reflecting surface, wherein the collimating lens is rotated secondary to one of the incident surface and the exit surface. An illumination optical system, which is an aspheric lens having a curved aspheric surface. 8. An illumination optical system according to claim 1, further comprising: a light incident surface serving as the illumination area illuminated by the illumination optical system, wherein illumination light from the illumination optical system is imaged. A projection display apparatus comprising: an electro-optical device that modulates according to information to generate a modulated light beam; and a projection optical system that projects the modulated light beam.