JP2003090981A - Illumination optical system and projector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently illuminate the specified illumination area of a liquid crystal light valve or the like even when a 1st lens array of an illumination optical system includes small lenses formed at different positions along an optical axis direction. SOLUTION: This illumination optical system for illuminating the specified illumination area is equipped with a light source device, the 1st lens array having a plurality of 1st small lenses for dividing the bundle of rays emitted from the light source device into a plurality of partial bundles of rays, and a 2nd lens array arranged near a position where a plurality of partial bundles of rays emitted from the 1st lens array are condensed and having a plurality of 2nd small lenses corresponding to the plurality of 1st small lenses. At least a part of the plurality of 1st small lenses is provided so that the position in the optical axis direction of the illumination optical system is different. The 2nd small lenses are provided so that their distances from the 1st small lenses to which the 2nd small lenses respectively correspond are nearly equal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector for projecting and displaying an image, and more particularly to an illumination optical system for making the intensity distribution of light illuminating an illumination area substantially uniform.

[0002]

2. Description of the Related Art In a projector, light emitted from an illumination optical system is modulated by a liquid crystal light valve or the like according to image information (image signal), and the modulated light is projected on a screen to display an image. To be done.

The illumination optical system usually includes a light source device, first and second lens arrays, and a superimposing lens. The light beam bundle emitted from the light source device is divided into a plurality of partial light beam bundles by the plurality of small lenses provided in the first lens array. The plurality of partial ray bundles are superimposed on the liquid crystal light valve by the superimposing lens after passing through the second lens array including the plurality of small lenses corresponding to the plurality of small lenses of the first lens array. By using such an illumination optical system, the intensity distribution of the light that illuminates the liquid crystal light valve can be made substantially uniform.

The irradiation area formed by each partial light flux on the liquid crystal light valve is an enlarged image of each small lens of the first lens array. Then, this enlargement ratio is substantially determined according to the distance between the first and second lens arrays and the distance between the superimposing lens and the liquid crystal light valve.

[0005]

By the way, when a decentering lens is used as a small lens of the first lens array, the first lens array is placed at different positions along the optical axis direction of the illumination optical system. It may include a formed lenslet. However, when the first lens array includes small lenses formed at different positions along the optical axis direction, each partial ray bundle emitted from each small lens forms on the liquid crystal light valve. The size of the irradiation area is different, and the illumination optical system may not be able to efficiently illuminate the liquid crystal light valve.

The present invention has been made in order to solve the above-mentioned problems in the prior art, and the first lens array of the illumination optical system has small lenses formed at different positions along the optical axis direction. An object of the present invention is to provide a technique capable of efficiently illuminating a predetermined illumination area such as a liquid crystal light valve even when it is included.

[0007]

In order to solve at least a part of the above-mentioned problems, the first device of the present invention is an illumination optical system for illuminating a predetermined illumination area. A light source device, and a plurality of first light beam devices for dividing the light beam bundle emitted from the light source device into a plurality of partial light beam bundles.
A first lens array having small lenses and a plurality of plurality of partial light beams, which are arranged in the vicinity of a position where a plurality of partial ray bundles emitted from the first lens array are condensed, and which correspond to the plurality of first small lenses. A second lens array having a second small lens, wherein at least some of the plurality of first small lenses are provided so as to have different positions along the optical axis direction of the illumination optical system. The plurality of second small lenses are provided such that the distances between the corresponding second small lenses are substantially equal to each other.

In this specification, the "position" of the small lens means the position of the apex of the curved surface of the small lens. The “distance” between the two lenses means the distance between the vertices of the curved surfaces of the two lenses.

According to the above-mentioned illumination optical system, the magnification of the image of each small lens of the first lens array on the predetermined illumination area becomes substantially constant. As a result, the size of the irradiation area formed by the partial ray bundles emitted from the respective small lenses of the first lens array on the predetermined illumination area can be made substantially equal to each other, so that the illumination optical system can efficiently perform the illumination area. It becomes possible to illuminate.

In the illumination optical system, the plurality of first
At least a part of the small lenses is an eccentric lens, and the position of the first small lenses arranged in a predetermined direction among the plurality of first small lenses is from the center side of the first lens array. You may make it change monotonously along the said optical axis direction toward the outer peripheral side.

Here, at the boundary between two adjacent first small lenses arranged in the predetermined direction, the curved surfaces of the two adjacent first small lenses may be formed to be continuous with each other. preferable.

As described above, when the curved surfaces of the two first small lenses are formed so as to be continuous with each other at the boundary between the two first small lenses, a plane shape is formed at the boundary between the two first small lenses. The first lens array can be manufactured easily and accurately as compared with the case of forming the side wall.

The plurality of first small lenses and the plurality of second small lenses are formed so that their curved surfaces are opposite to each other along the optical axis direction, and the predetermined directions are the same. It is preferable that the thicknesses of the first and second small lenses arranged in 1 are monotonically changed from the center side of the first and second lens arrays toward the outer peripheral side.

In this way, the surface of the first lens array opposite to the surface on which the curved surface of each small lens is formed can be made the same plane, and each small lens of the second lens array can be made. Since the surface opposite to the surface on which the curved surface is formed can be made the same plane, the first lens array and the second lens array can be manufactured relatively easily.

In the present specification, the "thickness" of the small lens means the maximum distance between the entrance surface and the exit surface of the small lens.

Further, the plurality of first small lenses and the plurality of second small lenses each have a curved entrance surface side and a flat exit surface side, and among the plurality of first small lenses, the predetermined number. The position of the plane on the exit surface side of the first small lenses arranged in the direction may monotonously change along the optical axis direction from the center side to the outer peripheral side of the first lens array. preferable.

Alternatively, the plurality of first small lenses and the plurality of second small lenses each have a flat incident surface side and a curved exit surface side, and among the plurality of second small lenses, the predetermined one. The position of the plane on the incident surface side of the second small lenses arranged in the direction is monotonically changed along the optical axis direction from the center side to the outer peripheral side of the second lens array. May be.

With this configuration, it is possible to form the first small lenses and the corresponding second small lenses so that the distance between them is substantially equal.

In the above illumination optical system, the second
A superimposing lens for superimposing the plurality of partial light beam bundles emitted from the lens array on the predetermined illumination area may be provided.

A second device of the present invention is a projector for projecting and displaying an image, which is an electro-optical device for modulating any of the above-mentioned illumination optical system and light from the illumination optical system according to image information. And a projection optical system for projecting the modulated light obtained by the electro-optical device.

Since this projector uses the above-mentioned illumination optical system, the illumination optical system can efficiently illuminate the electro-optical device corresponding to a predetermined illumination area.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described based on examples. FIG. 1 is a schematic configuration diagram showing an example of a projector to which the present invention is applied. Projector 1
000 is an illumination optical system 100 and a color light separation optical system 200
, Relay optical system 220, and three liquid crystal light valves 3
00R, 300G, 300B, a cross dichroic prism 320, and a projection optical system 340.

The light emitted from the illumination optical system 100 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 modulated in the liquid crystal light valves 300R, 300G and 300B according to the image information. Here, each of the liquid crystal light valves 300R, 300G, and 300B is composed of a liquid crystal panel corresponding to the electro-optical device in the present invention, and polarizing plates arranged on the light incident surface side and the light emitting surface side thereof. A drive unit (not shown) for supplying image information to the liquid crystal panel to drive the liquid crystal panel is connected to each liquid crystal light valve. Liquid crystal light valve 300R,
The modulated ray bundles modulated according to the image information in 300G and 300B are cross dichroic prism 320.
Screen SC by the projection optical system 340.
Projected on. As a result, the image is displayed on the screen SC. Regarding the configuration and function of each part of the projector as shown in FIG. 1, for example,
JP-A-10-32595 disclosed by the applicant of the present application
Since it is described in detail in Japanese Patent Publication No. 4, the detailed description is omitted in this specification.

FIG. 2 is an enlarged view of the illumination optical system 100 shown in FIG. The illumination optical system 100 includes a light source device 120 and first and second lens arrays 140, 1
50, a polarization generating optical system 160, and a superimposing lens 170. Each optical component has a system optical axis 100ax
It is arranged based on. Where the system optical axis 1
00ax is the central axis of the light beam emitted from the light source device 120. Note that, in FIG. 2, the illumination area LA illuminated by the illumination optical system 100 is the liquid crystal light valve 30 of FIG.
It corresponds to 0R, 300G, and 300B.

The light source device 120 comprises a lamp 122, a reflector 124 having a spheroidal concave surface, and a collimating lens 126. The lamp 122 is arranged near the first focus on the spheroid of the reflector 124. The light emitted from the lamp 122 is reflected by the reflector 12
The reflected light is reflected by 4, and the reflected light travels while being collected toward the second focus of the reflector 124. Collimating lens 12
Reference numeral 6 converts incident condensed light into light substantially parallel to the system optical axis 100ax.

The light source device 120 further includes an ultraviolet ray removing filter 1 provided on the light incident surface side of the collimating lens 126.
25 are provided. The ultraviolet removal filter 125 is a filter for removing ultraviolet light from the light emitted from the lamp 122 of the light source device 120. As a result, it is possible to reduce the deterioration of an optical component using an organic material (for example, a polarizing plate included in a liquid crystal light valve) due to ultraviolet rays. Instead of the ultraviolet removing filter 125, an ultraviolet removing film may be formed on the light emitting surface of the collimating lens 126.

As the light source device 120, a reflector having a concave paraboloidal surface may be used. In this case, the light reflected by the reflector is the system optical axis 1
Since it is almost parallel to 00ax, the collimating lens 126 can be omitted.

First and second lens arrays 140, 1
50 has a plurality of small lenses 142 and 152, respectively. The first lens array 140 includes the light source device 120.
It has a function of splitting a substantially parallel light flux emitted from the light source into a plurality of partial light fluxes and emitting them. Then, in the second lens array 150, the central axes of the partial ray bundles emitted from the first lens array 140 are set to the system optical axis 1
It has a function of aligning with almost parallel to 00ax. Also,
The second lens array 150 has a function of forming an image of each small lens 142 of the first lens array 140 on the illumination area LA together with the superimposing lens 170.

Each of the small lenses 142 and 152 is a plano-convex decentering lens, and the external shape when viewed from the x direction is set to be substantially similar to the illumination area LA (liquid crystal light valve). . However, as shown in FIG. 2, the first small lens 142 and the second small lens 152 use decentering lenses that are different in decentering method. Specifically, the outermost small lens 14 of the first lens array 140.
2, the principal ray of the divided partial ray bundle is the system optical axis 1
It is eccentric so as to move obliquely with respect to 00ax. In addition, the outermost small lens 15 of the second lens array 150.
Reference numeral 2 is decentered so that the principal ray of the partial ray bundle that is obliquely incident on the system optical axis 100ax is substantially parallel to the system optical axis 100ax.

Each small lens 1 of the first lens array 140
The partial ray bundle emitted from 42 is, as shown in FIG.
The light is focused through each small lens 152 of the second lens array 150, in the vicinity thereof, that is, in the polarization generation optical system 160.

Incidentally, the first and second lens arrays 14
Details of 0 and 150 will be described later.

The polarized light generating optical system 160 is an integrated optical system.
Two polarization generating element arrays 160A and 160B are provided. First and second polarization generating element arrays 160A, 1
60B is arranged symmetrically with respect to the system optical axis 100ax.

FIG. 3 is an enlarged view of the first polarization generating element array 160A shown in FIG. FIG. 3 (A) shows
FIG. 3B is a perspective view of the first polarization generating element array 160A, and FIG. 3B is a plan view as seen from the + z direction. The polarization generating element array 160A includes the light shielding plate 16
2, a polarization beam splitter array 164, and a plurality of λ / 2 phase difference plates 166 selectively arranged on the light exit surface of the polarization beam splitter array 164. The same applies to the second polarization generating element array 160B.

As shown in FIGS. 3A and 3B, the polarization beam splitter array 164 is formed by laminating a plurality of columnar glass materials 164c having a substantially parallelogram cross-sectional shape. Polarization separation films 164a and reflection films 164b are alternately formed on the interface of each glass material 164c. A dielectric multilayer film is used as the polarization separation film 164a, and a dielectric multilayer film or a metal film is used as the reflection film 164b.

The light shielding plate 162 is formed by arranging an opening surface 162a and a light shielding surface 162b in a stripe pattern. The opening surface 162a and the light shielding surface 162b are provided corresponding to the polarization separation film 164a and the reflection film 164b, respectively. As a result, the partial light flux emitted from the first lens array 140 (FIG. 2) passes through the opening surface 162a and the polarization separation film 1 of the polarization beam splitter array 164.
It enters only 64a and does not enter the reflecting film 164b.
As the light blocking plate 162, a plate-shaped transparent body (eg, glass plate) on which a light blocking film (eg, chrome film, aluminum film, dielectric multilayer film, etc.) is selectively formed can be used. . It is also possible to use a light-shielding flat plate such as an aluminum plate provided with a striped opening. Further, a light blocking film may be directly formed on the glass material 164c of the polarization beam splitter array 164.

The principal ray (center axis) of each partial ray bundle emitted from the first lens array 140 (FIG. 2) is shown in FIG.
As shown by the solid line in FIG. 3B, the light enters the opening surface 162a of the light shielding plate 162 substantially parallel to the system optical axis 100ax.
The partial light flux that has passed through the opening surface 162a is reflected by the polarization separation film 1
At 64a, the s-polarized partial light bundle and the p-polarized partial light bundle are separated. The s-polarized light is the polarization separation film 16
It is assumed that the polarization direction is perpendicular to the incident surface of 4a and the p-polarized light is the polarization direction parallel to the incident surface of the polarization separation film 164a. The p-polarized partial light flux passes through the polarization separation film 164a and is emitted from the polarization beam splitter array 164. On the other hand, the s-polarized partial light beam bundle is reflected by the polarization separation film 164a, further reflected by the reflection film 164b, and then emitted from the polarization beam splitter array 164. On the light exit surface of the polarization beam splitter array 164, the principal ray of the p-polarized partial ray bundle and the principal ray of the s-polarized partial ray bundle are substantially parallel to each other.

The λ / 2 retardation plate 166 is the polarization separation film 16 of the light exit surface of the polarization beam splitter array 164.
It is formed only on the light exit surface of the p-polarized partial ray bundle that has passed through 4a. The λ / 2 retardation plate 166 has a function of converting incident linearly polarized light into linearly polarized light whose polarization directions are orthogonal to each other. Therefore, the p-polarized partial ray bundle is
The λ / 2 retardation plate 166 converts the partial light flux of s-polarized light and outputs it. As a result, the partial light flux (s + p) that is incident on the polarization generating element array 160A and has no bias
Is converted into an s-polarized partial ray bundle and emitted. Note that λ / is present only on the light exit surface of the s-polarized partial ray bundle.
By disposing the two-phase retarder 166, it is also possible to convert the partial light beam bundle that enters the polarization generating element array 160A into a p-polarized partial light beam bundle and emit the partial light beam bundle.

The plurality of partial ray bundles emitted from the first lens array 140 are, as described above, the polarization generating optical system 1.
Each of the partial light ray bundles is separated into two partial light ray bundles by 60, and is converted into almost one type of linearly polarized light having the same polarization direction. A plurality of partial light fluxes having the same polarization direction are superimposed on the illumination area LA by the superimposing lens 170 shown in FIG. At this time, the intensity distribution of the light illuminating the illumination area LA is substantially uniform.

As described above, the illumination optical system 100 (FIG. 1)
Emits illumination light whose polarization direction is uniform (s-polarized light) and illuminates the liquid crystal light valves 300R, 300G, and 300B via the color light separation optical system 200 and the relay optical system 220.

The illumination optical system 100 is characterized by the configuration of the first lens array 140 and the second lens array 150.

FIG. 4 shows the first lens array 140 of FIG.
It is explanatory drawing which expands and shows. FIG. 4A is a plan view of the first lens array 140 seen from the −x direction. 4B is a schematic cross-sectional view taken along the line BB of FIG. 4A, and FIG. 4C is a schematic cross-sectional view taken along the line C-C of FIG. 4A.

The first lens array 140 includes a total of 48 small lenses 142 of the same size. Each small lens 142 is a substantially rectangular lens having sides parallel to the y-direction and the z-direction, and the outer shapes when viewed from the x-direction are substantially the same. The small lenses 142 are arranged so as to be line-symmetric with respect to the y-axis and the z-axis that are orthogonal to the system optical axis 100ax.

As shown in FIG. 4A, the outer shape of each small lens is substantially determined according to the aspect ratio (aspect ratio) of the effective display area of the liquid crystal light valve. That is, if the aspect ratio of the effective display area is 3: 4, the aspect ratio of the outer shape of each small lens is also 3: 4.

As described above, the first lens array 14
A decentering lens is used as each small lens 142 of 0. In this embodiment, as shown in FIG. 4C, the positions of the small lenses arranged in the y direction are the first.
The lens array 140 is sequentially shifted from the center side to the outer peripheral side toward the −x side along the system optical axis 100ax. The “position” of the small lens means the position of the apex of the curved surface of the small lens.

By the way, the position of each small lens 142 of the first lens array 140 is different for the following reason. FIG. 5 is an explanatory view showing a schematic cross section of various lens arrays in which the respective small lenses are arranged similarly to FIG. Note that FIG. 5C is the same as FIG. 4C and shows a schematic cross section of the lens array 140.

In the lens array 140A of FIG. 5 (A),
A decentering lens is used as each small lens 142A. In this lens array 140A, the positions of the six small lenses 142A arranged in the y direction are slightly different from each other, but the positions of the six small lenses 142A arranged in the y direction are substantially the same along the system optical axis 100ax. have. Then, a planar side wall substantially parallel to the system optical axis (that is, the central axis of the incident ray bundle) 100ax is formed at the boundary between two adjacent small lenses arranged in the y direction. This lens array 140A is shown in FIG.
If the first lens array 140 is used in place of the first lens array 140, there are the following problems. That is, it is relatively difficult to make the lens array 140A of FIG.
In fact, as in the lens array 140B shown in FIG. 5B, the tip of the planar side wall formed at the boundary between two adjacent small lenses 142B is often rounded. Then, when the lens array 140B of FIG. 5B is used in place of the first lens array 140 of FIG. 4, each small lens 142B causes the light incident on the rounded region W to be the second lens. It cannot be fired well towards the array 150 (FIG. 2). Therefore, each small lens 1
The size of the irradiation region formed on the liquid crystal light valve by each partial light flux emitted from 42B becomes smaller as the size of the region W becomes larger.

In the lens array 140 of this embodiment shown in FIG. 5C, the above planar wall surface is not formed at the boundary between two adjacent small lenses 142 arranged in the y direction. There is. Specifically, two small lenses 1
The boundary of 42 is connected so that the curved surfaces of two adjacent small lenses are continuous. When the lens array 140 of FIG. 5C is used, each small lens 142 can successfully emit all the incident light toward the second lens array 150. As described above, when the curved surfaces of the two first small lenses 142 are formed so as to be continuous with each other so that a flat wall surface is not formed at the boundary between the two first small lenses 142, two First small lens 1
The first lens array can be manufactured easily and accurately as compared with the case where a flat wall surface is formed at the boundary of 42.

For the above reasons, the first lens array 14
When an eccentric lens is used for each small lens 142 of 0, the position of each small lens 142 has a different position along the system optical axis direction.

FIG. 6 shows the first lens array 140 and the second lens array 140.
It is explanatory drawing which shows the relationship with the lens array of. Figure 6
FIG. 6A shows a schematic plan view of the first and second lens arrays 140 and 150 in the example as seen from the + z direction, and FIG. 6B shows the first and second lens arrays in the comparative example. 2 is a schematic plan view of the lens arrays 140 and 150A of FIG. Since the first and second lens arrays are configured symmetrically with respect to the system optical axis 100ax, the system optical axis 1 is shown in FIG.
Only the + y direction side is shown with respect to 00ax. Also,
The first and second lens arrays are formed using materials having the same refractive index.

As shown in FIG. 6A, the second lens array 150 has small lenses 152 corresponding to the small lenses 142 of the first lens array 140. As shown in FIG. 2, the first small lens 142 and the second small lens 152 use decentering lenses that are different in decentering method. Specifically, the first lens array 1
The outermost lenslet 142c of 40 is decentered so that the principal ray of the divided partial ray bundle advances obliquely with respect to the system optical axis 100ax. Further, the outermost small lens 152c of the second lens array 150 is the system optical axis 1
The principal ray of the partial ray bundle that is obliquely incident on 00ax is decentered so as to be substantially parallel to the system optical axis 100ax.

Each small lens 1 of the first lens array 140
The curved surface of 42 faces the −x direction, and the second lens array 15
The curved surface of each small lens 152 of 0 faces the + x direction.

The position of the first small lenses 142 arranged in the y direction of the first lens array 140 changes monotonously from the central side of the first lens array 140 toward the outer peripheral side, and accordingly the position of the first small lenses 142 changes monotonously. The positions of the second small lenses 152 arranged in the y direction of the second lens array 150 also change monotonously from the center side of the second lens array 150 toward the outer peripheral side. On the other hand, the first lens array 14
The surface of each small lens 142 of 0 opposite to the curved surface constitutes the same plane. The same applies to the second lens array 150. Therefore, the thickness of the first small lenses 142 arranged in the y direction of the first lens array 140 changes monotonically from the center side of the first lens array 140 toward the outer peripheral side, and the thickness of the second lenslets 140 increases. The thickness of the second small lenses 152 arranged in the y direction of the lens array 150 also monotonically changes from the center side of the second lens array 150 toward the outer peripheral side. The [thickness] of the small lens means the maximum distance between the incident surface and the exit surface of the small lens.

Each small lens 1 of the second lens array 150
52 are provided so that the distances between the corresponding small lenses 142 of the first lens array 140 are equal. Specifically, with respect to the innermost small lens 142a of the first lens array 140, the outer small lens 142a is disposed.
The positions of b and 142c are in the -x direction (system optical axis 100a
They are provided at positions displaced by lengths Δtb and Δtc in the direction (along x). Then, the second lens array 150
The positions of the outer small lenses 152b and 152c with respect to the innermost small lens 152a are also shifted by the lengths Δtb and Δtc in the −x direction (direction along the system optical axis 100ax). There is. That is, each distance between the first small lens 142 and the corresponding second small lens 152 is equal to the distance S1 between the innermost first small lens 142a and the second small lens 152a. It is provided in.

On the other hand, as shown in FIG. 6B, each small lens 152A of the second lens array 150A of the comparative example is
It is provided at the same position in the x direction regardless of the position of the corresponding small lens 142 of the first lens array 140.
Therefore, the distance between the first small lens 142b and the second small lens 152Ab in the middle is the distance S between the first small lens 142a and the second small lens 152Aa at the innermost circumference.
1, the length is increased by Δtb. Further, the distance between the first small lens 142c and the second small lens 152Ac at the outermost circumference is longer than the distance S1 by the length Δtc.

When the first and second lens arrays 140 and 150 shown in FIG. 6A are used, the following effects can be obtained.

FIG. 7 is an explanatory diagram showing the magnification of the image of the small lens 142 of the first lens array 140.
FIG. 7 shows the first lens array 1 for ease of explanation.
40 small lenses 142, a corresponding small lens 152 of the second lens array 150, and a superimposing lens 170 are arranged on the system optical axis 100ax.
It shows a case where the deflection of light by each lens is ignored.
Further, although a field lens or the like is usually provided in the previous stage of the illumination area LA as shown in FIG. 1, such a lens is also ignored.

In FIG. 7, S1 is the first small lens 1
The second small lens 152 from the vertex (object point O) of the curved surface 42.
Is the distance to the apex of the curved surface of the superimposing lens 1
The distance from the vertex of the curved surface 70 to the illumination area LA (image point O ′) is shown. Focal length f of second small lens 152
1 is set equal to the distance S1. The focal length f2 of the superimposing lens 170 is set equal to the distance S2. When considering the above field lens, the combined focal length of the superimposing lens 170 and the field lens is used as the focal length f2.

H1 represents the height at which the light emitted from the object point O on the optical axis cuts the curved surface of the second small lens 152, and u1
Indicates the inclination angle (= h1 / S1) of the light. Further, h2 represents the height at which the light emitted from the object point O on the optical axis cuts the curved surface of the superimposing lens 170, and u2 represents the inclination angle (= h2 / S2) of the light.

Y1 is the first small lens 1 at the object point O
42 shows the size of the image of 42 in the y direction, and y2 shows the size of the magnified image of the first small lens 142 at the image point O ′.

Magnification magnification β of the image of the first small lens 142
Is represented as follows: β≡y2 / y1 = u1 / u2 = (h1 / S1) / (h2 / S2) = S2 / S1 = f2 / f1 (1)

As can be seen from the above equation (1), the magnification magnification β of the image of the first small lens 142 is determined by the distances S1 and S2.

Here, as shown in FIG. 6B, in the first and second lens arrays 140 and 150A of the comparative example, the first small lens 142 and the second small lens 15 are included.
Since the distance between the first small lens 142 and 2A differs depending on the displacement of the position of the first small lens 142, the magnification of the image of the first small lens 142 formed on the illumination area LA changes. .

On the other hand, as shown in FIG. 6A, in the first and second lens arrays 140 and 150 of this embodiment, the first small lens 142 and the second small lens 152 are included.
Since the distances between and are equal,
The magnification of the image of each first small lens 142 formed on the illumination area LA (liquid crystal light valve) is set to be substantially constant.

Therefore, in the illumination optical system 100 using the first and second lens arrays 140 and 150 of the present embodiment, each small lens 142 of the first lens array 140.
Since the size of the irradiation area formed on the illumination area LA (liquid crystal light valve) by the partial ray bundles emitted from can be made substantially the same, the illumination area can be efficiently illuminated.

As described above, the illumination optical system 100 of this embodiment includes the light source device 120 and a plurality of first small light fluxes for splitting the light beam bundle emitted from the light source device 120 into a plurality of partial light beam bundles. The first lens array 140 having the lens 142 and a plurality of first lens arrays 140 corresponding to the plurality of first small lenses 142 are disposed in the vicinity of the positions where the plurality of partial ray bundles emitted from the first lens array are condensed. 2 small lenses 152
And a superimposing lens 170 for superimposing a plurality of partial light beam bundles emitted from the second lens array 150 on a predetermined illumination area LA. Then, at least a part of the plurality of first small lenses 142 is in the optical axis direction of the illumination optical system (system optical axis 1
00ax) are formed at different positions. In addition, the plurality of second small lenses 152 are configured such that the distances between the corresponding second small lenses 152 are substantially equal to each other. Such first and second
If the lens arrays 140 and 150 of No. 1 are used, the size of the irradiation area formed in the illumination area LA by the partial ray bundles emitted from the respective small lenses of the first lens array can be made substantially the same, so that the illumination optical system Illumination area LA
It is possible to efficiently illuminate the (liquid crystal light valve).

As described above, also in the lens array 140A of FIG. 5A, the lens array 1 of the embodiment is used.
Although the thickness is smaller than that of 40, the position of each small lens 142A may have a different position along the system optical axis direction. Even if the lens array 140A is to be used as the first lens array, the illumination area LA (liquid crystal light valve) can be efficiently illuminated by applying the present invention.

By the way, in the present embodiment, the second lens array 150 uses a decentering lens as the second small lens 152, similarly to the first lens array 140. Therefore, there is a problem similar to that described with reference to FIG. 5B, that is, a problem that a tip end portion of a planar side wall formed at a boundary between two adjacent second small lenses 152 is rounded. Can occur. However, since each partial ray bundle emitted from the first lens array 140 only enters a part of each small lens 152 of the second lens array 150, the above problem is caused by the second lens array 150. Does not significantly affect the optical characteristics. Therefore, the second lens array 150 does not necessarily have to be devised so that the above-mentioned planar wall surface is not formed at the boundary between two adjacent small lenses 152 arranged in the y direction.

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

(1) The first and second lens arrays are
The curved surface of each small lens 142 of the first lens array 140 may face the + x direction, and the curved surface of each small lens 152 of the second lens array 150 may face the −x direction. That is, the curved surfaces may face in opposite directions.

(2) Further, the configurations of the first and second lens arrays can be modified as follows.

FIG. 8 shows a modified first lens array 14
It is explanatory drawing which shows the relationship between 0'and the 2nd lens array 150 '. First and second lens arrays 140 ', 1
The curved surfaces of the respective small lenses 142 'and 152' of 50 'are arranged so as to face the -x direction. Similar to the embodiment, the first
The positions of the respective small lenses 142 'of the lens array 140' are shifted in the x direction, and accordingly, the respective small lenses 152 'of the second lens array 150' are arranged.
It is arranged in a misaligned manner. Each small lens 142 ', 15
The distances between 2'are set to be equal.

Further, the lenses of the respective small lenses 142 'of the first lens array 140' have their planes on the exit surface side displaced in accordance with the displacements of the curved surfaces so that the lenses have substantially the same thickness, It is formed like a step. The “thickness” of the lens is the incident surface of the lens (the apex of the curved surface of the lens).
Means the maximum distance between and the exit surface (plane).

Here, the first lens array 14 of the modified example
When 0 is replaced with the first lens array 140 in the embodiment, the thickness of each small lens 142 is different. Even with this change in thickness, each small lens 1
Since the magnifying power of the image of 42 changes, in the first lens array 140 ′ of this modification, the small lenses 142 ′ are formed to have substantially the same thickness.

Also in the illumination optical system using the first and second lens arrays 140 'and 150' of this modification, each of the small lenses of the first lens array 140 'is similar to the illumination optical system 100 of the embodiment. Since the size of the irradiation area formed on the illumination area LA (liquid crystal light valve) by the partial light flux emitted from the lens 142 ′ can be made substantially equal, the illumination area can be efficiently illuminated.

When the curved surfaces of the small lenses of the first and second lens arrays are arranged so as to face the exit surface side, the small lenses of the second lens array have substantially the same thickness. As described above, the planes on the incident surface side of the respective small lenses of the second lens array may be formed so as to be displaced according to the displacement of the position of the curved surface.

As described above, at least some of the plurality of first small lenses of the first lens array are decentered lenses and are formed at different positions along the optical axis direction of the illumination optical system. Therefore, the second small lenses of the second lens array may be formed so that the distances between the second small lenses and the corresponding first small lenses are substantially equal to each other.

(3) In the above embodiment, the illumination optical system 100
Includes a superimposing lens 170, but can be omitted if the second lens array 150 has a superimposing function. In this case, the degree of eccentricity of each small lens 152 of the second lens array 150 may be changed.

(4) In the above embodiment, the substantially parallel light flux emitted from the light source device 120 is incident on the first lens array 140, but it is emitted from the light source device 120 and is condensed. The advancing light or the light advancing while spreading may be incident. In general, the first lens array may have a plurality of first small lenses for splitting the light beam emitted from the light source device into a plurality of partial light beams.

(5) In the above embodiment, each small lens of the first lens array 140 has a substantially rectangular shape.
Each lenslet may have other shapes. In general,
It is desirable that the illumination optical system 100 has a similar shape to a predetermined illumination area illuminated.

(6) In the above embodiment, the case where the positions of the three first small lenses arranged from the central side to the outer peripheral side along the y direction of the first lens array are sequentially changed has been described. The positions of two adjacent first lenslets among the three first lenslets may be the same.

Generally, among the plurality of first small lenses,
It suffices that the positions of the first small lenses arranged in the predetermined direction monotonously change from the center side of the first lens array toward the outer peripheral side.

(7) In the above embodiment, as described in FIG. 5, since the decentering lens is used as each small lens of the first lens array 140, the position of each small lens changes in order. However, the present invention can be applied to a case where a decentering lens is used for at least a part of the plurality of small lenses. Generally, at least some of the plurality of first small lenses are decentered lenses and are formed at different positions along the optical axis direction of the illumination optical system, and the plurality of second small lenses are The optical path lengths between the corresponding first small lenses may be substantially equal to each other.

(8) In the above embodiment, a transmissive liquid crystal panel is used as the electro-optical device, but a reflective liquid crystal panel may be used. Also in this case, the same action and effect as in the case of using the transmissive liquid crystal panel can be obtained.

(9) In the above embodiment, the projector 10
Although 00 has a liquid crystal panel as an electro-optical device, a micro-mirror type light modulation device may be provided instead. As the micromirror type optical modulator, for example, DMD (digital micromirror device) (trademark of TI Co.) can be used. Generally, the electro-optical device may be any device that modulates incident light in accordance with image information.

(10) In the above embodiment, the projector 1000 that displays a color image has been described as an example, but the same applies to a projector that displays a monochrome image.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a projector to which the present invention is applied.

2 is an explanatory diagram showing an enlarged illumination optical system 100 of FIG. 1. FIG.

3 is an explanatory diagram showing an enlarged view of a first polarization generating element array 160A of FIG. 2. FIG.

4 is an explanatory diagram showing a first lens array 140 of FIG. 2 in an enlarged manner. FIG.

FIG. 5 is an explanatory view showing a schematic cross section of various lens arrays in which the respective small lenses are arranged similarly to FIG.

FIG. 6 is an explanatory diagram showing a relationship between a first lens array 140 and a second lens array.

FIG. 7 is an explanatory diagram showing an enlargement magnification of an image of a small lens 142 of the first lens array 140.

FIG. 8 is an explanatory diagram showing a relationship between a first lens array 140 ′ and a second lens array 150 ′ according to a modified example.

[Explanation of symbols]

1000 ... Projector 100ax ... System optical axis 100 ... Illumination optical system 200 ... Color light separation optical system 220 ... Relay optical system 300R, 300G, 300B ... Liquid crystal light valve 320 ... Cross dichroic prism 340 ... Projection optical system 120 ... Light source device 122 ... Lamp 124 ... Reflector 125 ... UV removal filter 126 ... Parallelizing lens 140 ... First lens array 142 ... first small lens 142a, 142b, 142c ... First small lens 140A, 140B, 140C ... First lens array 142A, 142B, 142C ... First small lens 150 ... Second lens array 152 ... second small lens 152a, 152b, 152c ... Second small lens 150A ... second lens array 152A ... second small lens 152Aa, 152Ab, 152Ac ... Second small lens 160 ... Polarization generation optical system 160A, 160B ... Polarization generator array 162 ... Shading plate 162a ... Opening surface 162b ... Shading surface 164 ... Polarizing beam splitter array 164a ... Polarization separation film 164b ... Reflective film 164c ... Glass material 166 ... λ / 2 retardation plate 170 ... Superimposing lens LA ... illuminated area S1, S2 ... Distance SC ... Screen f1 ... focal length f2 ... focal length β: magnification

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13357 H04N 5/74 A H04N 5/74 G02B 27/00 V F term (reference) 2H052 BA02 BA03 BA09 BA14 2H088 EA14 EA15 HA18 HA24 HA25 HA28 MA04 2H091 FA29Z FA41Z FD07 FD12 LA03 5C058 AB03 BA05 EA12 EA51

Claims (8)

[Claims] 1. An illumination optical system for illuminating a predetermined illumination area, comprising: a light source device; and a plurality of first light fluxes for splitting a light flux emitted from the light source device into a plurality of partial light fluxes. A first lens array having small lenses, and a plurality of first lens arrays arranged in the vicinity of positions where a plurality of partial ray bundles emitted from the first lens array are condensed and corresponding to the first small lenses. A second lens array having two small lenses, wherein at least some of the plurality of first small lenses are provided so that positions along the optical axis direction of the illumination optical system are different. The illumination optical system is characterized in that the plurality of second small lenses are provided so that the distances to the corresponding first small lenses are substantially equal to each other. 2. The illumination optical system according to claim 1, wherein at least a part of the plurality of first small lenses is a decentering lens, and the plurality of first small lenses are arranged in a predetermined direction. An illumination optical system in which the positions of the arrayed first small lenses are monotonically changed along the optical axis direction from the center side of the first lens array toward the outer peripheral side. 3. The illumination optical system according to claim 2, wherein at the boundary between two adjacent first small lenses arranged in the predetermined direction, the curved surfaces of the two adjacent first small lenses are adjacent to each other. An illumination optical system that is formed so as to be continuous. 4. The illumination optical system according to claim 2, wherein the plurality of first small lenses and the plurality of second small lenses are respectively arranged along the optical axis direction. Curved surfaces are formed in directions opposite to each other, and the thicknesses of the first and second small lenses arranged in the predetermined direction increase from the center side of the first and second lens arrays toward the outer peripheral side. An illumination optical system that changes monotonically. 5. The illumination optical system according to claim 2, wherein each of the plurality of first small lenses and the plurality of second small lenses has a curved entrance surface side and a flat exit surface side. Among the plurality of first small lenses, the position of the plane on the exit surface side of the first small lenses arranged in the predetermined direction is from the center side of the first lens array toward the outer peripheral side. An illumination optical system that monotonously changes along the optical axis direction. 6. The illumination optical system according to claim 2, wherein each of the plurality of first small lenses and each of the plurality of second small lenses has a flat incident surface side and a curved exit surface side. Among the plurality of second small lenses, the position of the plane on the incident surface side of the second small lenses arranged in the predetermined direction is from the center side of the second lens array toward the outer peripheral side. An illumination optical system that monotonously changes along the optical axis direction. 7. The illumination optical system according to claim 1, further comprising: the plurality of partial ray bundles emitted from the second lens array on the predetermined illumination area. An illumination optical system comprising a superimposing lens for superimposing. 8. A projector for projecting and displaying an image, comprising: the illumination optical system according to claim 1; and an electro-optical device that modulates light from the illumination optical system according to image information. A projection optical system for projecting the modulated light obtained by the electro-optical device.