JP2003140261A - Projection type video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the ray convergence angle to a video display element without increasing the size of a video display device and degrading the efficiency of light utilization for the purpose of realizing a small size, high luminance and high contrast. SOLUTION: A reflector has a reflecting surface of a shape to reflect the luminous flux from a light source so a to reflect the same to converge and is so formed as to make respective lens cells forming a first lens array mutually eccentric.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device using an image display element such as a liquid crystal panel, and more particularly to a liquid crystal projector device and a reflection type liquid crystal projector device.

[0002]

2. Description of the Related Art There is known a projection-type image display device such as a liquid crystal projector for illuminating an image display element such as a liquid crystal panel with light from a light source so as to enlarge and project an image on the liquid crystal panel. 2. Description of the Related Art In recent years, transmissive or reflective image display devices have been downsized, and performance such as resolution has been improved. Along with this, projection-type image display devices have been embodied in a wide variety of usage forms such as video image display and computer image display.

Such a projection-type image display device is required to be compact, have high brightness, have uniform screen brightness, and be capable of displaying images with high contrast.

For downsizing, it is effective to downsize the image display element itself. At present, a liquid crystal projector using a liquid crystal panel having a diagonal size of 1 inch or less is also embodied. However, the miniaturization of the image display device has a problem that the utilization efficiency of light is reduced and the increase in brightness is hindered.

As means for increasing the brightness, Japanese Patent Application Laid-Open No. 4-633
A polarization beam splitter as disclosed in Japanese Patent No. 18 is used to generate a random polarization P
There is a method in which polarized light and S polarized light are separated and combined using a prism.

In general, an image display device (eg, a liquid crystal display device) can obtain good contrast characteristics when light rays that are nearly parallel are incident, and the contrast characteristics deteriorate as the incident angle of the light rays increases. Tend to do. On the other hand, as an optical system that realizes high brightness while avoiding an increase in the incident angle, it is disclosed in Japanese Patent Laid-Open No. 6-342158.
There is one using a lens having a conical surface as disclosed in Japanese Patent Publication No.

Further, as means for improving the uniformity of the brightness of the screen, there is, for example, an integrator optical system using two lens arrays as described in Japanese Patent Laid-Open No. 3-111806.

FIG. 6 is a sectional view showing the structure of an illumination optical system including a conventional light source, a reflector, and an optical integrator, and a light beam passing process. For simplification, parts such as mirrors are omitted and the drawing is shown without bending.

In FIG. 6, 1 is a light source, 50 is a reflector that reflects a light beam from the light source, and 60 is a first lens array in which a plurality of rectangular aperture-shaped lens elements (hereinafter referred to as lens cells) are arranged in a matrix. , The incident light beam is divided into a plurality of light beams as many as the lens cells. Reference numeral 70 denotes a second lens array in which a plurality of lens cells are arranged similarly to the first lens array 60, and reference numeral 80 denotes a plurality of polarized lights arranged in an array provided so as to face the plurality of lens cells of the second lens array 70. A polarization conversion element having a polarization conversion function for emitting a desired polarized wave by a beam splitter (not shown) and a 1 / 2λ phase difference plate (not shown), 90 is a condenser lens, 1
Reference numeral 0 is a condenser lens. Reference numeral 2 is a video display element, for example, a liquid crystal display element. First lens array 60, second lens array 70, polarization conversion element 80, condenser lens 9
The part formed by 0 is particularly called an optical integrator.

The light emitted from the light source 1 arranged at the position of approximately the focal point of the reflector 50 is reflected by the parabolic reflector 5 and the light beam emitted from the center of the light source 1 is substantially parallel to the optical axis of the illumination optical system. Is emitted. The emitted light enters each lens cell of the first lens array 60 and is divided into a plurality of light beams, and the respective divided emitted lights are guided to the corresponding lens cells of the second lens array 70. . The light emitted from the second lens array 70 passes through the polarization conversion element 80, is aligned into a desired polarized wave (for example, S polarized wave), is condensed by the condenser lens 90, and is superimposed and irradiated on the image display element 2. Achieve uniform illumination. If the distance from the condensing lens 90 to the image display element 2 is constant, the focusing angle 22 of the light beam to the image display element 2 also changes depending on the size of the outer size 21 of the second lens array 70. The condenser lens 10 makes the convergent light flux from the condenser lens 90 substantially parallel to the optical axis,
This is for irradiating the image display element 2 substantially vertically.

On the other hand, in order to improve the contrast of the projected image on the screen (not shown), the focusing angle 2
It is desirable to make 2 small.

Next, FIG. 7 is a sectional view showing the structure of another conventional example in which the focusing angle 22 is made small and the process of passing light rays.
In FIG. 7, reference numeral 23 denotes a conical condenser lens which has a function of narrowing a parallel light flux from the reflector 50 by a conical convex incident surface and returning a light flux that has been stopped from being parallel to a substantially parallel conical concave exit surface. . The same parts as those in FIG.

The conical condenser lens 23 narrows the light beam emitted from the reflector 50 to reduce the focusing angle 22.

[0014]

In order to further increase the brightness, it is conceivable to increase the size of the reflector so that the luminous flux from the light source can be effectively used, but it is clear from FIG. In addition, the incident angle of the light flux on the image display element increases, and the contrast of the projected image decreases. In order to increase the brightness while suppressing the increase of the incident angle to the image display element, there is a method of using the conical condensing lens having the conical surface of FIG. 7 described above.
A lens having a diameter substantially equal to the opening of the reflector and having a large thickness in the optical axis direction is required, which causes a problem of increasing the size of the device.

An object of the present invention is to solve the above problems and to provide a projection type image display apparatus which can reduce the incident angle of a light beam to an image display element without increasing the size of the apparatus while suppressing the reduction of light utilization efficiency. To provide.

[0016]

In order to solve the above problems, in the first invention, a light beam from a light source reflected by a reflector is converted into a plurality of light beams by an optical integrator having a plurality of lens arrays. Is a projection type image display device in which a light beam that has been optically modulated by the image display device is projected onto a screen by a projection optical system, and the reflector is a light beam from the light source. The optical axis of each lens cell that has an ellipsoidal reflecting surface that reflects the light so as to converge, and that constitutes the first lens array closest to the light source in the optical integrator is It is eccentric so as to be substantially converged on the corresponding lens cell of the second lens array arranged in the latter stage, and the light beam from the reflector is demultiplexed by the optical integrator. It is configured so that it is divided into a number of light beams and is irradiated onto the image display element.

In the second invention, the light beam from the light source reflected by the reflector is divided into a plurality of light beams by an optical integrator having a plurality of lens arrays, and the light beams are irradiated onto the image display device, and the image is displayed. A projection type image display device for projecting a light beam light-modulated by a display element onto a screen by a projection optical system, wherein the reflector has a parabolic reflection surface, and the light source is from a focal position of the reflector. Is also disposed on the side of the optical integrator, and the light flux from the light source is reflected by the reflector and enters the optical integrator as a convergent light flux, and is the first light source closest to the light source in the optical integrator. The optical axis of each lens cell that constitutes the lens array is the same as that of the corresponding lens cell of the second lens array that is arranged downstream of the light flux from the reflector. Of which eccentric to converge substantially at the center, the light beam from said reflector, said optical integrators - divided into a plurality of light beams in data, configured to irradiate on the image display element.

In the third aspect of the invention, the light beam from the light source reflected by the reflector is divided into a plurality of light beams by an optical integrator having a plurality of lens arrays, and the light is projected onto the image display element. A projection type image display device for projecting a light beam optically modulated by the image display element to a screen by a projection optical system, wherein the reflector is provided on a first focal point located on the reflector side and on the optical integrator side. The light source has an elliptical reflecting surface having a second focal point located therein, and is located at a position set according to a distance between the first focal point and the second focal point so that the light flux from the reflector converges. , And the optical axis of each lens cell forming the first lens array closest to the light source in the optical integrator has a light beam from the reflector arranged in the rear stage. The lens array is eccentric so as to be substantially converged to each corresponding lens cell, and the light beam from the reflector is divided into a plurality of light beams by the optical integrator and irradiates the image display element. To configure.

Further, the optical axis position of each lens cell forming the first lens array is arranged outside according to the distance from the center of the lens array, or the first lens array is formed. Each lens cell that makes up
The oblique light flux from the reflector is converted into a substantially parallel light flux, and the light is focused on each lens cell forming the second lens array.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

The present invention is characterized by the arrangement of the light source, the shape of the reflector, and the optical integrator.

In the section of the prior art, the prior art in which the conical condenser lens is used in order to reduce the incident angle of the light beam on the image display element has been described. However, in the present invention, the conical condenser lens described above has , The reflector and the first lens array share the two functions of narrowing the light beam and returning it in parallel,
We realized that the converging angle of the light beam to the image display element was made small without using the conical condenser lens. This will be described with reference to FIG.

FIG. 1 is a sectional view showing the structure and optical path of an illumination optical system of a projection type image display apparatus according to an embodiment of the present invention. In FIG. 1, 5 is a reflector having an elliptical shape, and 6 is a polarization beam of a polarization conversion element that constitutes a converged light beam from the reflector 5 and constitutes an optical integrator.
1 is a first lens array for irradiating a light splitter (not shown). Since the convergent light flux enters the first lens array 6, the aperture diameter becomes smaller than that of the conventional one. Reference numeral 7 is a second lens array, 8 is a polarization conversion element, and 9 is a condenser lens. Second
The lens array 7, the polarization conversion element 8, and the condenser lens 9 are the first
The outer size corresponds to the aperture of the lens array. Reference numeral 26 denotes a light beam from the light source 1, which is reflected by the reflector 5 and emitted toward the image display element 2. The same parts as those in FIG.

In FIG. 1, the reflector 5 has an elliptical reflection surface, and the light source 1 is placed at the first focal position of the ellipse shape of the reflector 5. Here, the first focus of the ellipsoidal reflector is one of the two focal points of the ellipsoidal shape of the reflector, which is closer to the reflector reflecting surface. The light beam 26 reflected by the reflector 5 is narrowed down to be a convergent light beam and enters the first lens array 6. Each lens cell of the first lens array 6 collects the incident light flux while returning the light flux to be parallel, and each lens cell of the second lens array 7 and the corresponding polarization conversion element 8 are efficiently passed through each lens cell. The surface shape of the lens cell is determined.

The optical axis of each lens cell of the first lens array 6 will be described below. FIG. 2 is a plan view showing the optical axis position of each lens cell of the first lens array 6 according to the present invention. Optical axis position 2 of each lens cell of the first lens array 6
As shown in FIG. 2, 4 is a position that is shifted outward according to the distance from the center of the lens array.

FIG. 3 illustrates movement of the optical axis position of each lens cell of the first lens array, that is, eccentricity. Figure 3
(A) shows the vicinity of the reflector and the first lens array (one side of the main optical axis of the illumination optical system) of the illumination optical system shown in FIG. As is apparent from FIG. 3A, as the distance between the reflection position of the reflector 5 and the main optical axis 27 of the illumination optical system of the light beam 26 reflected by the reflector 5 increases, the first lens array It can be seen that the angle of incidence on each lens cell of No. 6 is large. Figure 3 (b) shows
One lens cell 6i of the first lens array of FIG. 3 (a)
And a ray diagram near the lens cell 7i of the second lens array corresponding to this lens cell. In this ray diagram, for ease of explanation, the lens action in the lens cell is ignored,
Further, the light flux within this range is assumed to be substantially parallel. First
The lenses of the second lens array 7 corresponding to the convergent light flux that enters the lens cells 6i of the first lens array 6 from the reflector 5 while the pitch between the lens cells adjacent to each other of the first lens array 6 and the second lens array 7 is the same. In order to efficiently pass through the cell 7i, the light flux incident on the lens cell 6i may be passed through substantially the center of the lens cell 7i. At this time, it can be seen that the passing position of the light beam 28 passing through the center of the lens cell 7i at the lens cell 6i is not on the center of the lens cell 6i but on the side opposite to the main optical axis 27 side. Since this deviation obviously depends on the incident angle of the convergent light beam to the first lens array 6, the larger the incident angle is, the larger the deviation is in the peripheral lens cells. By disposing the optical axis 24 of the lens cell 6i at this shifted position, the light beam incident on the lens cell 6i can be efficiently guided to the vicinity of the optical axis position which is the center of the lens cell 7i. Figure 3 (c) shows
The ray diagram when the optical axis 24 of the lens cell 6i is disposed at the above-mentioned shifted position is shown. It is clear that the light flux incident on the lens cell 6i can be condensed near the optical axis position which is the center of the lens cell 7i. The focal length of the lens cell 6i of the first lens array 6 is determined so that the combined focal position considering the converging action of the ellipsoidal reflector 5 is near the lens cell 7i of the second lens array 7. Be present.

Returning to FIG. 1, the convergent light beam that is focused by the reflector 5 and is incident on the first lens array 6 is made into a substantially parallel light beam as described above by the first lens array 6, and the second lens array 7 and the polarized light beam are polarized. The light is guided to the conversion element 8, condensed by the condenser lens 9, the focusing angle 22 is reduced, and the image display element 2 is irradiated with the superimposed light.

The light emitted from the reflector 5 is focused and then enters the first lens array 6, so that the first lens array 6
Can reduce the outer size, and thus the outer size 7 of the second lens array can also be reduced. As a result, the focusing angle 22
Can be reduced, and the contrast of the projected image on the screen 18 can be improved.

Further, in the same configuration as that of FIG. 1, when the reflector has a paraboloidal shape, as shown in FIG. 4A, the light source 1 is arranged on the focus position 25 of the parabolic reflector 50. Then, the light flux reflected by the reflector 50 becomes a parallel light flux and is not focused, but as shown in FIG. 4B, the light source 1 is moved from the focus position 25 of the parabolic reflector 50 to the light flux exit side. By moving the reflector, it is possible to obtain substantially the same effect as when the ellipsoidal shape is used for the reflector.

Further, in the same configuration as that of FIG. 1, the case where the reflector has an ellipsoidal shape having a second focal length longer than that of the ellipsoidal surface of FIG. 1 and the case where the shape of the reflector has a parabolic shape Similarly, the converging action of the reflector is reduced. Therefore, by moving the arrangement of the light source 1 from the first focus position to the light beam emission side, it is possible to obtain substantially the same effect as when the ellipsoidal shape is used for the reflector.

Further, in the same configuration as that of FIG. 1, when the reflector has an elliptical shape having a second focal length shorter than that of the elliptical surface of FIG. 1, and when the reflector has a parabolic shape. On the contrary, even if the arrangement of the light source 1 is moved to the side opposite to the light beam emission side, it is possible to obtain substantially the same effect as when the ellipsoidal shape is used for the reflector.

FIG. 5 shows an embodiment in which the illumination optical system of the present invention is applied to a projection type image display device.

In FIG. 5, 2R, 2G, and 2B are image display elements respectively corresponding to the three primary colors of RGB, 3 is a projection lens, 4 is a mirror, 10R, 10G, and 10B are condenser lenses, 11 is a color synthesizing prism, and 12 , 13 is a dichroic mirror, 14 is a mirror, 15 is a first relay lens, 16 is a second relay lens, 18 is a screen, 1
Reference numerals 9 and 20 denote mirrors. The same parts as those in FIG.

The light beam emitted from the light source 1 is reflected by the reflector 5
Are collected and emitted to the first lens array 6.
The first lens array 6 divides the incident light beam into a plurality of light beams and guides them so as to efficiently pass through the second lens array 7 and the polarization conversion element 8. In the second lens array 7, each of the constituent lens cells corresponds to the corresponding first lens array 6
The shape of the lens cell of the image display device 2R, 2G, 2B
Project to the side. The projection image of each lens cell of the first lens array 6 is formed by a condenser lens 9 and a condenser lens 10.
R, 10G, 10B, the first relay lens 15, and the second relay lens 16 are superimposed on the respective image display elements 2R, 2G, 2B.

In the process, the dichroic mirror 12,
The white light emitted from the light source 1 is separated into three primary colors of red, green, and blue by the light source 13, and the corresponding image display element 2
It is irradiated to R, 2G, and 2B.

Brightly illuminated image display elements 2R, 2
The images on G and 2B are color-synthesized by the color synthesizing prism 11, and further projected by the projection lens 3.
It can be projected upwards to obtain a large screen image.

In the first relay lens 15 and the second relay lens 16, the optical path length from the light source 1 to the image display element surface of the image display element 2B is longer than that of the image display elements 2R and 2G. Is to supplement.

The condenser lenses 10R, 10G,
Reference numeral 10B suppresses the spread of light rays after passing through the image display elements 2R, 2G, 2B, and realizes efficient projection by the projection lens 3.

Although the present embodiment has been described with respect to the case of using the transmissive image display element, it goes without saying that the same effect can be obtained also in the projection type image display device using the reflective image display element. Nor.

Further, in the above description, the image display element is a liquid crystal display element, and the optical integrator combined with the polarization conversion element is used for uniform illumination in order to improve the light utilization rate, but the invention is not limited to this. However, the essence of the present invention is to reduce the convergence angle to the image display element. For example, a DMD (Digi
In the case of using a tal micro mirror device), polarized light is not utilized unlike liquid crystal, so a so-called optical integrator composed of a first lens array and a second lens array is used without combining polarization conversion elements. It will be.

[0041]

As described above, according to the invention,
Provided is a projection type image display device which, unlike a conventional projection type image display device, reduces the angle of incidence of a light beam on an image display element without using a conical condenser lens and realizes small size, high brightness and high contrast. be able to.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration and an optical path of an illumination optical system of a projection type image display device according to an embodiment of the present invention.

FIG. 2 is a plan view showing an optical axis position of each lens cell of the first lens array according to the present invention.

FIG. 3 is a diagram illustrating movement of an optical axis position of each lens cell of the first lens array, that is, eccentricity.

FIG. 4 is a cross-sectional view showing the movement of light rays when the light source position is moved.

FIG. 5 is a block diagram showing an embodiment in which the illumination optical system of the present invention is applied to a projection type image display device.

FIG. 6 is a cross-sectional view showing a configuration of a conventional illumination optical system and an optical path.

FIG. 7 is a cross-sectional view showing the configuration and optical path of another conventional illumination optical system in which the focusing angle 22 is made small.

[Explanation of symbols]

1 ... Light source, 2R, 2G, 2B ... Image display element, 3 ... Projection lens, 4 ... Mirror, 5 ... Reflector, 6 ... First lens array, 7 ... Second lens array, 8 ... Polarization conversion element, 9
... condenser lens, 10R, 10G, 10G ... condenser lens, 11 ... color combining prism, 12, 13 ... dichroic mirror, 14 ... mirror, 15 ... first relay lens,
16 ... Second relay lens, 18 ... Screen, 19, 2
0 ... Mirror, 21 ... Outer size of second lens array, 2
2 ... Focusing angle, 23 ... Conical condensing lens, 24 ... Optical axis of each lens cell, 25 ... Reflector focal position, 26 ... Luminous flux,
27 ... A main optical axis of the illumination optical system, 28 ... A light flux passing through the center of the lens cell of the second lens array.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/74 H04N 5/74 A (72) Inventor Eiji Yamaguchi 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Formula company Hitachi Ltd. Digital Media System Division (72) Inventor Tsutomu Nakajima 292 Yoshida-cho, Totsuka-ku, Yokohama City, Kanagawa Prefecture F-term (Reference) Hitachi Ltd. Digital Media System Division 2H088 EA12 HA13 HA16 HA20 HA21 HA23 HA25 HA28 MA02 MA06 2H091 FA05X FA10X FA11X FA11Z FA14Z FA21X FA29X FA41Z LA11 LA17 LA18 MA07 5C058 BA05 BA06 BA08 BA23 EA01 EA02 EA12 EA13 EA51

Claims (5)

[Claims] 1. A light beam from a light source reflected by a reflector is divided into a plurality of light beams by an optical integrator having a plurality of lens arrays, and the light beams are irradiated onto the image display element. A projection type image display device for projecting a modulated light flux onto a screen by a projection optical system, wherein the reflector has an elliptical reflection surface for reflecting the light flux from the light source so as to converge, The optical axis of each lens cell forming the first lens array closest to the light source in the optical integrator substantially converges the light flux from the reflector to the corresponding lens cell of the second lens array arranged in the subsequent stage. Eccentricity so that the light flux from the reflector is divided into a plurality of light fluxes by the optical integrator, and the light flux is irradiated onto the image display element. Projection display apparatus characterized by a. 2. A light beam from a light source reflected by a reflector is divided into a plurality of light beams by an optical integrator having a plurality of lens arrays, and the light beams are irradiated onto the image display element. A projection-type image display device for projecting a modulated light beam onto a screen by a projection optical system, wherein the reflector has a parabolic reflection surface, and the light source is the optical integrator rather than a focal position of the reflector. Is disposed on the optical-inverter side, the light flux from the light source is reflected by the reflector and enters the optical integrator as a convergent light flux, and forms a first lens array closest to the light source in the optical integrator. The optical axes of the respective lens cells are arranged such that the light flux from the reflector is located substantially at the center of the corresponding lens cells of the second lens array arranged in the subsequent stage. The projection type image is eccentric so as to be bundled, and the light beam from the reflector is divided into a plurality of light beams by the optical integrator, and the light beam is irradiated onto the image display element. Display device. 3. A light beam from a light source reflected by a reflector is divided into a plurality of light beams by an optical integrator having a plurality of lens arrays, and the light beams are irradiated onto the image display element. A projection type image display device for projecting a modulated light beam onto a screen by a projection optical system, wherein the reflector is a first focal point located on the reflector side and a second focal point located on the optical integrator side.
A first ellipsoidal reflecting surface having a focal point, wherein the first light flux from the reflector converges
The optical axis of each lens cell that configures the first lens array closest to the light source in the optical integrator by disposing the light source at a position set according to the distance between the focal point and the second focal point is: The light flux from the reflector is decentered so as to be substantially converged to the corresponding lens cells of the second lens array arranged in the subsequent stage, and the light flux from the reflector is divided into a plurality of rays by the optical integrator. A projection type image display device, characterized in that it is divided into a light beam and is irradiated onto the image display element. 4. The optical axis position of each lens cell forming the first lens array is arranged to be located outside according to the distance from the center of the lens array. The projection-type image display device according to claim 3. 5. Each lens cell forming the first lens array converts an oblique light beam from the reflector into a substantially parallel light beam and irradiates each lens cell forming the second lens array with condensed light. The projection type image display device according to claim 1, wherein the projection type image display device is configured as described above.